• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.1
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• pp.110-120
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• 1999

Transient hygrothermal stresses in an infinitely long hollow cylinder subjected to heating in hygroscopic environments at the surfaces are studied. The equations of hygrothermoelasticity based on the plane strain assumption are formulated by considering the coupling effects between heat and moisture. A closed form solution for the transient hygrothermal stresses is obtained by using decoupling techniques and the method of separation of variables. Numerical results including distributions of temperature and moisture concentration are presented. Effects of transient hygrothermal characteristics are clearly shown in both displacements and stress distributions in the wall of hollow cylinder.

• The Journal of the Acoustical Society of Korea
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• v.19 no.6
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• pp.17-22
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• 2000

Statistical Energy Analysis(SEA) is an efficient tool to predict the broadband noise and vibration for the huge and complex structures such as aircraft and ships. To estimate the noise and vibration by using SEA accurately, the characteristics of SEA parameters associated with fluid loading have to be investigated. In this report, the fluid loaded coupling loss factors were calculated for an 'L' and 'T' type line connections and compared to the ones without fluid loading. Then, the vibration levels for steel box model with 'L' and 'T' type line connection were computed using the fluid loaded and no fluid loaded coupling loss factors, respectively. As a result, the calculated vibration levels of the model using the fluid loaded coupling loss factors were lower than those without fluid loading. As a conclusion, it is necessary to use the fluid loaded coupling loss factors for increasing the prediction accuracy on the noise and vibration of immersed structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.789-796
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• 2012

Radiated noise analysis from a ship structure is a challenging topic owing to difficulties in the accurate calculation of the fluid-structure interaction as well as owing to a massive degree of freedom of the problem. To reduce the severity of the problem, a new fluid-structure interaction formulation is proposed in this paper. The complex frequency-dependent added mass and damping matrices are calculated using the high-order Burton-Miller boundary integral equation formulation to obtain accurate values over all frequency bands. The calculated fluid-structure interaction effects are added to the structural matrices calculated by commercial finite element software, MSC/NASTRAN. Then, the impedance and underwater radiation noise due to an excitation of structure are calculated. The present formulation is applied to a ship to calculate the underwater radiated noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.57-61
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• 1991

최근 차량의 고급화에 따라 차실 소음 저감에 대한 연구가 많이 수행되고 있다. 차실의 소음은 주로 엔진 또는 동력전달 장치의 진동과 도로의 요철로 생기는 차체의 진동으로부터 발생된다. 차실에서 20-200Hz의 저주파수대의 소음은 주로 차체 진동과의 연성 효과로 기인한다. 따라서 이 주파수영역에 있어서 소음의 특성을 파악하기 위해서는 차실의 음향 모우드 해석과 차체 구조물의 진동과 차실 음향 모우드의 상호관계를 고려한 구조-음향 연성 해 석이 필요하다. 차실의 음향 모우드 해석을 위해서는 실험적 방법과 유한 요 소법을 이용하는 방법이 있다. 유한 요소법을 이용하여 음향 특성을 결정하 는 경우, 큰 어려움은 없으나 밀폐된 공동에서 경계면을 이루는 구조물의 진 동에 의해 음이 발생되는 경우 단순히 공간의 음향 특성만으로는 음향 응답 을 예측할 수 없게 된다. 즉, 경계면에서 반사되는 반사파는 경계면의 탄성 변위에 의해 운동 특성이 변화되어 반사되므로 입사파와 다른 특성을 가지 게 된다. 따라서 이러한 구조 진동 특성과 음향 특성을 모두 고려한 연성 해 석을 수행하여야 하며, 음향 모우드와 구조 진동 모우드와의 연성에 의한 음 향 응답 특성을 결정하기 위한 수치 해석 프로그램을 개발하게 되었다. 본 연구에서는 전.후 처리 및 사용자 편의성을 염두에 두고 차실소음해석 전용 프로그램(ACSTAP: Acoustical and structural, coupling analysis program) 을 작성하고 이를 실차에 적용하여 유용성을 보였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.50-54
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• 2016

해양사고 원인규명 통합 분석 시뮬레이션 시스템은 해양사고가 발생하는 과정(선회)을 포함하여 충돌, 좌초, 접촉, 전복, 침수 및 침몰 등의 해양사고를 유체-구조 연성 해석기법의 고도 정밀 M&S 시스템을 사용하여 과학적으로 해양사고의 원인을 분석하고 사고의 손상과정을 체계적으로 재현할 수 있는 시스템이다. 해양사고는 육상과 공중에서 발생하는 자동차와 비행기 등의 충돌이나 추락사고와는 달리 공기의 밀도보다 천배의 물에서 발생하므로 물에서 부양되고, 운동하고, 선내에 물이 침수되고, 운항 중일 때 파도도 생성시키고, 두 물체가 근접할 경우에는 압력이 압착되고, 두 물체가 스쳐 지나거나 안벽이나 해저를 근접하여 운항할 경우에는 압력이 저하되는 등 물에서의 연성효과(interface effect)를 충분히 고려하여 재현할 수 있어야 정확하게 해양사고의 원인을 규명 및 분석할 수 있을 것이다. 또한 황천에서 발생하는 해양사고일 경우에는 강한 조루, 강풍 및 해일성 파도 등을 불규칙 스펙트럼을 사용하여 정확히 구현하여야 황천에서 발생하는 해양사고의 원인을 충분히 분석할 수 있을 것이다. 이러한 해양사고 통합 분석 시뮬레이션 시스템을 이용하여 과학적이고 정확한 해양사고의 원인규명 및 분석으로 심판의 획기적인 신뢰 구축과 심판 지연에 따른 사회적 비용을 최소화하고, 해양사고의 원인과 과실 책임, 나아가서 사고 재발방지 대책수립 등에도 활용하는데도 크게 기여할 것으로 사료된다.

• Composites Research
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• v.14 no.6
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• pp.9-15
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• 2001

In the present work, a linear static analysis is presented for thin-walled prismatic box-beams made of generally anisotropic materials. A mixed beam theory has been used to model and carry out the analysis. Several different constitutive assumptions for the shell-wall of the beam section are assessed into the beam formulation. Simple layup cases of box-beams representing bending-torsion or extension-torsion coupled configuration have been considered and tested to clearly show the effects of elastic couplings of the beam. A detailed finite element structural analysis using the MSC/NASTRAN has been carried out to validate the current analytical results. Numerical results show that appropriate assumptions for the constitutive relations are important and crucial for the accurate prediction of beam stiffness constants and also thor the beam behavior.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.95-103
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• 1997

Solvent extraction using aqueous solutions is presumed as one of the most effective methods applicable to in situ conditions without excavation of contaminated soils. Laboratory permeameter soil flushing test is performed to describe the process of solvent extraction of contaminants absorbed on soil particles. When the permeameter tests conducted, diffusion of contaminants through the permeameter flexible-wall was considered for adjusting the remediation percentage. Input and output balance for concentration was well matched in the permeameter tests. Nitrobenzene diffused so excessively (approximately 75%) that it was not suitable for the permeameter desorption tests. No biodegradation was detected in the soil samples.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.492-502
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• 2017

This study, by analyzing two recent television dramas, attempts to identify the ways how popular cultural texts deal with supernatural beings and to discuss political meanings of the ways in the context of neoliberal Korea. The results are: (1) The narratives make a clear line between the supernatural and the ordinary. (2) The supernatural is effectively used in the narratives to extend the boundary of conflict structure towards structural social problems that the society is now facing. (3) When the text resolving the conflicts, the supernatural is also critical, which makes the whle narrative in line with fantasy rather than reality. These results suggest that the conclusion of the previous studies, arguing the use of the supernatural by popular cultural texts tends to function as a form of resistance against neoliberal discourse structure, needs to be negotiated. It is also reaffirmed that we need to explain political meanings of popular cultural texts dealing with supernatural beings, with its double-sided and ambivalent effects.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.113-121
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• 2015

Building using masonry accounts for most of the smaller houses in Korea but due to brittle behavior and low ductility the frequency of usage has decreased in recent years. Despite this, this form of building has been gaining attention overseas for its low cost in construction and environment-friendliness of the materials. As such, many studies are being conducted to resolve the disadvantages in structure. This study produced an specimen for masonry-filled wall and the intersection to confirm the difference in structural movement depends on the existence or lack of expansion joint and verified the reinforcement effect from inserting a connecting steel item (steel plate, stainless steel twist bar). The experiment results show that the specimen with a steel plate inserted saw an increase in durability and an improvement in the strength of the specimens, while the specimen that had stainless steel twists bar inserted saw an increase in ductility that did not cause brittle failure, indicating that the reinforcement effects of inserting a connecting steel item are effective.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.467-473
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• 2002

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load and to provide result for developing improved seismic design criteria. A computer program named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The strength increase of concrete due to the lateral confining reinforcement has been taken into account to model the confined concrete. In boundary plane at which each member with different thickness is connected local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load is verified by comparison with reliable experimental results.