• 한국전자파학회논문지
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• 제17권2호
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• pp.207-212
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• 2006

현재 다양한 종류의 무선 단말기가 상용화 되어 있다. 그러나 연구의 대부분이 휴대폰에 의한 생체 영향에만 국한되어 있는 실정이다. 본 논문에서는 두부 착용형과 손목 착용형 같은 인체 착용형 단말기에 대한 인체 영향을 분석하였다. 외국인 성인 모델과 한국인 성인 모델 그리고 외국인 청소년 모델을 대상으로 FDTD 기법을 적용하여 SAR을 계산하였다. 또한 시뮬레이션 결과를 검증하기 위해 간단한 구조의 head-mounted display 장치에 대한 노출량을 SAM 팬텀을 이용하여 측정하였다. 노출량 평가 결과 인체 착용형 단말기 노출에 대해 어린이가 더 취약한 것으로 나타났으며 이러한 기기가 휴대폰에 비해 출력이 상대적으로 낮음에도 불구하고 인체에 영향을 미칠 수도 있는 것으로 평가되었다.

• International journal of advanced smart convergence
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• 제6권4호
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• pp.80-87
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• 2017

Mixed Reality (MR) shows a composite image of a virtual object in the real world. It has been applied to various fields by the introduction of head mounted display (HMD) such as Microsoft's Hololens [1-3]. The virtual studio in broadcasting combines the contents created by computer graphics with the actual set to reproduce the 3D image screen. This requires physical space such as a set of chroma keys. It also requires professional knowledge and manpower and costly equipment to post-process the graphics and information for long periods of time. Therefore, in this paper, we aim to study the implementation of virtual studio based on Mixed Reality using Microsoft Hololens. Through the implementation of 'Holo-studio' application, realistic and virtual objects of broadcasting camera viewpoint were acquired at the same time. Using Microsoft's spectator view library, the frame rate is degraded in objects with high polygons (100,000 polygons). The proposed method maintains 60 fps image transmission in high polygon objects. The results of this paper show the possibility of using virtual studio at low cost which does not need separate physical space.

• Educational Technology International
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• 제18권1호
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• pp.49-71
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• 2017

The purpose of the study was to identify key design features of virtual reality with head-mounted displays (HMD) and touchless interface for the hearing-impaired and hard-of-hearing learners. The virtual reality based training program was aimed to help hearing-impaired learners in machine operating learning, which requires spatial understanding to operate. We developed an immersive virtual learning environment prototype with an HMD (Oculus Rift) and a touchless natural user interface (Leap Motion) to identify the key design features required to enhance virtual reality for the hearing-impaired and hard-of-hearing learners. Two usability tests of the prototype were conducted, which revealed that several features in the system need revision and that the technology presents an enormous potential to help hearing-impaired learners by providing realistic and immersive learning experiences. After the usability tests of hearing-impaired students' exploring the 3D virtual space, interviews were conducted, which also established that further revision of the system is needed, which would take into account the learners' physical as well as cognitive characteristics.

• 디지털콘텐츠학회 논문지
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• 제19권7호
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• pp.1237-1244
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• 2018

현재 가상현실 상용화의 문제점은 사람들이 가상현실을 체험하기 위해서는 수십만 원을 호가하는 가상현실 장비들이 필요하다는 것과 가상현실을 즐길 만한 콘텐츠가 부족하다는 것이다. 이러한 문제를 해결하기 위하여 스마트폰과 PC를 활용하여 별도의 비용 없이 HMD(Head Mounted Display)의 기능을 구현하고 무선으로 가상현실 시스템을 구축하는 것이 본 논문의 목표이다. 가상현실은 많은 양의 데이터 처리를 요구하기 때문에 PC에서 데이터를 처리하고, 스마트폰의 디스플레이와 내장 센서를 이용하여 PC와의 데이터 송수신을 통해 HMD의 기능을 구현하였다. 또한 무선 컨트롤러를 제작하여 사용자의 움직임을 자유롭게 하였다. 본 논문에서 구현한 시스템의 테스트를 위해 콘텐츠를 제작하여 실험하였다. 이를 통하여 사용자는 고가의 장비 없이 기존에 보유하고 있던 스마트폰과 PC를 이용하여 가상현실을 체험할 수 있으며, 기존의 유선환경에서 벗어나 무선 환경에서 가상현실을 체험할 수 있다. 이렇게 가상현실을 쉽게 접함으로써 사용자가 증가하면 개발에 많은 투자가 됨에 따라 가상현실 기술 발전과 상용화에 많은 진전이 있을 것으로 기대된다.

• Current Optics and Photonics
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• 제1권5호
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• pp.474-490
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• 2017

Since the recent slowdown in the smartphone market, studies for wearable devices are briskly being carried out to find new markets, such as virtual reality devices. In this paper, a head-mounted display (HMD) which provides expanded virtual images before human eyes by enlarging images of a small display was designed, and the tolerance analysis method for a focus-adjustable HMD based on afocal optical systems was studied. There are two types of HMDs: a see-through type that allows the user to view the surroundings, and a see-close type where the user can only view the display screen; the former is used in this study. While designing the system, we allowed a lens within the system to be shifted to adjust its focus from +1 to -4 D (diopters). The yield of the designed systems was calculated by taking the worst-case scenario of a uniform distribution into account. Additionally, a longitudinal aberration was used rather than MTF for the tolerance analysis with respect to system performance. The sensitivity of the designed system was calculated by assigning a certain tolerance, and the focus lens shift was calculated to adjust the image surface variations resulting from the tolerance. The smaller the tolerance, the more expensive the unit price of the products. Very small tolerances may even be impossible to fabricate. Considering this, the appropriate tolerance was assigned; the maximum shift of the focus lens in which the image surface can be adjusted was obtained to find the changes in aberration and a good yield.

• 한국게임학회 논문지
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• 제17권4호
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• pp.55-62
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• 2017

본 연구에서는 HMD(Head Mounted Display)를 가지고 Walk-through의 이동시뮬레이션에 대한 평가를 실시하였다. 구체적으로는 VR공간 주변에 배치된 오브젝트 밀집정도(밀도)의 변화가 심리적 이동거리, 이동속도, 이동시간에 어떠한 영향을 미치는지 알아보았다. 연구결과 첫째, 실험 조건 (저밀도, 중밀도, 고밀도)에 있어 조건간의 차이는 모두 유의미하였다. 둘째, 주변 오브젝트의 밀도가 높아질수록 이동시간, 이동속도, 이동거리가 기본조건과 비교하여 평균점이 높게 나타났다. 셋째, 주변의 오브젝트가 VR공간의 이동시뮬레이션에 있어 시간, 속도, 거리의 감각을 향상 시키는 것을 확인하였다.

• The Journal of Korean Physical Therapy
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• 제31권5호
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• pp.273-278
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• 2019

Purpose: The purpose of this study was to investigate the effects of three-dimensional virtual reality horse riding simulator training using a head-mounted display on gait and balance in children with cerebral palsy. Methods: Ten children with cerebral palsy were randomly assigned to the horse riding simulator (HRS) group (n=5) or the horse riding simulator with virtual reality (HRSVR) group (n=5). To evaluate balance, center of gravity (COG) sway velocity and total sway distance of each group were assessed using the Wii balance board, and gait speed and stride length of each group were assessed using a gait analysis system. Results: Intra-group comparisons between pre- and post-intervention measures revealed that there were significant changes in all gait and balance variables such as stride length, gait velocity, COG sway velocity and COG sway distance in the HRSVR group (p<0.05). In the HRS group, there were significant changes in all variables except stride length (p<0.05). In addition, inter-group comparisons showed significant differences between the two groups in stride length, gait velocity and COG sway distance except COG sway velocity (p<0.05). Conclusion: The findings of this study suggest that horse riding simulator training combined with 3D virtual reality can be a new positive therapeutic approach for improving functional performance in children with cerebral palsy.

• 방송과미디어
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• 제16권2호
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• pp.73-83
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• 2011

홀로그래픽 광학소자(HOE; holographic optical elements)는 높은 회절효율과 협대역 주파수 특성, 그리고 여러 가지 기능을 하나의 소자로 구현할 수 있다는 특성을 갖고 있어 비행기와 자동차의 정보 표시를 위한 HUD(head-up display), 증강현실용 HMD(head mounted display), 2D/3D 디스플레이용 스크린 등에 널리 활용되고 있다. 이에 홀로그래픽 광학소자(HOE)의 동작특성과 디스플레이에 활용되고 있는 몇 가지 예를 통해 그 활용가치와 앞으로 홀로그래픽 광학소자가 좀 더 보편화되기 위해 풀어야 할 당면과제 등에 대해 다루고자 한다.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.495-503
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• 2016

The purpose of this study is to develop the education content that induce energetically the adolescent's participation and learning for the education of suicide prevention. In order to realize it, we suggested the novel education methods based on virtual reality and HMD (Head Mounted Display), and developed the prototype system. This study intends to evaluate the effect of the proposed prototype system as a new education method with experiment and survey. This approach can show us the different possibility of adolescent's suicide prevention education.

• 한국컴퓨터정보학회논문지
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• 제23권7호
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• pp.57-62
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• 2018

In this paper, we propose an improved algorithm for rendering method to guarantee frame rates based on HMD (Head Mounted Display) motion in an avionics simulator. One of important issues in HMD simulators is to guarantee frame rates despite fast motion of HMD which is more rapid than the aircraft's moving speed to maintain a quality of images. Therefore, we propose an algorithm considering the moving speed of a pilot's head: Improved Speed-Based LOD (Level-Of-Detail) Control (ISBLC). In the proposed algorithm, frame rates are improved by changing dynamic LOD which determines details of objects for rendering images. Throughout the experiments, we show the average frame rates are achieved up to 60 and minimum frame rates are guaranteed up to 40. The proposed algorithms will be used HMD simulation in avionics simulators.