• Geomechanics and Engineering
• /
• 제10권2호
• /
• pp.175-188
• /
• 2016

The construction of a new cavern modifies the state of stresses and displacements in a zone around the existing cavern. For multiple caverns, the size of this influence zone depends on the ground type, the in situ stress, the cavern span and shape, the width of the pillar separating the caverns, and the excavation sequence. Performances of underground twin caverns can be unsatisfactory as a result of either instability (collapse) or excessive displacements. These two distinct failures should be prevented in design. This study simulated the ultimate and serviceability performances of underground twin rock caverns of various sizes and shapes. The global factor of safety is used as the criterion for determining the ultimate limit state and the calculated maximum displacement around the cavern opening is adopted as the serviceability limit state criterion. Based on the results of a series of numerical simulations, simple regression models were developed for estimating the global factor of safety and the maximum displacement, respectively. It was proposed that a proper pillar width can be determined based on the threshold influence factor value. In addition, design charts with regard to the selection of the pillar width for underground twin rock caverns under similar ground conditions were also developed.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
• /
• pp.354-361
• /
• 2002

This paper propose section properties factor to generate stress history for fatigue analysis and safety inspection of steel bridge. A methodology is described for the computation of numerical stress histories in the steel truss bridge, caused by the vehicles using section properties factor. The global 3-D beam model of bridge is combined with the local shell model of selected details. Joint geometry is introduced by the local shell model. The global beam model takes the effects of joint rigidity and interaction of structural elements into account. Connection nodes in the global beam model correspond to the end cross-section centroids of the local shell model. Their displacements are interpreted as imposed deformations on the local shell model. The load cases fur the global model simulate the vertical unit force along the stringers. The load cases fer the local model are imposed unit deformations. Combining these, and applying vehicle loads, numerical stress histories are obtained. The method is illustrated by test load results of an existing bridge.

• 대한안전경영과학회지
• /
• 제16권4호
• /
• pp.295-303
• /
• 2014

In this paper, due to the instability of the domestic market, global competition is intensifying in the current situation of global capacity building of SMEs for the purpose of developing a diagnostic indicator placed on the purpose. In this model, the results of applying several companies overall global innovation pilot enterprises and non-rated global innovative companies awarded significant difference between the score and the ability to believe the show. Non-global innovation companies, the relative firm size factor and R&D investment and patent number of factors are lacking appeared shone This is a common small business nature of the majority of companies small and R&D investment, the absolute amount is insufficient to reflect that, but the global innovator in the case of firm size and the relatively large amount of investment that never shows.

• 한국안전학회지
• /
• 제34권1호
• /
• pp.62-69
• /
• 2019

Korean shipbuilding companies have taken many efforts for safety over the years by developing Health, Safety & Environment (HSE) Management Systems, Procedures, Training, and studying Programs for prevention of incidents. As a result, the shipbuilding industry has succeeded in reducing overall injury rates. Nevertheless, the industry also noticed that incident rates are still not at zero and more importantly, serious injuries and fatalities are still occurring. One factor that may be attributing to this is the lack of managing potential severity during incident investigations, most incident investigations are implemented based on the actual result. Generally, each shipbuilding company develops their customized incident investigation programs and these are also commonly being focused on actual result. This study aimed to develop a shift in strategy toward safety to classify the criteria of potential severity from any incidents and manage that to prevent any recurrence or causing any serious injuries or fatalities in the shipbuilding industry. Several global energy companies have already developed potential severity management tools and applied them in their incident investigations. In order to verify the necessity of improvement for current systems, a case study and comparative analysis between a domestic shipbuilding company and several global energy companies from foreign countries was implemented and comparison of two incident investigation cases from specific offshore projects was conducted to measure the value of a potential severity system. Also, a checklist was established from the data of fatalities and serious injuries in recent 5 years that occurred in Korea shipbuilding industry and a proposal to verify high potential incidents in the incident investigation process and comparative analysis between the assessment by appling proposed checklist and the assessment from a global energy company by using their own system was implemented. As a measure to prevent any incidents, it is required to focus on potential severity assessment during the incident investigation rather than to only control actual result. Hence, this study aims to propose a realistic plan which enables to improve the existing practices of incident investigation and control in the shipbuilding industry.

• 한국기계기술학회지
• /
• 제20권6호
• /
• pp.947-956
• /
• 2018

This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.176-183
• /
• 2008

This paper highlights the importance of carrying out global slope stability analysis as part of design calculations for geosynethetic walls in tiered configuration. Four design case histories were selected to examine the appropriateness of their design by performing additional slope stability analyses using the shear strength reduction method with in the frame work of finite element analysis. The results indicated that all of the walls examined, which were designed to meet the current design guide lines, did not satisfy the global slope stability requirement, and that longer reinforcements are required in the upper tiers to achieve the minimum factor of safety. Practical implications of the findings are discussed.

• Steel and Composite Structures
• /
• 제49권1호
• /
• pp.47-64
• /
• 2023

Due to their efficient use of materials, hybrid reinforced concrete-steel (RCS) systems provide more practical and economic advantages than traditional steel and concrete moment frames. This study evaluated the seismic design factors and response modification factor 'R' of RCS composite moment frames composed of reinforced concrete (RC) columns and steel (S) beams. The current International Building Code (IBC) and ASCE/SEI 7-05 classify RCS systems as special moment frames and provide an R factor of 8 for these systems. In this study, seismic design parameters were initially quantified for this structural system using an R factor of 8 based on the global methodology provided in FEMA P695. For analyses, multi-story (3, 5, 10, and 15) and multi-span (3 and 5) archetypes were used to conduct nonlinear static pushover analysis and incremental dynamic analysis (IDA) under near-field and far-field ground motions. The analyses were performed using the OpenSees software. The procedure was reiterated with a larger R factor of 9. Results of the performance evaluation of the investigated archetypes demonstrated that an R factor of 9 achieved the safety margin against collapse outlined by FEMA P695 and can be used for the design of RCS systems.

• 한국지반공학회논문집
• /
• 제16권1호
• /
• pp.51-64
• /
• 2000

본 연구는 강우의 침투로 인한 불포화 토사사면의 안정 해석을 위한 절차를 제시한다. 강우 침투로 인한 사면의 거동은 흐름과 변형이 연관된 이차원 유한요소해석을 통하여 해석된다. 시간에 따른 안전율을 계산하기 위하여 유한요소 해석법을 통한 응력장(stress field)으로부터 가상활동면에 대한 안전율을 산정할 수 있도록 하는 정교한 응력적분기법을 적용하였고 기하학적으로 허용가능한 활동단면의 형상을 유지하면서 합리적으로 임계단면을 찾아가는 최적화방법을 적용함으로써 강우에 의한 토사사면의 안정성 평가 절차를 개발하였다. 또한 이를 이용하여 강우침투시 투수계수의 공간적인 변화가 불포화토사사면의 파괴 거동에 미치는 영향을 보다 공학적이고 합리적인 방법으로 연구하였다. 연구결과에 의하면 투수계수의 불균질한 분포로 인하여 강우에 의한 사면표면의 국부적인 파괴영역이 발생할 수 있고 이러한 영역이 점점 확대되어 전체적인 파괴에 이르게 된다. 그러므로 시간의존적 인 사면안정해석 문제의 경우 이러한 국부적인 파괴 영역의 영향을 더 이상 무시할 수 없다.

• 한국지반공학회논문집
• /
• 제15권3호
• /
• pp.27-40
• /
• 1999

사면안정해석을 수행하기 위하여 많이 사용하는 한계평형방법은 일정한 가정을 하여 안전율을 평형에 필요한 응력과 흙의 전단강도의 비로 정의하여 대상사면의 안전율을 구한다. 유한요소법을 이용한 사면안정해석방법은 응력상태를 유한요소법으로 구한 후 원호나 대수나선형등의 일정한 모양의 사면 파괴선을 가정하여 반복적으로 최소안전율을 구한다. 본 연구에서는 유한요소법을 이용한 사면안정해석방법을 개발하여 사면의 가장 취약한 부분을 따라 파괴선이 발생하도록 하였다. 이것은 요소내의 국부안전율과 파괴각을 고려하여 사면파괴선을 자동적으로 구할 수 있도록 함으로써 가능한데 이 방법은 임의의 파괴선을 가정할 필요가 없으며 절편에 작용하는 힘에 대하여 가정을 할 필요가 없고 임의의 모양의 파괴선을 구할 수 있는 장점이 있다. 본 연구에서는 개발된 해석방법을 검증하기 위하여 가상의 사면, 자연사면, 그리고 댐사면에 적용하여 실무에서 많이 사용하는 한계평형방법 프로그램인 STABL5M과 SLOPE/W과 비교 평가하였다.

• 무역학회지
• /
• 제45권1호
• /
• pp.259-277
• /
• 2020

The purpose of this study is to analyze the relationship between logistics safety climate, logistics safety behavior, and logistics safety performance and the mediating effects of safety knowledge and safety motivation, and to suggest its strategic implications for the improvement of the logistics safety performance. Based on previous researches related to logistics safety, safety climate, safety knowledge, safety motivation, safety behavior and safety performance, research models and hypotheses were set up and questionnaires were conducted. For the hypothesis test, reliability analysis and validity analysis, confirmatory factor analysis, structural equation model analysis, and bootstrapping were applied. As a result of the empirical analysis, the logistics safety climate had a significant positive effect on logistics safety knowledge, logistics safety motivation, and logistics safety behavior, whereas logistics safety knowledge and logistics safety motivation had a meaningful positive effect on logistics safety behavior. Further, logistics safety behavior was found to have a significant positive effect on logistics safety performance. Safety behavior had a significant mediating effect, but safety knowledge and safety motivation did not. However, logistics safety climate, logistics safety knowledge, and logistics safety motivation did not have a significant effect on logistics safety performance.