• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.339-339
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• 2017

손상함수란 건물, 차량, 농작물 등과 같은 피해대상물에 재난강도에 따른 취약도(vulnerability)를 정량화한 함수로, 재난리스크 모델에서 널리 사용되는 개념이다. 홍수재난에서 손상함수는 일반적으로 피해지역에서 조사된 경험적 피해자료(empirical data)를 활용하거나, 표준화된 피해대상물에 대한 손상성을 전문가의 의견(expert opinion)을 참고하여 개발된다. 이때, 취약도를 설명하는 설명변수는 일반적으로 침수심(inundation depth)이 사용되며, 그에 따른 취약도는 손상률(percent damage)로서 상대함수 형태가 일반적이다. 본 연구는 주거건물(residential building)에 대한 손상함수 개발을 위해 자연재난 손해사정 경력자(8인)를 대상으로 표준화된 주거건물(단독주택, 아파트, 연립/다세대주택)에 대해 침수에 따른 건물 손상성을 조사하였다. 주거건물 손상성을 설명하는 최대범위는 건물내부 바닥고를 기준으로 침수심 3m까지이며, 침수심 변화에 따른 손상성을 건물신축 공종에 따라 질의하고 이를 종합하였다. 조사과정은 (1) 표준건물에 대한 정의, (2) 공종별 침수에 따른 손상여부 질의, (3) 공종별 최대 손상률 평가 및 주요 피해내역 토의, (4) 공종별 침수심에 따른 손상률 평가, (5) 결과종합의 단계로 진행되었고, 이를 통해 주거건물 유형에 따른 손상함수를 개발할 수 있었다. 본 연구에서 개발된 손상함수는 다양한 침수높이에서 주거건물에 대한 취약도를 설명하는 데 장점이 있으나, 그 결과는 향후 홍수피해지역을 대상으로 수집된 다양한 피해조사 결과와 비교하여 보완될 필요가 있다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.1-13
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• 2022

A weighted linear combination of seismic fragility models previously developed for cut-and-cover railway tunnels was presented and the appropriateness of the combined model was evaluated. The seismic fragility function is expressed in the form of a cumulative probability function of the lognormal distribution based on the peak ground acceleration. The model uncertainty can be reduced by combining models independently developed. Equal weight is applied to four models. The new seismic fragility function was developed for each damage level by determining the median and standard deviation, which are model metrics. Comparing fragility curves developed for other bored tunnels, cut-and-cover tunnels for high-speed railway system have a similar level of fragility. We postulated that this is due to the high seismic design standard for high-speed railway tunnel.

• Journal of the Korea Institute of Building Construction
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• v.19 no.6
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• pp.529-538
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• 2019

Typhoons can cause significant financial damage worldwide. For this reason, states, local governments and insurance companies attempt to quantify and mitigate the financial risks related to these natural disasters by developing a typhoon risk assessment model. As such, the importance of typhoon risk assessment models is increasing, and it is also important to reflect local vulnerabilities to enable sophisticated assessments. Although a practical study of economic losses associated with natural disasters has identified essential risk indicators, comprehensive studies covering the correlation between vulnerability and economic loss are still needed. The purpose of this study is to identify typhoon damage indicators and to develop evaluation indicators for typhoon damage prediction functions, utilizing the loses from Typhoon Maemi as data. This study analyzes actual loss records of Typhoon Maemi provided by local insurance companies to prepare for a scenario of maximum losses. To create a vulnerability function, the authors used the wind speed and distance from the coast and the total value of property, construction type, floors, and underground floor indicators. The results and metrics of this study provide practical guidelines for government agencies and insurance companies in developing vulnerability functions that reflect the actual financial losses and regional vulnerabilities of buildings.

• Convergence Security Journal
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• v.4 no.2
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• pp.27-34
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• 2004

The recent explosive use of the Internet and the development of computer communication technologies reveal serious computer security problem. Inspite of many studies on secure access to the system, generally, the attackers do not use the previous intrusion techniques or network flaw, rather they tend to use the vulnerabilities residing inside the program, which are the running programs on the system or the processes for the service. Therefore, the security managers must focus on updating the programs with lots of time and efforts. Developers also need to patch continuously to update the Program, which is a lot of burden for them. In order to solve the problem, we need to understand the vulnerabilities in the program, which has been studied for some time. And also we need to analyze the functions that contains some vulnerabilities inside. In this paper, we first analyzed the vulnerabilities of the standard C library, and Win32 API functions used in various programs. And then we described the design and implementation of the automated scanning tool for writing secure source code based on the analysis.

• Economic and Environmental Geology
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• v.50 no.3
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• pp.195-214
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• 2017

Statistical landslide susceptibility analysis, which is widely used among various landslide susceptibility analysis approaches, predicts the unstable area by analyzing statistical relationship between landslide occurrence locations and landslide controlling factors. However, uncertainties are involved in the procedures of the susceptibility analysis and therefore, fuzzy approach has been used to deal properly with uncertainties. The fuzzy approach used fuzzy set theory and fuzzy membership function to quantify uncertainties involved in landslide controlling factors. Various fuzzy approaches were suggested in the procedure of the membership value determination and fuzzy operation in the previous researches. However, few studies were carried out to compare the analysis results obtained from various approaches for membership function determination and fuzzy operation. Therefore, in this study, the authors selected Jinbu area, which a large number of landslides were occurred at in 2006, to apply two most commonly used methods, the frequency ratio and the cosine amplitude method to derive membership values for each controlling factor. In addition, the integration of different thematic layers to produce landslide susceptibility map was performed by several fuzzy operators such as AND, OR, algebraic product, algebraic sum and Gamma operator. The results of the landslide susceptibility analysis using two different methods for the determination of fuzzy membership values and various fuzzy operators were compared on the basis of ROC graph to check the feasibility of the fuzzy based landslide susceptibility analysis.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.3-8
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• 2004

The majority of recent intrusions reveal that the attackers do not use the previous intrusion techniques or network flaw, rather they tend to use the vulnerabilities residing inside the program, which are the running programs on the system or the processes for the service. Therefore, the security managers must focus on updating the programs with lots of time and efforts. Developers also need to patch continuously to update the program, which is a lot of burden for them. In order to solve the problem, we need to understand the vulnerabilities in the program, which has been studied for some time. And also we need to analyze the functions that contains some vulnerabilities inside. In this paper, we first analyzed the vulnerabilities of the standard C library, and Win32 API functions used in various programs. And then we described the design and implementation of the automated scanning tool for writing secure source code based on the analysis.

• Journal of the Korean Geotechnical Society
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• v.39 no.5
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• pp.13-26
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• 2023

This study examined the soil-water characteristic curve (SWCC), considering the volume change, using wetting curves on the field monitoring data of a wireless sensor network. Special attention was given to evaluating the landslide vulnerability by deriving a matric suction suitable for the actual site during the wetting process. Laboratory drying SWCC and shrinkage laboratory tests were used to perform the combined analysis of landslide and debris flow. The results showed that the safety factor of the wetting curve, considering the volume change of soil, was lower than that of the drying curve. As a result of numerical analyses of the debris flow simulation, more debris flow occurred in the wetting curve than in the drying curve. It was also found that the landslide analysis with the drying curve tends to overestimate the actual safety factor with the in situ wetting curve. Finally, it is confirmed that calculating the matric suction through SWCC considering the volume change is more appropriate and reasonable for the field landslide analysis.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.274-280
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• 2018

This paper deals with the calculation of vulnerable areas of critical components required for the assessment of naval ship's vulnerability. Taking into account the effectiveness of threatening weapons, the probability density function of damage was used to assess vulnerable areas or vulnerabilities of critical components. It is shown that the vulnerable area of critical component can be simply computed from the damage function. Considering the weapon effectiveness of fragmentation and explosion on the target, both Carleton Damage Function and Rectangular Cookie Cutter Function representing the probability of damage are applied to the vulnerable area assessment. Carleton damage function is utilized to describe the weapon-target interaction in the vulnerability analyses. A problem of blast effect against an assumed naval ship is chosen as a case study. Vulnerability is evaluated by applying the suggested method to the equipments arranged in the engine room of the virtual ship.

• Journal of the Korean earth science society
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• v.34 no.6
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• pp.524-535
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• 2013

Catastrophe risk models require the damage functions of each vulnerable item in inventory to estimate volcanic ash losses. The damage functions are used to represent the relation between damage factors and damage and also widely used in engineering and natural hazard studies to calculate the vulnerability. In most cases, damage functions are constructed as fragility or vulnerability curves, and researchers are confused by the similarities between them particularly when they perform interdisciplinary research. Thus, we aim to explain the similarities and differences between fragility and vulnerability curves and their relationship by providing case studies to construct them. In addition, we suggest a simple method to construct the damage functions between damage ratio and volcanic ash thickness using limited damage data. This study comes from the fact that damage functions are generally constructed using damage data. However, there is no available volcanic ash damage data in Korea, and not even enough volcanic disaster data to construct damage functions in the world, compared to other hazards. Using the method suggested in the study and the limited damage data from Japan and New Zealand, we construct Weibull-type functions or linear functions dependent of available data to calculate volcanic ash loss estimation, which we think need to be corrected to make it more suitable for inventory characteristics and environmental conditions in Korea.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.1-13
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• 2012

Seismic fragility functions are derived for probabilistic evaluation of seismic control performance of energy dissipation devices installed in reinforced concrete structures. Displacement-dependent dampers are added to the nonlinear single-degree-of-freedom systems with different natural periods and hysteretic characteristics of which stiffness and strength has uncertainty. Nonlinear time history analysis is conducted for those SDOF systems and the result is processed statistically to obtain seismic fragility functions in the form of log normal distribution. Variation of seismic fragility functions for different parameters of SDOF systems and dampers are investigated and the seismic control performance is assessed probabilistically.