• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.8-12
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• 1974

1. If one unity is given to the prongs whose ends touch each other for estimating the internal stresses occuring in it, the internal stresses which are developed in the open prongs can be evaluated by the ratio to the unity. In accordance with the above statement, an equation was derived as follows. For employing this equation, the prongs should be made as shown in Fig. I, and be measured A and B' as indicated in Fig. l. A more precise value will result as the angle (J becomes smaller. $CH=\frac{(A-B') (4W+A) (4W-A)}{2A[(2W+(A-B')][2W-(A-B')]}{\times}100%$ where A is thickness of the prong, B' is the distance between the two prongs shown in Fig. 1 and CH is the value of internal stress expressed by percentage. It precision is not required, the equation can be simplified as follows. $CH=\frac{A-B'}{A}{\times}200%$ 2. Under scheduled drying condition III the kiln, when the weight of a sample board is constant, the moisture content of the shell of a sample board in the case of a normal casehardening is lower than that of the equilibrium moisture content which is indicated by the Forest Products Laboratory, U. S. Department of Agriculture. This result is usually true, especially in a thin sample board. A thick unseasoned or reverse casehardened sample does not follow in the above statement. 3. The results in the comparison of drying rate with five different kinds of wood given in Table 1 show that the these drying rates, i.e., the quantity of water evaporated from the surface area of I centimeter square per hour, are graded by the order of their magnitude as follows. (1) Ginkgo biloba Linne (2) Diospyros Kaki Thumberg. (3) Pinus densiflora Sieb. et Zucc. (4) Larix kaempheri Sargent (5) Castanea crenata Sieb. et Zucc. It is shown, for example, that at the moisture content of 20 percent the highest value revealed by the Ginkgo biloba is in the order of 3.8 times as great as that for Castanea crenata Sieb. & Zucc. which has the lowest value. Especially below the moisture content of 26 percent, the drying rate, i.e., the function of moisture content in percentage, is represented by the linear equation. All of these linear equations are highly significant in testing the confficient of X i. e., moisture content in percentage. In the Table 2, the symbols are expressed as follows; Y is the quantity of water evaporated from the surface area of 1 centimeter square per hour, and X is the moisture content of the percentage. The drying rate is plotted against the moisture content of the percentage as in Fig. 2. 4. One hundred times the ratio(P%) of the number of samples occuring in the CH 4 class (from 76 to 100% of CH ratio) within the total number of saplmes tested to those of the total which underlie the given SR ratio is measured in Table 3. (The 9% indicated above is assumed as the danger probability in percentage). In summarizing above results, the conclusion is in Table 4. NOTE: In Table 4, the column numbers such as 1. 2 and 3 imply as follows, respectively. 1) The minimum SR ratio which does not reveal the CH 4, class is indicated as in the column 1. 2) The extent of SR ratio which is confined in the safety allowance of 30 percent is shown in the column 2. 3) The lowest limitation of SR ratio which gives the most danger probability of 100 percent is shown in column 3. In analyzing above results, it is clear that chestnut and larch easly form internal stress in comparison with persimmon and pine. However, in considering the fact that the revers, casehardening occured in fir and ginkgo, under the same drying condition with the others, it is deduced that fir and ginkgo form normal casehardening with difficulty in comparison with the other species tested. 5. All kinds of drying defects except casehardening are developed when the internal stresses are in excess of the ultimate strength of material in the case of long-lime loading. Under the drying condition at temperature of $170^{\circ}F$ and the lower humidity. the drying defects are not so severe. However, under the same conditions at $200^{\circ}F$, the lower humidity and not end coated, all sample boards develop severe drying defects. Especially the chestnut was very prone to form the drying defects such as casehardening and splitting.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.107-115
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• 2017

In this study, the surface check reduction effect of preservative-treated Korean larch round-wood was investigated by applying three physical treatments, such as incising, kerfing, and kiln-drying. Moreover, the possibility of long-term service life was also checked by comparing the depth of surface check and the penetration depth of preservative. A rapid gradient of wood moisture content between surface and center causes a surface check. Thus, the effect of reducing surface check was carried out at the lowest equilibrium moisture content (EMC) condition, temperature ($2^{\circ}C$), humidity (44.6%), in outdoor locations in Korea until the test specimens reach to the 8.6% EMC. As a result, the preservative-treated specimens without incising, kerfing, kiln-drying (Type C) could not ensure the long-term service life due to a large surface check. Because the surface check depth of all specimens was deeper than the penetration depth of preservative. In case of the incising treated specimens (Type I), 80% of them, the depth of surface check was not deeper than the penetration depth of preservative. However, when a kerfing was additionally treated (Type B), a possibility of happening deeper surface check than penetration depth of preservative was increased rather than Type I.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.118-128
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• 1983

Simulation model of natural air grain drying was discussed and modified to predict the changes of grain moisture content and dry matter loss of rough rice drying. The modified simulation model was then validated using actual test data. A series of simulated drying tests using official weather data for 15 years from Beaumont, Texas, was taken to make minimum airflow rate and maximum bed depth of rough rice drying by natural air, under different conditions of initial moisture content of rough rice, airflow rate and harvest date.

• Journal of the Korean Wood Science and Technology
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• v.47 no.6
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• pp.721-731
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• 2019

Air drying depends on species, density, dimension of wood, the geographical location of the air drying yard, and the meteorological factors of air drying site. If there are four seasons with large difference in temperature and humidity like in Korea, the research of the meteorological factors is required in air drying site. In this study, effective air drying days (EADD) of 24 regions in Korea were calculated by using the average monthly temperature, relative humidity, and wind speed. The EADD in 24 regions in Korea was ranged from 239 days to 291 days, with an average 265 days. This result is 5 days increased compared to the average of EADD calculated using the meteorological factors from 1955 to 1984. The results of multiple regression analysis on the EADD and meteorological factors showed that EADD affected in the order of temperature, relative humidity, and wind speed. As a result of dividing Korea into 4 zones of EADD, the zones of EADD were moved northward compared to previous study due to global warming. As basic data for predicting the moisture content (MC) distribution of Korean red pine logs during air drying conducted in Seoul, the average monthly temperature, relative humidity and wind speed for three years from 2016 to 2018 were presented, and the corresponding changes of the equilibrium MC were analyzed.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.186-190
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• 1992

Composite seasoning was stored at the temperature of $40^{\circ}C$ and $50^{\circ}C$, the relative humidity of 11, 32, 57, 65, 75 and 95% without any packaging. The moisture content reached to equilibrium state within short period below 57% RH, but it increased rapidly above 65% RH. The hygroscopic characteristics of compoposite seasoning was similar to each temperature and the amount of absorbed water was decreased at the higher temperature. The optical density due to browning development was increased above 57% RH during storage. L and b value of composite seasoning was decreased according to the increase of temperature and relative humidity. Palatibility of color, taste and flavor, and caking of composite seasoning was sharply decreased above 57% RH during storage.

• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.351-357
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• 2009

This study was conducted to verify the simulation model through the drying test, and investigate effect of factors, such as temperature of drying air, airflow rate, and velocity of the airflow, on the drying. The low temperature drying simulation model was developed based on the circulation dry simulation model presented by Keum et al. (1987), and by modifying low temperature thin layer drying model, equilibrium moisture content model, latent heat of vaporization model, and crack ratio prediction model. The heat pump and experimental dryer with a capacity of 150kg were used for the test. The RMSE between the predicted and measured value was 0.27% (drying temperature), 0.15% (crack ratio), and 2.08% (relative humidity), so the relevance of the model was verified. In addition, the effect of drying temperature, airflow rate, and velocity of the airflow on the drying was examined. The experimental results showed that the crack ratio at drying temperature of $25{\sim}40^{\circ}C$ was allowable. Moreover, at below $30^{\circ}C$, variation of the crack ratio was slight, but drying time was delayed. Given these results, the drying temperature of over $30^{\circ}C$ was effective. As the airflow rate increased, required energy dramatically increased. Whereas drying rate slowly increased, so loss of drying efficiency was caused. Considering these results, the dryer needed to be designed and adjusted to lower than $30\;m^3/min{\cdot}ton$. As velocity of the airflow increased, required drying energy increased when the velocity of the airflow was over $5\;m^3$/hr, while crack ratio and drying rate showed little variation.

• Korean Journal of Food Science and Technology
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• v.18 no.2
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• pp.77-81
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• 1986

The water sorption isotherms of individual insoluble components of corn starch, isolated soybean protein (ISP) and casein and their binary mixtures of corn starch-lSP and corn starch-casein were measured and analyzed. BET monolayer values and Smith plot parameters from the results of sorption isotherms were calculated by mass balance concept . The comparisons between experimental and predicted values resulted in an error of 2.29% for equilibrium moisture content and an error of 2.95% in monolayer value for the mixture 50% corn starch-50% ISP. On the other hand , for the mixture 50% corn starch-50% casein the errors were 2.66% and-5.34%, respectively.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.527-540
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• 2018

In this study, the characteristics of the white charcoal from charcoal kilns made for both charcoal production and thermotherapy and from the traditional charcoal kiln were compared and examined. A charcoal kiln for thermotherapy as a secondary purpose was made to minimize environmental problems such as fine dust and harmful gas generated from sealed charcoal kiln in consideration of comfort and safety. White Charcoal produced from the charcoal kiln for both charcoal production and thermotherapy had higher ash and volatile matter and lower fixed carbon than that from the traditional charcoal kiln. The density of the white charcoal produced from the charcoal kiln for both charcoal production and thermotherapy was slightly higher than that of the traditional one, but the equilibrium moisture content and pH were not significantly different. The calorific value, refinement degree, hardness and anatomical structure were not different between the two. It was concluded that the white charcoal produced from the advanced charcoal kiln for thermotherapy as a secondary purpose meets the quality certification standards of Korea Forest Research Institute.

• Korean Journal of Food Science and Technology
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• v.19 no.6
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• pp.480-485
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• 1987

Quick cooking rice was produced by cooking raw, white long grain rice with three different methods which were atmospheric cooking in electric cooker, autoclaving and precooking followed by autoclaving. The drying rate curve showed that cooking methods affected little the drying pattern of the cooked rice except that precooking treatment before autoclaving retarded dehydration. The quick cooking rice prepared by precooking and autoclaving method among three cooking methods showed the fastest rehydration rate and took 7.5 minutes in reaching equilibrium moisture content by soaking in boiling water. And it had less hard and more cohesive texture than the milled rice cooked by conventional method and the quick cooking rice prepared by electric cooking when reconstituted. The microstructure of quick cooking rice was investigated among cooking methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1137.1-1141
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• 2001

Kochujang-gulbi, a traditional food in Chonnam province of Korea, was prepared with kochujang and dried gulbi slices. The crude lipid contents of kochujang and gulbi in the product were 3.08% and 15.6% at 0 day, respectively. After 7 days, the lipid contents were changed to 8.15% and 9.72%. The moisture content and VBN of kochujang and gulbi in the product were reached to the equilibrium after 7 days. In the kochujang-gulbi product, the TBARS value in gulbi was reduced because the lipid from gulbi permeated into kochujang, while the value in kochujang was increased. To prevent the growth of microorganisms and lipid oxidation from the kochujang-gulbi, 0.5% (w/v) garlic extract, citron essential oil, or ethanol was added to the product. The garlic extract and ethanol were very effective to inhibit the growth of mold and yeast at 2$0^{\circ}C$. The products treated with the garlic extract and citron oil were shown significantly lower microbial number than control for 30 days storage. The addition of citron oil to kochujang-gulbi showed lower TBARS value than other treatment.