• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.152-157
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• 2008

Enclosure is widely used for the sound insulation in a ship. But it is very difficult to estimate the sound insertion loss for the enclosure because the sound field between the enclosure and the machine is so complex. Therefore, it is usually estimated experimentally. In this research, sound insertion loss of the enclosure is estimated by theory assuming that the sound field in the enclosure is reverberation field. And the results from the theory are compared to those from the experiment.

• 설비공학논문집
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• 제12권1호
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• pp.33-39
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• 2000

There are many under going researchs for the natural convection and fluid flow in rectangular enclosure. In this paper, the optimal model that is the most frequently used for the analysis of a turbulent natural convection in rectangular enclosure is suggested by comparing with the result of Cheesewright's experiment. As We can see the distribution of the velocity, temperature, and turbulent kinitic energy, ST model tends to exaggerate the result of the experiment. The LS model generates better experimental result than the ST and DA's. Therefore, it is resonable to adopt the LS model that contains explicit physical meanings of each term in eouation of turbulent kinitic energy.

• The Korean Journal of Ecology
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• 제23권4호
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• pp.299-307
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• 2000

To understand the mechanism of phytoplankton succession in the Nakdong River, the resource availability (silica) and grazing effect on the phytoplankton community were investigated in an enclosure experiment at Mulgum in March 1995. In all enclosures, Stephanodiscus hantzchii was dominant during the first week. Two weeks later, the diatom community in the A (river water only) and B (filtered river water) enclosures was shifted to colonial green algae (Actinastrum sp., Pediastrum spp. and Scenedesmus spp.) and nanoplankton (2~3 ${\mu}$m of diameter) due to the silica depletion. In the C (silica addition in river water, 3 mg 1$^{-1}$ week$^{-1}$) and D (silica addition in filtered water) enclosures, Fragilaria crotonensis and Synedra acus increased as the silica addition was continued. The percentage of small phytoplankton (size, 10~13 ${\mu}$m) in the filtered enclosures (B and D) was much higher than that of A and C enclosures. A laboratory bottle experiment conducted in the fall of 1994 also showed similar results. Therefore, it is concluded that silica and zooplankton are important regulators in phytoplankton succession during the diatom blooming season in the Nakdong River.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.602-607
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• 2003

We show three-dimensional distribution of voltages resulted from the leakage current originated from outdoor electrical facilities in a submerged area. In case these facilities are grounded by the neutral line multiple grounding method, the existence of ungrounded electrical facilities can cause a disastrous effect on near-by passengers. In order to investigate this situation, we installed a real-scale test field for the experiment type I (for the leakage current path between a enclosure grounded electrical facility and another enclosure grounded one), and that for the experiment type II (for the leakage current path between a enclosure grounded electrical facility and another ungrounded one). For both cases, we carried out three-dimensional monitoring of the voltage distribution while varying additional conditions such as the exposure of the underground cables and the finishing of cable connection part. The result shows that a disastrous effect on human safety can arise from the leakage current without a pertinent measure for the construction and maintenance of outdoor electrical facilities.

• 한국화재소방학회논문지
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• 제29권1호
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• pp.60-66
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• 2015

본 연구에서는 가스계 소화설비시스템이 설치된 방호구역에 소화농도유지시간 성능실험인 밀폐도 시험(Enclosure Integrity Test)를 진행하여, 성공에 미치는 사전조치요인에 대하여 실험하였다. 국내외에 발전소 방호구역에 사전 조치를 취한 방호구역과 사전 조치를 취하지 않은 방호구역으로 나누어 Enclosure Integrity Test를 진행하였다. 따라서, 사전조치 여부에 따라 시험의 성공률을 알아보고, 각각의 가스계 소화시스템 및 실의 종류에 따른 Enclosure Integrity Test의 실패 요인, 설계 농도 유지시간 및 체적대비 누설면적의 크기를 확인하였다. 그리고 사전조치를 수행하여 Enclosure Integrity Test의 성공률이 증가되는 것을 알 수 있으며, 실패에 의해 반복되는 실험의 수를 줄임으로 인하여 발생되는 비용을 절약할 수 있었다.

• 대한설비공학회지:설비저널
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• 제16권2호
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• pp.204-215
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• 1987

Laminar natural convective heat transfer within a two-dimensional rectangular enclosure with horizontal conducting walls and partitions was investigated by numerical analysis and experiment. The enclosure consists of two isothermal vertical walls and two adiabatic horizontal walls. This combined heat transfer problem of conduction and natural convection was solved using finite difference method with SIMPLE algorithm, and temperature distribu-tions in the air filled enclosure was obtained using Mach-Zehnder interferometer. Good agree-ment was obtained between the predicted and measured results. The effect of geometric parameters and thermal properties on heat transfer was studied far Grashof numbers in range, $1\times10^4\;{\leqslant}\;G^r\;{\leqslant}\;6.4\times10^5.$ It was found that both velocity and temperature fields were in-fluenced significantly by thermal conductivity of the conducting walls and the partitions, and by geometry of partitions.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.294-301
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• 2004

The natural convective heat transfer in a rectangular enclosure with a heating source has been studied by experiment and numerical analysis. The governing equations were solved by a finite volume method, a SIMPLE algorithm was adopted to solve a pressure term. The parameters for the numerical study are positions and surface temperatures of a heating source i.e., Y /H =0.25, 0.5, 0.75 and 11$^{\circ}C$ $\leq$ΔT$\leq$59$^{\circ}C$. The results of isotherms and velocity vectors have been represented, and the numerical results showed a good agreement with experimental values. Based on the numerical results, the mean Nusselt number of the rectangular enclosure wall could be expressed as a function of Grashof number.

• 생태와환경
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• 제33권4호통권92호
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• pp.358-365
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• 2000

백련어의 도입 및 제거가 부영양호의 수중생물군집과 환경요인에 미치는 영향을 조사하였다. 생물조작을 위해 호수연안에 6개의 enclosure를 설치하고, 5월 22일부터 7월 23일까지(전기), 7월 23일부터 9월 18일까지(후기) 두 가지 밀도(고, 저)의 어류를 투입 및 제거하였다. RIA(${\alpha}$=0.05)의 결과는 어류도입 및 제거가 대부분의 생물군집 및 환경요인에 유의한 영향을 미치는 것으로 나타났다. 각 enclosure의 환경요인에 대해 어류투입은 투명도, 용존산소, 수소이온농도, 큰분획엽록소(>40 ${\mu}$m) 등의 감소와 질소화합물, 소형분획엽록소(<2 ${\mu}$m)의 증가를 유도하였으며, 어류제거는 정반대 현상을 보였다. 한편, 수중생물군집에 있어서, 어류투입은 picocyanobacteria이나 섬모충(<20 ${\mu}$m) 같은 소형 플랑크톤의 증가가 뚜렷하였고, 어류제거에 의해 다시 유의하게 회복하였다. 그러나 크고, 군체를 형성하거나 긴 사상체 남조나 규조등은 두 가지 어류조작에 유의한 변화를 보이지 않았으며, 어류제거시만 Diaphanosoma, Cyclopoida, naupli 등 동물플랑크톤의 유의한 증가를 나타냈다. 본 연구는 실험기간 동안 강한 바람과 호수바닥으로부터 지속적인 인의 공급 등으로 인하여 결과해석에 부정적으로 작용하였으나, 전체적으로 어류도입 및 제거가 enclosure내 플랑크톤군집과 환경요인에 대해 서로 상반되는 효과를 유도하는 것이 확인되었다.

• 생태와환경
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• 제35권2호통권98호
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• pp.123-132
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• 2002

인공부영양화 실험실에서 조류를 대량 증식 시켜 초기세포수의 농도가 $10^4\;cells/ml$가 되게 한 후 잣잎, 솔잎, 은행잎은 각각 0.5 g/l를 투여하였고 애기마름은 0.3 g/l를 투여하여 조류제어 효과를 실험하였다. 그리고 북한강 인근의 바지선에 현장 조류제어 실험조를 설치하여 남조류(Microcystis)가 최대로 증식할 때 솔잎은 0.3 g/l를 투여하여 조류제어 실험을 수행하였다. 인공실험지에서는 잣잎과 솔잎은 Chl-3와 조류세포수 모두 평균 65%의 억제 효율을 보여 비교적 양호한 효과를 나타내었다. 그러나 은행잎은 Chl-a는 33%, 조류세포수는 55%로 잣잎과 솔잎에 비하여 조류제어 효과가 다소 감소하였다. 애기마름도 0.1 g/l와 0.3 g/l로 투여량과는 거의 상관없이 Chl-a늘 34%, 조류세포수는 $55{\sim}67%$의 조류증식 억제 효과를 보였다. 5현장 실험조에서는 초기 Chl-a농도는 $70{\sim}90\;{\mu}g/l$로 비교적 높은 농포를 보였으며 우점조류는 남조류인 Microcystis이었다. 솔잎은 Chl-a로보았을 때는 74%, 조류세포수는 83%의 조류제어효과를 보였다. 은행잎은 Chl-a로 보았을 때는 40%, 조류세포수는 65%로 솔잎 투여에 비해서는 조류 증식억제 효과가 감소하였다. 식물체를 이용한 조류제어실칩 결과 솔잎이 현장에서 조류제어 효과가 가장 좋은 것으로 분석되었고 투여량은 0.3 g/l가 이상적이며 다음이 잣잎 0.5 g/l가 비교적 양호한 효과를 보였다. 솔잎 투여량은 0.3 g/l에서 $70{\sim}80%$의 조류제어 효과를 나타내었고 독소량도 80%이상 제거되었다. 한편 은행잎과 애기마름은 조류제어 효과는 있는 것으로 추정되나 투여량은 추가적으로 실험을 더 수행해야 결정할 수 있을 것으로 본다. 식물체내 유기화합물 분석결과 조류제어에 효과가 있는 페놀 성분이 검출되었고 식물체 생태독성시험 결과 식물체 투여량은 $1{\sim}5\;g/l$가 적정한 것으로 분석되었다.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.42-48
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• 2016

This study presents an experiment investigation on natural convection heat transfer of air-cooling Proton exchange membrane fuel cells (PEMFCs) in a enclosure system for unmanned aerial vehicles (UAVs). Considered are replacing fuel cell stack with Aluminum block for heat generating inside a enclosure chamber. The volume ratio of fuel cell stack and chamber for simulation to the actual size of aerial vehicle is 1 to 15. The parameters considered for experimental study are the environmental temperature range from $25^{\circ}C$ to $-60^{\circ}C$ and the block heat input of 10 W, 20 W and 30 W. Effect of the thermal conductivity of the block and power level on heat transfer in the chamber are investigated. Experimental results illustrate the temperature rise at various locations inside the chamber as dependent upon heat input of fuel cell stack and environmental temperature. From the results, dimensionless correlation in natural convection was proposed with Nusselt number and Rayleigh number for designing air-cooling PEMFC powered high altitude long endurance (HALE) UAV.