• International Journal of Naval Architecture and Ocean Engineering
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• 제9권4호
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• pp.382-389
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• 2017

We are developing a prototype underwater glider for subsea payload delivery. The idea is to use a glider to deliver payloads for subsea installations. In this type of application, the hydrodynamic forces and dynamic stability of the glider is of particular importance, as it has implications on the glider's endurance and operation. In this work, the effect of two different wing forms, rectangular and tapered, on the hydrodynamic characteristics and dynamic stability of the glider were investigated, to determine the optimal wing form. To determine the hydrodynamic characteristics, tow tank resistance tests were carried out using a model fitted alternately with a rectangular wing and tapered wing. Steady-state CFD analysis was conducted using the hydrodynamic coefficients obtained from the tests, to obtain the lift, drag and hydrodynamic derivatives at different angular velocities. The results show that the rectangular wing provides larger lift forces but with a reduced stability envelope. Conversely, the tapered wing exhibits lower lift force but improved dynamic stability.

• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1348-1357
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• 2000

• 동력기계공학회지
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• 제18권2호
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• pp.57-61
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• 2014

Due to the changes of marine transportation industry, it requires ship in larger scale and high speed. In order to operate efficiently, the engine should be work in high power and high horse power. The increase of the number of the propeller blades and the pitch of the screw and the weight, vibration of shafting problems occurs. To evaluate the safety of the system through analyzing the dynamic characteristics propulsion shafting system, was used to prove or to verify the Lalanne & Ferraris model validation.. It indicates that the Program through Campbell diagram and Critical speed map, Root rocus map, to ensure the reliability of the experimental model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.424-429
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• 2008

Aircraft flutter analysis model consists of dynamic FE model and aerodynamic model. Dynamic FE model is composed of stiffness and mass model, and is used for the prediction of normal mode characteristics of the structure. Since aircraft flutter analysis is normally performed in the modal domain, dynamic FE model shall be constructed to describe the modal characteristics of the structure with sufficient accuracy. In this study, dynamic FE modeling method was described using full airframe FE model and structural and system weight data for aircraft flutter analysis. In addition, full airframe dynamic FE model for composite small aircraft was constituted for normal mode and flutter analysis, and the mass modeling results were compared with the target weight data to validate the mass modeling method proposed. Finally, full airframe flutter analysis of composite small aircraft was performed with the dynamic FE model and the aerodynamic model composed.

• 동력기계공학회지
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• 제20권4호
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• pp.19-25
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• 2016

It is needed to use the gait training system for the rehabilitation of the disabled and old people. In this study, a gait training system of turn roller type is proposed for the purpose of helping the rehabilitation. A driving mechanism with the turn roller is designed by using the RecurDyn which is the dynamic analysis program. RecurDyn is used to analyze the dynamic behavior of the gait training system. The static load analysis is carried out to investigate the safety of this system. From the operating test of this system, it is noted that the driving error is little and the load capacity is 130 kgf.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.462-467
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• 2009

Reduction of the structure-borne noise of the naval vessel is very important in order to reduce the underwater radiated noise of it. One of the important factors to reduce the structure-borne noise of the installed machine in a ship is the design of the foundation having sufficiently high mechanical impedance. In this paper, the mechanical impedance of the foundation for the fan-coil unit in a naval vessel is evaluated numerically according to variation of the thickness of the foundation. And also, the forced vibration analysis is conducted considering the dynamic property of the anti-vibration mount. Through the analysis results, it can be known that the dynamic property of the anti-vibration mount should be considered when the minimum level of the mechanical impedance of the foundation is set.

• Journal of Mechanical Science and Technology
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• 제19권2호
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• pp.625-633
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• 2005

A finite element vibration analysis of thin-walled cylindrical shells conveying fluid with uniform velocity is presented. The dynamic behavior of thin-walled shell is based on the Sanders' theory and the fluid in cylindrical shell is considered as inviscid and incompressible so that it satisfies the Laplace's equation. A beam-like shell element is used to reduce the number of degrees-of-freedom by restricting to the circumferential modes of cylindrical shell. An estimation of frequency response function of the pipe considering of the coupled effects of the internal fluid is presented. A dynamic coupling condition of the interface between the fluid and the structure is used. The effective thickness of fluid according to circumferential modes is also discussed. The influence of fluid velocity on the frequency response function is illustrated and discussed. The results by this method are compared with published results and those by commercial tools.

• 한국포장학회지
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• 제8권2호
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• pp.18-26
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• 2002

Films of methylcellulose(MC), chitosan and their blends were prepared using water and acid solution as a solvent. The transition behavior and miscibility of polymers and their blends were characterized by dynamic mechanical analysis(DMA) and thermogravimetric analysis(TGA). The DMA analysis of PEG400/MC blends has shown that PEG400 was compatible with MC and was effective plasticizer since the curves of $tan{\delta}$ against temperature exhibited single peak, corresponding to single glass transition temperature, which were displaced to lower values with increasing PEG400 content. Results of DMA analysis and TGA analysis of MC/chitosan blends indicate that there are some miscibility between MC and chitosan in the blends, attributed to the similarities between two polysaccharides and interactions of two polymers in the blends. The inclusion of PEG400 in the blends increase the miscibility between two components in the blends.

• Journal of Mechanical Science and Technology
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• 제18권11호
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• pp.2009-2020
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• 2004

A parametric study of the factors controlling static and dynamic denting, as well as local stiffness, has been made on simplified panels of different sizes, curvatures, thicknesses and strengths. Analyses have been performed using the finite element method to predict dent resistance and panel stiffness. A parametric approach is used with finite element models of simplified panels. Two sizes of panels with square plan dimensions and a wide range of curvatures are analysed for several combinations of material thickness and strength, all representative of auto-motive closure panels. Analysis was performed using the implicit finite element code, LS-NIKE, and the explicit dynamic code, LS-DYNA for the static and dynamic cases, respectively. Panel dent resistance and stiffness behaviour are shown to be complex phenomena and strongly interrelated. Factors favouring improved dent resistance include increased yield strength and panel thickness. Panel stiffness also increases with thickness and with higher curvatures but decreases with size and very low curvatures. Conditions for best dynamic and static dent performance are shown to be inherently in conflict ; that is, panels with low stiffness tend to perform well under impact loading but demonstrate inferior static dent performance. Stiffer panels are prone to larger dynamic dents due to higher contact forces but exhibit good static performance through increased resistance to oil canning.

• 대한기계학회논문집A
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• 제36권6호
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• pp.699-705
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• 2012

안전벨트의 역할은 차량 충돌이 발생했을 때 운전자를 보호하는 것이다. 그러나 강한 충돌이 발생하게 되면 운전자가 안전벨트에서 미끄러지게 되어 강한 충격을 받는다. 그러므로 이러한 현상을 방지하기 위해 새로운 안전벨트의 개발이 필요하다. 이 연구에서는 새로운 개념의 안전벨트인 Dynamic Locking Tongue(DLT)을 개발하였다. DLT장치는 강한 충돌이 발생했을 때 벨트(Webbing)가 안전벨트에서 미끄러지지 않게 하여 운전자의 피해를 줄여주는 장치이다. DLT장치 개발은 동역학 해석 프로그램인 SAMCEF를 이용하였다. 우선 DLT장치의 유한요소모델을 생성하였다. 그리고 실제 시험방법과 유사한 환경을 만들어 테스트를 해보았다. 이를 통해 DLT장치의 무게와 응력를 구할 수 있다. DLT장치의 최소 강도와 무게를 구하기 위해 반응 표면 분석법을 이용하여 DLT장치의 형상을 최적화하였다. 최적화된 DLT장치를 구조 해석을 통해 신뢰성을 검증하였다.