• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.682-687
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• 2011

Calibration mirror mechanism has been widely used for on-board calibration with black body. The calibration mirror is deployed to reflect the radiation energy from the black body to the image sensor for calibrating the sensor system. After the calibration, the calibration mirror is stowed not to hide a main optical path. It also has a fail-safe function which can stow the mirror by just removing the input power of motor when the calibration mirror is stopped at certain position during the calibration. In the present work, the operation concept, design, torque analysis and functional test results of the calibration mirror mechanism with the aforementioned function have been introduced and investigated.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.311-319
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• 2017

The primary suspension system of a railway vehicle restrains the wheelset and the bogie, which greatly affects the dynamic characteristics of the vehicle depending on the stiffness in each direction. In order to improve the dynamic characteristics, different stiffness in each direction is required. However, designing different stiffness in each direction is difficult in the case of a general suspension device. To address this, in this paper, an optimization technique is applied to design different stiffness in each direction by using a conical rubber spring. The optimization is performed by using target and analysis RMS values. Lastly, the final model is proposed by complementing the shape of the weak part of the model. An actual model is developed and the reliability of the optimization model is proved on the basis of a deviation average of about 7.7% compared to the target stiffness through a static load test. In addition, the stiffness value is applied to a multibody dynamics model to analyze the stability and curve performance. The critical speed of the improved model was 190km/h, which was faster than the maximum speed of 110km/h. In addition, the steering performance is improved by 34% compared with the conventional model.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.36-42
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• 2010

In this study, the deformation and stress are analyzed through modal and harmonic response analysis at resonance on leaf spring. The displacement range of 7 to 14 mm is shown at natural frequencies as 6 kinds of resonance modes. The maximum deformation is shown as 8.8781mm at Mode 2. The maximum displacement and stress at leaf spring are shown as 0.0458 mm and 72.533 MPa respectively on 1200 Hz. The comfortability of passenger becomes better on leaf spring at suspension system by use of this design model.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.4
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• pp.67-72
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• 2010

In this study, performance analysis and design optimization is carried out for a multi-rate spring brake system, which is used in a cable ride to stop the arriving passengers in safe and comfortable manner. Mathematical model for the spring is developed toward the objective of minimizing the impact at the arrival while satisfying the constraint of limited distance at the stop. Matlab code is utilized to examine parameters affecting the performance of the brake system. The results are validated by a commercial software RecurDyn. Kriging meta model is used to reduce the computational cost of the analysis. Optimization is conducted by RecurDyn, from which the design parameters are determined that minimizes the impact at the stop.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.773-778
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• 2009

Chevron rubber springs are used in primary suspensions for rail vehicle. Chevron rubber spring have function which reduce vibration and noise, support load carried in operation of rail vehicle. Prediction and evaluation of characteristics are very important in design procedure to assure the safety and reliability of the rubber spring. The computer simulation using the nonlinear finite element analysis program executed to predict and evaluate the load capacity and stiffness for the chevron spring. The non-linear properties of rubber which are described as strain energy functions are important parameters. These are determined by material tests which are uniaxial tension, equi-biaxial tension and shear test. The appropriate shape and material properties are proposed to adjust the required characteristics of rubber springs in the three modes of flexibility.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.148-155
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• 2014

Most truck fires breaking out on the expressway are directly damaged by fire destruction of truck and freight and many of them cause indirect damage such as serious traffic holdups. This study analyzed the fire causes and their liability of the 25-ton truck fire breaking out during expressway driving. This truck fire was caused by manufacturing defect of return spring of a braking system. The fire liability rested with a maker(manufacturer) rather than a truck owner or a driver and the maker also bore fire liability based on the Product Liability Law.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.5
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• pp.98-105
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• 1998

In the automotive suspension system, especially, Mcpherson strut type, if the resultant of the force through tire and the link reaction force is not coincident with the spring force, the side load against shock-absorber occur. The magnitude of side load is proportional to the difference between resultant force and spring force. To reduce side load, several method can be used, and one is to use the side load coil spring. This study summarize the development results of side load coil spring, i.e., how to design, analysis, manufacture, and test.

• 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.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.102-107
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• 2004

Suspension part should have enough endurance during its lifetime to protect passenger. Therefore, the coil spring is one of the major suspension part of an automobile. Corrosion fatigue strength of the coil spring depends on many factors including mechanical and environmental properties. In this paper, residual stresses by shot peening was analyzed using finite element analysis and evaluated its effect on corrosion fatigue strength.

• The Safety technology
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• no.175
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• pp.15-17
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• 2012

한 대의 자동차가 완성되기 위해서는 약 2~3만 개에 가까운 부품이 들어간다. 자동차의 심장인 엔진부분은 물론 자동차의 외형을 이루는 몸체, 각종 전기장치 등을 만들기 위해서 갖가지 부속품이 필요한 것이다. 이들 부품 가운데 특히 많이 쓰이는 것이 압축코일, 비틀림코일, 태엽 등의 각종 스프링이다. 이와 같은 스프링을 제작하는 기업은 많지만 그중에서도 (주)디지에쓰는 업계에서 명성이 자자하다. 지난 1974년 설립돼 현재 40여 명이 근무하고 있는 작은 회사이지만 기술연구소를 설치 운영하고 있을 정도로 연구개발에 힘써 온 결과 남부럽지 않은 기술력을 갖게 됐기 때문이다. 2010년에 중소기업청으로부터 기술혁신형 중소기업으로 선정된 것이 이를 입증하고 있다. 작지만 강한 기업이라는 수식어가 전혀 어색하지 않은 것이다. (주)디지에쓰가 명성을 얻고 있는 데에는 또 다른 이유가 있다. 바로 철저한 안전관리를 바탕으로 5년 연속 무재해를 이어가고 있기 때문이다. 우리나라의 산업재해 가운데 80% 이상이 50인 미만 소규모 사업장에서 발생하고 있다는 점에 비춰보면 이곳의 무재해 기록이 갖는 의미는 남다르다고 할 수 있다. 철저한 안전관리를 바탕으로 성장을 거듭하고 있는 (주)디지에쓰를 찾아가 봤다.