• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1264-1268
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• 2005

본 연구에서는 2002년부터 2004년까지 3년에 걸쳐 한강고수부지(반포지구)에서 수목 식재에 따른 수리적 영향을 수치모형 및 현장조사를 통하여 평가하였다. RMA-2모형을 이용하여 분석한 결과 수목 식재전$\cdot$후로 수위는 3 cm 증가하고 유속은 4 cm/s 감소하는 것으로 나타났다. 따라서 식재로 인한 수리량의 변화는 매우 미미한 것으로 나타났다. .현장조사를 통해 얻은 실측자료도 홍수 시 수목 식재에 의한 하천수리특성에 미치는 영향은 크지 않은 것으로 나타났다. 그러나 매년 홍수기간 동안 보여 지는 침수양상에 따라 수리특성이 상이하게 나타났다. 그러므로 지속적인 자료 수집을 통하여 다양한 침수상황에 다른 기초 수리자료를 축척하고 정밀 분석할 필요가 있다. 또한 수리모형실험을 통해 현장조사 및 수치모형 결과와 비교$\cdot$분석하여 상호보완 할 필요성이 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1602-1606
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• 2009

우리나라는 봄가을에는 산불, 여름에는 태풍 및 홍수, 그리고 겨울에는 폭설 등 항상 자연재해가 많이 발생하고 있다. 2002년 태풍 '루사', 2003년 태풍 '매미' 등으로 인하여 해마다 크고 작은 자연재해가 많이 발생하고 있으며, 많은 재산 피해와 인명피해를 가져 오고 있다. 이에 대해 태풍이나 집중호우 등에 대비하기 위한 방지 대책 및 복구 대책에 대해서는 많이 연구되어지고 있으나, 피해 후 피해조사에 대한 연구는 미흡한 실정이다. 따라서, 본 연구에서는 사진 측량을 이용하여 홍수 피해조사를 위한 지상영상기반 현장조사 시스템을 개발하였다. 지상영상기반 현장조사 시스템은 2개의 스테레오 카메라를 이용하여 피해지역을 촬영하고, 사진측량 기술을 이용하여 피해규모를 파악한다. 모의 적용 결과 줄자로 실측한 값과의 오차가 1m 이내로 발생하였으며, 휴대성이 간편하여 홍수 피해조사 등에 활용될 것으로 판단된다.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.251-252
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• 2008

축전지는 비상용 전원으로 사회 많은 분야에서 다양하게 사용되며, 유사시 예비전원으로 그 중요성이 부각되고 있다. 이러한 경우에 사용가능한 축전지를 선별하고, 그 상태를 체크하는 것은 무엇보다도 중요하다. 본 논문에서는 납축전지의 건전상태 진단을 위해 현장실태조사 및 축전지 진단장비 3종을 통하여 현장실측을 실시하였다. 현장실태 조사결과 납축전지의 유지관리가 미흡함을 확인 할 수 있었으며 또한, 축전지 진단장비 3종을 이용하여 축전지의 임피던스 및 컨덕턴스등의 비교측정결과 사용기간이 오래된 축전지일수록 축전지간의 임피던스 및 컨덕턴스의 편차가 큰 것을 알 수 있었으며 또한 사용기간이 같은 축전지일지라도 그의 설치환경에 따라 축전지간의 임피던스 및 컨덕턴스 편차가 다르게 발생됨을 알 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.553-563
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• 1994

The behavior of earth retaining structure was investigated by considering coupling between soil springs in elasto-plastic soil. For the computation of soil reaction, soil on both sides of walls was simplified as e1asto-plastic springs, and the required horizontal displacement to mobilize Terzaghi's active and passive state was applied to construct the p-y curve. Reliability on computer program developed is verified through the comparison between prediction and in-situ measurements. Based on the results obtained, it is found that the prediction by using coupling between soil springs simulates well the general trend observed by the in-situ measurements. It is also found that the horizontal displacement required for the active state gives a very small effect to the displacement of walls in the sandy soil.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.67-74
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• 2004

A case study was performed to verify the applicability of existing formulae for predicting bridge scour in cases where its piers are founded in fine-grained soils. The object of study was the Kanghwa Choji Bridge area where the streambed consists of mainly clayey soil. Site investigation included: direct measurement of scour depths around piers using an ultrasonic probe; and collection of undisturbed soil samples which were later used to determine geotechnical properties and scour rate under different stream velocities. Scour depth prediction was made by employing several conventional methods and compared with the measured value. All methods, not taking soil's intrinsic property against erosion into consideration, overestimated scour depth by a factor of 3.6 to 6.5. On the other hand, the SRICOS method yielded a reasonably acceptable overestimation by a factor of 1.7.

• Journal of the Korean GEO-environmental Society
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• v.5 no.1
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• pp.47-54
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• 2004

The several computer programs for the design of soil nailed wall are often used in Korea. However, these programs have been used without any practical justification. Therefore, in order to evaluate the applicability of these programs for the design of soil nailing, these computer results were analyzed and compared with one another. The performance evaluations by the available programs, such as SNAILZ, TALREN97, SLOPE/W, STABL6, and NAILM16, were applied and the applied data were from 5 case history(15 section). The estimated factors of safety with available programs were compared with observed horizontal deformation from the field. The results showed that the program SNAILZ is most adequate tool for the design of soil nailed wall.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.103-111
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• 2003

With the proliferation of nonlinear loads such as personal computer in an educational building, high neutral harmonic currents have been observed. High neutral currents in three-phase four ire distribution power systems can cause tots of harmonic problems such as overloaded neutral conductors and malfunction of protective equipment. On-site measurements of harmonic currents and voltages were made and the corresponding equivalent circuits was developed. The circuit model under study was simulated numerically and graphically through the use of the software MATLAB. Simulation results verifying the effect of a single-tuned passive filter for the neutral harmonic current reduction are presented.

• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.41-47
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• 1999

More than 100 bridges in Korea have been annually collapsed or badly damaged by the scouring around bridge piers, particularly in the flood season. To prevent from such a tragedy, the fundamental study on the bridge scouring is required, which is essential not only to estimate the scour depth with reliability but to take it into consideration in its design. However, it is not easy to find out the physical scour mechanism since many factors on the scour are coupled with. Moreover, there exists none of the measured data sufficiently for the primary research on the bridge scour depths. In this study the field measurements are carried out to provide the fundamental data for the research and the design. Scouring depth, pier width, flow depth, and the approaching velocity and degree of pier nose are measured broadly in small and medium streams. From these measurements the present situation on bridge scours can be understood and some of important factors to affect the stability of bridges are analyzed.

• Tunnel and Underground Space
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• v.28 no.5
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• pp.457-475
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• 2018

For increase of reality in numerical analysis, a blasting vibration waveform obtained from field blast operations has been directly used for input parameters of dynamic analysis in the form of vibration velocity. A numerical model was built considering the geological characteristics of underground limestone opening as well as the mining stages in this opening, and the effect of blast operations on stability of underground limestone opening was investigated by dynamic numerical analysis. The adequacy of applying the real vibration waveform to dynamic analysis has been approved from the preliminary analysis, and the dynamic numerical analysis results show that the continuous mining operation can cause the collapse of roof in openings and the active yield zone around openings. Therefore, the additional reinforcements should be applied for ensuring the stability of underground limestone openings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.573-582
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• 1994

Blast vibration equations proposed previously are investigated. Special attention is given to the blast vibration equation which shows the best fitting to the geologic condition of Korea. The fittness of proposed blast vibration equation is analyzed and examined using many field data measured in Korea. The prediction of blast vibration equation using field data was performed by linear regression analysis. Moreover, after the prediction of each blast vibration equation, vibration velocity is recalculated on the basis of scaled distance at each equation. Reliability of regressioned blast vibration equation is observed by comparing predicted and measured velocity, which is divided into small-scale blasting of city and large-scale blasting of quarry. Based on this study, the best fitting equation to the Korean geologic condition is ROOT SCALING & CUBE ROOT SCALING proposed by USBM(United Nations Bureau of Mines). Also representative blast vibration equations depending on the different kinds of rock mass are proposed using measured and existing field data.