• Nuclear Engineering and Technology
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• 제52권2호
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• pp.248-257
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• 2020

This study presents an initial design for a novel system consisting in a coupled nuclear reactor and a phase change material-based thermal energy storage (TES) component, which acts as a buffer and regulator of heat transfer between the primary and secondary loops. The goal of this concept is to enhance the capacity factor of nuclear power plants (NPPs) in the case of high integration of renewable energy sources into the electric grid. Hence, this system could support in elevating the economics of NPPs in current competitive markets, especially with subsidized solar and wind energy sources, and relatively low oil and gas prices. Furthermore, utilizing a prismatic-core advanced high temperature reactor (PAHTR) cooled by a molten salt with a high melting point, have the potential in increasing the system efficiency due to its high operating temperature, and providing the baseline requirements for coupling other process heat applications. The present research studies the neutronics and thermal hydraulics (TH) of the PAHTR as well as TH calculations for the TES which consists of 300 blocks with a total heat storage capacity of 150 MWd. SERPENT Monte Carlo and MCNP5 codes carried out the neutronics analysis of the PAHTR which is sized to have a 5-year refueling cycle and rated power of 300 MW_th. The PAHTR has 10 metric tons of heavy metal with 19.75 wt% enriched UO₂ TRISO fuel, a hot clean excess reactivity and shutdown margin of $33.70 and -$115.68; respectively, negative temperature feedback coefficients, and an axial flux peaking factor of 1.68. Star-CCM + code predicted the correct convective heat transfer coefficient variations for both the reactor and the storage. TH analysis results show that the flow in the primary loop (in the reactor and TES) remains in the developing mixed convection regime while it reaches a fully developed flow in the secondary loop.

• 한국식품위생안전성학회지
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• 제5권4호
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• pp.219-228
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• 1990

생유와 시판되고 있는 저온살균유, 고온 순간살균유 및 초고온순간살균유 각 20예에 대하여 polyacrylamide 겔 전기 영동법으로 단백질의 조성을 구하였다. 생유의 Whey 단백질 중 혈청 albumin, ${\alpha}-lactalbumin,\;{\beta}-lactoglobulin$의 조성은 3.71 : 11.44 : 84.85였으며 저온 살균과 고온순간살균에 의하여 큰 변호를 주지 않았다. 그러나 초고온 순간 살균으로 조성비는 0 : 64.75 : 35.5로 변화되어 형청 albumin의 소실과 ${\beta}-lactoglobulin$의 감소를 보였다. 살균처리유의 냉장보존 3일째에 ${\alpha}-lactalumin과\;{\beta}-lactoglobulin$의 감소가 있었으나 $25^{\circ}C$ 실온보존에서는 변화가 없었다. 고온 순간 살균유는 실온보존 2일째에 혈청 albumin, 3일째에 ${\alpha}-Lactalbumin의$ 감소만 있었고 다른 Whey 단밸질은 보존온도에 관계없이 3일간 농도변화가 없었다. 초고온순간살균유는 냉장보존 2일째 혈청 albumin의 감소만 인정되었다.

• 한국식생활문화학회지
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• 제35권5호
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• pp.450-458
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• 2020

This study examined the optimal temperature and time conditions to maintain high quality Dongchimi during the fermentation and storage period. Dongchimi was fermented at low (5℃), medium (10 and 15℃), and high (20℃) temperatures until the acidity reached 0.2, 0.3, and 0.4%. respectively. From the consumer's preference test enrolling five consumers, Dongchimi fermented at 15℃ until an acidity of 0.3% (for approximately six days) was evaluated to be the optimal status because of its high score of overall acceptance, taste, and odor of consumers. To determine the optimal storage temperature of fermentation, Dongchimi was stored at three different temperatures (-1, 2, 5℃) for four weeks after fermenting at 15℃ for six days. During the storage period, most of the physicochemical properties (pH, acidity, reducing sugar content, and organic acid) and microbiological properties changed significantly in the 2 and 5℃ groups, resulting in a significant change in descriptive sensory analysis of Dongchimi. These results indicate that fermentation at 15℃ and storage at -1℃ for Dongchimi enables it to maintain the best quality for a long time.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.302-305
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• 2007

In recent years, many researches on new storage media with high capacity and information are developing. For manufacture of optical storage with high capacity, the injection molding process is generally used. In order to increase the filling ratio of the injection molding structure, the injection molding process required for high injection pressure, packing pressure and temperature control of the mold. However, conventional injection molding process is difficult to increase the filling ratio using injection master with the range of several nanometers and high aspect ratio. In order to improve and increase filling ratio of nano-structure with high aspect ratio, the active temperature control of injection mold was used. Experimental conditions were used injection pressure, time and temperature. Consequently, by using the peltier device into injection mold, we carried out the efficient and active temperature control of mold at low cost.

• Asian-Australasian Journal of Animal Sciences
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• 제24권2호
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• pp.279-284
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• 2011

The objective of this study was to evaluate the effects of storage temperature and time on the quality parameters of eggs from laying hens at peak production. A total of 576 eggs were obtained from Lohmann Light-Brown hens, which were collected 3 times when the hens were 26, 27, and 28 weeks old. The fresh eggs were collected and measured within 2 h of being laid. Samples of 48 eggs each were stored in chambers for 2, 5, or 10 d inside a refrigerator ($5^{\circ}C$), at room temperature ($21^{\circ}C$), and at a high temperature ($29^{\circ}C$). As the storage temperature and time increased, egg weight, percentage of albumen, Haugh unit (HU), and yolk color significantly (p<0.001) decreased. In addition, egg shell weight, shell percentage, and albumen weight significantly (p<0.001) decreased with storage time. Yolk weight, yolk percentage, and albumen pH significantly (p<0.001) increased with increasing storage temperature, and yolk pH significantly (p<0.001) increased with increasing storage time. When the storage temperature was increased to $29^{\circ}C$, egg weight loss dramatically increased from 1.74 to 3.67% at 5 and 10 d of storage time, respectively. With the exception of the $5^{\circ}C$ storage temperature, HU dramatically decreased according to storage time and temperature, decreasing from 91.3 to 72.63 at $21^{\circ}C$ and from 87.62 to 60.92 at $29^{\circ}C$ during 10 d of storage; however, this decline was not found at $5^{\circ}C$. A rapid increase in albumen alkalinity was observed even after just 2 d of storage regardless of the storage temperature. Interactions between storage time and temperature were significant (p<0.001) with respect to egg weight loss, egg shell weight and percentage, albumen weight and percentage, yolk weight and percentage, albumen and yolk pH, HU, and yolk color. The results of the current study indicated that eggs from laying hens at peak production had significant deterioration of internal quality with increasing storage temperature and time. The results suggest that egg weight loss, albumen pH, and HU are parameters that are greatly influenced by the storage temperature and time of eggs from hens at peak laying.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.190-193
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• 2008

The heat transfer characteristics of molten salt storage system for the solar thermal power generation were investigated. Temperature profiles and the heat transfer coefficients during the storage and discharge stage were obtained with the steam as the heat transfer fluid. Two kinds of inorganic salt were employed as the storage materials and coil type of heat exchanger were installed in both tanks to provide the heat transfer surfaces during the storage and discharge stage. The effects of steam flow rates, flow direction of steam in the storage tank and the initial temperature of storage and discharge tank on the heat transfer were tested.

• 생명과학회지
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• 제25권10호
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• pp.1124-1131
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• 2015

본 연구를 통해 보관 조건에 따른 사물탕 전탕액의 유효활성 물질 및 안정성과 관련된 특성들의 경시적 변화를 관찰하였다. 사물탕 전탕액의 보관온도(냉동 조건, 냉장 조건, 상온 암 조건, 상온 빛 조건, 고온 조건)를 달리하여, 각각을 0, 15, 30, 90, 180일간 보관하였다. 사물탕 전탕액의 경시적 변화로는 육안적 관찰, 산도, 흡광도, high performance liquid chromatography (HPLC) 분석, 생리활성(tyrosinase 저해 활성), 세균학적 검사 등을 관찰하였다. 그 결과, 사물탕 전탕액의 다양한 보관 기간과 온도에서, 육안적 검사, 산도, 흡광도, HPLC분석, 생리활성에서 경시적으로 큰 변화가 없었으며, 세균학적 검사를 통해서는 세균이 검출되지 않았다. 그러나 그 변화의 차이는 크지 않았지만, 사물탕 전탕액의 보관조건이 악화될수록, 보관기간이 증가할수록 미세한 변화가 관찰되었다. 따라서 6개월 이상 장기간 보관 할 경우, 사물탕 전탕액을 상온 암 조건, 상온 빛 조건, 고온 조건에서 보다 냉동 혹은 냉장 조건이나 가능하면 어두운 곳에서 보관하는 것이 유효성분 및 활성의 변화나 전탕액의 변질을 방지하기 위한 보관법으로 판단되었다.

• 한국식품영양과학회지
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• 제27권5호
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• pp.827-832
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• 1998

Soybeans(Hwangkeum Kong) were stored at 5$^{\circ}C$, $25^{\circ}C$ and 35$^{\circ}C$ for 8 months to investigate the changes of the physicochemical properties. Less physicochemical changes were detected in the soybeans stored at 5$^{\circ}C$ than those stored at $25^{\circ}C$ and 35$^{\circ}C$. High temperature and long term storage caused a decrease in the nitrogen solubility index, whereas increases in acid value and organic acid content were detected. As the storage period was extended at high temperatues, the content of unsaturated fatty acids decreased, but the content of saturated fatty acids increased. Decoloration of soybeans was clearly recognized under high temperatures. The water soluble compoents such as total solids, nitrogen and reducing sugar during water-soaking at 2$0^{\circ}C$ for 16hrs were appreciably eluted from the soybeans stored for 8 months at high temperatures. The pH of the water extract slightly shifted to the acidic range.

• 태양에너지
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• 제19권4호
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• pp.33-43
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• 1999

The study on ice thermal storage system is to improve total system performance and increase the economical efficiency in actual all-conditioning facilities. To obtain the high charging and discharging efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therefore the process flow must be piston flow in the cylindrical type. With the relation of the aspect ratio(H/D) in the storage tank, the stratification is formed better as inlet flow rate is smaller. If the inlet and the outlet port are settled at the upside and downside of the storage tank, higher storage rate could be obtainable. In case that the flow directions inside the thermal storage tank are the upward flow in charging and the downward in discharging, thermal stratification is improved because the thermocline thickness is maitained thin and the degree of stratification increases respectively. In the charging process, in case of inlet flow rate the thermal stratification has a tendency to be improved with the lower flow rate and smaller temperature gradient in case of inlet temperature, the large temperature difference between inflowing water and storage water are influenced from the thermal conduction. The effect of the reference temperature difference is seen differently in comparison with the former study for chilled and hot water. In the discharging process, the thermal stratification is improved by the effect of the thermal stratification of the charging process.

• Preventive Nutrition and Food Science
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• 제3권3호
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• pp.234-240
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• 1998

This study attempted to determine the effect of various thawing methods and storage periods on the quality of froen cooked rice. Frozen cooked rice was thawed at four different methods, such as pressure cooking, conventional cooking, microwave heating and thawing at room temperature after 10 days, 30days and 90 days frozen storage. We conducted a physico-chemical analysis (moisture content, dehydration rates, degree of gelatinization, color value and texture) and sensory evalution on the frozen-thawed cooked rice. The study showed that there were no significant differences on the quality characteristics of frozen-thawed cooked rice during the storage period of 90 days. However, the thawing method of pressure cooking caused high moisture content, rapid dehydration rates, and a high degree of gelatinization on the cooked rice. Thus, the desirabililty for the rice diminished becaused of the excess moisture content and the change of appearance and testure in the rice due to the high temperature. There were similiar quality characteristics to the cooked rice after forzen-thawing whether by conventional cooking or by microwave heating and just after cooking. Thawing at room temperature also caused a significant decrease in quality characteristics.