• 한국산학기술학회논문지
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• 제19권4호
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• pp.123-131
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• 2018

본 연구는 ${\bigcirc}{\bigcirc}$ 고속국도 공사 중 발생된 이암 절토 사면의 붕괴 요인 분석 및 대책방안을 제시하였다. 기반암인 이암에 대해 실내시험을 수행하고, 국제 기준에 의거해 공학적인 특성을 규명하였다. 그리고 설계 시 수행되었던 사면안정해석을 재검토 하였다. 또한, Swelling-Slaking 현상으로 인해 기반암인 이암의 강도열화특성을 고려한 안정해석을 추가적으로 수행하였다. 기반암인 이암에 대해 Swelling-Slaking Test 결과, 풍화내구성은 낮음-보통으로 나타났으며, 팽창변형률은 매우 낮음으로 나타났다. 설계 안정해석 검토 결과, 이암의 공학적 특성을 고려하지 않고, 한계평형해석을 이용해 실제와 상이한 결과가 나타났다. 강도열화특성을 고려한 추가안정해석 결과, 사면의 붕괴지점과 안정해석의 최대전단변형률 발생지점이 동일하게 나타났으며, 건기시 우기시 모두 기준 안전율을 만족하지 못하였다. 붕괴 사면의 대책방안으로는 사면경사완화공법이 가장 적절하였다. 유한요소해석을 통해 완화 경사를 산정하였다. 완화 경사의 현장 적용성을 위해 시추공영상촬영과 비교한 결과, 미고결된 이암의 대부분이 제거되는 것으로 나타나 미고결된 이암으로 인한 추가적인 붕괴 위험성은 현격히 저하되는 것으로 나타났다.

• 한국전산구조공학회논문집
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• 제30권5호
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• pp.371-380
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• 2017

미국의 내진설계기준인 ASCE/SEI 7-10은 구조물 붕괴성능에 대한 불확실성을 고려하지 않는 등재해도 기반 내진설계의 문제점을 해결하기 위해 위험도 기반 내진설계 개념을 도입하였다. 하지만 현행 국내 내진설계기준의 경우 한반도 내에서 발생한 큰 규모의 지진기록과 구조물의 붕괴성능과 관련된 연구의 부족으로 위험도 기반 내진설계 개념을 반영하지 않고 있다. 본 연구에서는 철골 보통중심가새골조를 표본건물로 선정하여 위험도 기반 내진성능평가를 수행하였다. 건물이 위치한 지역, 높이, 지반조건을 변수로 바탕으로 표본건물에 대한 붕괴성능 평가를 수행하였으며, 국내 지진기록의 특성을 반영할 수 있는 경험적 스펙트럴 형상 예측 모델을 활용하여 지진재해도 곡선을 작성하였다. 이를 활용하여 국내 주요 도시에 위치한 철골 보통중심가새골조의 붕괴확률을 위험도 적분 개념에 따라 평가하였다. 국내 주요 도시에 위치한 철골 보통중심가새골조의 붕괴확률을 평가한 결과, 현행 건축구조기준에 따라 설계된 표본건물은 본 연구에서 고려한 해석 변수에 따라 붕괴확률에 상당한 차이를 보였다. 특히 국내 건축구조기준의 경우 철골 보통중심가새골조에 대한 높이제한이 없어 일부 고층표본건물에서 목표 위험도인 50년간 1%의 붕괴확률을 초과하는 것으로 평가되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1201-1206
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• 2004

Sonoluminescence (SL) characteristics such as pulse shape, radiance and spectrum radiance from submicron bubbles were investigated. In this study, a set of analytical solutions of the Navier-Stokes equations for the gas inside bubble and equations obtained from mass, momentum and energy equations for the liquid layer adjacent the bubble wall were used to estimate the gas temperature and pressure at the collapse point, which are crucial parameters to determine the SL characteristics. Heat transfer inside the gas bubble as well as at the liquid boundary layer, which was not considered in the most of previous studies on the sonoluminescence was taken it into account in the calculation of the temperature distribution inside the bubble. It was found that bremsstrahlung is a very possible mechanism of the light emission from either micron or submicron bubbles. It was also found that the peak temperature exceeding $10^{6}$ K in the submicron bubble driven at 1 MHz and 4 atm may be due to the rapid change of the bubble wall acceleration near the collapse point rather than shock formation.

• 한국지반신소재학회논문집
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• 제15권4호
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• pp.43-52
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• 2016

본 논문에서는 지반 시추 시 공벽붕괴 방지를 위해 사용되는 안정액의 다양한 배합비에 따른 공학적 특성에 대한 실험적 연구를 다루었다. 이를 위해 먼저 배합수가 청수일 경우, 안정액의 공학적 특성을 검토하였으며 아울러 해수 배합시 안정액의 공학적 성능 변화에 대한 공학적 특성을 분석하였다. 그 결과, 청수에서 벤토나이트와 폴리머를 추가할 경우 공학적 성능이 향상되는 것으로 나타났으며, CMC에 비해 Polymer의 증점 효과가 우수한 것으로 검토되다. 또한 해수의 경우 벤토나이트에 비해 내염성점토의 내염성 성능이 우수한 것으로 검토되었다. 따라서 본 논문에서는 시공시 배합수에 따른 안정액을 성능에 대한 정성적인 결과를 제시하였다.

• 대한안전경영과학회지
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• 제4권2호
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• pp.189-197
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• 2002

Composites have wide applications in aerospace vehicles and automobiles because of the inherent flexibility in their design lot improved material properties. Composite tubes in particular, are potential candidates for their use as energy absorbing elements in crashworthiness applications due to their high specific energy absorbing capacity and the stroke efficiency. Their failure mechanism however is highly complicated and rather difficult to analyze. This includes fracture in fibers, in the matrix and in the fiber-matrix interface in tension, compression and shear. The purpose of this study is to investigate the energy absorption characteristics of Gr/E(Graphite/Epoxy) tubes on static and impact tests. The collapse characteristics and energy absorption of a variety of tubes have been examined. Changes in the lay-up which increased the modulus increased the energy absorption of the tubes. Based on the test results, the following remarks can be made: Among CA15, CA00 and CA90 curves the CA90 tube exhibits the highest crush load throughout the whole crush process, and max load increases as interlaminar number increase. Among all the tubes type CC90 has the largest specific crushing stress of 52.60 kJ/kg which is much larger than other tubes.

• 한국생산제조학회지
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• 제21권4호
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• pp.588-592
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• 2012

This study concentrates the effect of hybridisation on the collapse mode and energy absorption for composite cylinders. The static collapse behavior of laminated(Al/CFRP/GFRP) circular-cylindrical composite shell under quasi-static axial compressive load has been investigated experimentally. Eight different hybrids of laminated(Al/CFRP/GFRP) circular-cylindrical composite shell were fabricated by autoclave. Eight types of composites were tested, namely, Al/carbon fiber/epoxy, Al/glass fiber/epoxy, Al/carbon-carbon-glass/epoxy, Al/carbon-glass-carbon/epoxy, Al/carbon-glass-glass/epoxy, Al/glass-glass-carbon/epoxy, Al/glass-carbon-glass/epoxy and Al/glass-carbon-carbon/epoxy. Collpase modes were highly dominated by the effect of hybridisation. The results also showed that the hybrid member with material sequence of Al-glass-carbon-carbon/epoxy exhibited good energy absorption capability.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.749-758
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• 2010

Embankment Slope (or Fill Slope) is defined as artificial slope formed by the filling of soil or rocks on the original ground. Recently a lot of embankment failures and collapse has occurred due to the increase of torrential rainfall and typhoons. Embankment collapse has lead to a great loss of lives and property therefore there is a need to establish a systematic embankment slope management system that will handle the maintenance and repair of risky embankment slopes. The objective of this study is to establish an "Embankment Slope Management Method" for embankment slopes located along national highways all over Korea. The method for field investigation of embankment slopes was recommended and the system for investment priority determination was also developed. The factors that lead to the collapse of embankment slopes caused by natural calamities were also determined through the initial survey of embankment slopes located along river fronts and mountainous areas.

• 한국안전학회지
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• 제30권2호
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• pp.48-55
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• 2015

The number of collapse accidents relevant to form support since 2003 is 30 on the basis of statistical data from Ministry of Employment and Labor,. Total number of casualty was 138 (47 for deaths and 91 for injuries). The accident severity rate was high because the 4.6 casualties per one accident were occurred averagely although the incident rate was relatively low. Especially, one of form support members, the pipe supports have not been equipped adequately so that the accidents could have happened. In this regard, this study performed buckling test related to the effect of horizontal connection and slope in the single pipe which is one of typical pipe supports. The buckling load, which was estimated from the single pipe with the horizontal connectors theoretically and experimentally, was increased as more than 2 times compared to the buckling load obtained from the pipe supports without the connector. The buckling load was reduced as more than 26%, 34% slope of the single pipe comparing with 5% and 10% slope, respectively. Thus, the purpose of this study is to provide the guideline for installation and the maintenance of the pipe supports legally and institutionally to prevent the collapse accidents of the pipe supports.

• 한국농공학회논문집
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• 제52권2호
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• pp.59-66
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• 2010

This study was performed to develop the embankment protection method that can reduce demage by prevention of embankment loss and collapse from overflow due to heavy rain and flood. For overflow test, model dam was prepared and embankment behaviors were monitored with the established piezometer and strain meter during overflow. As a result of overflow test for model dam, in case of embankment without waterproof mat, the lower end of embankment was collapsed within 40 seconds after beginning of overflow. On the other hand, in case of embankment with waterproof mat, embankment collapse didn't occurred during overflow. Accordingly, establishment of waterproof mat for embankment showed that be absolutely effective for the embankment protection during overflow in reservoir. Also, it showed that the minimum establishment range of waterproof mat to prevent embankment collapse in reservoir is from maximum storage level to the lower end of embankment.

• 한국해양공학회지
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• 제34권1호
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• pp.37-45
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• 2020

Unstiffened and stiffened cylindrically curved plates are often used in ship structures. For example, they can be found on a deck with a camber, a side shell at the fore and aft parts, and the circular bilge part of a ship structure. It is believed that such cylindrically curved plates can be fundamentally modelled using a portion of a circular cylinder. From estimations using cylindrically curved plate models, it is known that the curvature generally increases the buckling strength compared to a flat plate under axial compression. The existence of curvature is also expected to increase both the ultimate and buckling strengths. In the present study, a series of finite element analyses were conducted on stiffened curved plates with several varying parameters such as the curvature, panel slenderness ratio, and web height and type of stiffener applied. The results of numerical calculations on stiffened and unstiffened curved plates were examined to clarify the influences of such parameters on the characteristics of their buckling/plastic collapse behavior and strength under an axial compression.