• 대한기계학회논문집
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• 제16권6호
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• pp.1150-1155
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• 1992

본 연구에서는 제철소 열연공정의 냉각효율 개선을 위한 기초연구로 수행되었 다. 전열면의 초기온도가 900.deg. C이상일 때 층류 냉각방식에 의한 고온강판의 냉각특 성에 영향을 주는 모든 인자를 엄밀히 고려하는 것은 매우 어려운 일이다.따라서 본 연구에서는 노즐과 고온면 사이 거리(L), 유량(Q), 냉각 초기온도 등을 실제 작업 조건에 가깝게 변화시켜 가면서 수냉반경의 변화를 중심으로 전열면의 냉각 특성을 해 석하였다.

• Journal of Biosystems Engineering
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• 제31권5호
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• pp.430-435
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• 2006

Greenhouse horticulture in South Korea covered about 52,000 ha in 2005. Greenhouse area of about 12,000 ha has been heated during winter season with heating cost of $20{\sim}40%$ of total Production cost. Farmers engaged in greenhouse horticulture were changed into aged people. Therefore the laborsaving of working process and the saving of greenhouse heating cost should be accomplished simultaneously to increase income of greenhouse horticulture. The best method for saving of greenhouse heating cost is to install thermal tunnels into greenhouse. Then hot air heaters using fossil fuel should be changed into hot water heaters. In other words air heating using forced convection should be changed into natural convection system. In this research coil tube made of flexible PE pipe was designed as hot water heat exchanger and its heat exchanging characteristics were analyzed. This new heat exchanger has been adopted as a natural convection system for hot water heating of greenhouse horticulture.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2204-2220
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• 2020

An open-pool type research reactor is designed and operated considering the accessibility around the pool top area to enhance the reactor utilization. The reactor structure assembly is placed at the bottom of the pool and filled with water as a primary coolant for the core cooling and radiation shielding. Most radioactive materials are generated from the fuel assemblies in the reactor core and circulated with the primary coolant. If the primary coolant goes up to the pool surface, the radiation level increases around the working area near the top of the pool. Hence, the hot water layer is designed and formed at the upper part of the pool to suppress the rising of the primary coolant to the pool surface. The temperature gradient is established from the hot water layer to the primary coolant. As this temperature gradient suppresses the circulation of the primary coolant at the upper region of the pool, the radioactive primary coolant rising up directly to the pool surface is minimized. Water mixing between these layers is reduced because the hot water layer is formed above the primary coolant with a higher temperature. The radiation level above the pool surface area is maintained as low as reasonably achievable since the radioactive materials in the primary coolant are trapped under the hot water layer. The key to maintaining the stable hot water layer and keeping the radiation level low on the pool surface is to have a stable flow of the primary coolant. In the research reactor with a downward core flow, the primary coolant is dumped into the reactor pool and goes to the reactor core through the flow guide structure. Flow fields of the primary coolant at the lower region of the reactor pool are largely affected by the dumped primary coolant. Simple, circular, and duct type discharge headers are designed to control the flow fields and make the primary coolant flow stable in the reactor pool. In this research, flow fields of the primary coolant and hot water layer are numerically simulated in the reactor pool. The heat transfer rate, temperature, and velocity fields are taken into consideration to determine the formation of the stable hot water layer and primary coolant flow. The bulk Richardson number is used to evaluate the stability of the flow field. A duct type discharge header is finally chosen to dump the primary coolant into the reactor pool. The bulk Richardson number should be higher than 2.7 and the temperature of the hot water layer should be 1 ℃ higher than the temperature of the primary coolant to maintain the stability of the stratified thermal layer.

• 자원환경지질
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• 제40권5호
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• pp.635-649
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• 2007

이 연구에서는 호남지역에 분포하는 5개 온천(죽림, 변산, 지리산, 덕산, 화순)에서 9개 온천시료와 인근의 지하수 시료 3개를 채취하여 수질화학 성분과 안정동위원소 $({\delta}^{18}O,\;{\delta}D,\;{\delta}^{34}S)$ 및 영족기체(He, Ne, Ar) 동위원소 분석을 통하여 온천수의 지화학적 특성, 지화학적 진화, 그리고 황, 헬륨, 아르곤의 기원을 해석하고자 하였다. 호남지역 온천수의 수온은 $23.0{\sim}30.5^{\circ}C$ 범위로 저온형 온천특성을 보이고 pH는 $7.67{\sim}9.98$ 범위로 알카리성의 특성을 보여주었다. 전기전도도는 $153{\sim}746{\mu}S/cm$ 범위로 지역에 따라서 큰 차이를 보여주었다. 온천주변 지하수의 수질특성은 온천수보다 낮은 pH와 전기전도도의 특성을 보여주었다. 온천수와 지하수의 지화학적 성분은 파이퍼도상에서 크게 3개의 유형으로 구분된다($Na-HCO_3$ 유형, Na-Cl 유형, $Ca-HCO_3$ 유형). 온천수의 지화학적 진화과정을 보면 초기에 $Ca-HCO_3$ 유형에서 출발하여 $Ca(Na)-HCO_3$ 유형을 거쳐 $Na-HCO_3$ 유형으로 진화하였으며, 일부 온천수는(JR1)의 경우 pH 9.98의 알카리성으로, $Na-HCO_3$ 유형의 종말점까지 도달하여 지화학적 진화의 최종단계에 도달되었음을 보여준다. 온천수의 산소 및 수소동위원소 조성은 순환수선을 따라 도시되며 지역에 따라 위도효과를 보인다. 황산염에 대한 황동위원소 대부분 화성기원을 보인다. 그러나 JR1 온천은 고염수에서 기원한 것으로 보이는 해양성기원을 보인다. 온천수의 $^3He/^4He$ 비와 $^4He/^{20}Ne$ 비는 $0.0143{\times}10^{-6}{\sim}0.407{\times}10^{-6}$ 범위와 $6.49{\sim}584{\times}10^{-6}$ 범위를 각각 보여주어 대기와 지각성분의 혼합선상에 도시된다. 이는 온천수내 헬륨가스의 대부분이 지각기원임을 의미한다. 죽림온천(JR1)의 경우 맨틀기원의 헬륨가스의 혼합율이 다른 온천에 비해 다소 높은 비율을 보여준다. 이들 동위원소비와 온천수의 pH와는 대체적으로 정의 상관관계가 확인되었다. 아울러 $^{40}Ar/^{36}Ar$비가 $292.3{\times}10^{-6}{\sim}304.1{\times}10^{-6}$ 범위로 대기기원임을 지시한다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.53-59
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• 1995

In a hot water extraction process, the flow pattern of upper region in a storage tank is a major reason of mixing between hot water and cold water. In this study, the temperature distribution in a storage tank was measured to predict the flow pattern of upper region, and the degree of stratification was analysed to the variables dominating a extraction process. And also, it was found that the degree of stratification improved expecially in a low flow rate in case of using modified distributor I(DMI) as a outlet port type.

• 혜화의학회지
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• 제23권1호
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• pp.105-114
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• 2014

Objectives : In this study, the antioxidant activities of the 80% ethanol and hot water extracts of Euphorbia supina Rafinesque were investigated. Methods : We measured total phenol contents, flavonoid contents, 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay. The production of reactive oxygen species was measured in LPS-induced RAW 264.7 cells using flow cytometry system. Results : The content of phenol in the hot water extract was $65.529{\pm}0.462mg/g$ and $126.932{\pm}1.894mg/g$ in the 80% ethanol extract, and that of flavonoid in the hot water extract was $16.063{\pm}0.471mg/g$ and $29.159{\pm}1.963mg/g$ in the ethanol extract. The 80% ethanol extract also showed higher DPPH and ABTS radical scavenging activities ($90.8{\pm}1.0%$ and $92.5{\pm}0.7%$) than the hot water extract ($81.5{\pm}0.5%$ and $91.5{\pm}0.2%$). The production of reactive oxygen species(ROS) was reduced dose-dependently by 80% ethanol and hot water extract at concentration of 1, 10 and $100{\mu}g/m{\ell}$ of RAW 264.7 cells. Conclusion : According to these results, the 80% ethanol extract of Euphorbia supina Rafinesque has a good anti-oxidative effects than the hot water extract. Thus, the 80% ethanol extract of Euphorbia supina Rafinesque may serve as useful natural antioxidants.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.53-59
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• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000kcal/hr, a $0.15m^3$ hot water storage tank for space heating, a evacuated tubular solar collector $3.74m^2$ of aperture area at the $20^{\circ}$ install angle, a $0.3m^3$ hot water storage tank. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• Food Quality and Culture
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• 제2권1호
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• pp.55-60
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• 2008

This study examined the effects of lactic acid spray, hot water spray, or their combined treatment, as well as the effects of acidified sodium chlorite (ASC), for the decontamination of Escherichia coli on beef carcass surfaces using a commercial intervention system. With this system, the effects of 2 or 4% lactic acid (v/v), hot water ($89{\pm}1^{\circ}C$), or their combined treatment, were examined in terms of reducing inoculated E. coli. ASC (266 ppm), which was adjusted to pH 2.5 using acetic acid or citric acid, was applied using a hand-held spray system. When the beef carcasses were treated with 2 or 4% lactic acid for 10.4 s, less than 1 log reductions of inoculated E. coli were observed. A hot water spray treatment for 9.8 s resulted in a 2.1 log reduction of inoculated E. coli. However, when the hot water was followed with either 2 or 4% lactic acid, no difference in E. coli reduction was found between the hot water alone or the combined treatment with lactic acid. When ASC was adjusted to pH 2.5 with acetic acid and citric acid, 3.8 and 4.1 log reductions of E. coli were observed, respectively. Overall, the lactic acid spray treatment was least effective, and the ASC treatment was most effective, for the E. coli decontamination of beef carcasses. Therefore, these data suggest that ASC would be a more effective intervention against E. coli than most of the methods currently being used. However, more research is required to evaluate the effects of ASC on other organisms, as well as to identify application methods that will not affect meat quality.

• 한국식품과학회지
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• 제27권5호
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• pp.757-761
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• 1995

밥의 텍스쳐에 대한 일련의 연구에서 식미와 관련성이 있는 열수 가용성 쌀 전분에 대하여 분자 구조적 측면에서 그 관련성을 구명하고자 하였다. 열수 가용성 쌀 전분의 분자 구조는 분자 크기가 작은 아밀로오스와 평균 사슬길이 $10{\sim}20$ 글루코오스 단위로 된 아밀로펙틴이 7 : 3 정도로 결합하고 있었다. 열수 가용성 쌀 전분의 용출율은 아밀로오스의 분자 크기가 작을수록, 아밀로펙틴의 초장쇄가 적을수록 높았으며, 전분의 열수 가용화는 전분의 분자 구조와 밀접한 관계가 있었다. 또한, 밥의 텍스쳐는 열수 가용성 쌀 전분의 용출율이 높을수록 경도는 낮고, 부착성은 높았다. 이러한 결과들로 볼때, 밥의 텍스쳐는 쌀 전분의 분자 구조와 밀접한 관계가 있음을 알 수 있었으며 전분의 열수 가용화 되는 성질은 쌀의 식미 평가 지표로서의 가능성이 시사되었다.

• 한국식품과학회지
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• 제27권4호
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• pp.631-634
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• 1995

계통이 다른 쌀 전분(일반계 3품종, 통일계 3품종)에서 열수 불용성 전분을 분리하고 그 전분의 구조적 성질을 조사하였다. 열수 불용성 전분의 아빌로오스 함량은 $2.7{\sim}6.1%$였다. 열수 불용성 전분의 사슬 분포는 ${\overline{DP}}\;55$ 이상의 부분이 $31.9{\sim}38.7%$, ${\overline{DP}}\;40{\sim}55$ 부분이 $12.3{\sim}18.0%$ 그리고 ${\overline{DP}}\;10{\sim}20$ 부분이 $48.5{\sim}50.4%$로서 각 품종별로 차이를 보였으며, ${\beta}$-한계 덱스트린의 분자 크기도 품종에 따라 차이를 보였다. 쌀의 열수 불용성 아밀로펙틴 분자 구조는 쌀 아밀로펙틴의 것과는 서로 달랐다. 이러한 결과는 쌀 전번의 열수 불용화는 각 품종에 따라 그 특성을 보이고, 아밀로펙틴의 분자 구조에 영향을 받고 있음을 알 수 있었다.