• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.541-548
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• 2012

The hollow slab has advantages that its self-weight does not greatly increase notwithstanding the increase of its thickness and its flexural performance does not significantly degrade in comparison with general reinforced concrete slab. However, the utilization of the hollow slab is currently being underestimated in spite of structural system that enables economic design of building and construction of eco-friendly structure. the significant reasons for this situation is that the method of structural analysis and design for hollow slab is not generalized. In this study, to consider practical compressive zone of hollow slab, the equation for its flexural strength is proposed by the volume of compressive stress block according to neutral axis location in hollow section assumed. Existing estimation method of flexural strength of hollow slab considering only compressive zone above hollow part is evaluated as the most conservative method and the method estimating flexural strength by two alternative cross-section of hollow slab is evaluated as more practical method.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.640-649
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• 2017

A comparative research on the traditional standard wood walls and other light-frame wood walls is necessary to expand the base of wooden buildings and improve consumer satisfaction. Therefore, in this research we looked for new possibilities through comparison of performance between standard wood wall and newly presented staggered stud wood wall. First, the strength characteristics of staggered stud wood walls were evaluated and the those of standard wood walls were compared. The ultimate load of the standard wall was larger than that of the staggered stud wood wall, because the cross section of the wood making up the standard wood wall was larger than that of the staggered stud wood wall. However, the statistical analysis between the two groups didn't showed a significance of 95% confidence level. This means that, staggered stud wood walls have shown the possibility of replacing the standard wood wall. Because the cross-section of the stud in the staggered stud wood walls is smaller than that of the standard wall, the material can be saved. Therefore, staggerd wood stud wall is judged to be more economical than the standard wall. In addition, since the area of the insulation also increases, improvement of the heat bridge is also expected.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.817-824
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• 2010

The concrete containment structures have been widely used in nuclear power plants, LNG storage tanks, etc., due to their high safety and economic efficiency. The containment structure consists of a bottom slab, wall, ring beam and dome. The shape of the roof dome has a very significant effect on structural safety, the quantity of materials, and constructability; the thickness and curvature of the dome should therefore be determined to give the optimum design. The ring beam plays the role as supports for the dome, resulting in a minimized deformation of the wall. The main issues in designing the ring beam are the correct dimensions of the section and the prestress level. In this study, an efficient design procedure is proposed that can be used to determine an optimal shape and prestress level of the dome and ring beam. In the preliminary design stage of the procedure, the membrane theory of shells of revolution is adopted to determine several plausible alternatives which can be obtained even by hand calculation. Based on the proposed procedures, domes and ring beams of the existing domestic containment structures are analyzed and some improvements are discussed.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.95-104
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• 2006

For the interests in the economical and safe design of foundation system, the concern on the piled raft or disconnected piled raft foundation system is increasing now. In this study, the behavior and the effects of the disconnected piled raft foundation not studied actively in this country were examined using the triaxial compression tests in place of laboratory model tests. The triaxial test samples were prepared with Jumunjin standard sand and the carbon rods, which simulate the ground soil and piles respectively. After the sample in which carbon rods were arranged was laid inside the triaxial chamber, the confining pressure was applied and then loading test was conducted. To analyze the reinforcing effects of the disconnected piled raft foundation, a few number of tests were carried out by changing the number, the diameter and the length of the model piles. As a result of this study, in the disconnected piled raft foundation system, even though the number of pile is few and the diameter of pile is small, the settlement of the foundation system decreased greatly.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.53-63
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• 2009

Use of high-strength steel members in building of high-rise buildings and large scale structures is expected to increase the effectiveness of structural design by reducing the weight and cost of structures. So far, high-strength steel members have been used in a very limited way because it is hard to select the proper strengths of steel members in a systematic way with the consideration of the structural cost. In this paper, therefore, a structural optimization technique based on Genetic algorithm is developed for effective use of high-strength steel members in structural design of high-rise buildings with the form of building frame system. The stability and efficiency of the technique is evaluated by using to a 35-story building. As a result, a stable and reliable optimal solution was obtained with a difference of 2.63% between individual and mean optimal structural costs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.1
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• pp.67-73
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• 2012

Coastal erosion and its impact on human activities as well as the economic damage and environmental conservation of coastal area is one of major concern in the national policies. In this study, we conducted physical investigations to evaluate effects of erosion in the Geojin beach, which is located nearby the Geojin Port, for a detecting of shoreline change and beach cross-sectional area. The results showed that significant coastal erosion of the Geojin beach has occurred by the complex resources of natural factor, such as rising sea level, storm surges, high wave, and man-made construction. Especially, due to the sand supplement from Jasan river, the section which is nearby the estuary of Jasan river is maintained as a stable beach, whereas beach erosion of the other site in GW04 section has been increased indeed. Therefore, we suggest that it is need to continuous monitoring using DGPS and various surveying techniques to prevent beach erosion onto the GW04 section.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.398-398
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• 2020

대도시 상류부에 위치한 댐의 과도한 방류 또는 급작스러운 붕괴는 대규모의 인명 또는 재산피해를 야기할 수 있으며, 다양한 댐 유입량 조건에 따른 침수양상을 파악하는 것은 수재해 대응능력 향상에 필수적이다. 그러나 다양한 과다한 댐 방류 또는 붕괴유량에 따른 침수 범위는 도시의 내수침수와 달리 매우 넓은 지형조건을 고려하며 침수 범위가 광범위하게 나타날 수 있다. 이는 다양한 댐 유입량 조건에 따른 침수 지도를 생성 및 파악하는데 어려움을 가중시키며, 특히 댐 운영에 따른 침수양상을 실시간으로 파악하는데 어려움을 가중시킨다. 본 연구에서는 저빈도부터 PMF(Probable Maximum Flood) 조건까지의 다양한 댐 유입량자료를 바탕으로, 1차원 하천홍수해석을 실시하였다. 연구 대상으로 팔당댐에 대한 댐 해석을 실시하였으며, 팔당댐 하류에 위치한 서울시에 대한 영향을 분석하였다. 1차원 해석 결과로 산정되는 각하도 단면 별 홍수위자료와 GIS을 연계하여 다양한 발생빈도를 나타내는 유입량에 대한 침수지도를 생성하였으며, 기존에 제시된 발생빈도에 따른 침수지도 외에 임의 빈도의 침수지도를 실시간으로 생성할 수 있는 랜덤포레스트 회귀 모형을 구축하였다. 위의 과정들을 통해 다양한 유입량 조건에 따른 연구대상 지역에서의 침수예상도를 분석할 수 있었으며, 서울시 전반적으로 나타날 수 있는 침수심의 공간적 분포를 파악할 수 있었다. 주어진 침수 지도를 이용하여 서울시에 대한 인구 및 건축물의 경제적 가치 자료를 이용하여 추가적인 홍수 위험도 분석이 가능할 것으로 보이며, 임의 빈도에 대하여 실시간으로 침수를 예측할 수 있는 랜덤포레스트와 연계할 수 있다. 제시된 방법론은 댐의 과다한 방류량과 붕괴 현상을 재현하며, 도시의 수재해 대응능력 향상을 위한 기초자료를 제공할 수 있을 것으로 보인다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.1
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• pp.11-26
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• 1984

The aim of this study is to establish a synthetical optimal method that simultaneously analyze and design reinforced concrete flat slab-column structures involving multi-constraints and multi-design variables. The variables adopted in this mathematical models consist of design variables including sectional sizes and steel areas of frames, and analysis variable of the ratio of bending moment redistribution. The cost function is taken as the objective function in the formulation of optimal problems. A number of constraint equations, involving the ultimate limit state and the serviceability limit state, is derived in accordance with BSI CP110 requirements on the basis of limit state design theory. Both objective function and constraint equations derived from design variables and an analysis variable generally become high degree nonlinear problems. Using SLP as an analytical method of nonlinear optimal problems, an optimal algorithm is developed so as to analyze and design the structures considered in this study. The developed algorithm is directly applied to a few reinforced concrete flat slab-column structures to assure the validity of it and the possibility of optimization From the research it is found that the algorithm developed in this study is applicable to the optimization of reinforced concrete flat slab column structures and it converges to a optimal solution with 4 to 6 iterations regardless of initial variables. The result shows that an economical design can be possible when compared with conventional designs. It is also found that considering the ratio of bending moment redistribution as a variable is reasonable. It has a great effect on the composition of optimal sections and the economy of structures.

• The Science & Technology
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• v.27 no.9 s.304
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• pp.86-91
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• 1994

미국과 북한간의 핵회담이 급진전하고 있다. 북한이 그 동안 취했던 애매 모호한 태도를 바꿔 흑연감속로 동결을 대가로 발전용 경수로 전환 지원과 화력발전소 건설, 낡은 송ㆍ변전시설 교체ㆍ보수 등 구체적인 제안을 내논 것이다. 미국은 이를 긍정적인 제안으로 평가하고 수용할 가능성을 보임으로써 미ㆍ북 회담의 성사가능성을 밝게 했다. 북한의 돌연한 태도변화는 김정일체제의 단면을 짐작케할 뿐 아니라 북한이 그 동안 핵카드를 어떤 목적으로 사용해 왔는 지도 극명하게 들어났다. 북한은 핵을 마지막 생존 수단으로 보고 개발에 착수했고 이를 체제유지의 경제원조에 초점을 맞추어 흥정했던 것이다. 그 동안 북한은 과연 어느 정도의 핵능력을 갖고 있었기에 핵카드를 미국과의 흥정에서 최대한 활용한 것이었을까. 문답으로 「북한 핵, 무엇이 문제인가」그 전모를 점검해 보았다.

• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.132-134
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• 2008

본 연구에서는 도로교 설계 기준 바탕으로 H-형강을 사용하여 20~30m 사이의 지간장을 가진 중 소규모 교량에 적용이 가능한 초간편 교량에 사용될 최적 H-형강 선정에 대한 설계 방법을 제시하고 있다. 본 연구는 구조적 안정성을 확보하고, 가로보를 생략한 단순구조를 갖으며, 도로교 설계 기준을 적용한 초간편 H-형강 교량의 경제적이고 합리적인 설계의 방법을 제공 하고 있다.