• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.1
• /
• pp.10-15
• /
• 1987

The experiment was designed to determine the proper shading rate and shading materials to decrease the excessive dried leaves during cure of burley tobacco. Five shading rates and seaven shading materials were applied on the pipe vinyl house from initial stage or yellow stage of cure. Temperature was lower and weight-loss of leaves delayed with shading from initial stage to browning stage of cure. Excessive dried leave were largely decreased as shading rate was increased to 70%. However, at shading rate more than 70%, its decreasing extent was fewer. Price per kg and physical properties improved considerably at shading rate of 50%. Shading materials alone could not completely prevent excessive dried leaves but it could decrease them. Orange, white and purple color vinyl among shading materials had so effects of shading as the black shading cloth during curing. However, white color vinyl didn't endure more than a few months due to sunshine. A difference of light quality in visible light was no significance on air curing.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.2
• /
• pp.47-56
• /
• 2008

The objective of this research is to evaluate the optimum recycling methods for the sewage sludge cakes at different microwave power-settings and for different periods of time. The dehydrated sewage sludge cakes used in this study was obtained from N wastewater treatment plan in the P City. The beginning drying processes were carried out in a microwave oven with 2,450 MHz frequency and power ranges of 1kW to 4 kW. The continuous conveyer drying system was also operated with 2,450 MHz frequency and power setting, ranging from of 1 kW to 6 kW. Initial moisture content of the sewage cake is 78~80%, and the moisture content decreased rapidly up to 0.2~2(wt%) within short periods due to breaking the cell walls. This study is also conducted to evaluate the characteristics of sewage sludge cakes with respect to important physical parameters effect on the thermal kinetics for evaporation water in the sludge which are operation times, moisture contents, drying rates, input amounts, flow rates and calorific values. It takes 60 minutes and 120 minutes to reach the critical moisture contents with power setting of 4 kW for 3kg/min and 6kg/min of the flow rates respectively. It takes 120 minutes and 110 minutes to reach the critical moisture contents with flow rates of 2.5 cm/min and sludge input of 6kg/min for the power settings of 4 kW and 6 kW respectively. The most effective value of the power for drying the sludge is 4 kW. Operation with 6kg/min and 4kW on 2cm of the sludge thickness can be effectively and inexpensively to reach the critical moisture contents, when you compare 2cm of the sludge thickness with 1cm and 3cm of the sludge thickness.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.6 no.4
• /
• pp.331-335
• /
• 2018

The purpose of this study is to investigate the feasibility of CFBC artificial fine aggregate as a substitute for natural aggregate used in dry mortar. The basic performance of the flow, compressive strength and dry shrinkage of the dry mortar was evaluated. Four types of test dry mortar specimens using natural aggregate without expansion admixture, a specimen with modified CaO expansion admixture and natural aggregate, a specimen with modified CaO expansion admixture and CFBC artificial fine aggregate, and a specimen using CFBC artificial fine aggregate without modified CaO expansion admixture were evaluated respectively. As a result of evaluation of drying shrinkage performance at 20th day of age, the dry shrinkage performance of the specimen using modified CaO expansion admixture was found to be the highest at $250{\times}10^{-6}$. On the other hand, the specimen containing the modified CaO expansion admixture with CFBC artificial aggregate exhibited a shrinkage of $410{\times}10^{-6}$, and the drying shrinkage of specimen using natural fine aggregate without expansion admixture was $450{\times}10^{-6}$. When the modified CaO expansion material was used, and exhibited performance equal to or higher than that of the shrinkage-drying property.

• Journal of Navigation and Port Research
• /
• v.29 no.3 s.99
• /
• pp.263-268
• /
• 2005

Laboratory evaluation of the effect of fines, confine stress and dry density on the permeability characteristics in sand columns is presented. The triaxial permeability tests were conducted on different contents of fines(5, 15, 25, $35{\%}$), confine stress ($\sigma_3^'=0.5,\;1.0,\;2.0,\;3.0{\cal}kg/{\cal}cm^2$), and dry density($\gamma_d=1.50,\;1.55,\;1.60,\;1.65{\cal}g{\cal}cm^3$). The results of triaxial permeability tests showed that as the contents of fines, confine stress and dry density became increase permeability became decrease. For the contents of fines, when the fines that smaller than $0.01{\cal}mm$ increases the permeability decreases significantly. For the confine stress and the dry density, the permeability is decreased significantly at changes of the confine stress($\sigma_3^'=0.5{\~}1.0{\cal}kg/{\cal}cm^2$) and the dry density($\gamma_d=1.50{\~}1.55{\cal}g/{\cal}cm^3$) at lower levels.

• Korean Journal of Food Science and Technology
• /
• v.17 no.1
• /
• pp.25-32
• /
• 1985

Low-temperature in-bin paddy drying has been examined to study the limitations of this drying method under Korean weather conditions, the initial moisture content of the paddy, the bulk depth and the airflow rate. The results are reported and discussed with regard to drying time, energy requirements and costs, uniformity in the moisture content of the dried kernels and, finally, the quality of the paddy. The tests carried out during the paddy-drying period in 1981 and 1982 have shown that under Korean weather conditions paddy can be dried to safe storage conditions by continuous aeration with ambient air. Depending upon the initial moisture content of the kernels(19.2%-25.5% w.b.), the bulk depth(1.1-3.5m) and the airflow $(3.0-6.9m^3\;air/m^3\;paddy/min)$ the paddy could be dried within 5 to 17 days. The energy requirements and energy costs are shown to be considerably lower than for conventional high-temperature drying. No significant changes in the quality in terms of milling yield, cracking ratio, acid value and germination were observed.

• Journal of Conservation Science
• /
• v.36 no.2
• /
• pp.103-111
• /
• 2020

To compare the cleaning effect of solvents such as water and ethanol used to clean lacquer relics, the components extracted with various solvents were analyzed. A freshly dried lacquer sample and a lacquer sample exposed to ultraviolet radiation for 24 days were treated with water, ethanol, acetone, and hexane, and the dissolved material was detected by pyrolysis-gas chromatography-mass spectrometry. The amount extracted was significantly higher in acetone and ethanol than in hexane, a nonpolar solvent. Water, a highly polar solvent, was relatively efficient for extracting low-molecular-weight materials. After experiencing 24 days of ultraviolet radiation, the lacquer exhibited a significant increase of extracted materials compared with the nonexposed one. This may be due to the degradation of the urushiol chain in the form of polymers, resulting in the formation of low-molecular-weight polar substances, including dicarboxylic acids. In addition to the deterioration status of lacquer relics, such solvent extraction properties will be a crucial consideration in selecting the appropriate cleaning solvent.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.3
• /
• pp.71-76
• /
• 2012

Since sediment in a stable state is disturbed during the process from sediment in a natural state to dredged soil, the turbidity of water is not good. When the dredged soil settles again, the volume change in the sediment occurs. Coagulant and flocculant are added for turbidity mitigation of the water and faster settling process of suspended solid, and the amount of the substances affects the characteristics of the dredged soil. This study is to investigate the characteristics of the dredged soil depending on the amount of three chemical products added to the wet dredged soil and the dry dredged soil through measuring the suspended solids (SS), volume change and sedimentation velocity. The experimental measurements show that the SS decreased, the volume change rate increased, and the sedimentation velocity increased, as the chemical amount increased. In addition, it was found that the dry dredged soil reacted even with little quantity of the chemicals because derelict and microorganism are removed due to the drying process at $100{\pm}5^{\circ}C$.

• The Korean Journal of Food And Nutrition
• /
• v.24 no.4
• /
• pp.649-656
• /
• 2011

In this study, we made Sulgidduk with commercialized dried nonglutinous rice flour and different levels of soybean curd. For physical properties of the bean curd-Sulgidduk, its water content was increased significantly with a growing addition of soybean curd. In chromaticity, its L value(brightness) and a value(redness) were decreased significantly with more bean curd while b value(yellowness) went up in Sulgidduk with a large amount of rice flour but went down significantly in the Sulgidduk with a small amount of it. Its hardness of texture was found to be the highest in the Sulgidduk with the most dried nonglutinous rice flour and it tended to be higher with more rice flour and less soybean curd. For cohesiveness, it was recorded to be the highest in the Sulgidduk without soybean curd and showed a tendency of decreasing by adding the bean curd but increased later significantly. In addition, its springiness and brittleness became larger with addition of more dried nonglutinous rice flour. From these results, the best ratio of the bean curd-Sulgidduk to increase nutrition and absorption and to satisfy physical and sensory properties, was 420 g to 500 g of soybean curd to dried nonglutinous rice flour. Moreover, it was considered to decline the calorie of Sulgidduk by adding soybean curd as a material and to contribute to its commercialization by extending storage and preservation time of soybean curd with a short expiration date.

• Journal of Food Hygiene and Safety
• /
• v.22 no.4
• /
• pp.300-305
• /
• 2007

The purpose of this study is to examine changes in the residues of procymidone and diazinon in Chwinamul, pepper leaves, and young radish according to drying method. When the three vegetables were dried at room with air stream, the residues of procymidone and diazinon increased, but after being adjusted to reflect the decrease in water content of the vegetables, the residues declined by 10 to 83 percent. When they were dried in a oven, the residues of the pesticides in the vegetables also increased, but after being adjusted to reflect the drop in the water content, the residues decreased by 44 to 71 percent. According to the results, the residues of the pesticides mostly decreased after being adjusted to reflect the drop in the water content of the dried vegetables. Therefore, when judging dried agricultural products not only the decreased water content of dried vegetables but also other factors that affect pesticide residues during the drying process should be considered. This raises the need for additional research on such factors.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.7
• /
• pp.37-46
• /
• 2013

Various sizes of gravels are included in the most field soils that are utilized for civil constructions. Especially, the small amounts of gravel are often included in selected soils for backfill materials, earth dams, and subbase ground. In such cases, the small amounts of mixed gravel and its shape may influence the determination of dry density of soils, which results in an inaccurate degree of compaction for soils in the field. In this study, a dry density of sand with various gravel contents (0, 10, 17, 23, 29 and 33%) and three different sizes (2.0-2.36, 3.35-4.75, 5.6-10.0 mm) was experimentally investigated for compacted or loosely packed conditions. The loosely packed sand with gravels was simulated by pouring sand into compaction mould and its density was determined. When a 33% of gravel content was mixed with sand, its dry density increased up to 15-20% for compacted specimen and 20-23% for loosely packed specimen. When a gravel content and size were the same, a dry density of compacted specimen was $0.1-0.16g/cm^3$ higher than that of loosely packed specimen. Even though the same gravel content was used, a dry density of sand with big gravels was $0.04-0.08g/cm^3$ higher than that of sand with small gravels for compacted specimen and $0.03-0.05g/cm^3$ for loosely packed specimen.