• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2025-2035
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• 2014

The read range of UHF mobile readers can be extended by a booster for mobile RFID readers (BoMR). But in an environment where multiple BoMRs are installed, the read success rate may be decreased due to signal interference. This paper proposes three arbitration methods based on interference estimation with the purpose of enhancing the read success rate. A central arbitration server manages global information in centralized arbitration method (CAM) without broadcast/multicast communication facility. In fully distributed arbitration method (FDAM), all the arbitration messages are broadcasted from a BoMR to every BoMR, and each BoMR decides with broadcasted global information. Events in FDAM are serialized naturally with broadcasted messages. Cluster Distributed Arbitration Method (CDAM) forms clusters with multicasted BoMRs and a selected BoMR acts as an arbiter in the cluster. Such effects as lengthened read range, improved the read success rates of readers can be obtained by the proposed methods without any hardware modification. In order to evaluate the arbitration methods, the RFID system is modeled by using the DEVS formalism and simulated by using the DEVSim++.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1585-1609
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• 2013

Over recent years, enormous amounts of research in wireless sensor networks (WSNs) have been conducted, due to its multifarious applications such as in environmental monitoring, object tracking, disaster management, manufacturing, monitoring and control. In some of WSN applications dependent the energy-efficient and link reliability are demanded. Hence, this paper presents a routing protocol that considers these two criteria. We propose a new mechanism called Reliable Routing Scheme for Energy-Balanced (RRSEB) to reduce the packets dropped during the data communications. It is based on Swarm Intelligence (SI) using the Ant Colony Optimization (ACO) method. The RRSEB is a self-adaptive method to ensure the high routing reliability in WSNs, if the failures occur due to the movement of the sensor nodes or sensor node's energy depletion. This is done by introducing a new method to create alternative paths together with the data routing obtained during the path discovery stage. The goal of this operation is to update and offer new routing information in order to construct the multiple paths resulting in an increased reliability of the sensor network. From the simulation, we have seen that the proposed method shows better results in terms of packet delivery ratio and energy efficiency.

• Korean Journal of Human Ecology
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• v.22 no.6
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• pp.659-672
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• 2013

Nowadays, sports and outdoor market has been popular and expanding since the implementation of the five-day workweek and change of lifestyle. Outdoor clothing considered exclusive property of the middle-aged individuals in the past. Recently there is a drift towards having outdoor looking at the age of 10-20. The purpose of this study was to analyze the features of purchasing behaviors and demographics by each groups targeting middle school and high school students. The study was conducted with questionnaires towards people who live in the city of Busan and who have experiences of buying outdoor clothing. Data analysis was conducted via SPSS 18.0 with factor analysis, cluster analysis, ANOVA, cross tabulation, frequency analysis and Duncan's multiple range test. The results showed that there were five factors sought for outdoor wear benefits: Individuality/Fashion, Brand, Attractive appearance, Economic value, Comfort/Functional. Cluster analysis showed that there were four groups of outdoor wear benefits sought. Overall, the four groups were different in regard to purchasing behaviors and demographics. Based upon the results mentioned above, this study summarizes the key features of each group and can provide applicable suggestion for conducting strategic marketing activities.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.207-215
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• 1993

In order to statistically predict $O_3$ levels in Seoul, the study used the TMS (telemeted air monitoring system) data from the Department of Environment, which have monitored at 20 sites in 1989 and 1990. Each data in each site was characterized by 6 major criteria pollutants ($SO_2, TSP, CO, NO_2, THC, and O_3$) and 2 meteorological parameters, such as wind speed and wind direction. To select proper variables and to determine each pollutant's behavior, univariate statistical analyses were extensively studied in the beginning, and then various applied statistical techniques like cluster analysis, regression analysis, and expert system have been intensively examined. For the initial study of high level $O_3$ prediction, the raw data set in each site was separated into 2 group based on 60 ppb $O_3$ level. A hierarchical cluster analysis was applied to classify the group based on 60 ppb $O_3$ into small calsses. Each class in each site has its own pattern. Next, multiple regression for each class was repeatedly applied to determine an $O_3$ prediction submodel and to determine outliers in each class based on a certain level of standardized redisual. Thus, a prediction submodel for each homogeneous class could be obtained. The study was extended to model $O_3$ prediction for both on-time basis and 1-hr after basis. Finally, an expect system was used to build a unified classification rule based on examples of the homogenous classes for all of sites. Thus, a concept of high level $O_3$ prediction model was developed for one of $O_3$ alert systems.

• Journal of Korea Multimedia Society
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• v.21 no.8
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• pp.897-908
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• 2018

In this paper, we propose a security framework for a cluster drones network using the MAVLink (Micro Air Vehicle Link) application protocol based on FANET (Flying Ad-hoc Network), which is composed of ad-hoc networks with multiple drones for IoT services such as remote sensing or disaster monitoring. Here, the drones belonging to the cluster construct a FANET network acting as WTRP (Wireless Token Ring Protocol) MAC protocol. Under this network environment, we propose an efficient algorithm applying the Lightweight Encryption Algorithm (LEA) to the CTR (Counter) operation mode of WPA2 (WiFi Protected Access 2) to encrypt the transmitted data through the MAVLink application. And we study how to apply LEA based on CBC (Cipher Block Chaining) operation mode used in WPA2 for message security tag generation. In addition, a modified Diffie-Hellman key exchange method is approached to generate a new key used for encryption and security tag generation. The proposed method and similar methods are compared and analyzed in terms of efficiency.

• Journal of the Korean Home Economics Association
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• v.33 no.4
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• pp.315-327
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• 1995

The objective of this study were to classify the contents of clothing purchase motives and to examine the differences in post-purchase dissatisfaction and satisfaction of clothing according to the clothing purchase motives. Questionnaire was comprised of 36 Likert type items of clothing purchase motive measure, 15 items of post-purchase clothing dissatisfaction measure, and 1 item of satisfaction measures. Samples were 492 women in Incheon, Korean ; 279 were college students and 213 were housewives. The data were analyzed using factor analysis, cluster analysis, one-way ANOVA, Duncan's multiple range test, and χ2-test. The results of the study were the followings : 1. Subjects perceived 'becomingness' to be the most important motive, 'attractiveness of color' the second important, and 'salesperson's recommendation' the least. 2. 6 factors of clothing purchase motives were derived by factor analysis : F.1 'clothing utility and deficiency' ; F.2 'clothing quality' ; F.3 'financial frugality'. 3. Subjects were classified into the three motive groups by cluster analysis of the 6 factors : G.1 'the clothing appearance and others' influence' ; G.2 'the clothing quality and deficiency' ; G.3 'the motiveless'. 4. More college women were distributed in clothing appearance and others' influence group than housewives, while more housewives were distributed in clothing quality and deficiency group. 5. The clothing appearance and others' influence group expressed the highest post-purchase dissatisfaction and the lowest post-purchase satisfaction. The clothing quality and deficiency group expressed the highest post-purchase satisfaction, and the motiveless group expressed the lowest post-purchase dissatisfaction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1363-1376
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• 2020

An improved clustering scheme based on user group is proposed. Every two users are grouped among N-users in the allowed system according to their link gain from large to small. Each user group is numbered sequentially. Two user clusters are obtained according to the principle of maximizing link gain difference for the users in the first and last user groups. The remaining user groups are added to the two existing user clusters according to the parity of the group number. The clustering should be clustered again among the users in either user cluster if the throughput summation of a user cluster in NOMA is less than that of these users in orthogonal multiple access. The simulation results show that the proposed clustering scheme can increase the system throughput by about 8% compared with the hybrid clustering scheme when the number of users requiring service is 12.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.54.2-54.2
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• 2010

The most massive galactic globular cluster, $\omega$ Cen has been observed using recently mounted WFC3/UVIS cameras of Hubble Space Telescope at both near-UV and optical bands. We present the photometry of stars in the central region of $\omega$ Cen in F225W, F275W and F336W bands. The near-UV color-magnitude diagrams and color-color diagrams of stars in $\omega$ Cen show multiple red giant branches and main sequences as already discovered in both ground-based and HST/ACS observations in the optical bands. We modelled the stellar populations of $\omega$ Cen using Yonsei Isochrone, where $\alpha$-particles and helium enhancement processes have been included properly. We compare the best-fit stellar populations obtained from the current near-UV observations to the suggested stellar population models based on optical band data. We also discuss the methodological issues arising when dealing with the near-UV observations; red-leak in near-UV filters and the huge interstellar extinction in near-UV bands compared to the optical bands and its non-linear effect in color-magnitude diagrams.

• The Research Journal of the Costume Culture
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• v.13 no.1
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• pp.161-173
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• 2005

The Main objective of this study was to investigate the relationship between shopping orientations and Knit wear Buying Behavior of female college students in the U.S. age 18 to 33. The questionnaires for this survey were developed to measure knitwear purchasing behavior, including sources of information about knitwear, evaluative criteria of knit wear product, attributes f store preference for knitwear, and shopping orientation. The questionnaire was administered to 119 female college students in the University of California. The data was analyzed by percentage, frequency, mean, factor analysis, Cluster Analysis and ANOVA, Duncan Multiple Range test. The female college students were classified into five subdivisions by cluster analysis; cautious shopping group, recreational shopping group, self-confident shopping group, shopping indifferent group, price conscious shopping group. In the case of fashion information sources of knit wear, significant differences were found according to shopping orientation subdivision in observation of others' and famous people's clothing, fashion shows, fashion articles in magazines, newspapers, and on the Internet, and shop displays. The evaluation criteria of knit wear product were significantly different depending on shopping orientation subdivision in fashionable, brand and store name, appropriate for different occasion, prestige. The store attributes of knitwear were significantly different depending on shopping orientation subdivision in product knowledge of sales personnel, store atmosphere, display of merchandise, layaway payment plan, price level, ease of parking and access, and new fashion.

• The Research Journal of the Costume Culture
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• v.14 no.4
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• pp.542-555
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• 2006

The main objective of this study was to investigate the relationship between benefits segmentation and knitwear purchasing behavior of college female students in the U.S. The questionnaires for this survey were developed to measure knitwear purchasing behavior and benefits segmentation. The questionnaire was administered to 119 female college students in the University of California. The data was analyzed by percentage, frequency, mean, factor analysis, Cluster Analysis and ANOVA, Duncan Multiple Range test. The female college students in the U.S. were classified into fourth subdivisions by the cluster analysis. In the case of fashion information sources of knit wear, significant differences were found according to benefits sought subdivision in observation of famous people's clothing, fashion articles in magazines and newspapers, TV advertisements, Newspaper advertisements, advice of salespeople, and Catalogs. The evaluation criteria of knit wear product of consumers were significantly different depending on benefits sought subdivision in design/style, quality of construction, fashionable, brand and store name, pleasing to others, prestige, and sexy. The store attributes of knitwear product of consumers were significantly different depending on benefits sought subdivision in friendliness of sales personnel, product knowledge of sales personnel, brand names, new fashion, and variety of products. The outlook for the industry of knitwear look to remain bright, there should be a continuous effort to research and invest in consumer satisfaction of knitwear.