• 자원리싸이클링
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• 제14권2호
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• pp.3-9
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• 2005

폐자동차 ASR으로부터 염소성분을 제거하기 위하여 풍력선별 및 비중선별 실험을 수행하였다. 또한, ASR플라스틱만을 분리하여 물을 매체로 한 비중선별을 실시하였다. ASR 시료는 모두 8 mm이하로 재분쇄하여 선별실험에 사용하였으며, 플라스틱은 3가지 입도로 나누어 비중선별 실험을 하였다. 풍력선별은 공기유량 9~20 M$^3$/hr 범위의 1단계와 공기유량 25~34 M$^3$/hr 범위의 2단계로 나누어 실시하고 각 산물의 비율과 재질분포를 조사하였다. 1단계 풍력선별후 underflow 산물의 비율은 62~66%인 것으로 나타났으며, 공기유량이 큰 2단계 풍력선별에서는 overflow 산물의 비율이 크게 증가하였다. 폐플라스틱만을 대상으로 한 비중선별 실험결과 부유물질이 침강물질에 비해 다소 많게 나타났으며, 염소함량에 있어서는 최대 수백개의 염소함량 차이를 보여 순수 플라스틱의 경우 매우 우수한 염소함유 재질의 분리효과를 얻을 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.460-465
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• 2003

Microgravity experiments were conducted to determine the effect of liquid and gas superficial velocities on flow behaviors. Flow behaviors observed under microgravity conditions can be classified into five flow patterns: bubble. Taylor bubble, slug, semi-annular and annular flows. Transition boundary between four flow patterns could be determined by drift-flux model. It was also found that the effect of gravity and pipe inclination on flow pattern transition was not significant in the inertia dominant region.

• 설비공학논문집
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• 제8권4호
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• pp.537-549
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• 1996

A numerical study of heat and mass transfer has been carried out for a frost formation process on a circular cylinder in a cross flow including the effect of buoyancy. Studies include cases of low and high Reynolds number flows. The effect of normal velocity at the surface which is produced due to mass transfer was included in the analysis as well as heat transfer contribution generated due to mass transfer. Variations of heat transfer and frost growth both in time and in the circumferential direction have been obtained for various buoyancy parameters. The effect of flow directions(identical or opposite directions to the gravity) has been studied to yield different frost growth. Our results have been compared with existing experimental data and are in good agreement. Buoyancy analyses for a high Reynolds number flow agree with full numerical solutions for the case of having the same flow direction as gravity. However, for the opposite direction case, the boundary layer analyses would not be applicable to predict frost growth except the region near the stagnation point.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.1111-1115
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• 2008

The relative magnitudes of the individual terms of the momentum equation are analyzed and compared by the analytical methods in open channel flow. The temporal variations of each term(local acceleration term, convective acceleration term, pressure force term, gravity force term, and friction force term) are analyzed for the influence factors to runoff expressed by the parameters of the momentum equation, stream slopes and roughness coefficients. The magnitudes of each term vary with the channel characteristics, especially when the roughness coefficients are dominant or for the mild stream slopes the pressure term can not be negligible. As a result of the characteristics of momentum equation in open channel flow, the acceleration terms are very small compared with the other terms. The magnitudes of local acceleration and convective acceleration offsets each other. The peak time of each term except the gravity term coincides with inflection point of the hydrograph rising limb each other.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.43-46
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• 2003

We consider influences of the aperture variation and the ambient groundwater flow on the migration of DNAPL within a fracture network. In context of a modified invasion percolation (MIP) growth algorithm, we formulate a mechanistic model that includes capillary and gravity forces as well as viscous forces within the DNAPL and the ambient groundwater. The MIP model is verified against laboratory experiments, which is conducted using a two-dimensional random fracture network model. The results show that the aperture variation and ambient groundwater flow can be significant factors controlling DNAPL migration path within fracture networks.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.505-506
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• 2006

This study is focused on the manufacturing technique of powder injection molding of watch case made from zirconia powder. A series of computer simulation processes were applied to the prediction of the flow pattern in the inside of the mould and defects as weld-line. The material properties of melted feedstock, including the PVT graph and thermal viscosity flowage properties were measured to obtain the input data to be used in a computer simulation. Also, a molding experiment was conducted and the results of the experiment showed a good agreement with the simulation results for flow pattern and weld line location. On the other hand, gravity and inertia effects have an influence on the velocity of the melt front because of the high density of ceramic powder particles during powder injection molding in comparison with polymer's injection molding process. In the experiment, the position of the melt front was compared with the upper gate and lower gate positions. The gravity and inertia effect could be confirmed in the experimental results.

• 한국수소및신에너지학회논문집
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• 제34권4호
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• pp.342-349
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• 2023

In this study, a numerical simulations were conducted to analyze the phase change behavior of a liquid hydrogen storage container. The effects of gravity direction and hydrogen filling rate on boil-off gas (BOG) in the storage container were investigated. The study employed the volume of fluid, which is the phase change analysis model provided by ANSYS Fluent (ANSYS, Canonsburg, PA, USA), to investigate the sloshing phenomenon inside the liquefied hydrogen fuel tank. Considering the transient analysis time, two-dimensional simulation were carried out to examine the characteristics of the flow and thermal fields. The results indicated that the thermal flow characteristics and BOG phenomena inside the two-dimensional liquefied hydrogen storage container were significantly influenced by changes in gravity direction and hydrogen filling rate.

• 한국항해항만학회지
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• 제27권6호
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• pp.677-682
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• 2003

The long-period gravity wave, the wave period from some ten seconds to some minutes, induces not only the big sway of a ship moored and berthed in the harbor due to the horizontal long-distance motion of a water but also strong exfoliated flow and vortices near the harbor entrance. They muse serious problems on the safety navigation of vessels entering and leaving the harbor, but this gravity wave has not been searched sufficiently yet. Then it is quite important to reveal the characteristics of this long-period gravity wave ana to solve various problems induced by this wave. The long-period gravity wave measurement system with arrayed buoys installed the kinematic GPS was already proposed, which provides the precise propagating direction of the long-period gravity wave. In this paper, the observation results of the wave measurement system are shown by the MUSIC method And the propagating wave direction was estimated precisely enough in comparison with other results used other method.

• 한국방재학회 논문집
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• 제4권1호
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• pp.1-14
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• 2004

본 연구의 목적은 무엇보다도 콘크리트중력식 댐의 내진안전성 평가방법을 정립하는 데에 있다. 그렇게 하기 위하여 지진시 구조물의 거동을 파악하고 내진성능을 평가해야 한다. 본 연구에서는 구조해석 프로그램을 사용한 동적해석을 통하여 지진시의 피해상황을 알아보았다. 물의 중량으로 인하여 댐에 가해지는 동수압은 부가질량법을 이용하여 계산하였다. 본 연구에서 알아낸 바에 의하면 지반상태에 따라 경계조건을 부여해 주는 것이 필요하며 특히 댐의 모양이 불균일하거나 갑작스런 기하학적인 변화가 있을 때에는 댐의 상하류방향 지진 만이 아닌 댐축방향 지진에 대한 해석이 반드시 필요하다는 것이 밝혀졌다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.522-527
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• 2001

Comprehensive numerical computations are made of side-heated squire cavity which is exposed to zero mean g-jitter. Numerical solutions are acquires to the governing two-dimensional Navier-Stokes equations for a Boussinesq fluid. When the system is exposed to pure sinusoidal g-jitter inclined to the vertical axis, in spite of zero mean gravity there exist non zero net flow fields [8]. The resonance phenomenon are observed in moderate Rayleigh number. And, by comprehensive numerical work, unlike[5], it is found that they are related with the overshoot phenomenon of the sudden gravity up problem.