• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.922-927
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• 1998

Pipe cooling has been popularly used in the mass concreting work to reduce temperature of the structure since it is known to be the easiest way to apply and has been the customary usage. But wrong application of the system results in the harmful effect on the structure by crack formation due to thermal shocks and improper cooling schemes. Thus, this study aims at the suppling of effective cooling methods through parametric study. For this, circulating method, velocity of water supply and circulating duration were selected as critical factors affecting the effectiveness of cooling system. As a results of thermal analysis, it was found that too much thermal gradient in the vicinity of the pipe creates localized radial or circumferential cracks. The duration of circulating cooling may be recommended to be as short as several days which may safely reduce the concrete temperature to below a final stable value. It was also found that pipe cooling is more effective to decrease the degree external restraints than internal one.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.48-53
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• 2014

In December 2011 and July 2012, two sets of 840MVA hydro-generator of Three Gorges on Yangtze River with Close-loop-self-circulating evaporative cooling (CLSCEC) system were put into commercial operation. In this paper, we make engineering summary of these two generators with CLSCEC system. We also make a comparison between the internal water cooling (IWC) hydro-generator and the CLSCEC hydro-generator used in Three Gorges power plant in fields of their operating characteristics, working performances, technical features, working safety and reliability. In addition, engineering structures, type tests' results and systematic emulating calculation of CLSCEC schemes are analyzed.

• Journal of Biosystems Engineering
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• 제39권1호
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• pp.34-38
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• 2014

Purpose: In this study, the performance of cooling system with the water-water heat pump system of 100kW scale made for cooling agricultural facilities, especially for horticultural facilities, was analyzed. It was intended to suggest performance criteria and performance improvement for the effective cooling system. Methods: The measuring instruments consisted of two flow meters, a power meter and thermocouples. An ultrasonic and a magnetic flow meter measured the flow rate of the water, which was equivalent to heat transfer fluid. The power meter measured electric power in kW consumed by the heat pump system. T-type thermocouples measured the temperature of each part of the heat pump system. All of measuring instruments were connected to the recorder to store all the data. Results: When the water temperature supplied into the evaporator of the heat pump system was over $20^{\circ}C$, the cooling Coefficient Of Performance(COP) of the system was higher than 3.0. As the water temperature supplied into the evaporator, gradually, lowered, the cooling COP, also, decreased, linearly. Especially, when the water temperature supplied into the evaporator was lower than $15^{\circ}C$, the cooling COP was lower below 2.5. Conclusions: In order to maintain the cooling COP higher than 3.0, we suggest that the water temperature supplied into evaporator from the thermal storage tank should be maintained above $20^{\circ}C$. Also, stratification in the thermal storage tank should be formed well and the circulating pumps and the pipe lines should be arranged in order for the relative low-temperature water to be stored in the lower part of the thermal storage tank.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.503-508
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• 2005

An advanced Research Reactor (ARR) consists of an open-tank-type reactor assembly within a light water pool and generates thermal power of 20 MW. The thermal power is including a fission heat in the core, a fuel generated heat temporary stored in the pool, a circulating pumps generated heat and a neutron reflecting heat in the reflector vessel of the reactor. In order to remove the heat load, the primary cooling system will be installed. In this study, the conceptual design of the primary cooling system has been carried out using a design methodology of HANARO within a permissible range of safety. As results, it has been established that the conceptual design of the primary cooling system including design requirements, performance requirements, design restrictions, system descriptions and system operation to maintain the system functions.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.459-468
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• 2013

During a station blackout (SBO), the initiating event is a loss of Class IV and Class III power, causing the loss of the pumps, used in systems such as the primary heat transporting system (PHTS), moderator cooling, shield cooling, steam generator feed water, and re-circulating cooling water. The reference case of the SBO case does not credit any of these active heat sinks, but only relies on the passive heat sinks, particularly the initial water inventories of the PHTS, moderator, steam generator secondary side, end shields, and reactor vault. The reference analysis is followed by a series of sensitivity cases assuming certain system availabilities, in order to assess their mitigating effects. This paper also establishes the strategies to mitigate SBO accidents. Current studies and strategies use the computer code of the Integrated Severe Accident Analysis Code (ISAAC) for Wolsong plants. The analysis results demonstrate that appropriate strategies to mitigate SBO accidents are established and, in addition, the symptoms of the SBO processes are understood.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.580-589
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• 2019

인도네시아는 전력 공급이 매우 부족한 현실에 처해 있으며, 이에 대한 해결책으로 화력발전소 건설 계획이 증가하고 있다. 화력발전소는 발전에 수반되는 엔진과 장비의 과열을 식히기 위해 냉각수 계통을 필요로 하며, 냉각수 계통 중 순환수 취수펌프장(circulating water pump chamber)은 일반적으로 ANSI (1998) 기준에 따라 설계된다. 본 연구에서는 인도네시아 K-석탄화력발전소의 순환수취수펌프장이 현장 여건상 ANSI (1998)의 확산각 설계기준 $20^{\circ}$를 만족시킬 수 없어, 수리적으로 안정된 흐름 및 구조물이 되도록 3차원 수치모형실험을 수행하였다. 수치모형으로 Flow-3D 모형을 이용하였다. Flow-3D 모형의 적용성을 검토하기 위해 Rodi (1997)의 사각형 구조물 주변에 형성되는 흐름 연구 결과와 금회 수치해석 결과를 비교하였다. 수치해석에서 도출된 종방향 유속 분포는 잘 일치함을 보여주고 있다. 순환수취수펌프장 내 설계유속을 만족시키기 위해 유속 저감에 유리한 사각형 형태의 배플을 적용하였다. 순환수취수펌프장으로 유입되는 유속이 1.5 m/s ~ 2.5 m/s로 분포되는 경우, 배플에서 분리흐름의 각도는 약 $15^{\circ}{\sim}20^{\circ}$로 발생하였다. 이를 고려하여 분리흐름 각도 이하로 하류에 배플을 배치함으로 Inlet bay 설계유속 0.5 m/s 이하를 만족시켰다.

• Corrosion Science and Technology
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• 제9권5호
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• pp.187-195
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• 2010

Hyper duplex stainless steels have been developed in Korea for the purpose of application to the seawater system of Korean nuclear power plants. This system supplies seawater to cooling water heat exchanger tubes, related pipes and chlorine injection system. In normal operation, seawater is supplied to heat exchanger through the exit of circulating water pump headers, and the heat exchanged sea water is extracted to the discharge pipes in circulating water system connected to the circulating water discharge lines. The high flow velocity of some part of seawater system in nuclear power plants accelerates damages of components. Therefore, high strength and high corrosion resistant steels need to be applied for this environment. Hyper duplex stainless steel (27Cr-7.0Ni-2.5Mo-3.2W-0.35N) has been newly developed in Korea and is being improved for applying to nuclear power plants. In this study, the physical & mechanical properties and corrosion resistance of newly developed materials are quantitatively evaluated in comparative to commercial stainless steels in other countries. The properties of weld & HAZ (heat affected zone) are analyzed and the best compositions are suggested. The optimum conditions in welding process are derived for ensuring the volume fraction of ferrite(${\alpha}$) and austenite(${\gamma}$) in HAZ and controlling weld cracks. For applying these materials to the seawater heat exchanger, CCT and CPT in weldments are measured. As a result of all experiments, it was found that the newly developed hyper duplex stainless steel WREMBA has higher corrosion resistance and mechanical properties than those of super austenitic stainless steels including welded area. It is expected to be a promising material for seawater systems of Korean nuclear power plants.

• 한국항해항만학회지
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• 제34권1호
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• pp.71-75
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• 2010

아이스슬러리의 생성을 위하여 냉각평판에 작동수를 분사하는 실험을 수행하여 그에 대한 영향에 대하여 영향을 평가하였다. 실험에 사용된 에틸렌글리콜 수용액은 10~20wt%의 수용액을 사용하였다. 실험장치는 슬러리아이스 저장탱크, 브라인 탱크, 브라인 순환장치, 유량계 및 온도기록계로 구성되어 있다. 실험조건은 평균유속 1.0~2.0m/s, 냉각온도 $-17{\sim}-10^{\circ}C$의 조건 하에 실험을 수행하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1324-1329
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• 2001

The depression of the external situation like the departure of WTO system and the plan of EEZ proclaim is forcing fishery into improving their fishing condition. By this international and domestic circumstance, development of the sea water cooling apparatus for fish hold storage is demanded sincerely. This study represents the thermal characteristics of the fish hold storage during transportation. The numerical analysis in this study is the finite volume method with the SIMPLE computational algorithm to study the seawater flow behavior in the fish hold storage. The computation were carried out with the variations of the circulating flow velocity and depth of fish hold storage. As the result of the three dimensional simulations, the mean temperature doesn't almost change by the circulating flow rate. find the mean temperature is suddenly changed by the ratio of depth of fish hold storage.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2003년도 학술대회지
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• pp.202-213
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• 2003

타워팰리스 III 현장은 현존하는 국내 건축물로는 가장 높은 초고층 주상복합건물이다. 초고층 현장에는 일반현장과는 다른 시공기술 및 엔지니어링 기술의 적용이 요구되는 바, 타워팰리스 III 현장은 지금까지 축적된 기술을 바탕으로 보다 발전된 시공기술과 엔지니어링 기술, 그리고 공정관리기법을 통하여 마감공사 포함 충 당 13.4일이라는 공사 속도를 달성하였다. 이와 같은 공사를 성공적으로 수행하기 위하여 적용된 첨단 시공기술로 1) 골조공사 및 외벽공사의 3-Day Cycle을 달성하기 위한 여러 가지 공법, 2) 초고층 주거건물의 마감공사 공정관리를 위한 Tact 공정관리 시스템, 3) 현장관리 시스템으로 물류관리 및 정보공유 시스템 등이 적용되었다. 또한 엔지니어링 요소기술로 1) 고유동 무다짐 콘크리트와 국내 최초의 압축강도 $800kgf/cm^{2}$의 초고강도 콘크리트 등의 New Material, 2) 냉각수 순환형 파이프쿨링 시스템 등의 New Method, 3) Smart Fan Control 주방환기 시스템을 포함한 Mechanical System 4) False Car System을 포함한 Electrical System 등이 있다.