• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.276-279
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• 2011

본 논문에서는 고속도로 대형 추돌사고의 원인이 되는 안개로 인한 시정거리 악화를 개선하기 위한 방법으로 염화칼슘 연소탄, 초미립자 살포기, 강풍기, 건조공기 등을 이용한 안개소산 시스템에 대한 연구를 수행하였다. 국내 환경에 적합한 안개소산 시스템을 개발하기 위해 다양한 안개소산 방법에 대한 현장 성능실험을 통해 검증하였고 강풍기와 열풍기를 결합하여 생성한 건조공기를 통해 공기중의 상대습도를 떨어뜨려 안개를 소산하는 방식이 시정거리 개선효과가 우수하였으며 이를 통해 고속도로 및 터널의 출입구 등 안개 발생으로 운전자의 시정거리가 낮아져 발생하는 사고를 미연에 방지할 수 있을 것으로 기대된다.

• Proceedings of the Korean System Dynamics Society
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• 2005.04a
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• pp.63-74
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• 2005

본 논문에서는 인과지도의 작성자와 독자 간의 심리적 격차에 관하여 분석하고자 한다. 먼저 기존에 연구되어 왔던 소산효과(dissipation effects)와 희석효과(dilution effects)는 인과지도를 작성하는 사람이 아니라 인과지도를 이해하는 사람에게 적용되는 심리적 경향이라는 점을 이 논문에서 지적한다. 소산 효과란 인과고리의 길이가 길어질수록 인과관계의 강도를 낮게 인식하는 심리적 경향을 의미한다. 희석효과는 여러 개의 인과관게가 존재할수록 특정 인과관계의 강도를 낮게 인식하는 심리적 경향을 의미한다. 이들 심리적 경향과는 달리 집중 효과(concentration effect)가 인과지도 작성자의 심리적 경향을 보다 잘 설명하는 것으로 실험 결과 분석되었다. 집중 효과란 주의를 집중하는 영역에 대하여 많은 인과관계를 생각하고, 인과관계의 강도 역시 강하게 생각하는 심리적 경향을 의미한다. 인과지도의 작성자 즉 시스템 컨설팅을 담당하는 사람들에게는 소산효과나 희석효과 보다 집중효과가 더 강하게 작용한다는 것이다. 이러한 심리적 비대칭성이 시스템 다이내믹스 연구자와 그의 고객 간의 의사소통 문제를 야기 시킨다는 점을 본 논문에서 지적한다.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.13-22
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• 2007

Recently, many researches on the dissipation of excess pore pressure in liquefied sand grounds have been performed to evaluate post-liquefaction behavior of structures. In this research, centrifuge tests were performed to analyze liquefaction behavior of level saturated sand grounds. Based on the test results, the evaluation model of solidified layer thickness was developed to simulate non-linear variation of the thickness with time. The thickness evaluation model was combined with the solidification theory and the consolidation theory in order to simulate dissipation of excess pore pressure. The suggested dissipation model properly estimated the solidified layer thickness and the time history of excess pore pressure.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.81-92
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• 2013

The objective of conventional seismic design is to ensure an acceptable safety level while avoiding catastrophic failures of structures and loss of life. Over the last many years, a large amount of research has been devoted into developing effective earthquake resistant systems in order to raise the seismic performance level of structures. The purpose of this study is to propose a new damping system, which realize not only increasing seismic performance but also easy repairing after an earthquake. The proposed damping system is slit in the bottom of wall with damping devices installed in the slit horizontally aiming to dissipate energy during earthquakes. Cyclic loading tests were conducted to investigate hysteretic behavior and energy dissipation capacity. Test results show that the proposed systems exhibit a stable hysteretic response and the energy dissipation in this system is concentrated on the damping devices.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.3
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• pp.77-86
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• 2002

위성은 일단 한 번 발사하고 나면 운용궤도상에서 수리 및 회수가 거의 불가능하기 때문에 위성에 들어가는 모든 개발 부품들은 완벽한 설계, 충분한 해석, 고 작업도의 제작, 그리고 다양한 시험이 반드시 수반되어야 한다. 위성시스템에서 전자 소자의 신뢰성에 영향을 주는 인자는 다양하다. 과도한 열은 전자소자의 실패를 유발해서 결과적으로는 전체 위성의 실패를 유도할 수 있다. 이 논문에서는 다목적 실용위성 2호의 고전력 소산 전장품의 열부하 완화를 위한 방안을 경우별로 연구 비교하였다. 고전력 소산 전장품의 열부하를 완화하기 위해서는 하우징 두께의 증가가 필요하며, 전력조절기의 다이오드나 트랜지스터처럼 전력소산이 큰 소자에 대해서는 장착위치를 변경하거나 장착 부분의 열전도율을 증가시키는 방법이 필요하다. 또한 전력조절기처럼 장착면이 좁은 경우에는 복사의 영향이 크며, 이러한 전장품의 열부하를 완화하기 위해서는 주위 벽면의 온도를 낮추거나 하우징 표면 방사율을 증가시키는 방법이 효과적임이 알 수 있다.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.313-322
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• 2007

The PCS system, which consists of precast concrete column and steel beam, is a kind of composite structural systems. In this paper, experimental study has been conducted to analyze seismic performance of bolted beam-to-column connections for the PCS system. Based on experimental results from the seismic testing of eight interior PCS specimens, it shows that behavior of PCS system is satisfactory to seismic performance criteria of ACI such as strength deterioration, stiffness degradation and energy dissipation capacity except initial stiffness. All of the specimens maintain their strength at large levels of story drift without significant loss of stiffness and show high ductility level for inelastic behavior. The energy dissipation capacity is two times greater than requirement of ACI criterion. But the initial stiffness of all specimens does not satisfy ACI criterion, and this phenomenon is similar to the other composite structural systems such as RCS, CFT system.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.625-632
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• 2015

In this study, a comparative analysis have been conducted to examine seismic reinforcement effect of a school building that is designed with a CBD (Channel Beam Damper) system supported by H-frame with existing non-seismic RC frame. As a result of experiment, seismic reinforcement specimen with CBD system showed hysteretic characteristics of a large ellipse with great energy dissipation ability and increased strength and stiffness, while non-seismic design specimen showed rapid reduction in strength and brittle shear failure at top and bottom of the left and right column. In addition, comparing the stiffness reduction between the two specimens, CBD system was effective in preventing the reduction of stiffness. Energy dissipation ability of specimen reinforced by CBD system was about 4.0 times higher than the non-reinforced specimen. Such enhancement in energy dissipation ability could be considered as the result of improved strength and deformation for further application in designing of seismic reinforcement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.377-387
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• 2014

This study mainly treats a new type of the bracing friction damper system, which is able to minimize structural damage under earthquake loads. The slotted bolt holes are placed on the shear faying surfaces with an intention to dissipate considerable amount of friction energy. The superelastic shape memory alloy (SMA) wire strands are installed crossly between two plates for the purpose of enhancing recentering force that are able to reduce permanent deformation occurring at the friction damper system. The smart recentering friction damper system proposed in this study can be expected to reduce repair cost as compared to the conventional damper system because the proposed system mitigates the inter-story drift of the entire frame structure. The response mechanism of the proposed damper system is firstly investigated in this study, and then numerical analyses are performed on the component spring models calibrated to the experimental results. Based on the numerical analysis results, the seismic performance of the recentering friction damper system with respect to recentering capability and energy dissipation are investigated before suggesting optimal design methodology. Finally, nonlinear dynamic analyses are conducted by using the frame models designed with the proposed damper systems so as to verify superior performance to the existing damper systems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.2
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• pp.87-95
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• 2017

The concept of entransy has been proposed recently as a potential heat transfer mechanism and could be useful in analyzing and optimizing the heat-work conversion systems. This work presents an entransy analysis for the irreversible Carnot cycle by systematic balance formulations of the entransy loss, work entransy, and entransy dissipations, which are consistent with exergy balances. Additionally, several forms of system efficiency are introduced based on entransy for the appreciation of the optimal system performance. The effects of the source temperature and irreversible efficiencies on the optimal conditions for system efficiencies are systematically investigated for both dumping and non-dumping cases of used source fluid. The results show different trends in entransy efficiencies when compared to the conventional efficiencies of energy and exergy, and represent another method to assess the effective use of heat source in power generation systems.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.457-468
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• 2006

An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.