• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.11a
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• pp.86-93
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• 1989

이론적으로 진원의 저어널과 슬리브를 갖는 저어널베어링은 저어널과 슬리브가 등속으로 역회전할 경우 부하능력이 발생하지 않으므로 베어링으로서의 기능이 상실된다. 따라서, 저어널과 슬리브가 거의 등속으로 역회전하는 계에 대해서는 진원의 저어널베어링을 사용할 수 없고, 다른 종류의 베어링으로 지지하여야 할것이다. 역회전하는 저어널-베어링 계의 예로서는 터어보엔진의 인터샤프트베어링을 들 수 있다. Vance(1)는 고속 터어보엔진의 경우 공기역학적인 관점에서 가스제너레이터축과 파워터빈축이 서로 역회전하는 것이 바람직한 경우도 있는데, 이때 미끄름저어널베어링은 역회전시 부하능력의 감소로 인해 적용하기 어렵다고 하였다. 실제로 현재의 모든 인터샤프트 베어링으로서는 구름베어링이 사용되고 있다. 본 논문에서는 저어널과 슬리브가 역회전하는 프로팅링저어널베어링의 정특성을 해석하여 프로팅링저어널베어링이 역회전 저어널-베어링계를 충분히 지지할 수 있음을 이론적으로 밝히고자 한다. 윤활이론으로서는 층류상태에 대한 등온 유한장베어링이론을 사용하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1190-1193
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• 2004

The purpose of this study is to evaluate the possibility of identifying joint damping property through commercially available isokinetic ergometer (BIODEX). The proposed method is to estimate the damping torque of the knee joint from the difference between the external joint torque for maintaining isokinetic movement and the gravity torque of the lower leg. The damping torque was estimated at various joint angular velocities, from which the damping property would be derived. Measurement setup was composed of the BIODEX system with an external force sensor and Labview system. Matlab was used in the analysis of the damping property. The experimental result showed that the small variation in angular velocity due to acceleration and deceleration of the crank arm resulted in greater change of inertial torque than the damping torque, so that the estimation of damping property from the isokinetic movement is difficult.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.192-198
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• 2002

There are genuine parts, non-genuine parts and recycled parts which can be replaced for the repair of damaged parts of crashed cars. It is the recent trend in korea that recycled C. V joints are more popular than the genuine parts fur repairing crashed cars due to the cost. Performance of recycled C. V. joints as replacement parts was tested and analysed in this study. To examine the durability of the recycled parts, the replaced C. V joints after repair were tested and analysed periodically. The results were showed that basic performance of the recycled parts was normal. However ball cage was more frequently damaged than genuine parts. We concluded that a standard test for recycled parts is required to get a safe and durable parts.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2234-2244
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• 1994

A process sequence of multi-operation cold forging for actual application in industry is designed with the rigid-plastic finite element method to form a constant velocity joint housing(CVJ housing). The material flow during the CVJ housing forming is axisymmetric until the final forging process for forming of ball grooves. This study treats the deformation as an axisymmetric case. The main objective of the process sequence design is to obtain preforms which satisfy the design criteria of near-net-shape product requiring less machining after forming. The process sequence design also investigates velocity distributions, effective strain distributions and forging loads, which are useful information in the real process design.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.56-62
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• 2014

During the hot forging process, the most common cause of tool failure is wear. Tool wear results in the gradual loss of part tolerances, after which eventually the tool must be replaced or repaired. In order to maximize the lifetimes of forging tools, it is important to investigate the wear mechanisms of these tools. In this study, the hot forging of the outer race of an automotive constant-velocity joint was analyzed by a finite element method to investigate the wear distribution, especially the amount and location of the maximum expected wear damage, using Archard's wear model, which was modified considering the forging temperature. Forging analyses were carried out after modifying blocker forging tools based on established versions. The modified blocker tools resulted in an increase in the tool life up to 31% with a finisher punch.

• Tribology and Lubricants
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• v.29 no.4
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• pp.223-227
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• 2013

A GAF (generated axial force) is produced at a plunging-type CVJ (constant velocity joint). A high GAF can cause vibrations in a vehicle. Grease is used to reduce friction between the roller and the track of the outer case of a CVJ. The grease performance depends on the surface conditions and operating temperature. The surface of the outer case is extremely rough and hard. In recent times, the maximum operating temperature of CVJs has crossed $140^{\circ}C$, because the exhaust line is now located close to the CVJ. In this study, we examined the friction characteristics of friction additives at $25-150^{\circ}C$ and determined an optimal formulation with a low friction coefficient. This formulation can be used to develop low-friction grease that can reduce the GAF produced at a CVJ by approximately 7-26%.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.102.1-102.1
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• 2012

Ti 및 Ti 합금은 치과 및 정형외과 등의 분야에서 생체재료로써 다양한 용도로 적용되고 있으며, 보다 안전하고 우수한 특성의 Ti 합금 개발에 대한 관심이 높아지고 있다. 본 연구에서는 Ti-Nb-Ge 합금의 초탄성 특성에 미치는 집합조직의 영향에 대해 조사하였다. 집합조직 제어를 위해 등속 및 이주속 압연을 적용한 후 $850^{\circ}C$에서 30분~2시간까지 어닐링하였다. 광학현미경과 SEM-EBSD를 이용하여 미세조직 및 집합조직을 분석하고, 순환식 인장시험을 통해 시편의 초탄성 특성을 평가하였다. 등속압연 후 어닐링한 시료의 경우 alpha-fiber 집합조직이 발달하는 한편, 이속압연 후 어닐링한 시료는 {113}// 및 {331}의 집합조직이 발달하는 것으로 나타났다. 마르텐사이트 변태에 의한 변형회복능과 집합조직 성분별 강도의 관계를 비교한 결과, alpha-fiber 집합조직이 발달할수록 변형회복능이 증가하는 것으로 나타났다.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.121-133
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• 2008

We presented design methodology of constant velocity joint for passenger cars using design of experiment. On the basis of contact normal stress of internal components of constant velocity joints, we performed a sensitivity analysis of several design parameters. And then we performed robust design and optimization design process. As a result, we could find robust design and also propose the optimized design. Presented design process would be very helpful for engineers who are suffer for new constant velocity joint design.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.1
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• pp.1-8
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• 2005

Recently, swash plate type hydraulic axial piston motors/pumps are being extensively used in the world, because of simple design, light weight and effective cost. Structural problem of the swash plate type motor/pump is that tilting angle of swash plate should be limited to relatively small value and lateral farce on pistons has an undesirable effect in reciprocating motion. To solve these problems, piston rod mechanism, which is commonly used in bent axis type motor/pump, is considered to be applied to the swash plate type motor/pump. In this paper, kinematic analysis was done on the piston rod mechanism. A series of formula were derived and numerical calculations were done for a set of motor parameters.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1477-1485
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• 2003

The displacement vector field can be represented in terms of a scalar potential ${\phi}$ and a vector potential ${\phi}$. The scalar potential ${\phi}$ is related to dilatational waves and the vector potential ${\phi}$ is related to rotational waves. Using these two complex displacement potentials, the stress and displacement fields for steadily growing interface cracks in dissimilar materials are obtained. The energy release rate for steadily growing interface cracks in dissimilar materials are also obtained. And with photoelastic isochromatic patterns simulated by computer graphics, the stress intensity factors are discussed.