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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Data and Information Science Society
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Korean Data and Information Science Society
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Volume & Issues
Volume 17, Issue 4 - Nov 2006
Volume 17, Issue 3 - Aug 2006
Volume 17, Issue 2 - May 2006
Volume 17, Issue 1 - Feb 2006
Selecting the target year
Graphical Methods for Evaluating the Degree of the Orthogonal Blocking
Jang, Dae-Heung ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 669~675
When using response surface designs, the experimental trials should be carried out in blocks in case of heterogeneity of conditions. When we use nearly orthogonal blocking, we need evaluate the degree of orthogonal blocking. Graphical methods for evaluating the degree of orthogonal blocking are suggested.
Practical Usage of Positioning Map in University Public Information Strategy
Choi, Kyung-Ho ; Jeon, Ki-Heung ; Hwang, In-Soo ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 677~685
During the previous few years, local universities have experienced a rapid decrease in registration of new student for admission because of the problem of excessive concentration to Seoul metropolitan area and decrease in the number of population under school ages. Even though they are tring to survive from the difficulties by developing new strategies to increase the number of new students, it has no meaning if there is no standpoint of marketing. So, this study suggests that introduction of demander focused marketing concept actively is needed breaking the general and conservative method when the university devise entrance examination strategy. Also, using of positioning map is suggested and the examples are showed as finding differentiation factors with competitive university.
Approximation to GPH Distributions and Its Application
Baek, Jang-Hyun ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 687~705
In this paper we consider GPH distribution that is defined as a distribution for sum of random number of random variables following exponential distribution. We establish approximation process of general distributions to GPH distributions and offer numerical results for various cases to show the accuracy of the approximation. We also propose analysis method of delay distribution of queueing systems using approximation to GPH distributions and offer numerical results for various queueing systems to show applicability of GPH approximation.
Testing the Existence of a Discontinuity Point in the Variance Function
Huh, Jib ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 707~716
When the regression function is discontinuous at a point, the variance function is usually discontinuous at the point. In this case, we had better propose a test for the existence of a discontinuity point with the regression function rather than the variance function. In this paper we consider that the variance function only has a discontinuity point. We propose a nonparametric test for the existence of a discontinuity point with the second moment function since the variance function and the second moment function have the same location and jump size of the discontinuity point. The proposed method is based on the asymptotic distribution of the estimated jump size.
Improved Algorithm for User Based Recommender System
Lee, Hee-Choon ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 717~726
This study is to investigate the MAE of prediction value by collaborative filtering algorithm originated by GroupLens and improved algorithm. To decrease the MAE on the collaborative recommender system on user based, this research proposes the improved algorithm, which reduces the possibility of over estimation of active user's preference mean collaboratively using other user’s preference mean. The result shows the MAE of prediction by improved algorithm is better than original algorithm, so the active user's preference mean used in prediction formula is possibly over estimated.
Reliability Development Programs for Korean Weapon Systems
Hong, Yeon-Woong ; Park, Sung-Ho ; Cho, Kyu-Sang ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 727~742
In general, weapon systems require very high reliability. Recently Korean defense reliability technologies growth rapidly. However, there are some matters of reform in reliability management, reliability assurance, and defense acquisition environment, etc. In this paper, we propose the reliability development plan for Korean defense system as follows; 1) reliability improvement programs for each acquisition stages, 2) reliability improvement methods for logistics support, 3) reliability improvement programs for developers and manufacturers, 4) reform matters for the defense acquisition law, 6) establishment of defense reliability assessment center and defense reliability committee.
A Bayesian Approach to Replacement Policy Based on Cost and Downtime
Jung, Ki-Mun ; Han, Sung-Sil ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 743~752
This paper considers a Bayesian approach to replacement policy model with minimal repair. We use the criterion based on the expected cost and the expected downtime to determine the optimal replacement period. To do so, we obtain the expected cost rate per unit time and the expected downtime per unit time, respectively. When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established to formally express and update the uncertain parameters for determining an optimal maintenance policy. Especially, the overall value function suggested by Jiagn and Ji(2002) is applied to obtain the optimal replacement period. The numerical examples are presented for illustrative purpose.
An Initialization of Active Contour Models(Snakes) using Convex Hull Approximation
Kwak, Young-Tae ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 753~762
The Snakes and GVF used to find object edges dynamically have assigned their initial contour arbitrarily. If the initial contours are located in the neighboring regions of object edges, Snakes and GVF can be close to the true boundary. If not, these will likely to converge to the wrong result. Therefore, this paper proposes a new initialization of Snakes and GVF using convex hull approximation, which initializes the vertex of Snakes and GVF as a convex polygonal contour near object edges. In simulation result, we show that the proposed algorithm has a faster convergence to object edges than the existing methods. Our algorithm also has the advantage of extracting whole edges in real images.
A Study on The Relationship Among Service Quality, Service Value and Customer Satisfaction of Food Service Industries
Lee, Mi-Ock ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 763~774
The purpose of this study is to identify relationship among service quality, service value and customer satisfaction of food service industries. The respondents included 120 customers of K-restaurant in the survey. Data were analyzed by confirmatory factor analysis and cause-effect analysis among the constructs. After research model testing, the following results was obtained : Service Value was influenced directly and positively by the service quality. And customer satisfaction was influenced directly and positively by the service value. But customer satisfaction was not influenced directly and positively by the service quality.
The Effect of Co-rating on the Recommender System of User Base
Lee, Hee-Choon ; Lee, Seok-Jun ; Chung, Young-Jun ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 775~784
This study is to investigate the effect of the number of co-rated users to the MAE. User based collaborative algorithm generally uses similarity weight to compute the relation of active user and other users. The original estimation algorithm of the GroupLens used the Pearson's correlation coefficient, soon after other researchers used various weighting. The Pearson’s correlation coefficient and Vector similarity, which is used in the field of information retrieval, are commonly used to the estimation algorithm. In prediction, we analyze the effect of the number of co-rated users on the user based recommender system.
Estimation in Mixture of Shifted Poisson Distributions with Known Shift Parameters
Lee, Hyun-Jung ; Oh, Chang-Hyuck ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 785~794
Suggested is an EM algorithm for estimation in mixture of shifted Poisson distributions with known shift parameters. For this type of mixture distribution, we have to utilize values of shift parameters to determine whether each of data belongs to some component distribution. We propose a method of estimating values of component information and then follow typical EM methodology. Simulation results show that the algorithm provides reasonable performance for the distribution.
Prediction Models on Internet Auctions
Hong, Chong-Sun ; Song, Ki-Yong ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 795~804
Most internet auction sites open to users the bid history with the ascending order of bid amounts. Whereas eBay.com presents second bid prices, auction.co.kr provides highest bid prices. In this paper, the bidhistory is arranged according to the passage of tim, which can help to understand the situations and trends of bid prices, especially for multiple auctions. This manipulated data can be visualized by using profile plots. The successful bid prices could be estimated based on some prediction models with appropriate prior informations. Both sellers and bidders can be provided useful informations with these statistical analyses, and then fair online auctions in Korea will grow actively and rapidly.
Shrinkage Estimator of Dispersion of an Inverse Gaussian Distribution
Lee, In-Suk ; Park, Young-Soo ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 805~809
In this paper a shrinkage estimator for the measure of dispersion of the inverse Gaussian distribution with known mean is proposed. Also we compare the relative bias and relative efficiency of the proposed estimator with respect to minimum variance unbiased estimator.
The Teaching of Statistics using Excel VBA
Choi, Hyun-Seok ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 811~820
We introduce a program that enhances the interest and understanding of students in Statistics. This program explains various statistical concepts and procedures by showing detailed steps of calculations with graphs and simulations. This program utilizes a readily accessible Excel VBA.
A Study on the Support Vector Machine Based Fuzzy Time Series Model
Seok, Kyung-Ha ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 821~830
This paper develops support vector based fuzzy linear and nonlinear regression models and applies it to forecasting the exchange rate. We use the result of Tanaka(1982, 1987) for crisp input and output. The model makes it possible to forecast the best and worst possible situation based on fewer than 50 observations. We show that the developed model is good through real data.
A Study on Freshmen's Recognition of Their Choice of Colleges
Shin, Jae-Kyoung ; Chang, Duk-Joon ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 831~842
Today rapidly changing internal and external environment of the universities such as the reduction of freshmen quota forces most universities to be facing a dangerous existence. It is an urgent thing for the universities to secure finance and good students. Because it was thought that to know freshmen's recognition of their choice of colleges would serve to establish the screening system of each university, we studied it through the survey of the freshmen in some universities. We randomly chose some national universities, private universities and educational universities to investigate who are responsible for their choice of colleges. It is shown that the influence of their high school teachers upon their students’ choosing universities is no more than 10%. As a result, the establishment of proper policy of admission to each university on its own that makes use of the characteristics of the region and the university will be effective in choosing good students.
Bayesian Multiple Comparison of Bivariate Exponential Populations based on Fractional Bayes Factor
Cho, Jang-Sik ; Cho, Kil-Ho ; Choi, Seung-Bae ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 843~850
In this paper, we consider the Bayesian multiple comparisons problem for K bivariate exponential populations to make inferences on the relationships among the parameters based on observations. And we suggest the Bayesian procedure based on fractional Bayes factor when noninformative priors are applied for the parameters. Also, we give a numerical examples to illustrate our procedure.
A Comparison of NLSY and CPS Data
Jo, Yoon-Ae ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 851~859
The family income distributions of NLSY97 and CPS youth data are compared by using the generalized beta distribution of the second kind. The null hypothesis that the two data sets represent the same underlying population is rejected. The ML estimation suggests that NLSY97 data are oversampled in an income group of $11,308 or less, by about 15.7% compared to CPS data.
Optimal Burn-In Procedures for a System Performing Given Mission
Cha, Ji-Hwan ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 861~869
Burn-in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, the problem of determining optimal burn-in time for a system which performs given mission is considered. It is assumed that the given mission time is not a fixed constant but a random variable which follows an exponential distribution. Assuming that the underlying lifetime distribution of a system has an eventually increasing failure rate function, an upper bound for the optimal burn-in time which maximizes the probability of performing given mission is derived. The obtained result is also applied to an illustrative example.
A Study on Imputation using Adjusted Cohen Method
Chung, Sung-Suk ; Chun, Young-Min ; Lee, Sun-Kyung ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 871~888
Many studies have been done to develop procedures to deal with missing values. Most common method is to reassign the other values to the missing data. The purpose of our study is to suggest adjusted Cohen methods and to compare the efficiency of them with other methods through a simulation study. The adjusted Cohen methods use an auxiliary variable to arrange ranking of the variable with missing values. It leads to a reduced mean square error(MSE) compared with the Cohen method.
Radiosensitivity and the Occurrence of Radiation-related Cataract and Epilation
Tomita, Makoto ; Otake, Masanori ; Moon, Sung-Ho ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 889~904
Our purpose is to ascertain, if possible, whether atomic bomb survivors with cataracts and epilation were more radiosensitive than those survivors with cataracts but without epilation. A major ophthalmologic survey was conducted in Hiroshima and Nagasaki in 1963-64. At that time, 2125 individuals were examined. Among these individuals, estimated eye organ doses, based on the DS86 dosimetry system, and information on the occurrence of epilation within the first 60 days following the bombings are available on 1742. In the analysis of these data we have assumed that each individual represents a sample of one from a binomial distribution, and that the occurrence of cataracts and epilation are independent biological phenomena. We got following results. The threshold for cataract induction and its 95% confidence limits have been estimated from data on the occurrence of cataract and epilation. Among the 1742 study subjects, 40 had both cataracts and severe epilation. The estimated threshold based on these cases is 0.98 sievert(Sv), with 95% lower and upper confidence bounds of 0.72, and 1.32 Sv, respectively, and is highly statistically significant. Among the 27 cases of cataracts where severe epilation was not reported, the estimated threshold is 1.74 Sv with 95% lower and upper confidence bounds of 1.21 Sv, and "not estimable". The difference between these two estimates is not statistically significant although the effect of dose is highly significant in both instances. The potential importance of biases in the DS86 dose estimates is discussed. The difference between the threshold estimated from cataract cases with epilation and that from cases without epilation is not statistically significant at the 5% or 10% level, and thus affords no support for the notion of increased radiosensitivity.
SVC with Modified Hinge Loss Function
Lee, Sang-Bock ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 905~912
Support vector classification(SVC) provides more complete description of the linear and nonlinear relationships between input vectors and classifiers. In this paper we propose to solve the optimization problem of SVC with a modified hinge loss function, which enables to use an iterative reweighted least squares(IRWLS) procedure. We also introduce the approximate cross validation function to select the hyperparameters which affect the performance of SVC. Experimental results are then presented which illustrate the performance of the proposed procedure for classification.
A Note on Interval Approximation of a Fuzzy Number
Hong, Dug-Hun ; Kim, Kyung-Tae ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 913~918
Chanas(2001) introduced the notion of interval approximation of a fuzzy number with the condition that the width of this interval is equal to the width of the expected interval. In this note, this condition is relaxed and the resulting formulae are derived for determining the approximation interval. This interval is compared with the expected interval and approximation interval of a fuzzy number as introduced by Chanas.
MLE for Incomplete Contingency Tables with Lagrangian Multiplier
Kang, Shin-Soo ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 919~925
Maximum likelihood estimate(MLE) is obtained from the partial log-likelihood function for the cell probabilities of two way incomplete contingency tables proposed by Chen and Fienberg(1974). The partial log-likelihood function is modified by adding lagrangian multiplier that constraints can be incorporated with. Variances of MLE estimators of population proportions are derived from the matrix of second derivatives of the loglikelihood with respect to cell probabilities. Simulation results, when data are missing at random, reveal that Complete-case(CC) analysis produces biased estimates of joint probabilities under MAR and less efficient than either MLE or MI. MLE and MI provides consistent results under either the MAR situation. MLE provides more efficient estimates of population proportions than either multiple imputation(MI) based on data augmentation or complete case analysis. The standard errors of MLE from the proposed method using lagrangian multiplier are valid and have less variation than the standard errors from MI and CC.
The Fractional Bayes Factor Approach to the Bayesian Testing of the Weibull Shape Parameter
Cha, Young-Joon ; Cho, Kil-Ho ; Cho, Jang-Sik ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 927~932
The techniques for selecting and evaluating prior distributions are studied over recent years which the primary emphasis is on noninformative priors. But, noninformative priors are typically improper so that such priors are defined only up to arbitrary constants which affect the values of Bayes factors. In this paper, we consider the Bayesian hypotheses testing for the Weibull shape parameter based on fractional Bayes factor which is to remove the arbitrariness of improper priors. Also we present a numerical example to further illustrate our results.
Estimation for the Rayleigh Distribution with Known Parameter under Multiply Type-II Censoring
Han, Jun-Tae ; Kang, Suk-Bok ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 933~943
For multiply Type-II censored samples from two-parameter Rayleigh distribution, we derive some approximate maximum likelihood estimators of parameter in the Rayleigh distribution when the other parameter is known. We also compare the proposed estimators in the sense of the mean squared error for various censored samples.
Compound Linear Test Plan for 3-level Constant Stress Tests
Kim, In-Ho ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 945~952
Several accelerated life test plans use tests at only two levels of stress and thus, have practical limitations. They highly depend upon the assumption of a linear relationship between stress and time-to-failure and use only two extreme stresses that can cause irrelevant failure modes. Thus 3-level stress plans are preferable. When the lifetime distribution of test unit is exponential with mean lifetime
, i=0, 1, 2, 3, we derive the optimum quadratic plan under the assumption that a quadratic relationship exists between stress and log(mean lifetime), and propose the compound linear plans, as an alternative to the optimum quadratic plan. The proposed compound linear plan is better than two other compromise plans for constant stress testing and nearly as good as the optimum quadratic plan, and has the advantage of simplicity.
Multivariate Poisson Distribution Generated via Reduction from Independent Poisson Variates
Kim, Dae-Hak ; Jeong, Heong-Chul ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 953~961
Let's say that we are given a k number of random variables following Poisson distribution that are individually dependent and which forms multivariate Poisson distribution. We particularly dealt with a method of creating random numbers that satisfies the covariance matrix, where the elements of covariance matrix are parameters forming a multivariate Poisson distribution. To create such random numbers, we propose a new algorithm based on the method reducing the number of parameter set and deal with its relationship to the Park et al.(1996) algorithm used in creating multivariate Bernoulli random numbers.
Likelihood Based Confidence Intervals for the Common Scale Parameter in the Inverse Gaussian Distributions
Lee, Woo-Dong ; Cho, Kil-Ho ; Cha, Young-Joon ; Ko, Jung-Hwan ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 963~972
This paper focuses on the likelihood based confidence intervals for two inverse gaussian distributions when the parameter of interest is common scale parameter. Confidence intervals based on signed loglikelihood ratio statistic and modified signed loglikelihood ratio statistics will be compared in small sample through an illustrative simulation study.
Performances of VSI Multivariate Control Charts with Accumulate-Combine Approach
Chang, Duk-Joon ; Heo, Sun-Yeong ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 973~982
Performances of variable sampling interval(VSI) multivariate control charts with accumulate-combine approach for monitoring mean vector of p related quality variables were investigated. Shewhart control chart is also proposed to compare the performances of CUSUM and EWMA charts. Numerical comparisons show that performances of CUSUM and EWMA charts are more efficient than Shewhart chart for small or moderate shifts, and VSI chart is more efficient than fixed sampling interval(FSI) chart. We also found that performances of the CUSUM or EWMA chart with accumulate-combine approach are substantially efficient than those of Shewhart chart.
Long Memory and Covariance Stationarity of Asymmetric Power FIGARCH Model
Lee, O. ; Kim, M.J. ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 983~990
In this paper, we study an asymmetric power fractionally integrated GARCH model and find a region on which the process is stationary ergodic and has long memory property.
A Note on the Minimal Variability Weighting Function Problem
Hong, Dug-Hun ; Kim, Kyung-Tae ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 991~997
Recently, Liu (2005) proposed a special type of weighting function under a given preference index level with the minimal variability similar to the minimal variability OWA operator weights problem proposed by Fuller and Majlender (2003). He solved this problem using a result of classical optimal control theory. In this note, we give a direct elementary proof of this problem without using any known results.
On Profile Likelihood for Gamma Frailty Models
Ha, Il-Do ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 999~1007
The semiparametric gamma frailty models have been often used for multivariate survival analysis because they give an explicit marginal likelihood. The commonly used estimation procedure is the profile likelihood method based on marginal likelihood, which provides the same parameter estimates as the EM algorithm. In this paper we show in finite samples the standard profile-likelihood method can lead to an underestimation of parameters, particularly for the frailty parameter. To overcome this problem, we propose an adjusted profile-likelihood method. For the illustration a numerical example and a small-sample simulation study are presented.
Bayesian Estimation of the Normal Means under Model Perturbation
Kim, Dal-Ho ; Han, Seung-Cheol ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 1009~1019
In this paper, we consider the simultaneous estimation problem for the normal means. We set up the model structure using the several different distributions of the errors for observing their effects of model perturbation for the error terms in obtaining the empirical Bayes and hierarchical Bayes estimators. We compare the performance of those estimators under model perturbation based on a simulation study.
Jackknife Estimation in a Truncated Exponential Distribution with an Uniform Outlier
Lee, Chang-Soo ; Chang, Chu-Seock ; Park, Yang-Woo ;
Journal of the Korean Data and Information Science Society, volume 17, issue 3, 2006, Pages 1021~1028
We shall propose ML, ordinary jackknife and biased reducing estimators of the parameter in the right truncated exponential distribution with an unidentified uniform outlier when the truncated point is unknown and their biases and MSE's are compared numerically each other in the small sample sizes.