• Journal of The Korean Association of Information Education
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• v.22 no.1
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• pp.33-40
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• 2018

This study highlights the experiences and lessons learned, through the introduction and production of virtual reality in elementary school classes. We analysed the effects of virtual reality-contents production education using the data from the K.A.P survey, as well as the results from the class using virtual reality. We used Cospaces as a tool for coding the virtual reality content. It was not difficult for students to learn its functions because it could be coded with blockly based programmes. We analysed the results in the practice area. Based on these results, we suggest how to apply this to the elementary school field.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.8
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• pp.491-498
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• 2014

Due to the ossification of current Internet, it is hard to accommodate new service requirements. One of the solutions to this problem is network virtualization. In this paper, we propose a heuristic virtual network embedding method for network virtualization. The proposed method checks whether the candidate substrate nodes in the substrate network have the possibility of satisfying virtual link requirements. It gives priority to the virtual nodes and the substrate nodes, and embeds the node with higher priority first. Also, the proposed method tries to cluster the mapped substrate nodes if possible. We evaluate the performance of the proposed method in terms of time complexity and virtual network acceptance rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1146-1154
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• 2010

A virtual machine lease service in the cloud computing environment has been implemented using the open source cloud computing platform, OpenNebula. In addition, a web-based cloud user interface is developed for both convenient resource management and efficient service access. The present virtual machine allocation scheme adopted in OpenNebula has performance reduction problem because of not considering CPU allocation scheduler of the virtualization software. In order to address this problem we have considered both the priority of the idle CPU resources of the cluster and credit scheduler of Xen, which resulted in performance improvement of the OpenNebula virtual machine scheduler. The experimental results showed that the proposed allocation scheme provided more virtual machine creations and more CPU resource allocations for cloud service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3B
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• pp.171-182
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• 2003

In this paper, we propose an efficient and simple fair queueing algorithm, called Minimum Possible Virtual Start Time Fair Queueing (MPSFQ), which has O(1) complexity for the virtual time computation while it has good delay and fairness properties. The key idea of MPSFQ is that it has an easy system virtual time recalibration method while it follows a rate-proportional property. MPSFQ algorithm recalibrates system virtual time to the minimum possible virtual start time of all backlogged sessions. We will show our algorithm has good delay and fairness properties by analysis.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.19-23
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• 2008

The development of computer graphics techniques came after development of various entertainment industry such as movies, game and so on, and techniques that make diverse objects in virtual space and control the action of objects are growing rapidly. Especially objects(characters) play an important role in encouraging virtual space at computer animation field. If lots of objects are animated in virtual space, undesired matters of fixed topography or collision between objects etc occur. In order to solve this problem, we need control techniques in detail. This paper presents and implements collision evasion with submarine topography in a virtual aquarium and control technique about collision evasion with other objects.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.1 s.28
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• pp.55-62
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• 2004

More recently, multiple reference based RTK GPS techniques(VRS ; Virtual Reference System) are becoming increasingly important for many precise GPS applications in many countries to overcome the constrained distance limitations of standard RTK systems. The precision of the position solutions of the rover receiver is closely connected with that of the corresponding virtual reference points(VRPs). The objective of this paper is to investigate the accuracy and performance of the VRPs on the test network have been made in post mode, and the overall analysis results were presented by comparing the solutions for the VRPs from the existing GPS reference station with the true values of the coordinates used to produce the observation data. The results show the reasonable accuracies of VRPs in the network area by using the VRS concept in post mode.

• The KIPS Transactions:PartB
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• v.12B no.2 s.98
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• pp.143-150
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• 2005

The Field is a simulated virtual environment specifically designed to assist elementary students learn the basic scientific inquiry skills such as observation, data collection, and generating and verifying hypothesis. Over the last four years, the Field has been used to teach inquiry learning in the context of mathematics and science in an elementary school. During the studies, it was observed that students suffered from problems in navigation, wayfinding, and data collection. First, this papers discusses the problems and the technical aids we have iteratively developed to address these issues. We will then discuss the impact of the technical aids on the student's behaviors.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.333-338
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• 2007

시스템 가상머신 환경은 높은 하드웨어 효율성과 높은 보안을 요구하는 시스템에서 그 사용이 점차 늘어나고 있다. 최근 많이 알려진 하이퍼바이저 가상머신 시스템은 높은 아이솔레이션과 보안성을 보장하나 각 게스트 운영체제 별로 운영체제 이미지를 가지기 때문에 하드웨어 효율성이 떨어지는 반면, 컨테이너 기반 가상머신 시스템은 운영체제 이미지의 공유로 인하여 높은 자원 효율성과 확장성을 가진다. 그러나 메모리 자원의 아이솔레이션에 대하여 취약점을 갖는 문제점을 안고 있다. 본 논문에서는 컨테이너 기반 가상머신 시스템에서 동적으로 각 가상머신별로 메모리 사용량 증가에 따른 페이지 히트율-곡선(Hit-Ratio-Curve)을 측정하였다. 이 곡선을 관찰해 보면 각 가상머신의 메모리 필요량을 알 수 있으며 이를 기반으로 메모리 자원을 할당하게 될 경우 효과적으로 메모리 자원의 아이솔레이션을 제공할 수 있게 된다. 본 논문에서는 대표적인 컨테이너 기반 가상머신인 리눅스 VServer가 적용되어 있는 리눅스 2.6.17 커널에 직접 구현하였으며, Lmbench 및 리눅스 커널 컴파일 등을 통하여 오버헤드를 측정하였고 $1.6{\sim}7.2%$의 적은 오버헤드로 이를 측정할 수 있음을 확인하였다.

• Annual Conference of KIPS
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• 2018.10a
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• pp.497-500
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• 2018

데이터 센터를 기반으로 서비스를 수행하는 기업들은 비용절감을 위해 서버 가상화 기술을 이용한다. 서버 가상화를 이용하는 기업들은 대부분 하이퍼바이저 기반의 서버 가상화 기술을 사용하며, 이 경우 하드웨어 가상화를 통해 커널 단에서 많은 I/O와 리소스를 처리해야 한다. 따라서 하이퍼바이저 기반의 서비스는 느리다는 단점이 있으며 이를 해결하기 위해 컨테이너 기반의 가상화 기술을 이용할 수 있다. 하지만 컨테이너 기반의 네트워크 또한 문제점이 존재한다. 컨테이너 기반의 네트워크는 유연한 네트워크를 구성하기 어렵고, 기존의 컨테이너 네트워크 인터페이스를 활용할 경우 데이터 전송 성능이 저하된다. 본 논문에서는 컨테이너 오케스트레이션 툴인 Kubernetes와 SDN (Software-Defined Network) 기반의 가상전용 네트워크 연계 환경을 구축하고 이에 적합한 컨테이너 네트워크를 연구하여 이의 문제점을 해결한다. 즉, 가상전용 네트워크와 Kubernetes의 연계를 통해 고성능의 유연한 네트워크를 구성할 수 있는 프레임워크를 개발하여 기존 컨테이너 기반 네트워크와 비교하고 성능을 검증했다.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.405-412
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• 2002

The embedded system has less fast CPU and lower memory than PC(personal Computer) or Workstation system. Therefore embedded operating is system is designed to efficiently use the limited resource in the system. Virtual memory management or the embedded linux have a low efficiency when page fault is occurred to get a data from I/O device. Because a data is moving from the swap device to main memory. This paper suggests virtual memory compression algorithm for improving in virtual memory management and capacity of space. In this paper, we present a way to performance implement a virtual memory compression system that achieves significant improvement for the embedded system.