• Bulletin of the Society of Naval Architects of Korea
• /
• v.37 no.3
• /
• pp.32-46
• /
• 2000

본고에서는 1912년 타이타닉호의 침몰사고 이후 도입된 구획 및 손상복원성규칙의 개정현황, 1987년 herald of Free Enterprise 호와 1994년 Estonia 호의 Ro-Ro Space 해수유입으로 인한 침몰사고 이후 도입된 잔존 복원력 요건 및 Ro-Ro Passenger Ship의 강화 규정을 요약하였다. 또한 IMO 혐약 내의 모든 손상복원성 류칙을 확률론적인 방법으로 통합하기 위하여 IMO SLF (복원성, 만재홀수선 및 어선안전 소위원회)에서 진행중인 HArmonization 작업과 이에 중대한 영향을 미칠 것으로 예상되는 EU(유럽연합) Consortium Project 인 "Harmonization of Rules and Design Rationale(HARDER)" 에 대한 현재까지 의 동향을 요약하였다. 그리고, 부록으로서 방화 및 구명 설비에 대한 협약개정동향을 수록하였다.동향을 수록하였다.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.4
• /
• pp.89-102
• /
• 2004

The generated blasting pressure wave initiated under decoupled-charge condition is a function of peak blasting pressure, rise time, and wave-shape function. The peak blasting pressure and the rise time are also the function of explosive and rock properties. The probabilistic distributions of explosive and rock properties are derived from the results of their property tests. Since the probabilistic distributions of explosive and rock properties displayed a normal distribution, the peak blasting pressure and the rise time can also be regarded as a normal distribution. Parameter analysis and uncertainty analysis were performed to identify the most influential parameter that affects the peak blasting pressure and the rise time. Even though the explosive properties were found to be the most influential parameters on the peak blasting pressure and the rise time from the parameter analyses, the result of uncertainty analysis showed that rock properties constituted major uncertainties in estimating the peak blasting pressure and the rise time rather than explosive properties. Damage and overbreak of the remaining rock around the excavation line induced by blasting were evaluated by dynamic numerical analysis. A user-subroutine to estimate the rock damage was coded based on the continuum damage mechanics. This subroutine was linked to a commercial program called 'ABAQUS/Explicit'. The results of dynamic numerical analysis showed that the rock damages generated by the initiation of stopping hole were larger than those from the initiation of contour hole. Several methods to minimize those damages were proposed such as relocation of stopping hole, detailed subdivision of rock classification, and so on. It was found that fracture probability criteria and fractured zones could be distinctively identified by applying fuzzy-random probability.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.37 no.2
• /
• pp.119-131
• /
• 2024

Pulse-like ground motion can cause greater damage to structures than nonpulse-like ground motion. Currently, much research is being conducted to determine the presence or absence of velocity pulses and to quantify them from seismic-acceleration records. Existing ground motion is divided into far-field (FF) and near-fault ground motion, based on the distance of the measurement point from the fault. Near-fault ground motion is further classified into near-fault pulse-like (NFP) and near-fault nonpulse-like (NFNP) ground motion by quantifying the presence or absence of velocity pulses. For each ground motion group, 40 FF, 40 NFP, and 40 NFNP ground motions are selected; thus, 120 ground motions are used in the seismic analysis to assess the seismic fragility of sample bridges. Probabilistic seismic demand models (PSDMs) are created by evaluating the seismic responses of two types of sample bridges with lead-rubber and elastomeric rubber bearings using three groups of ground motions. Seismic fragility analysis is performed using the PSDM, and from these results, the effect of the presence or absence of seismic velocity pulses on the seismic fragility is evaluated. From the comparison results of the seismic fragility curve, the seismic fragility of NFP ground motion appears to be approximately three to five times greater than that of NFNP ground motion, according to the presence or absence of a velocity pulse of seismic waves. This means that the damage to the bridge is greater in the case of NFP ground motion than that in the case of NFNP ground motion.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.2
• /
• pp.143-159
• /
• 2017

A probabilistic fragility assessment procedure is developed in this paper to predict risks of damage arising from seismic loading to the two-cell RC box tunnel. Especially, the paper focuses on establishing a simplified methodology to derive fragility curves which are an indispensable ingredient of seismic fragility assessment. In consideration of soil-structure interaction (SSI) effect, the ground response acceleration method for buried structure (GRAMBS) is used in the proposed approach to estimate the dynamic response behavior of the structures. In addition, the damage states of tunnels are identified by conducting the pushover analyses and Latin Hypercube sampling (LHS) technique is employed to consider the uncertainties associated with design variables. To illustrate the concepts described, a numerical analysis is conducted and fragility curves are developed for a large set of artificially generated ground motions satisfying a design spectrum. The seismic fragility curves are represented by two-parameter lognormal distribution function and its two parameters, namely the median and log-standard deviation, are estimated using the maximum likelihood estimates (MLE) method.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.3
• /
• pp.31-41
• /
• 1988

Recently, the offshore structures are increasingly constructed to explore the natural resources. These offshore structures are to be designed to resist the repetitive wave forces. A probabilistic method for the fatigue analysis of offshore concrete structures is presented in this study. The present spectral fatigue analysis calculates wave forces first and then the transfer functions for unit waves from which stress spectra are determined. The calculated fatigue stresses may then be used to evaluate the fatigue damage of concrete structures. A simplified model for the estimation of fatigue damage of the structures, which employs only the probabilistic moments of the peak stress distribution without direct integration, is also proposed. The present study allows more realistic fatigue analysis of offshore concrete structures.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.2
• /
• pp.163-168
• /
• 2011

Robust optimization or reliability-based design optimization are some of the methodologies that are employed to take into account the uncertainties of a system at the design stage. For applying such methodologies to solve industrial problems, accurate and efficient methods for estimating statistical moments and failure probability are required, and further, the results of sensitivity analysis, which is needed for searching direction during the optimization process, should also be accurate. The aim of this study is to employ the function approximation moment method into the sensitivity analysis formulation, which is expressed as an integral form, to verify the accuracy of the sensitivity results, and to solve a typical problem of reliability-based design optimization. These results are compared with those of other moment methods, and the feasibility of the function approximation moment method is verified. The sensitivity analysis formula with integral form is the efficient formulation for evaluating sensitivity because any additional function calculation is not needed provided the failure probability or statistical moments are calculated.

• Proceedings of the Korean Information Science Society Conference
• /
• 1999.10c
• /
• pp.63-65
• /
• 1999

산업현장에서의 자동화를 구축하기 위한 핵심 요소는 생산 현장의 제어장치를 직접 제어하는 PLC(Programmable Logical Controller)로 구성된다. PLC를 이용하여 생산 현장의 자동화를 구축하는 기존의 방법론은 대부분의 경우에서 현장의 자동화 구축 기간이 길고 비용이 많이 든다. 또한 이미 구축된 시스템에서 정밀한 테스트를 할 경우, 잘못된 동작으로 인해 발생하는 실제 현장에 설치된 제어장치의 손상될 확률이 높아진다. 본 논문에서는 기본 방법론에서 언급되는 문제점들을 프로그램의 컴포넌트(요소)로 개발하고 개선된 방법론을 이용할 수 있는 프로그램 시뮬레이터를 설계 및 구현한다. 프로그램 시뮬레이터의 개발 효과는 기존 방법론의 문제점들을 해결함으로써 생산성을 높일 수 있고 생산 비용을 줄일 수 있다.

• Journal of Power System Engineering
• /
• v.14 no.6
• /
• pp.61-66
• /
• 2010

Engineering asset management (EAM) requires the accurate assessment of current and the prediction of future asset health condition. Suitable mathematical models that are capable of predicting time-to-failure and the probability of failure in future time are essential. In general reliability models, lifetime of component and system is estimated using failure time data. This paper deals with the reliability assessment of elevators using life of main components. Especially this work is concerned with the stochastic nature of life of elevator components. First, we investigate the Weibull statistical analysis of lifetime data for the components. The final goal is to establish the mathematical model for reliability assessment. This work provides more perspectives to future research in the fields of reliability and maintainability.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.83-93
• /
• 1998

The twin aims of the present study are to develop a PC program for the statistical analysis of the measured cohesion data and to suggest a probabilistic corrosion rate estimation model for longitudinal members of tanker structures. A data analysis for the corrosion rate statistics(i.e., mean, standard deviation) as a function of the corrosion parameters is established for various structural member categories/locations of interest. Development of the computer program is focused on possible operation together with future addition of more corrosion data as they become available. To investigate the influence of the corrosion protection scheme a series of the corrosion analysis varying the life of coating are carried out and several different corrosion models as a function of time are suggested depending on the coating life.

• Tunnel and Underground Space
• /
• v.24 no.3
• /
• pp.212-223
• /
• 2014

In this study, the stability analyses for metal mine roadways at a great depth were performed. In-situ stress measurements using hydrofracturing, numerous laboratory tests for rock cores and GSI & RMR classifications were conducted in order to find the physical properties of both intact rock and in-situ rock mass distributed in the studied metal mine. Through the scenario analysis and probabilistic assessment on the results of rock mass classification, the in-situ ground conditions of mine roadways were divided into the best, the average and the worst cases, respectively. The roadway stabilities corresponding to the respective conditions were assessed by way of the elasto-plastic analysis. In addition, the appropriate roadway shapes and the support patterns were examined through the numerical analyses considering the blast damaged zone around roadway. It was finally shown to be necessary to reduce the radius of roadway roof curvature and/or to install the crown reinforcement in order to enhance the stability of studied mine roadways.