• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.405-408
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• 2002

Cluster is the cost-effective parallel processing environment, and consists of the off-the-shelf computers connected by the computer networks. The characteristics of cluster are the node heterogeneity, the variety of node load, and the variety of network load. Because these characteristics influence the performance of parallel program executions, the load sharing for cluster is important, and by using the proper load sharing strategy, we can reduce the execution time of parallel programs. In this paper, we propose modified GSS algorithm, aGSS. In the proposed load sharing algorithms aGSS, the size of tasks are decided using the BogoMTPS of node. From the result of out experiments, we conclude that the proposed aGSS algorithm is effective in the heterogeneous cluster.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1152-1162
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• 2016

The unequal impedances of the interconnecting cables between paralleled inverters in the island mode of microgrids cause inaccurate reactive power sharing when the traditional droop control is used. Many studies in the literature adopt low speed communications between the inverters and the central control unit to overcome this problem. However, the losses of this communication link can be very detrimental to the performance of the controller. This paper proposes an improved reactive power-sharing control method. It employs infrequent measurements of the voltage at the point of common coupling (PCC) to estimate the output impedance between the inverters and the PCC and then readjust the voltage droop controller gains accordingly. The controller then reverts to being a traditional droop controller using the newly calculated gains. This increases the immunity of the controller against any losses in the communication links between the central control unit and the inverters. The capability of the proposed control method has been demonstrated by simulation and experimental results using a laboratory scale microgrid.

• ETRI Journal
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• v.38 no.5
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• pp.952-961
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• 2016

In this paper, we study a spectrum sharing network (SSN) where a spectrum sharing device (SSD) coexists with multiple wireless communication systems (WCSs) in the same channel. The SSD can operate with either a duty cycle (DC) channel access mechanism or a listen-before-talk (LBT) channel access mechanism, whereas WCSs operate with an LBT mechanism. An opportunistic channel selection scheme for the SSD in the SSN is first proposed to minimize the outage probability. The optimal data transmission time for the DC-based SSD is derived to further improve the outage probability. We also derive the exact and closed-form outage probability of the proposed channel selection in the SSN by assuming that the number of WCSs operating in each channel is uniformly distributed. The simulation results show that the proposed channel selection scheme outperforms other channel selection schemes. It was also observed that a DC-based SSD with an optimal data transmission time provides a better outage performance than an LBT-based SSD. As the number of available channels increases, the channel selection scheme plays an important role in minimizing the outage probability of the SSNs.

• Journal of muscle and joint health
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• v.30 no.1
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• pp.48-57
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• 2023

Purpose: The purpose of this study was to examine nurses' critical thinking disposition and knowledge sharing activity and professional work environment on clinical decision-making ability. Methods: The data collection period for this study was from May 24 to May 31, 2021. The data were collected from 167 nurses who consented to participate in this study and have worked for more than one year at general hospital in Seoul. The data were analyzed using the SPSS/WIN 25.0 program. Results: A significant positive correlation was found between clinical decision-making ability and critical thinking disposition, knowledge sharing activity, and a professional work environment. Critical thinking disposition (β=.32, p<.001), knowledge sharing activitiy (β=.24, p=.002) and professional work environment (β=.20, p=.006) had a significant effect on clinical decision-making ability. These factors explained 35.5% of clinical decision-making ability (F=24.22, p<.001). Conclusion: Therefore, in order to develop the critical thinking disposition of nurses, development of systematic educational programs and strategies for practical application are needed. Through this, nurses can improve the professional decision-making ability and clinical performance ability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.5
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• pp.1634-1652
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• 2022

Due to the increasing need for data sharing in the age of big data, how to achieve data access control and implement user permission revocation in the blockchain environment becomes an urgent problem. To solve the above problems, we propose a novel blockchain-based data sharing scheme (BDSS) with fine-grained access control and permission revocation in this paper, which regards the medical environment as the application scenario. In this scheme, we separate the public part and private part of the electronic medical record (EMR). Then, we use symmetric searchable encryption (SSE) technology to encrypt these two parts separately, and use attribute-based encryption (ABE) technology to encrypt symmetric keys which used in SSE technology separately. This guarantees better fine-grained access control and makes patients to share data at ease. In addition, we design a mechanism for EMR permission grant and revocation so that hospital can verify attribute set to determine whether to grant and revoke access permission through blockchain, so it is no longer necessary for ciphertext re-encryption and key update. Finally, security analysis, security proof and performance evaluation demonstrate that the proposed scheme is safe and effective in practical applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2328-2339
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• 1994

The PBS(Partial Buffer Sharing) space priority mechanism is one of priority control methods which may improve the performance of a single server queueing system when mixed traffic with different performance requirements is applied to the system. This paper analyzes the cell loss behavior of PBS assuming loss sensitive traffic and delay sensitive traffic are applied to the system. To derive the successive cell loss probabilities. which are an important performance measure of realtime traffic, we develop a recursive algorithm. Performance results show the successive cell loss probabilities obtained by our method are lager than the probabilities derived from an independent cell loss assumption. These results may indicate the limitation of PBS for realtime traffic and the increase of the admissible load with the criterion of quality of service.

• The Journal of Information Systems
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• v.21 no.1
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• pp.19-46
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• 2012

This paper classifies the success factors of collaboration system in the shipbuilding industry. We propose the structural model that identifies the relationship between the success factors and organizational performance. To test empirically the relationship between the factors, we developed the measurement of each factors. This paper has examined the relationship between the independent variables and the mediating variables, also has examined the relationship between the parameters and a final dependent variable. The independent variables are as follows, (1) quality of system including reliability, flexibility, and accessibility, (2) the quality of information including contents, expressiveness, and (3) the partner relationship including the information sharing and the compatibility of strategies. The mediating variables are user involvement, parter trust, and user satisfaction. The final dependent variable is business performance. The hypotheses test proved that the system quality significantly affect user satisfaction, the information quality positively influence on the user participation, and the information sharing and strategic fit of partner relationship positively affect partner trust. Also, the user participation and partner trust significantly affect user satisfaction. Finally, the user participation, user satisfaction, and partner trust have a decisive effect on the organizational performance. The results of hypothesis test verified that the quality of information and system, also partner relationship are important to operate successfully the collaboration system in the shipbuilding industry. Also, the mediating variables are important to explain the structural relationship between the independent variables and organizational performance.

• Knowledge Management Research
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• v.5 no.1
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• pp.19-38
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• 2004

The present paper examines the effect of "community of learning" factors as well as learning and contextual factors on the e-learning performance empirically. The concept of community of learning, which was derived from community of practice, has not been emphasized in previous studies on e-learning. Data were collected from 226 people who had experienced e-learning and multiple regression analysis was used to analyze the data. The results are as follows; First, learning motivation and appropriateness of learning contents, ease of system use, and knowledge sharing have a positive effect on learner's satisfaction. Whereas, learning motivation, appropriateness of learning contents, ease of system use, knowledge sharing, and activated communication are appeared to affect the ability of performing tasks significantly.

• Progress in Superconductivity
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• v.10 no.2
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• pp.108-115
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• 2009

As a participant taking part in the ITER TF conductor R&D program, we developed two toroidal field conductors with variations of conduit thickness resulting in the different void fraction of the conductors. The estimated void fractions of the conductors are 31% and 33%. In this paper we present the details of the TF conductor development and performance test results of them carried out by the measurement of current sharing temperature under cyclic loading. Regarding the conductor development, the internal-Sn-processed $Nb_3Sn$ strand characteristics, strand cabling, twist pitch and characteristics of the conduit materials are presented. For the understanding of the conductor design and performance, the conductor test results are presented and the effect of the conductor design parameters such as void fraction and twist pitch is discussed based on the results.

• Journal of Power Electronics
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• v.13 no.5
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• pp.787-797
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• 2013

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.