• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.417-425
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• 2019

Storage snapshot technology allows to preserve data at a specific point in time, and recover and access data at a desired point in time. It is an essential technology for storage protection application. Existing snapshot methods have some problems in that they dependent on storage hardware vendor, file system or virtual block device. In this paper, we propose a new snapshot method for solving the problems and creating snapshots on-line. The proposed snapshot method uses a method of extracting the log records of update operations at the virtual file system layer to enable the snapshot method to operate independently on file systems, virtual block devices, and storage hardwares. In addition, the proposed snapshot mehod creates and manages snapshots for directories and files without interruption to the storage service. Finally, through experiments we measure the snapshot creation time and the performance degradation caused by the snapshot.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.1
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• pp.115-125
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• 2016

PURPOSE: The purpose of this study was to compare the effects of task-oriented training and virtual reality training on upper extremity function, balance ability, depression in stroke patients. METHODS: Forty stroke patients were randomly allocated into a task oriented training group (TTG, n = 20), a virtual reality training group (VRG, n = 20). Both groups received the usual physical therapy. In addition, TTG patients underwent task training such as sweeping the table, cup stacking, carrying wood block. VRG patients underwent virtual reality training using X-box kinect. Both groups received 30 minutes of training per day, five times per week, for twelve weeks. RESULTS: After intervention, both groups showed significant improvement on upper extremity function, balance ability, and depression. VRG showed more improvement on upper extremity function, balance ability, and depression than TTG. CONCLUSION: According to the results of this study, task-oriented training and virtual reality training are feasible and suitable for stroke patients. And virtual reality training is more effective method than task oriented training.

• Journal of The Korean Society of Integrative Medicine
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• v.5 no.3
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• pp.1-9
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• 2017

Purpose: The purpose of this study was to investigate the effects of an immersive, virtual reality-based exercise program on range of motion and dexterity in the upper extremities of stroke patients. Methods: Fifteen patients with hemiparesis after stroke participated in this study. The participants participated in Rapael Semart GloveTM, an immersive, virtual reality-based exercise program, performed for 30 minutes-, 3 times per week for 4 weeks. The Rapael Smart GloveTM program and a Box and Block Test (BBT) were used to measure range of motion and to assess dexterity, respectively, pre-and post-intervention. Results: Range of motion in pronation and supination of the forearm and flexion, extension, and ulnar deviation of the wrist improved after the intervention. Dexterity measured by BBT also improved. However, range of motion in flexion and extension of the fingers and radial deviation of the wrist did not improve. Conclusion: This study presents the effects of an immersive, virtual reality-based exercise program on hand function. In the future, a study comparing an immersive, virtual reality- based exercise program to other upper-extremity interventions for stroke patients should be conducted. A study about the effects of an immersive virtual reality program on activities of daily living is also needed.

• Journal of Information Science Theory and Practice
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• v.9 no.4
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• pp.63-74
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• 2021

Virtual Reality (VR) is one of the core components of the fourth industrial revolution as a technology that makes the virtual world feel as if it is real. VR is being used in various fields such as entertainment, advertisement, education, medical care, training, sports, and tourism, as well as providing contents for such things as games and videos. Libraries are already looking for ways to utilize VR from various angles, such as operating experiential programs. The purpose of this thesis is to develop and propose a VR-based library user education program. In order to achieve the purpose of the study, we analyzed previous studies from a theoretical perspective to find a way to construct a user education program, and also to derive possible implications based on examples of countries such as the United States and Korea that are already introducing and applying VR technology to library services. Therefore, the user education program proposed in this study can be used as a basic building block when many libraries want to develop VR-based programs in the future.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.9-17
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• 2023

Research on virtual assets has been mainly interested in policy preparation or legislation for the introduction of virtual assets, or virtual asset operation technology, but this study presents investment factors that most asset investors consider important when making investment decisions. By doing so, we came up with research results that are practically helpful to virtual asset investors. According to the research results, (1) virtual asset investors consider business models such as marketability and competitive advantage of virtual assets as the most important factors, and (2) are highly interested in factors that can be objectively judged when investing in virtual assets. The results of this study suggest that a virtual asset trading market environment that can provide objective investment information and discover various judgment factors that enable virtual asset investors to objectively judge virtual assets should be prepared, and that virtual asset businesses using core technologies will continue to grow. This suggests that a variety of policy support is needed to enable this.

• Asia pacific journal of information systems
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• v.30 no.1
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• pp.21-30
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• 2020

Bitcoin (BTC) is a type of cryptocurrency that supports transaction/payment of virtual money between BTC users without the presence of a central authority or any third party like bank. It uses some cryptographic techniques namely public- and private-keys, digital signature and cryptographic-hash functions, and they are used for making secure transactions and maintaining distributed public ledger called blockchain. In BTC system, each transaction signed by sender is broadcasted over the P2P (Peer-to-Peer) Bitcoin network and a set of such transactions collected over a period is hashed together with the previous block/other values to form a block known as candidate block, where the first block known as genesis-block was created independently. Before a candidate block to be the part of existing blockchain (chaining of blocks), a computation-intensive hard problem needs to be solved. A number of miners try to solve it and a winner earns some BTCs as inspiration. The miners have high computing and hardware resources, and they play key roles in BTC for blockchain formation. This paper mainly analyses the underlying cryptographic techniques, identifies some weaknesses and proposes their enhancements. For these, two modifications of BTC are suggested ― (i) All BTC users must use digital certificates for their authentication and (ii) Winning miner must give signature on the compressed data of a block for authentication of public blocks/blockchain.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.11
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• pp.877-882
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• 2016

Disaster robots have accepted tele-operation in order to share the intelligence of human operators and robot systems. Virtual wall is one of the tele-operation technology to support recognition of human operator. If the virtual wall can block the robot from dangers, the operator will feel comfortable and can concentrate on fundamental missions. In this paper, we proposes and compares three methods for virtual wall visualization in tele-operation using 3D reconstruction. First is a virtual wall visualized only with edges. A wall filled with transparent color is the second method. Finally, third method is a texture-mapped virtual wall. In the experiments, we discuss their merits and demerits in view of robot tele-operation.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.87-93
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• 2003

The purpose of this research is to develop a virtual reality system which enables to actually experience the virtual reality through the visual sense of human. TSS was applied in tracing the movement of moving picture in this research. By applying TSS, it was possible to calculate multiple motion vectors from moving picture, and then camera's motion parameters were obtained by utilizing the relationship between the motion vectors. For the purpose of experiencing the virtual reality by synchronizing the camera's accelerated velocity and the simulator's movements, the relationship between the value of camera's accelerated velocity and the simulator's movements was analyzed and its result was applied to the neutral network training. It has been proved that the proposed virtual reality immersion system in this dissertation can dynamically control the movements of moving picture and can also operate the simulator quite similarly to the real movements of moving picture.

• The KIPS Transactions:PartA
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• v.14A no.3 s.107
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• pp.167-172
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• 2007

VM(Virtual Machine) can be considered as a software processor which interprets the machine code. Also, it is considered as a conceptional computer that consists of logical system configuration. But, the execution speed of VM system is much slower than that of a real processor system. So, it is very important to optimize the code for virtual machine to enhance the execution time. Especially the optimizer for a virtual machine code on embedded devices requires the highly efficient performance to the ordinary optimizer in the respect to the optimized ratio about cost. Fundamentally, functions and basic blocks which influence the execution time of virtual machine is found, and then an optimization for them nay get the high efficiency. In this paper, we designed and implemented the optimizer for the virtual(or abstract) machine code(VMC) using profiling. Firstly, we defined the profiling information which is necessary to the optimization of VMC. The information can be obtained from dynamically executing the machine code. And we implemented VMC optimizer using the profiling information. In our implementation, the VMC is SIL(Standard Intermediate Language) that is an intermediate code of EVM(Embedded Virtual Machine). Also, we tried a benchmark test for the VMC optimizer and obtained reasonable results.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.434-442
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• 2018

Recently, the threat to the security and damage of important data leaked by devices of intranet infected by malicious code through the Internet have been increasing. Therefore, the partitioned intranet model that blocks access to the server for business use by implementing authentication of devices connected to the intranet is required. For this, logical net partition with the VDI(Virtual Desktop Infrastructure) method is no information exchange between physical devices connected to the intranet and the virtual device so that it could prevent data leakage and improve security but it is vulnerable to the attack to expose internal data, which has access to the server for business connecting a nonregistered device into the intranet. In order to protect the server for business, we suggest a blockchain based network partition model applying blockchain technology to VDI. It contributes to decrease in threat to expose internal data by improving not only capability to verify forgery of devices, which is the vulnerability of the VDI based logical net partition, but also the integrity of the devices.