• 한국산학기술학회논문지
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• 제21권8호
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• pp.298-303
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• 2020

본 연구는 고품질의 천일염을 생산하기 위한 세정조건을 구명하기 위해서 수행되었다. 세정시 수율의 감소를 방지하기 위해서 세정수의 염도는 5 %로 설정하였고, 온도조건은 5, 10, 17.5, 20 ℃로 총 4가지 수준이었다. 세정 실험 후 수분, 염도, 불용분, 사분의 함량을 측정하였다. Color 특성으로는 L*[lightness], a*[redness], b*[yellowness]값을 측정하였고, 최종적으로 수율을 측정하였다. 세정 후 천일염의 수분은 세정수의 온도가 10 ℃이상의 범위에서 증가하는 경향을 나타내었다. 염도와 수율은 세정수의 온도가 높을수록 감소하였고, 불용분의 함량은 세정수의 온도가 낮을수록 감소하는 것으로 나타났다. 사분의 함량은 세정수의 온도가 5 ℃인 경우 0.67 %이었고, 더 높은 온도에서는 0.57 %로 감소하였다. 색도중 b*값의 경우에는 세정수의 온도가 높을수록 높게 나타났으며, 이는 표면품질 저하의 원인으로 판단되었다. 따라서, 품질 저하와 수율의 감소를 최소화하는 세정수의 온도는 10 ℃이상이 적합한 것으로 나타났다. 향후 세정 후 건조조건 구명을 위한 실험을 수행하여 최적의 고품질 생산 공정의 설계인자를 도출할 수 있을 것으로 기대된다.

• 한국지열·수열에너지학회논문집
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• 제3권2호
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• pp.17-23
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• 2007

Geothermal energy is used in various forms, such as power generation, direct use, and geothermal heat pumps. High temperature geothermal energy sources have been used for power generation for more than a century. Recent technical advances in power generation equipments make relatively low temperature geothermal energy to be available for power generation. In these applications, lower temperature geothermal energy source makes smaller difference between condensing water temperature and it. Various condensing water temperatures were investigated in analyzing its influence on power generation performance. Condensing water temperature of organic Rankine cycle imposed greater influence on power generation and its performance in lower temperature geothermal power generation.

• 방사성폐기물학회지
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• 제20권2호
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• pp.185-192
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• 2022

A compacted bentonite buffer is a major component of engineered barrier systems, which are designed for the disposal of high-level radioactive waste. In most countries, the target temperature required to maintain safe functioning is below 100℃. If the target temperature of the compacted bentonite buffer can be increased above 100℃, the disposal area can be dramatically reduced. To increase the target temperature of the buffer, it is necessary to investigate its properties at temperatures above 100℃. Although some studies have investigated thermal-hydraulic properties above 100℃, few have evaluated the water suction of compacted bentonite. This study addresses that knowledge gap by evaluating the water suction variation for compacted Korean bentonite in the 25-150℃ range, with initial saturations of 0 and 0.22 under constant saturation conditions. We found that water suction decreased by 5-20% for a temperature increase of 100-150℃.

• Journal of Microbiology and Biotechnology
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• 제4권4호
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• pp.316-321
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• 1994

We investigated the possibility of industrial application and economit process of high temperature fermentation by thermotolerant alcohol producing yeasts as previously reported. From the 20% glucose media, the RA-74-2 produced 11.8% (v/v) ethanol at $32^{\circ}C$ (0.5% inoculum) and 10.6% (v/v) ethanol at $40^{\circ}C$ (3% inoculum), respectively. Also, 11.3% (v/v) ethanol was produced for 96 hours in the temperature-gradient fermentation. These results suggest that the RA-74-2 could isuccessfully be applied to save the cooling water and energy in industrial scale without re-investment or modification of established fermentation systems. When potato starch was used as the substrate for the RA-74-2, high temperature fermentation above $40^{\circ}C$ was more appropriate for industrial utilization because organic nitrogen was not necessary to economical fermentation. As the naked barley media just prior to industrial inoculation, taken from the Poongkuk alcohol industry Co., were used, 9.6% (v/v) ethanol was produced at $40^{\circ}C$ for 48 hours in jar-fermentor scale (actually, 9.5-9.8% (v/v) ethanol was produced at 30~$32^{\circ}C$ for 100 hours in industrial scale). The ethanol productivity was increased by the high glucoamylase activity as well as the high metabolic ratio at $40^{\circ}C$ Therefore, if the thermotolerant yeast RA-74-2 would be used in industrial scale, we could obtain a high productivity and saving of the cooling water and energy. Meanwhile, the RA-912 produced 6%(v/v) ethanol in 10% glucose media at $45^{\circ}C$ and showed the less ethanol-tolerance compared with industrial strains. As the produced alcohol was recovered by the vacuum evaporator at $45^{\circ}C$ in 15% glucose media, the final fermentation ratio was enhanced (76% of theoretical yields). This suggest that a hyperproductive process could be achieved by a continuous input of the substrate and continuous recovery of the product under vacuum in high cell-density culture.

• 한국물환경학회지
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• 제28권5호
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• pp.646-656
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• 2012

This study area was Saemangeum Reservoir in Korea and the applied model was Environmental Fluid Dynamics Code(EFDC). It was the same as the scenarios to the boundary and initial conditions except the resolutions of the model grids. The resolutions were about 800 and 2,000 cells. It was considered scenario 1 and 2. The model was performed to simulate the water temperature, salinity, water quality parameters such as dissolved oxygen(DO), chemical oxygen demand(COD), total nitrogen(T-N), and total phosphorus(T-P) at 2008. The simulation results of the two scenarios were reflected in the trend of observed data tolerably. However, water flow, water temperature, and salinity showed high confidence level at the scenario 1. The water quality items did not present high confidence level at the scenario 1 because which concept was considered to biochemical and physical processes. This result shows that grid resolution has an influence on the water transport and the effect is reflected directly shallow and narrow water area. But, the selection of grid resolution should be considered the purpose of model simulation and the process of target items.

• 한국해안해양공학회지
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• 제19권3호
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• pp.213-221
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• 2007

전지구적으로 지구 온난화 문제가 대두되고 있는 현 상황에서, 기온변화에 수반되는 수온변화 반응을 파악하기 위하여 해양수산부에서 제공하는 마산만 연안해역의 기온 및 수온 관측자료를 이용하여 기온과 수온의 관계를 분석하였다. 수온과 기온의 무차원 자기상관함수와 교차상관함수 변화를 분석한 결과, 지체시간 10일 이내에서는 상관계수가 0.9 이상으로 매우 크게 나타났으며, 지점별로 수온의 상관계수보다 기온의 상관계수가 크게 나타나는 것으로 파악되었다. 마산만 기온 및 수온자료를 수온상승기, 수온하강기로 구분하여 분석한 결과, 수온상승기에는 MA1 지점, MA2 지점의 기울기가 각각 0.829, 0.774로 나타났으며, 수온하강기에는 MA1 지점, MA2 지점의 기울기가 각각 1.385, 1.444로 기온상승기에 비하여 기온하강기의 기울기가 약 1.75배 정도 크게 나타나고 있으며, 명확한 이력현상으로 파악되었다. 따라서, 마산만 연안해역의 기온-수온 상관관계를 보다 정확하게 결정하기 위해서는 기온-수온의 계절적인 이력현상을 포함하여야 하며, 이 경우 기온을 이용한 수온 추정결과의 정확도가 향상되는 것으로 파악되었다.

• Computers and Concrete
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• 제19권2호
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• pp.121-126
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• 2017

This paper presents the effect of aggregate type on high temperature resistance of self-compacting mortars (SCM) produced with normal and lightweight aggregates like expanded perlite and pumice. Silica fume (SF) and fly ash (FA) were used as mineral additives. Totally 13 different mixtures were designed according to the aggregate rates. Mini slump flow, mini V-funnel and viscometer tests were carried out on the fresh mortar. On the other hand, bulk density, porosity, water absorption and high temperature tests were made on the hardened SCM. After being heated to temperatures of 300, 600 and $900^{\circ}C$, respectively, the tensile strength in bending and compressive strength of mortars determined. As a result of the experiments, the increase in the use of lightweight aggregate increased total water absorption and porosity of mortars. It is observed that, the increment in the usage of lightweight aggregate decreased tensile strength in bending and compressive strengths of mortar specimens exposed to high temperatures but the usage of up to 10% expanded perlite in mortar increased the compressive strength of specimens exposed to $300^{\circ}C$.

• 한국패류학회지
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• 제29권3호
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• pp.245-250
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• 2013

We investigated the factors of mass-mortality in terms of water temperature and prey, in order to prevent the mass-mortality of cultured oysters at Gamak Bay in Yeosu City in 2007. The real-time water temperature was recorded as high, 28 to 31C, during late August. Nutrients, Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphate (DIP) were downed in September. The analyzed results of chlorophyll a content were 0.78-1.50 ${\mu}gL^{-1}$ and phytoplankton for food resources was 81 cells $mL^{-1}$, both were low. The finding here indicate that Gamak Bay is in an oligotrophic state. The mass-mortality of cultured oysters occurred 43.6% in Gamak Bay. The mortality rate of oyster were above 67.0%, at Wanpo, however, it was showed 18.3% at Gumchun. Therefore, we believe the mass-mortality of cultured oysters at Gamak Bay comes from the destruction of bio-rhythms due to high water temperature and quantitatively and qualitatively decreasing food resources due to the limitation of nutrients.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.264-265
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• 2008

While the reliability of bulk insulation has become important particularly in multilayer boards and embedded boards, electronics are to be used under various environments such as at high temperature and in high humidity. We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

• 설비공학논문집
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• 제15권8호
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• pp.690-696
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• 2003

This paper presents the heat recovery performance of water fluidized-bed heat exchanger. Temperature and humidity ratio of waste gas are considered as important parameters in this study. Therefore, the heat recovery rate through water fluidized-bed heat exchanger for exhaust gases with various temperatures and humidity ratios can be estimated from the results of this study. Mass flow ratio (the ratio of mass flow rate of water to that of gas) and temperature of inlet water are also considered as important operating variables. Increase of heat recovery rate can be obtained through either high mass flow ratio or low temperature of inlet water with resultant low recovered temperature. The heat recovery performance with the mass flow ratio of about up to 10 has been investigated. The effect of number of stages of water fluidized-bed on the heat recovery performance has been also examined in this study.