• Nuclear Engineering and Technology
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• 제44권4호
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• pp.405-414
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• 2012

In this paper, we propose a reliability estimation method for DI&C systems. At the system level, a fault tree model is suggested and Boolean algebra is used to obtain the minimal cut sets. At the component level, an exponential distribution is used to model hardware failures, and Bayesian estimation is suggested to estimate the failure rate. Additionally, a binomial distribution is used to model software failures, and a recently developed software reliability estimation method is suggested to estimate the software failure rate. The overall system reliability is then estimated based on minimal cut sets, hardware failure rates and software failure rates.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2005년도 춘계학술대회
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• pp.279-290
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• 2005

The purpose of this study is to attempt a Analysis of a pointed-end Equipment Arm Safety-Accident for Fault Tree Analysis. Three major techniques were used first problem is Z-Model by which accident Analysis & prevention of a pointed-end Industry can be made, Fault Tree Analysis(FTA) bywhich quantification of a pointed-end Equipment accident Analysis can be made it 5 years in past and the third, manual-written by which minimal cut set to accident can be Identified. A example has been made of issue point a pointed-end Equipment that the Arm in loader happen to Injuries. According to the Analysis lack of safety knowledge, unsafety-behavior seem to be the primal cause of accident. Comparision of the accident cause to actual report demonstratesthat the FTA a efficient tool for Industrial Accident prevention.

• Nuclear Engineering and Technology
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• 제24권1호
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• pp.14-29
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• 1992

원자력 발전소에서 발생하는 공통원인 고장을 분석하기 위한 컴퓨터 코드 COMCAF를 개발하였다. 공통원인 고장을 다룰 때, 먼저 계통의 최소 단절집합들을 공통원인 기본사상들이 고려되지 않은 고장수목으로부터 구한다. 그리고, 공통원인 고장들이 같은 최소 단절집합내의 부품들간에 있는지 또는 서로 다른 최소 단절집합들의 부품들간에 있는지를 고려하여 이들 최소 단절집합들의 발생 확률값을 계산한다. 유사하거나 동일한 부품들간에 공통원인 고장이 있을때는 Basic Para-meter 모델을 사용한다. 그러나, 서로 다른 부품들간에 공통원인 고장이 있을때는 Basic Para-meter모델에 쓰인 Symmetry Assumption을 두개 이상의 부품에 영향을 주는 기본사상들에만 적용한다. Inclusion-Exclusion방법을 사용하여 정점사상확률간을 구한다. 이 경우 같은 최소 단절 집합들에 있는 부품들의 공통원인 고장뿐만아니라 서로 다른 최소 단절집합들에 있는 부품들의 공통원인 고장도 쉽게 고려될 수 있다. 본 연구에서는 이러한 공통원인 고장분석을 가압경수로의 보조 급수계통에 적용하였다. 이들 정점사상의 확률값들을 공통원인 고장이 없는 경우와 비교하였다.

• 한국정밀공학회지
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• 제12권6호
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• pp.105-111
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• 1995

The inverse dynamic equations for 5 link robot including a closed chain have been derived. The closed chain is virtually cut open, and the kinematics and dynamics of the virtual open chain robot are analyzed. The constraints are applied to the virtually cut joints by the Jacobian matrix which represents the configuration of the closed chain. The topology of tree structrued open chain robot is described by a FATHER array. The FATHER array of a link indicates the link tha tis connected in the direction of base link. Based on the inverse dynamic equations, the torque sensitivity models of the 5 link robot have been developed. The sensitivity models characterize the sensitivity of the driving torque with respect to the link parameters. All the procedures are illustrated through the 2 link robot.

• 정보처리학회논문지B
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• 제18B권6호
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• pp.405-414
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• 2011

국내에서 가장 일반적으로 사용되고 있는 규칙 기반 오류 검출 방법은 언어 전문가가 한국어 문서에서 자주 발생하는 오류에 대한 검출 규칙을 경험적으로 구축하고 있다. 그러나 이렇게 경험적으로 규칙을 만들면 새로운 패턴의 문장이 나타날 때마다 규칙이 수정되어야 하므로 일관성 있는 오류 검사 및 교정을 기대할 수 없다. 본 논문에서는 이를 해결하려고 최근 개발되고 있는 어휘의미망 중에서 KorLex와 같은 정규화된 언어 자원을 활용하여 단어들의 범주 정보를 추출하고 이를 이용하여 오류 결정 규칙을 일반화한다. 그러나 현재 구축된 KorLex에는 명사의 계층관계 정보는 구축되어 있지만, 문장 요소와의 관계 정보, 즉, 격틀 정보가 부족하다. 본 논문에서는 용언 의미 오류 결정 규칙으로 사용할 선택제약 명사 클래스를 정보이론에 기초한 MDL과 Tree Cut Model을 활용하여 추출하고 이러한 선택제약 명사 클래스를 사용하여 문법 검사기 규칙을 일반화하는 방안을 제안한다. 실험 결과, 혼동하기 쉬운 네 개의 용언에 대해 목적어로 사용된 명사를 선택제약 명사 클래스로 일반화하여 문법 검사기 오류 결정 규칙 수를 평균 64.8%로 줄였고 기존 명사를 사용한 문법 검사기보다 정확도 측면에서 평균 약 6.2%정도 향상된 결과를 얻을 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1979년도 하계 전자.전기연합학술발표회논문집
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• pp.138-141
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• 1979

The purpose of this paper is to develop an efficient model for the analysis of a John's Chopper Circuit. In the John's Chopper Circuit analysis, the open branches are removed from the associated graph to formulate the modified incidence matrix. An algorithm for the generation of a modified proper tree and fundamental cut set matrix from a network graph is developed, which utilizes much less computer storage space and computation time compared to the classical methods.

• 한국안전학회지
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• 제36권3호
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• pp.66-73
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• 2021

This report documents the results of an at-power internal events Level 1 Probabilistic Safety Assessment (PSA) for a Korea research reactor (KRR). The aim of the study is to determine the accident sequences, construct an internal level 1 PSA model, and estimate the core damage frequency (CDF). The accident quantification is performed using the AIMS-PSA software version 1.2c along with a fault tree reliability evaluation expert (FTREX) quantification engine. The KRR PSA model is quantified using a cut-off value of 1.0E-15/yr to eliminate the non-effective minimal cut sets (MCSs). The final result indicates a point estimate of 4.55E-06/yr for the overall CDF attributable to internal initiating events in the core damage state for the KRR. Loss of Electric Power (LOEP) is the predominant contributor to the total CDF via a single initiating event (3.68E-6/yr), providing 80.9% of the CDF. The second largest contributor is the beam tube loss of coolant accident (LOCA), which accounts for 9.9% (4.49E-07/yr) of the CDF.

• 임산에너지
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• 제21권1호
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• pp.25-31
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• 2002

경상북도 포항 지역에서 생육하는 평균 수령 37년생 상수리나무 천연림 생태계의 지상부 현존생물량 및 연순생산량을 분석하기 위해 2001년 8월에 총 10주의 표본목을 선정 벌목하였다. 수식 Wt=aD/sup b/ 를 사용하여 추정한 지상부 총 현존생물량은 115.47ton/ha으로 나타났다. 부위별 구성비는 수간목부 63.9%, 생지부 19.8%, 수피 14.0%, 그리고 잎 1.2%의 순으로 높았다. 총 연순생산량은 7.89ton/ha이었으며, 부위별 구성비는 현존생물량의 경우와는 다르게 수간목부, 수피, 생지부, 그리고 잎의 순 이었다.

• 한국안전학회지
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• 제26권4호
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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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1975-1988
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• 2019

Short-term traffic flow prediction plays an important role in intelligent transportation systems (ITS) in areas such as transportation management, traffic control and guidance. For short-term traffic flow regression predictions, the main challenge stems from the non-stationary property of traffic flow data. In this paper, we design an ensemble cascading prediction framework based on extremely randomized trees (extra-trees) using a boosting technique called EET to predict the short-term traffic flow under non-stationary environments. Extra-trees is a tree-based ensemble method. It essentially consists of strongly randomizing both the attribute and cut-point choices while splitting a tree node. This mechanism reduces the variance of the model and is, therefore, more suitable for traffic flow regression prediction in non-stationary environments. Moreover, the extra-trees algorithm uses boosting ensemble technique averaging to improve the predictive accuracy and control overfitting. To the best of our knowledge, this is the first time that extra-trees have been used as fundamental building blocks in boosting committee machines. The proposed approach involves predicting 5 min in advance using real-time traffic flow data in the context of inherently considering temporal and spatial correlations. Experiments demonstrate that the proposed method achieves higher accuracy and lower variance and computational complexity when compared to the existing methods.