• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.714-717
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• 2011

본 논문에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어로프와 선체블록 간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하고, 외력 계산 커널은 비선형 유체정역학적 힘, 선형 유체동역학적 힘, 풍력, 계류력을 계산할 수 있다. 이를 이용해 블록에 작용하는 와이어로프와 블록 간의 간섭과 동적 접촉력을 계산하고, 그 결과를 이용하여 러그가 부착된 블록의 구조 해석을 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.501-509
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• 2010

A floating crane is a crane-mounted ship and is used to assemble or to transport heavy blocks in shipyards. In this paper, the static and dynamic response of a floating crane and a heavy block that are connected using elastic booms and wire ropes are described. The static and dynamic equations of surge, pitch, and heave for the system are derived on the basis of flexible multibody system dynamics. The equations of motion are fully coupled and highly nonlinear since they involve nonlinear mass matrices, elastic stiffness matrices, quadratic velocity vectors, and generalized external forces. A floating frame of reference and nodal coordinates are employed to model the boom as a flexible body. The nonlinear hydrostatic force, linear hydrodynamic force, wire-rope force, and mooring force are considered as the external forces. For numerical analysis, the Hilber-Hughes-Taylor method for implicit integration is used. The dynamic responses of the cargo are analyzed with respect to the results obtained by static and numerical analyses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5323-5329
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• 2013

Many companies have tried to develop the horizontally vibrating linear motor, for sliming the smart phone. Mathematical modeling and analysis is one of method to simulate the dynamic performance of the horizonatally vibrating linear motor. However, the horizontally vibrating linear motor vibrates in twisting mode because there are two kinds of force acting on the vibrating part. One is are the horizontal force by Lorentz force. The other is the vertical force by attraction force between magnet of vibrating part and bracket and the gravity force of vibrating part. However, those are very difficult to be included in mathematical modeling which generate the simulation errors. In this paper, we perform MFBD (multi flexible body dynamics) simulation using commercial dynamic analysis program "DAFUL". In our new model, the force effects those are neglected in mathematical model, are included. For the verification, the simulation results are compared with the experiment results with manufactured prototype.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.375-380
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• 2012

In this study, dynamic load and dynamic contact force between a building block and wire ropes of a goliath crane are calculated during lifting or turn-over of a building block for the design of an optimal lug arrangement system. In addition, a multibody dynamics kernel for implementing the system were developed. In the multibody dynamics kernel, the equations of motion are constructed using recursive formulation. To evaluate the applicability of the developed kernels, the interferences and dynamic contact force between the building block and wire ropes were calculated and then the hull structural analysis for the block was performed using the calculation result.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.95-104
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• 2002

The theoretical and analytical studies on dynamic signals(force and acceleration signals) measured at SPT rod are actively made. In this paper, the characteristics of stress wave(force signals) in SPT rod were studied experimentally using model rod system. It was noted that the amplitude ratios of reflected wave over incident wave in different end conditions were well matched with theoretical results. The impedance of soil could be determined if the characteristics of incident and reflected waves could be evaluated quantitatively in situ SPT test. On the other hand, the results of model tests showed that the effect of reflected wave caused by side friction was negligible, and therefore, the analysis model considering only end resistance of sampler could be applicable in dynamic analysis of SPT.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.56-60
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• 1995

본 연구에서는 기존의 연구에서 다룬바 없는 분포하중의 경우에 대해 스펙트럴요소법을 적용하기 위해 1) 힘과 변위와의 관계를 이용하여 Bernoulli-Euler보와 1차원 Timoshenko-Mindlin평판에 대한 스펙트럴요소를 유도하고 2) 스펙트럴 요소법을 이용하여 분포하중을 받는 이들 구조물의 동적거동을 해석하고자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.4
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• pp.1-9
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• 2010

Fuel shutoff valve of a gas generator controls propellant mass flowrate of a rocket engine, by using pilot pressure and spring force. The developing fuel shutoff valve can be self sustained even though pilot pressure is removed in an actuator. Therefore, it is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure for the opening of the poppet and to determine the working fluid pressure at which the valve starts to close. This paper also has been designed dynamic model using the AMESim and predicted flow coefficient of the valve by Fluent CFD analysis. Various results from the prediction and the analysis have been compared with experiments. Finally, dynamic characteristics of the valve have been verified with experimental results.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.279-282
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• 2000

진동가속도를 감지하는 힘평형 서보 가속도계의 성능특성을 결정하는 질량지지 장치를 4개의 팔로 구성된 형태로 설계하고 응답특성을 조사하였다. 스프링의 길이, 폭, 두께에 따른 질량지지 장치의 응답특성을 유한요소법을 이용하여 계산하고, 이를 바탕으로 힘평형 서보 가속도계의 감도, 사용주파수 범위 및 동적 범위를 예측하였다. 그리고 레이저 간섭계를 이용하여 힘평형 서보 가속도계의 각각의 진동 주파수 및 가속도의 크기에 따른 간섭무의 수의 변화와 이때의 응답전압간을 이용하여 가속도계의 응답특성을 측정하였으며, 수치해석을 통해 얻은 결과와 비교 분석하였다.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.715-725
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• 2000

As a link composition of a double link type level luffing jib crane was determinated through the link composition design, the design to be considered will be computations of the luffing trajectory deviation at the fly jib tip and the required luffing device capacity. This paper is a study regarding the static and dynamic analysis for a mechanism of the crane. The objective of the static analysis is to determinate the capacity and the dimension of luffing device when the crane selfload, rated hoisting load, wind load and inertia force are applied on the crane. The objective of dynamic analysis is to compute the luffing trajectory deviation, velocity and inertia force due to luffing acceleration for each link. All analyses are performed by computer programs. The reliability of the program was checked by results from analyses of the related commercial package. It is expected that the productivity and reliability of the design can be improved by this program which can rapidly and exactly deal with static and dynamic analysis for a given link composition of the crane.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.10-17
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• 2003

Dynamic stability is critically required to stabilize an airship which is statically unstable. Numerical computations were performed in order to support and confirm the foced oscillation wind tunnel tests. To analyze the low-speed flow filed around the airship, a low-Mach number preconditioned method was applied. Using two computation methods, variations of the dynamic damping coefficients were examined. Numerical results show that it is dynamically stable for three directional moments, but unstable for normal or side force. It is revealed that the damping coefficients are more sensitive to the direction of the angular rate than the angle of attack or the magnitude og angular rate.