• Journal of Korean Association for Spatial Structures
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• v.11 no.3
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• pp.85-93
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• 2011

Membrane materials are very flexible, thus wrinkling, uniaxial state, can be occurred. The wrinkling are due to lots of various factors as eccentric force, construction errors, and fabrication errors. These wrinkled membrane elements are in status of uniaxial stress. In the paper, a method which be able to check the wrinkling is proposed. The stress-deformation analysis of membrane structures for given external load will be carried out, and here the membrane elements are regarded as wrinkled state if the principal stress 2 is smaller than 0. With proposed method, two existed construction examples, Suwon auditorium and Okinawa 75 Expo, are analyzed.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.398-401
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• 2009

민간 주도형 사회간접자본 (social overhead capital :SOC) 사업은 BOT(build-operate-transfer)를 비롯하여 대상 프로젝트의 정부 정책 등의 여러 환경의 변경에 따라 다양하게 변형되어 적용되어 BTL(build-lease-transfer), BOO (build-own-operate)등의 여러 기법들을 사용된다. 민간 SOC 사업은 프로 젝트의 규모와 장기에 걸친 공사의 불확실성 때문에 프로젝트의 경제성 분석을 하는 것은 복잡하다. 일반적으로 사용하고 있는 현금흐름 할인모형(discount cash flow model; DCF)은 미래의 불확실성 변수들을 적절히 반영하지 못한다는 한계점을 가지고 있지만 현실적으로 많이 쓰이고 있는 방식이다. 본 논문은 옵션기반모형에 근거한, BOT-옵션가치평가(BOT-OV)모형을 국내 민간 SOC 사업의 경제성 분석을 위해 적용한다. BOT-OV모형을 적용하는 것이 기존 순현재가치(net present value; NPV)방식을 통하여 프로젝트 가치 평가 할 때보다 더 정밀한 경제적 타당성 평가를 할 수 있다는 것을 확인하여 기존의 NPV 평가방식의 방법을 대체할 수 있는 가능성을 확인하는데 의의가 있다고 할 수 있다.

• Journal of Aerospace System Engineering
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• v.9 no.2
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• pp.1-6
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• 2015

태양광 고고도 장기체공형 무인기나 인간동력 항공기 등에 사용되는 높은 종횡비를 가진 유연날개는 공력 및 구조 상호작용으로 인하여, 구조적 비선형 처짐 및 양력감소 등의 문제가 발생한다. 본 연구에서는 저속 비행하는 높은 종횡비를 가진 날개의 단방향 공력-구조 연계해석을 수행하였다. XFOIL을 사용하여 공력천이현상을 포함한 저 레이놀즈수 익형 공력특성 자료 확보를 기반으로 3차원 양력선 이론을 사용하여 공력해석 연구를 수행했다. 구조해석은 상용소프트웨어 ANSYS를 사용하여 구조변형이나 응력해석 연구를 수행했다. 단방향 공력-구조 연계해석 결과를 바탕으로 인간동력 항공기 주 날개의 형상설계 연구를 수행했다.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.70-73
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• 2008

Because the inclination and crack of stone pagoda structure are caused by the depth difference of soft soil ground and ground subsidence in weak zone, a long-term conservation of stone pagoda structure is difficult. But it is insufficient to analyze the behavior of stone pagoda structure considering soft soil ground in our country. Therefore, we find the structural effect happening in stone pagoda structure by analyzing mechanically a specific of soft soil ground and carry out structural analysis and structural modelling of stone pagoda structure that considers soft soil ground by discrete element method.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1580-1587
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• 2005

To calculate the long-term allowable strength of geosynthetic reinforcement, replacement method was recommended. The isochronous creep curve by S. Turner was used to define the relation between creep strain and allowable strength. In isochronous curve at given time, one can read the allowable strength at allowable creep strain. The allowable strain gets from specification by directors or manufacturers according to the allowable displacement of reinforced structures. The allowable strength can be determined in relation to the allowable horizontal displacement each structures case by case. The effect of install damage on isochronous behaviors of geosynthetic reinforcement was little. In previous study, install damage increase the creep strain slightly. And the degradation was not identified. But it is supposed that degradation increase the creep strain. In conclusion, The recommended model to determine long-term allowable strength of geosynthetic reinforcements considering tensile deformation of reinforcement and soil is fit for proper, correct and economic design for reinforced earth walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.485-486
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• 2010

In this research, a new analysis method which is able to examine the safety and to assess the serviceability of high-rise buildings from construction period to service life has been developed. The effect of both construction sequence and inelastic behavior of concrete has been considered in the developed analysis method in three dimensions. The more efficient analysis technique and modeling method for practical use were also suggested. For verification of the developed analysis method, the data measured in a high-rise building under construction was compared with the analysis results. Through comparison of the analysis results with the measured data, it was found that the analysis results generally simulated the trend of the measured data well in all cases.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1358-1359
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• 2008

HC(hydrocarbon)센서는 최근 내연기관의 과도상태의 연소 효율 및 배기가스 저감 효율을 높이기 위하여 산소센서와 함께 연소제어 분야에서 많이 사용되고 있다. 현제 HC센서는 전기화학식 및 current limiting 방식을 많이 사용하고 있으며 이는 HC가스의 이온화를 유도하는 촉매를 매질로 하는 전기화학식 센서이다. 이러한 촉매의 경우 장기 사용 시 촉매의 열화 및 변형 등으로 신뢰도가 떨어지게 된다. 본 논문에서는 촉매를 이용하지 않고 HC 가스의 이온화를 위하여 고전압 하전방식의 hydrocarbon센서를 고안하였으며[1], 여러 배출가스를 통한 센서의 전기화학적 성능을 분석하였고 온도 및 HC성분에 따른 전류치 변화를 이용하여 이론적 계산식을 제안하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.35-44
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• 1993

The objective of this study is aimed at developing a new class of polymer concrete, in which hydration of cement and curing of a thermosetting resin can take place simultaneously during the mixing of concrete components. For the selected mix-proportion of the new polymer, the physical and mechanical properties needed for designs are presented. These important properties are compressive strength, flexural strength, split tensile strength, direct strength, fatigue characteristics and fracture parameters. The observed properties are always compared with conventional concrete to serve as reference for engineer in deciding or selecting the proper materials for their projects, and shore protecting structure.

• Journal of the Korean Geophysical Society
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• v.8 no.2
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• pp.97-103
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• 2005

It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Yunhwajae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. The zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists, would not be relatively affected by the weathering process.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.5-12
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• 2004

Soft foundation is extensively distributed in coastal areas including our local regions. Embankment load on such soft foundation causes displacement due to lack of base ground supports. Long-term consolidation can result in settlement and destruction of shear failure and structure. Therefore, a variety of vertical drain methods are applied to construction sites to prevent base from breaking and changing for secure construction. This study analyzed the patterns of changes displacement to determine efficient range of improvement since range of vertical drain material determines vertical and horizontal changes based on the width range of under ground improvement. Changes of intensity with distance from embankment edge were also analyzed in the field study of embankment slope.