• Korea-Australia Rheology Journal
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• 제15권4호
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• pp.167-171
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• 2003

The backlight unit (BLU) is used as a light source of TFT liquid-crystalline-display (TFT-LCD) module. In this backlight unit, one of important components is the light guide, which is usually made of transparent polymers. Currently, the screen-printing method is mainly used for the light guide as a manufacturing process. However, it has limitation to the flexibility of three-dimensional optical design. In the present paper a new alternative manufacturing method for the light guide with low-cost is proposed. This manufacturing method is named as direct surface forming (DSF), which is very similar to the well-known hot embossing except for partial contact between mold and substrate. The results of this new manufacturing method are presented in terms of processing condition, dimensional accuracy, productivity, etc.

• Korean Journal of Optics and Photonics
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• 제13권1호
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• pp.27-31
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• 2002

We design a 1$\times$4 optical splitter made of photonic crystal waveguides and analyze the properties of the optical splitter using the finite-difference time-domain method with perfectly-matched-layer absorbing boundaries. The photonic crystal is constructed from cylindrical rods in air on a square lattice. Our simulation results show that there are different transmission properties for four bend geometries and different incident-wave frequencies. The sum of the power transmission of the splitted light is over 93 percent at a certain geometry and frequency, and the incident power splits in the four arms with almost the same ratio.

• Korean Journal of Optics and Photonics
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• 제13권1호
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• pp.21-26
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• 2002

In the conventional star coupler, a certain amount of loss should be expected because lateral diffraction is used for the power distribution. In this paper, we propose a new design of a low loss star coupler which employs UV-written tapered waveguides and an AWG based on the low loss star couplers, and investigate their various characteristics. The loss of the UV-written star coupler is lower than that of the conventional star coupler, and the AWG device based on the UV-written star couplers shows low loss characteristics.

• Journal of Korean Ophthalmic Optics Society
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• 제9권1호
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• pp.43-51
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• 2004

The purpose of this study was to investigate the present business management strategy of optician's stores for their improvement and development so that they directly related to consumers in the sale channel of eyeglasses are retailing business. For this purpose, it attempted to investigate the present state and business management problem of optical stores in korea. We wish to present problem and improvement direction on optician's stores condition and administration management, and show useful operation method in optician's stores.

• Current Optics and Photonics
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• 제1권3호
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• pp.233-238
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• 2017

In this paper we propose a freeform secondary lens for an LED fishing/working lamp (LFWL). This innovative LED lamp is used to replace the traditional HID fishing lamp, to satisfy the lighting demands of fishing and the on-board activities on fishing boats. To realize the freeform lens's geometry, Gaussian decomposition is involved in our optics-design process for approaching the targeted light intensity distribution curve (LIDC) of the LFWL lens. The simulated results show that the illumination on the deck, on the sea's surface, and underwater shows only small differences between LED fishing/working lamps and HID fishing lamps. Meanwhile, a lighting efficiency of 91% with just one third of the power consumption can be achieved, when the proposed LED fishing/working lamps are used instead of HID fishing lamps.

• International Journal of Advanced Culture Technology
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• 제6권3호
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• pp.201-210
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• 2018

We constructed 3-D images by HMD (Head Mount Display) type and polarization technique through which a training instrument of binocular function based on clinical vision therapy was developed and investigated its demand. To design the instrument that performs Test- Diagnosis - (Prescription) - Training - Treatment we provided a customized training method for the trainers using optical IT instruments of binocular test. Through the contents and the instruments of the vision therapy technology developed in this work we can replace the current vision test instruments to those costing 60% lower price in eye clinics and eye glasses shops. By replacing the existing vision test instruments it is possible to create a new market of the vision therapy in vision training instruments.

• Journal of the Korean Vacuum Society
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• 제2권2호
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• pp.145-151
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• 1993

Ultra High Vacuum chamber for surface analysis and a series of AES-LEED controllers for LEED optics was designed and constructed. Electron energy resolution of LEED optics was tested. On the basis of the layer by layer mode, thickness of evaporated Ni on Pt(111) was calculated from the Auger signal ratio.

• ETRI Journal
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• 제30권4호
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• pp.615-617
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• 2008

A novel and compact elliptic-function bandpass filter is proposed in this letter. The techniques of slot etching and the addition of open stubs are applied to enhance the self-inductance and self-capacitance of hexagonal open-loop resonators. Thus, size reduction and improved transmission performance are obtained. Compared to the performance of the conventional design, the central frequency and insertion loss are reduced by 28% and 3.1 dB, respectively. Measurements show that the proposed filter has a fraction bandwidth of 23% at the central frequency of 1.84 GHz, and its insertion loss in the passband is less than -1.5 dB. The bandpass filter occupies only 12 mm${\times}$21.2 mm (approximately $0.24{\lambda}_g{\times}0.14{\lambda}_g$).

• Korean Journal of Optics and Photonics
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• 제12권5호
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• pp.382-388
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• 2001

KITSAT-3, launched at May 26 1999, has an earth observation optical payload named MEIS (Multi-spectral Earth Imaging System). The MEIS is a Managin mirror telescope of aperture size of 95mm, and it images the ground with the ground sampling distance of 13.8m over 48km at the altitude of 720km using three different observations bands. This paper first presents the design and then the optics, relating results of manufacturing, integration and test. Finally it briefly discusses the current status of MEIS operation.

• Journal of the Optical Society of Korea
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• 제5권3호
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• pp.70-75
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• 2001

Next Generation Space Telescope (NGST) is under design study for proposed launch around 2008. It will take over the task of Hubble Space Telescope (HST) and provide much more detailed information about celestial objects. Present large telescopes both in space and on the ground contain aspheric mirrors, called Ritchey-Chretien type. As the size of the telescope becomes larger and the optical quality is requested to be higher, reaching the diffraction limit, more accurate optical testing methods are required. However, there are few testing methods which can achieve the required accuracy for aspheric optics, and none of them has achieved it with certainty. The failure of producing the primary mirror of the Hubble Space Telescope to meet specification is a good example. Moreover, testing aspheric mirrors of large convex form adds the difficulty to extreme. In this paper, space telescopes and large ground-based telescopes are surveyed and testing methods for aspheric optics are reviewed. a method of testing aspheric convex mirrors is suggested.