• Journal of the Korean Geosynthetics Society
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• v.21 no.1
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• pp.23-32
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• 2022

This study is conducted to minimize the problems caused by the difference between the settlement and settlement time of the one-dimensional consolidation analysis by the Terzaghi's consolidation theory, which is generally used in domestic soft soil design, from the settlement and settlement time measured at the field site. Consolidation-time factor considering the field site characteristics can be determined using the relationship among the degree of consolidation, settlement time, and time factor, the time-settlement curve measured at the field is reverse- analysis using a numerical-analysis technique to reproduce the same consolidation behavior as in the field. Time-settlement and time-excessive pore water pressure data when the same consolidation behavior as the site is reproduced Consolidation-time factor of the soil of Songsan Green City by settlement and excess pore water pressure was calculated using the settlement and excess pore water pressure for each settlement time. If the results of this study use the Terzaghi consolidation-time factor, which does not consider the consolidation characteristics of the soft ground target area, it is difficult to determine the end time of the soft ground during construction. It is necessary to use the established settlement-time factor.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.429-429
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• 2021

2019년 발생한 인천광역시 붉은 수돗물 사태로 급수구역에 포함된 26만 1천 세대, 63만 5천 명이 직·간접적인 피해를 입은 바 있다. 경제적 피해액으로 추정할 경우 최소 1,280억 원 이상으로 보고된 바 있으며, 이와 같은 상수관망의 수질사고 확산은 장기간 동안 시민의 건강과 생활환경 수준을 저하시킨다. 따라서 상수도시스템의 수질사고확산 모델링 및 방지기술을 통한 수질안전성의 재확인이 필요하며, 이것은 상수도시스템의 지속가능성을 높여 국민이 체감하는 물 환경 수준 제고에 기여가 가능하다. 관망 내 수질해석을 직접적으로 수행하는 모델은 국외적으로 다양하게 개발(PODDS, EPANET-MSX, EPANET2.2 등)된 바 있으나 검·보정을 위한 수질측정 자료 부족 등으로 적용이 제한적이라는 한계가 현재에도 존재한다. 이를 보완하기 위해 수질자료에 비해 그 양이 많고 획득방법이 상대적으로 수월한 수리학적 계측자료 및 해석결과를 활용한 관로 내 체류시간 등을 활용한 연구가 수행된 바 있다. 그러나 이와 같은 수리학적 해석 결과를 활용하는 경우에도 계측자료를 기반으로 한 수리학적 검·보정은 필수적이라 할 수 있다. 본 연구에서는 관로 내 체류시간에 직접적인 영향을 미치는 유량 및 유속자료를 중심으로 수리학적 관망해석의 결과를 최적 검·보정하는 방법론을 제안하였다. 기존 상수관망 수리해석의 검·보정은 일부 지점에서 수압을 측정하고, 수리해석 결과로 도출되는 해당 지점의 수압이 실측된 결과와 유사하도록 관로의 유속계수를 적절히 보정하는 형태로 진행되었다. 그러나 본 연구에서는 관로유량과 유속자료의 목적함수 내 가중치를 수압자료보다 크게 설정하여 체류시간 중심의 검·보정이 수행될 수 있도록 하였으며, 검·보정 대상인자 역시 대수용가의 수요량, 수요패턴, 그리고 관로유속계수로 확장된 모형을 구축하였다. 최적화 기법으로는 메타휴리스틱 기법중 하나인 화음탐색법을 활용하였다. EPANET 2.2 Toolkit과 Visual Basic .Net을 연계하여 프로그래밍하였으며, 개발된 모형을 실제 지방상수도 시스템에 적용하여 분석하였다.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.487-494
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• 2005

In order to estimated a reason of soil slope failure new measurement technology is demanded to measure a variation of volumetric water content which is a key physical parameter for understanding the slope failure in the field. In this study a laboratory soil tank test were conducted to use RDB and ADR measurement probes for measuring the variation of volumetric water content. These experiments were compared with two physical parameters as volumetric water content and pressure water head which are estimated to the compacted weathered granite soil under the artificial rainfall, 7.5mm/hour, in the whole of two stages. From the results the variation of volumetric water content and pressure water head is represented to nearly similar travel time.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2002.10a
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• pp.78-83
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• 2002

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.429-442
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• 2004

Landslide of the Whanpyeong Mountain which was occurred at Busan Metropolitan City in 1999 belongs to the category of plane failure. Automatic monitoring system to measure horizontal displacement, pore pressure change and load change has operating from reconstruction stage for evaluating rock slope stability (August, 2000$\~$Feburuary, 2002). As a result of the analysis on the monitoring performance data, it is suggested that infiltrated rain water from pound surface discharges rapidly through cut-slope because pressure head of water decreases rapidly after rainfall while rise of pore pressure is proportional to the amount of rain water. As a result of data analyses for inclinometers and load cells, it seems that slope is stablized be cause ground deformation is rarely detected. The areas especially similar to the study site where landslide is induced by heavy rain fall, change of pore pressure is rapidly analyzed using automatic monitoring system. Therefore, it is considered that automatic monitoring system is very effect for slope stability analysis on important cut-slopes.

• Journal of the Korean Geotechnical Society
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• v.22 no.3
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• pp.13-21
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• 2006

Geosynthetic damage has attracted a major attention since the introduction of geotextiles for civil engineering applications. In this study 3 pilot trial embankments were carried out to investigate the behaviours of reinforced embankments over soft cohesive soils and to find the optimum methodology of embankments over soft soils. As the seamed part of polyester mat (PET, tensile strength 15 ton) used in the first full-scale field test was ruptured under progressing rotational slope failure because of unexpectedly rapid construction of embankments, the excessive pore water pressures were measured. On the soil behavior where tension explosion of mat was continued, pore pressure larger than the one caused by embankment height was measured. Especially, at the depth of 5.0 m under the ground pore pressure increased over long term. It was discussed with respect to the height of embankment and heaving behavior of soft soils.

• 연구논문집
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• s.23
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• pp.141-153
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• 1993

본 연구는 국내의 플랜지 전문생산업체에서 제작하여 국외의 정유회사로 공급한 플랜지중 1개가 수압시험중 균열이 발생되어, 이에 대한 원인규명을 하고자 하였다. 먼저 균열이 간 플랜지와 동일재질의 건전한 플랜지를 입수하여 화학성분분석, 기계적 성질, 개재물, 경도측정 및 미세조직관찰을 통하여 비교조사하였고 파괴플랜지 용접부의 조직 및 경도측정으로 용접부의 영향을 조사하였다. 또한 파괴면의 육안관찰, SEM, EPMA 및 XRD분석으로써 균열발생 시기와 상태등을 추정하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.30-30
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• 1997

국내에서는 시도되지 않았던 조립식 맨드렐 및 prepreg 제작 방식을 적용하여 filament winding machine으로 압력 용기(STEB)를 제작, 음향 방출 측정 장비 및 strain gage 등을 부착한 수압 시험으로 압력용기의 구조적 건전성 예측 및 파열 압력을 측정하여 성능을 분석하였다. 동일한 winding pattern 및 조건하에 prepreg winding과 wet winding 방식을 적용하여 제작한 압력 용기의 성능을 비교하였고, prepreg winding의 설계 조건, 공정 변화를 통해 제작한 압력 용기의 파열 압력 및 형태를 분석하였다. 이러한 winding 조건들에 따라 제작된 압력용기는 최종적으로 PR(Performance ratio) 값을 산출하고, 이를 통하여 prepreg 제작 방식의 장단점, 제작에 필요한 설계 조건 및 기초 자료 등을 고찰하여 보았다.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.1-11
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• 1997

During hydroproof test of composite pressure vessel, acoustic emission signal was measured and analyzed to evaluate structural integrity of composite motor case. When pressure was held for 1 min. at constant pressure from low pressure level to high pressure level, the pattern of hit rate of good composite pressure vessel is increased with higher value than that of bad composite pressure vessel. This report also presents detection possibility of burst location approximately in the range of 25∼36％ of burst pressure using energy rate. In case that it is difficult to detect burst location of composite motor case, it is possible to detect burst location, i.e. structurally weak location of composite pressure vessel with applying same pressure lower than maximum expected operating pressure(MEOP) repeatedly.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.291-298
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• 2008

Cracks in concrete generally interconnect flow paths and increase concrete permeability. The increase in concrete permeability due to the progression of cracks allows more water or aggressive chemical ions to penetrate into concrete, facilitating deterioration. The goal of this research is to study the relationship between crack width and water permeability of cracked concrete. Tests have been carried out as a function of hydraulic pressure (0.1 $\sim$ 2 bar) and crack width (30 $\sim$ 100 ${\mu}m$). Splitting and reuniting method was used to manufacture cracked concrete specimens with controlled crack width. Crack widths are checked by using a microscope($\times$100). The results show a considerable increase of water transport with crack width and hydraulic pressure. When the crack width is smaller than 50${\mu}m$, the crack width has little effect on concrete permeability. Due to the autogenous healing, the water flow through the crack gradually reduces with time. When crack width is 100 ${\mu}m$ and hydraulic pressure increase from 0.1 bar to 0.25 bar, concrete permeability increases rapidly about 190 times according to the test results.