• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.127-134
• /
• 2021

When constructing a tunnel on a stable ground, stress is changed in the ground during excavation stage and installation of ground support materials. In the standards for safety evaluation of structures in use, it is suggested to perform numerical analysis reflecting the excavation stage. But method of seismic performance evaluation was not presented. Therefore, in this study, numerical analysis was performed with different analysis methods, and the results were compared and analyzed. As a result of the numerical analysis, seismic wave applied in the horizontal direction were no difference depending on the analysis methods. However, there was a big difference in the result according to the evaluation methods of tunnel member forces. When reviewing with the strength design method, the structure performance could be not satisfied depending on the existence or nonexistence of reinforcing bars. Based on these research results, it is suggested that the interpretation method should be clearly presented and reflected in the relevant standards.

• Journal of the KSME
• /
• v.16 no.2
• /
• pp.6-14
• /
• 1976

원자로의 안전성확보의 기본은 원자로의 운전에 의한여 발새하는 방사성 물질을 확실하게 관리하 여 방사서의 해로부터 공중의 건강과 안전을 보존하는 것이다. 원자로에는 로내의 방사성물질인 핵분열생성물의 누설을 방지하는 일련의 독립적 방벽들 즉 연료의 피복제, 원자로용기를 포함하 는 일차냉각재계용, 그리고 일차냉각재계통을 수용하는 격납용기들로 된 다중방호벽이 마련되어 있다. 원자로설계기준에서는 이들 방호벽이 어떠한 가상적사고가 발생하여도 그 건전성이 유지되 도록 요구하고 있디. 우리나라에서도 미국의 기준을 준용하는 원칙으로 고리 원자력발전소 등 1 호기에 대한 해석이 수행되었던 것이다. 여기서 해석판정기준 및 해석결과를 소개하고저 하는 것이다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.3A
• /
• pp.181-188
• /
• 2009

This study presented the basic data for determining reasonable construction method and evaluating the structural safety of suspension bridges. The analytical program was developed to conduct initial shape and natural frequency analysis, construction stage analysis and reliability analysis considering construction sequences. This program was based on analysis models of suspension bridges and reliability theories used in the previous study. A construction method was established considering various construction variables such as construction order and construction direction of girder and synchronized construction of main and side span etc. The dynamic construction analysis by a construction scheme was conducted with the developed program. Benefits of the characteristic analysis by the construction scheme was presented estimating structural response of critical members respectively. Structural reliability analysis by construction stage was conducted considering aleatory uncertainties. The safety of suspension bridges by established construction method was quantitatively estimated using reliability index and failure probability. Analytical results were re-estimated considering epistemic uncertainties, and critical percentile distributions of risk at the construction stage were presented using the frequency histogram.

• Computational Structural Engineering
• /
• v.2 no.4
• /
• pp.89-98
• /
• 1989

In order to take account of the statistical properties of random variables used in the structural analysis, the conventional approach usually adopts the safety factor based on past experiences for the qualitative assessment of structural safety problem. Recently, new approach based on the probabilistic concept has been applied to the assessment of structural safety in order to circumvent the difficulties of the conventional approach in choosing the appropriate safety factor. Thus, computer program called "Probabilistic finite element method" is developed by incorporating the probabilistic concept into the conventional matrix method in order to investigate the effects of the random variables on the final output of the structural analysis. From the comparison of some examples, it can be concluded that the PFEM developed in this study deals consistently with the uncertainty of random variables and provides the rational tool for the assessment of structural safety of plane frame.

• Proceeding of EDISON Challenge
• /
• 2017.03a
• /
• pp.358-364
• /
• 2017

많은 공사 현장에는 개구부, 작업발판, 가설계단의 통로 등에서의 추락사고를 방지하기 위해 설치하는 가시설물 중 안전난간이 있다. 안전난간은 작업장에서 현장인부들의 생명과 직결되므로 반드시 적절한 기준에 맞춰 설계를 하는 것이 필요하다. 이러한 안전난간은 표준안전난간으로서 추락재해방지 표준안전작업지침[1]에 의해 설계 기준이 명확하게 명시되어 있으며 난간대와 기둥각 부분 접합부는 쉽게 변형, 변위를 일으키지 않는 구조를 가져야 한다. 본 연구에서는 지침에 지시된 표준안전난간을 실제 설계기준에 맞게 직접 구조물을 모델링하고 EDISON용 구조해석 프로그램인 CASADsovler를 통해 유한 요소 해석을 수행하여 안전난간에 가해지는 응력 및 변위 결과들을 통해 구조의 안정성을 시험해 보았다. 더하여 다구찌 기법과 최적설계에 기반하여 안전난간 무게의 경량 최적화를 위한 연구를 진행하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.14 no.2
• /
• pp.95-107
• /
• 2002

A reliability analysis on sliding of monolithic vertical caisson of composite breakwaters is extensively carried out in order to make the basis for the applicability of reliability-based design method. The required width of caisson of composite breakwaters is determined by the deterministic design method including the effect of impulsive breaking waves as a function of water depth, also studied interactively with the results of reliability analyses. It is found that the safety factor applied in current design may be a little over-weighted magnitude for the sliding of caisson. The reliability index/failure probability is also seen to slowly decrease as the water depth increases for a given wave condition and a safety factor. In addition, optimal safety factor can roughly be evaluated by using the concept of target reliability index for several incident waves. The variations of optimal safety factor may be resulted from the different wave conditions. Finally, it may be concluded from the sensitivity studies that the reliability index may be more depended on the incident wave angles and the wave periodsrather than on the bottom slopes and the thickness of rubble mound.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.5
• /
• pp.437-446
• /
• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05b
• /
• pp.870-876
• /
• 1998

원자로용기의 안전성은 가동중 운전조건과 조사취화등으로 인한 재료의 열화(degradation)를 검토함으로써 평가되는데, 특히 운전조건중, 비상사태에 해당하는 가압열충격에 관한 평가가 최근 중요한 안전문제로 부각되고 있다 본 연구의 목적은 가압열충격 사고중 소규모 냉각재 손실사고(Small LOCA)가 발생하는 경우, 원자로용기 내벽에 존재하는 균열의 안전성을 유한요소해석을 통해 평가하는 것이다. 본 연구에서는 Small LOCA 발생시 원자로용기의 내벽에 존재하는 균열의 종류, 방향, 균열형상비 및 클래드부의 두께가 응력확대 계수 계산에 미치는 영향을 평가하였으며, 이를 위해 총 14가지 경우에 대해서 3차원 유한요소해석을 수행하였다. 이러한 Small LOCA 해석수행을 기초로 다양한 가압열충격 사고에 대한 유한요소해석 모델링 기법, 해석 기법, 후처리 기법을 제시하였다.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.1
• /
• pp.47-55
• /
• 2008

Recently, it has been reported that buried pipes' crack is concentrated on curved parts. In this study, 3D-Finite element analysis is performed for Analytical Evaluation on the Structural Safety of Horizontally Curved Parts of Buried Pipe. The constructed pipe cracked in curved parts of pipe is analyzed and all kinds of loads affected to buried pipes are considered. Displacement, stresses and buckling analysis are performed. The stress analysis shows that stress in curved parts is larger than stresses in straight parts and exceeds allowable stress in some parts. So, stress analysis on curved parts is needed for safety for buried pipe.

• Proceedings of the Korean Society of Disaster Information Conference
• /
• 2023.11a
• /
• pp.105-106
• /
• 2023

본연구는 콘크리트 타설과정에서 반복되는 펌프카 사고를 예방하기 위해서 설계 및 제작의 품질관리와 현(現))정기검사 기준을 개선해야 한다는 점을 제안하며, Booms 파단 사고 예방대책 제시가 목적이고, 최근 1~2년 사이에 발생한 펌프카 기계적 결함 사고의 현황조사와 사고 특징을 분석하고, 펌프카 장비의 검사기준 및 조정원의 자격과 기능교육 기준 마련의 필요성 확인한다. 붐대의 안전성 확인하기 위해서는 선행연구의 구조적 안전성 평가와 최대응력 부위에 대한 선행연구의 유한요소 해석모델 자료를 재분석하고, 2단 붐이 타설중 가장 많은 힘을 받는지와 파괴 가능성을 확인한다. Booms의 유한요소 모델 해석 결과 펌프카는 타설 과정에서 진동으로 피로 하중을 받을 수 있다는 동적해석과 정적해석 재검토 결과 가장 취약한 부위는 2단 붐이었으며, 2st 붐은 제작단계에서 부재 두께를 증가시키고, 상단부에 철판 보강을 권장한다. 펌프카 사고를 방지하기 위해서는 제조사는 생산단계에서 2st Boom 상단에 보강판 부착이 필요하고, 정기검사 비용 현실화와 비파괴 검사를 의무 검사로 반영이 필요하다고 제언한다.