• ETRI Journal
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• 제14권4호
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• pp.19-27
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• 1992

Since. as is well known, direct computation of the reliability for a large-scaled and complex net work generally requires exponential time, a variety of alternative methods to estimate the network reliability using simulation have been proposed. Monte Carlo sampling is the major approach to estimate the network reliability using simulation. In the paper, a dynamic Monte Carlo sampling method, called conditional minimal cut set (CMCS) algorithm, is suggested. The CMCS algorithm simulates a minimal cut set composed of arcs originated from the (conditional) source node until s-t connectedness is confirmed, then reduces the network on the basis of the states of simulated arcs. We develop the importance sampling estimator and the total hazard estimator and compare the performance of these simulation estimators. It is found that the CMCS algorithm is useful in reducing variance of network reliability estimator.

• 한국전자통신학회논문지
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• 제8권6호
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• pp.899-905
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• 2013

본 논문은 복수카메라 기반 실시간 비행체 검출 및 추적하는 방법에 대해서 설명한다. 정밀하게 가공된 보정체를 필요로 하지 않는 복수카메라 자기보정 기법에 스케일을 추가하여, 간편하게 각 카메라 내부변수와 카메라 사이의 상대위치 관계를 구하는 복수카메라 보정기법을 제시한다. 비행체 검출 및 추적은 파티컬 필터링 기법을 적용하여 수행하는데, 적은수의 샘플로도 비행체 검출을 빠르고 정확하게 할 수 있도록 하는 Ray-based Importance Sampling을 고안했다. 3차원 공간을 일정한 크기의 격자구조로 나누고, 영상 특징점과 사영기하학을 이용하여 이 격자구조 위에 비행체의 이산적인 분포를 구한다. 이 분포에 따라 격자를 샘플링하고, 또 다시, 격자의 중심을 평균으로 하는 가우시안 분포로부터 비행체의 위치를 샘플링 한다. 이 두 단계의 샘플링을 통해 비행체가 있을 가능성이 높은 영역에 샘플을 집중적으로 분포시킬 수가 있다. 그리고, 복수의 카메라 영상으로부터 실시간으로 동기화된 영상 특징점을 검출하기 위하여 GPGPU를 이용한 병렬 영상처리 시스템을 구현하였다. 실험을 통해 제안한 방법의 유효성을 확인할 수 있었다.

• 한국군사과학기술학회지
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• 제15권1호
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• pp.93-100
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• 2012

In this paper, the deterministic optimal design for the tail plane made of composite materials is conducted under the deterministic loading condition and compared with that of the metallic materials. Next, the reliability analysis with five random variables such as loading and material properties of unidirectional prepreg is conducted to examine the probability of failure for the deterministic optimal design results. The MATLAB programing is used for reliability analysis combined with FEA S/W(COMSOL) for structural analysis. The laminated composite is assumed to the equivalent orthotropic material using classical laminated plate theory. The response surface methodology and importance sampling technique are adopted to reduce computational cost with satisfying the accuracy in reliability analysis. As a result, structural weight of composite materials is lighter than that of metals in deterministic optimal design. However, the probability of failure for the deterministic optimal design of the tail plane structures is too high to be neglected. The sensitivity of each variable is also estimated using probabilistic sensitivity analysis to figure out which variables are sensitive to failure. The computational cost is considerably reduced when response surface methodology and importance sampling technique are used. The study of the computationally inexpensive method for reliability-based design optimization will be necessary in further work.

• Journal of the Korean Statistical Society
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• 제31권2호
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• pp.177-198
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• 2002

The estimation of variance components or variance ratios in linear model is an important issue in plant or animal breeding fields, and various estimation methods have been devised to estimate variance components or variance ratios. However, many traits of economic importance in those fields are observed as dichotomous or polychotomous outcomes. The usual estimation methods might not be appropriate for these cases. Recently threshold linear model is considered as an important tool to analyze discrete traits specially in animal breeding field. In this note, we consider a hierarchical Bayesian method for the threshold animal model. Gibbs sampler for making full Bayesian inferences about random effects as well as fixed effects is described to analyze jointly discrete traits and continuous traits. Numerical example of the model with two discrete ordered categorical traits, calving ease of calves from born by heifer and calving ease of calf from born by cow, and one normally distributed trait, birth weight, is provided.

• 대한토목학회논문집
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• 제5권2호
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• pp.67-73
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• 1985

수치지형모형(數値地形模型)(Digital Terrain Model)을 제작(製作)하는데 있어서 보다 더 정확(正確)한 지형정보(地形情報)의 획득방법(獲得方法)이 매우 큰 비중을 차지하고 있다. 본(本) 논문(論文)은 지형정보(地形情報)를 획득(獲得)하는 방법(方法)의 하나인 밀도증가식(密度增加式) 표본추출방법(標本抽出方法)의 정확성(正確性) 분석(分析)에 그 목적(目的)을 두었다. 특히, 정확성(正確性) 분석(分析)에 있어서는 아래와 같은 사항(事項)에 대(對)해 비교분석(比較分析)하였다. - 도화기(圖化機)에 의해 작도된 종래(從來)의 등고선(等高線)(Conventional Contourlines)과 밀도증가식(密度增加式) 표본추출방법(標本抽出方法)을 이용(利用)하여 작도(作圖)한 수치등고선(數値等高線)(Digital Contourlines)과의 위치오차(位置誤差)에 대(對)한 비교분석(比較分析) - 밀도증가식(密度增加式) 표본추출방법(標本抽出方法)의 적용(適用)에 따른 보간점(補間點)에 대(對)한 표고오차(標高誤差)의 분석(分析) 위의 수치시험(數値試驗)을 위하여 등고선(等高線)의 자동작도(自動作圖)에 관한 전산(電算)프로그램을 작성(作成)했다. 시험결과(試驗結果)와 시산치(試算値)와 추출조건(抽出條件)은 정확도(正確度)와 밀접(密接)한 관계를 가지며, 특히 시산치(試算値) 1.0 m이고, 표준형(標準形)인 추출조건(抽出條件)에서는 종래(從來)의 등고선(等高線)과 거의 일치(一致)함을 알 수 있었다.

• 기본간호학회지
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• 제15권1호
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• pp.22-33
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• 2008

Purpose: The purpose of this study was to compare frequency and importance of nursing practice in novice nurses and student nurses. Method: A descriptive design was used with convenience sampling of 292 novice nurses in 2 hospitals with 500 beds and 214 student nurses from 4 universities. Data were collected using a structured questionnaire. Results: 1) The total score for frequency of nursing practice was $2.58{\pm}0.41$ and for the importance of nursing practice was $3.03{\pm}0.36$ in novice nurses and in student nurses the frequency score was $2.66{\pm}0.69$ and the total score for importance was $3.24{\pm}0.35$. 2) The total score for frequency was not different between novice and student nurses, but 9 of the top 10 categories in order of frequency were significantly different. 3) The score for importance between novice nurses and student nurses was significantly different with the student nurses having higher scores than the novice nurses. 4) Frequency scores were not different for students in universities compared to students in community colleges. Conclusion: Novice nurses perform skills associated with medication, but student nurses do not and therefore do not recognize the importance of these skills. Education in nursing needs to identify strategies to strengthen practice in this vulnerable area.

• 여성건강간호학회지
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• 제11권4호
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• pp.324-332
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• 2005

Purpose: The purpose of this research was to identify knowledge of, attitude toward, and the importance of, sexuality in the elderly. Method: By convenience sampling, 152 elderly people aged 60 and over who registered at 3 elderly schools located in W city were selected. Knowledge and attitude toward sexuality were measured with ASKAS. Perceived importance toward sexuality was measured with an instrument developed by the investigator. Data was analyzed by descriptive statistics, t-test, ANOVA, and Pearson's correlation. Results: Elderly males, elderly couples, and elders perceiving themselves as healthy reported higher scores in knowledge on and the importance of sexuality. Elderly males, elders with higher education, and elders perceiving themselves as healthy showed a more acceptable attitude toward sexuality. The higher knowledge of sexuality, the more acceptable the sexuality. The higher knowledge of and more acceptable attitude toward sexuality, the higher significance of sexuality. Conclusions: Sexuality is an important issue in elderly life. To improve knowledge, positive views of sexuality, recognition of its importance, education and consulting programs on sexuality need to be developed, reflecting characteristics of the elderly. These programs should be provided not only to the elderly but also to people caring for the elderly and their families.

• 수산해양교육연구
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• 제27권4호
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• pp.1147-1159
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• 2015

The purpose of this study was to verify the analysis of level of importance and satisfaction in recognitions of elementary school students on useful classes among school sport clubs using Importance-Performance analysis. In order to achieve this objective, samples were taken by using convenience sampling method among non-probability sampling methods, and 384 data were used as the final valid samples for this study except 16 data with missing items or insincere responses. The results of frequency analysis, exploratory factor analysis, independent samples t-test, IPA analysis by using SPSS 20.0 were as follows. First, Iquadrant included education contents of enhance ability to ingenuity, teaching method of provides option, teaching method of encourage participation activity, education contents of the aspect of fun, evaluation of motor function and emotion, education contents of explains key contents easily, and education contents of understanding overall context. II quadrant included education environment of good sport facility, class environment of fair opportunity for activity, class atmosphere of arouses interest, and class atmosphere of autonomous and voluntary. III quadrant included diverse teaching method and instructor's demonstration, class atmosphere of systematic learning, evaluation of fairness, objectivity, and credibility, and an atmosphere that can exercise. IV quadrant included education contents of enable acquisition of knowledge and degree of improvement into consideration, and class atmosphere of trust and respect between instructor and student.

• 대한전자공학회논문지SP
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• 제48권5호
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• pp.16-22
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• 2011

본 논문에서는 배경 차분에 의해 객체를 검출하고 확률적으로 표본화된 입자 필터링(particle filtering)기법을 사용한 다중객체 추적 기법을 제안한다. 확률적으로 표본화된 입자들을 사용하여 다중 객체에 독립적으로 적용할 때 발생하는 계산 복잡도(computational complexity)를 감소시키는 동시에 안정적인 추적을 가능하게 하였다. 객체의 색상정보를 사용한 히스토그램 분포에 의한 관측 모델(observation model)을 구성하고 객체의 움직임 정보를 위해 동적 모델을 공식화하여 영상을 해석하였다. 전체적인 추적 시스템은 베이시언 최대 우도 기법(Bayesian maximum likelihood method)을 근간으로 하되, 입자 필터링을 객체 추적에 적용하여 실용적인 현실 객체 추적 상황에도 강건하게 대처할 수 있음을 실험을 통해서 증명하였다.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.690-703
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• 2010

Sampling based uncertainty analysis was carried out to quantify uncertainty in predictions of best estimate code RELAP5/MOD3.2 for a thermal hydraulic test (10% hot leg break LOCA) performed in the Large Scale Test Facility (LSTF) as a part of an IAEA coordinated research project. The nodalisation of the test facility was qualified for both steady state and transient level by systematically applying the procedures led by uncertainty methodology based on accuracy extrapolation (UMAE); uncertainty analysis was carried out using the Latin hypercube sampling (LHS) method to evaluate uncertainty for ten input parameters. Sixteen output parameters were selected for uncertainty evaluation and uncertainty band between $5^{th}$ and $95^{th}$ percentile of the output parameters were evaluated. It was observed that the uncertainty band for the primary pressure during two phase blowdown is larger than that of the remaining period. Similarly, a larger uncertainty band is observed relating to accumulator injection flow during reflood phase. Importance analysis was also carried out and standard rank regression coefficients were computed to quantify the effect of each individual input parameter on output parameters. It was observed that the break discharge coefficient is the most important uncertain parameter relating to the prediction of all the primary side parameters and that the steam generator (SG) relief pressure setting is the most important parameter in predicting the SG secondary pressure.