• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1146-1156
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• 2021

Single-unit probabilistic safety assessment (SUPSA) has complex Boolean logic equations for accident sequences. Multi-unit probabilistic safety assessment (MUPSA) model is developed by revising and combining SUPSA models in order to reflect plant state combinations (PSCs). These PSCs represent combinations of core damage and non-core damage states of nuclear power plants (NPPs). Since all these Boolean logic equations have complemented gates (not gates), it is not easy to generate exact Boolean solutions. Delete-term approximation method (DTAM) has been widely applied for generating approximate minimal cut sets (MCSs) from the complex Boolean logic equations with complemented gates. By applying DTAM, approximate conditional core damage probability (CCDP) has been calculated in SUPSA and MUPSA. It was found that CCDP calculated by DTAM was overestimated when complemented gates have non-rare events. Especially, the CCDP overestimation drastically increases if seismic SUPSA or MUPSA has complemented gates with many non-rare events. The objective of this study is to suggest a new quantification method named probability subtraction method (PSM) that replaces DTAM. The PSM calculates accurate CCDP even when SUPSA or MUPSA has complemented gates with many non-rare events. In this paper, the PSM is explained, and the accuracy of the PSM is validated by its applications to a few MUPSAs.

• 대한조선학회논문집
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• 제60권1호
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• pp.57-64
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• 2023

Recently, the increased use of anti-ship guided missiles, a weapon system that detects and attacks targets in naval engagement, has come to pose a major threat to the survivability of ships. In order to improve the survivability of ships in response to such anti-ship guided missiles, many studies of means to counteract them have been conducted in militarily advanced countries. The integrated survivability of a ship can be largely divided into susceptibility, vulnerability, and recoverability, and is expressed as the conditional probability, if the ship is hit, of damage and recovery. However, as research on susceptibility is a major military secret of each country, access to it is very limited and there are few publicly available data. Therefore, in this study, a possibility of estimating the susceptibility of ships using an anti-air defense system corresponding to anti-ship guided missiles was reviewed. To this, scenarios during engagement, weapon systems mounted to counter threats, and maximum detection/battle range according to the operational situation of the defense weapon system were defined. In addition, the effectiveness of the anti-air defense system and susceptibility was calculated based on the performance of the weapon system, the crew's ability to operate the weapon system, and the detection probability of the detection/defense system. To evaluate the susceptibility estimation feasibility, the sensitivity of the detailed variables was reviewed, and the usefulness of the established process was confirmed through sensitivity analysis.

• 전기학회논문지
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• 제59권8호
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• pp.1477-1481
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• 2010

In this paper, we propose the classification and tracking method of the hand region using deformable template and condensation. To do this, first, we extract the hand region by using the fuzzy color filter and HCbCr color model. Second, we extract the edge of hand by applying the Canny edge algorithm. Third, we find the first template by calculating the conditional probability between the extracted edge and the model edge. If the accurate template of the first object is decided, the condensation algorithm tries to track it. Finally, we demonstrate the effectiveness and feasibility of the proposed method through some experiments.

• Communications for Statistical Applications and Methods
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• 제2권2호
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• pp.20-32
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• 1995

The concept of positive ageing describes the adverse effects of age on the lifetime of units. Various aspects of this concept are described in terms of conditional probability distribution of residual life times, failure rates, equilibrium distributions, etc. In this paper, we will consider some partial ordering relations of life distributions under residual life functions and equilibrium distributions. Under residual life distributions, we study the relationships of IFR, NBU and NBUFR classes and that of DMRL and NBUE classes, By using WLR ordering comparison between F and its equilibrium $H_F$, we can decide if F belongs to NBUFR class.

• 논리연구
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• 제19권3호
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• pp.369-400
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• 2016

'한 어머니 상금 씨가 낳은 두 아이 가운데 적어도 하나는 딸이다'라는 정보를 입수했을 때 '상금 씨의 두 아이가 모두 딸이다'를 우리는 얼마큼 믿을 수 있는가? 이 확률이 1/3이라는 것은 거의 분명해 보인다. 그런데 상금 씨가 '보미는 내 딸이다'라는 정보를 새로 더 알려줄 경우 많은 학자들은 우리의 확률이 1/3에서 1/2로 바뀌어야 한다고 말한다. 하지만 나는 그 확률이 여전히 1/3에 머물러야 한다고 주장한다. 증거와 가설의 지지 관계나 정보 유입과 확률 변화를 가늠하기 위해 조건화 규칙을 사용할 때 우리가 주의해야 할 점이 있다. 관련 정보 또는 증거가 어떤 절차를 거쳐 우리에게 주어졌는지를 따져보아야 한다. 해당 증거가 마구잡이로 주어졌다고 여길 수 없을 때는 조건화 규칙을 조심해서 사용해야 한다. 다시 말해 특정 관찰, 증언, 증거가 주어지도록 정보를 갖고 있는 누군가가 그 증거를 각별히 선택하지는 않았는지 잘 따져야 한다. 관련 정보 또는 증거가 우연히 주어지지 않고 그 정보를 이미 알고 있는 사람이 그 정보를 각별히 골라 우리에게 제공한 것이라면, 그 정보는 때때로 우리의 믿음직함을 바꿀 만한 정보가 되지 못한다.

• Smart Structures and Systems
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• 제21권5호
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• pp.705-713
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• 2018

High-speed rail (HSR) has been in operation and development in many countries worldwide. The explosive growth of HSR has posed great challenges for operation safety and ride comfort. Among various technological demands on high-speed trains, vibration is an inevitable problem caused by rail/wheel imperfections, vehicle dynamics, and aerodynamic instability. Ride comfort is a key factor in evaluating the operational performance of high-speed trains. In this study, online monitoring data have been acquired from an in-service high-speed train for condition assessment. The measured dynamic response signals at the floor level of a train cabin are processed by the Sperling operator, in which the ride comfort index sequence is used to identify the train's operation condition. In addition, a novel technique that incorporates salient features of Bayesian inference and time series analysis is proposed for outlier detection and change detection. The Bayesian forecasting approach enables the prediction of conditional probabilities. By integrating the Bayesian forecasting approach with time series analysis, one-step forecasting probability density functions (PDFs) can be obtained before proceeding to the next observation. The change detection is conducted by comparing the current model and the alternative model (whose mean value is shifted by a prescribed offset) to determine which one can well fit the actual observation. When the comparison results indicate that the alternative model performs better, then a potential change is detected. If the current observation is a potential outlier or change, Bayes factor and cumulative Bayes factor are derived for further identification. A significant change, if identified, implies that there is a great alteration in the train operation performance due to defects. In this study, two illustrative cases are provided to demonstrate the performance of the proposed method for condition assessment of high-speed trains.

• 산경연구논집
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• 제10권12호
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• pp.35-42
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• 2019

Purpose : This study examines The impact of human resource investment in internal control on stock price crash risk. Effective internal control ensures that information provided is complete and accurate, financial statements are reliable. By overseeing management, internal control systems can reduce agency costs between management and outside parties. In Korea, firms have to disclose information about internal control systems. The working experience of human resources in internal control systems is also provided for interested parties. If a firm hires more experienced internal control personnel, it can better facilitate the disclosure of information. Prior studies reported that information asymmetry between managers and investors increases future stock price crash risk. Therefore, the longer working experience internal control personnel have, the lower probability stock crashes have. Research design, data and methodology : This study analyzed the association between the working experience of internal control personnel and crash risk using regression analysis on KOSPI listed companies for fiscal years 2016 through 2017. The sample consists of 1,034 firm-years of non-financial firms whose fiscal year end on December 31. Career spanning data of internal control personnel was collected from internal control reports. The professionalism(IC_EXP) was measured as the logarithm of the average working experience of internal control personnel in months. Negative conditional skewness(NSKEW) and down-to-up volatility (DUVOL) are used to measure firm-specific crash risk. Both measures are based on firm-specific weekly returns derived from the expanded market model. Results : We find that work experience in internal control environment is negatively related to stock price crashes. Specifically, skewness(NSKEW) and volatility (DUVOL) are reduced when firms have longer tenure of human resources in internal control division. The results imply that firms with experienced internal control personnel are less likely to experience stock price crashes. Conclusions : Stock price crashes occur when investors realize that stock prices have been inflated due to information asymmetry. There is a learning effect when internal control processes are done repetitively. Thus, firms with more experienced internal control personnel could manage their internal control more effectively. The results of this study suggest that firms could decrease information asymmetry by investing in human resources for their internal control system.

• 한국정보과학회논문지:정보통신
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• 제35권2호
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• pp.158-165
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• 2008

이동 애드혹 네트워크 (Mobile Ad-hoc Network, MANET)에서 단말은 제한된 배터리 에너지로 통신하게 된다. 따라서 주어진 배터리를 효율적으로 사용하여 통신하는 방법이 중요하다. 본 논문에서는 기존의 에너지를 고려한 라우팅 방법에 대한 연구를 소개하고 MANET에서 쓰이는 라우팅 프로토콜의 경로 선택 방법을 수정하여 단말의 최대 소모 에너지를 최적화하는 라우팅 방안 (Minimize the Maximum Used Power Routing, MMPR)을 제안한다. 기존의 애드혹 라우팅에서는 단말의 에너지는 고려하지 않고 최소 홉 수를 경로 비용 함수의 메트릭으로 사용하였지만, MMPR은 사용된 에너지를 메트릭으로 사용하여 해당 경로에 대한 비용을 계산한다. MMPR은 경로를 알고자 하는 시작 단말이 자신이 알고 있는 다른 단말의 사용 에너지 메트릭 중 최고 값을 알파로 정하고 경로 비용 계산을 시작한다. 만일 새로운 경로가 현재 알파 값보다 큰 단말을 포함하고 있다면 해당 경로는 경로 선택에서 배제될 가능성이 높아진다. MMPR의 유효성을 시뮬레이션을 통해 검증한 결과, 기존의 대표적인 에너지를 고려한 경로 선택 알고리즘인 CMMBCR과 비교하여 시간 별 최대 사용 에너지 및 시간 별 죽은 단말 개 수에서 개선된 성능을 보여주었다.

• 한국조경학회지
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• 제30권2호
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• pp.39-49
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• 2002

The purpose of this study is to propose an objective and rational methodology for the selection of proposed sites far the National Trust(NT), which is the new alterative proposal far the conservation of natural environments destroyed by injudicious land development and economic growth. That is to enforce many analysis for the effective estimation of rare ecological and landscape resources and to propose a model based on estimation and united indicators. Using the estimative model, we apply it to the selection of the proposed site in micro scale and simultaneously offer the basic methodology of effective and systematic land conservation in macro scale. The results of this study are as follows: 1) The results of analysis for the reliability of estimative items and indicators, presented no problem in that the coefficient of reliability was over 0.7. 2) The correlation measure of the estimative indicator indicated that 'succession'and 'regenerating restorability' were highly correlative in the item of plants. Another three items showed a tendency to be alike. 3) The results of factor analysis on the characteristics of indicators, classified plants into four categories including a stable factor. The item of animals was classified as a stable and rare factor. The item of landscape was classified as a physical and mental factor and the environment as a pollutional and conditional factor. 4) The model of estimation created through factor analysis was valid for the approval of the regression model because significant probability was 0.00. When we consider the NT proposed site as a complex body that is composed of diverse natural and manmade resources, certainly the synthetic methodology of estimation is needed. If these studies are carried out, NT sites will be selected more rationally and effectively than at present. Consequently, they have the potential to play a core role of natural ecosystem conservation in Korea.

• 한국음향학회지
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• 제24권3호
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• pp.150-159
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• 2005

본 논문에서는 임의의 음성을 특정 화자가 발성한 것처럼 들리도록 변환하는 음성 개성 변환 알고리즘에 대해 연구하였다. 제안된 기법은 화자의 음성을 LPC 켑스트럼, 피치, 발성 속도를 사용하여 표현하였으며 각각에 대한 변환 규칙을 생성하여 변환을 수행하였다. LPC 켑스트럼은 혼합 가우시안 모델을 이용한 확률적으로 모델링하고, 두 화자간의 대응관계를 조건 확률로 나타내었다. 확률적인 모델링에 필요한 각종 파라메터들을 얻기 위해 최대 가능도 기법이 사용되었으며, 변환 LPC 켑스트럼은 최소 자승 오차 방법에 근거하여 얻어지도록 하였다. 운율 변환을 위한 변수로 본 논문에서는 피치와 발성 속도를 사용하였으며, 두 음성간의 평균값 비율을 사용하여 운율 변환을 수행하였다. 제안된 기법은 기존 벡터 양자화 기반의 기법과 비교에서, 객관적인 척도로 사용한 평균 켑스트럼 거리 감소율, 가능도 증가율 면에서 우수한 성능을 나타내었다. 주관적인 테스트에서도 기존의 방법과 유사한 인식율을 얻었으며 특히 완만하게 변화하는 스펙트럼 궤적에 따른 고음질이 얻어짐을 확인할 수 있었다.