• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.162.1-162.1
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• 2010

Cavitation phenomenon has long been a difficult problem that regarded as negative event to fluid machines or industrial facilities. In the latest, however, some engineers became to understand the power of cavitation and use it to cleaning wall after developing cavitation nozzle. In this paper, we introduce new concept for power-generation system using cavitation jet flow maid by nozzle and impulse turbine in vacuum condition. The vacuum needed to make cavitation is generated naturally by Torricelli's vacuum, 10.23m effective head drop without additional power. We analyzed water's boiling and the steam's mean free path according to vacuum purity levels for nozzles and turbine blades. The nozzles make water accelerate in the neck and boil in expansion section of the nozzles. The shape of the impulse turbine is designed for absorption of the molecule's kinetic energy of the steam.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.48-53
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• 2003

The steel slag, a by-product which is produced on the process of manufacturing steel by refining pig iron is mainly used as road materials after aging it. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the volume expanded. Due to this reason it prevents steel slag from being used as aggregate of concrete. But steel slag used in this study is controled by a air-jet method which rapidly cools substance melted at a high temperature. Rapid cooling prevents from generating of free-CaO in steel slag. In this study, it was investigated that steel slag manufactured by air-jet method affects on concrete in the freezing and thawing. As results of this study, concrete mixed with steel slag was worse in the freezing and thawing than concrete mixed with sand in spite of using air entraining agent. To obtain durability of concrete in the freezing and thawing, it is desirable to mix 50% of steel slag in concrete per unit weight of volume.

• 한국안전학회지
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• 제9권4호
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• pp.77-84
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• 1994

A study is performed in order to design a effective ventilation equipment for the pollutants in workshop. The procedure has been used to calculate the flow in a confined rectangular space channel. A cross free stream is flowed from open space and jet stream including pollutants is injected from bottom area. Calculation results shows a wake region which exists immediarely downstream of the jet discharge and are compared with the experimental data. Calculation data are in good agreement with experimental results. A wake plays an important role on a stagnation of the pollutants. Thus ventilation equipment has to be designed without a stagnation region which give rise to concentration stratification. In this study, calculation parameters are the position and velocity of pollutants and fresh air from cross free stream. It is concluded that more measurements of local velocities, temperatures and concentrations of the pollutants.

• 한국가스학회지
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• 제7권1호
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• pp.41-46
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• 2003

14atm, 233K의 아세틸렌 기체를 자유팽창 시켜서 생성한 아세틸렌 cluster의 상과 온도 변화를 실험적으로 측정하였으며, cluster를 여러 겹의 shell로 나누어 취급하고 각 shell 마다 증발과 열전도 현상에 근거한 온도계산을 하는 모델링을 적용하여 이론적인 온도를 구하고 실험값과 비교함으로써, 생성된 cluster의 크기를 4.88$\mu$으로 결정하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.107-109
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• 2003

We propose a wall distance free one-equation turbulence model. The model is organized in an extremely simple form. Only a few model constants were introduced into the model. The model is numerically tough and easy-of-use. The model also demonstrated the ability to simulate the laminar to turbulent flow transition. The model has been applied to the channel flow, the plane jet, the backward facing step flow, the flat plate boundary layer, as well as the flow around the 2D airfoil at large angles of attack, which obtained satisfactory results.

• 대한기계학회논문집B
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• 제28권8호
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• pp.895-901
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• 2004

Single-phase convection and nucleate boiling heat transfer were locally investigated for confined planar water jets. The detailed distributions of the wall temperature and the convection coefficient as well as the typical boiling curves were discussed. The curve for the single-phase convection indicated the developing laminar boundary layer, accompanied by monotonic increase of the wall temperature in the stream direction. Boiling was initiated from the furthest downstream as heat flux increased. Heat transfer variation according to the streamwise location was reduced as heat flux increased enough to create the vigorous nucleate boiling. Velocity effects were considered for the confined free-surface jet. Higher velocity of the jet caused the boiling incipient to be delayed more. The transition to turbulence precipitated by the bubble-induced disturbance was obvious only for the highest velocity, which enabled the boiling incipient to start in the middle of the heated surface, rather than the furthest downstream as was the case of the moderate and low velocities. The temperature at offset line were somewhat tower than those at the centerline for single-phase convection and partial boiling, and these differences were reduced as the nucleate boiling developed. For the region prior to transition, the convection coefficient distributions were similar in both cases while the temperatures were somewhat lower in the submerged jet. For single-phase convection, transition was initiated at $x/W{\cong}2.5$ and completed soon for the submerged jet, but the onset of transition was retarded to the distance at $x/W{\cong}6$ for the fee-surface jet.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.399-400
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• 2014

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2000년도 춘계학술발표논문집
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• pp.111-111
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• 2000

• 태양에너지
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• 제18권3호
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• pp.217-228
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• 1998

축류비가 5이고 형상비가 7인 장방형(長方形) 노즐을 사용하여 연직 상향의 3차원 자유 충돌 수분류계를 구성하였다. 수평 충돌판에 상향의 장방형 충돌수분류가 충돌할 때, 보조수를 동반하지 않은 단일수분류 및 보조수를 동반하는 수분류에 대하여 노즐-충돌판 사이의 거리, 노즐출구 속도를 변수로하여 노즐의 긴변 방향과 짧은 변 방향에 대하여 전압 및 정압 분포를 측정하였다. 이때 충돌판상에서 정압이 영이 되는 국소 위치까지의 거리인 충돌 반폭을 구하고, 최고 압력을 나타내는 정체점을 기준으로 무차원 정압 분포식을 제시하였다. 또한 각 실험조건에서 정체점상에서의 충돌속도를 구하였으며, 충돌속도는 노즐-전열면간 거리가 증가함에 따라 감소하며 그 감쇄율은 삼차원 자유 분류의 특성감쇄 영역의 유동 특성을 갖는다.

• 한국추진공학회지
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• 제9권2호
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• pp.97-104
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• 2005

많은 장점에도 불구하고 유동함수를 이용한 수치해석용 격자생성 좌표변환기법의 단점은 저속영역에서의 격자간격이 고속영역에 비해 상대적으로 큼에 따라 수치적 처리에 많은 오차를 내포하고 있다는 점이다. 본 연구에서는 이러한 저속영역에서의 단점을 보완하기 위하여 격자간격을 속도크기 및 영역에 따라 적절히 조절할 수 있도록 수학적으로 변형된 압축성 유동함수를 이용한 좌표변환기법을 제안하고 가스터빈엔진에 주로 적용되는 유동모델로서 동심원상 두개 이상의 난류제트혼합유동에 대해 적용하였으며 해당 실험치, 즉 축 방향 평균속도분포, 난류운동에너지, 그리고 난류전단응력분포와 비교하여 난류운동에너지가 약간 과소평가 된 대칭축을 제외한 혼합경계층 내에서 $3.5\%$ 이내의 신뢰성을 확보하였다. 본 기법은 특히 터보팬엔진에 대한 내부흐름들의 혼합유동을 규명하거나 또는 난류전단응력에 의한 제트소음발생 및 저감방법을 도모하는데 유용하게 활용될 것으로 기대된다.