• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.354-359
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• 2012

Improvement of structure-borne noises in the vehicle compartments has been one of the primary concerns in the development of vehicles. The booming is an annoying low frequency interior noise and vibration in vehicle. But it is difficult to reduce the structure-born booming noise in traditional method - trial and error within the shorten development schedule. So in present, the structure dynamic modification (SDM) method helpful to predict the effect of the local mass, stiffness, and damping is introduced. So in order to reduce the interior booming noise, the SDM was performed, and verified with modal test result. It was shown that the interior booming noise was reduced as predicted.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.571-575
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• 2008

An engine cradle is a quite important structural assembly for supporting the engine, suspension and steering parts of vehicle and absorbing the vibrations during the drive and the shock in the car crash. Recently, the engine cradle having structural stiffness enough to support the surrounding parts and absorbing the shock of collision has been widely used. The hydroforming technology may cause many advantages to automotive applications in terms of better structural integrity of parts, reduction of production cost, weight reduction, material saving, reduction in the number of joining processes and improvement of reliability. We focus on increasing the durability and the dynamic performance of engine cradle. For realizing this objective, several optimization design techniques such as shape, size, and topology optimization are performed. This optimization scheme based on the sensitivity can provide distinguished performance improvement in using hydroforming.

• 소음진동
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• 제5권1호
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• pp.29-35
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• 1995

This paper presents the simultaneous optimal design of structure and LQG control systems for the improvement of riding comforts of active vehicle suspension systems. The performance index of riding comforts is extended to include frequency-weighted acceleration in the quadratic cost functional. Janeway human response curve with respect to acceleration is used to verify the usefulness of the presented method. The method is applied to a half model of an active vehicle suspension systems with elastic body moving on randomly profiled road. The values of stiffness of suspensions are used for the structural design variables. The conjugate gradient method is used for optimization. The simulated results of simultaneous optimization with frequency-weighted cost functional are compared with those without frequency- weighted cost functional.

• 한국자동차공학회논문집
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• 제10권6호
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• pp.202-208
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• 2002

Ball k nut type steering gear box has disadvantages on on-center range as compared with rack & pinion type because of many linkages. In this study, a technique which can improve the on-center loose feel is introduced. The improvement can be obtained by putting simple devices on steering gear box valve body which can change the stiffness of steering gear on on-center handling range. Analysis and test of the vehicle with improved steering system are performed.

• Advanced Composite Materials
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• 제18권3호
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• pp.251-264
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• 2009

Nonlinear mechanical behaviors of unidirectional carbon fiber-reinforced plastic (CFRP) laminates using cup-stacked carbon nanotubes (CSCNTs) dispersed epoxy are evaluated and compared with those of CFRP laminates without CSCNTs. Off-axis compression tests are performed to obtain the stress-strain relations. One-parameter plasticity model is applied to characterize the nonlinear response of unidirectional laminates, and nonlinear behaviors of laminates with and without CSCNTs are compared. Clear improvement in stiffness of off-axis specimens by using CSCNTs is demonstrated, which is considered to contribute the enhancement of the longitudinal compressive strength of unidirectional laminates and compressive strength of multidirectional laminates. Finally, longitudinal compressive strengths are predicted based on a kink band model including the nonlinear responses in order to demonstrate the improvement in longitudinal strength of CFRP by dispersing CSCNTs.

• 품질경영학회지
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• 제46권2호
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• pp.269-282
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• 2018

Purpose: The purpose of this study was to improve the FRP Van's durability by analyzing the problematic parameters, redesigning the rear van, and verifying the design drafts using the CAE analysis & Rig test. Methods: The collected data through the government quality inspection and field spot check were thoroughly analyzed through the characteristics diagram and the improvement suggestions were verified by performing CAE analysis, like the dynamic stiffness, Torsional stiffness, open/close condition's strength, Full car durability and Carrying out the actual test. Results: The results of this study are as follows; The output of CAE analysis shows that improvement suggestions have considerable effects on the reinforcement of FRP structure, and the actual torsion and open/close condition durability test prove that rear van may have durable life which is equivalent to vehicle life cycle. Conclusion: The structural weakness of KLTV's FRP rear van was overcome by applying the stiffener in rear van and changing the bonding method of each FRP pieces. That suggestions were proved using CAE analysis and Rig test.

• 한국도로학회논문집
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• 제11권4호
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• pp.9-15
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• 2009

본 연구는 도로안전 시설물의 풍하중에 의한 손상발생 사례를 토대로 현행 도로안전 시설물의 구조적 휨 성능을 평가하고 이에 대한 부재별 휨 성능개선을 위한 연구이다. 본 연구의 대상구조물로는 대표적인 도로안전시설물이며 풍하중에 대한 선행 피해사례가 밝혀진 방음벽 지주프레임을 대상으로 고려하였으며 이들 지주프레임의 휨 구조성능 및 형상설계에 대한 평가를 우선적으로 수행하였다. 본 연구평가 결과에서 나타난 현행 보강재의 구조적 성능을 토대로 중량 대비 구조적 강성이 우수한 유리섬유 강화플라스틱 (GFRP)을 활용하여 다양한 보강 형태에 따른 성능개선방법을 해석 및 실험적 연구를 통하여 수행하였다. 그 결과 효율적 성능개선을 위한 GFRP 적용방법의 경우 구조적, 시공적 측면에서 효율적인 것으로 평가되었고 자체적인 형상단면 최적설계를 통한 개선방법도 성능보강에 효과적인 것으로 해석적으로 평가되었다. 본 연구에서 적용된 GFRP 단면보강 및 최적형상설계 연구는 향후 노후 도로안전 시설물의 풍하중 또는 태풍으로 인한 피해예방을 위한 기초자료로서 효율적으로 활용될 수 있을 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제13권5호
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• pp.393-399
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• 2003

Hydraulic mounts show strong1y frequency-dependent stiffness and damping characteristics in low frequency range, which result from so called inertia track dynamics. A lumped mass has been incorporated in several mechanical models of the literature to take the inertia effect of the fluid in the track into consideration. Although complex s%illness by the mechanical model showed good agreements with the measured values, there exists a critical pitfall. In this paper, the shortcomings of mechanical models with lumped mass for hydraulic founts are clearly identified by illustrating actual measurements of the stiffness parameters for a hydraulic mount. It is conclusively discussed that the inertia effect of the fluid flow through the circular track is significant but latent. As an alternative to the mechanical model, a hydraulic model is claimed to be used for further dynamic analysis of engine/mount system or whole car system.

• 한국소음진동공학회논문집
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• 제25권4호
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• pp.247-254
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• 2015

Ride comfort is one of the major factors in evaluating the performance of the vehicle. Tire is closely related to the ride comfort of the vehicle as the only parts in contact with the road surface directly. Vertical stiffness which is one of the parameters to evaluate the tire performance is great influence on the ride comfort. In general, the lower the vertical stiffness, the ride comfort is improved. Research for improving the ride comfort has been mainly carried out by optimizing the shape of the pneumatic tire. However, demand for safety of the vehicle has been increased recently such as a run-flat tire which is effective in safety improvement. But a run-flat tire have trouble in practical use because of poor ride comfort than general tire. Therefore, In this paper, the research was carried out for improving the ride comfort through the optimization of the SIR shape inside a run-flat tire. Meta-model was generated by using the design of experiment and it was able to reduce the time for the finite element analysis of optimization. In addition, Shape optimization for improving the ride comfort was performed by using the genetic algorithm which is one of the global optimization techniques.

• 한국소음진동공학회논문집
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• 제25권3호
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• pp.169-175
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• 2015

This study aims to improve the dynamic stiffness of an inspection robot frame to prevent derailment from transmission lines. Finite element models for the transmission lines and robot frame are developed for the multi-body dynamic simulation. Natural frequency analysis was conducted using the FE models. Three types of spacer damper clamps installed on 4-conductor transmission lines are used to evaluate the derailment of the robot. Multi-body dynamic simulations with FE models are demonstrated for sub-span oscillation. When the robot operates, derailment of inspection robot from the transmission lines is determined because of resonance. To prevent the resonance, body position was changed and thickness optimization was conducted. The results show that derailment was not occurred because of the natural frequency improvement.