• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제25회 춘계학술대회
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• pp.183-189
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• 1997

This paper presents the motion of dynamically loaded journal in the connecting rod bearing of reciprocating internal combustion engine. Journal motions in engine bearings have been composed of two components, which was rotational and translational motion. Early study of journal locus in engine bearing had been performed on each motion. This paper has been considered two motions simultaneously. Reynolds equation including the squeeze effect has been analyzed using the ADI method, and real engine bearing and crankshaft system has been considered to calculate the cyclic external force. The equations of journal motion have been derived and then the numerical integration of these equations performed by 4th order Runge-Kutta method. This paper gives various journal orbits in connecting rod bearing depending on cyclic external forces, rotating speeds, and bearing parameters.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.656-662
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• 2011

최근들어 철도차량 기술은 비약적으로 발전하고 있지만 승차감과 진동 등의 문제는 앞으로도 계속 연구해야 할 과제로 남아있다. 서울시 7호선 전동차(SR001)에 적용된 공기압축기는 유지보수성 및 점검의 편리함을 고려하여 오일프리 왕복동식 공기압축기를 적용하였다. 하지만 왕복동식 공기압축기는 피스톤의 왕복 운동에 의해 공기를 압축하고 그 관성의 힘 때문에 압축기 및 주위 구조물에 진동을 전파한다. 그 전파되는 진동을 최소한으로 줄이기 위해 오일프리 왕복동식 공기압축기의 마운팅 브라켓에 대한 최적설계를 통해 진동저감 효과를 볼 수 있었고, 그와 더불어 공기압축기 작동시 발생되는 진동을 측정하여 나온 결과 값을 토대로 진동에 대한 주파수 스펙트럼을 비교 분석하였다. 본 연구에서는 설계치와 실험결과의 차이를 분석하여 왕복동식 공기압축기의 진동전파 과정을 파악하고, 진동이 전달되는 것을 최소화 하여 진동저감을 위한 대책을 고찰하였다.

• 대한기계학회논문집
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• 제18권1호
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• pp.139-149
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• 1994

A numerical simulation of unsteady axisymmetric turbulent flow was performed for a reciprocating engine including port/valve assembly. The governing equations based on a nonorthogonal coordinate formulation with Cartesian velocity components were used and discretised by the finite volume method with non-staggered variable arrangements. The modified $\kappa-\xi$. turbulence model which included the effect of compressibility was used. The results of twodimensional transient calculation for the axisymmetric configuration were compared with the experimental data. Although slightly low rms velocity was predicted compared to the experimental data, predicted velocity distributions at the valve exit and in-cylinder region showed good agreements with the experimental data. The flow at the valve exit was separated at the same valve lift position with the experimental data. Two vortices incylinder region were generated during the initial intake process. The clockwise main vortex became strong and moved upward to the top wall. The counter-clockwise second vortex became weak and stick to the upper left corner of the cylinder. After middle intake process, new vortex adjacent to upper cylinder wall appeared by the piston motion and therefore, the in-cylinder flow was formed into three vortices. The cylinder pressure just before bottom dead center of piston was higher than inlet pressure and then the reverse flow occured at the valve exit. The in-cylinder flow characteristics were strongly dependent on piston motion, but insensitive to valve motion.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.807-810
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• 1995

The effects of weae particles on the friiction and wear behavior of metals in dry sliding conditions are presented. The tribological test were performed using pure metal specimens which were selected based on their degrees of compatibility and hardness ratio. Friction and wear experiments were conducted using both pin-on-disk and reciprocating pin-on-plate type tribotesters to investigate the effect of motion history. Experimental results show that in the case of dry sliding the frictional behavior observed during pin-on-disk test differed form that of pin-on-reciprocator test for the given set of material pairs. The friction coefficient and wear rate were found to be higher for the pin-on-disk tests. It is suspected that the sliding motion of the pin affects the wear particle dynamics, which in turn influences the frictional behavior. The effect of material pair properties seemed to be relatively smaller than that of wear particles. The results of this paper is expected to aid in the design of mechanical systems for best tribological performance.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.498-505
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• 2008

Many researches have been studied on in-cylinder flow as one of dominant effects for an engine combustion. The combustion phenomena of reciprocating engine is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of their relationship is not well known. To know this relationship definitely, this paper describes analytical results of the tumble motion, swirl motion, turbulence intensity, turbulence inside the cylinder of marine engine. 3-D computation has been performed by using STAR-CD solver and es-ice.

• 한국기계연구소 소보
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• 통권19호
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• pp.155-161
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• 1989

Generally cam-follower systems consist of two elements: Cam is for rotating motion and follower for reciprocating motion. Depending on the shape of cam and type of follower, the motion of cam-follower system is determined. Thus design process and analysis process must be well defined. The design process means to find the coordinates of cam shape which can be defined the given motion of follower and the analysis process means to determine the motion curve of follower corresponding to the given cam based on the dimensions of a cam-follower system. This paper consists of two parts : One is for development of a numerical method for design and analysis of cam-follower systems, the other is for development of a CAD program and its application. As the second part of the paper, the structure of a CAD program is introduced. Four data files are used in the program where the design process and the analysis process are carried out interactively to en hence its availability to the industrial applications. The first part of the paper 'presents the iterative contact method which can determine the contact points and their angles between cam and roller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.266-271
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• 1989

In eliminating the nonliner charateristics such as piston displacement drift and difference in speeds of the reciprocating motion due to their nonsymetrical structure of single rod cylinder, modelling was carried out by additional outside disturbance, suggest the position control of single rod cylinder servosystem using VSS and compared with PD control of fixed structure system.

• Journal of Advanced Marine Engineering and Technology
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• 제16권1호
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• pp.27-34
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• 1992

In eliminating the nonlinear characteristics such as piston displacement dift and difference in speeds of the reciprocating motion due to their nonsymetrical structure of single rod cylinder, the linear model can be given by equivalent outside disturbance, etc. The position control method of single rod cylinder servosystem using the sliding mode control of VSS was suggested and the good results without off-set are compared with PD control of fixed structure system.

• 감성과학
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• 제9권2호
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• pp.133-140
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• 2006

본 연구에서는 의복 착용 시 직물이 스치면서 발생하는 왕복마찰음에 대한 물리적 소리특성과 주관적 감각을 고찰하기 위해, 왕복운동을 이용한 직물마찰음발생장치를 개발하고 이 장치를 이용하여 5가지 직물의 왕복마찰음을 녹음한 후, 총음압(LPT), 음압차(${\Delta}L$), 주파수차(${\Delta}f$)를 계산하였다. 왕복마찰음에 대한 주관적 감각은 7개의 소리감각(부드러움, 시끄러움, 날카로움, 맑음, 거침, 높음, 유쾌함)에 대하여 의미미분척도로 평가되었다. 나일론 태피터와 폴리에스테르 레노 직물의 왕복마찰음은 높은 LPT를 나타내어 시끄럽고 날카롭고 거칠며 불쾌한 소리로 인지되었다. 반면 LPT와 ${\Delta}f$의 값이 작은 폴리에스테르 울트라스웨이드와 실크 크레이프드신 직물의 왕복 마찰음은 부드럽고 조용한 소리로 평가되었다. 마찰방향(왕복 방향, 한 방향)에 따른 직물의 마찰음 비교시, 왕복 방향 마찰음은 한 방향 마찰음보다 더 날카롭고 시끄럽고 거칠게 인지되었으며 마찰방향에 상관없이 LPT가 소리감각을 예측하는 중요한 요인으로 나타났다.

• 한국정밀공학회지
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• 제29권1호
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• pp.64-71
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• 2012

In this paper, a parallel manipulator is comprised of two sliders and four links. Sliders execute a linear reciprocating motion depending on parallel guides and make the connected links rotate. A couple of links connected by sliders do coupling motion. The end-effector called a link tip has orientation angle. Through the kinematics analysis of this manipulator, we found displacement, velocity and acceleration using direct and inverse kinematics. We used equations that derived from this analysis and determined five constraint conditions. These conditions had much to do with rotation states of links, the relative relation of link length and coupling motion state. To verify those, we suggest a new algorithm regarding constraint conditions of a manipulator. With the result which performed the algorithm, we found out that operation range of coupled links was limited by relative relation of link length and that manipulator was not able to carry out a series of link motion, in case of being the link vertical between two parallel guides.