• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.82-87
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• 2004

The general requirements to achieve the structural integrity of the airframe are described in the military specification, MIL-HDBK-1530. One of these requirements is the durability and damage tolerance of the airframe, which should be shown through the analysis and test based on the related specifications. This paper describes the full scale durability test load simulation to evaluate the structural safety and durability of the advanced trainer, T-50. The test load simulation was performed according to the procedure in the military specification and the KAF contract requirements. The durability test design technique which involve the floating test set-up, the optimal test load simulation method, and the 6-DOF test article balance method to secure the real flight conditions as many as possible. It was confirmed that this method will be available in a similar full-scale airframe structural test in future.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.275-284
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• 1998

Deformation behavior and microcrack development due to uniaxial compressive cyclic loading in the Pocheon granite were investigated using the ultrasonic velocity measurements and the differential strain analysis(DSA). Most microcracks were developed along the direction parallel to the loading axis. Microcracks developed at the early stage of cyclic loading were formed by propagation of pre-existing cracks. Ultrasonic velocity measurement, DSA and measurement of permanent deformation are good tools to represent microcrack development in rock. Since results from each method are slightly different, microcrack development should be interpreted from all three methods. The magnitude of microcracks developed at the early stage of cyclic loading under 80% loading level is twice compared with those under 70% loading level. The highest volumetric crack strain is about 3000, indicating that the Pocheon granite will fail with 0.3% occupation of microcrack in volume.

• Computational Structural Engineering
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• v.9 no.4
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• pp.135-140
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• 1996

Single angle or channel with thin-walled open section can be used as compression member for example as web member in truss. In this case the inevitable eccentricity due to fabrication is commonly neglected in structural design. However eccentricity effect should be considered in the member design, especially in case of compression member. The critical loads of compression members that buckle by twisting or by a combination of bending and twisting are to be determined by solving governing differential equations. In this paper, the investigations are limited to the rolled channels([), equal-leg angles(L), lipped channels(C) and the applied loads are assumed to have some eccentricities.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.307-317
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• 1991

A displacement-based finite element method is presented for the geometrically nonlinear analysis of eccentrically stiffened plates. The nonlinear degenerated shell and eccentric isobeam(isoparametric beam) elements are formulated on the basis of total Lagrangian and updated Lagrangian descriptions. To describe the stiffener's local plate buckling mode, some additional local degrees of freedom are used in the eccentric isobeam element. The eccentric isobeam element can be affectively employed to model the eccentric stiffener just like the case of the degenerated shell element. A detailed nonlinear analysis including the effects of stiffener's eccentricity is performed to estimate the critical load and the post buckling behaviour of an eccentrically stiffened plate. The critical buckling loads are found higher than analytic plate buckling load but lower than Euler buckling load which are the buckling strength requirements of classification society.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.44-44
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• 2004

GPS를 이용하여 대기 수증기의 3차원 분포도를 구하기 위하여, 관측소와 GPS 위성 간 시선방향으로의 수증기에 의한 GPS 신호지연 정도를 결정할 필요가 있다. 이 때 정확성 향상을 위하여 반드시 고려해야하는 위상중심변화(phase center variations)와 조석하중에 의한 지각변위(ocean loading displacements) 등 수직방향 좌표 결정 오차를 유발하는 요인들을 소개한다. 타 연구를 통해 위상중심변화는 크게는 l0cm 이상의 오차를, 그리고 조석하중에 의한 지각변위는 한반도의 경우 최대 3-4cm 정도의 오차를 보임을 알았지만, 이들 오차가 시선방향 습윤지연 결정에 미치는 영향은 규명되지 않았다. (중략)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.669-675
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• 2011

A constant hanger is a device for supporting pipes in plants. It supplies a constant force to a supporting pipe even if the pipe moves because of thermal expansion. In this paper, we propose a method for designing the contour of a cam for a constant hanger. It has been shown that the contour of a cam must satisfy the geometrical relation of the cam, the force balance equation for the load tube, the relation between the side spring compression and the cam rotation angle, and the moment balance equation for the cam. A calculation procedure to solve these equations simultaneously is proposed, and a constant hanger is designed successfully.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.139-145
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• 2018

An outrigger system is used widely to increase the lateral stiffness of high-rise buildings, resulting in reduced dynamic responses to seismic or wind loads. Because the dynamic characteristics of earthquake or wind loads are quite different, a smart vibration control system associated with an outrigger system can be used effectively for both seismic and wind excitation. In this study, an adaptive smart structural control system based on an outrigger damper system was investigated for the response reduction of multi-hazards, including seismic and wind loads. A MR damper was employed to develop the smart outrigger damper system. Three cities in the U.S., L.A., Charleston, and Anchorage, were used to generate multi-hazard earthquake and wind loads. Parametric studies on the MR damper capacity were performed to investigate the optimal design of the smart outrigger damper system. A smart control algorithm was developed using a fuzzy controller optimized by a genetic algorithm. The analytical results showed that an adaptive smart structural control system based on an outrigger damper system can provide good control performance for multi-hazards of earthquake and wind loads.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.535-543
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• 2002

The purpose of this paper is to investigate the slenderness ratio effect on buckling characteristics of thin cylindrical structures subjecting the shear loads in detail. To do this, the buckling strength evaluations were carried out with using the evaluation formulae proposed by J. Okada. From the results of the buckling strength evaluations, the three types of staled cylindrical test specimen, which have L/R=3.1, 1.6, and 1.0, are determined for the numerical analyses and tests. From results, target slenderness ratio over L/R=3 results in dominant bending buckling mode, smaller slenderness ratio under L/R=1 results in dominant shear buckling mode, and near L/R=1.6 region shows the mixed buckling mode which has the bending and shear buckling mode simultaneously. Most results of buckling characteristics obtained by the numerical analyses and the evaluation formulae we in good agreement with those of tests.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.27-34
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• 2015

Dynamic vibration absorbers are widely used in machinery, buildings, and structures, including bridges. Two cases of their usage are considered in this paper. One is a simply supported beam subjected to either a moving force or a sequence of moving forces, which simulates a train-bridge interaction problem. The other is a case where a primary system is mounted on a base that is not grounded and is excited by an external force. The conditions that the dynamic vibration absorbers must meet in these cases are found and compared to those for usual cases where bases of primary systems are grounded.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.459-462
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• 1999

This paper presents a numerical study on the effect of live load pattern on RC flat plate under in-plane compression. Through the numerical study on various live load pattern, the load condition that governs the strength of the flat plate is determined. Effects of L.L/D.L. and arrangement of reinforcement on the behavior of the flat plate are also studied. And the efficient arrangement of reinforcement regarding to live load pattern is proposed.