• Journal of Power Electronics
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• v.16 no.6
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• pp.2315-2326
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• 2016

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.20-28
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• 2024

The purpose of this study is to investigate the impact of negative emotions on the intention to share negative experiences caused by unruly passengers on flights. 163 questionnaires were collected and an SEM model was used to measure the relationship between passengers' negative emotions and sharing intentions. We empirically analyzed the impact of unruly passenger behavior on social media sharing intention through negative emotions, airline trust, and satisfaction with service recovery. Theoretically, we established a clear causal relationship between these variables. The results of this study shed light on the importance of developing a sustainable service strategy for passengers by analyzing the impact of negative emotions and sharing intentions. Based on our findings, we recognized that airlines should respond to disruptive behavior while understanding the negative emotional feelings of surrounding passengers. Therefore, this study strongly recommends that airlines should respond appropriately to in-flight disruptive behavior and ensure that passengers' negative emotions do not damage the overall reputation and image of the airline.

• Journal of Korean Library and Information Science Society
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• v.40 no.2
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• pp.287-310
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• 2009

This paper strives to shed a new light on current academic resource sharing initiatives of both Korea Research Foundation(KRF) and Korea Science and Engineering Foundation(KOSEF), and seeks the measure to administer information resource effectively for a unified organization, which will launch soon, through the comparison and scrutiny, and analyses of strength and weakness on current projects. It first of all attempts to draw outcomes and suggestions on the basis of issues and implications identified through the exhaustive as-is analyses in the aspects of management, service, and infrastructure of academic resource sharing initiatives carried out by each foundations. The unification of projects and information systems are discussed in two aspects, as viewed each significant measures, that is, 1) an organizational aspect in terms to develop a new academic and research information service through the unification of operation systems related to information service project of each foundation; 2) An Initiative toward the integrated service via the unification of scattered individual unit systems in each foundation.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1658-1671
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• 2017

To address the inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids (MGs) with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on the active compensation of circulating voltage drops is proposed in this paper. Using the proposed strategy, reactive power and harmonic currents are shared accurately and proportionally without knowledge of the feeder impedances. Since the proposed local controller consists of two well-separated fundamental and harmonic voltage control branches, the reactive power and harmonic currents can be independently shared without having a remarkable effect on the amplitude or quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminals of the units. In addition, accurate load sharing can also be attained when the plug-and-play performance of DGs and various loading conditions are applied to MGs. The effects of communication failures and latency on the performance of the proposed strategy are also explored. The design process of the proposed control system is presented in detail and comprehensive simulation studies on a three-phase MG are provided to validate the effectiveness of the proposed control method.

• Journal of Intelligence and Information Systems
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• v.27 no.3
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• pp.1-27
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• 2021

The entire tourism industry is being hit hard by the COVID-19 as a global pandemic. Accommodation sharing services such as Airbnb, which have recently expanded due to the spread of the sharing economy, are particularly affected by the pandemic because transactions are made based on trust and communication between consumer and supplier. As the pandemic situation changes individuals' perceptions and behavior of travel, strategies for the recovery of the tourism industry have been discussed. However, since most studies present macro strategies in terms of traditional lodging providers and the government, there is a significant lack of discussion on differentiated pandemic response strategies considering the peculiarity of the sharing economy centered on peer-to-peer transactions. This study discusses the marketing strategy for individual hosts of Airbnb during COVID-19. We empirically analyze the effect of changes in listing descriptions posted by the Airbnb hosts on listing performance after COVID-19 was outbroken. We extract nine aspects described in the listing descriptions using the Attention-Based Aspect Extraction model, which is a deep learning-based aspect extraction method. We model the effect of aspect changes on listing performance after the COVID-19 by observing the frequency of each aspect appeared in the text. In addition, we compare those effects across the types of Airbnb listing. Through this, this study presents an idea for a pandemic crisis response strategy that individual service providers of accommodation sharing services can take depending on the listing type.

• Asia pacific journal of information systems
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• v.14 no.3
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• pp.57-75
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• 2004

The knowledge management is increasingly an important strategic weapon for sustaining competitive advantage of firms. Firms are undertaking knowledge management initiatives and making significant investments. However, there is relatively little empirical support for the impact of knowledge management on performance of firms. Understanding of the impact of knowledge management, this paper explores how knowledge management strategy influences firms' market value. We examine this issue using event study methodology and evaluate the cumulative abnormal returns for knowledge management strategy announced by firms from 1998 to 2002. The results show that firms' announcements of knowledge management strategy are positively related with firms' market value. Specially, dynamic style-which emphasizes both (i) knowledge reusability through information technologies and (ii) knowledge sharing through informal discussions among employees-has higher performance. This outcome presents empirical support to argument that the emphasis on both tacit and explicit knowledge results in better market value.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.1
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• pp.133-152
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• 2009

This paper analyze the fee structures of digital music contents and the revenue sharing ratios that are now on-going debates in Korean digital contents industry. Especially we consider Korean situation where copyrighters and telecom companies have conflict of interest. We found two major results. First, the choice between the flat rate scheme and the usage-based rate scheme is not important to telecom companies and copyrighters. The important thing is that copyrighters should decide the revenue sharing ratio and given that telecom companies should decide the retail price. Consequently, this way can lead to win-win solutions between them. Second, the flat rate scheme affects the relationship between consumers and telecom companies. Under the flat rate scheme, telecom companies have more benefits than consumers. In the vertical integrated structure, particularly, this tendency is more severe.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.138-140
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• 2018

Parallel distributed generators (DGs) in the islanded microgrid are generally operated autonomously by means of the droop control scheme. However, the traditional droop control methods which use the P-${\omega}$ and Q-E curve to share power between DGs are still concerned to improve the accuracy of reactive power sharing. Moreover, the uncontrolled harmonic power reduces the point of common coupling (PCC) voltage quality and microgrid stability. In order to solve these problems, this paper proposes an enhanced PCC harmonic control strategy and an improved reactive power sharing control scheme. Based on the low bandwidth communications, a secondary control is implemented with both central controller and local controller. The effectiveness of the proposed control scheme is analyzed through the simulation.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.120-121
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• 2017

This paper proposes an enhanced distributed generation (DG) unit with an adaptive virtual impedance control approach in order to address the inaccurate reactive power sharing problem. The proposed method can adaptively regulate the DG virtual impedance, and the effect of the mismatch in feeder impedances is compensated to share the reactive power accurately. The proposed control strategy is fully distributed and the need for the microgrid central controller is eliminated. Furthermore, the proposed method can be directly implemented without requirement of pre-knowledge of the feeder impedances. Simulations are performed to validate the effectiveness of the proposed control approach.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.629-630
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• 2015

'Sabine Pass Liquefaction Project (SPL Project)', a case study in this report, is the first construction project of a U.S. liquefaction facility for shale gas export overseas. This study analyzes the SPL Project to give understanding and a guideline to Korean EPC companies by benchmarking about effective risk-sharing strategies on EPC contracts. This study consists of three parts. The first summarizes the liquefaction process adopted on the SPL Project, named the 'ConocoPhillips Optimized Cascade Process', and compares it with other competitive liquefaction processes. The second introduces the unique features of the SPL EPC contract by comparing it with two other EPC forms of contracts: a FIDIC Silver Book for onshore plant projects and a contract of an offshore oil production (FPSO) project. The third focuses on the complexity of project financing (PF), especially lenders control and impact on the EPC contract such as covenant provisions to constrain variations and changes on the EPC Contract. From these conclusions, it is anticipated that this case study can provide a guideline for successful performance of Korean EPC contractors overseas.