• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.584-587
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• 2007

PCS를 비롯하여 WLAN, DMB, W-CDMA, UWB 등의 무선통신 서비스가 증가함에 따라 안테나 동작 대역폭의 광대역화가 더욱 요구된다. 1/4 파장 선형 모노폴 안테나는 구조가 간단하고 전방향성을 갖는 복사특성으로 인하여 가장 널리 사용되는 안테나 중의 하나이다. 모노폴 안테나의 광대역화를 위해서 일반적으로 원통의 직경을 증가시키는 방법을 사용하지만, 평면 모노폴에 적용된 스텝 기법을 적용하여 광대역 특성을 얻을 수 있다. 그러나 스텝 모노폴 자체는 광대역 특성을 나타내지 않으며, 접지면에서도 일정 형태의 스텝 돌출부위가 필요하게 된다. 본 논문에서는 그라운드면의 볼록 계단 구조가 모노폴 안테나의 대역 특성에 미치는 영향을 분석하여 최적의 안테나 급전구조를 도출하고자 한다. 결과의 검증을 위해서 소프트웨어 시물레이션 및 측정결과를 제시한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.453-458
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• 2005

This study deals with elasto-plasticity of granular micro-structures which recovers continuum elasto-plasticity in its counterpart. The theory is based on doublet mechanics that assumes particles of finite size and connecting linear springs, and it makes extensions to plasticity. The result shows that the micro model has one to one relationship with the continuum model in the simplest case. Micro-strain and micro-stress of two dimensional plane stress problem were calculated, which shows the behavior of the specimen and verifies the effectiveness of this model.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.1
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• pp.8-14
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• 2011

This study aims at grasping the structural performances of primary anchor assemblage through a nonlinear finite element analysis. Primary anchor unit may be used as one of the connection devices between ALC panel curtain-wall and RC slab or main frame of a building. From the analytical results structural characteristics such as yield strength, initial stiffness and maximum strength are obtained and fully discussed.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.106-123
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• 1996

This paper experimentally investigates the characteristics of Al-honeycomb sandwich panels which are considered as a promising primary strength member of weight critical large structures. Some tests on the aluminum honeycomb panels subject to 3-point bending or uniaxial compression or crushing load are carried out. Based on the test results, linear elastic response, buckling/ultimate strength and crushing/energy absorption capacity are discussed. Some guidelines for design of aluminum honeycomb panels are given.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.67-75
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• 2011

The present work investigate the effect of sound reinforcement systems on the acoustics of a large dome stadium using a computer simulation. The acoustics of a dome stadium was predicted analyzed by varying room absorption, as well as the configuration of speakers including their directivity, installed height, and numbers. It was found that both D50 and RASTI were improved by increasing room absorption. Larger EDTs were observed according to the increase of room absorption at mid and high frequencies. On the other hand, RT did not show any significant correlation with the changes in room absorption, which might be the effect of a forced linear fitting for non -linear energy decay process. With respect to the speaker configuration, the speech intelligibility of a sound reforcement system installed at higher placed more relied upon their directivity rather than room absorption, Also, lower placing of speakers was found to be effective in decreasing RTs regardless of room absorption.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.6
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• pp.11-23
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• 2002

Computational models up to now for Korean morphology have been linear in that it deal with only segmentation of morphemes rather than formation of the internal structure of a word. When integrating a linear computational model with syntax analysis, it requires an additional interface component between this model and the syntax to bind morphemes into sentence constituents. Furthermore the linear model is not semantically intuitive. In this paper, based on word-syntactical viewpoint, we propose an integrated computational model that deals with morpheme segmentation, formation of syntactic element (sentence constituent), and even internal structure of word. Formalism of two-level morphology is employed to cope with morpheme segmentation and alternation problems, and functional diacritics are proposed to incorporate categorial context into the two-level formalism. A modified GLR-based algorithm is also proposed to check syntactical constraint of morphemes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.417-423
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• 2019

In this investigation, a set of seismic fragility curves for RC bridges in Korea is derived by considering variations of the representative analytical model. The dimensions and specifications of the model are determined, based on statistical analysis of the inventory of RC bridges in Korea. Variations of important modeling parameters such as material properties, size of structural members, and dimension of the bridge are defined based on statistical studies of the bridges. The OpenSees program is utilized for the analysis to represent the inelastic behavior of RC members. A systematic approach is developed to perform a large volume of inelastic dynamic analysis, in which continuous variation of the modeling parameters are programmed to appropriately represent the characteristics of RC bridges in Korea.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.241-248
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• 2015

There are a lot of equipment related to safety and electric power production in nuclear power plants. The structure and equipment in NPPs were generally designed considering a high safety factor to remain in the elastic zone under earthquake load. However it is needed to revaluate the seismic capacity of the structure and equipment as the magnitude of earthquake was recently increased. In this study the floor response due to the nonlinear behaviors of structure was analyzed and the inelastic structural response factor was calculated by the nonlinear time history analysis. The inelastic structural response factor was calculated by the EPRI method and the nonlinear analysis method to realistically evaluate the seismic fragility for the equipment. According to the analysis result, it was represented that the inelastic structural response factor was affected by the natural frequency of equipment, the location of equipment and the dynamic property of structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.417-426
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• 2021

Recently, use of the precast concrete (PC) system, which can increase economy by minimizing field work, has rapidly increased. However, the PC system cannot exhibit structural performance under construction, specifically before integration between members. Furthermore, since it is difficult to secure the structural integrity of beam-column joints even after construction, the PC system is vulnerable to progressive collapse. In the PC system, various types of details for PC beam-column joints have been proposed, while the structural/construction details of PC system generally used in Korea differ from those of overseas PC systems. However, studies on the progressive collapse of the domestic PC system are limited. Thus, in this study, we investigated the structural/construction details of PC beam-column joints mainly used in Korea. Based on the investigation, for the prototype PC system with typical joint details, a nonlinear finite element analysis was carried out to evaluate its structural performance under progressive collapse. Further, a parametric study was performed, and the effect of the design parameters was investigated, to recommend a method to improve the progressive collapse resistance of the PC system.

• Computational Structural Engineering
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• v.2 no.4
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• pp.59-67
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• 1989

Effect of joints which pre-exist in the rock mass on the behavior of underground structures is studied. A finite element program is developed using a constitutive mode for rock masses exhibiting nonlinear anisotropic behavior. The initial loading scheme combined with reduced region of analysis is employed to minimize the problem size. A circular tunnel within rock mass is analyzed and the results are compared with those of elasto-plastic analysis to verify that the program is reasonable. The effect of joint direction is also analyzed in regard to stress relaxation, displacement, and deformation shape. It is concluded that the joint direction has significant influence on the nonlinear behavior of rock masses such that the vicinity of tunnel perpendicular to the direction of the joints is stressed to slide. It is also observed that the circular shape deforms to an elliptical shape with a major axis in the joint direction.