• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.15-20
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• 2003

A method that predicts the flying state of the head slider in an optical disk drive (ODD) or a hard disk drive(HDD) was investigated. The dual solver based on the Newton method and the quasi-Newton method have been developed to simulate the steady-state flying conditions. The numerical results show the effectiveness and reliability of this new solver.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.68-69
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• 2009

Heat Assisted Magnetic Recording (HAMR) is one of the most promising candidates for high density magnetic storages over 1 Tb/$in^2$ areal density. Since the precise light delivery to the head is a key factor to realize HAMR application, it is required to establish the light delivery using micro laser module and micro actuator. For the careful control of micro actuator, a laser module was designed including laser diode, optical fiber, collimating lens, and fabricated V-groove substrate. In addition, the basic aligning method between the laser module and HAMR head was studied by the detection of current change in photo diode due to the amount of reflected light from the head.

• Current Optics and Photonics
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• v.7 no.1
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• pp.54-64
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• 2023

This paper proposes dynamic viewing-zone switching for a binocular holographic three-dimensional display with low interpupil crosstalk and an extended eye-motion box. The optimal pupil geometry for reducing interpupil crosstalk is designed. It is shown that the eye-motion box can be extended by exploiting signal replication in the higher-order viewing zone. Design principles and numerical simulations for verification of the binocular holographic head-up display are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.123-126
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• 2005

Eye Glass Display (EGD) with microdisplay to realize the virtual display can make the large screen, so virtual image has been developed by using microdisplay panel. This paper shows study of low cost lens design and simulation for microdisplay system with 0.6"LCoS panel. Lens design optimized consider to spherical aberration, astigmatism, distortion, and chromatic aberration. Code V is used and it designed an aspheric lens about exit pupil 6mm, eye relief 20mm and 35 degree of field of view (FOV). With the application this aspheric lens to liquid crystal on silicon (LCOS) type's microdisplay, virtual image showed 50 inch at 2m. One side of the aspheric lens was constituted from diffractive optical element (DOE) for the improvement in a performance. It had less than 2.5% of distortion value and modulation transfer function in axial had 20% of resolution with 32 lp/mm spatial frequency. The optical system is suitable for display of 15.6 mm-diagonal with SVGA.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.345-353
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• 2005

We proposed a new and cost-effective method fer assembling holographic pickup modules without any high resolution vision system. Assembling was accomplished by adjusting photodiode package only, leading to a low cost, holographic pickup module. Focus and tracking error signals were simply determined by comparing spot sizes and by using the 3 beam method, respectively, based on four-sectional holographic optical elements. In experiment, we assembled a hologram module and estimated performance of the proposed method fur a holographic pickup module used in compact disc system.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.447-449
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• 1987

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.816-823
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• 2016

This paper studies a light emitting diode(LED) overlapping method of a head-up display that consists of a digital micro device(DMD) panel and a red, green, blue LED in order to increase the brightness of display system and optical output power. This optimization overlapping method removes a quantization noise which occur due to LED overlapping too excessive and stabilizes the junction temperature of LED. In order to reduce junction temperature of LED, the a correlation between a green duty and LED overlapping ratio is studied. Throughout this study, the brightness of head-up display exhibited high increasement ratio of luminance around 33.3 percent at 39 percent overlapping method.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.364-368
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• 1999

We investigate the evaluation items of LSU (Laser Scanning Unit), such as beam size, f$\theta$ characteristics, linearity, skew and bow, optical power ratio between image height of 0mm and $\pm$108 mm, pitch error, Jitter and shift of printing position. Through the measurement of LSU using BSH (Beam Scan Head) installed on LMC (Linear Motion Controller) which moves linearly within the whole scanning range (-108 mm~+108 mm), we can ascertain plastic f$\theta$ lenses, which are manufactured by TVLP (Two-step Variable Low Pressure) molding method, to satisfy 600DPI(Dots Per Inch) performance.

• Journal of Information Display
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• v.11 no.2
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• pp.76-83
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• 2010

This paper presents the multi-user autostereoscopic 3D display system constructed and operated by the authors using the time-multiplexing approach. This prototype has three main advantages over the previous versions developed by the authors: its hardware was simplified as only one optical array is used to create viewing regions in space, a lenticular multiplexing screen is not necessary as images can be produced sequentially on a fast 120Hz LCD with full resolution, and the holographic projector was replaced with a high-frame-rate digital micromirror device (DMD) projector. The whole system in this prototype consists of four major parts: a 120Hz high-frame-rate DMD projector, a 49-element optical array, a 120Hz screen assembly, and a multi-user head tracker. The display images for the left/right eyes are produced alternatively on a 120Hz direct-view LCD and are synchronized with the output of the projector, which acts as a backlight of the LCD. The novel steering optics controlled by the multiuser head tracker system directs the projector output to regions referred to as exit pupils, which are located in the viewers’eyes. The display can be developed in the "hang-on-the-wall"form.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.387-388
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• 2023

PHC pile head cutting is an essential work in pile foundation construction. However, since the work has labor-intensive characteristics, there are problems such as productivity and safety. So in previous study PHC pile one-cutting head cutting automation equipment was developed to solve this problem. However, it has been investigated as a limitation that checking the cutting position of the PHC pile can be challenging in place where a rotary laser leveler cannot irradiate cutting position, as the sensing unit of the developed automated equipment utilizes an optical method. Therefore, the objective of this study is to delvelop a GNSS-based methodology for sensing the cutting position of PHC piles to overcome the limitations of the optical method and to examine its feasibility for field application. If the proposed methodology is applied to the construction site, it is expected that the convenience and productivity of the PHC pile cutting position sensing work will be improved.