• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.526-526
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• 1996

The single crystal of LiTaO3 is well known eletro-optic material as well as the piezoelectric one applied to SAW filter. LiTaO3 has large electro-optic effects, so applied to optical switch, acosto-optic deflector, and optical memory device using photorefractive effects. The crystal growth of SAW-grade LiTaO3 has been studied many aspects, but there is no detail research about optic-grade crystal growth. The conditions of optic-grade LiTaO3 single crystal are as below. The optical transmittance must be over 75%, and axial and radial concentratiom uniformity below 1%. The variation of Curie temperature depending on Li/Ta ratio must be also below 2$^{\circ}C$ and no internal no internal cracks and defects. Because of the limitation of crystal quality, the growing of optic-grade LiTaO3 single crystal is very difficult compared with the growing of SAW-grade. In this research, upper conditions of optic-grade single crystal was investigated after growing of 1 inch diameter and 1.5 inch length LiTaO3 single crystal having no internal cracks and defects using Czochralski method. Curie temperature was determined with DSC and measuring capacitance and lattice parameter was calculated about the grown crystal and ceramic powder samples of various Li/Ta ratio. The result of Tc variation was below 1.2$^{\circ}C$ all over the grown crystal, so it is confirmed that LiTaO3 was grown under congruent melting composition having optical homogeniety. Also, the optical transmittance was about 78%, which was sufficient for optical device.

• Korean Journal of Materials Research
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• v.2 no.5
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• pp.366-374
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• 1992

Mechanical and impact properties of stitched S2 glass fiber reinforced polyester woven laminates composites have been studied. Laminates were stitched using Kevlar 49 thread with 1/2, 1, and 2 inch stitch spacing. Tensile and 3-point bending tests haute been performed to evaluate the mechanical properties of stitched and unstitched laminates. Impact tests at applied energy of 234.7J were performed to examine the impact behavior and toughness changes of the specimen. The same specimens were also tested repeatedly at low impact energy level of 110.2J for 3 times to evaluate damage tolerance properties. The tensile and 3-point bending test results showed that one inch spacing specimen had the highest tensile and flexural strength. It also showed the highest energy absorption capability and the best damage tolerance property at the repeated impact test. The half inch spacing specimen showed the lowest tensile strength and energy absorption property at the impact energy level of 234.7J, even though it had the highest frequency of stitching thread.

• Korean journal of applied entomology
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• v.12 no.1
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• pp.41-46
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• 1973

1) The optimum temperature for mass rearing of stable fly was $26^{\circ}C$ centigrade. Number of days required for stage of development at $26^{\circ}C$ were 6.8 days for larval stage, 5.3 days for pupla stage, 10.4 days for preovipositionla stage, and 30 days for adult stage respectively. 3) The pupation rate, emergence rate and sex ratio were $80.7\%,\;84.3\%$ and 1 : 1, respectively. 3) The average weight of pupae was 14.5mg, and the standard medium showed better result in larvae rearing than wheat bran medium. 4) The optimum number of eggs for inoculation on 125gr medium was approximately 310. 5) Optimum size of resting place was determined as $2inch^2/adult$ when it reared in a rectangular cage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.406-417
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• 1997

A numerical study was conducted on the optimum magnetic field intensity and asymmetric factor for uniform axial oxygen concentration in 8 inch silicon single crystal growing process by magnetic Czochralski method. For constant shape of cusp field, a change of coil and crucible position were compared. In case of symmetric cusp field, magnetic field intensity variation shows concave downward with crystal growing for uniform, axial oxygen concentration. A numerical results show similar value of standard deviation of average oxygen concentration for uniform oxygen concentration between coil and crucible position change. In case of asymmetric cusp field. asymmetric factor is increased with crystal growing to have uniform oxygen concentration.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1361-1370
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• 2006

An electronic beam mis-landing phenomenon on the RGB (red/green/blue) -fluorescent surface has been considered as one of serious problems to be solved in cathode-ray tube (CRT), which is generally caused by mechanical shock and vibration. In this work, structural design concepts on the major parts of the CRT, such as a frame, a shadow mask, and a spring, are studied to improve the mechanical shockproof character of a CRT by FEM-analyses and experimental approaches ; a frame is newly designed to have strength employing the double-corner-beads which reduces considerably the distortion of the frame and the shadow mask : the edge-bead of a shadow-mask is redesigned to maintain the wide curved surface of a shadow-mask after mechanical shock : finally, a spring supporting the frame and the shadow-mask is designed to have enough flexibility along drop-direction. As an example, a conventional type of a 15inch CRT was utilized to demonstrate the feasibility and usefulness of this work. Overall, some favorable information on the structural design of the CRT is achieved, and the mechanical shockproof character of a 15-inch CRT is improved in the degree of 3G $(1G=9.81m/s^2)$ as an average-value.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.99-102
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• 2009

The recent LCD TV market has made efforts to produce thinner, brighter, and clearer products, and experienced the rapid light source replacement from a line source of light CCFL to a point source of light LED. In particular, LGP(Light Guiding Panel) among key parts composing BLU(Back Light Unit) has limits of the injection molding technology as well as the mold design, its processing and manufacturing technology so that it is hard to produce large LGP over 40 inch. To produce large light-guide panels over 40 inch under the injection molding process, a mold 3D model was developed in the design process before manufacturing a mold and structure unification was processed through CAE analysis. As a result, it was possible to construct the mold design process, and it is expected to manufacture the optimized mold by applying the mold design and manufacturing process of large-scale rapid injection-compression molding that will be produced in the future.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.733-738
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• 2006

As the film transistor-liquid crystal display (TFTLCD) panels become larger and provide higher resolution, the propagation delay of row and column lines, the voltage modulation of Vcom, and the response time of liquid crystal affect the display images now more than in the past. It is more important to understand the electrical characteristic of TFT-LCD panels these days. This paper describes the electrical model of a 15-inch XGA ($1024{\times}768$) TFT-LCD panel. The parasitic resistance and capacitance of its panel are obtained by 3D simulation of a sub pixel. The accuracy of these data is verified by the measured values in an actual panel [1]. The developed panel simulation platform, the equivalent circuit of a 15-inch XGA panel, is simulated by HSPICE. The results of simulation are compared with those of experiment, according to changing the width of signal. Especially, the proposed simulation platform for modeling TFTLCD panels can be applied to large size LCD TVs. It can help panel and circuit designers to verify their ideas without making actual panels and circuits.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.67.3-68
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• 2018

We plan to automatize the operation of Kyung Hee Astronomical Observatory (KHAO) 76 cm Telescope by adapting KAOS30 (KHU Automatic Observing Software for McDonald 30 inch Telescope). The software is developed to improve the efficiency of the observation system for monitoring transients and variable sources. It has installed and operated at McDonald 30 inch telescope since 2017 August. KAOS76 (KHU Automatic Observing Software for KHAO 76 cm Telescope) consists of four packages: Telescope Control Package (TCP), Data Acquisition Package (DAP), Auto Focus Package (AFP), and Script Mode Package (SMP). Most of the packages can be configured by minimized modifications of the codes because it includes common libraries for FLI instruments and also ASCOM standard. TCP, DAP, and AFP control astronomical devices. SMP supports automatic observing in a script mode. TCP of KAOS76 can communicate with the TCS via ASCOM. Also, KAOS76 has an extra function to compensate the misalignment of the polar axis. In this poster, we show the current status of the observing system with KAOS76.

• Ceramist
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• v.22 no.4
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• pp.452-463
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• 2019

A quartz glass crucible is the essential material for manufacturing silicon ingots such as semiconductors and solar cells. Quartz glass crucibles for semiconductors and solar cells are made similar, but differ in surface purity, structure and durability. Recently, ultra high purity synthetic glass crucibles for semiconductors have become more important due to foreign problems. In Korea, it has succeeded in producing 28-inch quartz glass crucibles through the past 10 years. However, 32-inch synthetic quartz glass for the production of silicon ingots for semiconductors is not up to the level of advanced technology, and the technology gap is expected to be 2 to 3 years. In order to overcome these technological gaps and localize synthetic quartz glass ware, close cooperation between production companies and demand companies and localization of synthetic quartz glass powder must also be made. In addition, if government support can be added, faster results can be expected.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.141-144
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• 2007

We demonstrated 4 inch QVGA AMOLED display driven by GaInZnO TFT. The structure of GaInZnO TFT is back channel etch (BCE) which is conventional structure for a-Si TFT. The electron mobility of GaInZnO TFT is $2.6\;cm^2/Vs$ and Vt is 3.8V. It is thought that GaInZnO TFT could be backplane for AMOLED TV.