• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.367-370
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• 2012

본 연구는 하나의 장치 내에서 "싸이클론-관성충돌-여과포 집진"이라는 다단 제진 단계가 동시에 이루어져 입경 분포별로 순차적인 제진이 가능한 멀티 집진기의 처리가스 제어 효율을 극대화시킬 수 있는 기류 흐름을 얻기 위한 최적화 설계 조건을 검토하는 것이다. 우선 1단계 제진 과정인 원심력을 이용하여 조대입자의 유선 이탈을 촉진시킬 수 있는 사이클론 유동을 최적화시키기 위한 집진기 입구 형상 설계 검토를 위해 수치 해석적 연구를 수행하였다. 그 결과, 멀티집진기 입구 형상을 일반적인 설계 방식인 접선 유입식으로만 설계한 것에 비해 선회류를 한번 더 가속화시킬 수 있는 가이드 베인을 추가로 설계한 경우 선회류의 pitch가 짧고 강하게 형성되어 사이클론부에서 조대입자의 유선 이탈을 촉진시키는데 매우 효과적인 것으로 예측되었다. 단, 사이클론부 하단 벤츄리 형상으로 인해 약 4~5 m/s의 강한 하향 흐름이 호퍼 하단까지 형성되고 있어 탈리 분진의 재비산 문제가 발생할 가능성이 크므로 벤츄리 형상 설치 유무에 대한 영향도 추가적으로 연구가 필요할 것으로 판단된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.97-102
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• 2013

A prestudy on expendable turbine engine for high-speed vehicle was conducted. After two possible mission profiles were established to decide the engine requirements, design point analysis was performed with the values of design parameter which were obtained from similar class engines, references, etc. The results showed that specific net thrust and specific fuel consumption with turbine inlet temperature of 3,600 R are 2,599.4 ft/s and 1.483 lb/(lb*h) respectively at the flight condition of sea level, Mach 1.2. It was also found that major design parameters for determining maximum net thrust were turbine inlet temperature for low supersonic and transonic flight speed and compressor exit temperature for high supersonic flight speed from the results of performance analysis on the two possible mission profiles. In addition, simple turbojet engine with an axial compressor, a straight annular combustor, an one stage axial turbine and a fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost lightweight turbine engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.805-814
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• 2011

Aluminum plate-fin heat exchangers (ALPHEs) are widely used in petroleum and gas-treated processes. The performance of the ALPHE is strongly dependent on the distribution characteristics of the header and the distributors of each fluid. In this paper, we define the aspect ratio in the side-entry type distributor and analyze the distribution characteristics using CFD-based numerical methods. The phenomena of velocity deviation and distribution with the aspect ratio and the inlet Reynolds number were analyzed by applying relative and absolute maldistribution parameters, and an optimum aspect ratio with the inlet Reynolds number was presented.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.997-1002
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• 2012

Emission regulations have been strengthened step by step for marine engines. A noble measure is required both inside and outside of the combustion chamber. The combustion characteristics in cylinder have a very close relationship with the exhaust emission characteristics. Injection valve and nozzle hole geometry is an important factor for combustion. The study to improve the spray characteristics has concentrated on nozzle inlet geometry and nozzle hole diameter, but the exit geometry has not considered. In this study the nozzle exit angle variation was tested. The results show that the angle between $30^{\circ}$ and $60^{\circ}$ is more effective than the other cases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.6
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• pp.324-330
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• 2013

The main objective of this work is to experimentally investigate the effect of inlet geometries on the distribution of two-phase annular flow at header-channel junctions simulating the corresponding parts of compact heat exchangers. The cross-section of the header and the channels were fixed to $16mm{\times}16mm$ and $12mm{\times}1.8mm$, respectively. Experiments were performed for the mass flux and the mass quality ranges of $30{\sim}140kg/m^2s$ and 0.3~0.7, respectively. Air and water were used as the test fluids. Three different inlet geometries of the header were tested:no restriction (case A), a single 8 mm hole at the center (case B), and nine 2 mm holes around the center (case C) at the inlet, respectively. The tendencies of the two-phase flow distribution were different, in each case. For cases B and C (flow resistance exists), more uniform flow distribution results were seen, compared with case A(no flow resistance), due to the flow pattern change to mist flow from annular flow at the inlet, and the flow recirculation near the end plate of the header.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2000-2004
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• 2008

본 지침은 하천 횡단시설물을 설치하는 경우, 효율적인 어류 이동을 위한 어도 설계 및 설치 기법을 제시함에 있다. 어도의 설계 조건으로는 상류 이동 어류가 어도입구 이외의 장소에 모여들지 않아야 하고, 이동 어류의 손상이나 극도의 피로를 피하도록 하여야 하며, 어도의 입구에 모인 어류의 어도로의 유인이 용이하여야 한다. 또한 어류가 쉽고 안전하고 신속하게 상류 이동할 수 있어야 한다. 주요 내용으로, 어도의 하류측 돌출 조건, Set back식 어도, 하류 턱 설치, 어도의 하류 끝단의 설계, Notch부의 단면 형상, 어도의 접속 조건, 로프 설치 조건, 어도의 하류부 설치 기법, 강하용 어도의 설계 기법 등을 제시하였다.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.828-831
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• 2011

본 논문에서는 피에조 잉크젯 헤드의 액적 토출 형상에 대해 전산해석을 통하여 연구하였다. 열유체 해석 전용 프로그램인 FLUENT를 이용하여 에틸렌 글리콜이 잉크젯 헤드의 노즐에서 토출될 때의 형상을 전산모사하였다. 노즐 출구에서 메니스커스 변위의 시간에 따른 변화를 직접 측정하여 노즐 입구의 속도분포를 예측하고 이를 해석의 입력 자료로 사용하였다. 측정치와 해석치를 비교한 결과 전산해석이 측정치의 액정 형성 과정을 잘 모사함을 알 수 있었다.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.746-752
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• 2000

A study on discharge characteristics of a rotating discharge hole is very important to enhance the performance of an induction motor which have external forced cooling system. The discharge characteristics of rotating discharge holes are influenced by rotating speed, length-to-diameter ratio, inlet shape of rotor holes, etc. An experimental study on the effect of chamfered inlet edge of rotor inlet part with various depth-to-diameter and inlet chamfered edge angle is conducted. Depth-to-diameter ratios range from 0 to 0.5 and inlet chamfered edge angle range from 0 to 60. As a result, there is an optimal design point of inlet chamfered edge depth. And the inlet edge angle far maximum discharge coefficient is influenced mainly by the rotating speed of discharge holes.

• The KSFM Journal of Fluid Machinery
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• v.10 no.6
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• pp.44-49
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• 2007

In this paper, effects of inlet shape on the performance of a submerged cargo pump were numerically studied using a commercial CFD code CFX. The inlet shape, especially the gap between pump and suction well, is an important parameter in a point of view of performances of submerged cargo pump due to its effects on the residual and also hydraulic performance of the pump, respectively. To know the optimized gap, the overall performance degradations were calculated with the gap. In addition to that, the flow field through the gap was investigated to explain the effect of velocity non-uniformity on the performance of the pump impeller.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.5-5
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• 2007