• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2009년도 추계학술대회 논문집
• /
• pp.735-736
• /
• 2009

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -1
• /
• pp.450-453
• /
• 2002

In this paper a Phase-based virtual image encryption and decryption techniques based on a joint transform correlator (JTC) are proposed. In this method, an encrypted image is obtained by multiplying a phase-encoded virtual image that contains no information from the decrypted image with a random phase. Even if this encryption process converts a virtual image into a white-noise-like image, the unauthorized users can permit a counterfeiting of the encrypted image by analyzing the random phase mask using some phase-contrast technique. However, they cannot reconstruct the required image because the virtual image protects the original image from counterfeiting and unauthorized access. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. In addition, the reconstructed data can be directly transmitted to a digital system for real-time processing. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

• 전력전자학회논문지
• /
• 제4권5호
• /
• pp.455-461
• /
• 1999

본 논문에서는 가상환경 내의 물체로부터 역감을 얻을 수 있는 3자유도 힘 반향 장치를 제안한다. 이 시스템은 디바이스와 가상환경의 모델과 힘 반향 렌더링 알고리즘 등으로 구성되었다. 평행링크 메커니즘과 와이어에 의한 토크전달 그리고 임피던스 제어가 가능한 제어기를 사용해 3자유도 힘 반향 역감장치(Force-reflecting device)를 설계하였다. 위치 함수만으로 계산되는 힘 반향동작은 God-Object 알고리즘을 사용했다. 3차원 가상물체와 시험 제작한 역감장치(Force-reflecting device)를 인터페이스 실험을 통해 3차원 가상물체와 접촉과 비접촉 그리고 푸쉬 버튼을 만지는 느낌을 검출하였다.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2003년도 춘계학술대회 논문집
• /
• pp.94-100
• /
• 2003

Patients with schizophrenia have thinking disorders such as delusion or hallucination, because they have a deficit in the ability which to systematize and integrate information. Therefore, they cannot integrate or systemize visual, auditory and tactile stimuli. In this study we suggest a virtual reality system for the assessment of cognitive ability of schizophrenia patients, based on the brain multimodal integration model. The virtual reality system provides multimodal stimuli, such as visual and auditory stimuli, to the patient, and can evaluate the patient's multimodal integration and working memory integration abilities by making the patient interpret and react to multimodal stimuli, which must be remembered for a given period of time. The clinical study showed that the virtual reality program developed is comparable to those of the WCST and the SPM.

• International Journal of Precision Engineering and Manufacturing
• /
• 제4권2호
• /
• pp.71-76
• /
• 2003

A virtual machine tool (VMT) is presented in this two-part paper. In Part 1, the analytical foundation for a virtual machining system is developed, which is envisioned as the foundation for a comprehensive simulation environment capable of predicting the outcome of cutting processes. The VHT system undergoes "pseudo-real machining", before actual cutting with a CNC machine tool takes place, to provide the proper cutting conditions for process planners and to compensate or control the machining process in terms of the productivity and attributes of the products. The attributes can be characterized by the machined surface error, dimensional accuracy, roughness, integrity, and so forth. The main components of the VMT are the cutting process, application, thermal behavior, and feed drive modules. In Part 1, the cutting process module is presented. When verified experimentally, the proposed models gave significantly better prediction results than any other methods. In Part 2 of this paper, the thermal behavior and feed drive modules are developed, and the models are integrated into a comprehensive software environment.vironment.

• 한국공작기계학회논문집
• /
• 제17권6호
• /
• pp.83-90
• /
• 2008

Input shaping is an efficient tool to eliminate transient and residual vibration caused by motion of mechanical systems. However, the rise time of the systems tends to increase due to the presence of input shapers. This paper is concerned with the rise time reduction when using input shaping. To this end, this paper proposes an input shaper design method for an undamped single mode vibration system using a virtual mode, which is not an actual mode but reflected in the design process. The essence of the proposed method is to design a three-impulse input shaper as if a single mode system has two modes: one actual mode and one virtual mode. The natural frequency of the virtual mode is a design parameter to change the rise time of the system. This paper discusses the performance of the proposed input shapers by simulation.

• 한국컴퓨터그래픽스학회논문지
• /
• 제3권1호
• /
• pp.29-36
• /
• 1997

기존의 많은 가상현실시스템은 단일 사용자를 위한 단일 시스템으로 개발되었다. 그러나 최근의 증가 되는 인터넷등 통신망의 이용가치로 인해 많은 사람들이 분산 가상 현실- 네트워크를 통해 다수의 참여자가 상호작용을 공유하는 가상 환경- 기술에 큰 관심을 가지게 되었다. 본 연구에서는 LAN상에서 가상환경과 상호작용을 공유하기 위해서 3차원 가상세계표현화 네트워크 모델에 관한 연구를 하였다. 상호작용이 가능한 3차원 가상세계표현은 멀티유저 환경을 지원하도록 확장한 VRML을 기반으로 하였고 네트워크 모델은 IP멀티캐스트 환경하에서 멀티유저와 상호작용을 지원하고 3차원 가상 세계를 공유하도록 하는 구조와 프로토콜로 구성되었다.

• 한국전자통신학회논문지
• /
• 제7권2호
• /
• pp.279-285
• /
• 2012

전력, 수력, 원자력, 석유 등 국가에서 관리하는 중요핵심기반시설들은 대부분 SCADA(Supervisiory Control And Data Acquisition)시스템의 폐쇄망 형태로 운영되고 있다. 이러한 시스템들은 개방형 프로토콜 및 상용 운영체제 사용 등으로 인해 점차 IT에 대한 의존성이 증가되는 추세이다. 이러한 주요 시설들이 사이버 테러 및 해킹, 바이러스 등에 의해 원격 조작 및 통제되는 경우 심각한 위험에 빠질 수 있다. 본 논문에서는 주요기반시설 시스템에 대한 위협 및 취약성을 최소화하는 방법을 제시하고, 공격패턴이 알려지지 않은 Zero-Day Attack을 탐지하는 Virtual Honeynet의 시스템 구성과 공격 탐지 알고리즘, 탐지 사례 등에 대해 알아보고자 한다.

• 한국정밀공학회지
• /
• 제18권11호
• /
• pp.74-79
• /
• 2001

In this two-part paper, a virtual machine tool (VMT) is presented. In part 1, the analytical foundation of a virtual machining system, envisioned as the foundation for a comprehensive simulation environment capable of predicting the outcome of cutting processes, is developed. The VMT system purposes to experience the pseudo-real machining before real cutting with a CNC machine tool, to provide the proper cutting conditions for process planners, and to compensate or control the machining process in terms of the productivity and attributes of products. The attributes can be characterized with the machined surface error, dimensional accuracy, roughness, integrity and so forth. The main components of the VMT are cutting process, application, thermal behavior and feed drive modules. In part 1, the cutting process module is presented. The proposed models were verified experimentally and gave significantly better prediction results than any other method. The thermal behavior and feed drive modules are developed in part 2 paper. The developed models are integrated as a comprehensive software environment in part 2 paper.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2002년도 추계학술대회 논문집
• /
• pp.187-192
• /
• 2002

Research has shown that many smokers experience an increase in the desire to smoke when exposed to smoking-related cues. Cue exposure treatment (CET) refers to the manualized, repeated exposure to smoking-related cues, aimed at the reducing cue reactivity by extinction. In this study, we constructed a virtual reality system for evoking a desire of nicotine, which was based on the results of a Questionnaire of Nicotine-craving. And we investigated the effectiveness of the virtual reality system as compared to classical device (pictures). As a result, we reached the conclusion that virtual reality elicits more craving symptoms than the classical devices.