• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.270-281
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• 2017

In this paper, a vibratory disturbance to the rotor system generated by gyroscopic precession through helicopter rotor is examined. Also, active vibration reduction method is designed and simulated by designing feedback controller. For this purpose, structural analysis is carried out using EDISON's geometric exact beam program which can analyze the rotor with the cantilever condition. And the aeroelastic analysis is performed by coupling it with the simple aerodynamic model. In order to obtain the real-time structural response, the EDISON program analysis results were modeled by nonlinear equations and the Newton-Raphson method was used for the trim analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.557-563
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• 2016

The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.2
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• pp.113-124
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• 2004

A computer software program, called BIDAS (BIoassay Data Analysis Software) is developed to interpret the bioassay measurement data in terms of intakes and the committed effective dose using the human respiratory tract model (HRTM), gastrointestinal tract (GI-tract) model and biokinetic models currently recommended by the International Commission on Radiological Protection (ICRP) to describe the behavior of the radioactive materials within the body. The program consists of three modules; first, a database module to manage the bioassay data, second, another databasee module to store the predicted bioassay quantities of each radionuclide and finally, a computational module to estimate the intake and committed effective dose calculated with the bioassay quantity measurement values from either an acute or chronic exposure of the radionuclies within the body. This paper describes the features of the program as well as the quality assurance check results of the BIDAS software program.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.73-76
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• 2004

자동 부하 전환 개폐기는 일반적으로 주 전원의 전압 상태를 감시하여 주 전원의 정전이나, 저 전압 이 감지 될 때 주 전원을 개방시키고, 예비 전원으로 신속하게 전환 시킬 수 있는 구동 메커니즘이 필요하며, 주 전원이 정상 상태로 복구되면 다시 예비 전원에서 주 전원으로의 신속한 전환이 요구 되어진다. 본 논문에서 연구되는 자동 부하 전환 개폐기의 구동부는 1개의 구동력으로 2개 선로의 스위치를 동시에 조작하게 할 수 있는 링크 구조와 동작 원리를 간지고 있으며, 이 동작을 안정적이고 신뢰도 높게 조작하기 위해서 개폐기 구동부의 동특성을 구현할 수 있는 동적 모델로 검증하여 재작하였다. 보다 정확한 모델 수립을 위하여 기구 동작 시에 발생하는 부품들 사이의 충돌, 마찰, 유연성 등의 많은 동적특성들을 정밀하게 모사 할 수 있는 유연 다물체 동역학을 적용하였으며, 검증하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.951-966
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• 2017

In this work, numerical analyses are carried out and the behaviors are investigated for three types of double-acting oleo-pneumatic shock absorbers along with the mathematical models proposed in the part I of this work. After presenting each numerical algorithm corresponding to each model, the numerical algorithms are implemented as user-subroutines in MSC/ADAMS commercial multi-body dynamic software. By using the developed user-subroutines, numerical studies are carried out for compression/stretch test as well as drop test. From the comparative studies, we investigated the salient feature of each double-acting oleo-pneumatic shock absorber. Results identifies that it is possible to increase the absorbing efficiency in accordance with the requirements for aircraft landing conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.281-289
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• 2016

Accurate prediction of the trajectory and time of a time-varying mass parachute system remains essential in the mission requiring a precision airdrop to the ground. In this study, we investigate the altitude-varying behavior of a cross-type parachute system designed to deliver a time-varying mass object like flare. The dynamics of the descending parachute system was analyzed based on the Runge-Kutta method of the ordinary differential system. The drag coefficients of the cross-type parachute and flare were calculated by a CFD code based on the incompressible Navier-Stokes equation. Finally, by using a simplified gust wind model in troposphere, the combined effects of gust wind and time-varying mass were examined in detail.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.251-260
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• 1998

We consider the motion of the subsystems as separate bodies as well as the entire satellite for the attitude and orbit control of a communication satellite by multi-body modeling technique. Thus, the system, can be applied to a general communication satellite as well as a specific communication satellite, i. e. Koreasat I,II. The simulation results can be viewed by two-dimensional graphics and three-dimensional animation. The graphical user interface(GUI) makes its usage much simpler. We have simulated a couple of scenarios for Koreasat I,II which are being operated as geostationary communication satellites to verify the system performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.330-340
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• 2009

A naval shipboard inevitably movies in a pitch and roll direction under the influence of wave and wind in the sea. As a result, the shipboard gets in a continuous turning motion back/front and right/left. And the shipboard is also constantly exposed to many different kinds of disturbance signals including the vibrations of various frequencies from the internal equipments and their vibrations, strong waves, and impact from explosion. This paper formulates multi-body dynamic models similar to an actual system and simulates the pitch/roll positions of a 2-axes gimbals with PI controller for consecutive behavior of a naval shipboard including disturbance.

• The KSFM Journal of Fluid Machinery
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• v.14 no.5
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• pp.48-54
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• 2011

Structural modifications of a ship may cause a fatal accident such as sinking and wrecking of ship. Especially, barge ship can be easily reconstructed to load more bulk cargo. In this study, for a real accident case, change of mooring force due to structural modification was analyzed to evaluate accident risk. A two dimensional dynamic model for the barge ship was constructed to compute mooring forces with related to floating motion. The equation of motion was established in Matlab code and buoyancy was calculated by using direct integration of submerged volume. The results showed that wind force, current force, and mooring force after rebuilding was approximately 4.3 kN, 14 kN, 1,561 kN respectively. The maximum force of mooring force according to the length of mooring cable were 1,614 kN at 30 m of mooring cable. Thus, an arbitrary modification of ship lead instability and unreliable result so that illegal rebuilding of ship should be avoided.

• 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.