• Journal of KIISE
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• v.43 no.11
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• pp.1245-1258
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• 2016

Cryptographic technologies providing confidentiality and integrity such as encryption algorithms and message authentication codes (MACs) are necessary for preventing security threats in the Internet of Things (IoT) where various kinds of devices are interconnected. As a number of encryption schemes that have passed security verification are not necessarily suitable for low-power and low-performance IoT devices, various lightweight cryptographic schemes have been proposed. However, a study of lightweight MACs is not sufficient in comparison to that of lightweight block ciphers. Therefore, in this paper, we reviewed various kinds of MACs for their classification and analysis and then, we presented a new way for future MAC development. We also implemented major MAC algorithms and performed experiments to investigate their performance degradation on low-end micro-controllers.

• The Journal of the Korea Contents Association
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• v.15 no.2
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• pp.292-300
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• 2015

This study was conducted to investigate weight control behavior and obesity stress of college women. The data were collected from September 7 to September 13 of 2013 and the subjects were 213 college women in C city of Gyoung-nam Province. The data were analyzed by SPSS 20.0 program using descriptive statistics, t-test, ANOVA, Scheffe's test. The score of obesity stress was moderate($18.26{\pm}5.66$). The level of obesity stress was affected by various general characteristics and weight control behavior characteristics including economic status(F=3.99, p=0.020), figure recognition(F=14.41, p<.001), satisfaction of body figure(F=15.88, p<.001), interest of weight control(F=4.82, p=.001), control of food amount(F=2.41, p=.050), body figure compulsion(F=24.06, p<.001), experience of dieting (F=6.04, p<.001), sleeping hours(t=2.10, p=.036), desired losing weight (F=10.47, p<.001). Therefore, it is necessary to be considered these variables during development of body weight control programs for college women.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.69-78
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• 2007

A Frequency synthesizer for T-DMB and mobile-DTV applications was designed using $0.18{\mu}m$ CMOS process with 1.8V supply. PMOS transistors were chosen for VCO core to reduce phase noise. The VCO range is 920MHz-2100MHz using switchable inductors, capacitors and varactors. Varactor biases that improve varactor acitance characteristics were minimized as two, and $K_{VCO}$(VCO gain) value was aintained by switchable varactor. Additionally, VCO was designed that VCO gain and the interval of VCO gain were maintained using VCO gain compensation logic. VCO, PFD, CP and LF were verified by Cadence Spectre, and divider was simulated using Matlab Simulink, ModelSim and HSPICE. VCO consumes 10mW power, and is 56.3% tuning range. VCO phase noise is -127dBc/Hz at 1MHz offset for 1.58GHz output frequency. Total power consumption of the frequency synthesizer is 18mW, and lock time is about $140{\mu}s$.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.61-73
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• 2020

Real-time location-sensing technology using location information collected from IoT devices is being applied for safety management purposes in many industries, such as ports. On the other hand, positional error is always present owing to the characteristics of GPS. Therefore, accident-risk detection algorithms must consider positional error. This paper proposes an methodology of calibration for falling object accident-risk-zone approach detection algorithm considering GPS errors. A probability density function was estimated, with positional error data collected from IoT devices as a probability variable. As a result of the verification, the algorithm showed a detection accuracy of 93% and 77%. Overall, the analysis results derived according to the GPS error level will be an important criterion for upgrading algorithms and real-time risk managements in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.858-865
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• 2006

A certificate that is issued by the certification authority can be revoked within the period of validity by various reasons such as the loss of private key, disqualification or the change in key. Therefore, the certificate status verification must precede prior to use Currently, the CRL or the OCSP methods are used in most cases. But the CRL system can't guarantee the present status of the certificate, and the OCSP generates heavy network traffic by checking or requesting certificate status in real-time using high-capacity messages. In this paper, we propose a system that requests the certificate verification by creating VDN for user identity information. Through this system, the certification authority will be able to guarantee the certificate's status in real-time, and solve the problem of the sewer and network overload by verifying and finding user identity information from VDN, Based on the results, we propose a real-time certificate status verification system which can improve the speed of the verification. We confirmed the improvement in speed by testing and comparing it with the existing methods.

• Korean Security Journal
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• no.23
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• pp.87-107
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• 2010

The purpose of this study is to examine the effects of customer aggression on the job stress and emotional burnout of security guards in casino. Investigating tools used questionnaire, the sampling was drawn from security guards at 6 casinos which had more than 30 security guards. To this study, the partisans of the study were 269 people. Data for creation for questionnaire is completely computed processing and using SPSS 15.0 Windows that is social studies scholastic mantle command program after imputed encoding according to each purpose. Analyzing techniques to use for analysis of data enforced technology figure analysis, factor analysis, reliability analysis, t-test, one-way ANOVA, multiple regression analysis. Through data analysis by such method and procedure, conclusion that gets in this research is as following. First, exposure that is difference that keep in mind partially as result that verify difference of aggression according to demographical features, job stress and emotional burnout that is security guard's in casino. Second, exposure that is difference that keep in mind as statistical as result that verify effect that customer aggression gets in job stress of security guards in casino. Third, exposure that is difference that keep in mind as statistical as result that verify effect that customer aggression gets in emotional burnout of security guards in casino.

• Journal of Christian Education in Korea
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• v.67
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• pp.117-156
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• 2021

This study was conducted in order to investigate the effect of interaction bewteen a Sense of Community and Marital Intimacy effect on learning participation motive in the church family ministry program. In this study, data from 607 people(male: 302, female: 305) nationwide churches and institutes participating in church family ministry program were collected as analysis targets. The produced results from this study are: First, Emotional connection, one of the Marital Intimacy, has meaningful effect (t=6.087, p<.001) on Continuous motivation, one of the learning participation motive. Second, Membership, one of the Sense of Community, has meaningful effect (t=3.343, p<.001) on Intrinsic motivation, one of the learning participation motive. Third, Influence, one of the Marital Intimacy, has meaningful effect (t=5.358, p<.001) on Extrinsic motivation, one of the learning participation motive.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.135-141
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• 2013

Subway in Korea, most of a metropolitan public transport use only worth ten million people a day floating population of wireless communication can be considered HOT SOPT. These three operators' 2G/3G/4G / Wi-Fi / T-DMB frequency and the number of services to co-exist, and the subway train passengers and subway party for operation and management of the communication network is also the co-subway passenger safety and for this service for the effects of mutual interference of whether the verification was necessary. This research and testing different frequency / communication interference between services and testing to determine whether, through the subway authorities and mobile operators in each frequency-specific interaction check and there is no interference to the safety and quality of subway passengers communication services that can be verified as the data was found. The verification methods in the metro area, not just from one region to determine whether the interference with a common verification methods can be applied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.366-372
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• 2018

The purpose of this study was to investigate the effects of educational evaluation with the application of flipped learning on undergraduate students' self-directed learning ability (cognitive domains, motive domains, conductive domains) and cognitive learning competency (knowledge and thought, creation, problem solving). An educational evaluation class, which applied flipped learning designed on the basis of pre-class, in-class, and post-class, was taught to 57 undergraduate students for twelve of the sixteen weeks of a semester. It was held each week on Thursdays for two (Ed- I don't understand 'for two'). The study results showed that, applying the flipped learning educational education class for undergraduate students improved self-directed learning ability (motivation domains, behavior domains) and cognitive learning competence (higher order thinking, metacognition, creativity tendency, problem-solving process). This study provides meaningful suggestions on exploring instructional design and effective teaching and learning methods applied to flipped learning.

• Journal of The Korean Association of Information Education
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• v.15 no.2
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• pp.189-199
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• 2011

The purpose of this study is to verify the effects of the advance organizer in programming class on elementary school students' logical thinking ability and self-efficacy. We developed our teaching-learning materials of programming for this purpose, Further, they are applied to the elementary school, and their effects are analyzed. Fourth grade students in elementary school were selected for the experiments of this study, For comparison, they were divided into a control group who taught by a traditional programming teaching method and an experimental group who taught by our advance organizer programming class. As a result, through before-and-after t-verifications performed on the experimental group and the control group respectively, we found statically significant differences between the two groups, and the effectiveness of our new programming teaching method was proved in both learner's self-efficacy and logical thinking ability.