• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.83-88
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• 2015

Agricultural tractors are utilized on rough road such as rice paddy field. Therefore, static and dynamic load should be considered when simulating structural analysis with finite element analysis (FEA). But it consumes a lot of time and effort to measure dynamic load because of difficulty and complexity in modeling various field working load conditions and kinematics of machinery. In this paper, to reduce the efforts, 4-post road simulator is developed for agricultural tractor like modeling commercial vehicle. In proving ground test in our facility, I measured acceleration of front/rare axle and strain of body frame to validate input loads. The acceleration is used for defining input loads. And strain is validated with dynamics analysis including mode superposition method. As a result, I was able to calculate 4-post input road profiles, which represent similar proving ground profile with good reliability.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.125-132
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• 2011

The dynamic characteristics of valve train are responsible for the dynamic performances of engine. We derived the equation of motion for 6 degrees of freedom model of the valve train. Computer model is also developed with flexible multibody model considering contact between components. The simulation results with these two models are compared with experimental results. We investigated the effect of the two spring models, TSDA (Translational Spring Damper Actuator) element and flexible body model, on the valve behavior and spring force. It is found that the dynamic behavior of the two models are not very different at normal operational velocity of the engine. By modeling contact between cam and tappet, the stress distributions of the cam were found. Using stress distribution obtained, contact width and contact stresses of the cam surface were calculated with Hertz contact theory.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1718-1723
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• 2003

This paper presents a computational method for deformation modes of a flexible body in multibody system from the experimental modal analysis and an efficient method for flexible multibody dynamic analysis by use of the modes. It is difficult to directly use experimental modal parameters in flexible multibody dynamic analysis. The major reasons are that there are many inconsistencies between experimental and analytical modal data and experimental noises are inherent in the experimental data. So two methods, such as, a method for ortho-normalization of experimental modes and the other one for mode expansion, are suggested to gain deformation modes of a flexible body from the experimental modal parameters. Using the virtual work principle, the equation of motion of a flexible body is derived. The effectiveness of the proposed method will be verified in the numerical example of cab vibration of a truck by comparing analysis and test results.

• The monthly packaging world
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• s.262
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• pp.94-104
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• 2015

환경부는 '화학물질의 등록 및 평가 등에 관한 법률(화평법)'과 '화학물질관리법(화관법)' 시행규칙을 공포하고 지난 달부터 시행했다. 환경부에 따르면 두 법안은 화학물질의 체계적인 관리로 사전에 안전사고를 예방하고 국민건강과 환경을 보호하기 위해 제정됐다. 화학물질의 생산 유통 등 모든 과정의 안전관리를 강화하는 것이 골자다. 우선 화평법 시행에 따라 모든 신규 화학물질과 연간 1톤 이상 제조 수입되는 기존 화학물질에 대한 등록이 의무화되고 등록 신청 기준도 강화된다. 다만 제조 수입량이 연간 1톤 미만일 경우 등록 신청 제출 자료를 정식 등록 9개보다 적은 4개로 간소화하고 등록기간도 30일에서 3~7일로 줄였다. 또 유해물질 함유제품으로 인한 피해를 예방하기 위해 생활화학 제품 15종을 우려제품으로 지정해 안전 표시기준을 준수하도록 했다. 관리대상 품목은 세정제 합성세제 표백제 섬유유연제 코팅제 접착제 방향제 탈취제 방청제(금속부식 방지제) 김서림방지제 물체염탈색체 문신용염료 소독제 방충제 방부제 등이다. 화관법에서는 유해 화학물질 취급 때 공통 적용되는 46개 준수사항을 규정하고 물질별로 구체적인 취급기준을 고시하도록 했다. 취급시설의 설치 관리기준도 시설 종류별로 구체화했다. 새로 도입되는 장외 영향평가는 취급시설 설치자가 화학사고 발생 시 사업장 주변지역 사람이나 환경에 미치는 영향을 사전에 평가해 시설을 안전하게 설계 설치하도록 규정했다. 과징금과 행정처분 기준도 구체화했다. 행정처분은 2년 내 위반 횟수에 따라 경고 개선명령 영업정지 허가취소로 차등화하고 사고가 일어나면 사상자와 사업장 밖 피해액을 기준에 따라 산정해야 한다. 본 고에서는 두 법률의 주요 내용과 함께 주요 문의 사항을 살펴봄으로써 이해를 도우고자 했다.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.5
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• pp.491-496
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• 2015

Electric handbike can be easily detachable to various sizes of manual wheelchair and the elderly and people with disabilities can use them easily. Therefore, connectors used for coupling between the handbike and manual wheelchair must secure structural stability for occupant safety. However, related research is rare. The aim of this study is to find the connector with highly structural stability by comparing static and dynamic mechanical characteristics among three typical connectors(a snatch lock, a slide latch, and a fastener) by computational simulations. To perform static and dynamic simulation, we referred to durability test based on Korean Standards and then calculated mechanical stresses in connectors. The results showed that the snatch lock addressed the lowest von-mises stress under the same mechanical condition. Therefore when using the combination of a handbike and a wheelchair, we concluded that the snatch lock is considered as the structurally stable connector to structural stability and usability.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.915-921
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• 2013

Most of large scale solar panel handling robots adopt the timing-belt drive system for its driveline because of the simplicity and the easiness of implementation. The vibration caused by the flexure of the timing belt would increase as the size and the weight of the panel that the robot handles increase and the vibration would deteriorate the precision and/or productivity of the whole robot system. For the development of a proper control system and for the improvement of the design of the robot it is important to estimate the oscillatory response of the robot system including the flexible drive system properly. In this paper a flexible multi-body dynamics model of a large-scale solar-panel-handling robot with the flexible timing-belt drive system is developed using a generic multi-body dynamics analysis program, RecurDyn.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.165-175
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• 2000

In recent years, it becomes a very important issue to consider the mechanical systems such as high-speed vehicles and railway trains moving on elastic beam structures. In this paper, a general approach, which can predict the dynamic behavior of constrained mechanical system and elastic beam structure, is proposed. Also, various supporting conditions of a foundation support are considered for the elastic beam structures. The elastic structure is assumed to be a nonuniform and linear Bernoulli-Euler beam with proportional damping effect. Combined Differential-Algebraic Equations of motion are derived using multibody dynamics theory and Finite Element Method. The proposed equations of motion can be solved numerically using generalizd coordinate partitioning method and Predictor-Corrector algorithm, which is an implicit multi-step integration method.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.687-696
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• 2019

To identify the driving dynamic characteristics of the Tractor-Trailer Type Transporter for mounting a large scale precision equipment, real vehicle driving tests on the 3 inch-bump-space-road were performed. And using general Dynamics Analysis Program - RecurDyn(V8R5), Dynamics M&S were carried out assuming the similar condition with real tests. Then the acceleration data obtained from real tests and M&S were analyzed and compared with each other in the part of root-mean-square-acceleration($g_{rms}$), peak-acceleration($g_{peak}$) and frequencies. In simple view of the $g_{rms}$ & $g_{peak}$, although the results of MRBD are more similar to ones of the real vehicle driving tests, but the results of RFlex have more information to get various useful dynamic characteristics.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.2
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• pp.196-209
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• 2022

Driving dynamic characteristics of semi-trailer loaded with precise equipments are very important to protect them from vibration, impact or other disturbances. In this paper, in order to identify the driving dynamic characteristics of the large scale semi-trailer equipped with swivel axle and hydropneumatic suspension unit, Dynamics Modeling & Simulation(M&S) were performed using general Dynamics Analysis Program(RecurDyn V9R2). The semi-trailer was modeled as two types - one is Multi Rigid Body Dynamics(MRBD) model, and the other Rigid-Flexible Body Dynamics(RFlex) one. The natural vibration mode and frequencies of semi-trailer body, acceleration of dummy-weight, pitch, roll and yaw of dummy-weight, swivel axle and hydropneumatic suspension cylinder support structure, and acting force of hydropneumatic suspensions etc. were obtained from the M&S. Additionally frequency analysis were performed using the data of behavior obtained from above M&S. Generally the quantitative results of RFlex are larger than them of MRBD in view of magnitude of the comparable parametric values.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.874-880
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• 2003

Many mechanical systems are over-constrained if only rigid bodies are used to model the system. One example of such system is a satellite system with solar panels. To avoid this over-constrained problem, solar panels can be modeled as flexible bodies. The CMS(Component Mode Synthesis) method is widely used to analyze the flexible multi-body system because it can considerably approximate the deformation of the flexible bodies using small number of well-selected mode. However, it is very difficult to decide the boundary condition and the selection of modes. In this paper, the methods for mode synthesis and setting the boundary condition are presented to analyze the flexible multi-body system with over-constraints. Finally, the reliability of proposed method is verified by solar panel's deployment test.