• 한국군사과학기술학회지
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• 제23권5호
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• pp.502-515
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• 2020

To identify the dynamic characteristics of the Auto-leveling system applied to the Tractor-Trailer type Transporter for mounting a large scale precision equipment, Dynamics Modeling & Simulation were performed using general Dynamics Analysis Program - RecurDyn(V9R2). The axial load data, transverse load data and pad trace data of leveling actuators were obtained from M&S. And they were analyzed and compared with each other by parameters, i.e. friction coefficients on the ground, landing ram speed of actuators, and direction & quantity of ground slope. It was observed that ground contact friction coefficients affected to transverse load and pad trace; the landing ram speed of actuators to both amplitude of axial & transverse load, and this phenomena was able to explain from the frequency analysis of the axial load data; the direction of ground slope to driving sequence of landing ram of actuators. But the dynamic behaviors on the two-directional slope were very different from them on the one-directional slope and more complex.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.121-128
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• 2005

In most researches on the ride comfort analysis of passenger vehicles, the flexibility of the vehicle body has been not considered as an important factor, because the resonance frequencies of the vehicle body related to pitching, yawing and rolling motions are below 10Hz while the resonance frequencies of the vehicle body related to the flexibility are above 20Hz approximately. Nevertheless, the paper shows that the consideration of the local flexibility (or local stiffness) of the 4 corners on which shock absorbers are mounted influences the ride comfort. A simple beam model is devised to qualitatively examine the effect of the change of the local stiffness of the vehicle body on the ride comfort. Based on the results obtained from the analysis of the one-dimensional model, multi-body dynamic analysis considering the flexibility of the vehicle body is performed using ADAMS and MSC/NASTRAN. Natural frequencies and mode shapes computed by MSC/NASTRAN are used as input data for multi-body dynamic analysis in ADAMS. Through simulations using ADAMS, it has been found that the ride comfort can be improved by changing the local stiffness of the vehicle body and that the simulation results agree with experiment results.

• 항공우주시스템공학회지
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• 제12권1호
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• pp.17-26
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• 2018

다물체 동역학 기법을 이용하여 가변속 제어모멘트자이로와 인공위성의 상호작용하는 모델을 개발한 연구결과를 소개한다. 이 상호작용 모델을 이용하여, VCMG 모터의 사양 설계와 위성 구조물의 강도설계에 활용할 수 있는 데이터를 얻었다. 그리고 태양 전지판과 같은 유연 모듈의 상호작용 효과도 포함하였다. 위성의 기동에 의하여 유연 모드가 야기되고, 이 모드의 진동에 의하여 위성 자세에 변동이 가해진다. 모델리카 언어로 시뮬레이션 프로그램을 개발하고, 제시한 모델의 타당성을 검증하였다.

• 한국전산구조공학회논문집
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• 제27권5호
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• pp.379-384
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• 2014

본 논문은 갠트리 크레인의 설계를 위해 컨테이너 하역작업 시 특정하중 조건하의 RTGC(Rubber Tired Gantry Crane)의 동적거동과 그에 따른 윤하중을 분석한 내용을 기술하고 있다. 먼저 RTGC의 동적거동을 살펴보기 위해 거대 구조물인 크레인의 유한요소 모델을 개발하고 고유진동수와 고유모드의 모달시험결과를 이용하여 유한요소모델을 검증하였다. RTGC의 기타 부속품은 3차원 CAD모델링을 통해 다물체 동역학해석 소프트웨어인 ADAMS에서 강체로 모델링하였다. 본 연구에서 하중 조건은 일반적인 컨테이너의 이송조건(OP1)과 외부부하조건 없이 단순히 트롤리를 이용하여 컨테이너를 하역하는 2가지 경우로 고려하였다. 해석 결과 RTGC의 컨테이너 작업 시 발생하는 크레인의 진동은 거대 구조물의 강성과 변형에 주로 기인함을 확인하였으며 이러한 크레인의 진동은 RTGC의 움직임을 발생시켜 컨테이너 하역작업 불능 등의 거동을 발생시킬 수 있음을 분석할 수 있었다.

• 항공우주시스템공학회지
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• 제13권5호
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• pp.94-101
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• 2019

복합재료 반사판 안테나의 전개 특성을 해석 모델을 통하여 살펴보고 실험을 통하여 검증하고자 한다. 두 개의 회전 자유도를 가지며 스프링의 탄성 에너지에 의해 작동되는, 전개 메커니즘을 기반으로 반사판 안테나의 동역학적 해석 모델을 수립하였다. 유연 다물체 동역학 해석 프로그램인 ADAMS를 이용하여 패널의 전개 속도, 구조 변형 그리고 충격력을 분석하였다. 중력보상 장치를 이용하여 탄소섬유 강화 플라스틱(CFRP)으로 제작된 안테나 패널의 전개거동 특성을 실험적으로 검증/분석하였다. 안테나 패널이 전개되는 동안 발생하는 충격 응답 및 진동 문제를 확인하고, 댐퍼를 이용하여 안정적으로 전개가 됨을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.641-646
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• 2008

Long and slender body with or without flexible supports under severe operating condition can be unstabilized even by the small cross flow. Turbulent flow mixer, which actually increases thermal-hydraulic performance of the nuclear fuel by boosting turbulence, disturbs the flow field around the fuel rod and affects dynamic behavior of the nuclear fuel rods. Few studies on this problem can be found in the literature because these effects depend on the specific natures of the support and the design of the system. This work shows how the dynamics of a multi-span fuel rod can be affected by the turbulent flow, which is discretely activated by a flow mixer. By solving a state-space form of the eigenvalue equation for a multi-span fuel rod system, the critical velocity at which a fuel rod becomes unstable was established. Based on the simulation results, we evaluated how stability of a multi-spanned nuclear fuel rod with mixing vanes can be affected by the coolant flow in an operating reactor core.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.1-7
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• 2010

The paper proposes a multi-body dynamic simulation to numerically evaluate the generated axial force(G.A.F) and plunging resistant force(P.R.F) practically related to the shudder and idling vibration of an automobile. A numerical analysis of two plunging types of CV joints, tripod joint(TJ) and very low axial tripod joint(VTJ), is conducted using the commercial program DAFUL. User-defined subroutines of a friction model illustrating the contacted parts of the outboard and inboard joint are subsequently developed to overcome the numerical instability and improve the solution performance. The Coulomb friction effect is applied to describe the contact models of the lubricated parts in the rolling and sliding mechanisms. The numerical results, in accordance with the joint articulation angle variation, are validated with experimentation. The offset between spider and tulip housing is demonstrated to be the critical role in producing the 3rd order component of the axial force that potentially causes the noise and vibration in vehicle. The VTJ shows an excellent behavior for the shudder when compared with TJ. In addition, a flexible nonlinear contact analysis coupled with rigid multi-body dynamics is also performed to show the dynamic strength characteristics of the rollers, housing, and spider.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.844-849
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• 2008

A nano-imprinting stage has been widely used in various fields of nano-technology. In this study, A 4-axis nano-imprinting stage is modeled with using the 3D-CAD Tool. Structural components such as an upper-plate, bearings and cross-roller-guides are modeled with finite elements to analyze flexibility effect during the precision stage motion. In addition, Dynamic analysis is executed to reproduce actual motion of 4-axis nano imprinting stage.

• 대한기계학회논문집 C: 기술과 교육
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• 제5권2호
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• pp.89-95
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• 2017

제품을 개발하는데 있어서 경량화와 원가절감이라는 두가지 요소는 가장 중요한 화두이다. 특히 대형 LCD 로봇은 최대 $3{\times}3m$ 이상의 글라스를 7m 높이까지 상하, 전후로의 직선운동과 선회축을 중심으로한 회전운동을 하면서 작업공정간 이송을 가능케 하는 대형 구조물이다. 따라서 지나치게 무거울 경우에는 클린룸내 설치에 문제가 있을 수 있고 반송물의 정확한 이송을 위하여는 고강성이 요구되며 대량 생산을 위한 연속작업을 충분히 감당할 수 있는 내구강도를 확보하여야 한다. 따라서 경량화, 고강성, 고강도 제품에 대한 요구는 갈수록 증가하고 있다. 현재 개발되고 있는 11 세대 대형 LCD 승강프레임은 이러한 요구조건을 충족하기 위하여 최적설계 기법을 적용하여 기존 제품 대비 경량화와 고강성 요구조건을 만족하였으며 용접부에 대한 상세 수명평가로 내구강도에 대한 신뢰성을 확보하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.333-344
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• 1999

Currently many studies on the unmanned gantry crane for the automated container terminal are accomplished. This is needed for the development of large scale, automation, high speed, unmanned system and information system in port facility. In order to do efficient container handling job in port yard, the automated handling system is well adapted to the job environments and all-season weather, In order to realize the automatic and unmanned system for container handling job, the required functions and main structure system are studied. The major problems of operation of the conventional gantry crane are that the vibration of gantry structure body is occurred by operation and that high-speed and precision position-velocity control and the capability to dope to the external disturbances caused by the wind, rain, fog and job environments. In this paper, the fundamental study for establishment of the concept and the dynamic modelling of the major sub system of the unmanned gantry crane is presented. These studies are useful for design and manufacturing of the new concept model of the unmanned gantry crane for efficient operation of the automated container terminal.