KR20220115163A - Air conditioner - Google Patents

Abstract

The present invention relates to an air conditioner and, more specifically, to an electronic device and an evaluation method for evaluating the performance of an air conditioner in a virtual environment. In accordance with one aspect of the present invention, the electronic device includes: a memory storing climate data including temperature and humidity for a predetermined period in a specific area; and a processor. The processor is set to: generate a virtual building located in the specific area and including a predetermined area and a predetermined form; generate a virtual heat source for providing a thermal load to the virtual building; generate a virtual air conditioner including a virtual outdoor unit and a virtual indoor unit; place the virtual air conditioner in the virtual building; calculate a thermal load to be provided to the virtual building based on the climate data; cause the virtual heat source to supply hot or cold air to the virtual building in accordance with the calculated thermal load; communicate a control signal and a control result with the virtual air conditioner such that the virtual air conditioner can be controlled in response to the supplied hot or cold air; calculate air conditioning data including temperature and humidity by sensing the temperature and humidity of the virtual building; and calculate energy consumed for the virtual air conditioner based on the calculated air conditioning data. Therefore, the present invention is capable of minimizing costs and time in regard to the evaluation of the performance of the air conditioner.

Description

air conditioner {Air conditioner}

The present invention relates to an air conditioner, and more particularly, to an electronic device and an evaluation method for evaluating the performance of the air conditioner in a virtual environment.

In general, an air conditioner consists of a compressor that compresses a refrigerant, a condenser that condenses the compressed refrigerant, an expansion device that expands the condensed refrigerant, and an evaporator that evaporates the expanded refrigerant. A device that regulates temperature and humidity.

The amount of heat required to maintain the indoor space at the desired temperature condition is called the heat load. At this time, the amount of heat that must be supplied to keep the temperature of the indoor space higher than the temperature of the outdoor environment is the heating load, and the amount of heat that must be removed to keep the temperature of the indoor space lower than the temperature of the outdoor environment is the cooling load.

The performance of the air conditioner can be measured by the amount of energy input to the air conditioner according to the heating load or the cooling load.

In the conventional case, in order to measure the performance of the air conditioner, the performance was tested by placing the actual air conditioner in a real chamber in which an indoor space and an outdoor environment were simulated. In this case, there was a problem in that the actual chamber was manufactured, the actual air conditioner was installed, and the actual air conditioner was tested while actually operating, so cost and time were excessively required.

In order to solve the above problem, the real chamber is replaced with a virtual building presented in a virtual environment, and the real air conditioner is placed in a virtual building by separating only the outdoor unit controller and the indoor unit controller including the embedded system. A method for testing the performance may be suggested.

However, even in the above case, the actual outdoor unit controller and indoor unit controller are still required, and as a result, the time required to operate the air conditioner is the same as that of the actual air conditioner, and there is a problem that it still takes a lot of time.

An object of the present invention is to provide an electronic device and an evaluation method capable of evaluating the performance of an air conditioner in a virtual environment.

Another object of the present invention is to provide an electronic device and an evaluation method capable of evaluating the performance of the actual air conditioner or the actual air conditioner without the configuration of the actual air conditioner.

Another object of the present invention is to provide an electronic device and an evaluation method capable of evaluating the performance of an air conditioner in various environments.

Another object of the present invention is to provide an electronic device and an evaluation method that require less cost and time in evaluating the performance of an air conditioner.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, a memory for storing climate data including temperature and humidity for a certain period in a specific area; and a processor, wherein the processor is configured to generate a virtual building located in the specific area and having a predetermined area and a predetermined shape, and generate a virtual heat source for providing a heat load to the virtual building, a virtual outdoor unit and a virtual generating a virtual air conditioner including an indoor unit, disposing the virtual air conditioner in the virtual building, calculating a heat load to be provided to the virtual building based on the climate data, and calculating the virtual heat source according to the calculated heat load To supply hot or cold air to the virtual building, and communicate a control signal and a control result with the virtual air conditioner to control the virtual air conditioner in response to the supplied hot or cold air, and control the temperature and humidity of the virtual building An electronic device configured to calculate air conditioning data including temperature and humidity by sensing and calculate energy consumed in the virtual air conditioner based on the calculated air conditioning data may be provided.

Also, an electronic device may be provided, wherein each of the virtual outdoor unit and the virtual indoor unit of the virtual air conditioner includes a control unit including a control logic and a driving unit including a virtual embedded system that communicates with the processor and drives the control unit. .

The electronic device may further include a display, wherein the processor is set to display the calculated energy consumed in the virtual air conditioner using the display.

In addition, the driving unit may be provided with an electronic device that communicates with the processor in a TCP/IP method.

According to one aspect of the present invention, in a method for an electronic device including a memory and a processor to evaluate the performance of an air conditioner, storing climate data including temperature and humidity for a certain period in a specific area in the memory; step (a); (b) generating, by the processor, a virtual building located in the specific area and including a predetermined area and a predetermined shape; (c) the processor generating a virtual heat source for providing a heat load to the virtual building; (d) generating, by the processor, a virtual air conditioner including a virtual outdoor unit and a virtual indoor unit; (e) the processor disposing the virtual air conditioner in the virtual building; calculating, by the processor, a heat load to be provided to the virtual building based on the climate data (f); (g) setting, by the processor, the virtual heat source to supply hot or cold air to the virtual building according to the calculated heat load; communicating a control signal and a control result with the virtual air conditioner so that the processor controls the virtual air conditioner in response to the supplied hot or cold air (h); (i) calculating, by the processor, air conditioning data including temperature and humidity by sensing the temperature and humidity of the virtual building; and calculating, by the processor, energy consumed in the virtual air conditioner based on the calculated air conditioning data (j).

In addition, each of the virtual outdoor unit and the virtual indoor unit of the virtual air conditioner includes a controller including a control logic and a driver including a virtual embedded system that communicates with the processor and drives the controller, and the virtual outdoor unit and the virtual In each of the indoor units, the step (h) may include: (h-1) receiving, by the driving unit, a control signal from the processor; driving the controller based on the control signal by the driver (h-2); and transmitting, by the driving unit, the control result of the controller to the processor (h-3).

In addition, the electronic device may further include a display, and the air conditioner performance evaluation method may be provided, further comprising the step (k) of displaying the calculated energy consumed in the virtual air conditioner through the display.

In addition, the step (h-1) of the driving unit receiving a control signal from the processor and the step (h-3) of the driving unit transmitting the control result of the control unit to the processor (h-3) are air conditioning made in a TCP/IP method. A performance evaluation method may be provided.

In addition, there may be provided an air conditioner performance evaluation method in which the total time required to evaluate the performance of the air conditioner including the steps (b) to (j) is less than the actual time.

According to the electronic device and evaluation method of the present invention, there are one or more of the following effects.

First, by providing a virtual building, a virtual heat source, and a virtual air conditioner, there is an advantage that the performance of the air conditioner can be evaluated in a virtual environment without the real thing.

Second, there is an advantage of being able to evaluate the performance of the air conditioner in a specific area and at a specific time using climate data.

Third, there is an advantage in that the performance of the air conditioner in various buildings can be evaluated because a virtual building can be created under specific conditions.

Fourth, there is an advantage that the performance of the air conditioner under various heat load conditions can be evaluated by calculating a specific value of the heat load.

Fifth, there is an advantage that cost and time can be minimized in evaluating the performance of the air conditioner by testing in a virtual environment.

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 shows the configuration of a conventional HILS-based air conditioner performance evaluation apparatus.
2 shows the configuration of an electronic device of the present invention.
3 is a diagram illustrating that a virtual air conditioner is disposed in an indoor space of a virtual building and a virtual heat source is disposed outdoors.
4 shows the process of the air conditioner performance evaluation method of the present invention.
5 shows an example of annual climate data.
6 shows the real embedded system of the real indoor/outdoor unit controller compared with the virtual embedded system of the present application.
7 is a graph showing a comparison between the total time and actual time spent in evaluating the performance of the air conditioner in a virtual environment.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification. Further, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may exist between each component. It is to be understood that elements may be “interposed” or that each element may be “connected,” “coupled,” or “connected to,” through another element.

In addition, in implementing the present invention, components may be subdivided for convenience of description, but these components may be implemented in one device or module, or one component may include a plurality of devices or modules. It may be implemented by being divided into .

Hereinafter, an electronic device and an evaluation method for evaluating the performance of the air conditioner according to the present invention will be described with reference to the drawings.

The electronic device of the present invention may evaluate the performance of the air conditioner in a virtual environment. In this case, the virtual environment refers to a simulated environment implemented using virtualization technology, and the virtualization technology refers to a technology that enables efficient use of system resources by logically dividing (or integrating) physical computer resources. Virtualization technology can be classified into HILS (Hardware In the Loop Simulation), which implements a simulated environment including real hardware, and SILS (Software in the Loop Simulation) based on a simulation program. In the electronic device of the present invention, the latter SILS virtualization technology is applied, and the simulation program based thereon is referred to as air conditioning simulation. The air conditioning simulation is a program for implementing and processing a series of processes (including steps (b) to (j)) for evaluating the performance of the virtual air conditioner 300 to be described below.

Hereinafter, an electronic device and an air conditioner performance evaluation method of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 2 , the electronic device of the present invention includes a memory M and a processor P.

The memory M is a device for storing information. The memory M may be provided as a writable non-volatile memory (writable ROM) to store data and reflect changes. The memory M may store climate data including temperature and humidity (FIG. 4 step (a)). The climate data may include temperature and humidity data for a certain period of time in a specific area. The climate data may be data calculated by measuring temperature and humidity for a year in a specific area, and this is referred to as annual climate data. 5 shows an example of climate data, and relates to an annual temperature distribution in Seoul.

The data stored in the memory M is not limited to the climate data, and the memory M may store all kinds of data required to evaluate the performance of the air conditioning simulation and the virtual air conditioner 300 .

In order to test the performance of the air conditioner in a virtual environment, the virtual building 100 , the virtual heat source 200 , and the virtual air conditioner 300 should be generated. 3 illustrates a structure in which a virtual building 100, a virtual heat source 200, and a virtual air conditioner 300 are disposed in a virtual environment.

The processor P may generate the virtual building 100 (step (b) of FIG. 4 ). The processor P may generate the virtual building 100 located in a specific area and including a predetermined area and a predetermined shape based on the climate data stored in the memory M. The virtual building 100 may include a virtual indoor space and a virtual outdoor environment.

The processor P may generate the virtual heat source 200 (FIG. 4 (c)). The virtual heat source 200 is configured to provide a heat load to the virtual building 100 .

The processor P may create a virtual air conditioner 300 (step (d) of FIG. 4 ). Referring to FIG. 2 , the virtual air conditioner 300 may include a virtual outdoor unit 310 and a virtual indoor unit 320 .

Each of the virtual outdoor unit 310 and the virtual indoor unit 320 includes control units 311 and 321 including control logic, and driving units 312 and 322 that communicate with the processor P and drive the control units 311 and 321 , respectively. may include.

Like the actual air conditioner, the virtual outdoor unit 310 may include a virtual compressor, a virtual outdoor heat exchanger, a virtual expansion valve, and the like, and the virtual indoor unit 320 may also include a virtual indoor heat exchanger.

The controllers 311 and 321 may include the same control logic as the control logic of the actual outdoor unit and the actual indoor unit. Accordingly, the virtual compressor, the virtual outdoor heat exchanger, the virtual expansion valve, and the virtual indoor heat exchanger can be controlled in the same way as the actual compressor, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger.

2 and 6 , the driving units 312 and 322 may include a virtual embedded system. The virtual embedded system may be implemented in a virtual environment using an embedded design program or tool. The virtual embedded system may be implemented virtually through a Hardware Abstraction Layer (HAL). The virtual embedded system may include a microcontroller, a communication device, a timer, a switch, a display device, an input/output port, etc., like the real embedded system, and all of these may be implemented in a virtual environment.

The drivers 312 and 322 may include a virtual printed circuit board (PCB). The virtual PCB refers to a PCB implemented in a virtual environment using a PCB design program or tool. A virtual embedded system may be placed on the virtual PCB.

The drivers 312 and 322 may drive the controllers 311 and 321 through the virtual embedded system and the virtual PCB. In addition, the virtual embedded system may include a timer as described above, and the timer may adjust the control period of the controllers 311 and 321 .

As described above, the processor P may perform the following process after creating the virtual building 100 , the virtual heat source 200 , and the virtual air conditioner 300 .

The processor P may arrange the virtual air conditioner 300 in the virtual building 100 (step (e) of FIG. 4 ). In this case, the indoor space of the virtual building 100 may be divided, and the virtual air conditioner 300 may be disposed in a specific indoor space among the divided indoor spaces. (Fig. 3)

The processor P may create an outdoor environment of the virtual building 100 based on the climate data stored in the memory M, and the outdoor environment includes outdoor temperature and humidity. In addition, the target temperature and target humidity of the indoor space of the virtual building 100 in which the virtual air conditioner 300 is disposed may be preset. Referring to FIG. 2 , the electronic device of the present invention may include an input device, through which the target temperature and target humidity of the indoor space of the virtual building 100 in which the virtual air conditioner 300 is disposed are determined. can be entered. The processor P may calculate the heat load of the virtual building 100 in which the outdoor environment is created, and may calculate the cooling load or the heating load based on the target temperature and target humidity set in advance or input through an input device. There is (Fig. 4 step (f)).

The processor P may set the virtual heat source 200 to supply hot or cold air to the virtual building 100 according to the calculated cooling load or heating load (step (g) of FIG. 4 ).

The processor P may transmit a control signal to the virtual air conditioner 300 to control the virtual air conditioner 300 in response to the supplied hot or cold air (step (h-1) of FIG. 4 ). In this case, the processor P may transmit the control signal to the driving units 312 and 322 of the virtual air conditioner 300 . When the control signal is transmitted to the drivers 312 and 322 , the drivers 312 and 322 may drive the controllers 311 and 321 ( FIG. 4 step (h-2)). As the controllers 311 and 321 are driven, the virtual outdoor unit 310 and the virtual indoor unit 320 operate. As a result, the refrigerant temperature of the virtual compressor, the virtual outdoor heat exchanger, the virtual expansion valve, and the virtual indoor heat exchanger. , pressure, flow rate, etc. control results can be derived.

The processor P may receive the control result derived from the controllers 311 and 321 ( FIG. 4 step (h-3)). In this case, the driving units 312 and 322 of the virtual air conditioner 300 may transmit the control result to the processor P. The processor P determines the control state of the virtual air conditioner 300 based on the received control result, and determines changes in control conditions and whether the control is continued. Accordingly, the processor P may again transmit the same or changed control signal to the drivers 312 and 322 and receive a new control result from the drivers 312 and 322 . The above process (steps (h-1) to (h-3) of FIG. 4) may be repeated until the temperature and humidity of the virtual building 100 sensed as follows reach the target temperature and humidity.

The processor P may sense the temperature and humidity of the virtual building 100 . The processor P may calculate air conditioning data based on the sensed temperature and humidity (FIG. 4 step (i)). The air conditioning data may include temperature and humidity of a specific indoor space of the virtual building 100 in which the virtual air conditioner 300 is disposed.

The processor P may calculate the energy consumed in the virtual air conditioner 300 based on the calculated air conditioning data (FIG. 4 step (j)). The consumed energy may be power consumption. When the temperature and humidity of a specific indoor space of the virtual building 100 in which the virtual air conditioner 300 is disposed reach the target temperature and the target humidity, the total energy consumed until reaching the target temperature and humidity may be the consumed energy . Unlike the above, when the temperature and humidity of a specific indoor space of the virtual building 100 in which the virtual air conditioner 300 is disposed do not reach the target temperature and humidity, the initial temperature and humidity reach the current temperature and humidity. Based on one hour and the amount of energy consumed so far, the total energy to be consumed to reach the target temperature and humidity may be estimated and calculated.

The processor P may calculate a performance coefficient of the virtual air conditioner 300 based on the calculated consumed energy. The coefficient of performance of the virtual air conditioner 300 may be calculated by dividing the calculated amount of energy and heat by the amount of heat corresponding to the cooling load or the heating load.

Referring to FIG. 2 , the electronic device of the present invention may include an output device O for outputting various data. The output device O may output the location, size, and shape of the virtual building 100 . The output device O may output the arrangement structure of the virtual heat source 200 and the virtual air conditioner 300 . The output device O may output the target temperature and humidity, the current temperature and humidity, the time taken up to the present, and the like. The output device O may output energy consumed in the virtual air conditioner 300 or a coefficient of performance of the virtual air conditioner 300 calculated based on the energy (step (k) of FIG. 4 ). The output device O may further include a display 400, and in this case, various data may be visually output.

Meanwhile, referring to FIG. 2 , the communication method TCP/IP when the processor P transmits a control signal to the driving units 312 and 322 or the driving unit 312 and 322 transmits a control result to the processor P (Transmission Control Protocol/Internet Protocol). In general, the microcontroller of the real embedded system may include a UART (Universal asynchronous receiver/transmitter), so the communication between the real embedded system and the PC uses the UART method. TCP/IP communication takes less than 10ms. On the other hand, in the case of UART communication, the required time is approximately 700ms. Therefore, the communication speed between the virtual embedded system and the processor P of the present application is formed faster than the communication speed between the real embedded system and the processor, and as a result, the time required for steps (h-1) and (h-3) can reduce

The timers of the drivers 312 and 322 may adjust the control period of the controllers 311 and 321 . Through this, after the driving units 312 and 322 receive the control signal from the processor P, based on this, the driving units 311 and 321 are driven to obtain a control result (step h-2). )) can be adjusted. The timer may set the control period to be short, thereby reducing the time required for step (h-2).

As described above, the time required for step (h) when the timer sets the control cycle short and the communication method between the driving units 312 and 322 and the processor P is applied as TCP/IP is, the real embedded system and the UART It takes much less time than when the communication method is applied. Since the time required for step (h) is reduced, the time taken for steps (b) to (j) is also reduced, and as a result, the total time required for evaluating the performance of the air conditioner is also reduced. .

Referring to FIG. 7 , according to the actual comparison test result, the total time required to evaluate the performance of the air conditioner in the virtual environment according to the electronic device of the present invention was measured to be 15 minutes (a), and under the same condition, the actual embedded When the indoor/outdoor unit controller including the system and the UART communication method are applied, the total time (actual time) required for performance evaluation of the air conditioner was measured to be 60 minutes (b). That is, it can be seen that the total time required to evaluate the performance of the air conditioner in the virtual environment according to the electronic device of the present invention is formed by 1/4 to 1/2 of the actual time, and the evaluation time is reduced by 50% to 75%. can

Even though all the components constituting the embodiment of the present invention are described as being combined or operated as one, the present invention is not necessarily limited to this embodiment, and all components within the scope of the present invention are one or more may be selectively combined to operate. In addition, all of the components may be implemented as one independent hardware, but a part or all of each component is selectively combined to perform some or all of the functions of the combined hardware in one or a plurality of hardware program modules It may be implemented as a computer program having Codes and code segments constituting the computer program can be easily deduced by those skilled in the art of the present invention. Such a computer program is stored in a computer readable storage medium (Computer Readable Media), read and executed by the computer, thereby implementing the embodiment of the present invention. The storage medium of the computer program includes a magnetic recording medium, an optical recording medium, and a storage medium including a semiconductor recording device. In addition, the computer program implementing the embodiment of the present invention includes a program module that is transmitted in real time through an external device.

In the above, preferred embodiments of the present invention have been illustrated and described, but the present invention is not limited to the specific embodiments described above, and in the technical field to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Various modifications may be made by those of ordinary skill in the art, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

100 : virtual building
200: virtual heat source
300: virtual air conditioner
310: virtual outdoor unit
311: outdoor unit control unit
312: outdoor unit driving unit
320: virtual indoor unit
321: indoor unit control unit
322: indoor unit driving unit
400: display
I: input device
M: memory
O: output device
P: processor

Claims (9)

a memory for storing climate data including temperature and humidity for a certain period of time in a specific region; and
including a processor;
The processor is
creating a virtual building located in the specific area and having a predetermined area and a predetermined shape;
generating a virtual heat source for providing a heat load to the virtual building;
Creating a virtual air conditioner including a virtual outdoor unit and a virtual indoor unit,
disposing the virtual air conditioner in the virtual building,
calculating a heat load to be provided to the virtual building based on the climate data;
to supply hot or cold air to the virtual building by the virtual heat source according to the calculated heat load;
communicating a control signal and a control result with the virtual air conditioner to control the virtual air conditioner in response to the supplied hot air or cold air;
Sensing the temperature and humidity of the virtual building to calculate air conditioning data including temperature and humidity,
An electronic device configured to calculate energy consumed in the virtual air conditioner based on the calculated air conditioning data. The method of claim 1,
Each of the virtual outdoor unit and the virtual indoor unit of the virtual air conditioner,
a control unit including control logic; and
and a driving unit that communicates with the processor and includes a virtual embedded system that drives the control unit. The method of claim 1,
further comprising a display,
The processor is
An electronic device configured to display the calculated energy consumed in the virtual air conditioner using the display. 3. The method of claim 2,
The driving unit is an electronic device that communicates with the processor in a TCP/IP manner. A method for evaluating the performance of an air conditioner by an electronic device including a memory and a processor, the method comprising:
Storing climate data including temperature and humidity for a certain period in a specific region in the memory (a);
(b) generating, by the processor, a virtual building located in the specific area and including a predetermined area and a predetermined shape;
(c) the processor generating a virtual heat source for providing a heat load to the virtual building;
(d) generating, by the processor, a virtual air conditioner including a virtual outdoor unit and a virtual indoor unit;
(e) the processor disposing the virtual air conditioner in the virtual building;
calculating, by the processor, a heat load to be provided to the virtual building based on the climate data (f);
(g) setting, by the processor, the virtual heat source to supply hot or cold air to the virtual building according to the calculated heat load;
communicating a control signal and a control result with the virtual air conditioner so that the processor controls the virtual air conditioner in response to the supplied hot or cold air (h);
(i) calculating, by the processor, air conditioning data including temperature and humidity by sensing the temperature and humidity of the virtual building; and
and (j) calculating, by the processor, energy consumed in the virtual air conditioner based on the calculated air conditioning data. 6. The method of claim 5,
Each of the virtual outdoor unit and the virtual indoor unit of the virtual air conditioner includes a control unit including control logic and a driving unit including a virtual embedded system that communicates with the processor and drives the control unit,
In each of the virtual outdoor unit and the virtual indoor unit,
The step (h) may include a step (h-1) of the driver receiving a control signal from the processor; driving the controller based on the control signal by the driver (h-2); and transmitting, by the driving unit, a control result of the controller to the processor (h-3). 6. The method of claim 5,
The electronic device further includes a display,
The air conditioner performance evaluation method further comprising the step (k) of displaying the calculated energy consumed in the virtual air conditioner through the display. 7. The method of claim 6,
Step (h-1) of the driving unit receiving a control signal from the processor; and
Step (h-3) of the driving unit transmitting the control result of the control unit to the processor,
A method for evaluating air conditioner performance by TCP/IP method. 6. The method of claim 5,
The air conditioner performance evaluation method in which the total time required to evaluate the performance of the air conditioner, including the steps (b) to (j), is formed to be less than the actual time.

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