• Journal of Biosystems Engineering
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• 제25권5호
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• pp.379-384
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• 2000

In order to use the natural thermal energy as much as possible for greenhouse heating, the air-air heat pump system involved PCM(phase change material) latent heat storage system was composed, and three types of greenhouse heating system(greenhouse system, greenhouse-PCM latent heat storage system, greenhouse-PCM latent heat storage-heat pump system) were recomposed from the greenhouse heating units to analyze the heating characteristics. The results could be concluded as follows; 1) In the greenhouse heated by the heat pump under the solar radiation of 406.39W/$m^2$, the maximum PCM temperature in the latent heat storage system was 24$^{\circ}C$ and the accumulated thermal energy stored in PCM mass of 816kg during the daytime was 100,320kJ. In the greenhouse without heat pump under the maximum solar radiation of 452.83W/$m^2$, the maximum PCM temperature in the latent heat storage system was 22$^{\circ}C$ and the accumulated thermal energy stored during the daytime was 52.250kJ. 2) In the greenhouse-PCM system without heat pump the heat stored in soil layers from the surface to 30cm of the soil depth was 450㎉/$m^2$. 3) In all of the greenhouse heating systems, the difference between the air temperature in greenhouse and the ambient temperature was about 20~23$^{\circ}C$ in the daytime. In the greenhouse without heat pump and PCM latent heat storage system the difference between the ambient temperature and the air temperature in the greenhouse was about 6~7$^{\circ}C$ in the nighttime, in the greenhouse with only PCM latent heat storage system the temperature difference about 7~13$^{\circ}C$ in the nighttime and in the greenhouse with the heat pump and PCM latent heat storage system about 9~14$^{\circ}C$ in the nighttime.

• 한국식품위생안전성학회:학술대회논문집
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• 한국식품위생안전성학회 2001년도 The Asia-Pacific Conference on Reproductive Biology and Environmental Sciences
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• pp.127-130
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• 2001

• 신재생에너지
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• 제3권2호
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• pp.60-67
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• 2007

This paper describes the design and integration of the wind-fuel cell hybrid system. The hybrid system components included a wind turbine, an electrolyzer (for generation of H2), a PEMFC (Proton Exchange Membrane Fuel Cell), hydrogen storage tank and BOP (Balance of Plant) system. The energy input is entirely provided by a wind turbine. A DC-DC converter controls the power input to the electrolyzer, which produces hydrogen and oxygen form water. The hydrogen used the fuel for the PEMFC. Hydrogen may be produced and stored in high pressure tank by hydrogen gas booster system. Wind conditions are changing with time of day, season and year. So, wind power is a variable energy source. The main purpose with these WT-FC hybrid system is to store hydrogen by electrolysis of water when wind conditions are good and release the stored hydrog en to supply the fuelcell when wind is low.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.685-688
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• 2006

본 논문에서는 초전도에너지저장 시스템에 적합한 간략한 회로 구성과 높은 신뢰성을 가지는 단상 무정전 전원공급장치를 제안한다. 제안된 시스템은 공통암 방식을 적용하여 스위칭 소자수를 저감한다. Normal, Stored-energy, Bypass의 세 가지 동작 모드에 대하여 상세히 설명한다. 사용되는 스위칭 소자수를 저감시키거나 수동소자로 대체시킬 경우 제어가 복잡해지고 자유도를 감소키는 문제점이 있지만 고성능의 디지털 제어기를 통해 추가적인 부담 없이 해결할 수 있다. 제안된 시스템의 타당성 검증을 위해 시뮬레이션 결과를 제시한다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.363-365
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• 2005

It describes a design analysis and test results of an energy transfer system which consists of two 0.5 MJ superconducting coil and three Inverter-Converter Bridges(hereinafter called ICB). A point of design is to satisfy the required stored energy capacity rather than magnetic field density with minimum energy transfer time using the calculation results of state-space averaging methods instead of Fourier series. It is proven that the considered methods are effectively through system experiments.

• 전자통신동향분석
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• 제34권2호
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• pp.101-109
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• 2019

Electrical energy storage (EES) systems store generated electricity in energy storage devices such as batteries and discharge the stored energy when necessary. Individual subsystems of the EES system are being standardized independently; however, a holistic understanding of the whole system is necessary because the EES system is large and complex. IEC TC 120 has developed international standards of EES systems. In this paper, EES systems standards in IEC TC 120, including the planning and installation of EES systems, are presented. Further, ongoing standardization for the application of EES systems to backup power and emergency support is described.

• 에너지공학
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• 제16권4호
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• pp.164-169
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• 2007

우리나라에서 여름철 피크전력부하의 감소는 매우 중요하다. 정부는 피크전력부하를 저감하기 위하여 많은 지원 정책과 법률을 제정하여 시행하고 있다. 그리고 빙축열시스템은 이런 대안 중의 하나로서 알려지고 있다. 이 논문의 목적은 축열운전, 병렬운전과 축열조 단독운전이 수행된 밀폐식 빙축열시스템의 축열조 성능과 전체 효율을 평가하는 것이다. 설계조건에서 운전된 빙축열시스템의 자료를 이용하여 축열조의 축열밀도와 방냉효율 그리고 시스템의 총괄에너지 이용효율을 계산하면 $18.4\;USRT-h/m^3$, 96.2% 그리고 2028.7 kcal/kWh이다. 빙축열시스템의 축열조에 공급되는 에너지를 설계조건보다 많게 공급하면 과냉각효과에 의해 설계조건보다 시스템 효율이 낮게 평가되어진다.

• Food Quality and Culture
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• 제3권2호
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• pp.53-58
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• 2009

This study was conducted to investigate the quality characteristics of frozen stored mungbean starch gels added with sucrose fatty acid ester (SE). The study showed a delay of gelatinization of mungbean starch by SE addition through the measurements conducted by using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC). In the color of SE added frozen stored gels, lightness (L) and yellowness (b) values were increased compared to those of values measured from freshly prepared gel, whereas redness (a) value was decreased. The addition of 1% SE on mungbean starch gel prevented the color change during frozen storage. Rupture stress and rupture energy of frozen stored gel was higher than those of freshly prepared gel, whereas rupture strain of frozen stored gel was lower than that of freshly prepared gel. The addition of 1% SE on mungbean starch gel prevented the change of rupture characteristics during frozen storage. Texture profile analysis(TPA) characteristics revealed a significant change of the gel texture during frozen storage by showing an increase of hardness of the frozen stored gels compared to the freshly prepared gels with newly discovered fracturability, which resulted to show a large difference of gel texture by showing the disappearance of adhesiveness and large reduction of cohesivenes. The addition of 1% SE on mungbean starch gel prevented the change of TPA characteristics during frozen storage. Scanning electron micrographs showed that network structure of frozen stored gel was more rough than that of freshly prepared gel, and the addition of 1% SE on mungbean starch gel could suppress the breakdown of network structure. Thus the addition of 1.0% SE on mungbean starch gel was appropriate method for remaining gel characteristics during frozen storage.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1368-1375
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• 2016

A radiological safety assessment study was performed for the transportation of low level radioactive wastes which are temporarily stored in Korea Atomic Energy Research Institute (KAERI), Daejeon, Korea. We considered two kinds of wastes: (1) operation wastes generated from the routine operation of facilities; and (2) decommissioning wastes generated from the decommissioning of a research reactor in KAERI. The important part of the radiological safety assessment is related to the exposure dose assessment for the incidentfree (normal) transportation of wastes, i.e., the radiation exposure of transport personnel, radiation workers for loading and unloading of radioactive waste drums, and the general public. The effective doses were estimated based on the detailed information on the transportation plan and on the radiological characteristics of waste packages. We also estimated radiological risks and the effective doses for the general public resulting from accidents such as an impact and a fire caused by the impact during the transportation. According to the results, the effective doses for transport personnel, radiation workers, and the general public are far below the regulatory limits. Therefore, we can secure safety from the viewpoint of radiological safety for all situations during the transportation of radioactive wastes which have been stored temporarily in KAERI.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.280-285
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• 2001

This paper presents a modelling of thermal discharge performance for a static ice-on-coil ice-storage tank. Through the present study, discharging characteristics were examined with the existing results of theoretical and numerical heat transfer analyses. Also, an experiment was conducted to obtain a real set of discharge performance. The thermal effectiveness, the ratio of the actual heat transfer rate to the maximum possible heat transfer rate, decreased when the stored energy decreased during discharging period. And the effectiveness increased as the coolant flow rate through the storage increased, of which increasing rate decreased abruptly near the maximum and the minimum stored energy. An empirical correlation was obtained from the experimental and the numerical analysis data.