• 대한기계학회논문집
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• 제11권3호
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• pp.479-487
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• 1987

본 연구에서는 액적들의 분포상태가 집단연소의 특성에 미치는 영향을 규명하 기 위하여 김의 비정상 집단연소모델에 비균일 액적크기분포와 수밀도분포를 고려한 비균일분포 집단연소모델을 구성하여 이론적으로 해석하였다.

• 천문학회보
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• 제36권2호
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• pp.103.2-103.2
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• 2011

We measure the degree of polarization of the lunar regolith to map the distributions of the age and the particle size. We use a 12cm refracting telescope with a 2k-square pixel color CCD (R band) and a polarization filter. The angular resolution obtained is 3.02 km/pixel. Our goal is to obtain a map of the lunar particle size distribution on the lunar regolith and then that of the age distribution. Polarization of the light scattered by lunar surface contains information on their mean particle size. The mean particle size of the lunar surface has been decreased by continued micro-meteoroid impact over a long period. One can estimate the age of the lunar surface if the mean particle size is known. Particle sizes can be measured through observations of polarization because the mean particle size is related to the maximum polarization and albedo. The age and the particle size of the lunar regolith can give vital information for the future lunar exploration.

• 한국표면공학회지
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• 제28권3호
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• pp.164-173
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• 1995

Based on the potential-theory model for secondary current distribution, we could predict the thickness distributions of electroplating on patterned substrates with the different size of the auxiliary electrode. The substrates contain lithographic patterns at each sample geometry. Each sample geometry had different current distribution at the same condition except the size of the auxiliary electrodes. The size effect of the auxiliary electrode on thickness distribution of electrodeposition on patterned electrode was investigated in a series of experiments. Copper was galvanostatically deposited from an acid-sulfate solution in a reciprocating paddle cell. The thickness distributions of the workpiece scale measured by profilometry across the specimen were in good agreement with the current distribution predicted by boundary element method.

• 산업공학
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• 제17권1호
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• pp.1-12
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• 2004

In a modern semiconductor device manufacturing industry, statistical bin limits on wafer level test bin data are used for minimizing value added to defective product as well as protecting end customers from potential quality and reliability excursion. Most wafer level test bin data show skewed distributions. By Monte Carlo simulation, this paper evaluates methods and sample size effect regarding determination of statistical bin limits. In the simulation, it is assumed that wafer level test bin data follow the Poisson distribution. Hence, typical shapes of the data distribution can be specified in terms of the distribution's parameter. This study examines three different methods; 1) percentile based methodology; 2) data transformation; and 3) Poisson model fitting. The mean square error is adopted as a performance measure for each simulation scenario. Then, a case study is presented. Results show that the percentile and transformation based methods give more stable statistical bin limits associated with the real dataset. However, with highly skewed distributions, the transformation based method should be used with caution in determining statistical bin limits. When the data are well fitted to a certain probability distribution, the model fitting approach can be used in the determination. As for the sample size effect, the mean square error seems to reduce exponentially according to the sample size.

• 한국수자원학회논문집
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• 제46권1호
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• pp.87-97
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• 2013

본 연구에서는 HEC-RAS의 하상변동모형을 이용하여 고농도의 유사가 중소규모의 저수지에 유입하여 삼각주를 형성하는 과정을 유사의 입도분포를 고려하여 해석하였으며, 다음과 같은 결론을 얻을 수 있었다. 먼저, 삼각주의 시공간적인 분포와 년간 저수지에 퇴적되는 입도별 퇴사량을 합리적으로 예측할 수 있었다. 또한 저수지의 특정위치에서 특정시기에 어떤 입도의 유사가 주로 퇴적되는지를 합리적으로 예측할 수 있었다. 이러한 유사의 입도분포를 고려한 모의와 분석은 수자원관련 시설물의 계획 및 유지관리에 필요한 유용한 정보를 제공해 줄 수 있을 것으로 판단된다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권3호
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• pp.213-223
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• 2017

Purpose: The purpose of this study is to arrange the life data analysis literatures based on the Bayesian method quantitatively and provide it as tables. Methods: The Bayesian method produces a more accurate estimates of other traditional methods in a small sample size, and it requires specific algorithm and prior information. Based on these three characteristics of the Bayesian method, the criteria for classifying the literature were taken into account. Results: In many studies, there are comparisons of estimation methods for the Bayesian method and maximum likelihood estimation (MLE), and sample size was greater than 10 and not more than 25. In probability distributions, a variety of distributions were found in addition to the distributions of Weibull commonly used in life data analysis, and MCMC and Lindley's Approximation were used evenly. Finally, Gamma, Uniform, Jeffrey and extension of Jeffrey distributions were evenly used as prior information. Conclusion: To verify the characteristics of the Bayesian method which are more superior to other methods in a smaller sample size, studies in less than 10 samples should be carried out. Also, comparative study is required by various distributions, thereby providing guidelines necessary.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E1호
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• pp.45-48
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• 2006

Mass size distributions of atmospheric particles in Cheonan were determined using a high volume air sampler equipped with a 5-stage cascade impactor. Bimodal distributions that are typical for urban atmospheric particles were obtained. A MMD of the fine particle mode was $0.47{\pm}0.05{\mu}m$ with a GSD of $2.72{\pm}0.21$, and those of the coarse particles were $5.15{\pm}0.18{\mu}m\;and\;2.09{\pm}0.09$, respectively. The annual average concentrations of TSP, PM10, PM2.5, and PM1 were 74.1, 67.5, 54.2, and $42.3{\mu}g/m^3$, respectively. Although the daily PM10 concentrations were under the current National Standard, the daily PM2.5 concentrations frequently exceeded the US Standard even in non asian dust periods. The fractions of PM 10, PM2.5, and PM1 in TSP were $0.905{\pm}0.013,\;0.723{\pm}0.022,\;and\;0.572{\pm}0.029$, respectively, and fine mode particles occupied $57{\sim}72%$ of the total particle mass. The results indicate that fine particles were at the concerning level, and should be the target pollutant for the regional air quality strategy in Cheonan.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.113-113
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• 2006

Polymer separations are used to obtain information on molecular distributions (molecular-weight distribution, chemical-composition distribution, functionality-type distribution, etc.). The existing methods, such as size-exclusion chromatography are reliable, but imperfect. New methods and improvements to existing methods are being studied and some of the results will be discussed. In addition, comprehensive two-dimensional liquid chromatography allows the complete characterization of two mutually dependent distributions. LCxSEC chromatograms provide a very good qualitative impression of the distributions, but calibration is not straightforward. Finally, progress in mass spectrometry allows much better information to be obtained.

• 응용통계연구
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• 제27권1호
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• pp.1-11
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• 2014

세 개 이상의 집단에 대한 생존분포의 비교를 위해 가중 로그순위 검정법(Weighted Logrank test)과 그의 특별한 경우인 로그순위 검정법(Logrank test)이 널리 쓰인다. 그러나 이 방법은 근사적인 분포를 이용한 방법이므로 표본 크기가 작은 경우에는 유효하지 못할 수 있으며, 각 집단의 중도절단 분포가 동일하다는 가정 또한 충족되어야 하기 때문에 이 가정이 충족되지 못할 경우에도 검정법의 유효성을 장담할 수 없다. 표본 크기가 작은 경우에 대한 대안으로, 분포에 대한 가정이 없이 관찰된 자료만으로 검정통계량의 분포를 추정하고 그 분포를 이용해 검정하는 순열 검정법(Permutation test)이 제안되었으나, 순열 검정법 또한 각 집단의 중도절단 분포가 동일하다는 가정이 충족되어야 한다. 따라서 순열 검정법을 향상시킨 순열-대치 검정법(Permutation-Imputation test)이 대안이 될 수 있는데, 이는 대치 단계(Imputation step)에서 귀무가설 하에서의 생존확률이 집단에 의존하지 않도록 자료를 조정한 후 순열 검정 단계(Permutation step)를 통해 검정하는 방법이다. 본 논문에서는 근사적 방법, 순열 검정법, 순열-대치 검정법을 로그순위 검정법과 가중 로그순위 검정법의 한 형태인 Prentice-Wilcoxon 검정법에 적용해 각 검정법의 유효성과 검정력을 비교하였다.