• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.315-321
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• 2017

A combustion chamber is designed and fabricated for studying the combustion characteristics of counterflow flames at elevated pressure and establishing the fundamental combustion database of counterflow flames. The combustion chamber design aims to allow the maximum operating pressure of 11 bar and be able to conduct flame visualization and the measurements of flame extinction limits, flame temperature and combustion emissions at elevated pressure. Preliminary tests for counterflow nonpremixed $CH_4-NH_3-N_2$/air flames at 1-3 bar have been conducted, and the results confirm the proper operation of the designed chamber.

• 한국한의학연구원논문집
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• 제9권1호
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• pp.157-178
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• 2003

Objective : This study was designed to assess the protective effects of Chengwhabosimtang on the animal model of depression, chronic mild stress(CMS). Method : Male Sprague-Dawley rats Were used for this experiment. The subjects Were divided into 3 groups (1. CMS-drug: Chengwhabosimtang administered during CMS treatment, 2. CMS-vehicle: water administered, 3. normal ). After 4 weeks of CMS treatment they were executed Forced swimming test(FST) and Elevated plus maze. Tyrosine hydroxylase(TH) in ventral tegmental area(VTA) and c-Fos in paraventricular nucleus(PVN) were measured. Result : 1. In FST, CMS-drug group showed significantly decreased immobility behavior. 2. CMS-drug group showed no significantly lower TH level in VTA than CMS-vehicle group. 3. CMS-drug group showed significantly less c-Fos expressed cell bodies in PVN than CMS-vehicle group. 4. In Elevated plus maze, CMS-drug group showed no significantly anxiety. Conclusion : These results suggest that Chengwhabosimtang may have protective antidepressant effects in CMS model rats. And these effects could be explained by the elevated stress-copying behaviors which are related with PVN of hypothalamus and dopaminergic neurons in VTA.

• 한국추진공학회지
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• 제12권5호
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• pp.35-42
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• 2008

본 연구는 AISI 304강의 상온 및 고온 인장실험을 수행한 결과이다. 항공구조재료로 널리 사용되고 있는 AISI 304강의 인장실험을 ASTM 규정에 따라 상온 및 고온에서 수행하였다. A Basis와 B Basis 인장강도를 평가하기 위하여 정규확률지를 사용하였다. 응력과 소성변형률과의 관계를 지수함수로 가정하는 Ramberg-Osgood 파라미터는 시험데이터의 최소제곱추정을 이용하여 구하였다. 인장실험 후 시험편의 표면을 SEM 영상과 EDX를 사용하여 관찰하였다.

• 소성∙가공
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• 제19권4호
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• pp.230-235
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• 2010

Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only for aerospace parts but also for bio prothesis and motorcycle. However, the database is insufficient in the titanium alloy for press forming process. In this study, the effect of temperature on the forming limit diagram was investigated for Ti-6Al-4V titanium alloy sheet through the Hecker‘s punch stretching test at elevated temperature. Experimental results obtained in this study can provide a database for the development of press forming process at elevated temperature of Ti-6Al-4V titanium alloy sheet. From the experimental studies it can be concluded that the formability of Ti-6Al-4V titanium alloy sheet is governed by the ductile failure for the testing temperature. The formability of Ti-6Al-4V titanium alloy sheet at $700^{\circ}C$ increases about 7 times compared with that at room temperature.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1255-1260
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• 2008

This study is simulation of high elevated liquid line of a modular heat pump system to observe longitudinal subcooling variation. In a high elevated tube, subcooled refrigerant(R410A) through a condenser changes its states by heat transfer with surrounding air and by pressure drop from elevation. In this study, the liquid line was simulated through correlations of heat transfer and pressure drop for the variation from single-phase into two-phase flow. Pressure drop, heat transfer rate and vapor quality were calculated as key parameters. Two-phase turning heights and variations of the key parameters were confirmed from the simulation. As a result, high elevation of liquid line has great influence on upward flow, which requires additional equipment to compensate the variation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.152-157
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• 2009

Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only aerospace parts but also bio prothesis and motorcycle. But the database is insufficient of the titanium alloy for press forming process. In this study, the effect of temperature on the forming limit diagram was investigated for Ti-6Al-4V titanium alloy sheet through the Hocker's punch stretching test at elevated temperature. Experimental results obtained in this study can provide a database for development of press forming process at elevated temperature of Ti-6Al-4V titanium alloy sheet. From the experimental studies it can be concluded that the formability of Ti-6Al-4V titanium alloy sheet is governed by the ductile failure for the testing temperature below and vice versa neck-induced failure above the recrystalization temperature $0.5T_m$. The formability of Ti-6Al-4V titanium alloy sheet at $750^{\circ}C$ increases about 7 times compared with that at room temperature.

• Journal of Ginseng Research
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• 제28권3호
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• pp.132-135
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• 2004

This study was performed to investigate the anxiolytic effects of total sponin fraction from Ginseng Radix Rubra (KRG) in mice using the elevated plus-maze model. The water extract of KRG and ginseng total saponins (GTS) purified from the water extract of KRG were administered orally to mice. One hour after administration of KRG water extract and GTS, mice were tested on the elevated plus-maze. The water extract of KRG 100 mg/kg, and GTS 25 and 50 mg/kg did not increase open arm entries and time spent on open arm. However, GTS 100 mg/kg increased the number of open arm entries and time spent on open arm. On the other hand, as the plus-maze test was affected by changes in locomotor activity, an additional test was carried out with the specific aim of monitoring locomotor activity. The water extract of KRG 100 mg/kg, and GTS 25 and 50 mg/kg did not affect the locomotor activity. However, GTS 100 mg/kg significantly decreased locomotor activity. From this study, we suggest that GTS may play an imponant role on the anxiolytic effects in the plus-maze model.

• 한국임상약학회지
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• 제3권1호
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• pp.45-53
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• 1993

Biphenyl Dimethyl dicarboxylate(DDB) has been regarded as a safe, effective drug for decreasing serum aminotransferase levels from elevated serum aminotransferase levels, which cause acute or chronic hepatitis and chronic liver diseases. This study was designed to low dose(22.5mg/day) & short-term therapy effectiveness for 4 weeks of DDB in 30 chronic hepatitis patients with elevated serum aminotransferases. The following results were observed. 1. Serum alanine aminotransferase(ALT) levels significantly decresed from 173. $97\pm130.62(U/L)$ of pretreatment level to $32.23\pm19.22(U/L)$ after treatment for 4 weeks(p<0.00l) and normalized patients by $73\%$ 2. Serum aspartate (AST) aminotransferase levels significantly decreased from $94.90\pm49.17(U/L)$ of pretreatment level to $45.30\pm23.25(U/L)4 after treatment(p0<0.01). 3. However, no significant effects in the serum AST & ALT changes by which cause hepatitis and hepatitis duration (p>0.05). 4. No significant adverse effects were observed except for mild epigastric discomfort in one patient during DDB treatment It is suggested that DDB small dosage administration can result effectively decreasing serum aminotransferase levels from chronic hepatitis patients with elevated serum aminotransferase levels.

• Advances in concrete construction
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• 제10권2호
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• pp.113-125
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• 2020

This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

• 국제초고층학회논문집
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• 제2권2호
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• pp.115-121
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• 2013

The ventilation performance of a street in Bangkok, Thailand, was investigated by performing measurements and conducting a CFD analysis. We focused on a street that was covered by an elevated train station. It was shown that the ventilation efficiency varied drastically depending on the angle between the street and the wind direction. When the wind direction was parallel to the street, the elevated structure had a negative influence, which created higher pollutant concentrations than in locations without elevated structures. However, when the wind direction was perpendicular to the street, the pollutant concentrations in the two situations were similar. Using a CFD analysis and ventilation performance indexes, it was shown that the elevated structure directed the wind flow and enhanced the ventilation efficiency, which positively affected ventilation performance. These kinds of knowledge can lead us to optimize city planning including high-rise buildings with high ventilation efficiency.