• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.5
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• pp.423-431
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• 2001

This paper proposes a new active common-mode voltage damper circuit that is capable of suppressing a common-mode voltage produced in the PWM VSI-fed induction motor drives. The new active common mode voltage damper is consists of a four-level half-bridge Inverter and a common mode transformer with a blocking capacitor. In order to reduce the common mode voltage and high frequency leakage current the active common mode damper applies to the PWM inverter system the compensated voltage of which the amplitude is the same as the common mode voltage and of which the polarity is opposite to the common mode voltage. Simulated using P-SPICE and experimental results show that common-mode voltage damper makes contributions to reducing a high frequency leakage current and common-mode voltage.

• The Journal of the Korea Contents Association
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• v.19 no.7
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• pp.36-46
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• 2019

If stock market is efficient, any well-devised trading rule can't consistently outperform the average stock market returns. This study aims to verify whether the strategy based on bid-ask volume information can beat the stock market. I suggested a day trading strategy using order imbalance indicator and empirically analyzed its profitability with the KOSPI 200 index futures data from 2001 to 2018. Entry rules are as follows: If BSI is over 50%, enter buy order, otherwise enter sell order, assuming that stock price rises after BSI is over 50% and stock price falls after BSI is less than 50%. The empirical results showed that the suggested trading strategy generated very high trading profit, that is, its annual return runs to minimum 71% per annum even after the transaction costs. The profit was generated consistently during 18 years. This study also improved the suggested trading strategy applying the genetic algorithm, which may help the market practitioners who trade the KOSPI 200 index futures.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.139-146
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• 2019

In this study, we examined how consumers who experience HMD virtual reality advertising differ in their ad attitudes and memory effects according to Presence (cognitive presence, emotional presence, media presence) and engagement level. Particularly, in the case of memory effect, the information that the user memorizes through the advertising is divided into "Attribute-Related Memory (ARM)" and "Global-Related Memory (GRM)" Respectively. First, the attitudes toward HMD based virtual reality ads are positive regardless of the type of presence. Second, in the virtual reality advertising, if the level of engagement is low, ARM that memorizes the information of the product attribute is increased, whereas if the level of engagement is high, the GRM which is the memory of the attitude-based evaluation information about the product is increased appear. Third, if cognitive presence and media presence are low, then ARM is more memorable than GRM.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.101-111
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• 2019

This study was to examine association between working memory and social cognitive ability, and the influence of story-use on social cognitive ability. To this end, this study measured working memory(via n-back), and randomly assigned 82 participants into three groups(5th level intentionality, 3rd-level intentionality, and exposition conditions), and then compared the accuracy of perspective taking and emotion recognition(RMET: Reading Minds in the Eyes Test) as social cognitive ability. The results suggested that perspective taking accuracy was significantly associated with working memory capacity, whereas emotion recognition accuracy was not. Contrary to the hypothesis, perspective taking in the 5th-level intentionality story group were significantly lower than those in the 3rd-level intentionality story group. Emotions recognition accuracy was not significantly different among the three groups. Overall, this study produced inconsistent results, which has been discussed in terms of theory and methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.110-117
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• 2018

Recently, as weapon systems have become more complex and multi-functional, the difficulty of the operation and maintenance of weapon systems in the military have become increasingly difficult. On the other hand, the service period of operations and maintenance workers who perform operations and maintenance has been shortened, and the skill of system operation and maintenance has been lowered. This complexity and multi-functionality of equipment cause malfunctions and errors of users and maintenance personnel, and degradation of the reliability affects availability and combat readiness. In addition, life cycle costs have been gradually increasing. Therefore, I would like to suggest an improvement plan of the design of weapon systems and ILS (Integrated Logistics Support) in order to examine the implications of failure in the military. The weapon system is operated in the ROK Navy. Data from 730 cases of failure of weapon systems was collected, and analyzed. The results of the analysis are classified into failures that can be prevented in advance and failures that cannot be prevented. This shows the portion of preventable failures in weapon systems and proposes measures to minimize failures.

• Convergence Security Journal
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• v.21 no.1
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• pp.33-44
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• 2021

Data outsourcing utilizing the Cloud faces a problem of the third-party exposure, modulation, and reliability for the provided computational delegation results. In order to solve those problematic security issues, homomorphic encryption(HE) which executes calculation and analysis on encrypted data becomes popular. By extension, a new type of HE with a authentication functionality, homomorphic authenticated encryption(HAE) is suggested. However, a research on the HAE is on the initial stage. Furthermore, based on a message authenticated scheme with HE, the method and analysis to design is still absent. This paper aims to analyze an HAE, with a generic combination of a message authenticated scheme and a HE, known as "Encrypt with Authentication". Following a series of analysis, we show that by adopting a unforgeable message authenticated scheme, the generically constructed HAE demonstrated an unforgeability as well. Though, a strong unforgeability is not the case. This paper concludes that although indistinguishable HE can be applied to design the HAE, a security issue on the possibility of indistinguishability is still not satisfied.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.305-317
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• 2021

By examining the experience of residential child care staffs, this study explored the multifaceted aspects of inclusive care and discussed the direction of successful inclusive education implementation in residential child care facilities. Interviews were conducted with 10 care staffs experienced inclusive education at residential child care facilities, and qualitative case study method was used to analyze transcribing data. Care staffs were reluctant to carry out inclusive education. They felt guilty due to not enough care either for disabled or non-disabled children in the process of adapting to inclusive education. They were calling for immediate communication channels to get the necessary support on time. They also recognized needs for professional education for care staffs regarding care of disabled children, and to dispatch special education teachers. It was found that all participants in the study disagreed on three-shift policy. Lastly, the support measures according to the multifaceted aspects of inclusive care in residential child care facilities were discussed.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.348-352
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• 2011

In this research, we have synthesized new pendant-type polyurethane polymers by introducing various chromophores with stilbene derivatives in the side-chain of the polymer backbone. The Stilbene monomers, N,N-bis(2-hydroxyethyl) amino-4'-cyanostilbene, N,N-bis(2-hydroxyethyl)amino-4'-methoxy stilbene, N,N-bis(2-hydroxyethyl)amino-4'-acetylstilbene, and N,N-bis(2-hydroxyethyl) amino stilbene, were synthesized by Wittig reaction. Another stilbene monomer, N,N-bis(2-hydroxyethyl)amino-4'-nitrostilbene, was synthesized by Knoevenagel condensation. By the measurement of UV-Vis absorption and Photoluminescence (PL) spectrum, we found that introduction of the electron-withdrawing group as a substituent shifts both UV-Vis and PL spectra to longer wavelength, and the introduction of the electron-donating group results in blue-shift of the spectrum. In case of polymer with $NO_2$ group as a substituent, PL is quenched.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.497-505
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• 2020

As social interest in emotional labor grows, there are many related studies in progress in recent times. However most of the studies are focused on preventing harmful effects of emotional labor or seeking effective follow-up measures from the service provider's point of view. For this reason, with focusing on the bank teller service which is one of most representative face-to-face emotional labor, this study was progressed to suggest improvement measures by identifying and analyzing the current status of visual installations at the work space for awareness improvement of emotional labor from the customer's point of view. To this end, after a prior study, an field survey of 10 banks in the first financial sector was conducted to draw out problems and finally propose improvement directions with four aspects in link with the problems presented. This study is expected to have meaning in terms of securing diversity in emotional labor related research.

• Knowledge Management Research
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• v.22 no.2
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• pp.55-76
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• 2021

The real estate market is a representative imperfectly competitive market. Real estate information is characterized by being collected and utilized in a closed environment, and market participants have to pay a lot of time, effort, and costs to acquire such information. Korea's real estate public data is increasing year by year, but it is scattered by relevant ministries. So it is difficult to search and analyze, and the level of development of the industry using it is low. In the recent 4th industrial revolution, the proptech industry has developed as an industry to efficiently provide necessary information to the real estate market. In this study, based on the case of major companies in the real estate platform field among proptech companies, we looked at the types of information provided to users, and on the contrary, explored ways to utilize the data collected from users. The results of this study are expected to provide theoretical and practical implications for ways to reduce information asymmetry in the real estate market and contribute to the development of the real estate industry.