• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.363-368
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• 2016

A storage-based VDI (Virtual Desktop Infrastructure) system has the disadvantage of degraded performance when IOs for the VDI system are concentrated on the storage. The performance of the VDI system decreases rapidly especially, in case of the boot storm wherein all virtual desktops boot simultaneously. In this paper, we propose a main memory-based virtual desktop system managing virtual desktop images on main memory to solve the performance degradation problem including the boot storm. Performance of the main memory-based VDI system is improved by storing the virtual desktop image on the main memory. Also, the virtual desktop images with large size can be stored in the main memory using deduplication technology. Implementation of the proposed VDI system indicated that it has 4 times performance benefit than the storage-based VDI system in case of the boot storm.

• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.1
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• pp.11-22
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• 2000

The paper describes creation methods of background scenes to implement realistic virtual environments in the VRSS (Virtual Reality Ship Simulator). VRSS is next-generation system constructed with virtual tools in a virtual space. Thus, it could have many benefits compared to conventional ship simulators composed with heavy bridge mock-up system and wide visual presentations. In this work, we developed effective 3D object modeling techniques, and constructed virtual harbor scene by using 3D-Webmaster authoring tool. The virtual harbor was built with object-oriented 3D objects modeled to interact with user's action. With the immersion-type VR system, we created virtual harbor environments in a virtual space, and discussed on the naturalness of the scene with test results of SDMPA (Semantic Differential Method for Psychophysical Assessment) by 10 subjects. As the results of subject assessment, all of the participants could felt natural-like harbor. Therefore, we found that the proposed creation methods and procedures of background scene are enabling to fit to the full mission VRSS construction.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.199-207
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• 2002

A virtual laboratory for measurement and instrumentation must aim to realize an integrated environment. To achieve this goal, we designed and implemented a client/server distributed environment and developed a web-based virtual laboratory system for electronic circuits. Since our virtual laboratory system is implemented to describe the on-campus laboratory, the learners can obtain similar experimental data through it. The proposed virtual laboratory system is composed of four important components Principle Classroom, Virtual Experiment Classroom, Evaluation Classroom and Overall Management System. Through our virtual laboratory, the learners will be capable of teaming the concepts and theories related to electronic circuit experiments and how to operate the experimental equipments such as multimeters, function generators, digital oscilloscopes and DC power supplies. Also, every activity occurred in our virtual laboratory is recorded on database and Printed out on the preliminary report form. All of these can be achieved by the aid of the Management System. The database connectivity is made by PHP and the virtual laboratory environment is set up slightly differently for each learner. Finally, we have obtained several affirmative effects such as reducing the total experimental hours and the damage rate for experimental equipments and increasing Loaming efficiencies as well as faculty productivity.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.1
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• pp.60-65
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• 2017

Network virtualization enables us to make efficient use of resources in a physical network by embedding multiple virtual networks in the physical network. In this paper, we develop a prototype of a virtual network embedding system. Our system consists of OpenStack, which is an open source cloud service platform, and shell scripts. Because OpenStack does not provide a quality of service control function, we realize bandwidth reservation for virtual links by making use of the ingress policing function of Open vSwitch, which is a virtual switch used in OpenStack. The shell scripts in our system automatically construct the required virtual network on the physical network using the OpenStack command-line interface, and they reserve bandwidth for virtual links using the Open vSwitch command. Experimental evaluation confirms that our system constructs the requested virtual network and appropriately allocates node and link resources to it.

• Journal of Institute of Convergence Technology
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• v.3 no.2
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• pp.23-29
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• 2013

When a human operator interacts with a virtual wall that is modeled as a virtual spring model, the lager the stiffness of the virtual spring is, the more realistic the operator feels that the virtual wall is. In the previous studies, it is shown that the maximum available stiffness of a virtual spring to guarantee the stability can be increased when the first-order-hold method is applied, however the effects of a human impedance on the stability are not considered. This paper presents the effects of a human impedance on stability of haptic system with a virtual spring and a first-order-hold (FOH) method. The human impedance model is modeled as a linear second-order system model. The relations between the maximum available stiffness of a virtual spring and the human impedance such as a mass, a damping and a stiffness are analyzed through the MATLAB simulation. It is shown that the maximum available stiffness is proportional to the square root of the human mass or damping respectively.

• Journal of Institute of Convergence Technology
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• v.2 no.2
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• pp.35-39
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• 2012

This paper presents the effect of data-hold methods on stability of haptic system with a virtual wall. When a human operator interacts with virtual wall, the lager the stiffness of the virtual wall is, the more realistic the operator feels that the virtual wall is. However, if the stiffness of the virtual wall becomes extremely large, the system may be unstable. When a virtual wall is designed, it is necessary to analyze the maximum available stiffness to guarantee a stable haptic interaction. The simulation model in this paper is developed based on the haptic device model, sampler, a virtual wall model, and data hold methods to compute the maximum stiffness for stability. The effectiveness of the simulation is evaluated through comparing the results of previous studies with the results of this simulation. In addition, the effects of two data hold methods, that is, zero-order hold (ZOH) and first-order hold (FOH) on the stability are analyzed and the values of the maximum available stiffness are compared through the simulation.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.158-159
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• 2005

Three-dimensional(3D) integral imaging system which can be used in a virtual reality system is proposed. The proposed system uses a new image mapping algorithm which can achieve the real time processing, which is indispensable for the virtual reality system. 3D images generated by the advanced graphic software such as OpenGL API can be directly used without complex adaptation. Therefore, the computer-generated integral imaging system using the proposed mapping algorithm can be successfully applied to virtual reality.

• Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.213-222
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• 2014

This paper reviews and identifies issues in the application of virtual commissioning technology for automated manufacturing systems. While the real commissioning of a manufacturing system involves a real plant system and a real controller, the virtual commissioning deals with a virtual plant model and a real controller. The expected benefits of virtual commissioning are the reduction of debugging and correction efforts during the subsequent real commissioning stage. However, it requires a virtual plant model and hence still requires significant amount time and efforts. Two main issues are identified, the physical model construction of a virtual device, and the logical model construction of a virtual device. This paper reviews the current literature related to the two issues and proposes future research directions to achieve the full utilization of virtual commissioning technology.

• Korean Journal of Computational Design and Engineering
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• v.6 no.2
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• pp.140-146
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• 2001

A nuclear Power Plant is composed of a number of mechanical components. Maintaining the integrity of these components is one of the most critical issues in nuclear industry. In order to evaluate the integrity of these mechanical components, a lot of data are required including inspection data, geometrical data, material properties, etc. Therefore, an effective database system is essential to manage the integrity of nuclear power plant. For this purpose, an internet based virtual reality environment and web database system was proposed. The developed virtual reality environment provides realistic geometrical configurations of mechanical components using VRML (Virtual Reality Modeling Language). The virtual reality environment was linked with the web database, which can manage the required data for the integrity evaluation. The proposed system is able to share the information regarding the integrity evaluation through internet, and thus, will be suitable for an integrated system for the maintenance of mechanical components.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.315-320
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• 1999

Obstacle Detection System(ODS) is a essential system for automated vehicle, such as AGV(Automatic Guided Vehicle), mobile robot. Automated vehicle must have a capability to detect and to avoid obstacles to guarantee a safe driving condition. To implement obstacle detection system, virtual bumper concept adapted. Like real bumper in a car, such as in the truck, it protects vehicle from collision using laser distance sensor. When an obstacle(such as other vehicle, building, etc) intrudes this virtual bumper area, a virtual force is calculated and produces necessary strategy to be able to avoid collision. In this paper, simplified virtual bumper concept is presented, and various problems when happens to implement are discussed.