• Informatization Policy
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• v.21 no.1
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• pp.35-56
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• 2014

Information and communication technologies(ICT) allow and force people to work anywhere, anytime using remote databases and application systems available in real-time twenty four hours a day and seven days a week. With the real time nature of ICT, individual work is becoming more and more fragmented. Instead of working on a similar task repeatedly, individuals are required to respond to e-mails and inquiries through social networks, work on planning documents, work on presentation documents, work on spreadsheets, input necessary data on company databases, generate necessary reports from the database, run teleconference, etc., all maybe in a day's work. Work fragmentation may impact negatively on productivity as the flow is interrupted, but it may increase the productivity by allowing people to handle multiple tasks in a shorter time period. This study explores the types of work fragmentation and their characteristics. An online survey was administered to collect data about work fragmentation and work characteristics including autonomy, complexity, flexibility, usage of ICT, etc. 300 cases were used in the analysis. Analysis of k-mean cluster indicated four different types of work fragmentation: concentrated, temporally distributed, spatially distributed, and fully fragmented.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.131-137
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• 2006

In swarm robot systems, each robot must behaves by itself according to the its states and environments, and if necessary, must cooperates with other robots in order to carry out a given task. Therefore it is essential that each robot has both learning and evolution ability to adapt the dynamic environments. In this paper, the new learning and evolution method based on reinforcement learning having delayed reward ability and distributed genetic algorithms is proposed for behavior learning and evolution of collective autonomous mobile robots. Reinforcement learning having delayed reward is still useful even though when there is no immediate reward. And by distributed genetic algorithm exchanging the chromosome acquired under different environments by communication each robot can improve its behavior ability. Specially, in order to improve the performance of evolution, selective crossover using the characteristic of reinforcement learning is adopted in this paper. we verify the effectiveness of the proposed method by applying it to cooperative search problem.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2092-2105
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• 1997

In this paper, we propose a load sharing scheme in distributed systems. In the proposed scheme, the state of each host is classified as a server or a source by its current load and, to prevent excessive state changes of each host, we used three threshold values for identifying the current state of each host. Based on the threshold values, some hosts, called brokers, manage the servers registered to them. The brokers, whose number is determined by the system utilization factor and the total number of hosts, support task migration processes from overloaded sources to lightly loaded servers. Also they can hand over the broker's role to another host when it is overloaded. Simulation studies were performed for examining the sensitivity of each system parameters such as threshold values, utilization factor, the number of hosts, and the number of brokers to the system performance indices including mean response time, mean queue length.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1340-1346
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• 2016

Utilization of Distributed Generations (DGs) using Renewable Energy Sources (RESs) has been constantly increasing as they provide a lot of environmental, economic merits. In spite of these merits, some problems with respect to voltage profile, protection and its coordination system due to reverse power flow could happen. In order to analyze and solve the problems, accurate modeling of DG systems should be preceded as a fundamental research task. In this paper, we present a PhotoVoltaic (PV) generation system which consists of practical PV cells with series and parallel resistor and an inverter for interconnection with a main distribution system. The inverter is based on controllable current source which is capable of controlling power factors, active and reactive powers within a certain limit related to amount of PV generation. To verify performance of the model, a distribution system based on actual data is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are also performed and it is shown from simulation results that the model presented is very effective to study DG-related researches.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.5
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• pp.591-597
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• 2007

In swarm robot systems, each robot must behaves by itself according to the its states and environments, and if necessary, must cooperates with other robots in order to carry out a given task. Therefore it is essential that each robot has both learning and evolution ability to adapt the dynamic environments. In this paper, the new polygon based Q-learning algorithm and distributed genetic algorithms are proposed for behavior learning and evolution of collective autonomous mobile robots. And by distributed genetic algorithm exchanging the chromosome acquired under different environments by communication each robot can improve its behavior ability Specially, in order to improve the performance of evolution, selective crossover using the characteristic of reinforcement learning is adopted in this paper. we verify the effectiveness of the proposed method by applying it to cooperative search problem.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.3
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• pp.60-71
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• 2017

Smart devices such as smart phones, smart TVs, and smart pads have become essential devices in recent years. As the popularity and demand grows, the performance of smart devices is also getting better and users are dealing with a lot of things such as education and business using smart devices instead of desktop. However, smart devices that still have poor performance compared to desktop, even with improved performance, have difficulty running high performance applications due to limited resources. In this paper, we propose a load balancing algorithm applying the characteristics of smart devices to overcome the resource limitations of devices. in order to verify the algorithm, we implemented the algorithm after adding the distributed processing system service in Android platform. After constructing the cluster on the smart device, various experiments were conducted. Through the analysis of the test results, it is confirmed that the proposed algorithm efficiently improves the overall distributed processing performance by effectively aggregating different amounts of computing resources in heterogeneous smart devices.

• Journal of the Korean Home Economics Association
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• v.30 no.1
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• pp.179-198
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• 1992

The purspoe of this study is to identify the socialization level of household work of the employed and unemployed housewives and it's related variables in order to provide some fundamental information for the rational and effective performation of the household task. For the purpose of this study, 700 questionnaire were distributed to the employed and unemployed wives who lived in Seoul. The data were analyed by the Frequency distribution, Percentile, t-test, F-test, Duncan's Multiple Range Test, and Multiple Regression Analysis. The main results were as follows : (1) Socialization level of household work of the employed wives was a little below medium point. When the household work was devided into three subdomains, in the domain of food and shelter, the socialization level was far below medium point. In the domain of clothes, the socialization level was a little higher than medium point. Socialization level of household work of the unemployed wives far below average. When the household work was devided into three sudbomains, in the domain of food, clothes and shelter, the socialization level was far below average, too. Socialization level of household work was significantly different according to the employment. (2) Among the background veriables, family income, household work helper, and frequency of leisure activities have a significant influence on the socialization level of the employed wives. Duration of marriage, housewife's education level and house income have a important effect on the socialization level of the unemployed wives background. (3) Among the background variabels of household work, performing competence of household work is powerful effect on the socialization level of the employed wives. And as for the unemployed wives, performing competence of household task and recognition of the velue of household work are significant variables. (4) The psychological variable such as sex-role attitude gave no noticeable influence on the socialization level of employed and unemployed wives. (5) In conclusion, classifing the variances influencing on the socialization level of household work in a measure of respcetive effect, it appears to be performing competence of household task, frequency of leisure activities, house income, sex-role attitued and educational level in the order of their influences for the employed wives. And as for the unemployed wives, it seems to be house income, educational level, performing competence of household work and frequency of leisure activities. To the two sides, the rate of explanation is shown at 35%.

• Journal of the Korean Geographical Society
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• v.36 no.5
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• pp.539-560
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• 2001

This paper aims to critically review the geographical literature on learning and proximity that stresses the role of the regions and geographical proximity in sustaining competitive advantage, and to conceptualize a relational/organizational perspective on the sources of knowledge and learning in the firm. In the first part of the paper, I argue that the geographical literature lacks the deliberate scrutiny of how learning occurs in the firm and where the sources of knowledge and learning come from. Secondly, I attempt to elaborate the concept of proximity through a relational/organizational perspective. Thirdly, I delve into how learning takes place and is realized in the firm through communities in the firm such as communities of practice, epistemic communities and task-force teams and how such communities in the firm generate knowledge and sustain loaming by drawing on relational/organizational proximity. This paper concludes by claiming that the sources of learning exist in organizational spaces, with complex geographies mobilizing distributed knowledge and competences and combining varied forms of knowledge beyond the simple demarcation of tacit and codified knowledge.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.117-124
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• 2006

In this paper, we propose the optimal migration path searching method including path adjustment and reassignment techniques for an efficient migration of mobile agent which has an autonomous ability for some task processing. In traditional agent system, if the various and large quantify of task processing were required from the users, it could be derive excessive network traffic and overload due to increasing the size of agent. And also, if an agent migrates from node to node according to routing schedules specified by the user at which the most of network traffic occurs, it could not actively cope with particular situations such as communication loss and node obstacles and required much cost for node traversal Therefore. this paper presents the migration method of agent which can try to adjust and reassign path to the destination automatically through the optimal path search using by network traffic perception in stead of the passive routing schedule by the user. An optimal migration path searching and adjustment methods ensure the migration reliability on distributed nodes and reduce the traversal task processing time of mobile agent by avoiding network traffic paths and node obstacles.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1169-1178
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• 2022

This study examines an effective operational plan of a maritime safety enforcement task that is distributed in the Ministry of Oceans and Fisheries and the Korea Coast Guard for maritime safety. Considering the sinking of the MV Sewol and Seohae vessels and the MV Hebei Spirit oil spill, normally marine safety accidents tend to not only damage human life, property, and marine environment but can also expand to disasters; therefore, precautionary measures are required. However, the Korean government takes superficial efforts in case of large-scale accidents. In case of the MV Sewol ferry, the government only focused on punishing the officials involved as a follow up and never mentioned any effective plan, such as "unification of maritime safety enforcement," in contrast to an advanced country. As a result, there are endless major and minor backward accidents. The probability of large-scale maritime accidents and backwardness accidents is increasing owing to vessels becoming large sized, high speed, and aged; sailors being unqualified; port traffic increase, development of marine leisure; and inefficiency dual marine safety systems. Therefore, based on the review of previous studies related to maritime safety, major advanced country's cases, and unified case of the vessel traffic service, this study suggests effective methods such as coastal vessel safety management, port state control and aid to navigation management, which are directly connected with maritime safety.