• Journal of the Korean Mathematical Society
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• v.47 no.2
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• pp.385-407
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• 2010

To study the relationship between the levels of chemical pollutants and the number of daily total hospital admissions for respiratory diseases and to find the effect of temperature/relative humidity on the admission number, Wong et al. [17] introduced the varying-coefficient single-index model (VCSIM). As pointed out, it is a popular multivariate nonparametric fitting technique. However, the tests of the model have not been very well developed. In this paper, based on the estimators obtained by the local linear technique, the average method and the one-step back-fitting technique in the VCSIM, the generalized likelihood ratio (GLR) tests for varying-coefficient parts on the VCSIM are established. Under the null hypotheses the new proposed GLR tests follow the $\chi^2$-distribution asymptotically with scale constant and degree of freedom independent of the nuisance parameters, known as Wilks phenomenon. Simulations are conducted to evaluate the test procedure empirically. A real example is used to illustrate the performance of the testing approach.

• Communications for Statistical Applications and Methods
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• v.8 no.3
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• pp.731-737
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• 2001

In this paper, we suggest and implement an internet survey system cooperating the randomized response technique(RRT). We compare it with the direct survey. RRT is an indirect survey method to get true information from the respondent who is conceived to have sensitive character without revealing his/her status. We implement our system(method) based a data-base system, so it common all kind of data obtained through internet surveys. This system also can be used in spot survey independently.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.454-461
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• 2015

This study compares the results of a sled test and FEA(Finite Element Analysis) of a vehicle seatbelt system and aims to propose a method to efficiently reduce the error rate in the results of the FEA. This study evaluates the relative importance of potential causes, applying AHP(Analytic Hierarchy Process) technique in order to improve the reliability of the result of the FEA, and draw a highly reliable result of FEA, conducting a Taguchi Method and optimization for reducing the error rate in the FEA through the design of experiments.

• Journal of the Korean Data and Information Science Society
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• v.16 no.1
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• pp.51-58
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• 2005

The purpose of the Delphi technique is to elicit information and judgments from participants to facilitate problem-solving, planning, and decision-making. It does so without physically assembling the contributors. Instead of it, information is exchanged via mail, FAX, or email. This technique is designed to take advantage of participants' creativity as well as the facilitating effects of group involvement and interaction. It is structured to capitalize on the merits of group problem-solving and minimize the liabilities of group problem-solving. In this paper, we design and implement delphi system using instant messenger.

• Journal of the Korean Institute of Plant Engineering
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• v.23 no.4
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• pp.57-64
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• 2018

User-based collaborative filtering is a method of recommending an item to a user based on the preference of the neighbor users who have similar purchasing history to the target user. User-based collaborative filtering is based on the fact that users are strongly influenced by the opinions of other users with similar interests. Item-based collaborative filtering is a method of recommending an item by comparing the similarity of the user's previously preferred items. In this study, we create a recommendation model using user-based collaborative filtering and item-based collaborative filtering with consumer's consumption data. Collaborative filtering is performed by using RFM (recency, frequency, and monetary) technique with purchasing data to recommend items with high purchase potential. We compared the performance of the recommendation system with the purchase amount and the performance when applying the RFM method. The performance of recommendation system using RFM technique is better.

• The Korean Journal of Applied Statistics
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• v.33 no.2
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• pp.115-122
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• 2020

K-means clustering uses a spherical or elliptical metric to group data points; however, it does not work well for non-convex data such as the concentric circles. Spectral clustering, based on graph theory, is a generalized and robust technique to deal with non-standard type of data such as non-convex data. Results obtained by spectral clustering often outperform traditional clustering such as K-means. In this paper, we review spectral clustering and show important issues in spectral clustering such as determining the number of clusters K, estimation of scale parameter in the adjacency of two points, and the dimension reduction technique in clustering high-dimensional data.

• Communications for Statistical Applications and Methods
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• v.4 no.2
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• pp.445-452
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• 1997

In this paper, twicing technique for the improvement of asymptotic boundary bias in nonparametric regression is considered. Asymptotic mean squared errors of the nonparametric regression estimators are derived at the boundary region by twicing the Nadaraya-Waston and local linear smoothing. Asymptotic biases of the resulting estimators are of order$h^2$and$h^4$ respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.87-94
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• 2015

Recently, management based on statistical data has become a big issue and the importance of the statistics has been emphasized for the management innovation in the defense area. However, the Military Management based on the statistics is hard to expect because of the shortage of the statistics in the military. There are many military information systems having great many data created in real time. Since the infrastructure for gathering data form the many systems and making statistics by using gathered data is not equipped, the usage of the statistics is poor in the military. The Analytical Defense Statistics System is designed to improve effectively the defense management in this study. The new system having the sub-systems of Data Management, Analysis and Service can gather the operational data from interlocked other Defense Operational Systems and produce Defense Statistics by using the gathered data beside providing statistics services. Additionally, the special function for the user oriented statistics production is added to make new statistics by handling many statistics and data. The Data Warehouse is considered to manage the data and Online Analytical Processing tool is used to enhance the efficiency of the data handling. The main functions of the R, which is a well-known analysis program, are considered for the statistical analysis. The Quality Management Technique is applied to find the fault from the data of the regular and irregular type. The new Statistics System will be the essence of the new technology like as Data Warehouse, Business Intelligence, Data Standardization and Statistics Analysis and will be helpful to improve the efficiency of the Military Management.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.1-5
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• 2009

Random beanforming exploits multiuser diversity gain in static channels. Since the gain is restricted by the user population, some extended works have been proposed. Among them, a codebook-based opportunistic beamforming technique forms multiple random beams with small pilots. The technique however has difficulty in designing beams flexibly by the channel statistics. In this paper, we propose a technique forming the multiple random beams by rotating codebooks. The proposed technique enables the flexible design of beams so that multiuser diversity and beam selection diversity are exploited simultaneously with small pilots robust to the channel statistics.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.2
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• pp.71-80
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• 2010

This thesis is purposed on developing security product co-evaluation statistics administrate program which is can administrate or analysis CC accreditation product using by DEVS modeling via portal site of member of CCRA. Via developing security product evaluation statistics administrate program, it can analysis the trend of all countries of the world in many ways, and noticed the ways of evaluation and accreditation of most countries via scheme analysis. Except this, it can analysis the situation of accreditation trend of any countries via data analysis of ICCC 2009. Also, For trend analysis to evaluation technique of CCRA member, it analyzed up to date technology and policy of the evaluation organization and the Certification Authority of most countries. And it peformed analysis the most trend of information security of evaluation authorization in CCRA member countries. In this program, It provide the function of trend statistics analysis which can statically analyzed the evaluation accreditation trends of most countries and automatical statistics by categorization ( by Product, Class and statistics in national) and report creation functions which can easily extraction and use the needed data. It has been updated the related informations until latest accredited product using by CC(Common Criteria) portal home page's data.