• KIPS Transactions on Computer and Communication Systems
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• v.2 no.12
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• pp.541-552
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• 2013

Recently software security of the smart phone is an important issue in the field of information science and technology due to fast propagation of smart technology in our life. The smart phone as the security critical systems which are utilizing in terminal systems of the banking, ubiquitous home management, airline passengers screening, and so on are related to the risk of costs, risk of loss, risk of availability, and risk by usage. For the security issues, software hazard analysis of smart phone is the key approaching method by use of observed failures. In this paper, we propose an efficient integrative framework for software security analysis of the smart phone using Fault Tree Analysis (FTA) and Failure Mode Effect Analysis (FMEA) to gain a convergence security and reliability analysis technique on hand handle devices. And we discuss about that if a failure mode effect analysis performs simpler, not only for improving security but also reducing failure effects on this smart device, the proposed integrative framework is a key solution.

• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.97-105
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• 1984

A method and computer code for the uncertainty analysis in the top event unavailability are developed and tested by combining Monte Carlo Method and Moments method with fault tree reduction technique. Using system fault trees and unavailability data selected in WASH-1400, the efficiency of the proposed method is tested and these results are compared with those obtained by Monte Carlo method. It is shown that the results are sufficiently good in accuracy and computation time is considerably reduced compared with those by Monte Carlo method.

• Journal of the Korean Society of Safety
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• v.1 no.1
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• pp.81-87
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• 1986

System 安全工學 지금까지의 安全을 한마디로 말하면 要素安全 즉 機械, 機具, 設備, 作業力法등 필요한 要素別로 安全對策을 생각해 왔다. 이에 대하여 System安全이라고 하면 機械마다의 工程이 綜合된 전 工程 즉 System全體에 대한 綜合的 安全을 System安全이라고 말할 수 있다. A 工程에서의 缺陷이 事故없이 B 工程으로 흘러가서 事故를 유발할 수도 있고 혹은 C 工程에서 災害를 發生시킬 수도 있으며 그 事故가 當該工程으로 끝나는 것이 아니라 全工程을 마비 시키거나 破괴 시키는 結果를 초래 하게 되므로 從來의 方式에 따른 缺陷工程에 局限된 安全만으로는 設備의 安全性을 確保할 수가 없는 것이다. 여기서 잠시 System安全의 歷史를 살펴보지 않을 수 없다. 元來 System安全은 1950年代 후반 東西간의 軍備경쟁의 와중에서 開發되기 시작한 미사일 開發作業에서 연속 4回의 大事故가 發生하여 수 100萬＄의 損失을 가져 왔다. 이때 그 原內調査 결과 根本的으로 해결하지 않으면 안될 安全性에 관한 몇가지 문제가 지적되기에 이르러 1962年 $\ulcorner$空軍彈道 미사일 開發을 위한 System安全工學$\lrcorner$이라는 最初의 美軍사양서가 公表되고 이후 이 System Safety는 全 美軍에 適用되면서 1977年 6月 MIL-S-882 $A\ulcorner$System安全計劃의 必須條件$\lrcorner$(System Safety Program Reguirment)이 되어 오늘에 이르고 있다. 元來이 規格은 美軍의 裝備에 關한 계약 條件으로 制定되었으나 現在는 一般産業에 있어서의 System 安全에 關한 有力한 지침으로 활용되고 있다. 이와 함께 1974年 美原子力 委員會가 실시한 原子力 플렌트 安全設備에서도 이러한 System技法이 적용되어 System 安全工學의 發展에 크게 기여하게 되었다. 日本國에서는 1976年 勞動者에서 化學플렌트의 安全性設備에서 F.T.A에 의한 再評價를 실시하여 System安全分析 技法이 全國으로 확신 오늘에 이르고 있다. 本章에서는 System安全工學읜 한 解析技法인 F.T.A(Fault Tree Analysis)에 關해서 그 基本的인 事項을 論하고 通用에 關해서는 다음에 論하기로 하겠다.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.117-124
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• 2012

There have been recently introduced new types of urban metro vehicles called LRT (Light Rail Transit) running on elevated guideway such as Uijeongbu VAL(which stands for V$\acute{e}$hicule Automatique L$\acute{e}$ger: Automatic Light Rail Vehicle) system, Yong-In LIM(Linear Induction Motor) system, Incheon international airport MAGLEV(Magnetic Levitated Vehicle) system and Daegu monorail system. Most of accidents by the vehicles are bound to happen on elevated guideway. Therefore, it is of vital importance to analyze hazards related to vehicles running on elevated guideway and study emergency evacuation scenarios applicable in case of accidents on elevated guideway so as to secure the safety of the new types of urban metro vehicles. In this study, FTA(Fault Tree Analysis) model was developed to identify all possible hazards, and all possible evacuation scenarios were studied. It was also confirmed that each hazard can be corresponded to one or more evacuation scenarios. This result shows that passengers can be evacuated according to one of the scenarios identified in this study in case of an accident of "Train Stranded on Elevated Guideway".

• Journal of Power Electronics
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• v.3 no.3
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• pp.145-150
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• 2003

Reliability, availability, and cost have been the major concerns for photovoltaic hybrid systems since their beginning as primary sources for much critical applications like communication units and repeaters. This paper descnbes the performance of two hybrid systems, photovoltaic-battery, wind-turbine coupled with the public-grid (PVBWG) hybrid system and photovoltaic-battery, wind-turbine coupled With the diesel generator (PVBWD) hybrid system The systems are sized to power a typical 300W/48V de telecommunication load continuously throughout the year Such hybrid systems consist of subsystems, which in turn consist of components Failure of anyone of these components may cause failure of the entire system. The reliability and availability basics, and estimation procedure for the two proposals are introduced also in this paper. The PVBWG and PVBWD system configurations are shown with the relevant mean-time-between-faIlure (MTBF) and failure rate (${\lambda}$) of each component. The characteristics equations of the two systems are deduced as a function of operating hours and the percentage of sun and wind availabilities per day. The system probability failure as well as the reliability is estimated based on the fault tree analysis technique. The results show that, by using standard or normal components MTBF, the PVBWG is more reliable and the time of periodic maintenance period is more than one year especially in the rich sites of both sun and wind, but PVBWD competes else Also, in the first five years from the system installation, the system is quit reliable and may not require any maintenance. The results show also, as the sun and wind are available, as the system reliable and available.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.87-95
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• 2011

The urgent VAI(Vital Area Identification) method development is required since 'The Act of Physical Protection and Radiological Emergency' that is established in 2003 requires an evaluation of physical threats in nuclear facilities and an establishment of physical protection in Korea. The KAERI(Korea Atomic Energy Research Institute) has developed the VAI methodology and VAI software called as VIPEX(Vital area Identification Package EXpert) for identifying the vital areas. This study is to demonstrate the applicability of KAERI's VAI methodology to a hypothetical facility, and to identify the importance of information of cable and piping runs when identifying the vital areas. It is necessarily needed to consider cable and piping runs to determine the accurate and realistic TEPS(Top Event Prevention Set). If the information of cable and piping runs of a nuclear power plant is not considered when determining the TEPSs, it is absolutely impossible to acquire the complete TEPSs, and the results could be distorted by missing it. The VIPEX and FTREX(Fault Tree Reliability Evaluation eXpert) properly calculate MCSs and TEPSs using the fault tree model, and provide the most cost-effective method to save the VAI and physical protection costs.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.14-20
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• 2019

This paper presents a safety assessment based approach for the safe operation for PCS(Power Conditioning System) of photovoltaic and energy storage systems, applying FTA. The approach established top events as power outage and a failure likely to cause the largest damage among the potential risks of PCS. Then the Minimal Cut Set (MCS) and the importance of basic events were analyzed for implementing risk assessment. To cope with the objects, the components and their functions of PCS were categorized. To calculate the MCS frequency based on IEEE J Photovolt 2013, IEEE Std. 493-2007 and RAC (EPRD, NPRD), the failure rate and failure mode were produced regarding the basic events. In order to analyze the top event of failure and power outage, it was assumed that failures occurred in DC breaker, AC breaker, SMPS, DC filter, Inverter, CT, PT, DSP board, HMI, AC reactor, MC and EMI filter and Fault Tree was drawn. It is expected that the MCS and the importance of basic event resulting from this study will help find and remove the causes of failure and power outage in PCS for efficient safety management.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.255-261
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• 2013

In this paper, we developed and tested a program for prediction flash fire in a combat system. Purposes of the program are flash fire prediction of combat system for analysis vulnerability and survivability, and visualization for fire-related information. To do this, we defined critical components of the combat system which has probabilities of flash fire occurrence, and proposed Flash Fire Probability Tree which is based on Fault Tree Analysis(FTA). The program visualizes positions of critical components in combat system, positions of penetrated components, selected Flash Fire Probability Tree, temperature profile, and tables for properties of matters.

• Korean Journal of Construction Engineering and Management
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• v.25 no.1
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• pp.42-49
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• 2024

In recent years, the construction industry has diligently focused on improving the quality and safety of buildings through smart technologies. However, there is a growing trend of leakage defects, especially in educational facilities, due to aging. The objective of this study is to analyze the causes of these defects in educational environments using the Fault Tree Analysis (FTA) technique and propose preventive measures based on the findings. The FTA technique is explained through a review of domestic literature, and data from the Educational Support Center from 2019 to 2021 are examined to identify major defects. The construction of the Fault Tree (FT) for leakage defects resulted in the identification of 12 basic events. Subsequently, a comprehensive understanding of the causes of leakage is achieved through FTA analysis, leading to the identification of the primary causes of defects. Leakage defects accounted for 46.8% of all reported issues in educational facilities, with roof (ceiling) leaks being the most common problem. FTA analysis revealed that poor substrate treatment was the main cause of roof (ceiling) leaks, which could be attributed to cracks in the waterproof layer, joint cracks, and microvoids in the waterproof layer. The primary achievement of this research is to provide essential data for preventing leakage defects in educational facilities and developing preventive measures through the FTA technique. These results are expected to significantly enhance the management of educational facilities and the prevention of leakage issues.

• Nuclear Engineering and Technology
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• v.19 no.4
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• pp.279-291
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• 1987

The event tree/fault tree techniques used in the current probabilistic risk assessment (PRA) of nuclear power plants are based on the binary and static description of the components and the system. While these techniques Bay be adequate in most of the safety studies, more advanced techniques, e.g., the Markov reliability analysis, are required to accurately study such problems as the plant availability assessments and technical specifications evaluations that are becoming increasingly important. This paper describes a Markov model for the Reactor Protection System of a pressurized water reactor and presents results of model evaluations for two testing policies in technical specifications.