• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.612-620
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• 2017

Relay coordination in power system is a complex problem and so far, meta-heuristic algorithms and other methods as an alternative approach may not properly deal with large scale relay coordination due to their huge time consuming computation. In some cases the relay coordination could be unachievable. As the urgency for a proper approach is essential, in this paper an innovative and simple relay coordination method is introduced that is able to be applied on optimization algorithms for relay protection coordination. The objective function equation of operating time of relays are divided into two separate functions with less constraints. As the analytical results show here, this equivalent method has a remarkable speed with high accuracy to coordinate directional relays. Two distribution systems including directional overcurrent relays are studied in DigSILENT software and the collected data are examined in MATLAB. The relay settings of this method are compared with particle swarm optimization and genetic algorithm. The analytical results show the correctness of this mathematical and practical approach. This fast coordination method has a proper velocity of convergence with low iteration that can be used in large scale systems in practice and also to provide a feasible solution for protection coordination in smart grids as online or offline protection coordination.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.71
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• pp.217-243
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• 2016

As the rapid development of IT and the internet changed the trading method from the traditional offline transaction into the online e-Trading, the international documentation standards, the eUCP and the domestic laws and legislations have been established, adapting to the new e-Trading environment. This study was conducted to analyze the factors which affect the use of uTradeHub on the domestic trading companies and trade-related organizations and suggest how to activate e-Trading. To do this, classify the users into the enterprises and the trade-related organizations, set up the hypothesis of the study with the measurement variables of the user convenience, the new service, the system suitability and the legislation environment and carry out a survey targeting the trading companies and the trade-related offices to do an actual proof analysis. The analysis was performed by using the statistical program, SPSS IBM22.0, and the study hypothesis was tested by the multiple regression analysis methodology. The test result showed that the trading companies set a high value on the user convenience, the new service and the legislation environment of uTradeHub, meanwhile the trade-related organizations regarded the system security and reliability, the user convenience and the legislation environment as the major affecting factor on the use of uTradeHub.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1066-1071
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• 2007

This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.

• Journal of Engineering Education Research
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• v.23 no.4
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• pp.22-27
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• 2020

We propose and execute an introductory engineering course for investigating the history of technology and the philosophy of technology. Soft engineering, to explore proper technology and appropriate ways of exercising engineering, has been explored. Creative cases for technology are presented following the most creative, successful periods-the ancient greece, the Renaissance and Silicon Valley era. Ancient greek technology has been investigated in terms of "techne" with the origin of technology and/or art, and their equivalences. The Renaissance period has been investigated in terms of "Uomo universale (polymath)" with Firenze geniuses. The successful drives for the Silicon Valley creativeness have been investigated following "entrepreneurship". To overcome the difficult goal to grasp course subject-technology issues, we take a stance as a tourist guide and tourists utilizing offline onsite experiences and online informations. Categorized course materials are surveyed at the beginning of each period and presented following the preferences of the students to maintain the students' interests. Team efforts including group discussions and project executions have been encouraged to seek the aspects of creativeness and/or technology. This paper summarizes the 3-lecture experiences over 2 years for Korean students and/or foreign students conducted at Pusan National University.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.238-246
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• 2008

This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.34-44
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• 2020

The purpose of this study is to identify the structural causal relationship among the psychological burnouts, job engagement and turnover intentions influenced by perfectionism of flight attendants to reestablish concepts by approaching their psychological difficulties and establish strategies for effective human resource management for airlines. The period of data collection was from August 1st to September 1st, 2019 by using online and offline surveys. A total of 208 answered surveys were used for analysis. The major results of this study showed that first, the perfectionism of flight attendants had an effect on psychological burn-outs, supporting Hypothesis 1. Second, the psychological burnout of flight attendants showed to have a negative (-) meaningful effect on their job engagement. Third, the psychological burnout of flight attendants showed to have a positive (+) meaningful effect on their turn-over intentions. Lastly, the job engagement of flight attendants had a negative (-) effect on their turnover intentions.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.187-195
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• 2019

The purpose of this study is to analyze the adoption of Kakao Bank in terms of benefits (functional, social, experiential, economic benefits) and differentiated services (customization and service diversity) considering service types. Benefits are personal value consumers attach to the product or service attributes and, therefore, more important than attributes of service itself when using Kakao Bank in the internet based environment. Data was collected using an online and offline survey of 131 Kakao Bank users and analyzed the data using structural equation model (SEM). The results of empirical analysis using SmartPLS show that functional benefit, experiential benefit, and customization are significantly related to the user's satisfaction, but economic benefits, social benefit, and service variety are not. Customer's satisfaction are also showed significantly to be related to the all types of Kakao Bank usage(balance check, transfer, and other services). This study has the significance in that it examines the user's satisfaction and usage of Kakao Bank in terms of benefits and differentiated services while other studies analyzed banking services focusing on the attributes of banking channel itself.

• Journal of Distribution Science
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• v.16 no.8
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• pp.39-50
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• 2018

Purpose - The ultimate purpose of this research is to analyze the influence of personal disposition on shopping value and behavioral intention by expanding the theory of planned behavior (TPB). Research design, data, and methodology - An attempt was made to examine the effects of personal disposition (reflecting duty-free shop characteristics) on three selective actions of consumers - compulsive buying, variety seeking, and price sensitivity. We conducted a questionnaire survey with the users of airport duty-free shops, downtown duty-free shops (offline), and online duty-free shops. In total, 410 copies of the questionnaire were analyzed using a structural equation model. Results - According to the results, compulsive buying, variety seeking, and price sensitivity significantly affected shopping value. Shopping value and subjective norms both had significant effects on attitude, the major variable in the TPB, and attitude had the greatest effect on behavioral intention, followed by subjective norms and perceived behavioral control in descending order. Conclusions - This study has academic implications in that it extends the existing theories of planned behavior and applies it to consumer characteristics and shopping value. It has practical implications as well in that it provides basic data that can be used to establish concrete marketing strategies for duty-free shop owners targeting segmented markets by closely examining customer desires.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2674-2697
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• 2019

Identity authentication is a crucial line of defense for network security, and passwords are still the mainstream of identity authentication. So far trawling password attacking has been extensively studied, but the research related with personal information is always sporadic. Probabilistic context-free grammar (PCFG) and Markov chain-based models perform greatly well in trawling guessing. In this paper we propose a systematic targeted attacking model based on structure partition and string reorganization by migrating the above two models to targeted attacking, denoted as TG-SPSR. In structure partition phase, besides dividing passwords to basic structure similar to PCFG, we additionally define a trajectory-based keyboard pattern in the basic grammar and introduce index bits to accurately characterize the position of special characters. Moreover, we also construct a BiLSTM recurrent neural network classifier to characterize the behavior of password reuse and modification after defining nine kinds of modification rules. Extensive experimental results indicate that in online attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 275%, and respectively outperforms its foremost counterparts, Personal-PCFG, TarGuess-I, by about 70% and 19%; In offline attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 90%, outperforms Personal-PCFG and TarGuess-I by 85% and 30%, respectively.

• International Journal of Contents
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• v.18 no.3
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• pp.21-33
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• 2022

Previous research has provided inconsistent findings as to whether socially (in)competent individuals benefit from social networking sites (SNSs) use. Based on the rich-get-richer model, some studies have shown that socially competent individuals expand their existing networks even further via SNSs use. Based on the poor-get-richer model, other studies have shown that those with poor social skills can achieve beneficiary outcomes from SNSs use by overcoming their deficient social resources of offline environments. The present study is devised to add evidence regarding how and why social skills are related to SNSs use. To this end, we tested the relationships between social competence and three types of Facebook communication activities: interaction, self-presentation, and passive observation. Further, drawing on the social cognitive theory, the mediating role of outcome expectancy in the relationship between social competence and Facebook communication activities was examined. Using an online survey in South Korea (N = 708), it was found that individuals with higher social competence were more likely than those with lower social competence to engage in interaction, self-presentation, passive observation on Facebook. Moreover, these relationships were mediated by outcome expectancy that the desired social outcomes could be achieved as a result of Facebook use.