• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1825-1842
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• 2013

Rapid growth of the IT industry has led to significant energy consumption in the last decade. Data centers swallow an enormous amount of electrical energy and have high operating costs and carbon dioxide excretions. In response to this, the dynamic consolidation of virtual machines (VMs) allows for efficient resource management and reduces power consumption through the live migration of VMs in the hosts. Moreover, each client typically has a service level agreement (SLA), this leads to stipulations in dealing with energy-performance trade-offs, as aggressive consolidation may lead to performance degradation beyond the negotiation. In this paper we propose a heuristic based resource allocation of VM selection and a VM allocation approach that aims to minimize the total energy consumption and operating costs while meeting the client-level SLA. Our experiment results demonstrate significant enhancements in cloud providers' profit and energy savings while improving the SLA at a certain level.

• Journal of Information Technology Services
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• v.11 no.4
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• pp.215-231
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• 2012

It is well known that SaaS(Software as a Service) changeover gives several advantages to organization. One of the advantages is the cost reduction effect of IT resources as well as IT human resources. Another one is the curtailment of software development workload in the field of informatization promotions. Nonetheless, it is hard to find comparison cases regarding the quantitative measurement of the introduction of SaaS before and after. Accordingly, when the Government IDC tries to adopt SaaS, it absolutely needs the empirical study whether SaaS is cost-effectiveness or not. In this study, we focus on variation in the Government administration common tasks, processes and labor costs. Using the Man-Month(MM) estimation methods, We verify that how much TCO(Total Cost of Ownership) is reduced per year.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.171-174
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• 2013

Virtualization technology opened a new era in the field of Data intensive, Grid and Cloud Computing. Today's Data centers are smarter than ever leveraging the Virtualization technology. In response to that, Dynamic consolidations of Virtual Machines (VMs) allow efficient resource management by live migration of VMs in the hosts. Moreover, each client typically has a service level agreement (SLA), leads to stipulation in dealing with energy-performance trade-off as aggressive consolidation may lead to performance degradation beyond the negotiation. In this paper we propose a Cloud Based CDN approach for allocation of VM that aims to maximize the client-level SLA. Our experiment result demonstrates significant enhancement of SLA at certain level.

• The Journal of the Korea Contents Association
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• v.6 no.11
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• pp.295-301
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• 2006

The scope ID field of IPv6 multicast address indicates the zone of the destination for which a multicast traffic is intended. Without any further examination on the header field, the scope ID enables a router to determine whether the traffic will be forwarded to a subnet or not. For the graceful migration from IPv4 networks to IPv6 networks, various IPv6 applications working through IPv4 networks are indispensable during the migration period. This paper describes development of an interactive remote lecture system providing service integration on voice, image, and data of teaching materials. Access right to the network for dialog among multicast group members is controlled via additional TCP (Transmission Control Protocol) session. A jitter buffer algorithm was implemented to improve the voice communication jitters.

• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.11-21
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• 2013

Recently operating a large scale computing resource like a data center becomes easier because of the virtualization technology that virtualize servers and enable flexible resource provision. The most of public cloud services provides automatic scaling in the form of scale-in or scale-out and these scaling approaches works well to satisfy the service level agreement (SLA) of users. However, a novel scaling approach is required to operate private clouds that has smaller amount of computing resources than vast resources of public clouds. In this paper, we propose a hybrid server scaling architecture and related algorithms using both scale-in and scale-out to achieve higher resource utilization rate for private clouds. We uses dynamic resource allocation and live migration to run our proposed algorithm. Our propose system aims to provide a fine-grain resource scaling by steps. Thus private cloud systems are able to keep stable service and to reduce server management cost by optimizing server utilization. The experiment results show that our proposed approach performs better in resource utilization than the scale-out approach based on the number of users.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.8
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• pp.375-387
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• 2005

This paper presents an application of parallel Genetic Algorithm-Tabu Search (GA-TS) algorithm to search an optimal solution of a service restoration in distribution systems. The main objective of service restoration of distribution systems is, when a fault or overload occurs, to restore as much load as possible by transferring the do-energized load in the out of service area via network reconfiguration to the appropriate adjacent feeders at minimum operational cost without violating operating constraints, which is a combinatorial optimization problem. This problem has many constraints with many local minima to solve the optimal switch position. This paper develops parallel GA-TS algorithm for service restoration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solutions of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper $10\%$ of the population to enhance the local searching capabilities. With migration operation, best string of each node is transferred to the neighboring node after predetermined iterations are executed. For parallel computing, we developed a PC cluster system consists of 8 PCs. Each PC employs the 2 GHz Pentium IV CPU and is connected with others through ethernet switch based fast ethernet. To show the validity of the proposed method, proposed algorithm has been tested with a practical distribution system in Korea. From the simulation results, we can find that the proposed algorithm is efficient for the distribution system service restoration in terms of the solution quality, speedup, efficiency and computation time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.314-324
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• 2004

Recently, high-speed internet subscribers have grown continuously, and reached up to 10 millions. But existing network management that is responsible only for user access is confronted with many difficulties, since user access network(xDSL, Cable, B-WILL, and so on) has diversified and value added wired/wireless contents service has developed. In this paper propose the Agent based Inter Networking platform as object-oriented hierarchical system that can provide various service such as access QoS(Quality of Service), customized application service and security service according to user on demand. This system has divided into two parts(user agent and agent management system ＆ local and central management systems). Management system periodically receive status information such as bandwidth, download speed, delay, current service, and so on, and process them, then build a policy based on processed information. According to personal user profile that is generated by this policy, the customized service can be provided for users. And This system adopt the object-oriented modeling in case that system migration and integration, and implement a system that is robust and stable for security through hierarchical server system.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.19-22
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• 2010

Migratory birds, by crossing significant ecological barriers, carry and may subsequently introduce exotic seeds into new ecological zones during period of migration. The study of epizoochory, which includes seed dispersal by adhesion to bird feathers, has been relatively neglected compared to the study of seed dispersal by frugivores. To determine whether exotic seeds are being imported to stopover islands by migrating birds, and to estimate the quantity of seeds of exotic species being introduced, we examined migratory birds that were captured in mist nets for attached exotic plant diaspores in 2008 and 2009 on Hongdo Island, Korea. From a total of 3,947 birds examined, we found exotic seeds of Japanese Chaff Flowers (Achyranthes japonica) attached to three species of migratory birds (0.08%; Eurasian Bittern Botaurus stellaris, Swinhoe's Rail Coturnicops exquisitus and Oriental Turtle Dove Streptopelia orientalis). Despite the low occurrence of A. japonica seeds on the external parts of birds, the results suggest that migratory birds may be potential dispersing agents for A. japonica, a species that is currently threatening native ecosystems on many islands in Korea.

• Journal of Korean Society of Rural Planning
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• v.14 no.3
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• pp.27-36
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• 2008

Rapid increase of aging population and progressed migration from rural areas to urban areas have caused deficit of bus routes in local cities. This increasing burden of operation deficit affects the movement strategy of the transportation vulnerable who are using buses. Along with dramatically increased aging in Korea, there is an urgent need to implement a new method which can guarantee mobility rights of public transportation especially for the elderly. This study focuses on the case of Demand Responsive Transit(DRT) system that has been operating in America, Europe, Japan, etc. Kimhae(Sangdong-myeon and Saengnim-myeon) is selected as a study area. This study investigated the possibility of adopting DRT system on the perspectives of the consumer and provider by the analysis of traffic condition such as the number of transportation vehicles, present bus service and regulation and conduct of questionnaire survey which includes present bus service and DRT system and so on. In conclusion, DRT system in Kimhae city will reduce transport cost, increase affordability through the betterment of service level and secure mobility rights for the transportation vulnerable.

• Journal of the Korea Society of Computer and Information
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• v.3 no.4
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• pp.19-26
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• 1998

Mobile database system address information processing based on database system in mobile computing environment. In the mobile database system, when a mobile transaction host enter a other radio coverage area called a cell while processing a transaction, it have to alter the communication network address to new database server. This is called transactional service handoff. This paper propose a transaction processing scheme for providing the proper function of this transactional service handoffs in mobile database system. This scheme apply coordinator migration mechanism which perform the transaction in new database server when posed to be the transaction service handoff. Fially, the proposed scheme will improve system performance by minimizing the tansmission of message for processing the transactions in mobile database system.