• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.476-487
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• 2009

The virtual memory system in 4.4 BSD operating systems exploits a clustering scheme to reduce disk I/Os in paging out (or flushing) modified pages that are intended to be replaced in order to make free rooms in memory. Upon the page out of a victim page, the scheme stores a cluster (or group) of modified pages contiguous with the victim in the virtual address space to swap disk at a single disk write. However, it fails to find large clusters of contiguous pages if applications change pages not adjacent with each other in the virtual address space. To address the problem, we propose a new clustering scheme called Multiple-Object Clustering (MOC), which together stores multiple clusters in the virtual address space at a single disk write instead of paging out the clusters to swap space at separate disk I/Os. This multiple-cluster transfer allows the virtual memory system to significantly decrease disk writes, thus improving the page-out performance. Our experiments in the FreeBSD 6.2 show that MOC improves the execution times of realistic benchmarks such as NS2, Scimark2 SOR, and nbench LU over the traditional clustering scheme ranging from 9 to 45%.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.315-316
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• 2016

This paper proposes an enhanced distributed generation (DG) unit with an adaptive virtual impedance control approachin order to address the inaccurate reactive power sharing problems. The proposed method can adaptively regulate the DG unit thanks to the equivalent impedance, andthe effect of the mismatch in feeder impedance is compensatedto share the reactive power accurately.The proposed control strategy can be implemented directly without any requirement of pre-knowledge of the feeder impedances. Simulations are performed to validate the effectiveness of the proposed control approach.

• International Journal of Computer Science & Network Security
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• v.21 no.5
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• pp.52-56
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• 2021

There is no assurance that malware could only cause virtual damage to computer programs and data as its potential is endless. However, legal provisions were earlier developed to cater to either a physical damage caused by a physical action or a virtual damage caused by a virtual action. When crossovers occur, it becomes quite uncertain as to how viable the current laws are in handling this matter. The author seeks to address the issue from the perspective of the laws of Malaysia.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.373-375
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• 2009

This paper introduces the concept of Tangible Shopping conducting in virtual world. The main idea of this paper is to combine the concept of web 2.0 mashup into shopping activities in virtual world. Feature of annotation and web browsing are also included in this concept. This research aims to enhance web shopping activities from the conventional approach into new way which deliver tangible shopping experiences to users. At the beginning, we review the state-of-the-art of virtual worlds and Web 2.0 Mashup. Next, we review our related work. Then, we address the design and implementation of tangible shopping in virtual worlds.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1131-1138
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• 2015

As the size of the internet market grows rapidly, the number of IPv4 addresses available is being exhausted, while transition to IPv6 is being delayed. As the best alternative solution, Network Address Translation(NAT) scheme is being used. It connects the public internet network with the private internet network in order to reduce the waste of IPv4 addresses space. The purpose of this paper is to study the effective example of network based on common virtual network using Packet Tracer with topology designed rather than usual theoretical approach in Dynamic NAT and PAT, which allows more efficient use of address space.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.68-71
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• 2012

본 논문은 운영 체제(Operating System)에서 수행되는 프로세스(Process)의 가상 주소 공간(Virtual Address Space)을 기존의 단일 가상 주소 공간에서 다중 가상 주소 공간으로 확장시켜서, 하나의 프로세스가 기존보다 더욱 넓은 가상 메모리 영역을 쉽게 사용할 수 있도록 해주는 방안을 제안한다. 최근 컴퓨팅 기기들은 비약적으로 증가한 메모리를 쉽게 사용할 수 있는 수단이 필요하다. 최근 PAE(Physical Address Extension)를 지원하는 32 비트 프로세서나 32 비트 명령어를 같이 지원하는 64비트 프로세서들은 프로세스의 가상 주소 크기보다 더욱 큰 용량의 메모리를 사용할 수 있어서, 한 프로세스가 장착된 메모리의 일부분 밖에 사용할 수 없는 일이 발생한다. 이를 해결하기 위해서 64비트 프로세서의 경우 64-비트 명령어를 사용하지만 이는 프로그램의 명령어 크기나 포인터 변수 크기의 증가로 메모리 사용량을 크게 늘릴 수 있어서 서버 컴퓨터나 데스크탑 PC 와 같이 충분한 양의 메모리를 장착한 시스템에서만 효과적이다. 본 논문에서 제안하는 다중 주소 공간을 지원하는 프로세스는 모바일 및 임베디드 기기와 같이 상대적으로 제한된 용량의 메모리를 지원하는 시스템에 유용할 것으로 기대한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.11
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• pp.1267-1276
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• 2014

As the volume of internet rapidly increases, the number of IPv4 addresses available is quickly declining, while transition to IPv6 is being delayed. As a interim solution, Variable-Length Subnet Masking(VLSM) addressing scheme, which varies the length of each IP address allowing more efficient, is being used. This paper suggests effective example of network based on virtual network with topology designed using VLSM charting rather than usual theoretical approach in VLSM, which allows more efficient use of address space.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.76-91
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• 1996

In this paper, we proposed the new medium access control protocol for the virtual token bus netowrk. The network is applied to inter-processor communication network of large capacity digital switching system and digital mobile system with distributed control architecture. in the virtual token bus netowrk, the existing medium access control protocols hav ea switchove rtime overhead when traffic load is light or asymmetric according ot arbitration address of node that has message to send. The proposed protocol optimized average message delay using cyclic bus access chain to exclude switchover time of node that do not have message to send. Therefore it enhanced bus tuilization and average message delay that degrades the performance of real time communication netowrks. It showed that the proposed protocol is more enhacned than virtual token medium access control protocol and virtual token medium access control protocol iwth reservation through performance analysis.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1603-1609
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• 1998

In this paper, we present a development of IP addresstranslator for virtual group network service and an application to Korea Information Infrastructure Pilot projects in Daeduk Science town network, This method can be a way to provide network service for limited virtual groups which are connected to a specialized network. Also this can be used to provide a new network environment for closed user groups in Intranet applications.

• Journal of Communications and Networks
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• v.14 no.3
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• pp.319-335
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• 2012

In this study, we design an applicable model enabling internet protocol television (IPTV) service providers to use a virtual network (VN) for IPTV service delivery. The model addresses the guaranteed service delivery, cost effectiveness, flexible control, and scalable network infrastructure limitations of backbone or IP overlay-based content networks. There are two major challenges involved in this research: i) The design of an efficient, cost effective, and reliable virtual network topology (VNT) for IPTV service delivery and the handling of a VN allocation failure by infrastructure providers (InPs) and ii) the proper approach to reduce the cost of VNT recontruction and reallocation caused by VNT allocation failure. Therefore, in this study, we design a more reliable virtual network topology for solving a single virtual node, virtual link, or video server failure. We develop a novel optimization objective and an efficient VN construction algorithm for building the proposed topology. In addition, we address the VN allocation failure problem by proposing VNT decomposition and reconstruction algorithms. Various simulations are conducted to verify the effectiveness of the proposed VNT, as well as that of the associated construction, decomposition, and reconstruction algorithms in terms of reliability and efficiency. The simulation results are compared with the findings of existing works, and an improvement in performance is observed.