• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.

• Design & Manufacturing
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• v.15 no.4
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• pp.32-36
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• 2021

In this study, the cause of the decrease in transmittance of the outer lens among the causes of the decrease in the amount of light in the automobile headlamp was identified, and the improvement method was selected to determine the effect. The causes of defects that lower the transmittance of the outer lens are divided into a moisture problem and a haze problem. The moisture problem is caused by the temperature difference between the inside and the outside of the head lamp, and the haze problem occurs when the heat inside the head lamp evaporates the haze component contained in the plastic material and attaches it to the outer lens. In order to improve the haze problem that occurs in plastic raw materials, the structures of the bulb light source type headlamp and the LED chip light source type headlamp were analyzed. Among them, the housing material of the LED chip light source type headlamp, which is structurally prone to haze gas, was selected as the test target. In the mass-production injection process of the housing, the drying process was selected as a method to minimize haze gas without adding a separate production process. After extracting a sample every drying time at a constant drying temperature, the sample was put into a haze tester and the residual amount of haze gas was measured. As a result, it was confirmed that the residual amount of Haze gas in the material decreased as the drying time increased.

• Horticultural Science & Technology
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• v.17 no.4
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• pp.467-469
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• 1999

This study was conducted to examine the changes of nutritive substances in the edible potato varieties ('Superior', 'Atlantic', 'Irish Cobbler', 'Dejima') during storage under low temperature condition($4^{\circ}C$, 85-90% RH) from January to May. The items examined in this experiment were moisture, free soluble sugars, starch and vitamin C. The contents of starch and vitamin C decreased with increasing storage period. The rates of decrease in starch and vitamin C contents were high in February and low after that. The contents of moisture and free soluble sugars did not show a constant tendency during storage period. The contents of glucose and fructose were the highest in February and March. Among the four varieties, 'Superior' contained highest vitamin C, free sugar, and moisture, while 'Atlantic' contained the highest starch.

• Journal of Biosystems Engineering
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• v.15 no.3
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• pp.230-243
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• 1990

This study was conducted to investigate the possibility of application of an infrared drying to drying process for red pepper. The performance of seramic heaters and the variation of temperature and moisture content of red pepper were analyzed during an infrared drying of red peppers. Also, the quality of dried red pepper was analyzed. The following results were obtained from this study. 1. The surface temperature of infrared heaters and the rising time required for steady state were mainly affected by electrical power consumed. 2. The heat energy required for heating red pepper was proposed to be calculated by the equation in terms of enthalpy of air and net heat flux by infrared heater in a drying chamber. The statistical model for net heat flux was developed. 3. The performance of the infrared heater used for heating red pepper was much affected by the distance of radiation, and the difference of temperatures appeared between the radiated surface and the inside of red pepper. 4. Electrical capacity of the infrared heater had a significant effect on the heating of red pepper. However, the effect of shape of heater on heating was not significant. 5. The variation of temperature of red pepper largely appeared in the range of 30 to 60% (db) in moisture content. The temperature of red pepper was almost constant at low moisture content. 6. The temperature of red pepper and heating time had significant effects on the quality for radiant heating. 7. When the electrical capacity of infrared heater and the distance of radiation are carefully designed in a dryer with the insulated drying chamber, infrared drying might be very effective in red pepper drying.

• Korean Journal of Food Science and Technology
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• v.28 no.5
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• pp.877-881
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• 1996

The firming rate of cooked rice stored at $4^{\circ},\;20^{\circ}$ and $30^{\circ}C$ were analyzed. The initial and limiting firmness of cooked rice were decreased as the moisture content increased from 57.5 to 69.5%. The firming rate was inversely related to the storage temperature, but was fairly constant at moisture content between $60.5{\sim}65.9%$. The activation energy and $Q_{10}$ value for firming of cooked rice was $-4.07{\times}10^3\;cal/mole$ and 1.26, respectively. No significant difference in firming rate was observed among rice cultivars.

• Journal of the Korean Society of Tobacco Science
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• v.29 no.2
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• pp.98-103
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• 2007

This study compares menthol migration from fillers to filters and mainstream smoke in a type of leaf tobacco and according to the moisture content differences at the range of $11{\sim}15\;%$. The leaf tobacco used in this study consisted of Korea flue cured upper leaves B1O (KFUB1), A40R (KFUA4), lower leaves C1L (KFLC1), CD4L (KFLCD4), burley upper leaves A3T (KBUA3), lower leaves D3W (KBLD3), Orient Basma I/III (OB), Orient Izmir BIG (OI), expanded tobacco (KET), and reconstituted sheet (KRC). Menthol migration to the filter and mainstream was measured under constant conditions for 80 days with intervals of 20 days. In the comparison between flue cured types, there were significant differences in the filter parts, as follows. KFUB1(34.4 %) KFUA4(37.4 %), KFLC1(43 %) and KFLCD4 were 55.7 %. In the comparision between other types of leaf tobaccos, KFUB1 was 34.4 % and KET was 52.6 % at filter parts. In the methol transfer to mainstream smoke was $16.5{\sim}24.2\;%$. The menthol migration to filters was measured based on the moisture content of $11{\sim}15\;%$ for the KFUB1 after storing it for 80 days. The menthol migrations were $36{\sim}40\;%$ at the moisture content of $11{\sim}15\;%$, respectively. The transfers to mainstream smoke were $12.8{\sim}15.8\;%$.

• Korean journal of food and cookery science
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• v.32 no.2
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• pp.168-177
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• 2016

Purpose: The objective of this study was to investigate the quality characteristics of injulmi made with dry glutinous rice flour according to the punching time (1, 4, 7, 10 min) and the frozen storage period (0, 1, 7, 30 days) as compared with the control made by the traditional method. Methods: Moisture content, texture profile, and sensory evaluation were measured in triplicate and color was measured five times. Results: The moisture content was highest in the sample prepared with 7 min of punching time and the control. As the punching time for injulmi increased, moisture content tended to increase. The L-value increased with increased punching time and the L-value was highest in the samples with 5 min and 7 min of punching time whereas the L-value showed no constant trend with frozen storage. The texture profile analysis indicated that adhesiveness, and gumminess decreased significantly with increased punching time, and punching for 7 min resulted in the highest hardness. The results of an acceptance test, showed that the injulmi prepared with dry glutinous rice flour had higher scores for color, flavor, and taste, texture than the control made with the traditional method. The whiteness of injulmi prepared with dry glutinous rice flour increased with longer punching times and, the sample with 10 min punching time and 7 days of frozen storage had the highest score in the acceptance test. Conclusion: These results can be used as primary data for research on the texture of injulmi made with dry glutinous rice flour.

• Korean Journal of Food Science and Technology
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• v.19 no.1
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• pp.1-4
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• 1987

A seasonal variations of chemical components and gel forming ability in wild common carp (Cyprinus car-pio) and conger eel (Astroconger myriaster) caught around Pusan, Korea monthly for one year (from May,1984 to April, 1985) were investigated. During a year variation range in the moisture and crude lipid contents were found in conger eel meat showing 61.0-76.6% and 5.4-20.8%, while crude protein, ash and carbohydrate were no appreciable differences . Ail of the moisture of chemical components were nearly constant in wild common carp for 12 months. The contents of moisture were less, while crude lipid were more in conger eel meat from September to February than those of the other months. Qualities of the fish jelly were the best for that months in conger eel. Fish jellies were good for 12 months in wild common carp. Gel forming ability was related to the content of chemical components and fishing season in conger eel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1183-1189
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• 2014

The accuracy of the resistive-sheet technique in calculating the RCS(Radar Cross Section) of a deciduous leaf is examined in this paper for various thicknesses and dielectric constants, and a range of thicknesses for the resistive sheet technique is proposed. At first, a leaf was assumed to be a lossy dielectric disk, and the dielectric disk was again assumed to be a resistive sheet with an appropriate resistivity for a given thickness, a dielectric constant, and a frequency. Then, the RCS of the leaf was computed using the physical optics(PO) method, and was compared with the calculation results of a numerical analysis: i.e., a commercial tool based on the FEM (Finite Element Method) technique. It was shown that the error increases as the thickness increases. The error was 0.1 dB, for example, when the thickness is 1.2 mm and 3.7 dB when the thickness is 3 mm with a dielectric constant of(21.4, 9.7) at 9.6 GHz. It was also found that the error decreases as the dielectric constant increases. This study will be very useful for calculating the scattering characteristics of numerous leaves in a vegetation canopy for estimating its radar backscatter using scattering model.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.1
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• pp.15-23
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• 2000

RC oscillation method was applied to study the condenser characteristics of two metal sticks insulated by vinyl tube and used in the dielectric constant determinations of most soils. Its capacitance as influenced by the contacted ambient materials was measured as relative capacitance of the sensor sticks compared with the standard one on the RC oscillation circuit. According to the equivalent circuit of the sensor stick set, the measured capacitance was composed of a basic capacitance connected in parallel with sensor stick capacitance, which was composed of lineally connected vinyl tube capacitances and the sensing part capacitance. The dielectric constant (U) of the contacted ambient moist soil located in the sensing part around the sticks interrelated with the other parameters as following equation. $$\frac{1}{C-B}=\frac{k}{U}+Z$$ where C is the output total relative capacitance, B is the hidden and fixed basic relative capacitance, k is a constant related with U, and Z is a constant for the insulating vinyl tube capacitances determined by its thickness and dielectric constant. The constant k is determined by the spacing and length of sensor sticks. The Z value is theoretically an invariable constant, but it may become considerably bigger than the determined in lab if air tube is formed on the surface of sensor sticks by some shocks on them after their installation in soil. Due to the unstability of lab Z value, it may be better to revise it after sensor stick's installation in soil and no shaking shocks should be applied on them.