• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.279-282
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• 2020

In this study, body pressure was quantitatively detected using built-in optical sensors, inside an air cushion seat. The proposed system visualizes the effect of the body pressure distribution on the air cushion seat. The built-in sensor is based on the time-of-flight (ToF) optical method, instead of the conventional electrical sensor. A ToF optical sensors is attached to the bottom surface of the air-filled cells in the air cushion. Therefore, ToF sensors are durable, as they do not come in physical contact with the body even after repeated use. A ToF sensor indirectly expresses the body pressure by measuring the change in the height of the air-filled cell, after being subjected to the weight of the body. An array of such sensors can measure the body pressure distribution when the user sits on the air cushion seat. We implemented a prototype of the air cushion seat equipped with 7 ToF optical sensors and investigated its characteristics. In this experiment, the ToF optical pressure sensor successfully identified the pressure distribution corresponding to a sitting position. The data were accessed through a mobile device.

• Transactions on Electrical and Electronic Materials
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• v.2 no.1
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• pp.22-26
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• 2001

ITO (Indium-tin-oxide) thin films were deposited on glass substrates by a dc magnetron sputtering system using ITO powder target. The methods of heat treatment are important factor to obtain high quality ITO films with low electrical resistivity and good optical transmittance. Therefore, both methods of the substrate temperature and post-deposition annealing temperature have been compared on the film structural, electrical and optical properties. A preferred orientations shifts from (411) to (222) peak at annealing temperature of 200$\^{C}$. Minimum resistivity of ITO film is approximately 8.7$\times$10$\^$-4/ Ωcm at substrate temperature of 450$\^{C}$. Optical transmittances at post annealing temperature above 200$\^{C}$ are 90%. As a result, the minimum value of annealing temperature that is required for the recrystallization of as-deposited ITo thin films is 200$\^{C}$.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1247-1250
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• 2008

This presentation highlights work from the authors' laboratories on the various kinds of oxide optical materials, mainly luminescence and pigment materials with different forms (powder, core-shell structures, thin film and patterning) prepared by the Pechini-type sol-gel (PSG) process. The PSG process which uses the common metal salts (nitrates, acetates, chlorides etc) as precursors and citric acid (CA) as chelating ligands of metal ions and polyhydroxy alcohol (such as ethylene glycol or poly ethylene glycol) as cross-linking agent to form a polymeric resin on molecular level, allowing the preparation of many forms of luminescent materials.

• Journal of the Optical Society of Korea
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• v.8 no.3
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• pp.127-131
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• 2004

This paper investigates applications of femtosecond lasers for the micromachining of transparent materials and fabrication of optical devices. We show commercial micromachining examples of transparent materials which have been fabricated for various applications. Near infrared femtosecond laser processing is an attractive method to fabricate three-dimensional optical waveguides into various transparent materials. Focused femtosecond laser pulses induce a permanent refractive-index change only near the focal point. We also demonstrate a Y coupler with the splitting ratio of 1:1 written by femtosecond laser pulses into a fused silica glass. The minimum propagation loss of 0.8 ㏈/㎝ awl the refractive-index change of 0.006-0.01 at the wavelength of 1550 ㎚ were achieved by optimization of the laser fluence.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.165-165
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• 2006

We prepared nonlinear optical (NLO) polymers possessing thermal and temporal stability, which were based on the polyimides appended with NLO chromophores. NLO chromophores with a terminal hydroxyl group have been synthesized by coupling between aminobenzene or julolidine donor and phenylene bridge, and then subsequent coupling between the resulting product and tricyanofuran acceptor. The chromophores were chemically bonded to the polyimides backbone through Mitsunobu reaction. The NLO polymers showed $160-170^{\circ}C$ of Tgs and were thermally stable up to $200^{\circ}C$. We obtained optical quality films by spincoating and evaluated their electro-optical properties and temporal stability.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.254-258
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• 2002

To realize channel cross-connecting in optical communications systems, a high speed optical matrix switch was fabricated using z-cut $LiNbO_3$. For switch fabrication was design bending structure and coupling length and four $2{\times}2$ directional couplers were integrated on one substrate far construction of a $4{\times}4$ switch. Single-mode optical waveguides were formed by Ti-diffusion at a wet $O_2$ atmosphere. Ti-diffusion profile, refractive index variation and waveguide morphology were analyzed by Prism coupler and optical microscopy, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.901-904
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• 2002

Display performance of mobile LCDs has been improved according to broadening of their application. But there are many demands from market, such as contrast improvement (high color reproducibility), higher efficiency of light usage, thickness reduction, widening its viewing angle and so on. To respond them we have been developing many new types of films. In this paper we introduce new high contrast white polarizers for better color reproducibility, and new film construction for higher light efficiency.

• Laser Solutions
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• v.4 no.2
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• pp.29-38
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• 2001

A development of in-process and reliable monitoring system in laser materials processing is essential for successful applications toward the real industrial fields. It was known that optical signals induced by laser-matter interactions provide a good indication not only to monitor various defects but also to characterize and identify the process However there are still difficulties to implement the optical monitoring system in real fields since the system is susceptible to the spurious change of the signal affected by the variation of experimental conditions and environmental noises. In this article. a new type of optical monitoring technique named 'chromatic modulation technique' is described as a reliable, robust and sensitive monitor for the applications in laser materials processing in order to tackle the conventional problems in optical system.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1148-1151
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• 2009

A self-designed, written in labview, Organic Light-Emitting Diode junction temperature measuring program was used to calculate the internal junction temperature for devices during operation, and an infrared thermometer was used to measure the backside temperature of the device substrate, to discuss the effects of the junction and substrate temperature difference to the characteristics of the device.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1259-1261
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• 1993

Amorphous chalcogenide glasses are highly transparent in the near $1{\mu}m$ wavelength region, which corresponds to the wavelength region of the optical communication system. Optical properties of these materials, including the transmittance, the optical gap, and the shift associated with reversible photostruction change, were measured. Thereafter, optical waveguide was fabricated by the laser lithographic technique and then, guide modes were measured by utilizing the end-fire coupling technique. The field patterns of both the single mode and the multimode waveguide were observed.