• Computational Structural Engineering
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• v.6 no.2
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• pp.5-12
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• 1993

본 고에서는 객체지향설계 및 프로그래밍 기법의 기본적인 개념과 구조설계 전산화에 관한 원론적인 사항에 대하여 고찰하여 보았다. OODP는 이미 S/W 개발분야에서 일반화된 기법이며, 한 때 큰 관심을 모으다 결국 실용화에 실패한 인공지능 또는 전문가시스템고는 달리, S/W 개발 및 유지관리에 큰 발전을 가져오고 있다. 객체 단위에 의한 데이타 및 함수의 통합모듈화, 추상화 및 정보은닉에 의한 객체의 독립성 확보, 객체지향 프로그래밍 언어의 탁월한 이식성, 객체추가에 의한 대규모 S/W의 점진적 개발, 상송성 및 다형성에 의한 프로그램 코드의 재사용성 등은 S/W의 부품화를 가능케 하고 S/W 신뢰도를 크게 높혀 주고 있다. OODP는 구조설계 전산화에도 적합한 기법으로 판단된다. OODP 기법은 전산전문가들의 도구가 아니며 각 분야 전문가들이 자기 분야의 전산화를 위해 사용하는 도구이다. 과거 우리가 fortran을 익혀 구조해석용 S/W를 개발했듯이 이제는 OODP 기법을 익혀 적극적으로 우리 문제에 활용한다면, 우리 분야 전산화 수준을 높히는데 크게 도움이 될 것으로 기대된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.360-364
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• 2001

본 논문에서는 최근의 진화적 구조최적화(ESO) 전략을 회전축의 형상최적화에 적용하였으며, 각 계산 스텝마다 단위 유한요소의 크기를 변경함으로써 기존의 방법보다 빠르고 정확한 최적형상에 수렴하는 새로운 방법을 제시하였다. 축요소의 직경을 시스템 설계변수로 하였으며, 축중량의 감소, 공진배율(Q-factor)의 감소 및 충분한 위험속도의 분리여유를 갖도록 목적함수를 설정하였다. 불평형응답 및 굽힙응력의 구속조건을 부가하였으며, 목적함수에 대한 설계변수의 감도해석을 수행하였다. 전동기축계에 대한 적용 결과로부터 주파수와 동적 구속조건하의 로터베어링 시스템에 대한 축 형상 최적화에 ESO법이 효과적으로 이용될 수 있음을 확인하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.6
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• pp.427-435
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• 2020

Modular structures are relatively lightweight compared to reinforced-concrete or steel structures. However, it is difficult to achieve structural integrity between the columns of unit modules in a modular structure, which causes undesirable effects on the lateral force resistance capacity against wind and earthquake loads. This is more prominent in modular structures whose overall heights are greater. Hence, a post-tensioned modular structural system is proposed herein to improve the lateral force resistance capacity of a typical modular structure. A post-tensioned column-base connection, which is the main component of the proposed modular structural system, is configured with shapes and characteristics that allow inducing self-centering behaviors. Finite element analysis was then performed to investigate the hysteretic behaviors of the post-tensioned column-base connection. The analysis results show that the hysteretic behaviors are significantly affected by the initial tension forces and beam-column connection details at the base.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.474-482
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• 2016

A Kelvin foam plate - widely used in the energy and transport industries as a lightweight structural material - was examined to estimate its Young's modulus using ultrasound. An isotropic tetrakaidecahedron foam structure was designed in SolidWorks and printed using 3D printer with an ABS plastic material. The 3D printed foam structure was used to build a foam plate with a 14 mm thickness ($50mm{\times}100mm$ in size) for the ultrasonic test. The Kelvin foam plate, a significantly porous medium, was completely filled with paraffin wax to enable the ultrasound to penetrate through the porous medium. The acoustic wave velocity of the wax-filled Kelvin foam was measured using the time of flight (TOF) method. Furthermore, the elastic modulus of the Kelvin foam was estimated based on an elastic structural model developed in this study. The Young's modulus of the produced Kelvin foam was observed to be approximately 3.4% of the bulk value of the constituent material (ABS plastic). This finding is consistent with experimental and theoretical results reported by previous studies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.423-434
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• 2001

In this paper, a three-span continuous box girder is analysed by using elastic equation based on energy method, concerning the behaviour with the effects of bending and pure torsional moment. The statically indeterminate forces of a three-span continuous curved box girder are calculated by applying the principle of least work to this elastic equation. The influence line of shear force, bending moment, pure torsion, displacement and angle of rotation due to unit vortical load and unit torque for curved box girder are obtained. The internal forces of the curved box girder which the actual load is applied can be calculated using the influence line obtained from this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6022-6026
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• 2012

This article presents a band-stop filter (BSF) by using a periodic structure property of frequency selective surfaces (FSSs) embedded in a microstrip transmission line. The proposed BSF is designed with FSS unit cells modifying the cross-loop slots. The BSF is interpreted with an equivalent circuit model and a dispersion diagram. The center frequency (fo) of the BSF is 6.6GHz. Proposed filter increases the number of unit cell. As a result, 3dB bandwidth is wider and insertion loss is reduced. Also, Facbricated BSF exhibits uniplanar geometry, simple fabrication.

• Composites Research
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• v.13 no.6
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• pp.63-72
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• 2000

In this paper, statistical treatments of effective properties for plain weave textile composites were presented. Configurations up to 32 layers with varied stacking phase shifts were considered. Effective properties were calculated by numerical simulation in which uni-axial tensile and shear load were applied at unit cell. Sample analysis was utilized to consider the inherent randomness in the phase shift and the results were treated statistically. It was found that effective properties were dependent on stacking phase shifts for thin plain weave textile composites. The distribution of $E_{xx}$ and $V_{xy}$ were skewed and the range of possible values was relatively large. As the number of layers increased, however, the distribution width became narrower and mean values converged. In contrast, $G_{xy}$ was not affected by phase shifts and thickness changes.

• The Journal of the Korean dental association
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• v.32 no.11 s.306
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• pp.805-814
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• 1994

균질화기법을 적용하여 치과 임플란트 시스템에 대한 미세응력해석을 수행하였다. 균질화기법은 하악골내의 해면골과 같은 비균질 비등방성 구조체에 대한 물질모델을 설정하고 이를 이용하여 수치해석시 작은 계산량으로도 해면골조직의 미세단위까지의 응력해석을 가능케 하여준다. 균질화기법을 적용하여 계산된 해면골의 스트레스레벨은 기존의 방법으로 계산도니 수치보다 열배이상 높게 나타났는데, 이는 치과 임플란트 시스템의 응력상태에 대한 기존의 인식과 큰 차이를 보이고 있어 치과 임플란트 설계에 대한 전반적인 검토가 필요한 것으로 생각된다. 또한 균질화기법을 통하여 임플란트 시스템에 대한 측방력의 효과는 매우 크게 나타남을 확인할 수 있었고, 임플란트 시스템의 응력해석시 지나치게 단순화된 유한요소 모델을 사용함으로서 발생되는 오류가 지적되었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.469-476
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• 2007

A domain/boundary decomposition technique is applied to carry out efficient finite element analyses of 3-D contact problems. Appropriate penalty functions are selected for connecting an interface and contact interfaces with neighboring subdomains that satisfy continuity constraints. As a consequence, all the effective stiffness matrices have positive definiteness, and computational efficiency can be improved to a considerable degree. If necessary, any complex-shaped 3-D domain can be divided into several simple-shaped subdomains without considering the conformity of meshes along the interface. With a set of numerical examples, the basic characteristics of computational efficiency are investigated carefully.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.81-89
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• 2003

The simple supported reinforced concrete slab bridges are analyzed by the specially orthotropic laminates theory. This method, however, may be too difficult for some practising engineers. In this paper, the result of analysis for such plate by means of the beam theory with unit width is reported. By using the "correction factor", the accurate solution for the plate can be obtained by the beam theory. The result of this paper can be used for reinforced concrete slab bridges analysis by the engineers with undergraduate study in near future.