• 대한기계학회논문집A
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• 제33권12호
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• pp.1449-1454
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• 2009

The performance variation of a multibody system is affected by a variation of various design variables of the system. And the effects of design variable variations on the performance variation must be considered in design of a multibody system. Accordingly, a variation analysis of a multibody system needs to be conducted in design of a multibody system. For a variation analysis of a performance, population mean and variance which are called statistical parameters of design variables are needed. However, an evaluation of statistical parameters of design variables is impossible in many practical cases. Therefore, an estimation of statistical parameters of the performance based on sample mean and variance which are called statistic of design variables is needed. In this paper, the variation analysis method for a multibody system based on design variable samples was proposed. And, using the proposed method, a variation analysis of the vehicle ride comfort based on sample statistic of design variables was conducted.

• 산업공학
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• 제16권3호
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• pp.344-351
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• 2003

Critical dimension is one of the most important characteristics of up-to-date integrated circuit devices. Hence, critical dimension control in a semiconductor wafer fabrication process is inevitable in order to achieve optimum device yield as well as electrically specified functions. Currently, in complex semiconductor wafer fabrication processes, statistical methodologies such as Shewhart-type control charts become crucial tools for practitioners. Meanwhile, given a critical dimension sampling plan, the analysis of variance technique can be more effective to investigating critical dimension variation, especially for on-chip and on-wafer variation. In this paper, relating to a typical sampling plan, linear statistical models are presented for the analysis of critical dimension variation. A case study is illustrated regarding a semiconductor wafer fabrication process.

• Communications for Statistical Applications and Methods
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• 제17권5호
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• pp.647-652
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• 2010

By using a Malliavin calculus, we prove the central limit theorem on the power variation of the product of the unordered rectangles associated with a standard Brownian sheet.

• Journal of the Korean Statistical Society
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• 제30권1호
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• pp.99-113
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• 2001

This paper deals with the problem of estimating the means in two inverse Gaussian populations with equal but unknown coefficient of variation. The maximum likelihood estimators are derived by solving a cubic equation and their asymptotic variances are presented for comparative purpose. Monte-Carlo simulation is conducted to investigate the efficiency of the estimators relative to the sample means over a wide range of values for the sample size and the coefficient of variation. The effect on this efficiency under the departure from the assumption of common coefficient of variation is also studied.

• 대한수학교육학회지:수학교육학연구
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• 제16권3호
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• pp.221-249
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• 2006

본 연구의 목적은 초등학교 5학년 학생들이 통계적 변이성 개념과 관련하여 가지고 있는 수학적 지식의 특성과 이것이 수업을 통해 어떻게 변화하는지 알아보는 것이다. 본 연구에서는 초등학교 5학년 학생들이 통계적 변이성 개념과 관련하여 가지고 있는 수학적 지식의 특성을 살펴보기 위하여 사전검사를 실시하였다. 사전검사 결과 드러난 학생들의 수학적 지식의 특성 중 미흡한 측면은 바로 잡고, 잘된 점은 더욱 증가시키기 위해 통계적 변이성 수업을 실시하였다. 통계적 변이성수업 후 학생들은 최적 값의 빈도수나 편중성, 평균, 예측 가능한 안정적인 성향 대신 통계적 변이성 개념을 고려하였다. 그리고 표 그래프 그리기 수업을 통해 이에 대한 이해가 증가하여 표와 그래프가 혼합된 문제를 바르게 해석하였다. 전체적인 분포, 범위가 비슷한 집합을 비교하는 상황에서는 평균을 함께 고려하여 안정적으로 답을 구했다.

• 한국지역사회생활과학회지
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• 제20권4호
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• pp.571-578
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• 2009

This study was to apply the measurement variations of each region of the body to the basic bodice pattern grading and to provide the clothing pattern fit for the human body. Grading variation used in the apparel industry was researched and new grading variation was proposed by analyzing the statistical data of body measurements. The statistical variation in body measurements was applied to set the optimum grading region and variation. Five sizes were used by split grading method and drawn with Bust Circumference and waist length based on the middle size. Differences between the grading pattern and the drawing pattern were analyzed by overlapping them and measuring each region. The measurement variations of drawing patterns between the sizes were very different from those of statistical data. On the other hand, the measurement variations of grading patterns between the sizes and those of statistical data were similar. In summary, the grading pattern by applying the measurement variations to the region of the body was superior to the drawing pattern drawn by the basic measurements for clothing fitness.

• International Journal of Quality Innovation
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• 제1권1호
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• pp.97-105
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• 2000

In this paper, a two-section method for measuring is introduced and the variation sources of measurement process are analysed. Measuring is a special process in general process. Various variation source must be firstly decomposed so that the statistical distribution law of measuring process can be established, and then implement monitoring control of the measuring process. A special method to obtain the measuring variation is discussed, and a monitoring control technique for measuring process is studied based statistical distribution. Towards the end, we briefly introduce software design for the analysis and control of a measurement process.

• Journal of Preventive Medicine and Public Health
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• 제32권1호
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• pp.80-87
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• 1999

Objectives. The Study of Small Area Variation(SAV) is most interesting issue in the health care researches. Most studies of SAV have been concluded the existences of variation on the basis of the magnitude of variation without statistical testing. But it is difficult to explain the existence of variation with this way because variation indicies are easily influenced by several parameters and also their distribution are skewed. So, it needs for the study to investigate the distribution of these indices and develop the statistical testing model. Methods. This study was planned to analyze on the distribution of variation indices such as Extremal Quotient(EQ), Coefficient of Variation(CV), Systematic Component of Variation(SCV) and compare the statistical power among indicies. The simulations was performed on the basis of several assumptions and compared to the empirical data. Results. Main findings can be summarized as follows. 1. If other conditions are constant, the more number of regions, the larger 95 percentile of EQ. But under same situation, 95 percentile of CV and SCV were slightly decreased. 2. If the size of regional population or utilization rate were increased, 95 percentile of all statistics were decreased. Also in the cases of small population size and low utilization rate, 95 percentiles of EQ showed various change contrast to the little change of CV. 3. If the difference at the size of regional population were increased, 95 percentiles of EQ and SCV were increased contrast to the little different of CV. 4. If the utilization rate were increased, 95 percentiles of all indicies were increased. But under the same difference of utilization rate, the power of CV and SCV were increased comparing to no change of the power of EQ. 5. Usually the power of EQ were lower than that of CV or SCV and it is similar between CV and SCV. Conclusions. Therefore, we suggest that in selecting the variation indicies at the SAV, CV or SCV are superior than EQ in terms of significance level and power.

• Journal of the Korean Statistical Society
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• 제13권1호
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• pp.42-47
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• 1984

In this paper, the means of the estimators for the coefficient of variation (CV) in an underlying Pareto distribution are expressed in terms of confluent hypergeometric functions. The numericla values of the biases for the CV estimators in the Pareto distribution are also obtained.

• Communications for Statistical Applications and Methods
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• 제11권1호
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• pp.13-20
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• 2004

A more general version of diffusivity based on total variation of density is defined and an information inequality for median-unbiased estimation is presented. The resulting information inequality can be interpreted as an analogue of the Bhattacharyya system of lower bounds for mean-unbiased estimation. A condition on which the information bound is achieved is also given.