• 설비공학논문집
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• 제29권10호
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• pp.538-550
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• 2017

In a PWR (Pressurized Water Reactor), the appropriate heat removal from the surface of fuel rod bundle is important for ensuring thermal margins and safety. Although many CFD (Computational Fluid Dynamics) software have been used to predict complex flows inside fuel assemblies with mixing vanes, there is no domestic regulatory guideline for the comprehensive evaluation of CFD software. Therefore, from the nuclear regulatory perspective, it is necessary to perform the systematic assessment and prepare the domestic regulatory guideline for checking whether valid CFD software is used for nuclear safety problems. In this study, to provide systematic evaluation and guidance on the applicability of CFD software to the domestic nuclear safety area, the results of the sensitivity analysis for the effect of the discretization scheme accuracy for the convection terms and turbulence models, which are main factors that contribute to the uncertainty in the calculation of the nuclear safety problems, on the prediction performance for the turbulent flow distribution inside the fuel assembly with split-type mixing vanes were explained.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.311-312
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• 2004

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 추계학술발표회요약집
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• pp.141-141
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• 1998

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.141.2-141
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• 2002

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.440-441
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• 2005

• 환경생물
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• 제35권1호
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• pp.83-94
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• 2017

본 연구는 2015년 12월부터 2016년 2월까지 고온배수 배출시설에서 온배수가 유입되는 경기도 포천시 영북면에 위치한 부소천 일대에서 조사를 실시하였다. 조사지점은 온배수가 유입되는 혼합역과 혼합역을 기준으로 상 하류 지점을 선정하여 수질 분석 및 저서성 대형무척추동물의 종조성, EPT-group 개체 비율, 군집 분석, 기능군 분석, 생물학적 하천 건강성을 평가하였다. 조사기간 동안 출현한 저서성 대형무척추동물은 총 3문 4강 11목 30과 50종 4,015개체이며, 출현종 비율은 하루살이목이 6과 16종 (32.00)%, 개체수 비율은 파리목이 1,848개체 (46.03%)로 가장 높게 나타났다. 하루살이-강도래-날도래목 (EPT-group)이 조사기간 동안 총 17과 32종 1,876개체 (46.72%)가 출현하였으며, 1차에서 3차 조사기간 동안 혼합역에서 가장 낮은 출현율을 나타냈다. 군집 분석 결과 혼합역에서 비교적 넓은 수온대를 가지는 실지렁이 (Limnodrilus gotoi)와 깔따구 sp2.(Chironomidae sp.2)가 우점하는 것으로 분석되었으며, 네점하루살이 (Ecdyonurus levis), 민하루살이 (Cincticostella levanidovae), 민강도래 KUa (Nemoura KUa) 등이 우점종으로 분석된 상 하류 지점과 차이를 나타냈다. 섭식기능군 분석 결과 상류와 혼합역에서 Gathering-Collectors, 하류에서는 Filtering-Collectors의 비율이 가장 높은 것으로 분석되었고, 상류에서 하류로 갈수록 Shredders의 비율이 감소하였다. 서식기능군은 Clingers와 Burrowers가 대부분을 차지하였으며, 상류에서 하류로 갈수록 Clingers의 비율이 높아지는 것으로 분석되었다. 하천 건강성 평가 결과 평균 2.73 (${\pm}0.41$)으로 혼합역에서 가장 불량한 상태를 나타내는 것으로 분석되었다. 수온과 냉수성종의 상관성 분석 결과 수온이 증가할수록 냉수성 선호종 및 EPT-group은 감소하는 것으로 분석되었다. 혼합역에 유입되는 고온의 방류수는 하천생태계에 교란을 일으키는 요인으로써 저서성 대형무척추동물 군집과 냉수성 선호종 및 민감종의 분포에 부정적인 영향을 미치고 있는 것으로 판단된다.

• 한국전산유체공학회지
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• 제20권3호
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• pp.8-14
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• 2015

More and more, spaces are decreasing which satisfy multiple requirements for wind power plants. However, areas which have excellent wind resources and are free to civil complaints occupy a large space, although they are exposed to the cryogenic environment. This study conducted a thermal-fluid analysis of a cryogenic chamber for testing large wind turbine parts exposed to the cryogenic environment. The position of supply air is placed to the upper area to compare each cooling performance for each location of various outlets in mixing ventilated conditions. The study carried out CFD analysis for the chamber both with and without a test object. For the cases without the test object, the air temperature of the upper supply and down extract type chamber was cooled faster by 5-100% than the others. However, for the cases with the test object, the object temperature of upper supply and center extract on the opposite side type chamber was cooled faster by 33-132% than the others. The cooling performance by the air inside the chamber and the test object did not show the same pattern, which implicates the need to consider the cooling performance by not only the air but also the test object in the large cryogenic chamber design for testing large parts.

• 설비공학논문집
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• 제29권5호
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• pp.259-268
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• 2017

This paper proposes a hydrogen-based social economy derived from fuel cells capable of replacing fossil fuels and resolving global warming, It thus provides an entry for developing economically feasible social configurations to make use of bio-hydrogen production systems. Bio-hydrogen production works from the principle that microorganisms decompose water in the process of converting CO to $CO_2$, thereby producing hydrogen. This study parts from an analysis of an existing 157-ton class NA1 bio-hydrogen reactor that identifies the state of feedstock and reactor conditions. Based on this analysis, we designed a 1-ton class bio-hydrogen reactor process simulator. We carried out thermal analyses of biological heat reactions, sensible heat, and heat radiation in order to calculate the thermal load of each system element. The reactor temperature changes were determined by modeling the feed mixing tank capacity, heat exchange, and heat storage tank. An analysis was carried out to confirm the condition of the feed mixing tank, heat exchanger, heat storage tank capacity as well as the operating conditions of the system so as to maintain the target reactor temperature.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1298-1306
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• 2005

In this paper, Part II, we realized the Serpentine Laminating Micromirer (SLM) which was proposed in the accompanying paper, Part I, by means of the injection molding process in mass production. In the SLM, the higher level of chaotic mixing can be achieved by combining two general chaotic mixing mechanisms of splitting/recombination and chaotic advection by the successive arrangement of 'F'-shape mixing units in two layers. Mold inserts for the injection molding process of the SLM were fabricated by SU-8 photolithography and nickel electroplating. The SLM was realized by injection molding of COC (cyclic olefin copolymer) with the fabricated mold inserts and thermal bonding of two injection molded COC substrates. To compare the mixing performance, a T-type micromixer was also fabricated. Mixing performances of micromixers were experimentally characterized in terms of an average mixing color intensity of a pH indicator, phenolphthalein. Experimental results show that the SLM has much better mixing performance than the I-type micromixer and chaotic mixing was successfully achieved from the SLM over the wide range of Reynolds number (Re). The chaotic micromixer, SLM proposed in this study, could be easily integrated in Micro-Total-Analysis- System , Lab-on-a-Chip and so on.