• Journal of the Korea Furniture Society
• /
• v.19 no.1
• /
• pp.75-82
• /
• 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.

• Journal of the Korean Society of Tobacco Science
• /
• v.18 no.2
• /
• pp.150-159
• /
• 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
• /
• v.42 no.6
• /
• pp.653-658
• /
• 2014

This research was carried out to investigate equilibrium moisture content (EMC) of wood in outdoor locations in Korea. EMC was calculated using Hailwood-Horrobin equation for 73 different locations in Korea using the 1981 to 2010 climate normal data obtained from the Korea Meteorological Admnistration (KMA). Daegu showed the lowest values of EMC (11.5), and the highest EMC values (15.8) was found in Heuksando. Considering the season effect, summer (June, July, August) showed the highest values 15.3, followed by autumn (September, October, November) 13.7, winter (December, January, February) 12.2, and spring (February, March, April) 12.0. Monthly EMC showed the lowest values 11.6 in April and July showed the highest EMC values 16.1. The smallest changes in monthly EMC were found in Jeju island and Heuksando showed the largest values 8.7. A proper wood drying based on average EMC is more required in the regions with larger variation in EMC.

• Korean Journal of Food Science and Technology
• /
• v.9 no.3
• /
• pp.199-204
• /
• 1977

To improve the storage stability of Korean red pepper (Capsicum annuum), the equilibrium moisture content of the powder and effects of irradiation on the capsaicin, capsanthin and microorganisms were investigated during its storage. The equilibrium moisture contents of the powder at $25^{\circ}C$ and relative humidities of 43.7, 53.3, 64.4, 75.4 and 84.3% were 13, 18, 25, 28 and 37%, respectively, and the larger the particle size was, the lower the equilibrium moisture content was under the same storage conditions. Cobalt-60 gamma irradiation degraded partly the capsaicin in red pepper or in solution at dose levels above 500 krad, but did not affect the moisture and capsanthin contents during its storage. Total viable cell count of the powder was around $10^8$ per gram and $D_{10}$ value for the mixed organisms was 210 krad.

• Food Science and Preservation
• /
• v.21 no.3
• /
• pp.334-340
• /
• 2014

The moisture sorption isotherms of corn powder prepared from corn kernels roasted for 20 min at 160, 180, 200, 220, and $240^{\circ}C$ were determined at $20^{\circ}C$ using the static gravimetric method over the range of water activities ($a_w$) of 0.11~0.90. The moisture sorption isotherms showed a typical sigmoid shape, and the equilibrium moisture content tended to increase with increasing $a_w$, and increased sharply at above 0.75 $a_w$. At above 0.53 $a_w$, the equilibrium moisture content of the roasted corn powder increased with the increase in the roasting temperature. Six mathematical models (Bradley, Caurie, Halsey, Henderson, Kuhn, and Oswin) were used to fit the experimental data. The Oswin, Caurie, Henderson, and Halsey models were found to have suitability for describing the sorption curves, and the Oswin model was the best fit model for all the roasting temperatures. Concerning the monolayer moisture content, the Guggenheim-Anderson-Boer (GAB) equation showed high significance. The monolayer moisture content increased as the roasting temperature was increased, to 0.043 and 0.053 kg $H_2O/kg$ solids in the corn powder roasted at $180^{\circ}C$ and $240^{\circ}C$, respectively. These results suggest that the roasting temperatures of the corn kernels affected the moisture sorption characteristics ($20^{\circ}C$) of the corn powder.

• Journal of Biosystems Engineering
• /
• v.36 no.4
• /
• pp.267-272
• /
• 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
• /
• v.5 no.1
• /
• pp.15-23
• /
• 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.

• Journal of the East Asian Society of Dietary Life
• /
• v.14 no.5
• /
• pp.457-462
• /
• 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
• /
• v.46 no.6
• /
• pp.637-644
• /
• 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
• /
• v.11 no.2
• /
• pp.14-22
• /
• 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.