• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1008-1013
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• 2003

This paper concerns the structural characteristic analysis and evaluation on the hydrostatic guide way and feeding system of a high precision centerless grinder for machining ferrules. In order to realize the required accuracy of ferrules with sub-micron order, the axial stiffness and motion accuracy of feeding system have to become higher level than those of existing centerless grinders. Under these points of view, the physical prototype of feeding system consisted of steel bed, hydrostatic guide way and ballscrew feeding mechanism is designed and manufactured for trial. Experimental results show that the axial and vertical stiffnesses of the physical prototype are very low as compared with those design values. In this paper, to reveal the cause of these stiffness difference, the structural deformations on the virtual prototype of feeding system are analyzed based on the finite element method under experimental conditions. The simulated results illustrate that the deformation of front ballscrew support-bearing bracket is the main cause of reduction in the axial stiffness of feeding system, and the deflection of bed structure and the bending deformation of hydrostatic guide rails are the main causes of reduction in the vertical stiffness of feeding system.

• 대한기계학회논문집A
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• 제28권7호
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• pp.896-903
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• 2004

This paper proposes the structural characteristic analysis and evaluation on the hydrostatic guide way and feeding system of a high-precision centerless grinder for machining ferrules. In order to realize the required accuracy of ferrules with sub-micron order, the axial stiffness and motion accuracy of feeding system have to become higher level than those of existing centerless grinders. Under these points of view, the physical prototype of feeding system composed of steel bed, hydrostatic guide way and ballscrew feeding mechanism is designed and manufactured for trial. Experimental results show that the axial and vertical stiffnesses of the physical prototype are very low as compared with those design values. In this paper, to reveal the cause of these stiffness difference, the structural deformations on the virtual prototype of feeding system are analyzed based on the finite element method under experimental conditions. The simulated results illustrate that the deformation of front ballscrew support-bearing bracket is the main cause of reduction in the axial stiffness of feeding system, and the deflection of bed structure and the bending deformation of hydrostatic guide rails are the main causes of reduction in the vertical stiffness of feeding system.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
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• pp.203-207
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• 2005

종래의 문화유산 디지털 아카이브는 사지이나 자료를 디지털화하여 보관되고 있는 것이 대부분이었으나, 최근에는 3차원 컴퓨터 그래픽을 이용한 3차원 디지털 아카이브의 구축이 확산되고 있다. 이러한 차원에서, 본 연구는 가상현실(Virtual Reality:VR)기술을 이용한 3차원 디지털 아카이브 열람 시스템의 개발에 관한 내용들로 구성되어 있다. 본 연구의 목적은, 이용자가 보존된 아카이브의 열람을 통하여 문화유산을 보다 쉽게 이해하고 지식을 습득할 수 있는 시스템의 개발이다. 시스템 개발에 활용된 기술은 DirectX기술의 가상현실이며, 각 콘텐츠의 이해를 돕기 위하여 두 가지 이상의 콘텐츠를 같은 화면에 제시하여 비교하면서 볼 수 있는 인터페이스를 개발하였다. 이러한 시스템은 터키공화국의 Gemiler섬에 있는 교회의 데이터를 이용하여 현재 남아있는 유적과 창건당시의 모습을 복원하여 비교하면서 콘텐츠에 대한 이해를 높이고 보다 많은 지식을 얻을 수 있도록 구축되었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.21-23
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• 2019

본 연구는 안구 피로 감소를 위해 VR 기기 프로토타입을 개발하고자 한다. VR 기기가 대중화되면서 안구 피로를 호소하는 사례들이 빈번해지고, 더 나은 미래를 위해서 VR 기기의 문제점을 잘 보완하고 정비하여 4차 산업혁명의 빠른 속도와 역동적인 환경을 편한 마음으로 누릴 수 있길 바란다. 본 연구에서는 VR 기기에 대한 설명, 안구 피로 관련사례, 안구 피로 감소를 위한 타임아웃 센서 및 안구마사지 기능이 있는 VR 기기를 디자인 하였고 VR 기기 프로토타입을 개발하였다. 이러한 기능들은 인체에 유해한 전자파를 차단하여 장시간 사용해도 피로감을 줄이는데 도움을 줄 수 있을 것이며, 앞으로 VR의 미래가 발전될 수 있을 것이다.

• 한국CDE학회논문집
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• 제12권1호
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• pp.15-26
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• 2007

We have developed a method that enables a user to better understand and enjoy the contents of 3D digital archives, thereby enhancing the user's experience. The system's interactive interface, built using virtual reality technology, enables the user to "walk through" the archives, comparing two or the same content at different points in time. For example, a user can compare the proposed design for a building with the actual building and can compare the states of restoration of a cultural heritage site over time. This ability to perform multilateral comparisons enables the user to clarify the relationship between contents, the influence of one content on another, and the causal relationship between contents. Testing of a prototype system for a 3D digital archive of cultural heritage sites showed that it worked smoothly and that the users could easily operate the navigation system.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.1-5
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• 2009

본 연구에서는 몰입형 인간 컴퓨터 상호작용을 위한 햅틱 마우스 시스템을 제작한다. 제작한 햅틱 마우스는 진동감각 뿐 아니라 온열감도 제공하기 때문에 사용자는 더욱 몰입감 있게 가상의 공간을 경험할 수 있다. 진동 감각과 온열감을 제공하기 위하여 편심모터들과 솔레노이드, 그리고 펠티어 엑츄에이터를 이용하였으며 제작한 시스템의 평가를 위하여 레이싱 게임 프로토타입을 구현하여 테스트를 수행한다. 실험결과로부터 본 햅틱 마우스는 가상 공간에서 사용자에게 사실감을 전달함을 알 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1722-1741
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• 2017

Intrusion detection techniques based on virtual machine introspection (VMI) provide high temper-resistance in comparison with traditional in-host anti-virus tools. However, the presence of semantic gap also leads to the performance and compatibility problems. In order to map raw bits of hardware to meaningful information of virtual machine, detailed knowledge of different guest OS is required. In this work, we present VDSM, a lightweight and general approach based on driver separation mechanism: divide semantic view reconstruction into online driver of view generation and offline driver of semantics extraction. We have developed a prototype of VDSM and used it to do intrusion detection on 13 operation systems. The evaluation results show VDSM is effective and practical with a small performance overhead.

• Journal of Power Electronics
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• 제13권5호
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• pp.787-797
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• 2013

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.93-102
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• 2010

Shaping realistic hairstyles for digital characters is a difficult, long and tedious task. The lack of appropriate interaction metaphors enabling efficient and simple, yet accurate hair modeling further aggravates the situation. This paper presents 3D interaction metaphors for modeling virtual hair using haptic interfaces. We discuss user tasks, ergonomic aspects, as well as haptics-based styling and fine-tuning tools on an experimental prototype. In order to achieve faster haptic rates with respect to the hair simulation and obtain a transparent rendering, we adapt our simulation models to comply with the specific requirements of haptic hairstyling actions and decouple the simulation of the hair strand dynamics from the haptic rendering while relying on the same physiochemical hair constants. Besides the direct use of the discussed interaction metaphors in the 3D modeling area, the presented results have further application potential in hair modeling facilities for the entertainment industry and the cosmetic sciences.

• 한국CDE학회논문집
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• 제19권4호
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• pp.423-433
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• 2014

For the proper decision making and responsibility enhancement for an unexpected accident in large-scale facilities, it is important to train operators or first responders to minimize potential human errors and consequences resulted from them. Simulation technologies, including human-computer interaction and virtual reality, enables personnel to participate in simulated hazardous situations with a safe, interactive, repetitive way to perform these training activities. For the development of accident response training simulator, it is necessary to define components comprising the simulator and to integrate them for the given training purpose. In this paper, we analyze requirements of the training simulator, derive key components, and design the training simulator. Based on the design, we developed a prototype training simulator and verified the simulator through experiments.