• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.721-730
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• 2001

Nowadays corporation networks are growing rapidly and they are needed to communicate with branch offices. Therefore, a VPN (Virtual Private Network) appears to reduce the cost of access and facilitate to manage and operate the enterprise network. Along with this trend, many studies have been done on VPN. It is important that the performance issues should be considered when VPN protocols are applied. However, most of them are limited on the tunneling methods and implementation of VPN and a few studies are performed on how installation of VPN affects the network. Therefore, in this paper, a testbed is constructed and VPN protocols are installed on it. Real traffic is generated and transmitted on the testbed to test how installing a VPN affects the network. As a result, layer 3 VPN protocol shows lower network performance than layer 2 VPN protocols. And we realize that the combination of L2TP and IPSec is the better method to install VPN than using IPSec only in the aspects of performance and security.

• Journal of KIISE:Software and Applications
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• v.30 no.11
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• pp.1044-1053
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• 2003

A virtual science experience space(VSES) using virtual reality technology including haptic device is proposed to overcome limits which the existing science education has and to improve the effect of it. Four example scientific worlds such as Micro World, Friction World, Electromechanical World and Macro World are demonstrated by the developed VSES. Van der Waals forces in Micro World and Stick-Slip friction in Friction World, the principle of induction motor and power generator in Electromechanical World and Coriolis acceleration that is brought about by relative motion on the rotating coordinate are modeled mathematically based on physical principles. Emulation methods for haptic interface are suggested. The proposed VSES consists of haptic device, HMD or Crystal Eyes and a digital computer with stereoscopic graphics and GUI. The proposed system is believed to increase the realism and immersion for user.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.46-52
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• 2008

In this paper, we present the Mont-Saint-Michel virtual reality system designed to create the virtual heritage environment, which is enriched with personalized tour guide service. The tour guide system allows users to travel in the virtual heritage site and get more information about the sites or items of user's interests. It also allows users to make their own tour guidebook with the pictures they have taken during the virtual tour and more detail descriptions from the tour guide database. It then generates the web-based tour guidebook for users to utilize it for the actual site visit or share it with others over the Internet. The components of this system are designed with the consideration of reusability to be used for other interactive tour guide systems. This paper describes the motivation the development and a preliminary user study of Mont-Saint-Michel virtual reality personalized tour guide system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1835-1844
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• 2007

Recently there have been some positive evidences on the effects of learning in a virtual environment. However, most of these educational VR systems were not deeply considered in the design of drawing a learner's attention on lesson contents, which would help enhance retained memory. Hence, a study was conducted to measure 17 subjects' attention states using EEC, ECG, GSR, and eye-tracking and their behaviors while they were given guided search task or exploration task in a virtual environment consisting of five major events. It also analyzed the subject's remembered items after their VR experiences using a surrey. This paper Int describes an overview of the ocean virtual environment used in this study, and it then explains the experimental design, apparatus, and method. It will also discuss the results by a detail analysis (in a whole VR session as well as event-related 10-second 33 sub-sessions) with the subjects' attention states and their retained memory after the learning.

• Journal of the Korea Society of Computer and Information
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• v.18 no.8
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• pp.105-111
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• 2013

This paper presents a virtual sensor system that is an effective method to test application software of smart sensors. The common way of testing sensor application is to build a test board, connect sensors to the board, and test sensor applications on the board with sensor's measurements as inputs. The problem of testing sensor application software with sensor's measurements as inputs is the restriction of test data. In other words, software testers cannot manipulate test data, because test data is generated by sensors. To solve this problem a virtual sensor system is presented in this paper. The virtual sensor system enables software testers to manipulate measurements of sensors. In the virtual sensor system, generation of virtual sensors comprises three stages - sensor selection, sensor characterization, and determination of output patterns. Sensor's measurements that can be manipulated through the virtual sensor system make the process of testing efficient. To show the usefulness of our virtual sensor system, it is applied to sensor applications in Android platform and the result of experiments is shown.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.3
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• pp.31-39
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• 2019

Virtualization technology is one of the technologies that have been attracting attention as cloud computing spreads recently. When a system is constructed using virtualization technology, mutiple operation systems can be operated in a single host operating system, thereby facilitating efficient management of computing resources. As more and more operating systems are running on the hypervisor, it is important to measure the overall performance of the virtualization system and this is becoming an important technology. In this paper, we analyze the main functions of the existing profiling tools to measure the performance of the virtualization system, and measure and classify the profiling coverage that the monitoring tools can perform for events that may occur in the virtualization system. In addition, we have studied a framework that enables performance measurement by loading appropriate profiling tools into the guest system when performance measurement is required for the virtualization system according to the information received from the remote system performing the monitoring.

• Journal of Digital Convergence
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• v.17 no.5
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• pp.235-247
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• 2019

This study was carried out to evaluate the efficacy of Virtual Reality(VR) program on recovery of functional in Stroke through systematic literature review and meta-analysis. The following databases were used to search the literature: RISS, KISS, KMbase. Keywords included 'stroke', 'CVA' 'virtual reality', 'rehabilitation', 'virtual reality program' and the evaluated articles were published from 2009 to November 2018. The statistical was used R program, the effect size of upper limb, balance and ADL were calculated by random-effects model. As a result, 9 RCT studies were meta-analyzed and were evaluated for the risk of bias by the RoB of Cochrane Collaboration; the overall risk of bias was low. The effect sizes of VR program was balance(g=.77), ADL(g=.80) as indicated by a "large effect size". Therefore, VR program is large effective in reducing balance and ADL in strokes. It is necessary to develop and apply a virtual reality-based program using more efficient program development.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.381-388
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• 2021

The purpose of this study is to analyze the effects of simulation program using virtual reality (VR). Examination of databases resulted in identification of 1,415 studies of which 3 satisfied the inclusion data. Data analysis was performed using R version 4.0.2 to calculate the effect sizes, explore possible causes of heterogeneity, and check for publication bias, using a funnel plot. The mean effect size of the simulation program was medium (g=0.35), along with the skill performance (g=0.59), satisfaction (g=0.38), knowledge (g=0.21). Finally a funnel plot was produced to check for publication bias, but no significant bias was detected. Based on these findings, the simulation program using VR affects nursing education.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.499-507
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• 2021

This study compares the educational effect using real equipment, virtual reality, and video to improve the educational and training effect of the army and verifies which method of education is excellent. The Army has made a lot of efforts to realize the actual training environment, however, it is increasingly difficult to provide the actual training environment because of 1) restrictions on securing training sites and urbanization, 2) deepening conflicts with the people, and 3) difficulties in acquiring defense budget. To resolve these issues, the use of virtual reality(VR) has the advantage to experience actual battlefield indirectly and could save budget by training in a virtual battlefield environment. In particular, in the case of dangerous or expensive weapons systems, is further required. Hence this paper studies how effective virtual reality is compared to the actual weapons system. virtual reality(VR) education is less effective than actual equipment education, but it is higher than video education. Based on this research result, it will be used as a basic data for the analysis of educational effects based in virtual reality(VR).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.807-812
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• 2021

In order to be able to interact with the user to experience it as if it were real in virtual reality contents, input/output devices that make them feel the five senses of humans are required . In virtual reality (VR), devices that stimulate sight and hearing are the most representative. For a more realistic experience, suits and gloves that stimulate the sense of touch have recently been released, but there are not many cases applied to actual contents due to the limitation of device . In this paper, we analyze a virtual reality glove that can detect hand movement and touch in a virtual world. Based on the analysis, we propose an algorithm that can sense the intensity of collision with a VR object by tactile sense by improving the UI/UX using the vibration of the feedback method used in the existing virtual reality glove. In addition, the system implemented by the algorithm is applied to an actual case.