• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.13-22
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• 2004

Ductiluty factor has played an important role in seismic design as it is key component of response modification factor(R). In this stuty, ductility factors() are calculated by multiplying ductility factor for SDOF systems() and MDOF modification factors(). Ductility factors() for SDOF systems are computed from nonlinear dynamic analysis undergoing different level of displacement ductiluty demands and period when subjected to a large number of recorded earthquake ground motions. The MDOF modification factors() are proposed to account for the MDOF systems, based on previous studies. A total of 108 prototype steel frames are designed to investigate the ductility factors considering the number of stories(4, 8 and 16-stories), framing system(Perimeter Frames, PF and Distributed Frames, DF), failure mechanism(Strong-Column Weak-Beam, SCWB and Weak-Column Strong-Beam, WCSB), soil profiles(SA, SC and SE in UBC 1997) and seismic zone factors(Z=0.075, 0.2 and 0.4 in UBC 1997). It is shown that the number of stories, failure mechanisms (SCWB, WCSB), and soil profiles have great influence on the ductility factors, however, the structural system(Perimeter frames, Distributed frames), and seismic zones have no influence on the ductility factors.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.383-393
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• 2007

A simplified model which incorporates the moment-axial tension interaction of the double-span beams in a column-removed steel frame is presented in this paper. To this end, material and geometric nonlinear parametric finite element analyses were conducted for the double-span beams by changing the beam span to depth ratio and the beam size within some practical ranges. The beam span to depth ratio was shown to be the most influential factor governing the catenary action of the double-span beams. Based on the parametric analysis results, a simplified piece-wise linear model which can reasonably describe the vertical resisting force versus the beam chord rotation relationship was proposed. It was also shown that the proposed method can readily be used for the energy-based progressive collapse analysis of steel moment frames.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.2
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• pp.93-100
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• 2021

In Korea, one of the most used structural systems for residential apartment buildings is the combination of the reinforced concrete (RC) wall and rahmen structures in the upper and lower floors, respectively. To alleviate the significant difference between the stiffnesses of these two structural systems, large transfer girders are generally required in the transition zone of the structure, which then results in the use of large amounts of construction materials and low economic feasibility. This paper proposes a new RC boundary-beam-wall system that can minimize the disadvantages of the RC transfer girder system. The structural performance of the proposed system subjected to axial loading was evaluated via rigorous three-dimensional nonlinear finite element analysis. Four parameters, namely the ratio of lower wall to upper wall lengths, distance between stirrups, main bar slope ratio, and slab length, were considered in the finite element analysis, and their effects on the maximum axial load were analyzed and discussed.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.1-14
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• 2022

Moths have a well-developed sex pheromone communication system. Male moths exhibit an extremely sensitive and selective sex pheromone detection system so that they can detect the sex pheromone produced by conspecific females and locate them for successful mating. Using the pheromone detection system, male moths display characteristic stereotypic behavioral responses, flying upwind to follow intermittent filamentous pheromone strands in pheromone plume. The chemical composition of female sex pheromone in moths, typically comprised of multiple compounds, is species-specific. Male moths contain specialized pheromone receptor neurons on the antennae to detect conspecific sex pheromone accurately, and distinguish it from the pheromones produced by other species. The signals from pheromone receptor neurons are integrated and induce relevant behavior from the male moths. Male moths also contain olfactory sensory neurons in pheromone sensilla, specialized for pheromone-related behavioral antagonist compounds, which can enhance discrimination between conspecific and heterospecific pheromones. Here we review reports on the sex pheromone detection system in male moths and their related responses, and suggest future research direction.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.217-220
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• 2009

고층 건물에 대한 구조 안전성 모니터링은 건물 특성상 계측 대상 부재가 많고 하중과 구조반응의 관계가 복잡하기 때문에 센싱 위치 선정의 어려움으로 그 적용에 한계가 있다. 본 논문에서는 고층 건물의 구조 건전도 모니터링을 위한 구조반응 계측위치를 선정하기 위해서 에너지 이론에 근거한 부재의 변위기여도 및 변형에너지밀도 개념을 도입하였다. 보, 기둥, 코어 전단벽, 그리고 아웃리거로 구성된 고층 건물을 대상으로 풍하중에 대한 부재 종류별 부재의 변위기여도 및 변형에너지밀도를 확인하고 전체 구조물의 거동과의 관계를 분석하여 고층 건물의 구조 건전도 모니터링을 위한 센싱 위치를 예상해보았다.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.94-102
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• 1995

The active control system of structural vibration using a hydraulic actuator is developed. The developed system consists of three parts : a hydraulic unit, an actuator unit and a control unit. Structural vibration is sensored by the accelerometer attached to the structure and reduced by the optimally controlled motion of active mass giving anti-phase inertia force to the structure. It is experimentally confirmed that the vibration level of model structure is reduced to about 1/6 by the developed active control system.

• Journal of the Korean Vacuum Society
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• v.11 no.1
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• pp.59-67
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• 2002

The structures and properties of Cu nanowires have been investigated using molecular dynamics simulations. Cylindrical multi-shell Cu nanowires maintain their structures at room temperature and their structural properties are different from the structural properties of nanowires with face-centered-cubic structure. The results from nanopillar and tensile testing of cylindrical multi-shell Cu nanowire showed structures related to pentagonal needle-like crystal structures. Since the subunits of pentagonal nanowire with needle-like crystal are face-centered-cubic structure, pentagonal multi-shell nanowires are stable one-dimensional structures in nanostructured materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.445-450
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• 2003

The moment-curvature envelope describes the changes in the flexural capacity with deformation during a nonlinear analysis. Therefore, the moment-curvature analysis for reinforced concrete columns, indicating the available flexural strength and ductility, can be conducted providing the stress-strain relation for the concrete and steel are known. The moments and curvatures associated with increasing flexural deformations of the column may be computed for various column axial loads by incrementing the curvature and satisfying the requirements of strain compatibility and equilibrium of forces. Clearly it is important to have accurate information concerning the complete stress-strain curve of confined high-strength concrete in order to conduct reliable moment-curvature analysis to assess the ductility available from high-strength columns. However, it is not easy to explicitly characterize the mechanical behavior of confined high-strength concrete because of various parameter values, such as the confinement type of rectilinear ties, the compressive strength of concrete, the volumetric ratio and strength of rectangular ties, etc. So a stress-strain confinement model is developed which can simulate a complete inelastic moment-curvature relations of a high-strength reinforced concrete column

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.175-182
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• 2001

Effective length factor approach for framed column design has long played an important design-aid role. This approach, however, is effective only when the columns are in the form of prismatic or uniform cross sections. Structural engineers who have to design or analyse framed columns with variable cross sections need some means to do their job. By using the finite element method, the stability analysis of the isolated compression members with variable cross sections and that of the framed columns are performed. The parameters considered in the stability analysis are taper and sectional property parameters of the columns, the second moment of inertia ratio of beam to column, and beam span to column height ratio. On the basis of the stability analysis results, effective length factor formulas for the columns with variable sections are derived.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.64-67
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• 2008

The valve applied air pressure type of high pressure packing is developed to prolong the lifetime and to enhance the airtight. The effective valve developed enables to get remove the remaining pressure through the part of valve in handle so that a separate valve to drain is no need. The character of valve developed in this experiment is high packing of valve through special form and having drain hole in stem that enables a drainage regardless the status of vale is closed or opened.