• 대한기계학회논문집
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• 제10권1호
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• pp.50-55
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• 1986

본 연구에서는 경계면에 맞춘 좌표계를 이용한 mapping을 통하여 37개봉으로 구성된 유로에서의 전달현상을 분석하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.140-145
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• 1998

In this study, analysis for fatigue crack propagation behavior of interface and aroud interface under rotary bending stress. Though K values are nearly the same in around interface by BEM 2-D, fatigue crack propagated H.A.Z. Around Interface crack propagation speed is m=0.678 in H.A.Z by Paris' law. In this case(friction welded materials: STS304, SM15C), fatigue crack growth is considered SM15C metal microstructure and elastic flow from this result. Result is more metal microstructute dependence than stress dependence by analysis (BEM 3-D, BEM 2-D) and fatigue crack propagation

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.145-151
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• 1997

PAG(Polyalkylene Glycol) and esters are tested with HFC-134a as a refrigeration oil. This investigation enhances the testing method by taking the compressor's environment into account. A testing environment charged with refrigerant gas more closely simulates the conditions of a compressor. The friction coetTicient of the PAG/HFC-134a system is similar to that of the mineral oil/CFC-12 system at operating conditions. Ester oils are preferable at the start & stop condition in the lubricity aspect. PAG shows good lubricity in conditions of extreme contact pressure. Consequently, this test provides reliable results on compressor lubricity of refrigeration oils with HFC-134a. It suggests a methodological way for the proper selection of refrigeration oils that may improve the durability and performance of a compressor.

• 대한기계학회논문집B
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• 제27권3호
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• pp.311-318
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• 2003

The present work evaluates the effects of mixing vane shape on the flow structure and heat transfer downstream of mixing vane in a subchannel of fuel assembly. by obtaining velocity and pressure fields. turbulent intensity. flow-mixing factors. heat transfer coefficient and friction factor using three-dimensional RANS analysis. Four different shapes of mixing vane. which were designed by the authors were tested to evaluate the performances in enhancing the heat transfer. Standard k-$\varepsilon$ model is used as a turbulence closure model. and. periodic and symmetry conditions are set as boundary conditions. The flow blockage ratio is kept constant. but the twist angle of mixing vane is changed. The results with three turbulence models were compared with experimental data.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.181-184
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• 2014

Loose Parts Monitoring System(LPMS) monitors loosened or detached parts and foreign parts inside the pressure boundary of a reactor coolant system (RCS). It is difficult to discriminate valid signal from LPMS alarms at full power since the signal pattern by thermal shocks and structure friction are similar to those by loose metal impacts. In addition, It is more difficult to discriminate the impact signals induced by the rod driving, sensor hard-line movement and loosened component since they have similar frequency characteristics with valid signals. This paper classifies the signal patterns by analyzing actual LPMS signal captured during nuclear power plant operation.

• Journal of Magnetics
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• 제21권1호
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• pp.153-158
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• 2016

This paper aims to discuss the Non Darcy boundary layer flow of non-conducting viscous fluid with magnetic ferroparticles over a permeable linearly stretching surface with ohmic dissipation and mixed convective heat transfer. A magnetic dipole is applied "a" distance below the surface of stretching sheet. The governing equations are modeled. Similarity transformation is used to convert the system of partial differential equations to a system of non-linear but ordinary differential equations. The ODEs are solved numerically. The effects of sundry parameters on the flow properties like velocity, pressure, skin-friction coefficient and Nusselt number are presented. It is deduced the frictional resistance of Lorentz force decreases with stronger electric field and the trend reverses for temperature. Skin friction coefficient increase with increase in ferromagnetic interaction parameter. Whereas, Nusselt number decrease.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.514-521
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• 2008

Many research works for improving a boundary lubrication performance have been executed by using solid lubricants, and been tried to apply an engine lubrication. However those general lubricants have not been applied on engines due to the extreme conditions such as very high temperature and pressure during combustion process in a cylinder. In this study a lubricant containing copper alloy nano-powder is applied on a diesel engine driven by an electric motor. Torques and shaft vibrations are measured, then an engine friction loss and rotating stability are assessed. The results show that the frequency of the vibration is about the same as that of a general lubricant, but the amplitudes in the both X and Y direction are reduced as well as the friction loss is reduced.

• Structural Engineering and Mechanics
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• 제12권6호
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• pp.595-614
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• 2001

This paper studies the behaviour of a homogeneous cable in a horizontal rigid duct and loaded by an axial compressive force. This behaviour is characterized by spatial buckling modes, named sinusoidal and helical, due to friction and total or partial cable locking. The evaluation of critical buckling loads involved by drilling technology has been studied by many authors. This work presents a new formulation, taking the friction effects into account, for the transmission of the axial load during the postbuckling process. New analytical expressions of pitches in both buckling cases are also given. A life-sized bench is presented, which permits to study the laying of optical fiber cables by squeezing them into an underground duct. Finally, analytical solutions are compared with experimental tests and finite element simulations.

• 한국안전학회지
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• 제29권1호
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• pp.25-30
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• 2014

This paper deals with a numerical study on the deformation of a mono tendon anchor head. The anchor head is used to introduce the compression to concrete, and consists of wedges and a head. All kinematics, material and contact nonlinearity are included in the precise analysis of a mono tendon anchor head. A numerical study on a mono tendon anchor head is performed to investigate effects of friction and eccentricity of load by ABAQUS. From the numerical results, it is verified that the deformation of a mono tendon anchor head is affected by characteristics of materials, boundary condition between wedge and anchor head, eccentricity of load, etc.

• 한국구조물진단유지관리공학회 논문집
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• 제13권6호통권58호
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• pp.176-182
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• 2009

단조롭고 자연친화적이지 못한 기존 연안블록의 설계 및 시공으로 인하여, 연안침식방지 블록이 효과적으로 제 기능을 발휘하지 못하고 또 다른 피해가 발생되고 있다. 국민소득의 증대와 Waterfront 개념의 빠른 확산으로 연안 어항의 낙후된 시설개선 등에 많은 사업이 추진되고 있으나 이러한 용도에 맞는 자연 친화형 구조물이 개발된 바 없어 기존의 Solid Block, Igloo Block, Tunnel Block 등이 일부 현장에 적용되고 있는 실정이다. 선박이 계류하는 안벽이나 물양장 등에서 항내 진입파와 항파 등으로 인한 반사파의 발생에 의한 공진현상으로 항내파고가 높아져 정온도유지가 어렵고 선박의 계류 및 하역에 지장을 주게 되며, 선박과의 충돌 발생으로 인한 소형선박의 손괴 발생율이 높은 실정이므로 새로운 형태의 블록(Block)개발이 필요하다. 이에 따라 개발한 C.E.(Coastal Environments)블록을 현장에서 사용하기 위해서는 전단키 부분의 내하력 평가가 요구 된다. 따라서, 본 연구는 C.E. 블록의 연결부 시험편을 제작하여 C.E.블록 경계면의 마찰실험을 실시하였으며, 실험에서 얻은 C.E.블록 연결부의 마찰계수를 유한요소 해석에 사용하여 C.E.블록의 블록과 블록 접촉면의 마찰 계수를 산정하고자 한다.