• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2001년도 정기학술대회
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• pp.311-319
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• 2001

All indices that are now in use assume normally distributed data, and any use of the indices on non-normal data results in inaccurate capability measurements. Therefore, $C_{s}$ is proposed which extends the most useful index to date, the Pearn-Kotz-Johnson $C_{pmk}$, by not only taking into account that the process mean may not lie midway between the specification limits and incorporating a penalty when the mean deviates from its target, but also incorporating a penalty for skewness. Therefore we propose, a new process capability index $C_{psk}$( WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distribution from its mean to create two new distributions which have the same mean but different standard distributions. In this paper we propose an example, a distribution generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods In terms of sensitivity to departure to the process mean/median from the target value for non-normal process.s.s.s.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 봄 학술발표회 논문집
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• pp.161-168
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• 1997

The purpose of this study is to evaluate the possibility of normalization of the distibutions of soil parameters taken from soft ground and the reliability of the safety factors of specific objects on it, including sanitary landfill. Through this study it is found that distributions of soil parameters could be adjusted to appropriate normal distributions as possibility density functions(PDF), and that especially the group of initial cohesions and the coresponding safety factors has a perfect linear correlation. According to those results the PDF to initial cohesion as possibility parameter can not only be tmsformed to the PDF to safety factor but also, conseqently, the reliability of the safety factor(SF) simply based on the mean value of soil parameter(Co) can be calculated or easily picked up from the standrad normal distribution table. It is therefore concluded that even though calculated values of safety factors are over any standard requirements some possibility of risk both to the objects and natural soft ground could be still existing, and also a new standard value for this slope stability control system should be derived just by adjusting old one according to the magnitude of risk possibility.

• 물과 미래
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• 제26권4호
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• pp.73-83
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• 1993

본 연구에서는 우리나라 강우자료에 대한 분리효과를 검토하였다. 2변수 대수정규분포, 3변수 대수정규분포등, TYPE-극치분포, 2변수 Gamma 분포, 3변수 Gamma 분포, Log-Pearson Type-분포, GEV분포 등 7개 분포함수를 선정하고, Monte C미개 실험을 이용하여 과거 강우기록 자료로부터 얻은 왜곡도의 평균과 표준편차와 각 분포형들로부터 모의된 왜곡도의 평균과 표준편차와 차이를 분석하였다. 그 결과 우리나라 강우자료는 3변수 Gamma 분포를 제외한 나머지 6개 분포형에서 분리현상을 보였다.

• 한국컴퓨터정보학회논문지
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• 제21권7호
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• pp.85-92
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• 2016

The law of large numbers, central limit theorem, and connection among binomial distribution, normal distribution, and statistical estimation require dynamics of continuous visualization for students' better understanding of the concepts. During this visualization process, the differences and similarities between statistical probability and mathematical probability that students should observe need to be provided with the intermediate steps in the converging process. We propose a visualization method that can integrate intermediate processes and results through Excel. In this process, students' experiences with dynamic visualization help them to perceive that the results are continuously changed and extracted from multiple situations. Considering modeling as a key process, we developed a classroom exercise using Excel to estimate the population mean and standard deviation by using a sample mean computed from a collection of data out of the population through sampling.

• 한국농공학회논문집
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• 제60권4호
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• pp.83-91
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• 2018

Land reclamation, coastal construction, coastline extension and port construction, all of which involve dredging, are increasingly required to meet the growing economic and societal demands in the coastal zone. During the land reclamation, a portion of landfills are lost from the desired location due to a variety of causes, and therefore prediction of sediment transport is very important for economical and efficient land reclamation management. In this study, laboratory disposal tests were performed using an open channel, and suspended sediment transport was analyzed according to flow velocity and grain size. The relationships between the average and standard deviation of the deposition distance and the flow velocity were almost linear, and the relationships between the average and standard deviation of deposition distance and the grain size were found to have high non-linearity in the form of power law. The deposition distribution of sediments was demonstrated to have log-normal distributions regardless of the flow velocity. Based on the experimental results, modeling of suspended sediment transport was performed using deep neural network, one of deep learning techniques, and the deposition distribution was reproduced through log-normal distribution.

• 산업경영시스템학회지
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• 제16권28호
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• pp.137-143
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• 1993

Generally there are three methods to derive an approximation formula: 1) approching standard normal distribution by appropriate changing variable 2) using standardization variable for expansion 3) deriving approximation formula by direct method. This paper present correction terms having the form of $C_{1/v^{n/2}}/{\;}+{\;}C_2{\;}(n=1,2)$ with respect to $x^2_{\alpha}(v)$ distribution (${\nu}{\;}{\leq}{\;}30$), which minimize the error by EDA method and least square method.

• 보험의학회지
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• 제3권1호
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• pp.103-141
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• 1986

The present study was undertaken to establish the decision standard of builds for the insured by using the ratio of weight-for-height as build index. Materials being examined were the ratio of weight-for-height being calculated from the actually measured heights and weights of a total of 15,838 insured persons who were examined medically at Honam Medical Department of Dong Bang Life Insurance Company, Ltd. from June, 1979 to September, 1985. The ratio of weight-for-height is calculated by the following formula. The ratio of weight-for-height(%)=$\frac{weight(kg){\times}100}{\{height(cm)-100\}{\times}0.9(kg)$ The results were as follows: 1. The distribution of the ratio of weight. for-height of the 15,838 insureds follows Log normal distribution being skewed to the left(the direction of underweight). 2. The ratio of weight-for-height were Log transformed to lead to a sym metrical pattern of distribution in which statistical rules are known to be applied more exactly. Thereafter, the establishment of dicision standard of builds was undertaken by using the log of the ratio of weight-for-height as build index. Through all ages in male, the ratio of weight-for-height indicating the range of standard lives including slight overweighted and underweighted lives besides normal lives is 80-130%, and corresponds to $"M-2{\delta}"-"M+1.5{\delta}"$ and to $M{\pm}20%$ ; in female, 85-135%, and corresponds to $"M-2{\delta}"-"M+1.5{\delta}"$ and to $M{\pm}20%$. Through all ages in male, the ratio of weight-for-height indicating the initial level of super-overweighted and super-underweighted lives is 130-150% and 75-80%,and corresponds to $M+3{\delta}\;and\;M-3{\delta}$ and to M+40% and M-25% respectively;in female, 140-160% and 75-80%, and corresponds to $M+3{\delta}\;and\;M-3{\delta}$ and to M+40%-+50% and M-25% respectively. 3. Author's rating table model for builds(a table of weight per height) is proposed. On the table, the ratings for builds, i. e. standard, super-weighted and super-underweighted lives, are listed.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.479-483
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• 2004

A new calculation method of expected overtopping probability of rubble mound breakwater considering real tide occurrence has been proposed. A calculation method of expected overtopping probability of rubble mound breakwater was proposed by Kweon and Suh (2003). In their calculation, the fluctuation of tidal elevation was expressed by the sinusoidal change that yields the uniform distribution of occurrence frequency. However, the realistic distribution of tidal elevation should influence on the overtopping chance. In this study, the occurrence frequency of tidal elevation obtained from the real sea is included. The tidal elevation used in this study is collected from the east coastal part of Korean peninsular. Analyzing the annual data of the tidal fluctuation measured hourly during 355 days, the distribution of occurrence frequency is formulated utilizing by the normal distribution with one peak. Among the calculation procedures of annual maximum wave height, wave height-period joint distribution, wave run-up height and occurrence frequency of tide, only the annual maximum wave height is again chosen randomly from normal distribution to consider the uncertainty. The others are treated by utilizing the distribution function or relationship itself, It is found that the inclusion of the variability of tidal elevation has great influence on the computation of the expected overtopping probability of rubble mound breakwater. The bigger standard deviation of occurrence frequency is, the lower the overtopping probability of rubble mound breakwater is.

• 동력기계공학회지
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• 제22권6호
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• pp.67-73
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• 2018

Gasoline that meets the quality standards is distributed in Korea. However, consumers who use toluene or solvent mixed with gasoline have appeared due to rising crude oil prices and for the purpose of tax evasion. Gasoline quality standard is enacted by the domestic and international research reference. A wrong fuel can influence automobile performance or environmental issue. Thus, empirical data from this issue is necessary. Therefore, this research observed catalyst influence by gasoline property change and inspect influence of environment. In this study, fuel property evaluation, lean-burn evaluation, and real vehicle exhaust emission test were performed. In the result of fuel property, the fuel "A" was measured to be up to 27% less octane than the normal gasoline and the distillation property was measured 24% higher than normal gasoline. In the test result of single cylinder engine lean-burn test, the fuels "A" and "B" show torque value 20% less than the normal gasoline. As a result of vehicle test using the catalyst, the fuel "A" was increased more than the normal gasoline with 83% THC, 1,806% CO and 128% NOx, and the fuel "B" was increased more than normal gasoline with 1.6% THC, 391% CO and 142% NOx.

• 한국융합학회논문지
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• 제10권11호
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• pp.303-308
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• 2019

본 연구에서는 지진하중에 대한 구조물의 동적해석 과정에서 실제적이고 신뢰성 있는 확률 통계적 지진응답 결과를 얻기 위해 로그정규분포 기반 지진응답 도출 방안을 제안하였다. 이를 위해 미국지질조사국(USGS)에서 제시한 로스앤젤레스 지역 지진재해도에 따라 50년 동안의 발생 초과확률이 2%, 5%, 10%인 30개 지진데이터들을 활용하였다. 해석 대상으로서는 기본적인 동적거동 파악을 위해 단자유도계를 선정, 이의 고유진동주기 별 응답을 나타내는 응답 스팩트럼을 도식하여 응답 추이를 분석하였다. 최종적으로 도출된 로그정규분포 기반 응답의 경우 기존의 정규분포 기반 응답에 비해 모든 고유주기 영역에서 상대적으로 낮은 응답을 보였다. 제안된 로그정규분포 기반의 지진응답 평가는 성능기반내진설계를 위한 경제적 평가 방식으로서의 대안이 될 수 있을 것으로 기대된다.