• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.576-579
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• 2009

The amount of incoming e-mails is increasing rapidly due to the wide usage of Internet. Therefore, it is more required to classify incoming e-mails efficiently and accurately. Currently, the e-mail classification techniques are focused on two way classification to filter spam mails from normal ones based mainly on Bayesian and Rule. The clustering method has been used for the multi-way classification of e-mails. But it has a disadvantage of low accuracy of classification. In this paper, we propose a novel multi-way e-mail classification method that uses PCA for automatic category generation and dynamic category hierarchy for high accuracy of classification. It classifies a huge amount of incoming e-mails automatically, efficiently, and accurately.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.6
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• pp.2094-2114
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• 2022

Due to the wide application of fifth generation communication, wireless sensor networks have become an indispensable part in our daily life. In this paper, we analyze physical layer security for two-way relay with energy harvesting (EH), where power splitter is considered at relay. And two kinds of combined methods, i.e., selection combining (SC) and maximum ratio combining (MRC) schemes, are employed at eavesdropper. What's more, the closed-form expressions for security performance are derived. For comparison purposes, this security behaviors for orthogonal multiple access (OMA) networks are also investigated. To gain deeper insights, the end-to-end throughput and approximate derivations of secrecy outage probability (SOP) under the high signal-to-noise ratio (SNR) regime are studied. Practical Monte-Carlo simulative results verify the numerical analysis and indicate that: i) The secure performance of SC scheme is superior to MRC scheme because of being applied on eavesdropper; ii) The secure behaviors can be affected by various parameters like power allocation coefficients, transmission rate, etc; iii) In the low and medium SNR region, the security and channel capacity are higher for cooperative non-orthogonal multiple access (NOMA) systems in contrast with OMA systems; iv) The systematic throughput can be improved by changing the energy conversion efficiency and power splitting factor. The purpose of this study is to provide theoretical direction and design of secure communication.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.160-166
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• 2006

Optical Fiber Bragg Grating sensor has a good performance to measure microscopic displacement which can measure strain of lining concrete and cylindrical structure like high intensity containment building and it can present many advantages like a corrosion resistance from the durability point of view. Then it can measure plane geometrical displacement of cylindrical structures with two-way displacement FBG sensor module. According to the test result, measurement of FBG sensor is better performance than other electric sensor system and 2D-level measurement. As a test result, Resolution of the two-way displacement sensor module with FBG sensors are more 10 times than other LVDT or 2D surveying.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.1037-1047
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• 2005

The purpose of this study was to find out consumer's store patronage mix behavior among different types of apparel stores according to interaction between clothing items and situations. The subjects of this study were female adults who lived in Seoul. The sampling method was quota sampling. The data was obtained from 391 questionnaires. The data were analyzed using frequency, one-way ANOVA, Duncan test, and two-way ANOVA by means of SPSS. The results were as follows; 1. According to, clothing items, store patronage mix of consumer was found to be significantly different in cases of department stores and high-fashion boutiques, brand stores, discount stores of famous brands, mass-wholesale stores and mass-agent stores. 2. According to the situations, patronized store types were found to be significantly different among department store and high-fashion boutiques, brand stores, discount stores of famous brands, mass-wholesale stores and mass-agent stores. In a gift-purchasing situation, department stores and high-fashion boutiques got the highest score, in a self-usage situation, mass-wholesale stores, discount stores of famous brands and brand stores got the highest score. 3. Store patronage mix of consumer was found to be significantly related to the interaction between clothing items and situations. Department stores and high-fashion boutiques have the highest score far a consumer to purchase a suit for a gift, meanwhile brand stores have the highest score for self·usage.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.82-88
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• 2012

The usage of recycling agent is the most effective way of enhancing the performance of recycled asphalt pavement. Generally, many countries accepted these recycling agents retarding the various types of cracks resulted in binder aging. Contrary to such general tendency, recycling agents are used as very small amount in domestic recycling plant. The main reason of this is relatively high price of recycling agent. Even though agent price is high, agent can be a effective and economical way of alternative in asphalt recycling. In this study, penetration and softning point test performed by using RTFO(Rolling Thin Film Oven) aged binder. And, PG(Performance Grade) at high temperature, fatigue and MSCR(Multi Stress Creep and Recovery) tests exercised. The oil type agent is worked well to retrieving target penetration number. In PG test, $G^*/sin{\delta}$ of agents identically showed high value and polymer type agent is good at recovery value.

• Journal of The Korean Association For Science Education
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• v.25 no.5
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• pp.563-570
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• 2005

This study investigated the relationships among middle school students' understanding about the nature of scientific knowledge, conceptual understanding, and learning strategies. Grade 7 students (N=162) in Incheon completed the nature of scientific knowledge scales (NSKS) and a learning strategy questionnaire. After learning density by way of a CAl program, a conception test was administered. Results indicated that students' conceptual understanding and both deep and surface learning strategies were significantly correlated to their understanding about the nature of scientific knowledge. A cluster analysis was used to classify students on the basis of their deep and surface learning strategies. Three clusters of students with distinctive learning strategy patterns were found; high deep-low surface strategy (cluster 1), low deep-high surface strategy (cluster 2), and high deep-high surface strategy (cluster 3). One-way ANOVA results revealed that the scores of cluster 3 were significantly higher than those of the others in the NSKS and the conception test. Additionally, cluster 1 also performed better than cluster 2 in the conception test. Lastly, educational implications were discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.90-97
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• 2006

In this paper, we present a cost-effective architecture of high-speed soft-decision Viterbi decoder for Multi-band OFDM(MB-OFDM) systems. In the design of modem for MB-OFDM systems, a parallel processing architecture is general]y used for the reliable hardware implementation, because the systems should support a very high-speed data rate of at most 480Mbps. A Viterbi decoder also should be designed by using a parallel processing structure and support a very high-speed data rate. Therefore, we present a optimized hardware architecture for 4-way parallel processing Viterbi decoder in this paper. In order to optimize the hardware of Viterbi decoder, we compare and analyze various ACS architectures and find the optimal one among them with respect to hardware complexity and operating frequency The Viterbi decoder with a optimal hardware architecture is designed and verified by using Verilog HDL, and synthesized into gate-level circuits with TSMC 0.13um library. In the synthesis results, we find that the Viterbi decoder contains about 280K gates and works properly at the speed required in MB-OFDM systems.

• Communications of Mathematical Education
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• v.27 no.2
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• pp.135-163
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• 2013

This study dealt with the measurements of the positive psychological experience of high school students in relation to mathematics learning by using PPE-M. The purpose of this study is to compare the positive psychology of the high school students based on the grade and gender variables. Measured data for the purpose of this study examined the difference between the gifted students and the general students through a t-test. In addition, differences were analyzed by grade and gender variables. And One-way ANOVA was conducted to see the difference according to the course variables. The difference between the two groups was meaningful in PPE-M total score. There was meaningful difference in all of 5 areas and 19 factors except for 4 factors (Insight, Honesty, Full with pride, and Achievement). However, there was no difference according to grade levels. The comparison between the gender in the ordinary students shows meaningful difference in 11 factors, not in 12 (Judgment, Insight, Honesty, Prudence, Modesty & Kindness, Gratitude & Happiness, Flow, Superiority feeling, Achievement, High pleasure, Full with pride, and Self-efficacy). Affiliation makes meaningful difference in 22 factors except for Honesty.

• Journal of Digital Convergence
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• v.18 no.8
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• pp.29-35
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• 2020

This study identified the impact of augmented reality advertising on attitude toward advertising and memory according to the type of presence and flow level. The presence (cognitive, emotional, media) and flow level (high vs. low) of the augmented reality(AR) advertising were set as independent variables and analyzed by Two-Way MANOVA. As a result of the research, first, the augmented reality advertising attitude was positive when the emotional presence and flow level were high. Second, when the flow level is high, the ARM such as product attribute information increases, but when the flow level is low, the evaluation-oriented GRM increases. Third, emotional presence increases GRM when the flow level is high, but ARM increases when the flow level is low. Fourth, the memory effect was low regardless of the flow level. In the future research, it would be desirable to produce augmented reality advertisements through virtual brands in the generalization of research.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.385-392
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• 2017

The aim of this study was to examine the image for dental hygienists and influence factor in academic high school students. A self-reported questionnaire was surveyed by 211 high school student in G area. the data were analyzed for frequency analysis, average, standard deviation, independent t-test, one-way ANOVA, pearson's correlation coefficient by using SPSS 21.0 program. In case of general high-school students, occupational and business images were higher significantly. The social images were higher significantly in case of having introduction or explanation for dental hygienists. In addition, the self-esteem showed significant differences depending on the oral condition. There were positive correlations among the occupational, business, personal, social images of dental hygienists and self-esteem. Multiple regression analysis showed that highest in occupational images.