• 한국가구학회지
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• 제19권1호
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• pp.75-82
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• 2008

A series of the studies on the applied physical properties of main domestic species have been conducted last three years. Equilibrium moisture content(EMC) of Pinus koraiensis, Larix kaemferi, Pinus koraiensis were investigated. The experiments for sorption property were conducted with 20- and 80-mesh wood powder and resulted in their EMC's at various sorption conditions. Amount of moisture sorption and sorption speed of Larix kaemferi were shown the most large values and very fast among three Korean main coniferous wood.

• 한국연초학회지
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• 제18권2호
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• pp.150-159
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• 1996

In this study, to obtain the basic data for the optimum moisture control system, moisture adsorption characteristics, adsorption isotherms models for water and surface physical characteristics of burley and flue-cured tobacco were investigated. By the hypothesis' the phenomenon of moisture adsorption of tobacco is the same as the first order reaction, the wetting constant (k) and equilibrium moisture content were obtained. And activation energy, frequency factors were also calculated by applying its data to Arrhenius equation. The Kamei's empirical formula of moisture adsorption isotherms showed the best agreement with the experimental data and its correlation coefficient (r) was 0.997. It can be seen that specific surface area of burley is 157 m2/g, that of flue-cured is 152 m2/g, -△H1 of adsorbed monolayer is 45,972 J/mol, 45,486 J/mol, respectively, and the condensation heat (40,595 J/mol) being caught in adsorbed multilayer is less than that of monolayer.

• Journal of the Korean Wood Science and Technology
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• 제42권6호
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• pp.653-658
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• 2014

본 연구는 지역 및 계절 변화에 따른 목재의 평형함수율을 조사하기 위해 수행되었다. 국내 73개 장소에서 30년(1981~2010) 동안 축적된 기상자료와 Hailwood-Horrobin 방정식을 이용하여 목재평형함수율을 계산하였으며 계산된 목재평형함수율의 변화 추이를 조사하였다. 평년값(30년 평균값)을 사용하여 계산된 목재평형함수율은 대구가 11.5로 가장 낮았으며 흑산도가 15.8로 가장 높은 것으로 나타났다. 계절별로 살펴보았을 때 여름(6월, 7월, 8월)이 15.3으로 가장 높았으며 가을(9월, 10월, 11월) 13.7, 겨울(12월, 1월, 2월) 12.2, 봄(2월, 3월, 4월) 12.0의 순서로 평형함수율이 낮은 것을 알 수 있었다. 월별 목재평형함수율은 4월이 11.6으로 가장 낮았으며 7월이 16.1로 가장 높은 것으로 나타났다. 지역에 따른 월별 평형함수율의 편차는 제주가 3.0으로 가장 작았으며 흑산도가 8.7로 가장 큰 값을 보여주었다. 목재의 평형함수율은 목재의 수축 및 팽윤과 관련이 있다는 것을 고려할 때 월별 평형함수율의 편차가 큰 지역에서는 평균평형함수율을 고려하여 목재의 건조를 실시해야 할 것으로 보인다.

• 한국식품과학회지
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• 제9권3호
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• pp.199-204
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• 1977

경기도 이천(利川)에서 수확한 고추(새마을 금장고추 2호)를 건조제분하여 평형수분(平衡水分)을 측정하였으며 125, 250, 500, 1,000 krad의 Co-60 감마선을 조사(照射) 후 저장 중 capsaicin, capsanthin 및 미생물 수의 변화를 조사하여 다음과 같은 결과를 얻었다. 1) $25^{\circ}C$에서 고추의 평형수분함량은 상대습도 43.7, 53.3, 64.4, 75.4, 84.3%에서 각각 13, 18, 25, 28, 37%이었다. 2) 제분도(製粉度)가 낮을수록, 즉 고추가루의 입경(粒徑)이 클수록 평형수분함량이 낮아 장기저장에 유리하였다. 3) 고추가루중의 생존(生存)미생물 수는 g당 약 $10^8$개나 되었으며 혼합미생물의 $D_{10}$ 값은 210 krad이었다. 4) 수분, capsanthin은 500, 1,000 krad 조사선량(照射線量)에서 저장중 변화가 거의 없었으나 capsaicin은 방사선조사(照射)에 의하여 부분적으로 파괴되었다.

• 한국식품저장유통학회지
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• 제21권3호
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• pp.334-340
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• 2014

볶음온도에 따른 옥수수 분말의 흡습특성을 구명하기 위하여, 옥수수 낟알을 160, 180, 200, 220, $240^{\circ}C$에서 20분간 볶은 후 분쇄하고, $20^{\circ}C$에서 각 분말의 수분활성도($a_w$) 0.11, 0.33, 0.53, 0.75, 0.90에 따른 평형수분함량(EMC)을 측정하여 등온흡습곡선을 작성하였다. 볶은 옥수수 분말의 등온흡습곡선은 $a_w$ 증가에 따른 EMC 증가가 전형적인 sigmoid 형태를 보였으며, $a_w$ 0.53 이상의 영역에서는 동일 $a_w$에서 볶음온도가 고온일수록 높은 EMC를 나타내었다. 옥수수 분말의 등온흡습곡선은 볶음온도의 뚜렷한 영향이 없이 Oswin, Caurie, Henderson, Halsey 모델로 설명이 가능하였으며, 가장 적합한 모델은 Oswin인 것으로 나타났다. 단분자층 수분함량은 전범위의 $a_w$영역에서 GAB 방정식으로 예측할 수 있었으며, 볶음온도가 높아짐에 따라 증가하는 경향을 보여서 $180^{\circ}C$에서는 0.043 kg $H_2O/kg$ solids, $240^{\circ}C$에서는 0.053 kg $H_2O/kg$ solids을 각각 나타내었다. 이로써 옥수수의 볶음온도가 분말의 $20^{\circ}C$ 흡습특성에 영향을 미치는 것으로 확인되었다.

• Journal of Biosystems Engineering
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• 제36권4호
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• pp.267-272
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• 2011

The latent heat of vaporization in rough rice, brown rice, white rice and rice hull was calculated by Clausius-Clapeyron equation, which does not require complex constraints as in Othmer method. Equilibrium relative humidity and ratio of the latent heat of vaporization with ln$P_{\upsilon}$ and ln$P_S$ were estimated with moisture contents ranging from 10% (d.b.) to 36% (d.b.) with 2% (d.b.) increment and temperatures ranging from $10^{\circ}C$ to $50^{\circ}C$ with $2.5^{\circ}C$ increment. An empirical equation for calculating the latent heat of vaporization in rice was developed as a function of moisture content and temperature. The equation agreed well with the calculated results. The ratio for latent heat of vaporization were the greatest for white rice while they were similar among rough rice, brown rice and rice hull.

• Journal of Biosystems Engineering
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• 제5권1호
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• pp.15-23
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• 1980

Natural-air drying systems have been extensively used for cereal grains, and many researches on the systems have been conducted in foreign countries. However, little research on drying rough rice with natural air has been done. Especially . little research on natural air drying of rough rice based on weather data has been done in Korean. The objective of this study was to present fundamental data for estimating optimum requirements and basic information available for natural air drying of rough rice based on the weather data . The weather data analyzed in this study were the 10-year (1969 to 1978) record of air temperatures, wet-bulb temperatures and relative humidities, which were three-hourly observations in Taegu area. The results of this study are summarized as follows ; 1 From the results of weather data analysis the average air temperature was about $14.8^\circ$and the average relative humidty 67.5% . Average equilibrium moisture content appeared to be 13.8 percent on wet basis, which showed great potential for natural air drying in Taegue area in October. 2. Possible fan operation time based on the equilibrium moisture content of 15% on wet basis was about 14 hours a day during October in Taegu area. Probabilities of possible drying days based on minimum time available for drying in a day were analyzed. 3. Minimum air flow requirements based on the worst year were determined for different fan operation methods and initial moisture contents.

• 동아시아식생활학회지
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• 제14권5호
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• pp.457-462
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• 2004

Physical properties of soybean curd powder prepared with hot air, vacuum and freeze drying methods were investigated. Adsorption characteristics were studied under various water activities (such as 0.11, 0.33, 0.44, 0.55, 0.66, 0.75, 0.85, and 0.93) at 5℃, and prediction models were developed. Equilibrium moisture and monolayer moisture contents were the highest when freeze dried. due to the porous structure. In this result, Oswin model was the best fit for the isotherm of soybean curd. Sorption enthalpy indicated that high moisture content of powder showed lower sorption than that of low moisture content.

• Journal of the Korean Wood Science and Technology
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• 제46권6호
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• pp.637-644
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• 2018

The air permeability of yellow poplar log cross section before and after organosolv pretreatment was investigated, and the moisture absorption of control and organosolv pretreated rectangular parallelepiped specimens was investigated in this study. It was revealed that the diameters of through pores were enlarged and the number of bigger pore was increased by the organosolv pretreatment. The air permeabilities of the cross sections of yellow poplar log were changed from 1.61 darcy to 23.30 darcy, but their weights were reduced by 5 percent. The equilibrium moisture content of control wood specimen at the exposed relative humidity were 5.9 % at 32 %, 9.7 % at 58 %, 14.8 % at 80.5 %, 19.7 % at 90 %, 25.7 % at 95 % and 29.9 % at 100%. The equilibrium moisture content of the specimens pretreated with the parameter of sulfuric acid catalyst of 0.5 % (w/w) were 19.5 % at 32 %, 29.3 % at 58 %, 39.6 % at 80.5 %, 59 % at 90 %, 111.3 % at 95 % and 111.3 % at 100 %, while those pretreated with the parameter of sulfuric acid catalyst of 1.0 % (w/w) were 17.4 % at 32 %, 23.9 % at 58 %, 27.7 % at 80.5 %, 40.6 % at 90 %, 68.8 % at 95 % and 110.0 % at 100 %. The moisture absorption of organosolv pretreated rectangular parallelepiped specimens was higher than that of control specimen.

• Journal of Biosystems Engineering
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• 제11권2호
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• pp.14-22
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• 1986

This study was carried out to find a method which can be used to measure the soil moisture content of the soil bin exactly and quickly. And gypsum block is used as an instrument in measuring soil moisture content in the field of green house farming, etc.. However the characteristics of gypsum block, or the guide line of making gypsum block is not well introduced in Korea. So the information about gypsum block such as the density of gypsum, type of electrode, dimension of electrode, distance between electrodes, density of surrounding soil were included in this study and their effects on the relationship between soil moisture content and electrical resistance were investigated. The results of this study are as follows; 1. The grid type electrode was quicker in accessing the equilibrium condition and showed more sensitive response to the change of soil moisture content than the plate type electrode. 2. The longer the distance between the electrodes, the larger the electrical resistance, and the distance of 3 to 5 mm was recommended. 3. The larger the width of the electrode, the smaller the electrical resistance. However, there was no significance between the levels designed in this study. Considering the size of the gypsum block itself, the adaptible range of width may be 4 to 8 mm. 4. The higher the density of gypsum, the smaller the electrical resistance. And the block of lower density was broken down in the soil of higy moisture content. The optimum ratio of gypsum to water was 7:5. 5. The measuring system used in this study allowed simultaneous, multi-data acquisition. So this system using A/D converter can be applied to the measurement of soil moisture content of soil bin.