• 환경영향평가
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• 제6권1호
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• pp.111-119
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• 1997

This study was carried out to suggest the best statistical test which may be used to quantify the change of water quality between two groups. Traditional t-test may not be used in cases where the normality of underlying population distribution is not assured. Three non-parametric tests which are based on the relative order of the measurements, were studied to find out the applicability in water quality data analysis. The sign test is based on the sign of the deviation of the measurement from the median value, and the binomial distribution table is used. The signed rank test utilizes not only the sign but also the magnitude of the deviation. The Wilcoxon rank-sum test which is basically same as Mann-Whitney test, tests the mean difference between two independent samples which may have missing data. Among the three non-parametric tests studied, the singed rank test was found out to be applicable in the quantification of the change of water quality between two samples.

• 대한한의학회지
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• 제25권3호
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• pp.99-104
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• 2004

Objectives : To study the Live Blood Condition of chronic shoulder measurement. Methods : Twenty-one patients were studied. The observation items of the Live Blood Condition are the form's abnormality and cohesion of red blood cells, the abnormality of hemoglobin and the toxicity in plasma. Results : 1. The form's abnormality and cohesion of red blood cells observed were erythrocyte aggregation (8 persons), Rouleau (3 persons), target cells (7 persons), ovalocytes (3 persons), poikilocytes (2 persons). Double conditions observed were erythrocyte aggregation & target cells (3 persons), erythrocyte aggregation & poikilocytes (1 person), target cells & ovalocytes (l person). 2. The abnormality of hemoglobin and the toxicity in plasma observed were cholesterol crystals (5 persons), atherosclerotic plaque (3 persons), chylous (6 persons). 3. The form normality of red blood was generally observed in one woman. The normality of hemoglobin and the non-toxicity in plasma were generally observed in seven women. Conclusions : According to this study of the Live Blood Condition of women's shoulder measurement, these results suggest that the twenty-one patients evidence the conditions of extravasated blood and phlegm.

• Communications for Statistical Applications and Methods
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• 제23권6호
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• pp.497-515
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• 2016

Modern processes often monitor more than one quality characteristic that are referred to as multivariate statistical process control (MSPC) procedures. The MSPC is the most rapidly developing sector of statistical process control and increases interest in the simultaneous inspection of several related quality characteristics. Most multivariate detection procedures based on a multi-normality assumptions are independent, but there are many processes that assume non-normality and correlation. Many multivariate control charts have a lack of related joint distribution. Copulas are tool to construct multivariate modelling and formalizing the dependence structure between random variables and applied in several fields. From copula literature review, there are a few copula to apply in MSPC that have multivariate control charts, and represent a successful tool to identify an out-of-control process. This paper presents various types of copulas modelling for the multivariate control chart. The performance measures of the control chart are the average run length (ARL) and the average number of observations to signal (ANOS). Furthermore, a Monte Carlo simulation is shown when the observations were from an exponential distribution.

• 산업공학
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• 제24권4호
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• pp.314-322
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• 2011

This study analyzes a relationship between Data Envelopment Analysis(DEA) efficiency scores and a normalization index in order to examine the validity of DEA models. A normalization index concerned in this study is 'sales per R&D project fund' which is regarded as a crucial R&D project performance evaluation index in practice. For this correlation analysis, three distinct DEA models are selected such as DEA basic model, DEA/AR-I revised model(i.e. DEA basic model with Acceptance Region Type I constraints) and Super-Efficiency(SE) model. Especially, SE model is adopted where efficient R&D projects(i.e. Decision Making Units, DMU's) with DEA efficiency score of unity from DEA basic model can be further differentiated in ranks. Considering the non-normality and outliers, two rank correlation coefficients such as Spearman's ${\rho}_s$ and Kendall's ${\tau}_B$ are investigated in addition to Pearson's ${\gamma}$. With an up-to-date empirical massive dataset of n = 482 R&D projects associated with R&D Loan Program of Korea Information Communication Promotion Fund in the year of 2011, statistically significant (+) correlations are verified between the normalization index and every model's DEA efficiency scores with all three correlation coefficients. Especially, the congruence verified in this empirical analysis can be a useful reference for enhancing the practitioner's acceptability onto DEA efficiency scores as a real-world R&D project performance evaluation index.

• 감성과학
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• 제12권1호
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• pp.55-64
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• 2009

기존의 전문성 연구들은 참가자들에게 일상적인 과제를 수행하게 함으로써 전문가와 초보자들의 차이를 알아보고자 하였다. 하지만, 본 연구는 일상적 비행 상황에 익숙해진 조종사들이 이전에 경험해보지 못한 새로운 비행 상황에서도 유연하게 대처할 수 있는지 알아보고자 하였다. 즉, 조종사의 숙련정도에 따라 정상적 및 비정상적 상황에서의 상황인식 능력이 차이가 나는지 관찰하였고 추가적으로, 전문성이 자극 제시 시간에 따른 수행변화에 영향을 주는지 알아보았다. 이를 위해 42명의 조종사들을 전문성의 정도에 따라 초보자와 전문가 집단으로 나누고 이들의 수행이 상황의 특수성 및 자극 제시 시간에 따라 어떻게 달라지는지 알아보았다. 연구를 위하여 조종실 계기판을 모방한 동영상이 제작되었는데, 동영상에 보여지는 계기판들이 모두 정상으로 움직이는 정상적 상황과 이들 중 하나의 계기가 오작동을 일으키는 비정상 상황이 연출되었다. 또한 상황을 지각하기 위한 시간의 차이가 전문성에 따라 다른 효과를 가져오는지 살펴보기 위해서 계기판 상황이 오랫동안 제시되는 긴 제시 조건과 상대적으로 짧게 제시되는 조건으로 조작되었다. 실험 결과, 정상적인 상황에서는 초보자와 전문가 집단 사이의 상황 인식이 유의한 차이가 없었으나, 비정상적인 상황에서는 전문가 집단의 상황인식이 초보자 집단보다 유의하게 높은 것으로 나타났다. 또한, 비행 상황의 제시 시간이 짧아졌을 때 조종사들의 전반적인 상황인식 정확도가 떨어졌지만, 전문가와 초보자의 수행차이는 변함없이 초보자 집단에 비해 전문가 집단의 높은 수행이 유지되었다. 비행 상황의 특수성과 제시 시간의 상호작용에 따라 초보자와 전문가의 상황인식은 어떻게 달라지는지 보았을 때, 비행 상황의 제시 시간이 길고 짧음에 관계없이 정상적 상황에서는 초보자와 전문가 집단의 상황인식 차이가 나타나지 않았으나, 비정상적 상황에서는 전문가 집단의 상황인식 정확도가 초보자 집단 보다 유의하게 높은 것으로 나타났다. 전반적으로 볼 때, 비정상적 상황은 전문가 집단의 수행에 미치는 영향에는 큰 영향을 미치니 못하나 초보자 집단의 수행에는 현저한 영향을 미치는 것으로 나타났다.

• Communications for Statistical Applications and Methods
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• 제20권2호
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• pp.147-155
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• 2013

To determine whether each coefficient is equal to zero or not, usual $t$-tests are a popular choice (among others) in linear regression to practitioners because all statistical packages provide the statistics and their corresponding $p$-values. Under smaller samples (especially with non-normal errors) the tests often fail to correctly detect statistical significance. We propose a permutation approach by adopting a sufficient dimension reduction methodology to overcome this deficit. Numerical studies confirm that the proposed method has potential advantages over the t-tests. In addition, data analysis is also presented.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 춘계학술대회
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• pp.393-400
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• 2009

품질향상을 위한 효과적인 공정관리체계는 기업의 생존에 있어서 매우 중요하다. 최근에는 제품의 수명과 관련된 신뢰성이 강조되면서, 신뢰성분포로 불리는 비정규분포하에서의 공정관리가 핵심과제로 여겨지고 있다. 특히 품질특성치가 비정규분포를 따를때, 정규가설에 기초한 공정관리기술을 사용한다면 심각한 오류가 초래될 수 있기 때문에, 비정규분포에서의 관리도와 신뢰성샘플링계획에 대한 중요성이 강조되고 있다. 본 연구의 목적은 비정규분포에서의 관리도와 신뢰성샘플링계획에 대한 최근연구를 조사하고, 보다 합리적이고 신뢰도 높은 공정분석에 대한 연구동향을 소개함으로써, 비정규분포하에서의 공정관리에 대한 발전적인 연구방향을 제시하는 것이다.

• 감성과학
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• 제19권2호
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• pp.89-100
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• 2016

Inclusive design is increasingly gaining attention, as some people find using products difficult after becoming physically impaired, despite daily use. However, making inclusive products is a challenge for designers or companies, as a lack of knowledge and tools stems their low involvement in it. Developing inclusive design tools is thus needed. This study developed criteria to assess upper extremity capabilities corresponding to specific daily activities. A questionnaire survey was conducted among 58 physiatrists and orthopedists. Non-parametric statistics were employed and medians were adopted as representative scores in the assessment criteria based on normality and reliability test results, non-normal data, and strong reliability of respondents in ranking. Consequently, an assessment tool was developed with 14 criteria (divided into range of motion and strength) and capability scores between 0 and 100, which discerned the moderately impaired from the severely disabled and fully capable. Since the doctors agreed to adopt the criteria but assign numeric values, especially for mild impairments, their capability assessment perception was likely influenced by dichotomy. To compensate for these deficits, qualitative or ergonomic approaches are considered simultaneously.

• 교육시설 논문지
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• 제24권6호
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• pp.3-10
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• 2017

The efforts for sustainable development in building construction is widely applied by global organizations, governments, etc. However, according to the researchers, if the green rating systems on the building, it is reported that construction costs and durations are increased compared to conventional buildings. In this respect, the objective of this study is to identify the construction costs between LEED and non-LEED buildings. The scope of this study is limited in 21 university buildings of Canada. The methodology is as follows: First, the data of LEED and non-LEED buildings are collected in every university building. Second, the average construction costs per square meter is collected and normality check is conducted. Third, to identify statistical significance, the difference of average construction costs is analyzed by using T-test. As a result, it is concluded that the construction costs of LEED buildings are increased by approximately 3.8% more than non-LEED buildings. In the future, the results of this study can be applied to analyzing the additional costs according to the LEED grade in educational buildings.

• 대한기계학회논문집A
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• 제24권2호
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• pp.472-480
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• 2000

A macroscopic yield criterion for porous solids with pressure-sensitive matrices modeled by Coulomb's yield criterion was obtained by generalizing Gurson's yield criterion with consideration of the hydrostatic yield stresses for a spherical thick-walled shell and by fitting the finite element results of a voided cube. The macroscopic yield criterion is valid for negative mean normal stresses as well as for positive mean normal stresses. From the yield criterion, a plastic potential function for the porous solids was derived either for plastic normality flow or for plastic non-normality flow of pressure- sensitive matrices. In addition, the elastic relation, an evolution equation of the plastic flow stress of the matrices and an evolution equation of the void volume fraction were presented to complete a set of constitutive relations. The set of constitutive relations was implemented into a finite element code ABAQUS to analyze the material behavior of rubber-toughened epoxies. The cavitation and the deformation behavior were analyzed around a crack tip under three-point bending and around notch tips under four-point bending. In the numerical analyses, the cavitation of rubber particles was considered via a stress-controlled nucleation model. The numerical results indicate that a reasonable cavitation zone can be obtained with void nucleation controlled by the macroscopic mean normal stress, and a plastic zone is smaller around a notch tip under compression than under tension. These numerical results agree well with corresponding experimental results on the cavitation and plastic zones.