• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.632-639
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• 2011

Searching distributed resource efficiently is very important in distributed computing, cloud computing environment. Distributed resource searching may have system overheads and take much time in proportion to the searching number, because distributed resource searching has to circuit many peers for searching information. The open-source community project JXTA defines an open set of standard protocols for ad hoc, pervasive, peer-to-peer computing as a common platform for developing a wide variety of decentralized network applications. In this paper, we proposed peer search algorithm based on JXTA-Sim. original JXTA peer searching algorithm selected a loosely-consistent DHT. Our Lookup algorithm decreases message number of WALK_LOOKUP and reduce the network system overload, and we make a result of same performance both original algorithm and our proposed algorithm.

• Journal of Information Technology Services
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• v.15 no.1
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• pp.211-226
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• 2016

Most of the SNS users argue that they feel techno-stress or digital fatigue when they use SNS. As the relationships in the SNS expand, users may feel work overload, digital fatigue, and techno-stress which are caused by the time and effort for the retaining the existing relationships established via SNS. The SNS activities require users' time and effort to update their profiles and the current news of them, responding to online friends' contents. Thus, more relationships they have, more stress they can feel. This study tries to examine the key factors that can affect subjective well-being of individuals in Social Network Service (SNS) usage. Therefore, this study, based on the previous literature, investigates what the sources of SNS stress are and how SNS stress and flow affect subjective well-being of SNS users. Major findings of this study from an empirical analysis with 201 SNS user respondents who have accessed SNS at least one time within one month are as follows. First, perceived opportunity cost and reputation recognition in SNS usage were found to have significant effects on negative emotion. Second, individual's flow in SNS was significantly affected by challenges and interactions, and had a significant impact on positive emotion. However, SNS users' flow did not show a positive relationship with their satisfaction of life. This study contributes to the expansion of theoretical discussion about the effect of individual's SNS usage on quality of life in validating whether SNS usage can bring individuals subjective well-being. Implications of the study findings and future research directions are also discussed.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.77-85
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• 2003

The conversion into a new Local Area Network (LAN) environment without clear analysis of the problems with the conventional LAN environment nay bring about some improvement of performance, but in general, the result would not be as good as expected. Besides, in case new traffic or application programs are added In the near future, traffic overload similar to the past may incur. Therefore, the conversion into a new LAN environment should not only relieve the problems with the conventional environment but also be able to cope with future expansion of the network flexibly. In the present paper, in view of the above, the problems with protocols and traffic that may occur in the Bus-structured 10/100 Mbps shared Ethernet that has been widely used by many institutions are reviewed, and as a case study whether such conversion into a new LAN environment in order to increase the efficiency in the operation, management, and utilization of the network would be proper for the actual operational environment is implemented, and the results are analyzed.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.662-671
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• 2012

Plug-in hybrid electric vehicles (PHEVs) will be widely used in future transportation systems to reduce oil fuel consumption. Therefore, the electrical energy demand will be increased due to the charging of a large number of vehicles. Without intelligent control strategies, the charging process can easily overload the electricity grid at peak hours. In this paper, we consider a smart charging and discharging process for multiple PHEVs in a building's garage to optimize the energy consumption profile of the building. We formulate a centralized optimization problem in which the building controller or planner aims to minimize the square Euclidean distance between the instantaneous energy demand and the average demand of the building by controlling the charging and discharging schedules of PHEVs (or 'users'). The PHEVs' batteries will be charged during low-demand periods and discharged during high-demand periods in order to reduce the peak load of the building. In a decentralized system, we design an energy cost-sharing model and apply a non-cooperative approach to formulate an energy charging and discharging scheduling game, in which the players are the users, their strategies are the battery charging and discharging schedules, and the utility function of each user is defined as the negative total energy payment to the building. Based on the game theory setup, we also propose a distributed algorithm in which each PHEV independently selects its best strategy to maximize the utility function. The PHEVs update the building planner with their energy charging and discharging schedules. We also show that the PHEV owners will have an incentive to participate in the energy charging and discharging game. Simulation results verify that the proposed distributed algorithm will minimize the peak load and the total energy cost simultaneously.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.3
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• pp.120-131
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• 2017

Recent studies have suggested that providing in-vehicle feedback on various driving behaviors promote eco-friendly driving behaviors. However, there was relatively little interest in cognitive overload that can be caused by the provision of information. Thus, the goal of this study was to investigate the relative effects of two types of feedback(visual feedback vs. visual-auditory feedback) to increase eco-driving performance while minimizing driving workload. Also, in this study, the complexity of the driving task was distinguished (secondary vs. tertiary task) in order to reflect the actual driving situation. The study adopted a counterbalancing design in which the two feedback types were delivered in a different order under the two different task conditions. Results showed that providing the visual-auditory feedback was more effective than the visual only feedback in both promoting eco-friendly driving behaviors and minimizing driving workload under both task conditions.

• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.359-368
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• 2006

AAA(Authentication, Authorization, Accounting) is the service that offers authentication, authorization, and accounting method, and every terminal that accesses the network requires this AAA service. The authentication process of a mobile terminal is as follows: a mobile phone accesses an authentication server in a home network via the authentication service in an external network, which receives the authentication result. And, for the home authentication server to offer secure service, a unique key is distributed for the secure communication between the external agent and the user, the external agent and the home authentication server, and the user and the home authentication server. This paper discusses and proposes the key distribution for secure communication among external authentication servers when a mobile terminal travels to an external network. As the proposed method does not require the home authentication server to reissue another authentication when a user travels to other external networks, it reduces the overload in the home authentication server. It can also distribute a PIN-driven key.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.106-113
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• 2008

In this paper, we will design and substantiate the Network Traffic management system(MAGI), which makes up for the weak points of existing Network Monitoring tools and realize dynamic firewall; MRTG, ntop, ethereal, and nettest. The Network Traffic Monitoring and analyzing system differs from existing software-based Network Monitoring tools as MAGI is a combination of software and hardware. Not only the innovative web user interface applied to the software makes analyzing traffic simpler, but it also has a function for monitoring and managing conditions of the hardware. The web user interface implemented with PHP and MySQL helps to use the database and as a result, analyzing data becomes easier. On the hardware part, the appliance is configured as a bridge in a network. As a result, managed system does not have overload.

• Korean Journal of Childcare and Education
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• v.12 no.4
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• pp.23-40
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• 2016

The purposes of this study were 1) to examine the differences in job stress, teacher efficacy, emotion-focused coping strategies and depression of teachers in early childhood education and care according to their demographic backgrounds, 2) to investigate the influences of these variables on depression. 586 teachers in ECEC answered the questionnaires and the collected data were analyzed through frequence, percentages, Pearson's correlations, One-Way ANOVA, Bonferroni post hoc test, and stepwise regression using SPSS 21.0. The findings are as follows. First, job stress was significantly different according to ECEC teachers' ages and types of centers they were employed at teacher efficacy was significantly different according to their ages and education levels, emotion-focused coping strategies and depression were respectively significantly different according to ages, types of centers and education levels. Second, ECEC teachers' depression was influenced by undercontrolled expressionof emotion-focused coping strategies, home connection and promotion of positive learning environment of teacher efficacy, undercontrolled thinkingof emotion-focused coping strategies and work overload and job stress in order. These results imply that a support system and a policy should be established for ECEC teachers to express and understand their emotions in a positive way and related information should be provided to them through workshops.

• Korean Journal of Occupational Health Nursing
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• v.20 no.3
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• pp.250-260
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• 2011

Purpose: The purpose of this study was to describe the role experiences of occupational health nurse. The research question was "what are daily experiences in practice?" Methods: The data were collected through the focus-group interviews with nine occupational health nurses and analyzed by the grounded theory of Strauss and Corbin (1998). Results: The core category on occupational health nurse role experience was named as "struggling alone with the dual role". The causal conditions included 'unfamiliar area' and 'new work'. The contextual conditions included 'overload of work, 'tasks beyond OHN job' and 'disharmony with colleagues'. The intervening conditions were analyzed as supportive factors and discouraging factors. There were action/interaction strategies 'getting information about tasks', 'working as a professional', 'establishing a cooperative relationship', 'seeking help' by trying to regulate the phenomenon. Finally they succeed in 'establishing the identity' and 'feeling proud', but sometimes they could be 'suffering from low morale', or 'considering turnover'. Conclusion: Through these results, it can be explained that occupational health nurses have been exerting themselves to establish their role with various situation through the conflicted context. Based on the findings, we suggest developing the diverse continuing education programs to be tailored for OHN's needs and reinforcing the occupational health services under the legal and political support.

• Journal of Information Technology and Architecture
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• v.9 no.4
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• pp.455-464
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• 2012

Due to the recent data explosion, methods which can meet the requirement of large data analysis has been studying. This paper proposes MRIterativeBUC algorithm which enables efficient computation of large data cube by distributed parallel processing with MapReduce framework. MRIterativeBUC algorithm is developed for efficient iterative operation of the BUC method with MapReduce, and overcomes the limitations about the storage size and processing ability caused by large data cube computation. It employs the idea from the iceberg cube which computes only the interesting aspect of analysts and the distributed parallel process of cube computation by partitioning and sorting. Thus, it reduces data emission so that it can reduce network overload, processing amount on each node, and eventually the cube computation cost. The bottom-up cube computation and iterative algorithm using MapReduce, proposed in this paper, can be expanded in various way, and will make full use of many applications.