KR20200143893A - System for managing goods information in refrigerator using RFID - Google Patents

Abstract

The present invention relates to a system for managing information on goods in a refrigerator using an RFID. According to the present invention, the system for managing information on goods in a refrigerator using an RFID comprises: an RFID reader recognizing carriage of goods in and from the refrigerator through RFID tags mounted on the goods, and providing recognition information; a payment device installed outside the refrigerator, unlocking the refrigerator when user authentication is performed, and outputting list information and price information of the goods carried-out up to now so as to support goods purchase and payment when a refrigerator door is closed; and a management server managing goods storage and release status of the refrigerator and purchase history of each user by performing communications with the RFID reader and the payment device, and selecting a purchase recommendation list among goods stored in the refrigerator by considering the purchase specification of the user corresponding to the user information received at the user authentication so as to give a feedback. The payment device outputs the purchase recommendation list fed back from the management server through a display after the user authentication. The present invention can provide a customized fresh food recommendation service based on individual consumption data by selecting, outputting and providing the purchase recommendation list suitable for the user among the goods stored in the refrigerator based on the purchase history of the user.

Description

Refrigerator product information management system using RFID {System for managing goods information in refrigerator using RFID}

The present invention relates to a refrigerator article information management system using RFID, and more particularly, to a refrigerator article information management system using RFID that supports ordering and payment of products in a refrigerator based on RFID recognition.

With the recent development of the Internet of Things (IoT), interest in smart home appliances is also increasing. Among them, the smart refrigerator contributes to improving the quality of life in that it provides the functions of food management, recipes, and online shopping based on the information of food ingredients inside the refrigerator.

Smart refrigerators, which are currently in use, add IoT and entertainment elements to the functions of general refrigerators to order ingredients, manage food expiration dates, and search for dishes.

However, since smart refrigerators are more expensive than regular refrigerators, they cannot be easily purchased and convenience has not increased significantly. For example, when putting food materials in a smart refrigerator, the user of the refrigerator directly inputs information on the food materials and has to delete them when taking out items.

Recently, RFID (radio frequency identification)-based refrigerator vending machines that can be installed and operated in companies, buildings, and outdoors are attracting attention. The refrigerator vending machine not only manages the receipt and delivery of products in the refrigerator using the RFID sensor module, but also immediately recognizes the exported product through RFID recognition and supports payment for the product when the user who has completed personal authentication takes out the product in the refrigerator. .

As such, the RFID refrigerator vending machine can be easily accessed by anyone and has the advantage of supporting self-payment of products. However, as interest in health and well-being is more concentrated in recent years, it is not limited to product ordering and payment services, but can provide better quality services and related information feedback to users based on their individual consumption history. A new system is required.

The technology behind the present invention is disclosed in Korean Patent Publication No. 2019-0001866 (published on Jan. 7, 2019).

An object of the present invention is to provide a refrigerator article information management system using RFID capable of providing recommendations to a user by selecting a purchase recommendation list from among products held in a refrigerator based on a user's purchase history.

The present invention provides an RFID reader that recognizes the carry-in/out of a product in a refrigerator and provides identification information through a FRID tag mounted on the product, and is installed outside the refrigerator. When user authentication is performed, the refrigerator is unlocked and the refrigerator door is closed. A payment device that supports product purchase and payment by outputting a list and price information of products that have been carried out so far, and the RFID reader and the payment device communicate with the product in/out status of the refrigerator and the purchase history for each user, and the And a management server for selecting and feeding back a purchase recommendation list from among products held in the refrigerator in consideration of the purchase history of the user corresponding to the user information received at the time of user authentication, and the payment device comprises: A refrigerator product information management system using RFID that outputs the purchase recommendation list fed back from a management server through a display is provided.

In addition, when the user authentication is performed, the management server may select the purchase recommendation list based on at least one of a type, calorie, and nutrient of a product purchased by the user within a set time.

In addition, when the user authentication is performed, the payment device may output a message inquiring about the type of product consumed by the user within a set time to the display, receive a response corresponding to the query, and transmit it to the management server. have.

In addition, when the user authentication is performed, the payment device outputs a message to the display for querying whether allergies to a predetermined food ingredient and food ingredient information, and transmits the allergy-causing food ingredient information input in response to the query to the management server. And, the management server may select the purchase recommendation list by reflecting the allergen-causing food ingredient information.

In addition, the management server, when the user authentication is performed again from a user who has a purchase history within a predetermined time, the products held in the refrigerator based on at least one of nutrients and calories for the previously purchased product within the corresponding time. Among them, the purchase recommendation list may be selected.

In addition, the management server, if at least one of the nutrients and calories of the previously purchased product is less than the reference range, among the possessed products, a list of recommendations for purchasing a high nutrient or high calorie product of a condition exceeding the upper limit of the reference range And, if at least one of the nutrients and calories of the previously purchased product is greater than or equal to the reference range, a low-nutrient or low-calorie product with a condition that is less than the lower limit of the reference range among the possessed products is selected as a purchase recommendation list. I can.

In addition, the refrigerator item information management system further includes a sensing device that measures and provides an internal temperature and air pollution level of the refrigerator, and communicates with the management server, wherein the management server comprises: the internal temperature of the refrigerator, air pollution Using the numerical value, the remaining shelf life of the product, and the average distribution temperature observed during the distribution process of the product, prices for the products held in the refrigerator may be discounted and adjusted and the adjusted price may be transmitted to the payment device.

In addition, the average distribution temperature of the product may be a value obtained by an average of all distribution temperatures measured at a predetermined period in at least one transportation vehicle used during the process of distributing the product to the refrigerator.

In addition, the management server may determine the adjusted price P2 of the product using the following equation.

Here, P1 is the standard price of the product, ΔT ₁ is the deviation between the internal temperature of the refrigerator and the normal temperature, ΔN is the deviation between the air pollution level and the normal value of the refrigerator, R is the remaining shelf life of the product, and ΔT ₂ is the average distribution of the product. The deviations between temperature and normal distribution temperature, a, b, c, and d represent weights determined between 0 and 1.

According to the present invention, a customized fresh food recommendation service based on individual consumption data can be provided by selecting and providing a purchase recommendation list suitable for the user from among products held in a refrigerator based on the user's purchase history.

In addition, in the case of the present invention, the price of the product in the refrigerator can be adjusted in consideration of all of the internal temperature of the refrigerator, the air pollution level, the remaining shelf life of the product, and the average distribution temperature of the product, thereby inducing a reasonable purchase by consumers and And inventory management efficiency can be improved.

1 is a diagram showing the configuration of a refrigerator article information management system using RFID according to an embodiment of the present invention.
2 is a diagram showing the configuration of the payment device shown in FIG. 1 in detail.
3 is a diagram showing in detail the management server shown in FIG. 1.
4 is a diagram illustrating a factor used for price adjustment of a product in a refrigerator in an embodiment of the present invention.

Then, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention.

1 is a diagram showing the configuration of a refrigerator article information management system using RFID according to an embodiment of the present invention.

As shown in FIG. 1, a refrigerator article information management system according to an embodiment of the present invention includes an RFID reader 100, a payment device 200, a sensing device 300, and a management server 400.

The RFID reader 100, the payment device 200, and the sensing device 300 are installed for each of the N refrigerators and operated unattended, and support a user's self-purchase/payment for products in the refrigerator.

The RFID reader 100, the payment device 200, and the sensing device 300 are installed for each of the N refrigerators and operated unattended, and are connected to the management server 400 through a network to transmit various data in real time. The RFID reader 100, the payment device 200, and the sensing device 300 support a user's self-purchase/payment for products in the refrigerator.

The management server 400 may be connected to the RFID reader 100, the sensing device 300, and the payment device 200 installed corresponding to each refrigerator through a wired or wireless network to transmit and receive data. Here, in the case of wireless communication, at least one of Wi-Fi, wireless LAN, ZigBee, Bluetooth, RF communication, LoRa, and NB-IoT (NarrowBand-IoT) may be included. .

Each refrigerator holds products (eg, fresh foods, beverages, etc.) to be sold, and may have a transparent door or a transparent window to facilitate the identification of displayed products. Each product received in the refrigerator is equipped with an RFID tag that can recognize and identify the product. In addition, the products received are intended for foods manufactured/processed suitable for refrigerated or frozen storage.

The RFID reader 100 is provided inside the refrigerator, and may recognize the carrying in/out of the product in the refrigerator through the FRID tag mounted on the product and provide the recognition information to at least one of the real-time payment device 200 and the management server 400. .

The payment device 200 is installed outside the refrigerator, and when user authentication is completed, the refrigerator is unlocked, and when the refrigerator door is closed, a list and price information of products carried out so far are output to support product purchase and payment. The payment device 200 may be installed near a door or a handle of a refrigerator to be conveniently operated for user convenience and accessibility.

The order and payment of products in the refrigerator are made as follows. When a user tags or inserts a credit card or smart phone into the payment device 200 installed on the refrigerator door, user authentication is completed and the lock on the refrigerator door is automatically unlocked. Thereafter, when the user pulls out a product desired to be purchased from the refrigerator and closes the door, the RFID reader 100 recognizes the removed product from the refrigerator and transmits the recognition details to the payment device 200.

Then, the payment device 200 may generate order information matched to the user based on the received corresponding details, and output the order details and payment information through the display, and provide a previously authenticated credit card when a purchase confirmation is input. You can automatically pay for the product through

Here, as the payment and authentication means, not only a credit card, but also a postpaid card, a subway bus card, an employee ID, and a user terminal (smart phone) may be used.

The payment device 200 may be implemented in the form of a conventional card terminal and mounted on a refrigerator door. In addition, the payment device 200 may have a touch-type display capable of inputting and outputting information on the front side, and a recognition means (a socket for inserting a card, a recognition surface for wireless recognition of a card or smartphone), etc., may be formed on the front or side. I can.

FIG. 2 is a diagram showing the configuration of the payment device shown in FIG. 1 in detail. As shown in FIG. 2, the payment device 200 includes a communication unit 210, an authentication unit 220, a payment unit 230, and a display unit 240, and is installed near a refrigerator door or handle for user accessibility. Can be.

The communication unit 210 is network-connected to the RFID reader 100 and the management server 400 to communicate and transmit and receive various data.

The authentication unit 220 performs user authentication by directly recognizing authentication means for personal authentication (eg, credit card, transportation card, employee ID) or by tagging or short-range recognition of a smart phone with a payment method. Here, the authentication method is also used as a payment method for the product. In addition, the authentication unit 220 may obtain a purchaser's payment availability and a payment amount limit as recognition information at the time of card reading.

When user authentication is completed, the authentication unit 220 transmits an unlock signal to the refrigerator door opening and closing device (not shown) to unlock the refrigerator door, thereby providing the user with an opportunity to access the products displayed in the refrigerator. Here, the authentication unit 220 may unlock the refrigerator when there is no abnormality after checking whether the purchaser can make payment and the payment amount limit when reading the card.

The payment unit 230 may generate a description of a product taken out by a user, and order and payment information in real time based on information recognized in real time by the RFID reader 100 and provide it to the display unit 240.

The display unit 240 outputs product order details, costs, payment information, and the like, and is implemented in a touch type to receive a purchase confirmation from a user and transmit a payment request to the payment unit 230. Then, the payment unit 230 proceeds with payment through an initially authenticated payment method. Of course, if the user information is the same, it may be possible to change the payment method.

The management server 400 communicates with the RFID reader 100 and the payment device 200 in real time, and manages the status of entering and leaving the refrigerator for each refrigerator and a purchase history for each user.

In addition, the management server 400 inquires the purchase history of the user corresponding to the user information based on the user information transmitted from the payment device 200 at the time of user authentication, and considers the inquired user purchase history. A purchase recommendation list is selected from among the possessed products and feedback is provided back to the payment device 200.

Then, the payment device 200 outputs and provides a corresponding purchase recommendation list fed back from the management server 400 to the corresponding user through the display unit 240 after user authentication. Accordingly, the user may purchase a product in the refrigerator by referring to the purchase recommendation list provided on the display immediately after user authentication to the payment device 200.

For example, when user authentication is performed, the management server 400 inquires the user's past purchase history, and the type of product the user has purchased within a set time (eg, 3 hours, 6 hours, 12 hours, 1 day, etc.) , Calories, nutrients, it is possible to select a purchase recommendation list suitable for the user based on at least one.

For example, if a product purchased by a user within 6 hours was a high-calorie product such as a cake, a recommended list may be selected and provided mainly for low-calorie products among products in the refrigerator.

In addition, based on the purchase history viewed at the same time as the user authentication, if the user purchased the salad for the first time on the day, the second purchase shows a list of foods that can balance nutrition like a protein bar through the display screen. I can recommend it. In this way, the management server 400 may recommend a product through the user's existing purchase history and nutritional analysis of the product.

Of course, in addition to querying the purchase history as described above, information on products consumed by the user may be directly input from the user and a purchase recommendation list may be selected based on this.

To this end, when user authentication is performed through card recognition, the payment device 200 may immediately output a message to the display unit 240 to inquire about the type of product consumed by the user within a set time, and then the corresponding query When a response corresponding to is received from the user, it may be transmitted to the management server 400. Then, the management server 400 may select and provide a purchase recommendation list based on a user's response corresponding to the query.

For example, when user authentication is performed, the payment device 200 may receive a response by outputting a query and selection menu using the display unit 240. For example,'What's your lunch menu today?','Are you a meal replacement?' A response can be received in a manner that induces a user's selection by providing a list of candidate foods or an answer sheet menu for selecting whether to substitute a meal together with a message such as a message. The management server 400 may determine whether there is low/high calorie based on the input food menu (eg, high calorie in case of champon, low calorie in case of salad or sweet potato) or the type of nutrient intake.

As described above, when the user's purchase history does not exist within the set time, the purchase recommendation list may be provided by receiving information on the food menu consumed within the set time directly from the user.

In addition, the present invention may output a message inquiring whether or not the user is allergic to the display unit, receive information on food ingredients causing allergy, and select a purchase recommendation list based on this.

To this end, when user authentication is performed, the payment device 200 may output a message to the display unit 240 to query whether the user is allergic to the user's allergy and allergen-causing food ingredient information, and the allergen-causing food ingredient received in response to the query Information may be delivered to the management server 400.

Then, the management server 400 may select a purchase recommendation list in consideration of information on food ingredients causing allergy to the user. For example, the management server 400 excludes (excludes) products containing allergens among the products held in the refrigerator so that the user can easily avoid allergens when purchasing products in the refrigerator Can be selected.

Of course, the management server 400 may select a purchase recommendation list from among the products currently in the refrigerator based on the user's previous purchase history, excluding a product containing an allergen from among the selected products.

In addition, when the user authentication is performed again from a user who has a purchase history within a predetermined time (eg, 3 hours, 6 hours, etc.), the management server 400 may Based on, a purchase recommendation list may be selected and provided among the products held in the refrigerator.

If, within 3 hours, the user has a history of purchasing an item from the refrigerator, a purchase recommendation list is selected and provided based on the purchase history. Also, among at least one purchase history within 3 hours, a purchase recommendation list may be selected using the most recently purchased product.

Here, the management server 400, when selecting the purchase recommendation list, if at least one of the nutrients and calories of the previously purchased product is less than the reference range, the high nutrient or high nutrient of the condition exceeding the upper limit of the reference range among products held in the refrigerator You can select a calorie product as a purchase recommendation list.

Conversely, if at least one of the nutrients and calories of the previously purchased product is greater than or equal to the reference range, a low-nutrient or low-calorie product with a condition that is less than the lower limit of the reference range among the possessed products may be selected as a purchase recommendation list.

For example, if the calorie reference range was 300 to 500 kcal, and if the calorie of a previously purchased product is less than 300 kcal, a high-calorie product exceeding 500 kcal can be selected from among products in the refrigerator and provided as a recommended list. . Conversely, if the calorie of the previously purchased product is 500 kcal or more, a product with a low calorie less than 300 kcal can be selected from among the products in the refrigerator and provided as a recommended list. The same principle can be applied to the nutrients of a product (eg fat, carbohydrate, sugar).

As such, an embodiment of the present invention can provide a personalized fresh food recommendation service based on individual consumption data of a user. In addition, when a buyer purchases food from the refrigerator more than once on the same day or enters information on a product consumed before purchase, the nutritional balance or calorie balance can be adjusted based on the nutritional or calorie information of the previously purchased or consumed product. You can recommend and provide a list of foods in the refrigerator.

The sensing device 300 measures and provides an internal temperature of the refrigerator and an air pollution level (air pollution degree) in the refrigerator, and communicates with the management server 400. The sensing device 300 may be implemented as a complex sensor including various environmental sensors such as a temperature sensor, an odor sensor, an active oxygen concentration sensor, an air quality sensor, etc., and may be caused by odors, bacteria, and active oxygen as well as the internal temperature of the refrigerator. Each can provide air pollution degree.

In addition, although the sensing device 300 may provide the active oxygen concentration as an air pollution value, various pollution factors, for example, a value calculated by combining the values of odor and active oxygen may be provided as the air pollution value.

Actually, the internal temperature of the refrigerator and the level of air pollution are factors that affect the freshness, deterioration of the product, and taste change of the product stored in the refrigerator. Accordingly, each element sensed by the sensing device 300 is provided to the management server 400 to be compared and monitored in real time with the normal value, and is used as a factor for adjusting the price discount of the corresponding product later. This will be described in more detail later.

In an embodiment of the present invention, the management server 400 may manage product information of each refrigerator based on the carry-in/out information of products in the refrigerator and provide the management information to a manager terminal (not shown). Product information provided here includes personal information of pre-treatment/processing/manufacturer/cooker, product name, manufacturing/processing date, manufacturing/processing place, expiration date, product price, raw material information for each product, nutritional information for each product (sodium, carbohydrate , Cholesterol, fat, protein, etc.), distribution history information, purchase history information, etc. may be included.

3 is a diagram illustrating in detail the management server shown in FIG. 1. As shown in FIG. 3, the management server 400 may include a collection server 410, an analysis server 420, and a corresponding server 430. Each detailed server works in conjunction with its own DB.

The collection server 410 collects cloud operation data of each refrigerator. The collection server 410 collects storage and delivery information of items for each refrigerator, and collects internal temperature and air pollution levels.

The analysis server 420 detects and continuously monitors the analyzed response process in response to the structured and unstructured data and state data of the cloud operation data collected by the collection server 410.

Specifically, the analysis server 420 analyzes the appropriate expiration date for each food by synthesizing the manufacturing/processing date and raw material information of the received food, and synthesizing the nutritional information of each food and the consumption data of the customer to recommend food suitable for the customer. It analyzes, and analyzes state data such as temperature and pollution level in the refrigerator, and transmits the result value to the corresponding server 430 and the web/app. The manager terminal may access the management server 400 through a web/app through a network to check related information.

The response server 430 manages the processing results of the response process analyzed from the analysis server 420, and measures an abnormal signal such as a change in the price of products that are about to expire, temperature and pollution levels exceed the standard values, customer recommendation purchase history, etc. The processing result value of is transmitted to the analysis server 420 and the manager terminal.

4 is a diagram illustrating a factor used for price adjustment of a product in a refrigerator in an embodiment of the present invention.

As shown in FIG. 4, the management server 400 stores the internal temperature (A) of the refrigerator, the air pollution level (B), the remaining shelf life (C) of the product, and the average distribution temperature (D) observed during the distribution process of the product. By using, discount adjustment of the prices of products held in the refrigerator and transmission of the adjusted price to the payment device 200, the discount adjusted price can be immediately reflected at the time of payment of the corresponding product.

Here, the average distribution temperature of the product may represent a value obtained by averaging all distribution temperatures measured at a predetermined period (eg, one hour) in at least one transportation vehicle used during the process of distributing the product to the refrigerator. have.

That is, data on the transportation environment experienced by the product are accumulated for each product, and the averaged value may be reflected in price determination. Distribution temperature measurement can be measured and collected by a temperature sensor installed for each transport vehicle, and data collection can be performed based on the recently spotlighted Block Chain technology.

The management server 400 may determine the adjusted price P2 of the product using Equation 1 below.

Here, P1 is the standard price of the product, ΔT ₁ is the deviation between the refrigerator's internal temperature (A) and the normal temperature, ΔN is the deviation between the air pollution level (B) and the normal value of the refrigerator, and R is the product's remaining shelf life (C ), ΔT ₂ represents the deviation between the average distribution temperature (D) of the product and the normal distribution temperature, and a, b, c, and d represent the weights determined between 0 and 1. In addition, the weights a, b, c, and d may be determined according to the importance of the corresponding factor.

In Equation 1, it can be seen that'+' is assigned only to the term (1+c·R) related to the remaining shelf life, and'-' is assigned to the remaining terms, which means that the longer the remaining shelf life, the better the freshness of the product. The higher the temperature deviation between the temperature inside the refrigerator and the distribution temperature and the air pollution degree deviation inside the refrigerator, the lower the freshness of the product is reflected.

According to the present invention, the price of the product in the refrigerator can be adjusted in consideration of all of the internal temperature of the refrigerator, the air pollution level, the remaining shelf life of the product, and the average distribution temperature of the product, thereby inducing a reasonable purchase by consumers and the consumption rate of the product. And inventory management efficiency can be improved.

In addition, the present invention provides an advantage of providing a personalized fresh food recommendation service based on individual consumption data by selecting and providing a purchase recommendation list suitable for the user from among products held in the refrigerator based on the user's purchase history.

The present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the art will appreciate that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: RFID reader 200: payment device
210: communication unit 220: recognition unit
230: payment unit 240: display unit
300: sensing device 400: management server

Claims (9)

An RFID reader that recognizes the carry-in/out of products in the refrigerator and provides identification information through the FRID tag mounted on the product;
A payment device installed outside the refrigerator and supporting product purchase and payment by unlocking the refrigerator when user authentication is performed, and outputting a list and price information of products carried out so far when the refrigerator door is closed; And
In communication with the RFID reader and the payment device, the product in and out of the refrigerator and the purchase history for each user are managed, and the product held in the refrigerator in consideration of the purchase history of the user corresponding to the user information received at the time of user authentication It includes a management server that selects and feeds back a purchase recommendation list from among them,
The payment device,
A refrigerator article information management system using RFID that outputs the purchase recommendation list fed back from the management server after the user authentication through a display. The method according to claim 1,
The management server,
When the user authentication is performed, a refrigerator article information management system using RFID for selecting the purchase recommendation list based on at least one of a type, calorie, and nutrient of a product purchased by the user within a set time. The method according to claim 2,
The payment device,
When the user authentication is performed, a message inquiring about the type of product consumed by the user within a set time is output to the display, and a response corresponding to the query is input and transmitted to the management server using RFID. system. The method according to claim 1,
The payment device,
When the user authentication is performed, a message inquiring whether or not to be allergic to a predetermined food ingredient and food ingredient information is output to the display, and the allergen-causing food ingredient information input in response to the query is transmitted to the management server,
The management server,
Refrigerator article information management system using RFID for selecting the purchase recommendation list by reflecting the allergen-causing food ingredient information. The method according to claim 1,
The management server,
When the user authentication is performed again from a user who has a purchase history within a predetermined time, the purchase recommendation list is selected from among products held in the refrigerator based on at least one of nutrients and calories for a previously purchased product within the time period. Refrigerator product information management system using RFID. The method of claim 5,
The management server,
If at least one of the nutrients and calories of the previously purchased product is less than the reference range, a high nutrient or high calorie product under conditions exceeding the upper limit of the reference range among the possessed products is selected as a purchase recommendation list,
When at least one of the nutrients and calories of the previously purchased product is greater than or equal to the reference range, a refrigerator using RFID that selects a product of low nutrient or low calorie under a condition that is less than the lower limit of the reference range among the holding products as a purchase recommendation list Goods information management system. The method according to claim 1,
Further comprising a sensing device that measures and provides the internal temperature and air pollution level of the refrigerator and communicates with the management server,
The management server,
Using the internal temperature of the refrigerator, the air pollution level, the remaining shelf life of the product, and the average distribution temperature observed during the distribution process of the product, the price of the products held in the refrigerator is discounted and adjusted, and the adjusted price is transferred to the payment device. Refrigerator item information management system using RFID to be transmitted. The method of claim 7,
The average distribution temperature of the product is,
A refrigerator article information management system using RFID, which is a value obtained by an average of all distribution temperatures measured at a predetermined period in at least one transportation vehicle used during the process of distributing the product to the refrigerator. The method of claim 7,
The management server,
Refrigerator product information management system using RFID that determines the adjusted price (P2) of the product using the following equation:

Here, P1 is the standard price of the product, ΔT ₁ is the deviation between the internal temperature of the refrigerator and the normal temperature, ΔN is the deviation between the air pollution level and the normal value of the refrigerator, R is the remaining shelf life of the product, and ΔT ₂ is the average distribution of the product. The deviations between temperature and normal distribution temperature, a, b, c, and d represent weights determined between 0 and 1.

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