• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.782-788
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• 2018

This paper proposes a novel method for the omnidirectional camera-based image rendering synchronization system using head mounted display. There are two main processes in the proposed system. The first one is rendering 360-degree images which are remotely photographed to head mounted display. This method is based on transmission control protocol/internet protocol(TCP/IP), and the sequential images are rapidly captured and transmitted to the server using TCP/IP protocol with the byte array data format. Then, the server collects the byte array data, and make them into images. Finally, the observer can see them while wearing head mounted display. The second process is displaying the specific region by detecting the user's head rotation. After extracting the user's head Euler angles from head mounted display's inertial measurement units sensor, the proposed system display the region based on these angles. In the experimental results, rendering the original image at the same resolution in a given network environment causes loss of frame rate, and rendering at the same frame rate results in loss of resolution. Therefore, it is necessary to select optimal parameters considering environmental requirements.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.200-201
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• 2001

헬멧 장착형 HMD(Head-Mounted Display) 시스템은 비행기 조종사나 저격수의 시선을 크게 움직이지 않고 군사 전술상의 현재 상태를 볼 수 있도록 하여 눈의 피로감을 줄이고 시선의 이동에 의한 돌발적인 사고의 위험을 감소시킬 수 있어 군사적으로 유용한 장치이다 HOE(Holographic Optical Element)의 중요한 응용 분야 중 하나로 HMD에서의 결상 렌즈 또는 광 결합기가 있다 HMD 시스템에서 HOE의 역할은 2차원의 단색 디스플레이 영상을 헬멧 착용자의 눈에 반사하여 결상시키는 것이다. (중략)

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.70-77
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• 2017

Dynamic visual acuity is used as an important factor to measure athletic performance in sports field. A study on visual acuity testing system using non-see head mounted display (NST-HMD) was conducted recently. However, the NST-HMD has a problem that the sense of space felt by the subject differs from the actual environment. This is because the view is blocked so that it is only implemented in a virtual space. This paper proposes a dynamic visual acuity testing system using optical see through head mounted display (OST-HMD). To do this, OST-HMD and NST-HMD comparative tests were conducted using existing K-D (King-Devick) charts. Experiments were performed on 30 subjects and their visual acuity was measured and analyzed by parametric statistics and one-sample T-test. The results of the study demonstrate the effectiveness of the proposed OST-HMD. This study is expected to use the visual inspection and training equipment of OST-HMD.

• Korean Journal of Optics and Photonics
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• v.12 no.6
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• pp.512-518
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• 2001

In this paper, the geometrical properties of the optical system for Head Mounted Display (HMD) were investigated. Also, this work deals with the concept for an optical system design bated on Diffractive Optical Elements (DOE). In designing the optical system for HMD, it is considered that the optical system should have compact, high performance, and comfortable properties while user sees the picture. In order to satisfy these requirements, we applied DOE and aspheric surfaces to the lens so that correction of color and monochromatic aberrations could be obtained. Also, the design and evaluation for the optical system were carried out using the generalized model of the human eye. Finally, it was expected to fulfill all the requirements of an HMD system.

• Science of Emotion and Sensibility
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• v.19 no.3
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• pp.71-80
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• 2016

The purpose of this study was to examine the effects of display on time on tasks and virtual presence in the immersive virtual reality. Head mounted display (HMD) and monitor conditions were compared when the participants were asked to complete navigation tasks in a virtual classroom. Time on tasks and virtual presence were measured. Three factors of the virtual presence were applied as dependent variables such as 1) spatial presence, 2) involvement, and 3) realness. The results showed that HMD condition took longer time to finish tasks than monitor conditions. HMD condition showed significantly higher perception from all of the virtual presence factors. Interestingly, there was a significant interaction effect between the display conditions and presence factors. The relationship between display types and virtual presence factors were discussed for future study.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.236-243
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• 2003

We discussed the design of lens module schematic eyes equivalent to finite model eyes, which are used to model the human eye based on spherical aberration and Stiles-Crowford effect. The optical system for head mounted display (HMD) is designed and evaluated using lens module schematic eyes. In addition to a compact HMD system, an optical system with high Performance is required. To satisfy these requirements, we used diffractive optical elements and aspheric surfaces so that the color and mono-chromatic aberrations were corrected. The optical system for HMD is composed of 0.47 inch micro-display of SVGA grade with 480,000 pixels, a plastic hybrid lens for the virtual image, and the lens module schematic eyes. The designed optical system fulfills the current specifications of HMD: such as, EFL of 31.25 mm, FOV of 24H$\times$18V$\times$30D degrees, and overall length of 59.1 mm. As a result, we could design an optical system useful for HMD; the system is expected to be comfortable while the user wears it.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.1-9
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• 2018

A keyboard system for hands-free virtual reality head mounted display using electrooculogram (EOG) signal which occurs during the eye-blinking is proposed. This system consists of display device, gyroscope sensor, gravity sensor and electro-encephalogram (EEG) sensor, and it is implemented with Unity3D engine for system control and graphic processing. If the input language of proposed keyboard system is Korean, i.e. Hangul, the Chonjiin keyboard method is utilized; but for the English spelling, numbers or special characters, $3{\times}4$ keyboard method is used in order to solve the spatial problem. By the implemented method, it can be verified that the user can handle the keyboard input of virtual reality head mounted display with only neck movement and EOG, instead of using hands.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.149-155
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• 2017

Objective: The purpose of this study was to investigate the effects of three visual conditions (eyes opened, eyes closed, and wearing of a head mounted display [HMD]) on single-leg standing through kinematics and kinetic analysis. Method: Twelve college students (age: $24.5{\pm}2.6years$, height: $175.0{\pm}6.4cm$, weight: $69.2{\pm}5.1kg$) participated in this study. The study method adopted three-dimensional analysis with six cameras and ground reaction force measurement with one force plate. The analysis variables were coefficient of variation (CV) of the center of body mass, head movement, ground reaction force, and center of pressure, which were analyzed using one-way analysis of variance with repeated measures according to visual conditions. Results: In most cases, the results of this study showed that the CV was significantly higher in the order of HMD wearing, eyes closed, and eyes opened conditions. Conclusion: Our results indicated that body sway was the largest in the HMD wearing condition, and the risk of falling was high owing to the low stability.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.52-57
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• 2019

Studies to augment emotion and immersion in multimedia content through olfactory stimulation are being increasingly conducted in the past two decades, and a variety of scent devices have been developed. Most of the scent devices are very large and heavy; consequently, they are installed on a table rather than being attached to the Head-mounted Display (HMD). Even if such devices are mounted on the HMD, it is not possible to control the scent density because of the size limitation, and it is not easy to be immersed in the experience because of the noise caused by the scent device. In order for an actual virtual reality or an augmented reality system to work efficiently with the scent device, three conditions - noiseless, a compact design, and concentration control- must be satisfied. In this study, we design a scent device that satisfies these three conditions. By using a miniature piezoelectric pump, a small size scent device is designed so that it can be easily attached to the lower end of the HMD, and hardly any noise is generated. Moreover, it is possible to control the concentration of the scent by controlling the piezoelectric pump using amplitude and frequency.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.234-238
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• 2016

A new method to design a low distortion, even relative illumination, optical see-through head-mounted display (HMD) with a freeform reflective mirror (FFRM) based on the two similar ellipsoids structure is proposed. The HMD we have realized has a simple structure which consists of two similar ellipsoid surfaces, an FFRM, a 7-piece co-axis relay lens, and an OLED. This structure can be applied to offset distortion, reach even relative illumination, and correct the off-axis aberrations. The HMD we finally have realized has a near 3% low distortion, a higher than 80% relative illumination, and a 40°×30° field of view (FOV).