• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.359-360
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• 2006

Recently, a lot of work and interest has been devoted to the development of multiaxial fatigue parameters for fretting fatigue life prediction. Many of these parameters have been reviewed in the literature for simple geometries like a cylinder-on-flat contact configuration. The purpose of this study was to estimate fretting fatigue life using critical plane approach which is one of the multiaxial fatigue theories.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.554-558
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• 2002

A magnetostrictive sensor is used to measure stress waves propagating in a ferromagnetic cylinder without physical contact. The performance of a magnetostrictive sensor is affected most significantly by the bias magnetic field applied around the measurement location. The goal of this paper is to carry out the topology optimization of the bias magnet and yoke assembly to maximize the sensor output for traveling bending waves. We will use the multi-resolution topology optimization strategy to find the assembly of the bias magnet and the yoke that is easy to realize. The effectiveness of the present design is confirmed by an actual measurement of the sensor signal with the proposed bias magnet and yoke configuration.

• 한국정밀공학회지
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• 제24권4호
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• pp.123-130
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• 2007

Recently, a lot of work and interest have been devoted to the development of multiaxial fatigue parameters for fretting fatigue life prediction. In this study, the fretting fatigue lift and critical location ware estimated and evaluated through the multiaxial fatigue theories in a cylinder-on-flat contact configuration far Cr-Mo steel, SCM420, the material commonly is used in gears of the automobile and rollers of the conveyor. The strain-life curve was obtained from fatigue test for SCM420. The Fretting fatigue life and critical location were estimated through stress distributions, SWT-parameters and FS-parameters obtained from FEA. This paper showed possibility of applying multiaxial fatigue theories to fretting fatigue lift prediction comparing predicted life with experimental results.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.77-85
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• 1995

Among mechanical friction losses in an engine, the piston assembly and cylinder components accounts for the majority of the losses. The movable bore technique has been developed and turned out to be the most reliable technique in measuring the instantaneous friction of piston assembly. The weakness of this system, however, was the presence of the protruded top of movable bore necessary for pressure balancing. Because of the protruded part the piston could not be taken out without disassembling the crankshaft. Present study was carried out with a system of removable top of the movable bore so that it was possible to make frequent piston removals. The effects from engine speed, oil viscosity, engine load and elastic contact pressure of piston rings on the frictional characteristics have been evaluated with the improved equipment. Also, frictions of each member of piston assembly were measured.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1837-1839
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• 1997

This study presents the energy transfer of thermal arc in the circuit breaker with self-generation flow without puffer action. The phenomenon of pressure increase in the cylinder which encloses fixed contact was focused on and rising current stage was considered. Temperature and velocity of arc plasma were calculated by using energy balance equation and the amount of energy transfer due to convective flow was calculated.

• Tribology and Lubricants
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• 제16권3호
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• pp.182-187
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• 2000

In this paper the residual stresses on lubricated sliding surfaces were measured during break-in procedure and up to scuffing by the X-ray diffraction method. The cylinder-on-disk type tribometer was used with the line-contact geometry. Scuffing tests were done using a constant load. In the break-in procedure the loads were increased from very low values in several steps. It was found that the sliding surfaces with break-in represented relatively higher values of residual compressive stresser than those without break-in. The residual stresses below the surfaces showed the small amount of stress increases. The results of scuffing tests with and without break-in showed the same trends as break-in tests did. However, in case of tests with break-in procedure the stresses below the surfaces showed very large increases in the residual compressive stresses. From the tests of break-in and scuffing, it was found that the increases in scuffing lives were related with the increases of residual stresses on the lubricated sliding surfaces with break-in.

• 소성∙가공
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• 제7권6호
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• pp.594-602
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• 1998

The design analysis of axisymmetric, multi-stage deep drawing dies was performed using the rigid-viscoplastic finite element formulation. In the formulation the axisymmetric CFS algorithm was employed. Hill's non-quadratic normal anisotropic yield criterion and isotropic hardening rule were considered. For trial initial displacements and tool contact points. the geometric force equilibrium method was adopted. In order to see the validity of the formulation, the multi-stage deep drawing processes of shell-cylinder front part of hydraulic booster were simulated. The simulation showed good agreements with measurments and PAM-STAMP results.

• 대한기계학회논문집A
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• 제40권5호
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• pp.437-447
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• 2016

원자력 발전소의 반응로에 핵연료 봉으로 이루어진 집합체가 있으며 핵 연료의 연소를 통한 열을 이용하여 발전을 한다. 핵연료 봉은 핵연료와 그를 감싸는 피복관으로 이루어졌으며 연소되는 동안 서로의 상호작용에 대한 해석은 안전성을 평가함에 있어 중요한 사실이다. 본 논문에서는 핵연료와 피복관의 연소 상태에서 기계적 상호작용에 대한 해석 방법에 대하여 제시한다. 온도 해석에 있어서 핵연료와 간극 사이에서의 열전도도가 중요하며 간극 거리와 접촉여부에 따른 접촉 압력이 또한 중요 요소이다. 이에 간극 열전도도는 비결정론적이기 때문에 이를 해결할 수 있는 방법에 대하여 제시했다. 핵 연료의 열팽창에 따른 피복관과의 접촉을 해결하기 위한 계산을 수행하였고 그에 따라 접촉 시 발생하는 응력이 항복함수를 넘어 소성 변형이 일어날 경우 또한 고려하였다. 핵연료의 열팽창에 따라 피복관과 접촉에 의한 소성 변형을 해석하므로 핵연료 봉의 안정성을 평가할 수 있다. 이를 적용하기 위해 3차원 유한요소 모듈을 FORTRAN90을 이용하여 개발하였다. 핵연료와 피복관의 접촉에 의한 탄소성 변형을 주로 다루며 두꺼운 실린더를 통한 간단한 이론 모델을 제시하여 코드에 대해 검증을 실시하였다.

• Corrosion Science and Technology
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• 제14권4호
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• pp.177-183
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• 2015

Prestressed Concrete steel Cylinder Pipe (PCCP) is extensively used as seawater pipes for cooling in nuclear power plants. The internal surface of PCCP is exposed to seawater, while the external surface is in direct contact with underground soil. Therefore, materials and strategies that would reduce the corrosion of its cylindrical steel body and external steel wiring need to be employed. To prevent against the failure of PCCP, operators provided a cathodic protection to the pre-stressing wires. The efficiency of cathodic protection is governed by the anodic performance of the system. A mixed metal oxide (MMO) electrode was developed to meet criteria of low over potential and high corrosion resistance. Increasing coating cycles improved the performance of the anode, but cycling should be minimized due to high materials cost. In this work, the effects of $RuCl_3$ concentration on the electrochemical properties and lifespan of MMO anode were evaluated. With increasing concentration of $RuCl_3$, the oxygen evolution potential lowered and polarization resistance were also reduced but demonstrated an increase in passive current density and oxygen evolution current density. To improve the electrochemical properties of the MMO anode, $RuCl_3$ concentration was increased. As a result, the number of required coating cycles were reduced substantially and the MMO anode achieved an excellent lifespan of over 80 years. Thus, we concluded that the relationship between $RuCl_3$ concentration and coating cycles can be summarized as follows: No. of coating cycle = 0.48*[$RuCl_3$ concentration, $M]^{-0.97}$.

• 한국수소및신에너지학회논문집
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• 제24권6호
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• pp.535-542
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• 2013

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor using bed inserts, effect of bed insert geometry on CO conversion of WGS catalyst was measured and investigated. Small scale fluidized bed reactor was used as experimental apparatus and tablet shaped WGS catalyst and sand particle were used as bed materials. The cylinder type and the spring type bed inserts were used to hold the WGS catalysts. The CO conversion of WGS catalyst with the change of steam/CO ratio was determined based on the exit gas analysis. Moreover, gas flow direction was confirmed by bed pressure drop measurement for each case. The measured CO conversion using the bed inserts showed high value comparable to previous results even though at low catalyst content. Most of input gas flowed through the bed center side when we charged tablet type catalyst into the cylinder type bed insert and this can cause low $CO_2$ capture efficiency because the possibility of contact between input gas and $CO_2$ absorbent is low in this case. However, the spring type bed insert showed good reactivity and good distribution of gas, and therefore, the spring type bed insert was selected as the best bed insert for SEWGS process.