• Earthquakes and Structures
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• 제22권1호
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• pp.95-107
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• 2022

This paper introduces a novel, rigorous, and efficient probabilistic methodology for the performance-based optimal design (PBOD) of semi-active tuned mass damper (SATMD) for seismically excited nonlinear structures. The proposed methodology is consistent with the modern performance-based earthquake engineering framework and aims to design reliable control systems. To this end, an optimization problem has been defined which considers the parameters of control systems as design variables and minimization of the probability of exceeding a targeted structural performance level during the lifetime as an objective function with a constraint on the failure probability of stroke length damage state associated with mass damper mechanism. The effectiveness of the proposed methodology is illustrated through a numerical example of performance analysis of an eight-story nonlinear shear building frame with hysteretic bilinear behavior. The SATMD with variable stiffness and damping have been designed separately with different mass ratios. Their performance has been compared with that of uncontrolled structure and the structure controlled with passive TMD in terms of probabilistic demand curves, response hazard curves, fragility curves, and exceedance probability of performance levels during the lifetime. Numerical results show the effectiveness, simplicity, and reliability of the proposed PBOD method in designing SATMD with variable stiffness and damping for the nonlinear frames where they have reduced the exceedance probability of the structure up to 49% and 44%, respectively.

• Coupled systems mechanics
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• 제11권6호
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• pp.505-524
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• 2022

Floods represent extreme hydrological phenomena that affect populations, environment, social, political, and ecological systems. After the catastrophic floods that have hit Europe and the World in recent decades, the flood problem has become more current. At the EU level, a legal framework has been put in place with the entry into force of Directive 2007/60/EC on Flood Risk Assessment and Management (Flood Directive). Two years after the entry into force of the Floods Directive, Bosnia and Herzegovina (B&H), has adopted a Regulation on the types and content of water protection plans, which takes key steps and activities under the Floods Directive. The "Methodology for developing flood hazard and risk maps" (Methodology) was developed for the territory of Bosnia and Herzegovina, following the methodology used in the majority of EU member states, but with certain modifications to the country's characteristics. Accordingly, activities for the preparation of the Preliminary Flood Risk Assessment for each river basin district were completed in 2015 for the territory of Bosnia and Herzegovina. Activities on the production of hazard maps and flood risk maps are in progress. The results of probable climate change impact model forecasts should be included in the preparation of the Flood Risk Management Plans, which is the subsequent phase of implementing the Flood Directive. By the foregoing, the paper will give an example of the development of the hydrodynamic model of the Zujevina River, as well as the development of hazard and risk maps. Hazard and risk maps have been prepared for medium probability floods of 1/100 as well as for high probability floods of 1/20. The results of LiDAR (Light Detection and Ranging) recording were used to create a digital terrain model (DMR). It was noticed that there are big differences between the flood maps obtained by recording LiDAR techniques in relation to the previous flood maps obtained using georeferenced topographic maps. Particular attention is given to explaining the Methodology applied in Bosnia and Herzegovina.

• 보건행정학회지
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• 제14권2호
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• pp.78-98
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• 2004

The purpose of this study was to categorize the contribution evasion and develop the expected models for contribution arrears in National Health Care System. The modified logistic regression model in non-payments was used as logistic regression model based on the statistical method. By using this model, we arranged non-payment types and typical branches those are appeared by statistical technique. First fact, sex and age branches those are able to take a part in economy had effect mostly. Also they had difference in non-payment probability by existence of their incomes and property. Especially people who didn't have their own house and car were appeared in high non-payment probability, disease and reduction characteristic(rare diseases, reduction of seniors, handicaps, numbers of medical treatments) didn't effect much in probability. The reason for some characteristic of non-payment which is higher than the correct threshold value of Logistic Regression Model (a suggested model for predicting non-payment)'s distribution of probability was mostly moral hazard. Living difficulty was the bigger reason for non-payment, but moral slackening was the bigger reason for non-payment. But it is careless to decide that moral hazard is just the reason, there is a necessity to examine on the side of sociology based in family. By the reason, the member's non-payment reason can be classified by economy, population, and psychology, but there was a comprehension that losing of work desire could be one reason. So we analyzed informations for composition of family of members. In conclusion, we grasped that family conflict makes non-payment and conversion of member in the National Basic Livelihood Protection System difficult.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.485-494
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• 2016

The risk-based assessment, also called time-based assessment of structure is usually performed to provide seismic risk evaluation of a target structure for its entire life-cycle, e.g. 50 years. The prediction of collapse probability is the estimator in the risk-based assessment. While the risk-based assessment is the key in the performance-based earthquake engineering, its application is very limited because this evaluation method is very expensive in terms of simulation and computational efforts. So the evaluation database for many archetype structures usually serve as representative of the specific system. However, there is no such an assessment performed for building stocks in Korea. Consequently, the performance objective of current building code, KBC is not clear at least in a quantitative way. This shortcoming gives an unresolved issue to insurance industry, socio-economic impact, seismic safety policy in national and local governments. In this study, we evaluate the comprehensive seismic performance of an low-rise residential buildings with discontinuous structural walls, so called piloti-type structure which is commonly found in low-rise domestic building stocks. The collapse probability is obtained using the risk integral of a conditioned collapse capacity function and regression of current hazard curve. Based on this approach it is expected to provide a robust tool to seismic safety policy as well as seismic risk analysis such as Probable Maximum Loss (PML) commonly used in the insurance industry.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1171-1177
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• 2007

We consider estimation of the right-tail probability in a log-Laplace random variable, As we derive the density of ratio of two independent log-Laplace random variables, the k-th moment of the ratio is represented by a special mathematical function. and hence variance of the ratio can be represented by a psi-function.

• Nuclear Engineering and Technology
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• 제34권6호
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• pp.586-595
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• 2002

The Seismic probabilistic risk assessment (SPRA) or seismic margin assessment (SMA) have been used for the seismic safety evaluation of nuclear power plant structures and equipments. For the SPRA or SMA, the reference response spectrum should be defined. The site-specific median spectrum has been generally used for the seismic fragility analysis of structures and equipments in a Korean nuclear power plant Since the site-specific spectrum has been developed based on the peak ground motion parameter, the site-specific response spectrum does not represent the same probability of exceedance over the entire frequency range of interest. The uniform hazard spectrum is more appropriate to be used in seismic probabilistic risk assessment than the site- specific spectrum. A method for modifying the seismic fragility parameters that are calculated based on the site-specific median spectrum is described. This simple method was developed to incorporate the effects of the uniform hazard spectrum. The seismic fragility parameters of typical NPP components are modified using the uniform hazard spectrum. The modification factor is used to modify the original fragility parameters. An example uniform hazard spectrum is developed using the available seismic hazard data for the Korean nuclear power plant (NPP) site. This uniform hazard spectrum is used for the modification of fragility parameters.

• Earthquakes and Structures
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• 제13권4호
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• pp.421-427
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• 2017

Seismic safety evaluation of weir structure is significant considering the catastrophic economical consequence of operational disruption. In recent years, the seismic probabilistic risk assessment (SPRA) has been issued as a key area of research for the hydraulic system to mitigate and manage the risk. The aim of this paper is to assess the seismic probabilistic risk of weir structures employing the seismic hazard and the structural fragility in Korea. At the first stage, probabilistic seismic hazard analysis (PSHA) approach is performed to extract the hazard curve at the weir site using the seismic and geological data. Thereafter, the seismic fragility that defines the probability of structural collapse is evaluated by using the incremental dynamic analysis (IDA) method in accordance with the four different design limit states as failure identification criteria. Consequently, by combining the seismic hazard and fragility results, the seismic risk curves are developed that contain helpful information for risk management of hydraulic structures. The tensile stress of the mass concrete is found to be more vulnerable than other design criteria. The hazard deaggregation illustrates that moderate size and far source earthquakes are the most likely scenario for the site. In addition, the annual loss curves for two different hazard source models corresponding to design limit states are extracted.

• Journal of the Korean Data and Information Science Society
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• 제21권4호
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• pp.747-756
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• 2010

최근의 전 세계적인 경기 침체에 따라 산업계 전반에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 신용보증기금에 등록된 중소기업들의 자료에 대하여 생존 분석을 이용하여 생존율을 추정하였다. 또한 중소기업의 자산규모와 업종에 따라 건설업과 타 업종으로 구분하여 생존율에 관한 동향을 비교분석하였다. 이때 생존율은 생명표에 의해 구하였으며, 업종별 생존율의 차이는 로그순위 검정과 윌콕슨의 검정통계량을 사용하여 분석하였다. 실험 결과 중소기업의 자산규모가 10억 이상이 가장 높았으며, 1억 미만, 1억에서 10억 미만은 비슷한 생존율을 보였다. 업종별로는 도소매업과 서비스업이 경공업과 중공업, 건설업에 비하여 생존율이 높았으며 건설업의 경우 생존율이 가장 낮음을 알 수 있었다. 또한 대부분의 중소기업들은 시간이 지날수록 위험률이 상승하는 추세를 보였다.

• 지질공학
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• 제18권3호
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• pp.303-309
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• 2008

중요 석조문화재가 위치하고 있는 강원도 양양군 소재 진전사지 주변지역에 대한 사면재해 가능성을 예측하였다. 연구지역에 대한 현장조사, 실내시험, 지질 및 지형자료 분석을 통해 산사태에 유의한 영향요소를 평가하고 그 자료들을 예측모델에 적용하여 산사태예측도를 작성하였다. 그리고 산사태예측도에 의해 발생확률을 등급별로 분류함으로써 산사태로 인한 석조문화재의 피해가능성을 검토하였다. 산사태예측도에 의하면, 발생확률 70% 이상으로 산사태가 발생될 가능성이 높은 지역은 대상면적의 10.1%인 $3,489m^2$정도로 비교적 넓은 면적비율을 나타내었다. 피해영향권에 속한 높은 고도의 산사면에서 산사태가 발생할 경우 국보 제122호인 진전사지삼층석탑과 보물 제439호인 진전사지부도에 사태물질로 인한 피해가능성이 예상된다.

• 한국방재학회 논문집
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• 제9권6호
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• pp.143-151
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• 2009

최근의 극한 수문사상은 홍수, 가뭄과 같은 심각한 재해를 발생시킨다. 많은 연구자들은 불확실한 미래의 확률강우량 및 유출량의 예측을 위해 많은 노력을 하고 있다. 본 연구에서는 불확실성이 낮은 확률강우량의 산정을 위하여 매개변수 추정법을 평가하였다. 인천, 강릉, 광주, 부산, 추풍령 관측소를 연구 대상 관측소로 선정하여 자료를 수집하였고, ARMA모형을 이용하여 합성강우자료를 구축하였다. 본 연구에서는 극치강우사상에 적합한 것으로 알려진 Gumbel 분포와 GEV 분포모형에 대한 매개변수를 최우도법과 베이지안 추론방법을 사용하여 추정하였으며, Bootstrap 방법을 이용하여 확률강우량의 신뢰구간 길이를 추정하였다. 매개변수 추정 방법별 산정된 확률강우량의 신뢰구간 길이를 비교함으로서 불확실성이 낮은 확률강우량을 산정할 수 있는 매개변수 추정방법을 선정하였다.