KR101422909B1 - Method of measuring moisture content of wood using near infrared reflectance spectroscopy and method of carbonization control using the near infrared reflectance spectroscopy - Google Patents

Abstract

A method of measuring the surface moisture content of wood using a near-infrared reflectance spectrum and a method of detecting carbonization of wood and preventing fire. A method for measuring water content of wood comprising the steps of providing a specimen, setting a measurement temperature for measuring the water content of the specimen, setting a water content variation at or below a fiber saturation point of the specimen, Measuring a reflectance spectrum of near infrared rays in the specimen, mathematically preprocessing the measured reflectance spectrum, and regression analyzing the mathematically preprocessed data. According to another aspect of the present invention, there is provided a method of controlling the degree of carbonization of wood using near infrared rays, comprising the steps of: providing a specimen; setting a measurement temperature for measuring a moisture content of the specimen; And a step of measuring the reflectance spectrum of the near-infrared ray at the time interval according to the specimen.

Description

TECHNICAL FIELD The present invention relates to a method of measuring moisture content of wood using a near-infrared spectroscopic method and a method of controlling the degree of carbonation of the wood,

The present invention relates to a method for measuring the water content of wood, and a method for measuring the water content of a whole range of woods not only below the fiber saturation point but also above the fiber saturation point without destroying the wood by using the near infrared reflectance spectrum, The present invention relates to a carbonization control method for detecting carbonization and preventing combustion and ignition.

Trees that have been harvested from forests and processed with logwood contain a large amount of moisture. Various physical / chemical / biological properties of wood vary considerably depending on the changes in moisture content and distribution of water. The degree of deformation generation and intensity is determined according to the amount of moisture present in wood and wood products, the growth of microorganisms and the activity of enzymes are determined, the reactivity with various chemical substances is determined, and the calorific value, thermal conductivity and electrical conductivity And the ease of long-term storage, the accurate moisture content measurement in wood is a key issue in determining the criteria for judging the quality of wood products. In addition, since the raw timber causes various defects such as splitting and twisting due to the occurrence of dry stress during the drying process, an optimized drying process is indispensable to use it reasonably. Inadequate management of wood moisture content during storage and transportation often leads to economic loss as well as degradation of wood resources. Measurement and control of water content in various wood processing processes such as painting and adhesion, preservation treatment, biofuel manufacturing pretreatment, and bioraphinery process control can be performed by various physical, chemical and biological properties such as deterioration, deterioration, Lt; RTI ID = 0.0 > and / or < / RTI >

The most common method of determining the water content of wood is pre-drying, which has the disadvantage of breaking the material and taking a long time. Accordingly, various non-destructive or real-time measurement methods such as DC resistance type, capacitance type, microwave, and ultrasonic wave have been devised. Although these measurements are easy to measure the average moisture content, it is difficult to provide information on the surface moisture content that directly affects surface defects. Therefore, it is often necessary to use a real-time, non-contact moisture content measurement technique in a non-equilibrium state in a wood processing process. Also, in the process of heating wood at a high temperature, there is a risk of accidents due to ignition of the material, which may lead to problems such as industrial material loss and machine breakdown. Since wood is an ignitable material, it is necessary to detect the risk of fire in advance and control the process appropriately.

According to embodiments of the present invention, it is intended to provide a method of measuring the surface moisture content of wood in a full moisture content section using near infrared spectroscopy.

It is also intended to provide a method of controlling carbonization that can prevent ignition of wood by using the reflectance spectrum obtained by near infrared spectroscopy.

The method of measuring moisture content of wood according to the above-described embodiments of the present invention includes the steps of providing a specimen, setting a measurement temperature for measuring a moisture content of the specimen, determining a moisture content at a fiber saturation point Measuring the reflectance spectrum of near infrared rays in the specimen, mathematically preprocessing the measured reflectance spectrum, and regression analyzing the mathematically preprocessed data. .

According to one aspect of the present invention, the step of setting the moisture content variation comprises the steps of deriving an equilibrium moisture content in a temperature and humidity chamber to measure a water content below a fiber saturation point, And inducing the equilibrium moisture content after immersing the specimen for a predetermined time. Here, in order to measure the water content of the sample above the fiber saturation point, the specimen includes a step of immersing and humidifying the specimen in the thermo-hygrostat for a certain period of time and forcibly condensing moisture of the specimen inside the thermo-hygrostat. Also, in the step of forcibly condensing the moisture, the humidity-conditioned specimen is subjected to forced condensation of moisture by forming a supersaturated state of the internal air at a temperature of 25 ° C and a relative humidity of 100%.

According to one aspect of the present invention, the mathematical preprocessing step may sequentially perform processing of a 3-point moving average (Smoothing 3 point), a reference value correction (Baseline), and a Norris 2nd gap derivative (gap size = 1).

According to one aspect, the regression analysis step may use PLSR (Partial Least Square Regression).

Meanwhile, the method of controlling carbonization using near-infrared spectroscopy according to another embodiment of the present invention may include providing a specimen, setting a measurement temperature for measuring a moisture content of the specimen, heat treating the specimen Irradiating the specimen with near infrared rays, and measuring the reflectance spectrum of near infrared rays in the specimen at intervals of time.

According to one aspect, the method further comprises measuring the temperature. The step of measuring the temperature may include measuring a surface temperature of the specimen, measuring an internal temperature of the specimen, and measuring a temperature inside the apparatus for heat treatment of the specimen.

According to one aspect, the step of heat-treating the specimen may be performed while the internal pressure of the heat treatment apparatus is maintained at atmospheric pressure and air exchange with the outside of the heat treatment apparatus is performed.

According to one aspect of the present invention, the method may further include correcting reflectance using the optical probe before heat treatment of the specimen.

As described above, according to the embodiments of the present invention, it is possible to quickly measure the surface moisture content of the wood in a non-destructive manner using the near-infrared reflectance spectrum, and to measure the surface moisture content Can be measured. Accordingly, it can be effectively used for quality control by using the measured surface water content to control quality of materials, maintenance of wooden buildings, and introducing them to the top of engineering wood manufacturing companies.

In addition, the high-temperature heating process can be monitored using the reflectance spectrum obtained in the method of measuring the surface moisture content of wood, thereby detecting the degree of carbonization and preventing ignition of the wood.

FIG. 1 is a flowchart illustrating a method of measuring water content of wood and a method of controlling carbonization of wood according to an embodiment of the present invention. Referring to FIG.
2 is a schematic diagram of an apparatus for measuring moisture content of wood according to an embodiment of the present invention.
3 is a graph showing the reflectance spectrum according to the moisture content measured by the measuring apparatus of FIG.
4 is a graph showing a result of mathematical preprocessing performed on the spectrum of FIG.
Fig. 5 is a graph showing the results of the model test of the predicted surface moisture content of the fiber saturated point or less.
FIG. 6 is a graph showing the result of the model test of the predicted surface moisture content of a fiber saturated point or higher.
FIG. 7 is a graph showing the reliability of the surface water content prediction model in the entire water content range by summing the spectra of the sub-fiber saturation point and the anomaly period measured according to the present invention.
8 is a graph showing a regression coefficient of the surface moisture content prediction model of FIG.
FIG. 9 and FIG. 10 are photographs of a heat treatment apparatus for detecting heat and controlling the degree of carbonization of wood according to an embodiment of the present invention.
Fig. 11 is a schematic diagram for explaining the configuration of the heat treatment apparatus of Figs. 9 and 10. Fig.
12 is a graph showing a temperature change in the heat treatment process according to the present embodiment.
13 is a profile graph of measured temperatures measured 32 times with a heat treatment time of 270 minutes.
FIG. 14 is a graph of spectra in the entire heat treatment area of the test piece measured according to an embodiment of the present invention. FIG.
FIG. 15 is a graph showing a spectrum in a range of 0 m (25 ° C.) to 80 m (197 ° C.) in the spectrum of FIG.
FIG. 16 is a graph showing a spectrum of 90 m (200 ° C.) to 270 m (214 ° C.) in the spectrum of FIG. 14.
FIG. 17 is a graph showing absorbance spectrum of a specimen measured according to an embodiment of the present invention, showing a spectrum-concentrated section at 200 ° C / 90m.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to or limited by the embodiments. In describing the present invention, a detailed description of well-known functions or constructions may be omitted for clarity of the present invention.

According to the present invention, the surface moisture content of the wood can be measured using the reflectance spectrum measured by irradiating the wood with near-infrared rays. By monitoring the reflectance spectrum measured as described above, the degree of carbonization of the wood is detected nondestructively in real time Combustion and ignition can be prevented.

First, a method of measuring the moisture content of wood according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 8. FIG. 1 is a flowchart illustrating a method of measuring water content of wood according to an embodiment of the present invention and a method of controlling carbonization for detecting and preventing combustion of wood. Fig. 2 is a schematic diagram of a water content measuring apparatus for wood.

1 and 2, a wooden specimen 1 is manufactured, and near infrared rays are irradiated on the specimen 1 (S1).

The moisture content measuring apparatus 10 comprises an optical probe 11 for irradiating the wood specimen 1 with near infrared rays and obtaining a reflectance spectrum and a light source 12 and a power supply unit 13 for irradiating near- do. And a computer (15) and a spectrometer (14) for acquiring and analyzing the reflectance spectrum in the specimen (1).

The light source 12 uses a tungsten-halogen light source in order to obtain a sufficient amount of light in the near-infrared range and transfers the radiation light to the test piece 1 using the optical probe 11. [

Next, in order to measure the reflectance spectrum from the specimen 1 to the detector 14 (S2), the measured temperature is set (S3) and the water content variation is measured (S4).

For reference, the irradiation of near infrared rays on wood causes the absorption of radiation corresponding to the inherent vibrational energy of the bonds of the molecules constituting the wood to cause the fundamental vibration of the functional groups such as OH, CH, NH, C═O, The reflectance spectrum can be obtained by attenuating the vibration energy corresponding to the first, second, and third overtones (first, second, and third overtone regions) and the combination bands region. In the case of water, the near-infrared region is advantageous for moisture measurement since it has an excitation band in the 1430 and 1920 nm bands.

Here, the measurement temperature is set in consideration of the temperature in a process requiring measurement of water content during processing such as drying, hot pressure, pressurized chemical treatment, adhesion, painting, bio-energy conversion, and biorefinery. The reason why the measurement temperature should be set is to reduce the temperature-dependent error in the water content measurement step using the developed regression equation. Further, the measurement temperature is set to an average temperature when there is a temperature variation. In case of water content below the fiber saturation point, water content variation is set by thermo - hygrostat.

Next, when the equilibrium moisture content of the test piece 1 is induced, the reflectance spectrum of the test piece 1 is measured through the optical probe 11 (S2). The continuous reflectance spectrum obtained by the detector 14 is stored via the computer 15 (S5, S6).

Then, the computer 15 performs mathematical preprocessing (S7) and regression analysis (S8) on the measured reflectance spectrum.

The mathematical preprocessing S7 sequentially performs a 3-point moving average (smoothing (3point)), a reference value correction (baseline), and a Norris 2nd derivative.

Then, a partial least square regression (PLSR) analysis is performed in correspondence with the mathematical preprocessed spectrum and the moisture content (S8). Herein, the PLSR is performed by cross validation and divided into 20 segments. From the final regression equation, we set the final prediction model to a model with low PC and validation R2 of 0.9 or higher.

The moisture content measuring method according to the present invention can measure the surface moisture content of the highly reproducible wood in real time by measuring the water content by performing mathematical preprocessing and regression analysis on the reflectance spectrum obtained in the near infrared rays irradiated on the wood specimen.

Also, at the same time, the reference value of the reflectance spectrum of 900 nm to 1326 nm is obtained from the reflectance spectrum obtained as described above, and the inclination is compared. By monitoring the carbonization degree in real time, it is possible to prevent an accident that may occur in the heating process. Such a method of controlling the degree of carbonization of the wood will be described later with reference to Figs. 9 to 17 (S9).

The moisture content measuring method according to an embodiment of the present invention will be described in detail.

material

The specimen (1) of the wood to be tested according to the present invention was made of pine wood. The specimen (1) was made of sufficient thickness to allow diffuse reflection to occur with sufficient interaction of the specimen (1) with near-infrared rays. For example, in the present embodiment, a disc-shaped specimen 1 having a thickness of 5 mm (fiber direction) and a diameter of 33 mm is used as the minimum thickness of the specimen 1 for sufficient diffuse reflection. Respectively. The reason why the disk-shaped test piece 1 is produced is that in the case of a rectangular test piece, there is a possibility that a concentration gradient of liquid water different from that of a vertex and a corner around the fiber saturation point occurs, (1) was used to minimize the slope of the water content.

How to measure

According to the present embodiment, the moisture content of the test piece 1 was measured by dividing the fiber saturation point to the fiber saturation point or more. The moisture in the wood can be divided into the binding water which is bound to the cell wall cellulose and the free water which combines with the water in the lumen. Generally, at 100% relative humidity, the water content of the wood is known to be around 30%. According to this embodiment, in order to measure the high moisture content section above the fiber saturation point, the wood specimen is immersed in a thermostatic chamber and the internal moisture distribution is made constant, and then the reflectance spectrum is measured.

1. Below fiber saturation point

By varying the temperature and humidity conditions using a temperature and humidity chamber, various equilibrium moisture content (EMC) below the fiber saturation point is induced in the specimen (1).

Here, the thermo-hygrostat is formed so that the reflectance spectrum can be measured inside the thermo-hygrostat. Then, the thermo - hygrostat was set for each condition, and then the reflectance spectrum was measured after humidifying for 24 hours until the equilibrium moisture content was reached. The temperature and humidity conditions and the equilibrium moisture content are shown in Table 1.

Temperature (℃) Relative humidity (%) Target EMC (%) Average water content (%) Standard deviation of water content (%) equipment 25 99 25.62 25.18 1.02 Thermo-hygrostat 95 23.28 18.20 0.39 80 16.40 15.30 0.51 65 11.95 12.90 0.41 50 9.06 9.70 0.30 25 5.47 7.64 0.36

2. Above fiber saturation point

In order to induce the section above the fiber saturation point, it is submerged for a certain period of time inside the thermo-hygrostat. The immersed specimen (1) was taken out of the water bath and allowed to stand in the thermostat for 5 minutes before measuring the reflectance spectrum. The conditions of immersion time and equilibrium moisture content were shown in Table 2.

Temperature (℃) Immersion time (h) Average water content (%) Standard deviation of water content (%) equipment 25 0.5 38.35 2.04 Constant temperature and humidity chamber One 49.40 2.42 3 57.59 2.84 6 68.42 2.26 24 88.45 3.02

In order to obtain a water content distribution between 25% and 36%, the water was forcedly condensed by establishing a supersaturated state of the internal air at a temperature of 25 ° C and a relative humidity of 100%. The water content distribution is shown in Table 3.

Temperature (℃) Relative humidity (%) Time (h) Average water content (%) Standard deviation of water content (%) equipment 25 100 4 28.88 1.02 Constant temperature and humidity chamber 100 10 32.66 0.39

Spectrum processing

A near infrared spectrometer (NIR QUEST 256-2.5, Ocean Optics) was used to measure the reflectance spectrum of wood. In the present embodiment, a near infrared ray (near infrared ray) is used to measure the reflectance by using a tungsten-halogen lamp (20 W) as the light source 12 and using the optical probe 11 as an optical fiber to transmit the reflection spectrum of the surface of the specimen 1 to the detector A spectroscopic analysis system 10 was used. As a standard material, Teflon with a reflectance of 100% was used. The reference value is set by bringing the optical probe 11 into close contact with a standard material, setting the state of the light source to be 100%, and setting the state of the light source to 0%. When the reflectance spectrum is collected, the optical probe 11 is fixed to the probe holder so that the incident light is maintained at 45 DEG to the specimen 1. [ The reflectance data recorded in the computer 15 through the detector is recorded in the 870 nm to 2510 nm band. However, considering the electrical error of the sensor itself, only the band of 1000nm ~ 2400nm was extracted and used for the regression analysis in order to exclude the noise included at both ends.

The mathematical preprocessing sequentially performs the processing of a 3-point moving average (Smoothing 3 point), a reference value correction (Baseline), and a Norris 2nd gap derivative (gap size = 1). And the spectrum that mathematically preprocessed is applied is applied to the PLS 1 model by partial linear regression (PLSR). Here, the spectral preprocessing and regression model was the statistical analysis software The Unscrambler (Ver. 9.7, Camo Inc, Norway).

FIG. 3 is a graph of reflectance spectra according to the water content of the specimen 1 processed as described above, and FIG. 4 is a graph showing the spectra of the final mathematical preprocessing (3-point moving average, reference value correction, Norris 2nd derivative) Respectively.

Referring to FIGS. 3 and 4, it can be seen that the higher the water content, the lower the reflectance as a whole, and the lower the curvature from 1900 nm or more. In the case of the reflectance spectrum, the area where the light absorption occurs has a positive value when the second derivative is passed. 4, it can be seen that the absorption in the region of 1950 nm to 2200 nm is entirely decreased in the region where the water content is higher than the fiber saturation point, and that the absorbance in the region of 1435 nm and 1920 nm It can be confirmed that the region has shifted to the lower wavelength side.

FIG. 5 is a graph showing the results of the model test of the predicted surface moisture content of the section below the fiber saturation point, and FIG. 6 is a graph showing the results of the model test of the surface moisture content prediction model of the section over the fiber saturation point. Here, the fiber saturation point is assumed to be 30% in order to verify the surface water content prediction model. Referring to FIG. 5, it can be seen that R2 is 0.92 and RMSEP is 1.74 for the section below the fiber saturation point, which is a very reliable result. On the other hand, referring to FIG. 6, R2 is 0.90 and RMSEP is 6.15, which is a relatively high RMSEP in the region above the fiber saturation point. The reason why the RMSEP of the section above the fiber saturation point is high is as follows. First, it is assumed that the deviation between the measurement surface and the average water content of the specimen (1) occurs. In the case of the specimen (1) immersed in order to induce the high moisture content section above the fiber saturation point, as mentioned above, since there is a possibility of an error between the surface and the overall average moisture content, an attempt was made to lower the deviation, have. Second, the higher the water content, the more the peak around 1435 nm and the peak near 1920 nm are deflected to the lower wavelength band. Therefore, due to the nature of the regression model using the preprocessed spectral data, It is judged that the coefficient of determination is shown.

The fraction below the fiber saturation point is humidified for 24 hours in a thermostat, so the water content is constant throughout the whole range. On the other hand, in the case of the section above the fiber saturation point, the deviation of the water content of the immersed sample (1) due to uneven distribution of the moisture content, unevenness of the measurement point and the average water content or the liquid water remaining on the surface of the sample (1) Measurement is difficult.

FIG. 7 is a graph showing the reliability of the surface water content prediction model in the entire water content region by combining the measured spectral ranges of the fiber saturation point and the abnormal region, FIG. 8 is a graph showing the regression coefficient (bi) to be. Here, R2 of the model derived from Figs. 7 and 8 is 0.95 and RMSEP is 5.18.

According to the present invention, the near-infrared reflectance spectroscopic analysis can be used to predict the surface moisture content in the near-infrared range of 1,000 nm to 2,400 nm in the 100% water content or less. Using the predictive model, the surface moisture content can be predicted in real time through the non-destructive method, and all the moisture content ranges can be measured. Through this prediction model, it is possible to predict the surface water content during the drying process of the wood to determine an appropriate drying schedule, thereby reducing drying defects. Further, in the predictive model according to the present embodiment, by changing the water content, the carbonization degree of the wood can be controlled through the change of the near-infrared reflection spectrum during the heat treatment process of the wood, and combustion and ignition can be prevented.

In addition, the water content measurement method according to the present invention can be equally applied to woody biomass as well as wood.

The method of controlling the degree of carbonization using near infrared rays according to the present invention is a method of controlling the degree of carbonization of wood by irradiating near infrared rays to wood and detecting the degree of carbonization of the wood using the measured reflectance spectrum, have. In detail, as the carbonization progresses in the heating process, the Cn-H group increases due to decomposition of the main components (cellulose, hemicellulose, lignin), and thus the reflectance in the range of 900 nm to 1326 nm is greatly reduced . By monitoring near infrared rays on the wood and monitoring the vibration interval (900 nm ~ 1326 nm) of the Cn-H functional groups from the obtained reflectance spectrum, it is possible to detect the degree of carbonization due to decomposition of components generated in the high temperature heating process to prevent ignition and combustion of the wood .

Hereinafter, a method of controlling the degree of carbonization of wood will be described in detail with reference to Figs. 1 and 9 to 17. Fig. Since the method of measuring the water content of the above-described wood and the measurement of the spectrum are the same, overlapping explanations are omitted for the same parts and the detection of carbonization is explained in detail.

First, as shown in Figs. 9 to 11, in order to detect the degree of carbonization of the wood, the heat treatment of the wood and the detection of the degree of carbonization are carried out in the heat treatment apparatus 20 of wood.

The wood heat treatment apparatus 20 includes a heat treatment chamber 21 for accommodating a target specimen 2 and providing a space for treating heat and a reflector 22 for irradiating the specimen 2 with near infrared rays, An optical probe 22 for obtaining a spectrum, a temperature sensor 23 for measuring the temperature inside the heat treatment chamber 21, and a pressure adjuster 24 for adjusting the pressure inside the heat treatment chamber 21 .

Before the heat treatment is performed on the specimen 2, reflectance calibration is first performed using a standard material (Teflon) at room temperature in order to increase the accuracy of the measurement. Then, the specimen 2 is inserted and heat- . For example, in the step of correcting the reflectance, the reflectance is corrected by blinking the light source so that the maximum / minimum reflection value is 100%.

Next, data is obtained from the specimen 2 while performing the heat treatment. For example, measurements can be made every 5 minutes at the beginning of heat treatment, and every 10 minutes after 1 hour. Here, the heat treatment is performed by performing a general high-temperature heat treatment in which the pressure inside the heat treatment chamber 21 is maintained at atmospheric pressure and treated while performing air exchange with the outside.

Here, the data to be measured is the reflectance spectrum of the specimen 2, the surface temperature of the specimen 2, the internal temperature of the specimen 2, and the internal air temperature of the heat treatment chamber 21. To this end, the temperature sensor 23 comprises a first sensor 231 adapted to measure the surface temperature of the specimen 2, a second sensor 232 adapted to measure the temperature of the specimen 2, And a third sensor 233 adapted to measure the temperature of the air inside the first sensor 231. The optical probe 22 is provided at a predetermined distance from the specimen 2 so that the surface of the specimen 2 can be irradiated with near infrared rays and the reflectance can be measured.

FIG. 12 is a graph showing a temperature change in the heat treatment process according to the present embodiment, and FIG. 13 is a graph showing a measured surface temperature measured 32 times with a heat treatment time of 270 minutes. 12 and 13, the set temperature is 250 ° C. After 270 minutes, the surface temperature of the test piece 2 is 214 ° C and the internal temperature of the test piece 2 is 214 ° C. The temperature of the air inside the heat treatment chamber 21 is also 214 ° C, which is similar to the surface temperature and the internal temperature of the test piece 2.

14 to 16 are graphs showing the near-infrared reflectance spectrum obtained as described above. 14 is a graph showing a spectrum in a range of 0 m (25 ° C) to 80 m (197 ° C) in the spectrum of FIG. 14, and FIG. 16 is a graph showing a spectrum of 90 m ) To 270 m (214 < 0 > C). And FIG. 17 is a graph of an absorbance spectrum of a specimen obtained according to an embodiment of the present invention.

According to this embodiment, the carbonization degree can be controlled by monitoring the heat treatment of the wood in a non-destructive manner in real time from the reflectance spectrum obtained by irradiating near infrared rays to the wood. In particular, by comparing the slopes of spectra in the vicinity of 900 nm to 1326 nm in the reflectance spectrum, it is possible to detect the degree of carbonization, thereby preventing combustion and ignition, and preventing accidents that may occur in the heating process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The present invention is not limited to the above-described embodiments, and various modifications and changes may be made thereto by those skilled in the art to which the present invention belongs. Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, are included in the scope of the present invention.

1, 2: Psalm
10: Water content meter
11: Optical probe
12: Light source
13: Power supply
14: Detector
15: Computer
20: Heat treatment apparatus
21: heat treatment chamber
22: Optical probe
23, 231, 232, 233: temperature sensor
24: Pressure regulator

Claims (10)

Providing a sample;
Setting a measurement temperature for measuring a moisture content of the specimen;
Setting a water content variation at or below a fiber saturation point of the specimen;
Irradiating the specimen with near infrared rays;
Measuring a reflectance spectrum of near infrared rays in the specimen;
Mathematically preprocessing the measured reflectance spectrum; And
Regression analysis of the mathematically preprocessed data;
Wherein the moisture content of the wood is measured.
The method according to claim 1,
Wherein the setting of the moisture content variation comprises:
Deriving the equilibrium moisture content in a temperature and humidity chamber to measure the water content below the fiber saturation point; And
Inducing an equilibrium moisture content after immersing the specimen for a predetermined time in order to measure a water content higher than a fiber saturation point;
Wherein the moisture content of the wood is measured.
3. The method of claim 2,
In order to measure the water content above the fiber saturation point,
Immersing the inside of the thermo-hygrostat for a certain period of time and humidifying it; And
Compulsorily condensing the moisture of the specimen inside the thermo-hygrostat;
Wherein the moisture content of the wood is measured.
The method of claim 3,
The method of forcibly condensing moisture is a method for measuring the moisture content of wood by compulsorily adjusting the moisture content of the internal air at 25 ° C and a relative humidity of 100% to condense moisture.
The method according to claim 1,
Wherein the mathematical preprocessing step sequentially performs processing of a 3-point moving average (Smoothing 3 point), a reference value correction (Baseline), and a Norris 2nd gap derivative (gap size = 1).
The method according to claim 1,
Wherein the regression analysis step uses PLSR (Partial Least Square Regression).
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