• Journal of the Korean Geographical Society
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• v.46 no.1
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• pp.1-19
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• 2011

The physical and chemical characteristics of loess-paleosol sequence in Jeongjang-ri, Geochang basin are examined using the magnetic susceptibility measurement, grain size analysis, OSL age dating, major, rare earth and trace elements analysis. The grain size characteristics of the loess-palesol sequence are obviously different from those of river sediment forming river terrace deposits and the Chinese Loess Plateau. The loess-paleosol sequence consisting of L1, L1LL1, L1S1, L1L2, S1 and L2 from top to bottom is estimated to MIS 2~MIS 6 and the river terrace to MIS 7. The compositions of major, rare earth and trace elements indicate that the sequence show more weathered characteristics than the Chinese Loess Plateau and originated from the Chinese Loess Plateau. These features are in harmony with the previous studies in Korea.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1105-1113
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• 2013

This paper attempted to estimate the emissions of HFC-134a from scrap truck as a result of measuring the residual quantities of HFC-134a in air conditioner of scrap truck. We measured the residual amounts in the scrap truck of 138 by applying commercial recover for refrigerants. The average residual rate(disposal-phase emission factor) is reported to be $44.3{\pm}3.3%$ within a confidence interval of 95%. Recent year model trucks exhibit the higher residual rates. Little variation, however, is observed in regard to vehicle size. The HFC-134a emission quantity from scrap truck in 2011 is estimated to be 55,908 $tCO_2$-eq that demonstrates 21.4% increase to compare with that in 2007. As the numbers of truck have increased dramatically during the last two decades, the emissions of HFC-134a from scrap truck would increase sharply in the next coming years. HFC-134a is a very high GWP greenhouse gas. therefore have to reduce the emissions from the scrap truck and need to find ways to recycle. The chemical compositions of refrigerants from scrap truck are quite similar to those of new refrigerants, suggesting that the refrigerants from scrap truck could be reused as refrigerant.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.733-736
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• 2000

Lignin is usable as fuels and heavy oil additives if depolymerized to monomer unit, because the chemical structures are similar to high octane materials found in gasoline. In this study, the solvent-phase thermal cracking(solvolysis) of lignin was performed at the various temperature and time in a laboratory tubular reactor. Conversion yield was measured for the properties of thermal cracking and liquefaction reaction of lignin. Highest conversion yield when acetone was used as thermal cracking solvent was 55.5% at $350^{\circ}C$, 50minutes and highest tar generation were $260{\sim}350mg/g\;{\cdot}\;lignin$ at $250^{\circ}C$, and highest conversion yield after tar removal was 76.88% at $300^{\circ}C$, 30minutes. Conversion yield, product compositions and amounts were determined by tar degradation yield.

• Journal of the Korean Electrochemical Society
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• v.21 no.1
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• pp.6-11
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• 2018

For the high performance of the secondary battery to satisfy the demands in electronic and energy industries, it is necessary to develop more safe, environmentally friendly and economical electrode. Recently, lithium-sulfur batteries are receiving attention as next-generation secondary cells in terms of its remarkable theoretical capacity, energy density and environmental characteristics. However, they have not yet overcome a fading phenomenon due to the dissolving of the polysulfide. In this study, we intend to fabricate a battery using sulfur, a higher energy density than the other bipolar materials, as an improved secondary cell electrode material. The aim of the study is to improve battery performance with an optimal ratio of the cathode components; such as sulfur of active material and Super P of an electronic conductor.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.583-589
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• 2010

In this paper, the properties of reclaimed ash(RA) from various domestic thermal power plants(S, D and H) were analyzed, and the possibility of fabricating the artificial lightweight aggregate(ALA) using RA was studied. The chemical compositions of RA are similar to the clay, but it had higher concentrations of alkali earth metal oxides(CaO, MgO) and unburned-carbon. The TCLP(Toxicity Characteristic Leaching Procedure) results showed that the dissolution concentrations of heavy metal ions of RA were below the limitation defined by the enforcement regulation of wastes management law in Korea. The results of IC analysis showed that leaching concentration of $Cl^-$ ion was 124 ppm for RA of HN and ${SO_4}^{2-}$ ion was leached a few hundreds ppm for all RA in this study. The ALAs with various mass ratio of clay to reclaimed ash(RA:Clay = 7:3, 6:4, 5:5, 4:6, 3:7) were sintered with a electric muffle furnace at the temperature of $1050{\sim}1200^{\circ}C$. The specific gravity and water absorption(%) of the sintered ALAs were 1.1~1.8 and 10~30% respectively. The ALA sintered in the rotary kiln at $1125^{\circ}C$ showed a bulk density of 1.7 and water absorption of 15.2%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.412-412
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• 2008

ENIG(Electroless Nickel Immersion Gold)is a surface treatment method that is used most widely at fine pitch's SMT and BGA packaging process. ENIG has good diffusion barrier of Ni against solder and good wettability due to Au finish. But when the discoloration occurred on the Au finish of ENIG, some key characteristics related to the quality and reliability of PCB such as bondability, solderability and electrical flowing of packaging process could be deteriorated. In this paper, we have performed the water dip test ($88^{\circ}C$ purified water) which accelerates the galvanic corrosion of Ni diffused from the Ni-P layer. That is, the excessive oxidation of the Ni layer could result in non-wetting of the solder because the flux may not be able to remove excessive oxides. Though Au discoloration have been reported to be caused by Ni oxides in many literature, it is still open to verify and discuss The microstructures and chemical compositions have been investigated using FE-SEM, TEM, FIB, EDS and XPS. As a result, authors have found that the Au discoloration in ENIG type is severely caused by the oxidation of the Ni and the mechanism of Au discoloration can be confirmed through the experiment result of water dip test.

• Korean journal of applied entomology
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• v.57 no.3
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• pp.199-207
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• 2018

Miticidal and repellent activity of twenty plant essential oils against the adults of two spotted spider mites, Tetranychus urticae, were examined. Sandal wood oil was the most potent one in mortality, whereas clary sage oil exhibited the greatest repellent activity. On those twenty essential oils tested, no apparent correlation between toxicity and repellency was observed. When the most active oils were blended, the combinations tend to exhibit antagonistic interactions in both toxicity and repellent activity. The chemical compositions of sandal wood oil and clary sage oil were identified via GC/MS analyses, and the major constituents of sandal wood oils were sesquiterpene compounds, whereas the major ones for clary sage oil were monoterpenes. Among the major components in clary sage oil, linalyl acetate was not only the most abundant constituent, but also the most responsible one for its repellent activity.

• Journal of Korea Foundry Society
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• v.33 no.1
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• pp.13-21
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• 2013

The effects of rare earth element (R.E.) and cooling rate on the eutectic reaction of flake graphite cast irons were studied by combined analysis of macro/micro-structure and cooling curve data. The correlation between eutectic reaction parameter and macro/micro-structure was systematically investigated. Two sets of chemical compositions with the different addition of R.E. were designed to cast. Three types of molds for cylindrical specimens with the different diameters were prepared to analyze cooling rate effect. The difference between undercooling temperature and cementite eutectic temperature (${\Delta}T_1=T_{U}-T_{E,C}$), which is increased by adding R.E. and decreased by increasing cooling rate, is considered to be a suitable eutectic reaction parameter for predicting graphite morphology. According to the criterion, A-type graphite is mainly suggested to form for ${\Delta}T_1$ over $20^{\circ}C$. Eutectic reaction time (${\Delta}t$), which is decreased by adding R.E. or increasing cooling rate, is a suitable eutectic reaction parameter for predicting eutectic cell size. Eutectic cell size is found to decrease in a proportion to the decrease of ${\Delta}t$.

• Journal of Life Science
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• v.18 no.11
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• pp.1538-1542
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• 2008

This study was carried out to investigate the effect of wine ripening on quality characteristics such as chemical compositions, Hunter's color, rheological properties, water activity, pH, TBARS value, VBN content, total plate count and sensory score. Beef jerky was prepared by three types such as beef jerky containing water 50 ml (T0), beef jerky containing water 25 ml and wine 25 ml (T1), and beef jerky containing wine 50 ml (T2). The moisture, crude protein, crude fat, crude ash, $L^*$ (lightness), $a^*$ (redness), $b^*$ (yellowness), hardness, springiness, cohesiveness, gumminess and chewiness were not significantly different among the beef jerky. The Aw, pH and TBARS value were not significantly different among the beef jerky, the VBN content and total plate count of T2 had the lowest among the beef jerky (p<0.05). The flavor of T2 was superior to the T0 (p<0.05), and the taste, color, tenderness, juiciness and overall acceptability were not significantly different among the beef jerky.

• Clean Technology
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• v.20 no.3
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• pp.314-320
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• 2014

The purpose of this work is to optimize composition of mixture refrigerants used in the C3MR (Propane & Mixed Refrigerants) process by a statistical optimization technique. C3MR studied in this work is one of widely used commercial natural gas liquefaction processes with high efficiency. Process simulation was performed in a commercial process simulator and methane ($C_1$), ethane ($C_2$), propane ($C_3$), and nitrogen ($N_2$) were selected as mixed refrigerants. Using the process model, optimum composition of refrigerants mixture was determined via mixture design and central composite design to produce minimum energy consumption. As a result, it was confirmed that energy consumption is reduced down to 11.3% comparing to existing design. It was also compared with heat effectiveness through temperature profile of MCHE (main cryogenic heat exchanger).