• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.91-104
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• 2008

In tunnels, safety factor concept has been suggested to estimate their stability quantitatively. It is merely limited in the framework of mechanical analysis. However safety factor concept has not been applied in hydro-mechanical coupled analyses due to their modelling complexity. Recently studies on this topic are being actively made. In this study, induced drainage modelling methods for hydro-mechanical coupled analyses are compared and analyzed to estimate safety factor of a subsea tunnel exactly. To this end, methods both controlling hydraulic characteristic of shotcrete and using a drainage well are considered. Sensitivity analysis were carried out on rock class, thickness of shotcrete, and hydraulic properties of rock mass. As the results of this study, it turned out that the induced drainage modelling using a drainage well would give more reliable results than that of controlling hydraulic characteristic of shotcrete in estimating tunnel stability in hydro-mechanical coupled analyses.

• Journal of Korea Water Resources Association
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• v.40 no.2 s.175
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• pp.125-134
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• 2007

The objective of this study was to investigate the applicability of new vegetation revetment techniques. The applicability of revetments was confirmed with respect to flood safety as well as environmental consideration. The safety against flood was examined through an in situ experiment at Dong-moon Stream located in Paju and a laboratory experiment. The environment-friendly characteristics of revetments were analyzed by using the results of a 2-year in situ monitoring. It was found that the revetments investigated in this study had a safety capability against floods and high vegetating capability. Application ranges of design factors were suggested for each revetment developed in this study.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.2
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• pp.46-56
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• 2000

This paper is related with one of safety plans to rescue a damaged-ship whether by collision, grounding or internal accident. We discuss the problem on course stability of damaged-ship while towed under severe wind pressure. The characteristic equation to assess the stability on course, is derived from sway and yaw coupled motion of towing and towed vessels with wind effect. Through the numerical calculation on course stability of towing and towed vessels system, the relationship between the course stability of a towed damaged-ship and wind direction or towrope length, is clarified with the parameters of weather and damage conditions.

• Proceedings of the Korean System Dynamics Society
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• 2001.10a
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• pp.67-79
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• 2001

발전원별 경쟁(신규 발전소 건설이 시장 가격에 의해 결정)을 도입한 미국의 캘리포니아주에서는 최근 심각한 전력 공급문제가 발생하였다. 미국과 같은 발전원별 경쟁을 도입한 우리나라의 경우에도 전력시장에서의 시장가격을 예측하고 이에 따른 신규 발전소 건설을 예측하여 전력 공급의 안전성을 검토할 필요가 있으며 또한 원자력이나 유연탄의 공급이 이러한 전력 공급의 안정성에 어떻게 기여할 수 있는가를 검토하는 것은 의의 있는 일이다.(중략)

• Tunnel and Underground Space
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• v.10 no.2
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• pp.237-248
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• 2000

Based on the preliminary results from the therm analysis, which is currently carrying, three-dimensional computer simulations using a finite element code, ABAQUS Ver. 5.8, were designed to determine the mechanically stable cavern and deposition hole spacing. Linear elastic modeling for the cases with different cavern and deposition hole spacing were carried out under three different in situ stress conditions. From the simulations, the response of the rock to the stress redistribution after the excavation of the openings could be investigated. Also the optimum cavern and deposition hole spacing could be estimated based on the factor of safety. When the in situ stress determined from the actual stress measurements in Korea were used, the case with cavern spacing of 40m and deposition hole spacing of 3m was in very stable condition, because the factor of safety was calculated as 3.42., When the in situ stress conditions for Sweden and Canada were used, the previous case, they seem to be in stable condition, since the factors of safety are still higher than 1.0. From these results, it was concluded that the rock will not fail even after the stress redistribution.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.11-16
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• 2020

The rotational stability of an interlocking caisson breakwater was studied. Using the analytical solution for the linear wave incident to the infinite breakwater, the phase difference effect of wave pressures in the direction of the breakwater baseline is considered, and Goda's wave pressure formula in the design code is adopted to consider the nonlinearity of the design wave. The rotational safety factor of the breakwater was defined as the ratio of the rotational frictional resistance moment due to caisson's own weight and the acting rotational moment due to the horizontal and vertical wave forces. An analytical solution for the rotational center point location and the minimum safety factor is presented. Stability assessment formula were proposed to be applicable to all design wave conditions used in current port and harbor structure design such as regular waves, irregular waves and multi-directional irregular waves.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.387-401
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• 2007

Recently, because of the restriction of land for construction and interference of adjacent structure, parallel tunnels with small clearance have been planned and constructed in many sites. In this case, the stability of pillar at center part is very important factor to satisfy the stability of tunnel structure under the construction. In this paper, numerical analyses for the asymmetry parallel tunnels with a narrow width of pillar have been carried out to search for the optimum reinforcement measure for rock pillar and verify the stability of tunnel. Rock pillar between each single tunnel is supposed to be under heavy load by rock mass. The analysis of stress state at rock pillar at various cases for construction conditions is required to investigate the structural behaviour of tunnels and stability of the pillar. Strength-stress ratio is calculated based on the failure theory of rock and the safety factor of tunnel is computed with strength reduction technique. Through these numerical results, reasonable reinforcement measures for rock pillar at parallel tunnel were established and recommended.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.87-94
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• 1997

There are many kinds of complicated equipments in the chemical plants. So the chemical plants have high possibility of accidents. Hazard analysis is one of the basic tasks to ensure the safety of chemical plants. However, it has many shortcomings. To overcome the problems, there have been attempts to automate this work by utilizing computer technology, particularly knowledge-based technique. However, many of the past approaches are lacking in properties: safeguard consideration, accident diversity, cause and consequence diversity, pathway leading to accidents, and various hazard analysis reasoning. Therefore, in this study, three analysis algorithms were proposed using multimodel approach, and a hazard analysis system, AHA, was developed on G2. The case study was solved with AHA system successfully.

• The Safety technology
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• no.177
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• pp.18-19
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• 2012

지난해 발생한 동일본 대지진은 지구촌 모든 이들에게 엄청난 충격을 줬다. 지진과 쓰나미 등 자연재해의 무서움을 충분히 실감케 한 것이다. 특히 후쿠시마 원전 사고는 당사국인 일본은 물론 전 세계에 방사능 누출에 대한 두려움을 확산시켰다. 원자력 발전소를 운영하고 있는 각국들이 원전의 안전을 위해 더욱 심혈을 기울이게 된 것이다. 사실 원자력 발전소에서 방사능이 누출되면 그 피해는 주변지역은 물론 해당 국가, 더 나아가 전 세계적으로 엄청난 영향을 미치기 된다. 때문에 원자력 발전소에서는 경제논리가 절대로 안전 논리보다 우선시될 수 없는 것이다. 그렇다면 원전의 안전성은 어떻게 확보되고 있을까. 이와 관련된 업무를 맡고 있는 이가 바로 오늘 소개할 지문구 한국수력원자력 중앙연구원 계통신뢰도기술팀장이다. 그는 팀원들과 함께 설비의 신뢰성을 바탕으로 원자력 발전소의 안전성을 정량적으로 판단하는 한편 안전성을 확보하는 방안에 대해 다양한 연구를 하고 있다. 또한, 안정적인 전력 생산을 위한 연구에도 매진하고 있다. 이와 같은 그의 활동이 어떻게 원자력 발전소 안전에 큰 버팀목으로 작용하고 있는지 살펴봤다.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.519-526
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• 2000

강수량 변동에 따른 사면 내의 지하수유동과 사면의 안정성 변화를 동시에 분석.평가하기 위하여 하나의 완전 연동된 수리지질역학적 모델을 제시하였다. 이 모델은 변형성 지질매체 내에서의 지하수유동을 설명하는 일련의 지배식들과 Galerkin 유한요소법에 기초하여 개발되었다. 1990년부터 1999년까지의 서울지역의 건기 (1월) 및 우기 (8월) 강수량 하에 있는 토양 사면에 대해 개발된 모델을 적용하여 일련의 수치실험을 실시하였다. 수치실험의 결과는 강수량이 증가함에 따라 사면의 수리역학적 안정성이 전반적으로 악화됨을 보여준다. 즉 강수량이 증가할수록 공극수압이 증가하고 지하수면이 상승한다. 그 결과 불포화대가 축소되고 삼출면이 팽창되며 사면의 전단부를 따라 지하수유동속도가 증가하게 된다. 동시에 강수량이 증가할수록 사면 전단부를 향해 전반적인 변위량이 증가한다. 그 결과 안전율이 1 이하인 불안전한 지역이 사면 전단부에서 사면 상부 쪽으로 전파.팽창되며 그 두께도 증가한다. 수치실험의 결과는 또한 사면의 표면에서는 전단파괴와 더불어 인장파괴도 발생할 수 있음을 보여준다.