• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.117-122
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• 2000

In these days, the pollution of marine environment near island at Korean coastal zone caused by the trash, human waste and livestocks excreta become series problem. One of the most economic and efficient way to prevent this pollution problem is to set up island circulating incineration system. In this paper, the results of feasibility study on the application of turtle boat hull form to the incinearting vessel has been summarized especially for the resistance and course keeping point of view.

• International Journal of Fluid Machinery and Systems
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• 제7권2호
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• pp.80-85
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• 2014

In this study, we visualized the internal flow of a regenerative turbomachinery using the direct injection tracer method. For visualization, the working fluid was water and the tracer was oil colors (marbling colors). Droplets were injected at the inlet of the machinery and the streak were recorded using a high-speed camera with high-power light sources. While circulating inside the groove, the droplets were translated by the rotational motion of the impeller. When the droplets flow out of the impeller groove, relative to the impeller, they moved more slowly. And the droplets repeatedly reentered into the groove and circulated again. Then the droplets either flowed to the outlet or to the stripper. As a result, this experiment has confirmed the internal circulating flow of a regenerative turbomachinery.

• 한국해양공학회지
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• 제11권3호
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• pp.95-99
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• 1997

In these days, the pollution of marine environment near island at Korean coastal zone caused by the trash human waste and livestocks excreata become intensified. One of the most economic and efficient way to prevent this pollution problem is to set up island circulating incineration system. In this paper, the result of feasibility study on the application of turtle boat hull form to the incinerating vessel has been summarized especially for the resistance and course keeping point of view.

• 한국해양공학회지
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• 제25권4호
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• pp.23-27
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• 2011

This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

• KIEAE Journal
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• 제15권5호
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• pp.83-88
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• 2015

Purpose: Photovoltaic system is a technique for producing electrical power by utilizing solar energy, which can be used over 20 years with simple maintenance. However, in the case of photovoltaic systems, the energy conversion efficiency decreases as the surface temperature of module increases, compared with other renewable energy technologies. In this regard, PVT module can increase the energy utilization of a composite module as producing heat and electricity simultaneously by using solar energy. Currently, many researches have been promoting in order to develop a high efficiency PVT module in Korea. However, there are a few studies about the performance of the modules corresponding the shape of types and various heat exchangers of the PVT module. In this study, the electrical performance was measured by the change of the ambient temperature and the circulating water temperature using the fabricated PVT module. Method: Experiments were performed using a solar simulator. And this experiment was assumed that the weather condition was in each season, as winter, spring, autumn and summer. It was identified that the I-V curve associated with the change of the experimental conditions and confirmed the change in the electrical characteristics. Result: As a result, it was figured out that the surface temperature and the electrical performance changes in case conditions. The electrical performance was calculated in different temperature condition and the power production was confirmed by the change of module temperature.

• 한국지열·수열에너지학회논문집
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• 제17권2호
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• pp.30-41
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• 2021

This paper presents the heating performance analysis results of a heat pump system using a dual heat source. In this paper, a dual heat source refers to the ground-coupled heat exchanger using both a surface water heat exchanger (SWHE) and a vertical ground heat exchanger (VGHE). In order to evaluate the system performance, we installed a monitoring system to measure the temperature and power consumption of a heat pump and then collected operation data with 4 different load burdened ratios of the dual heat source heat exchanger. During the whole measurement period, the average heating capacity of a water-to-water heat pump unit was 37.3 kW. In addition, the compressor of the heat pump consumed 9.4 kW of power, while the circulating pump of the dual heat source heat exchanger used 6.7 kW of power. Therefore the average heating coefficient of performance (COP) for the heat pump unit was 4.0, while the entire system including the circulating pump was 2.7. Finally, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further researches are needed to optimize the design data for various load ratios of the dual heat source heat exchanger.

• 대한조선학회논문집
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• 제34권2호
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• pp.1-10
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• 1997

예인수조에서 저항추진 성능을 추정하기 위한 선형시험을 수행한 때는 계측정도에 나쁜 영향을 주는 불안정현상에 유의하여야 한다. 불안정현상을 일으키는 큰 원인인 수조수 수심에 따른 수온의 불균일, 연중 수온의 변화, 난류촉진장치, 저항시험 사의 이복현상에 대해 검토하였다. 그리고 수조수 순환, 수조동 난방, 탈기장지 및 난류촉진장치의 개선 등을 그 해결 방안으로 제시하였다.

• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.285-291
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• 2010

To provide required flow rates of cooling or circulating water properly, approach flow conditions of vertical pump systems should be in compliance with state of the art acceptance criteria. The direct inflow should be vortex free, with low pre-rotation and symmetric velocity distribution. Physical model investigations are common practice and the best tool of prediction to evaluate, to optimize and to document flow conditions inside intake structures for vertical pumping systems. Optimization steps should be accomplished with respect to installation costs and complexity on site. The report shows evaluation of various approach flow conditions inside a compact waste water pumping station. The focus is on the occurrence of free surface vortices and the evaluation of air entrainment for various water level and flow rates. The presentation of the results includes the description of the investigated intake structure, occurring flow problems and final recommendations.

• 한국해양공학회지
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• 제21권6호
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• pp.1-6
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• 2007

A study on the new active circulation type oil-water separation system including buoyancy type guidance system was carried out in this paper. Newly developed oil-water separation system is composed of several oil separation steps. In the beginning of these steps, buoy type separation system would be used. Buoy type oil guiding system was developed based on the difference of density of water and oil.

• 유기물자원화
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• 제20권4호
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• pp.106-117
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• 2012

건조과정에서 시료의 순환과 낙하이동에 따른 건조효과를 평가하기 위하여 음식물류폐기물 8,000kg을 간접건조방식의 건조기에 투입하고 회전스크류 가동시와 미가동시에 대하여 수분함량, 건조율, 평균입자크기 및 입도분포, 증발수분량 및 건조효율을 비교하였다. 음식물류폐기물의 초기 수분함량은 77.1%로서, 회전스크류 가동시에는 가동 후 5시간 만에 수분함량이 14.4%로 낮아진 반면에 미가동시에는 16시간을 가동시켜도 수분함량 35.6%에 머물고 있어 시료의 순환과 낙하이동이 건조효과 상승에 영향을 미치고 있음을 알 수 있다. 건조시작 후 점성구간 도달 이전에는 입자크기가 증가하면서 수분증발률은 최대치를 보인다. 점성구간에서는 입자크기가 최대치를 나타내나 수분증발률은 급감하기 시작하며, 점성구간 이후에는 입자크기와 수분증발률이 동시에 감소하는 것으로 나타났다. 이는 자유수 증발량과 각 구간에서의 점성차이에 기인한 것으로 여겨진다. 평균 입자크기는 가동 후 지속적으로 증가하여 점성구간인 수분함량 70%-60% 범위에서 최대치를 보인 후 감소하는 경향을 나타내었으나 평균 입자크기의 변화정도는 회전스크류 가동방식에 따라 다르게 나타났다. 또한 회전스크류 가동시 입도분포는 25.0mm에서 0.25mm까지 폭넓게 분포하는 반면에 미가동시에는 25.0mm에서 3.56mm까지 의 좁은 입도분포와 25.0mm이상의 입자크기에 집중되고 있다. 회전스크류 가동으로 건조효율에 미치는 효과를 회전스크류 미가동시와 비교하면 시간당 증발수분량은 364%, DS(Dry Solid)당 증발수분량은 356%나 증가한 것으로 평가되었다.