• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.63-72
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• 2011

The high capacity bi-directional pile load test is an optimum pile load test method for high-rised buildings. Especially, a high pressure and double-acting bi-directional pile load testing, a special type of the high capacity bi-directional pile load test, is the most practical way to overcome limitations of loading capacities and constraints of field conditions, which was judged to be a very useful test method for requiring high loading capacities. Total of 2 high capacity bi-directional pile load tests(P-1 and P-2) were conducted in high-rised building sites in Korea. Based on the field load test results, the sufficiency ratio of loading capacities to design loads for P-1 and P-2 were 3.3 and 2.1, respectively. For P-2, the load test could not verify the design load if 1-directional loads applied slightly smaller than the actual applied load. Also, high capacity bi-directional pile load tests were difficult to determine an ultimate state of ground or piles, although the loads were applied until their maximum loads. Hence, finite element analyses were conducted to determine their ultimate states by calibrating and extrapolate with test results.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.171-182
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• 1994

Recently, several prestressed concrete box girder bridges have experienced severe cracking along the tendon path when prestress force has been transferred to the anchorage zone. The purpose of the present study is therefore to explore characteristics of the local stress distribution, to study the effects of section geometry of anchorage zones, i.e., tendon inclination, tendon eccentricity and concrett. cover thickness anti to develop recornrncnd;itions for specific design criteria for post~tensioned a:lchorage zones. 7'0 accomplish these objectives, a cc~mprehen sive nonlinar finite element study has been conducted. From this study, realistic forrnulas for crackinq and ultimate load capacities are proposed. 'These equations reasonably well predict the crackinq and ultimate loads of prestressed concrete anchorage zones.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.58-69
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• 2014

To cope with sever accident like Fukushima accident, the emergency response system is needed. It consist of the hardened I&C system and the mobile control station. The hardened I&C system monitors the state in the nuclear power plant and controls the emergency equipment such as valves, pumps and the mobile control station placed at 30km away from nuclear power plant receives the status information from the hardened I&C system and transmits the control data to the hardened I&C system. In this paper, we design the emergency communication system connecting the hardened I&C system to the mobile control station and analyze the performance of the system. This system consists of the terrestrial communication system and the satellite communication. The performance such as a communication link budget, throughput and delay time is analyzed for each system.

• Journal of the Korean GEO-environmental Society
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• v.9 no.1
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• pp.5-10
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• 2008

In this study, laboratory model test was performed to estimate pullout behavior of pipe type anchor with surface roughness, embedment and diameter. The design of buried pipe anchors in areas of vertical ground movement is governed, in part, by magnitude of the forces imposed on the pipe and displacements at which they are developed. In this paper, uplift resistance and displacement characteristics of pipe anchors caused by ground condition and embedment ratio, surface roughness, pipe diameter through the analysis of pipe anchor model test were compared and analyzed. The test results of the buried pipe showed that as the relative density increases, ultimate uplift resistance increase in 20%. When pipe anchor is failed with the relative density of the ground, the change of surface roughness, it was shown that the deformation increases as the ratio of penetration increases from 2 to 8 in five times approximately. And most anchor-based theories overestimate the breakout factor.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.344-344
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• 2023

최근 기후변화에 따라 극한 강우로 전 세계적으로 국지적 홍수 피해가 증가하고 있다. 또한 극한 강우 발생시 다양한 건설 현장의 상황에 따라 침수 취약성이 나타나 인적 물적 피해로 이어질 수 있다. 특히, 시공에 따른 현장 지형 변화에 대해 실시간으로 침수 예측이 불가하여 위험 판단이 어려운 실정이며, 극한 강우 발생에 대비하기 위해 강우 정보 획득 및 분석을 효율화하여 강우예측 정확성을 높일 필요가 있다. 이러한 필요성에 따라 본 연구에서는 건설 현장의 침수 피해를 최소화하기 위해 침수 위험을 판정하고 예측하는 방법을 제시하고자 한다. 본 연구의 침수 위험 판정 방법은 건설 현장에서 실시간 지형변화 정보 확보와 침수 위험 판정의 정확도를 높이기 위한 침수심 분석에 인공 신경망 기법을 활용하였다. 또한, 침수판정 알고리즘은 지형, 강우 분석 모듈과 침수판정 모듈로 구성하였다. 지형 분석 모듈은 건설 현장이 시공진행에 따른 지형 데이터의 변화를 고려하기 위해 실시간 영상 정보의 객체 탐지를 구분하는 인공 신경망 기법을 적용해 지형 분석 모듈을 구축하였다. 강우 분석 모듈은 다양한 강우 정보를 취합할 수 있는 서버를 구축하여 강우 임베딩 정보를 실시간으로 분석하도록 고안하여 정확도를 높였다. 이러한 자료를 바탕으로 강우-유출해석에 의한 침수심 값과 실측값, 침수 지표를 활용하여 인공 신경망 기법으로 침수 위험을 판정하도록 제시하였다. 본 연구를 통해 건설 현장에서 지형 상태의 지속적인 변화와 강우데이터의 정확도 향상에 대응할 수 있는 침수 위험 판정이 가능하고 인적 물적 피해 최소화를 기대할 수 있다. 향후, 본 연구에서 제시된 방법은 건설 현장에서 분석 시스템과 실측 모니터링에 의해 검증되어야 할 것이며, 건설 현장 외에도 스마트 도시 및 지하 공간에서 확대하여 적용할 수 있을 것으로 판단된다.

• Magazine of the Korea Concrete Institute
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• v.6 no.3
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• pp.162-172
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• 1994

The flexural and horizontal shear behavior of overlaid concrete slabs with polymer interface is investigated in the present study. An experimental program was set up and several series of overlaid concrete slabs have been tested to study the effect of different surface preparations and dowel bars between old slab and overlay under service and ultimate loads. 'The cracking and ulti mate load behavior for various cases including acryl emulsion treatment and doweled joints has been studied. The present study indica.tes that the overlaid concrete slabs behave integrally with existing bottom slabs up to ultimate range for rough and doweled joints with polymer interface. The pres ent study provides a firm base for the realistic design of two-layered RC slabs in bridges.

• Computational Structural Engineering
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• v.4 no.2
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• pp.111-117
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• 1991

The analysis method calculating the mean and standard deviation for the eigenvalue of complicated structures in which the limit state equation is implicitly expressed is formulated and applied to the buckling analysis by combining probabilistic finite element method with direct differential method which is a kind of sensitivity analysis technique. Also, the probability of buckling failure is calculated by combining classical reliability techniques such a MVFOSM and AFOSM. As random variables external load, elastic modulus, sectional moment of inertia and member length are chosen and Parkinson's iteration algorithm in AFOSM is used. The accuracy of the results by this study is verified by comparing the results with the crude Monte Carlo simulation and Importance Sampling Method. Through the case study of some structures the important aspects of buckling reliability analysis are discussed.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.13-24
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• 1999

The external, unbonded prestressed concrete(PSC) members exhibit very different structural behavior from that of internal bonded PSC members because of eccentricity change and slip occurrence during loading process. The purpose of the present study is to propose the ultimate failure stresses of prestressing (PS) steels for those external unbonded PSC members. To this end, a comprehensive analysis has been made using the nonlinear finite element analysis program developed recently for external unbonded PSC members by authors. A series of major influencing variables have been included in the analysis. It was found that the span-depth ratio, neutral axis depth-effective depth ratio, load geometry, amount of ordinary steel, and prestressing steel ration have great influence for the ultimate failue stress of PS steel is preposed and is compared with experimental dat as well as existing formulas for internal unbonded members. The Comparison indicates that the proposed equation agrees relatively well with experimental data and that existing formulas including ACI and AASHTO equations show some discrepancies from experimental ones. The present study allows more realistic analysis and design of prestressed concrete structures with external unbonded tendons.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.115-121
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• 2002

This report summarized the static test of the rudder system for the KTX-1 basic trainer. The test loads are applied up to the limit and ultimate loads in a stepping sequence. Test loads and test results matt the strength and stiffness requirements of the rudder control system.. Using #004 full scale structure test airframe.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1520-1524
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• 2006

ENSO(El $Ni\check{n}o$ Southern Oscillation)은 태평양상의 해양과 대기간의 복잡한 상호작용의 일부이며, ENSO 순환(ENSO cycle)의 극한상태인 엘니뇨와 라니냐는 세계적으로 발생하는 홍수와 가뭄 등 자연재해와 많은 연관성을 가지고 있음이 많은 연구를 통하여 알려지고 있다. 우리나라에서도 ENSO와 수문변량들간의 관계를 분석하는 연구가 활발히 진행되고 있는데, 수문자료의 변동계수가 크기 때문에 이를 단순 표준화하여 해석하는데 있어 어려움이 있다. 본 연구에서는 자료의 표준정규분포화를 통하여 ENSO와 우리나라 수문변량들간의 관계를 분석하였다. ENSO를 정량적으로 표준지수화하기 위하여 적도부근 남태평양 Tahiti섬과 오스트레일리아 북부 Darwin 지역에서의 기압차를 월별로 표준화(standardization)한 SOI(Southern Oscillation Index)지수를 이용하였고, 수문자료를 정량적으로 표준지수화하기 위하여 우리나라 23개 기상관측소의 월강수량, 12개 기상관측소의 월평균기온, 월최저기온, 월최고기온 자료를 이용하여 표준정규분포를 가지는 표준정규지수로 환산하였다. 환산된 자료의 계절적 영향을 파악하고자 3개월 단위로 구분하여, 초과확률 등을 이용한 분석을 실시한 결과, 특정지역의 수문변동이 남방진동지수와 유의한 상관관계를 가짐을 확인할 수 있었다. 이러한 결과는 현재 많은 연구가 진행되고 있는 수문기상학적 예측모형의 개발에 유용한 정보를 제공해 줄 수 있을 것이다.