Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using...
Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using polychromatic X-ray and digital detector as alternative of gravimetric method. To quantify polychromatic X-ray projection for evaluating air-dry density, Lambert-Beer's law with the integral value of probability function was used. The integral value was used as weighting factor in the law, and it was determined by conducting simple test at various penetration depths and tube voltage. Mass attenuation coefficient (MAC) of wood also calculated by investigating polychromatic X-ray projection according to species, penetration depth and tube voltage. The species had not an effect on change of MAC. Finally, an air-dry density of wood was estimated by applying the integral value, MAC and Lambert-Beer's law to polychromatic X-ray projection. As an example, the relation of the integral value (${\alpha}$) according to penetration depth (t, cm) at tube voltage of 35 kV was ${\alpha}=-0.00091t{\times}0.0184$ while the regression of the MAC (${\mu}$, $cm^2/g$) was ${\mu}=0.5414{\exp}(-0.0734t)$. When calculation of root mean squared error (RMSE) was performed to check the estimation accuracy, RMSE at 35, 45 and 55 kV was 0.010, 0.013 and $0.009g/cm^3$, respectively. However, partial RMSE in relation to air-dry density was varied according to tube voltage. The partial RMSE below air-dry density of $0.41g/cm^3$ was $0.008g/cm^3$ when tube voltage of 35 kV was used. Meanwhile, the partial RMSE above air-dry density of $0.41g/cm^3$ decreased as tube voltage increased. It was conclude that the accuracy of estimation with polychromatic X-ray and digital detector was quite high if the integral value and MAC of wood were determined precisely or a condition of examination was chosen properly. It was seemed that the estimation of air-dry density by using polychromatic X-ray system can supplant the gravimetric method.
Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using polychromatic X-ray and digital detector as alternative of gravimetric method. To quantify polychromatic X-ray projection for evaluating air-dry density, Lambert-Beer's law with the integral value of probability function was used. The integral value was used as weighting factor in the law, and it was determined by conducting simple test at various penetration depths and tube voltage. Mass attenuation coefficient (MAC) of wood also calculated by investigating polychromatic X-ray projection according to species, penetration depth and tube voltage. The species had not an effect on change of MAC. Finally, an air-dry density of wood was estimated by applying the integral value, MAC and Lambert-Beer's law to polychromatic X-ray projection. As an example, the relation of the integral value (${\alpha}$) according to penetration depth (t, cm) at tube voltage of 35 kV was ${\alpha}=-0.00091t{\times}0.0184$ while the regression of the MAC (${\mu}$, $cm^2/g$) was ${\mu}=0.5414{\exp}(-0.0734t)$. When calculation of root mean squared error (RMSE) was performed to check the estimation accuracy, RMSE at 35, 45 and 55 kV was 0.010, 0.013 and $0.009g/cm^3$, respectively. However, partial RMSE in relation to air-dry density was varied according to tube voltage. The partial RMSE below air-dry density of $0.41g/cm^3$ was $0.008g/cm^3$ when tube voltage of 35 kV was used. Meanwhile, the partial RMSE above air-dry density of $0.41g/cm^3$ decreased as tube voltage increased. It was conclude that the accuracy of estimation with polychromatic X-ray and digital detector was quite high if the integral value and MAC of wood were determined precisely or a condition of examination was chosen properly. It was seemed that the estimation of air-dry density by using polychromatic X-ray system can supplant the gravimetric method.
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제안 방법
All results of the penetration depth, air-dry density and ratio of initial to transmitted X-ray intensity were divided into two groups; group A and B. Firstly, group A was used to calculate the integral value of probability function and MAC. The number of results in group A was 5, 15, 15 and 15 at penetration depth of 20, 40, 60 and 80 mm per each species and tube voltage, respectively.
It was shown that the integral value and the MAC of wood were influenced by the penetration depth in wood and tube voltage although species did not affect the variance of the MAC. Based on the results, air-dry density of wood in group B was evaluated by using the relationship of the integral value and MAC according to penetration depths at each tube voltage. Calculation of density of the specimens in group B was conducting by using Eq.
The difference between previous and this study was that we didn’t get the whole function of probability function but calculate only the integral value of probability function according to tube voltages and penetration depths with experimental method.
Air-dry densities of wood blocks were also calculated by using air-dry density of each specimen, of which air-dry density was0 measured by the gravimetric method. Total number of projections in accordance with the depths of 20, 40, 60 and 80 mm was 10, 25, 25 and 25 per each species and tube voltage. These projections were examined to determine the ratio of initial to transmitted X-ray intensities.
이론/모형
Therefore, an operator who is going to manage X-ray radiation system composed of polychromatic X-ray source and digital detector should select proper X-ray intensity according to what he want to exam, especially air-dry density. Based on these results, the estimation of air-dry density by using polychromatic X-ray and digital detector can supplant the gravimetric method. If the integral value and MAC of wood are determined precisely or a condition of examination is chosen properly, the accuracy of estimation is quite high.
Finally, estimation of air-dry density was conducted by using the Lambert-Beer’s law with the integral value and the MAC.
In this study, an equation of Lambert-Beer’s law with probability function of polychromatic X-ray was introduced to calculate MACs of wood.
The measurement of air-dry density was gained by using the gravimetric method, while the estimated value was obtained by conducting analysis of taken X-ray projection.
The probability function was used as weighting factor in the Lambert-Beer’s law.
The wood density easily can be measured by the amount of absorption as described by the Lambert-Beer’s law when monochromatic X-ray used.
성능/효과
The measurement of air-dry density was gained by using the gravimetric method, while the estimated value was obtained by conducting analysis of taken X-ray projection. It was shown that the integral value and the MAC of wood were influenced by the penetration depth in wood and tube voltage although species did not affect the variance of the MAC. Based on the results, air-dry density of wood in group B was evaluated by using the relationship of the integral value and MAC according to penetration depths at each tube voltage.
0006 cm2/g). The statistical results of t-test with 95% confidence interval about Korean pine-red pine, red pine-larch and larch-Korean pine indicated that there is no significant difference between species. The p-values of two-tail of Korean pine-red pine, red pine-larch and larch-Korean pine were 0.
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