• Title/Summary/Keyword: Light Uniformity

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A Novel Photonic Crystal Fiber Sensor with Three D-shaped Holes Based on Surface Plasmon Resonance

  • Bing, Pibin;Sui, Jialei;Huang, Shichao;Guo, Xinyue;Li, Zhongyang;Tan, Lian;Yao, Jianquan
    • Current Optics and Photonics
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    • v.3 no.6
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    • pp.541-547
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    • 2019
  • A novel photonic crystal fiber (PCF) sensor with three D-shaped holes based on surface plasmon resonance (SPR) is analyzed in this paper. Three D-shaped holes are filled with the analyte, and the gold film is deposited on the side of three planes. The design of D-shaped holes with outward expansion can effectively solve the uniformity problem of metallized nano-coating, it is beneficial to the filling of the analyte and is convenient for real-time measurement of the analyte. Compared with the hexagonal lattice structure, the triangular arrangement of the clad air holes can significantly reduce the transmission loss of light and improve the sensitivity of the sensor. The influences of the air hole diameter, the distance between D-shaped holes and core, and the counterclockwise rotation angle of D-shaped holes on sensing performance are studied. The simulation results show that the wavelength sensitivity of the designed sensor can be as high as 10100 nm/RIU and the resolution can reach 9.9 × 10-6 RIU.

Design of a Bar-type TIR Lens Having a Freeform Surface for Forming a Line Beam Using an LED Light Source (LED 광원 사용 시 line beam 형성을 위한 자유 곡면 bar type의 TIR lens 설계)

  • Seo, Jin-Hee;Lee, Jeong-Su;Kim, Seo-Young;Jeong, You-Jin;Park, Hye-Jin;Nam, Deuk-Young;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
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    • v.28 no.6
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    • pp.295-303
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    • 2017
  • In this paper, we have studied a method of forming a line beam using a UV LED. The existing linear-type UV LED curing optical system is composed of several cylindrical lenses, but problems such as optical system alignment, enlargement of the module, efficiency, etc. may arise in the future. As an alternative to these problems, a bar-type TIR lens having a freeform surface only in the y-axis direction is designed, to verify that it shows advantages in maximum illuminance, uniformity of illuminance, and flux efficiency.

Studies on the Production of Roughages from Hyun-aspen(Populus Alba × P. Glandulosa) by Steaming-Defibration and Steaming-Explosion (열해섬(熱解纖) 및 폭쇄처리에 의한 현사시 나무의 조사료화(粗飼料化) 연구(硏究))

  • Kang, Chin-Ha;Paik, Ki-Hyon
    • Journal of the Korean Wood Science and Technology
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    • v.17 no.4
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    • pp.57-69
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    • 1989
  • Roughage feeds were produced from Hyun-aspen (Populus alba $\times$ p. glandulosa) by steaming-defibration and steaming-explosion. The objectives of this work were to find proper conditions for the treatment of Hyun-aspen by analyzing the compositional change and digestibility and to investigate the change of physical properties of exploded woods. The results of this work were as follows; 1. The method of steaming-de fibration gave the best producing rate of feedstuffs when the chips were steamed (9kg/$cm^2$ under the pressure) for 10 minutes. The yield and the digestibility of feedstuffs were 84.2% and 38.1%, respectively. It is the merit of this method that feedstuffs manufactured by this method was uniformity in particle size, and facilities of fiberboard factory could be used directly, 2. For defibration of the chip by explosion, the proper condition was steamed under the pressure (20kg/$cm^2$) for 4 minutes. The yield and the digestibility of feedstuffs were 93.4% and 68.1%, respectively. The feedstuffs produced under these conditions had higher nutritional quality than rice straw and this method was considered as the best for making feedstuffs from Hyun-aspen chip. But it is defect that exploded feedstuffs was ununiformity in particle size and had unique odor. The physical properties of the feedstuffs were investigated by a light microscope and a TEM. The feedstuffs produced under the low pressure (20 kg/$cm^2$) still maintained the structure of fibers. However, the feedstuffs produced under the high pressure (28 kg/$cm^2$) resulted in higher de fib ration than these prepared under the low pressure. The highly defibrated feedstuffs recombined with solublized lignin. The crystallinity of feedstuffs was increased by 10% and micelle width increased double after treatment.

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The Study of Optical Device embedded Optical Alignment fabricated by Roll to Roll Process (롤투롤 공정을 이용한 광정렬 구조 내장형 광소자 연구)

  • Jo, Sang-Uk;Kang, Ho-Ju;Jeong, Myung-Yung
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.3
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    • pp.19-22
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    • 2013
  • Recently, high speed transmission and large information demand have been increased. Also, researches of integrated optical device for large production and high-efficient planar lightwave circuit (PLC) have been increased. In this paper, integrated optical alignment is proposed which makes passive alignment between optical device and optical fiber possible. The integrated optical device consists of splitter structures which have one input and two outputs. The proposed integrated structure was fabricated by roll-to-roll (RTR) processing method. This method enables to manufacture continuously and the processing time can be shortened. Optical property of the fabricated optical device showed 3.9 dB insertion loss and 0.2 dB optical uniformity using the light source with 1550 nm wavelength.

Application of Ceramic Aggregate for Ultra-High Strength Concrete (초고강도 콘크리트 제조를 위한 세라믹골재 개발)

  • Kim, Song-Ho;Kang, Suk-Hwa;Song, Yong-Soon;Kim, Kang-Min
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.389-392
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    • 2008
  • Ultra-high strength concrete becomes one of the main research areas because recently concrete structure is larger. The quality of aggregate (ultra-high strength and uniformity) as well as chemical admixture and mineral additives is a key factor for ultra-high strength concrete development. However, natural aggregate including crushed aggregate is inappropriate for ultra-high strength concrete because ultra-high strength quality cannot be maintained uniformly over whole natural aggregate lot. In this study ceramic aggregate was applied for ultra-high strength concrete in order to assure uniform quality of ultra-high strength aggregate. Ultra-high strength concrete was achieved by applying coated ultra-high strength ceramic aggregate to enhance the bonding strength between aggregate and cement paste. Also for actual application light weight ceramic aggregate(density 2.2 $g/cm^3$) with zero water absorption was tested.

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High Efficiency AMOLED using Hybrid of Small Molecule and Polymer Materials Patterned by Laser Transfer

  • Chin, Byung-Doo;Suh, Min-Chul;Kim, Mu-Hyun;Kang, Tae-Min;Yang, Nam-Choul;Song, Myung-Won;Lee, Seong-Taek;Kwon, Jang-Hyuk;Chung, Ho-Kyoon;Wolk, Martin B.;Bellmann, Erika;Baetzold, John P.
    • Journal of Information Display
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    • v.4 no.3
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    • pp.1-5
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    • 2003
  • Laser-Induced Thermal Imaging (LITI) is a laser addressed patterning process and has unique advantages such as high-resolution patterning with over all position accuracy of the imaged stripes of within 2.5 micrometer and scalability to large-size mother glass. This accuracy is accomplished by real-time error correction and a high-resolution stage control system that includes laser interferometers. Here the new concept of hybrid system that complement the merits of small molecule and polymer to be used as an OLED; our system can realize easy processing of light emitting polymers and high luminance efficiency of small molecules. LITI process enables the stripes to be patlerned with excellent thickness uniformity and multi-stacking of various functional layers without having to use any type of fine metal shadow mask. In this study, we report a full-color hybrid OLED using the multi-layered structure consisting of small molecules and polymers.

Properties of ZrO2 Gas Barrier Film using Facing Target Sputtering System with Low Temperature Deposition Process for Flexible Displays (플렉서블 디스플레이용 저온공정을 갖는 대향 타겟식 스퍼터링 장치를 이용한 ZrO2 가스 차단막의 특성)

  • Kim, Ji-Hwan;Cho, Do-Hyun;Sohn, Sun-Young;Kim, Hwa-Min;Kim, Jong-Jae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.5
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    • pp.425-430
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    • 2009
  • $ZrO_2$ film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets ($d_{TT}$), the distance between the target and the substrate ($d_{TS}$), and the deposition time. The $ZrO_2$ film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the $ZrO_2$ film with optimized condition ($d_{TT}$=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the $ZrO_2$ film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.

The Stress Distribution Analysis of PEMFC GDL using FEM (유한요소법을 이용한 고분자전해질연료전지 기체확산층의 응력분포 연구)

  • Kim, Chulhyun;Sohn, Youngjun;Park, Gugon;Kim, Minjin;Lee, Jonguk;Kim, Changsoo;Choi, Yusong;Cho, Sungbaek
    • Journal of Hydrogen and New Energy
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    • v.23 no.5
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    • pp.468-475
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    • 2012
  • A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

Analysis of the Output Characteristics of IGZO TFT with Double Gate Structure (더블 게이트 구조 적용에 따른 IGZO TFT 특성 분석)

  • Kim, Ji Won;Park, Kee Chan;Kim, Yong Sang;Jeon, Jae Hong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.4
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    • pp.281-285
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    • 2020
  • Oxide semiconductor devices have become increasingly important because of their high mobility and good uniformity. The channel length of oxide semiconductor thin film transistors (TFTs) also shrinks as the display resolution increases. It is well known that reducing the channel length of a TFT is detrimental to the current saturation because of drain-induced barrier lowering, as well as the movement of the pinch-off point. In an organic light-emitting diode (OLED), the lack of current saturation in the driving TFT creates a major problem in the control of OLED current. To obtain improved current saturation in short channels, we fabricated indium gallium zinc oxide (IGZO) TFTs with single gate and double gate structures, and evaluated the electrical characteristics of both devices. For the double gate structure, we connected the bottom gate electrode to the source electrode, so that the electric potential of the bottom gate was fixed to that of the source. We denote the double gate structure with the bottom gate fixed at the source potential as the BGFP (bottom gate with fixed potential) structure. For the BGFP TFT, the current saturation, as determined by the output characteristics, is better than that of the conventional single gate TFT. This is because the change in the source side potential barrier by the drain field has been suppressed.

Sensitivity improvement of $CeO_2$ oxygen sensor by betterment of surface characteristics through chemical mechanical polishing process (CMP 공정을 통한 표면 특성 개선에 의한 $CeO_2$ 산소 센서 감도 향상 연구)

  • Jung, Pan-Gum;Jun, Young-Kil;Ko, Pil-Ju;Kim, Nam-Hoon;Lee, Woo-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.65-65
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    • 2007
  • Microstructure and surface roughness of the sensing materials should be improved to use them in advanced sensor applications because the uneven surface roughness degrades the light reflection, pattern resolution, and devices performance. Chemical mechanical polishing (CMP) processing was selected for improving the surface roughness of $CeO_2$ which is one of the well known materials for the oxygen gas sensors. Surface roughness and removal rate of spin coated $CeO_2$ thin films were examined with a change of CMP process parameters such as down force and table speed. The optimized process condition, reflected by the surface roughness with the hillock-free surface as well as the excellent removal rate with the good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of $CeO_2$ thin films were also confirmed. The improved sensitivity of $CeO_2$ thin films for oxygen sensors were obtained after CMP process by the improved surface characteristics. Therefore, we conclude that sensing property of $CeO_2$ thin film is strongly dependent on the surface roughness of $CeO_2$ thin films by using CMP process.

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