• Fire Science and Engineering
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• v.30 no.3
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• pp.16-22
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• 2016

Fire fighters rely on fire fighter protective clothing (FFPC) to provide adequate protection in the various hazardous environments. To enhance its protection performance, the FFPC material must be thick and thus it is difficult to achieve weight reduction. One of the methods of overcoming this problem, the addition of phase change material (PCM) to FFPC, is a new technology. In previous studies, the researches was mostly related to the temperature characteristics of the fibers incorporating PCM, but little information is available about its effect on burn injuries. Thus, in this study, the inhibitory effects of adding PCM to FFPC on second degree burns were investigated through numerical calculations. Thermal analyses of biological tissues and FFPC with embedded PCM exposed to several fire conditions causing severe tissue damage were studied by using a finite difference method based on the Pennes bio-heat equation. FFPC with embedded PCM was found to provide significantly greater protection than conventional fire fighting clothing, because the heat of absorption due to the phase change within the material is used to limit the heat conduction of the material.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.767-773
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• 2010

This paper describes development of a non-explosive separation device which can be equipped on small satellites. The spur geared micro DC motor, which has high reliability and advantage of price, is adopted as an actuator. The proposed separation device has resettability and it does not need extra jig to reload. In addition, the simple structure makes it easy to fabricate and assemble. To verify the performance of the proposed device, the response time tests, maximum preload tests and maximum shock level tests were performed. Also, through the vibration tests and thermal vacuum tests, feasibility of the proposed separation device was shown in launching and space environments. Therefore, we expect that the proposed separation device can replace the imported separation devices in near future.

• Economic and Environmental Geology
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• v.22 no.3
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• pp.237-252
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• 1989

The Inseong gold-silver mine is located 3Km northwest of Suanbo, Choongcheongbugdo, Republic of Korea. The mine occurs in the shear zone formed by tension fractures within the Hwanggangri Formation of the Ogcheon metamorphic belt. Ore minerals found in the gold-silver bearing hydrothermal quartz vein composed mainly of pyrite, arsenopyrite, sphalerite, galena and minor amount of chalcopyrite, pyrrhotite, stannite, bismuthininte, native bismuth, chalcocite, electrum and tellurian canfieldite(?). The gangue minerals are quartz, calcite, chlorite and rhodochrocite. Wallrock alterations such as chloritization, silicitication, pyritization, carbonitization and sericitization can be observed in or around the quartz vein. According to the paragenetic sequence, quartz vein structure and mineral assemnlages, three different stages of ore formation can be recognized. The physico-chemical environment of ore formation in this deposit shows slight variation from stage to stage, but the condition of main ore deposition can be summarized as follows. Fluid inclusion, S-istope geothermometry and geothermometry based on mineral chemistry by use of arsenopyrite and chlorite show the ore was formed at temperature between 399 and $210^{\circ}C$ from fluids with salinities of 3.3-5.8 wt.% equivalent NaCl. It indicates that pressure during the mineralization is less than 0.6 Kb corresponding to a depth not greater than 1Km. S-isotope data suggests that thermal fluid may have magmatic origin wit some degree of mixing with meteoric water. In coclusion, the Inseong gold-silver deposit was formed at shallow depth and relatively high-temperature possibly with steep geothermal gradient under xenothermal condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.758-765
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• 2016

This paper is a follow-up paper to the publication, "Development of Tunnel-Environment Monitoring System and Its Installation I - Monitoring System and Measurement in Subway Tunnel" [1]. An environment monitoring system was installed in the 20.3-km-long Gumjung tunnel, which has the general structure of a high-speed double-track railway tunnel. Data were collected for approximately one year. Monthly and daily data were obtained and analyzed for the temperature and relative humidity in summer and winter months. This paper discusses the environmental characteristics at different positions in the tunnel. The results are expected to be widely used in studies on tunnel ventilation and the improvement of air quality and thermal environments.

• Journal of Animal Science and Technology
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• v.51 no.6
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• pp.527-536
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• 2009

A potent protein degrading bacterium was isolated from soil samples of different environments. Polyphasic taxonomic studies and phylogenetic 16S rRNA sequence analyses led to identify the isolate IB No. 11 as a strain of Bacillus subtilis. The isolated strain was recognized to produce protease constitutively, and the maximum production (1.64 units/ml) was attained in a shake flask culture when the isolate was grown at $40^{\circ}C$, for 32 h in basal medium supplemented with starch (0.25%) and gelatin (1.25%) as sole carbon and nitrogen source, respectively. The optimum pH and temperature for the protease activity were determined to be pH 7.0 and $50^{\circ}C$, respectively. $Ca^{2+}$ and $Mn^{2+}$ enhanced remarkably the protease activity but neither showed positive effect on the protease's thermal stability. In addition, it was observed that the protease was fairly stable in the pH range of 6.5-8.0 and at temperatures below $50^{\circ}C$, and it could be a good candidate for an animal feed additive. The inhibition profile of the protease by various inhibitors indicated that the enzyme is a member of serine-proteases. A combination of UV irradiation and NTG mutagenesis allowed to develop a protease hyper-producing mutant strain coded as IB No. 11-4. This mutant strain produced approximately 3.23-fold higher protease activity (6.74 units/mg) than the parent strain IB No. 11 when grown at $40^{\circ}C$ for 32h in the production medium. The protease production profile of the selected mutants was also confirmed by the zymography analysis.

• Animal cells and systems
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• v.15 no.3
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• pp.219-225
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• 2011

We studied oxidative stress in cinnamon clownfish exposed to hypoosmotic (35 psu ${\rightarrow}$ 17.5 psu and 17.5 psu with prolactin (PRL)) and low temperature ($28^{\circ}C{\rightarrow}24^{\circ}C$ and $20^{\circ}C$) conditions by measuring the expression and activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD), catalase (CAT), and glutathione peroxidase (GPX). The expression and activity of the antioxidant enzymes were significantly higher after the fish were exposed to $24^{\circ}C$, $20^{\circ}C$, and 17.5 psu, and expression was repressed by PRL treatment. Furthermore, we measured $H_2O_2$ and lipid peroxidation levels and found that they were significantly higher after exposure to the hypoosmotic and low-temperature environments. Additionally, we investigated changes in plasma AST and ALT levels after exposure to low temperature and hypoosmotic stress. These levels increased upon exposure of the clownfish to $24^{\circ}C$, $20^{\circ}C$, and 17.5 psu, but the levels of these parameters decreased in the 17.5 psu with PRL treatment during a salinity change. The results indicate that hypoosmotic and low-temperature conditions induce oxidative stress in cinnamon clownfish and that the parameters tested in this study may be indices of oxidative stress in the cinnamon clownfish.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.219-226
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• 2012

This study provides an analysis on results of neutron logging for various borehole environments through numerical simulation based on a Monte Carlo N-Particle (MCNP) code developed and maintained by Los Alamos National Laboratory. MCNP is suitable for the simulation of neutron logging since the algorithm can simulate transport of nuclear particles in three-dimensional geometry. Rather than simulating a specific tool of a particular service company between many commercial neutron tools, we have constructed a generic thermal neutron tool characterizing commercial tools. This study makes calibration chart of the neutron logging tool for materials (e.g., limestone, sandstone and dolomite) with various porosities. Further, we provides correction charts for the generic neutron logging tool to analyze responses of the tool under various borehole conditions by considering brine-filled borehole fluid and void water, and presence of borehole fluid.

• Journal of IKEEE
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• v.24 no.1
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• pp.284-292
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• 2020

SiC-based devices perform well in high-voltage environments of more than 1200V compared to silicon devices, and are particularly stable at very high temperatures. Therefore, 1700V UMOSFET has been actively researched and developed for the use of electric power systems such as electric vehicles and aircrafts. In this paper, we analysed thermal variations of critical variables (breakdown voltage (BV), on-resistance (R_on), threshold voltage (v_th), and transconductance (g_m)) for the three type 1700V UMOSFETs-Conventional UMOSFET (C-UMOSFET), Source Trench UMOSFET (ST-UMOSFET), and Local Floating Superjunction UMOSFET (LFS-UMOSFET). All three devices showed BV increase, R_on increase, v_th decrease, and g_m decrease with increasing temperature. However, there are differences in BV, R_on, v_th, g_m according to the structural differences of the three devices, and the degree and cause of the analysis were compared. All results were simulated using sentaurus TCAD.

• Journal of the Korean Geotechnical Society
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• v.36 no.8
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• pp.17-25
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• 2020

Korea Institute of Civil Engineering and Building Technology has constructed a large scale Dust Thermal Vacuum Chamber to simulate extreme lunar terrestrial environments and to study the Moon as an outposts for space development and exploration. Although a large amount of KLS-1 (Korean Lunar Simulant-1) is required for research, its massive production is practically difficult. This paper describes semi-automatic manufacturing system for massive production of KLS-1 in detail, which is seven times more efficient than manual production. In addition, to increase the similarity with lunar regolith, hydrogen reduction reaction using ilmenite which is one of the minerals was also conducted to simulate nanophase Fe(0) which is the unique property of lunar regolith. As a result, it was found that np-Fe(0) was formed at a temperature of 700℃ or higher, and increased in proportion to the temperature until 900℃.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.569-578
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• 2011

The $SiO_2$ membranes for polymer electrolyte membrane fuel cell (PEMFC) are preapared by electrospinning method. It leads to high porosity and surface area of membrane to accommodate the proton conducting materials. The composite membrane was prepared by impregnating of Nafion ionomer into the pores of electrospun $SiO_2$ membranes. The $SiO_2$:heteropolyacid (HPA) nano-particles as a inorganic proton conductor were prepared by microemulsion process and the particles are added to the Nafion ionomer. The characterization of the membranes was confirmed by field emission scanning electron microscope (FE-SEM), thermogravimetry analysis (TGA), and single cell performance test for PEMFC. The Nafion impregnated electrospun $SiO_2$ membrane showed good thermal stability, satisfactory mechanical properties and high proton conductivity. The addition of the $SiO_2$:HPA nano-particle improved proton conductivity of the composite membrane, which allow further extension for operation temperature in low humidity environments. The composite membrane exhibited a promising properties for the application in high temperature PEMFC.