• The Journal of the Korea Contents Association
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• v.10 no.11
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• pp.446-451
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• 2010

To investigate the vortex induced vibrations the 2-d.o.f. spring mounted circular cylinder was tested in the wind tunnel. The circular cylinder was designed to have the translational and the rotational mode uncoupled to each other. During the wind tunnel tests the resonance behaviors of the translational and the rotational modes by the locking-on phenomena were observed. From the locking-on phenomena observed it is shown that the vortex shedding is correlated with the responses of the structures. And the forces generated by the vortex shedding are influenced by the amplitudes and the frequencies of the cylinders.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.208-212
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• 2001

DQM(differential quadrature method) is applied to computation of two dimensional elasticity problems in helical spring. Elastic shear stresses in an axially loaded helical spring having rectangular and square cross sections are calculated. The results are compared with those obtained using the method of successive approximations. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.468-475
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• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.303-312
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• 2006

This paper presents the equivalent nodal load for the element stiffness which represents the influence of the stiffness change such as the addition of elements, the deletion of elements, and/or the partial change of element stiffness. The reanalysis of structure using the equivalent load improves the efficiency very much because the inverse of the structural stiffness matrix, which needs a large amount of computation to calculate, is reused in the reanalysis. In this paper, the concept of the equivalent load for the element stiffness is described and some numerical examples are provided to verify it.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.900-907
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• 2013

Payload fairing(PLF) protects satellites and related equipment from the external environment. They are separated before the satellite separation. Payload fairing made of composite sandwich materials due to their considerable bending stiffness and strength-to-weight ratio. Payload fairing have compression, shear and bending load during the flight. In this study, To check the strength of PLF and connected part, structural test of PLF accomplished using an actuator and a fixture. Purpose of structural test is to verify the strength of PLF in force of separation spring and combination structural load applied. Test result shows that the PLF have an acceptable margin of safety for the combination structural load and force of separation spring.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.303-312
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• 2008

In this paper, the seismic behavior of shear wal-frame systems is analyzed. The governing equations of the wall-frame systems with outrigger truss are formulated through the continuum approach and the whole structure is idealized as a shear-flexural cantileverwith rotational spring. The effect of shear deformation and flexural deformation of the wall-frame and outrigger trusses are considered and incorporated in the formulation of the wall-frame structures with and without outriggers are compared by using finite element analysis incorporated with the Newmark-${\beta}$ method. Numerical results are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, and provides reason ably accurate results in the early design stage of tall building structures.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.422-424
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• 2012

본 연구에서는 수상위에 진수된 콘크리트 플로팅 폰툰에 상부골조를 단계별로 시공함에 따라 발생하는 추가 처짐이 상부골조에 미치는 영향을 고찰하고 하였다. 이러한 추가변형에 의한 상부골조에 추가 모멘트량을 산정하는 해석절차를 제시하였으며 제시된 절차에 따라 3층 예제 철골 건물을 해석하고 분석하였다. 제시된 시공단계를 고려한 해석 방법과 비교하여, 상부골조를 지반위에 고정하여 모델링하는 일반적인 해석은 수직하중에 의한 변형을 무시하여 설계하중을 과소평가 하며, 플로팅 구조물을 전체적으로 모델링하고 하부 폰툰에 등가의 스프링으로 치환하여 하중을 동시에 재하하는 모델은 과대한 처짐의 영향으로 설계하중을 과대 평가함을 알게 되었다.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.26-31
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• 1992

본 연구에서는 ABBAQUS/EXPLICIT CODE를 이용하여 자동차용 휠 디스크의 성형성을 파악하기 위한 모델링 방식과 컴퓨터 시뮬레이션의 결과인 스프링백, 잔류응력, 두께 변화, 변형률 등을 소개하기로 한다. 컴퓨터 시뮬레이션을 휠 디스크 스탬핑에 이용한 경우 스탬핑시 발생하는 여러현상을 쉽게 예측할 수 있으며, 또한 금형의 Geometry 결정 및 홀더와 펀치의 작용하중 등 금형 설계시 요구되는 데이타 확보가 매우 용이하다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.299-309
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• 2006

Railway noise and vibration has been recognized as major problems with the speed-up of rolling stock. As a kind of solution to these problems, the decrease of stiffness of track pad have been tried. However, in this case, overturning of rail due to lateral force should be considered because it can have effect on the safety of running train. Therefore, above two things - decrease of stiffness of track pad and overturning of rail due to lateral force - should be considered simultaneously for the appropriate determination of spring coefficient of track pad. With this viewpoint, minimum spring coefficient of track pad is estimated through the comparison between the theoretical relationship about the overturning of rail and 3-dimensional FE analysis result. Two kinds of Lateral force and wheel load are used as input loads. Extracted values from the conventional estimation formula and the Shinkansen design loads are used. It is found that the overturning of rail changes corresponding to the change of the stiffness of track pad and the ratio of lateral force to wheel load. Moreover, it is found that the analysis model can have influence on the results. Through these procedure, minimum spring coefficient of track pad is estimated.

• Journal of IKEEE
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• v.20 no.2
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• pp.200-204
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• 2016

In this paper, we have estimated the performance of an overflow valve for EURO type CRDI(common rail direct injection) engine. In order to implement the overflow valve with friendly circumstance, it is necessity for considering spring load. Especially, the performance evaluation of diesel car with accuracy control will be considered a mileage improvement and circumstance regulation. In order to evaluate the performance of overflow valve, The leak test system checks the pressure, switching time and operating time under 3.0 bar below 100 cc, 3.3 bar among 150 cc and 200 cc, finally 4.0 bar upper 250 cc.