• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.315-327
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• 2017

Security threats such as unauthorized access and data tampering can occur during the virtual machine migration process. In particular, since virtual machine migration requires users to transfer important data and infrastructure information, it is relatively risky to other cloud services in case of security threats. For this reason, there is a need for dynamic authentication for virtual machine migration. Therefore, this paper proposes an OTP-based dynamic authentication framework to improve the vulnerabilities of the existing authentication mechanism for virtual machine migration. It consists of a virtual machine migration request module and an operation module. The request module includes an OTP-based user authentication process and a migration request process to a data center when a user requests a migration. The operation module includes a secure key exchange process between the data centers using SPEKE and a TOTP-based mutual authentication process between the data center and the physical server.

• KIISE Transactions on Computing Practices
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• v.22 no.1
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• pp.26-31
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• 2016

Migrim(Migration enhanced Grid Middleware) is a communication middleware between embedded devices and multiple servers. In traditional client-server communication, users' requests are sent to and processed by a designated server even though the server may suffer from a heavy load. In addition, the designated server may not have proper information to process the user's request correctly. Proposed connection migration mechanism and transaction migration mechanism are designed to improve the performance and accuracy of request processing. The connection migration is a procedure for delegating a connection to another server, which results in a well-distributed balancing of load among the servers. The transaction migration is a procedure for delegating a transaction to another server, and improves the accuracy of response.

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.226-229
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• 2002

본 논문에서는 멀티미디어 어플리케이션의 핵심인 오디오나 비디오와 같은 연속 미디어에서 hiccup의 발생을 최소화시키기 위한 기존의 연속 디스플레이, replication, request migration을 소개하고, 슬롯 예약 알고리즘과 완전 연결 버퍼링 알고리즘을 제안하였다. 제안한 두 알고리즘은 기존의 partial replication과 request migration에서 일어나는 hiccup 발생과, startup latency를 슬롯 예약과 디스크와 버퍼간의 완전 연결을 이용하여 최소화하였다. 향후 제안된 알고리즘은 구체적인 통계적 모델을 제시하여 다양한 재생 요구 빈도수에 따른 검증이 필요하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4207-4222
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• 2016

In a P2P (Peer-to-Peer) VoD (video-on-Demand) streaming system, the nodes' load is an important factor which affects the system performance. In the system, some nodes may receive too many requests, which leads to overload. On the other hand, some other nodes may receive too few requests, which leads to low utilization. Therefore, designing a reasonable load balancing strategy is important. However, existing related studies cannot handle this problem effectively, because they don't have an efficient dynamic load information management mechanism, and they don't distinguish the difference of requests when transfer the nodes' load. In this paper, to manage the dynamic load information efficiently, we design a load management table for each node. Based on the load information, we propose a load balancing strategy which uses a request migration algorithm (LBRM). Through simulations, our scheme can handle the load imbalance problem effectively and improve the users' playback fluency.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.11-21
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• 2015

If the cloud computing environment is not sufficiently provide the required resources due to the number of virtual server to process the request, may cause a problem that the load applied to the specific server. Migration administrator receive the resources of each physical server for improving the efficiency of the virtual server that exists in the physical servers, and determines the migration destination based on the simulation results. But, there is more overhead predicting the future resource consumption of all the physical server to decide the migration destination through the simulation process in large and complex cloud computing environments. To solve this problem, we propose an improved prediction method with the simulation-based approach. The proposed method is a fuzzy-logic based priority model for VM migration. We design a proposed model with the DEVS formalism. And we also measure and compare a performance and migration count with existing simulation-based migration method. FPLM shows high utilization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.131-134
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• 2005

This paper describes the efficient peer-to-peer migration method of Grid service agent on the mobile agent based P-Grid. The migration mechanism for transmitting service agent upon the service request is based on the peer's logic network topology. The network topologies that this system uses are organized as star topology, ring topology and tree topology, and agents are migrated by the master/slave method and serial/parallel method. The migration method of services is chosen based on the execution range and characteristic of the requested service. Also, the entire execution time of service is affected by the performance of peer that is a part of network topology, and the migration order, Therefore, the system monitors the performance of peers, and determines the migration priority based on analyzing and learning history. The system can reduce service execution time efficiently with decisions of migration method for service agent and priority of peers.

• Journal of Internet Computing and Services
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• v.18 no.4
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• pp.51-59
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• 2017

With the growth of Cloud computing, it is important to consider resource management techniques to minimize the overall costs of management. In cloud environments, each host's utilization and virtual machine's request based on user preferences are dynamic in nature. To solve this problem, efficient allocation method of virtual machines to hosts where the classification of virtual machines and hosts is undetermined should be studied. In reducing the number of active hosts to reduce energy consumption, thresholds can be implemented to migrate VMs to other hosts. By using Fuzzy logic in classifying resource requests of virtual machines and resource utilization of hosts, we proposed an adaptive VM allocation and migration approach. The allocation strategy classifies the VMs according to their resource request, then assigns it to the host with the lowest resource utilization. In migrating VMs from overutilized hosts, the resource utilization of each host was used to create an upper threshold. In selecting candidate VMs for migration, virtual machines that contributed to the high resource utilization in the host were chosen to be migrated. We evaluated our work through simulations and results show that our approach was significantly better compared to other VM allocation and Migration strategies.

• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.953-961
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• 2000

In this paper, we propose the algorithm which solve synchronization problem happened migrating service objects. Load imbalance is occurred due to allocate different amount of load to be proposed to each node in distribute system. To solve this problem, the service objects have to be migrated from heavily loaded node to lightly loaded node. And in such a process, the synchronization problem may occur when client request a service object migrated incompletely. Therefore, we describe the environment of executing service objects, the importer/exporter/trader model compatible with migration of service objects, and appropriate migration algorithm, Finally, we analyze the conditions of problems, and propose the solution of each situations. Also, the performance advantages of using proposed algorithms are quantified through a simulation study.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.445-447
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• 2002

본 논문에서는 연속 미디어에 있어서의 hiccup-free 디스플레이, startup latency와 많은 관련이 있는 데이터 배치 방법 및 startup latency를 줄이기 위한 복제 기술(완전복제, 선택복제, 부분복제)을 검토하고 그중 부분복제 기술에 있어서 그룹에 비어있는 슬롯이 없는 경우 request migration이 불가능하여 hiccup이 발생할 수 있는 경우에 그룹의 슬롯을 예약함으로써 hiccup을 줄인 수 있는 알고리즘을 제안하였다. 이 슬롯 예약 알고리즘은 시스템의 처리율은 다소 줄었지만 hiccup-free 디스플레이가 가능하도록 하였다.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.532-532
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• 2018

This article has been retracted at the request of the authors and/or the Editor in Chief. Reason: After the paper published, the authors have found that the intellectual property for this paper was a company's own. As a result, the authors have elected to withdraw the complete article with apologies to the scientific community