• Journal of Industrial Technology
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• v.20 no.B
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• pp.105-113
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• 2000

Air springs are now widely used in bus or truck suspensions due to their advantages over conventional metal spring as coil or leaf springs. Air springs have soft spring rates, which give better ride quality, and additional leveling system provides constant ride height and maintains almost same vertical natural frequencies. A mathematical model of an air spring suspension system with height control system is constructed and dynamic responses of the suspension system are investigated in the light of leveling valve motion characteristic, vertical motion natural frequency. Also, using a full vehicle model, handling characteristics of an air spring suspension is studied and the results are compared with real test results, which shows good agreements.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.65-70
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• 2007

The LNG tank are properly designed to fit with the limited installation space of a light duty truck, Hyundai Porter II. This designed LNG tank has 36 liter capacity, so two LNG tanks installed on Porter II truck allow it to run about 432 km per fueling. It is almost two times greater than CNG mileage for same truck. To analyze the relationship between car acceleration and heat leak for different fuel vapor/liquid ratios, the modified Fortran program "Pro-Heatleak" is used. Computational analysis shows that the relationship between the heat leak and vapor/liquid ratio is linearly inversed. Heat leak increases with increasing of car acceleration when fuel vapor/liquid ratio is less than 0.5 and decreases when fuel vapor/liquid ratio is greater than 0.5. The difference between maximum and minimum heat leak for full tank is about 12 percents. For the fuel vapor/liquid ratio equal to 0.5 heat leak does not depend on car acceleration.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.104-111
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• 2003

The performance of shock absorber is directly related to the car behaviour and performance, both for handling and comfort. In this study, a mathematical nonlinear dynamic model and computational method are introduced to study the flow and performance of shock absorber. The flow characteristics of components(piston and body valve) are investigated and applied to dynamic modeling of shock absorber to predict the damping force. The simulation results agree with the test data well. The shock absorber model proposed in this paper is applicable as a part of a full vehicle suspension simulation.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.319-320
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• 2015

A hybrid converter for the on-board charger consisting of a soft switching full bridge (SSFB) and a half bridge (HB) LLC resonant converter is proposed. The proposed topology adopts an additional switch and a diode at the secondary side of SSFB converter to guarantee the wide ZVS range of primary side switches and to eliminate the circulating current. The output voltage is regulated by controlling the duty cycle of secondary side switch. The effectiveness of the proposed converter was experimentally verified using a 10-kW prototype circuit. The experimental results show 96.8% peak efficiency.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.68-74
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• 1998

The ESPI(Electronic Speckle Pattern Interferometry) is a real time, full-field, non-destructive optical measurement technique that allows static and dynamic deformation analysis and surface shape measurements of engineering structures. e .g. turbine blades. vehicle engine components, body panels, etc. This technique is very similar to holographic interferometry, but uses a solid static camera and an image processing board for recording and digital processing of speckle patterns. In this paper it is presented that FEM results for the free vibration of symmetrically laminated composite as [30/-30/90]s. The natural frequencies of laminated composite rectangular plates having the particular boundary condition are experimentally obtained. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with calculation by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1083-1088
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• 2001

To predict vibrational energy density and intensity of complex structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for the plate, beam and some coupled structural elements are developed at present. The vibration energy density and intensity of foreign vehicle is predicted successfully with FE full model of 60,000 DOF using the developed PFFEM program.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.127-137
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• 2009

Hypoid gears are widely used in rear drive and 4WD vehicle axles. Investigation of their sensitivity to deflections is one of the most important aspects of their design and optimization procedures. The deflection test is performed in the actual gear mounting using completely processed gear. This test should cover the full operating range of gear loads from no load to peak load. Under peak load the contact pattern should extend to the tooth boundaries without showing a concentration of the contact pattern at any point on the tooth surface. Transmission error is tested on an axle assembly triaxial real car load condition.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.854-859
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• 1994

As powertrain noise is better and better controlled, road noise inputs become more important. The interior road noise of a car is mainly induced by the wheels rolling over the road surface. Each of the four wheels act as an independent and uncorrelated excitation input. To rank the energy transfer form each input to the interior, a Transfer Path Analysis (TPA) needs to be made-which requires operational vibration measurements. However due to the multiple uncorrelated inputs, phase relations vary continuously. It is therefore necessary to separate the operational data into set of "independent phenomena" by means of a Principal Component Analysis (PCA). A TPA can then be carried out for each independent phenomenon. Operational deflection shapes referenced to these principal components share the physical phenomena. The details of the methodology are discussed and a discussion of the results on a car shows that the method gives accurate results for full vehicle testing.e testing.

• Journal of Drive and Control
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• v.10 no.4
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• pp.7-13
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• 2013

A tractor is a farm vehicle that is designed to provide a high tractive effort at low speed. It is used for versatile agricultural tasks such as hauling a trailer, tillage, mowing and construction work. As the intensity of work increases, tractors equipped with automatic transmission become popular due to the work convenience. Though manual and power shuttle transmissions are produced by domestic corporations, development for full-automatic power shift transmissions has never been challenged, and so related technology level is quite low. This paper gives a survey of the automatic transmissions from advanced foreign company, which includes layout of gear train, the way hydraulics controls clutches and brakes, electronic control system. The results are expected to be utilized as a basis in the development of original power train design for tractor.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.17-19
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• 2019

본 논문에서는 전기자동차(EV) 충전기용 위상천이 풀브리지(PSFB) 컨버터의 정류기 다이오드 전압 스트레스를 저감하기 위한 새로운 형태의 클램핑 회로를 제안한다. 제안하는 회로는 하나의 커패시터로 구성된 매우 단순한 구조임에도 불구하고, 정류기 다이오드의 전압 스트레스를 큰 폭으로 감소시킨다. 뿐만 아니라, 해당 회로는 프리휠링 구간의 전류를 감소시키며, 출력 인덕터의 사이즈 또한 줄일 수 있다는 장점을 지닌다. 따라서 제안된 컨버터는 정류기 다이오드의 도통손실을 큰 폭으로 저감하여 고효율을 달성할 수 있으며, 간단한 구조의 클램핑 회로와 줄어든 출력 필터 사이즈에 의해서 고밀도화를 달성할 수 있다. 제안된 컨버터의 타당성은 3.3kW, $270-420V_{DC}$의 CC-CV 모드 충전 조건하에서 실험하여 검증되었다.