• Journal of the Korean Society of Safety
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• v.35 no.1
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• pp.107-115
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• 2020

This paper introduces the first vital area identification (VAI) process for the physical protection of nuclear power plants (NPPs) during low power and shutdown (LPSD) operation. This LPSD VAI is based on the 3rd generation VAI method which very efficiently utilizes probabilistic safety assessment (PSA) event trees (ETs). This LPSD VAI process was implemented to the virtual NPP during LPSD operation in this study. Korea Atomic Energy Research Institute (KAERI) had developed the 2nd generation full power VAI method that utilizes whole internal and external (fire and flooding) PSA results of NPPs during full power operation. In order to minimize the huge burden of the 2nd generation full power VAI method, the 3rd generation full power VAI method was developed, which utilizes ETs and minimal PSA fault trees instead of using the whole PSA fault tree. In the 3rd generation full power VAI method, (1) PSA ETs are analyzed, (2) minimal mitigation systems for avoiding core damage are selected from ETs by calculating system-level target sets and prevention sets, (3) relatively small sabotage fault tree that has the systems in the shortest system-level prevention set is composed, (4) room-level target sets and prevention sets are calculated from this small sabotage fault tree, and (5) the rooms in the shortest prevention set are defined as vital areas that should be protected. Currently, the 3rd generation full power VAI method is being employed for the VAI of Korean NPPs. This study is the first development and application of the 3rd generation VAI method to the LPSD VAI of NPP. For the LPSD VAI, (1) many LPSD ETs are classified into a few representative LPSD ETs based on the functional similarity of accident scenarios, (2) a few representative LPSD ETs are simplified with some VAI rules, and then (3) the 3rd generation VAI is performed as mentioned in the previous paragraph. It is well known that the shortest room-level prevention sets that are calculated by the 2nd and 3rd generation VAI methods are identical.

• The Korean Society of Law and Medicine
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• v.8 no.1
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• pp.61-105
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• 2007

The Hospitalized Acquired Infection is defined as the case where the hidden infection or not found at the time of hospitalization occurs during the hospitalized period or, within 30 days to those who performed the surgery operation and then left the hospital. About 2/3 of the Hospitalized Acquired Infection are found as having the internal infection cases that are occurred by the patients' own virus due to the lowered immune system, while about 1/3 are found as having the external infection. The latter 1/3 of the external infection cases can be prevented through the infection management. And in case the new Hospitalized Acquired Infection case occur to the patient who was treated in the hospital, its responsibility issue will matter. As well in the disputes over the Hospitalized Acquired Infection cases, the cause-result relation between the damages and the medical staff's fault and as to whether there is failure of the medical staff or not. personnel should be proved in the medical-malpractice cases. In addition, the difficulties in proving such as expertise, secrecy propensity, discrete propensity and incompleteness will be considered to ease the burden of patient side's proving. Probability theory, Fact based assumption theory, Most adequate plaintiff preassumption or Expressed evidence theories are being discussed as the theories of eased burden of proof. In the result of gathering and reviewing Korea's precedent cases concerning the Hospitalized Acquired Infection, there are only a few accumulated prece dent cases and the attitude of the court also are also not consistent. Therefore, there are the precedents where the cause-result relation and the failure are immediately assumed when (1) timely proximity between the medical behavior and malpractice results, (2) proximity between the medical behavior-applied parts and the malpractice results-found parts, and (3) lack of other causes are separately evidenced; while the are the precedents only when 'the existence of the medical faults based on the common sense' is separately evidenced. It was found that the former and latter cases coexisted. The former is considered as based on the theory that separates the fault and cause-result relation not to consider them together, or regarded as based on the doubts that assumes the medical staff's neglect even though the Hospitalized Acquired Infection might be completely prevented by their efforts. However, the modern medical technology has the limitation as far as the prevention of the Hospitalized Acquired Infection. In conclusion, the assumption of the cause-result relation and that of the fault should be separately reviewed. Therefore, the latter precedents are considered as more reasonable, in the point the faulty behavior may be proved based on the common sense.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.11-22
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• 2019

This study was conducted to identify the causes of the unusually high number of rock slope failures during an expressway construction in Yangsan fault system. The shear strength (cohesion and internal friction angle) of 128 slopes of discontinuities including bedding, joint, and fault planes were re-evaluated through the examination of face mapping and back analysis. The re-evaluated values were analyzed and then compared with the existing data and values used in the design. As a result, the re-evaluated cohesion and friction angles were very low compared to the existing data and the values applied in the design. This incongruity was pointed as the primary reason for the rock slopes failures during the construction. This may be related to the inherent features of clastic sedimentary rocks in the study area, and the discontinuities in the sedimentary rocks in this region played a significant role. Especially, bedding discontinuity showed a big difference compared to the existing data. The shear strength depended on the type of discontinuity in case of clay filled in discontinuity. However, shear strength was independent on the type of discontinuity in case of shattered materials filled in discontinuity.

• Nuclear Engineering and Technology
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• v.43 no.3
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• pp.271-278
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• 2011

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a $2{\times}3$ rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

• Journal of the Korean GEO-environmental Society
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• v.18 no.2
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• pp.21-27
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• 2017

In order to evaluate landslide susceptibility in Yanbian region, this study analyzed 7 factors related to landslide occurrence, such as soil, geology, land use, slope, slope aspect, fault and river by Analytic Hierarchy Process (AHP), and calculated the weights of these 7 hazard-induced factors, determined the internal weights and the relative weights between various factors. According to these weights, combining the Remote Sensing technology (RS) with Geographic Information System technology (GIS), the selected area was evaluated by using GIS raster data analysis function, then landslide susceptibility chart was mapped out. The comprehensive analysis of AHP and GIS showed that there has unstable area with the potential risk of sliding in the research area. The result of landslide susceptibility agrees well with the historical landslides, which proves the accuracy of adopted methods and hazard-induced factors.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1069-1072
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• 1998

Recently the development of design and automation technology and manufacturing method, has reduced the cost of chip, but it becomes more difficult to test IC chip because test technique doesn't keep up with these techniques. In case of IC testing, obtaining test vectors to be able to detect good chip or bad one is very important, but according to increasing complexity, it is very complex and difficult. Another problem is that during testing, there could be capability of physical and electrical damage on chip. Also there is difficulty in synchronization between CUT (circuit under test) and Test equipment〔1〕. Because of these difficulties, built in self test has been proposed. Not only obtaining test vectors but also reducing test time becomes hot issues nowadays. This paper presents a new test BIST(built in self test) method. Proposed BIST implementation reduces test time and obtains high fault coverage. By searching internal nodes in which are inserted test_point_cells〔2〕and allocating TPG(test pattern generation) stages, test length becomes much shorter.

• Journal of the Korean Society of Safety
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• v.7 no.4
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• pp.105-114
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• 1992

This paper presents an study on the knowledge based system for diagnosing the fire causes using the Fuzzy Possibility Measure( FPM ) about the electric-fire ignition. The Ignition values needed for causes diagnosis is computed as FPM for electric-fire ignition based on the internal scale technique that assigns numerically the characteristic difference of facts to the-tin-ear scale. For the convinience of inference, ignition sources are classified into seven types : short, ground fault, leakge of electricity, overcurrent, cord junction overheating, bad Insulation and spark. The system for causes diagnosis of electric-fire is composed of Knowledge Acquisition System, Inference Engine and Man-Machine Interface, The diagnosis system is wrritten in an artificial intelligence langusge “PROLOG” which uses depth-first search and backward chaining schemes in reasoning process.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.369-371
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• 2012

Wireless sensor networks have taken immense interest in healthcare systems in recent years. One example of it is in an in vivo sensor that is deployed in critical and sensitive healthcare applications like artificial retina, cardiac pacemaker, drug delivery, blood pressure, internal heat calculation, glucosemonitoring etc. In vivo sensor nodes exhibit temperature that may be very dangerous for human tissues. However, existing in vivo thermal aware routing approaches suffer from hotspot creation, delay, and computational complexity. These limitations motivate us toward an in vivo virtual backbone, a small subset of nodes, connected to all other nodes and involved in routing of all nodes, -based solution. A virtual backbone is lightweight and its fault-tolerant version allows in vivo sensor nodes to disconnect hotspot paths and to use alternative paths. We have formulated the problem as m-connected k-dominating set problem with minimum temperature cost in in vivo sensor network. This is a combinatorial optimization problem and we have been motivated to use evolutionary approach to solve the problem.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.84-92
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• 2001

In this papers, we proposed the new method in order to diagnosis aging state of transformers. For wavelet transform, Daubechies filter is used, we can obtain wavelet coefficients which is used to extract feature of statistical parameters (maximum value, average value, dispersion skewness, kurtosis) about each acoustic emission signal. Also, these coefficients are used to identify normal and fault signal of internal partial discharge in transformer. As improved method for classification use neural network. Extracted statistical parameters are input into an back-propagation neural network. The number of neurons of hidden layer are obtained through Result of Cross-Validation. The network, after training, can decide whether the test signal is early aging state, alst aging state or normal state. In quantity analysis, capability of proposed method is superior to compared that of classical method.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.444-446
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• 2005

This paper describes a current differential relaying algorithm for power transformers with an advanced compensation algorithm for the secondary current of CTs. The comparative study was conducted with and without the compensating algorithm. The algorithm can reduce the operating time of the relay in the case of an internal fault and improve security for external faults. The performance of the proposed algorithm was investigated when the C100 CT, a quarter of the rated CT(C400), is used.