• Journal of Industrial Technology
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• v.25 no.A
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• pp.15-22
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• 2005

In order to evaluate seismic performance of multi-degree-of-freedom bridge structure, moderate lateral load distribution methods using the pushover analysis were developed by many researchers. One of important variables to improve an accuracy of pushover analysis is lateral load distribution. In this study, pushover analyses were performed using the five types of lateral load distribution and seismic performances were evaluated by capacity spectrum method (CSM). To verify an accuracy of suggested lateral load distribution, the maximum displacement estimates by the CSM were compared to those by inelastic time history analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.58-65
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• 1993

The theoretical treatment of statistical properties and distribution relevant to nonlinear random wave field of moderate bandwidth such as peak and trough of wave elevation is an overdue task hampered by the complicated form of nonlinear random waves. In this study, the extreme distribution of nonlinear random waves is derived based on the simplified version of Longuet-Higgins' wave model. It is shown that the band width of wave spectrum has a significant influence on these extreme distribution and the significant wave height is getting larger in an increasing manner as the nonlinearity is getting profound.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1327-1335
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• 2010

In this paper, we want to develop objective priors for the common location parameter in two half-t distributions with unequal scale parameters. The half-t distribution is a non-regular class of distribution. One can not develop the reference prior by using the algorithm of Berger of Bernardo (1989). Specially, we derive the reference priors and prove the propriety of joint posterior distribution under the developed priors. Through the simulation study, we show that the proposed reference prior matches the target coverage probabilities in a frequentist sense.

• Journal of the Korean Data and Information Science Society
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• v.28 no.2
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• pp.443-449
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• 2017

Estimation of population proportion like the distribution rate of LED TV and the prevalence of a disease are often estimated based on survey sample data. Population proportion is generally considered as a special form of population mean. In complex sampling like stratified multistage sampling with unequal probability sampling, the denominator of mean may be random variable and it is estimated like ratio estimator. In this research, we examined the estimation of distribution rate based on stratified multistage sampling, and determined some numerical outcomes using stratified random sample data with about 25% of missing observations. In the data used for this research, the survey weight was determined by deterministic way. So, the weights are not random variable, and the population distribution rate and its variance estimator can be estimated like population mean estimation. When the weights are not random variable, if one estimates the variance of proportion estimator using ratio method, then the variances may be inflated. Therefore, in estimating variance for population proportion, we need to examine the structure of data and survey design before making any decision for estimation methods.

• Journal of the Korean Data and Information Science Society
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• v.28 no.2
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• pp.421-433
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• 2017

The CTE (conditional tail expectation) is a useful risk management measure for a diversified investment portfolio that can be generally estimated by using a transformed univariate distribution. Hong et al. (2016) proposed a multivariate CTE based on multivariate quantile vectors, and explored its characteristics for multivariate normal distributions. Since most real financial data is not distributed symmetrically, it is problematic to apply the CTE to normal distributions. In order to obtain a multivariate CTE for various kinds of joint distributions, distribution fitting methods using copula functions are proposed in this work. Among the many copula functions, the Clayton, Frank, and Gumbel functions are considered, and the multivariate CTEs are obtained by using their generator functions and parameters. These CTEs are compared with CTEs obtained using other distribution functions. The characteristics of the multivariate CTEs are discussed, as are the properties of the distribution functions and their corresponding accuracy. Finally, conclusions are derived and presented with illustrative examples.

• Journal of Technologic Dentistry
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• v.21 no.1
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• pp.115-121
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• 1999

This investing was carried out to evaluate the alteration of stress distribution on teeth and esthetic crowns. Analyzing the stress distribution by the two-dimensional finite element methods, a model of lower 1st molar according to the porcelain fused metal crown an the porcelain fused glass ceramic core crown and the all glass ceramic crown. 1. The pattern of stress distribution showed no apparent differences. 2. The greatest von Mises values were concentrated around the central fossa of all esthetic crowns. The greatest Maximum principle value were concentrated around the interface between the base of esthetic crown and the abutment tooth. It was found that the apatite glass ceramic could be applicable for use in dental crown prosthesis.

• Journal of Ocean Engineering and Technology
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• v.1 no.2
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• pp.83-92
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• 1987

Inorder ot estimate the running life of turbine rotors, fatigue crack propagation low, da/dN = C(${\DELTA}K)^m$, proposed by paris et al. has been widely applied. In this study, fatigue crack propagation rates for 16 samples of 1% Cr-Mo-V rotor steel were measured and statistical characteristics of m and C values in above equation were reviewed. The results are summarized as follows. 1. C and m follow a log-normal distribution and normal distribution, respectively. And the relation of C and shows a strong negative correlation. 2. Fatigue crack propagation equation can be expressed as da/dN=$4.11{\times}10^{-4}({\Delta}K/153.8)^m$, introducing the ralationship C=$C_oK_o^{-m}$. In this case, contribution of $C_o$ distribution to the distribution of log C shows very small compared to degrees of contribution by m.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.73-78
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• 2000

Presented are the estimation of the probability distribution of fatigue crack growth life and reliability assessment of structures by simulating material resistance to fatigue crack growth along a crack path. The material resistance is treated as a Weibull stochastic process. A non-Gaussian stochastic fields simulation method proposed by shimozuka, et al is applied with the statistical data obtained experimentally. Test results are obtained for $\delta K$ constant amplitude load in tension with stress ratio of R=0.2 and three specimen thicknesses of 6,12 and 18mm. This simulation method is useful to estimate the probability distribution of fatigue crack growth life and the smallest life.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.35-40
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• 1986

The production process of a fine size fraction of Korean kaolin by ball milling is studied in this paper by analyzing the size distribution the size distribution of products with the Rosin-rammle formular and the rate process of cumulative size fractions with Alyavdin-Chujyo's formular. The size distribution is found to be divided in three regions a coarser part influenced by feed size an intermediate part where the size distribution shows a clear straight line relationship on Rosin-Rammler chart and the finest part with the ultimate limit of fineness by ball milling. Alyavdin-Chujyo's relationship is found to be valid over a very wide range of milling conditions. For different feed sizes the Alyavdin-Chujyo's relationship gives a group of straight lines with a common intersection point which can be defined as the limiting point of the persistent component region.

• Journal of the Korean Geotechnical Society
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• v.17 no.2
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• pp.21-30
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• 2001

통계적 절리모델링에서 가장 불확실성이 큰 부분이 절리의 길이분포를 추정하는 것이다. 절리선 길이 분포의 추정에서 이제까지는 주로 조사선 조사(scanline survey)를 통한 절리선 반길이 분포를 이용하여 왔다. 이 연구에서는 포이송 디스크 절리모델에 대하여 보다 정밀도가 높은 절리선 길이 분포 추정방법을 찾기 위하여 조사창 조사를 이용하였다. 직사각형 및 원형 조사창에 대하여 양쪽 끝이 조사창 내부에 존재하는 절리선인 양끝내포선의 길이 분포와 한쪽 끝만이 존재하는 한끝내포선의 길이 분포를 이용, 절리선 분포를 추정하는 4개의 관계식을 각각 유도하고 컴퓨터 모의실험을 통하여 유도식의 타당성을 검증한 후 각 유도식을 이용한 절리선 분포의 추정오차를 비교하였다. 또한 절리선 분포로부터 절리직경분포를 계산하는 수치적 해를 유도하고 컴퓨터 모의시험을 통해 수치적 해에 대한 타당성을 검증하였다. 이 연구에서 제시한 조사창 조사를 이용한 절리 길이의 추정방법은 앞으로 절리모델링 분야에서 적용성이 높을 것으로 판단된다.