• Title/Summary/Keyword: stop-hole

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Microfabrication of Submicron-size Hole on the Silicon Substrate using ICP etching

  • Lee, J.W.;Kim, J.W.;Jung, M.Y.;Kim, D.W.;Park, S.S.
    • Proceedings of the Korean Vacuum Society Conference
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    • 1999.07a
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    • pp.79-79
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    • 1999
  • The varous techniques for fabrication of si or metal tip as a field emission electron source have been reported due to great potential capabilities of flat panel display application. In this report, 240nm thermal oxide was initially grown at the p-type (100) (5-25 ohm-cm) 4 inch Si wafer and 310nm Si3N4 thin layer was deposited using low pressure chemical vapor deposition technique(LPCVD). The 2 micron size dot array was photolithographically patterned. The KOH anisotropic etching of the silicon substrate was utilized to provide V-groove formation. After formation of the V-groove shape, dry oxidation at 100$0^{\circ}C$ for 600 minutes was followed. In this procedure, the orientation dependent oxide growth was performed to have a etch-mask for dry etching. The thicknesses of the grown oxides on the (111) surface and on the (100) etch stop surface were found to be ~330nm and ~90nm, respectively. The reactive ion etching by 100 watt, 9 mtorr, 40 sccm Cl2 feed gas using inductively coupled plasma (ICP) system was performed in order to etch ~90nm SiO layer on the bottom of the etch stop and to etch the Si layer on the bottom. The 300 watt RF power was connected to the substrate in order to supply ~(-500)eV. The negative ion energy would enhance the directional anisotropic etching of the Cl2 RIE. After etching, remaining thickness of the oxide on the (111) was measured to be ~130nm by scanning electron microscopy.

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An Experimental Study on the Stress Behavior of Coped Stringers in Steel Railway Bridge - II : Repair · Strengthening Method (철도교 세로보 절취부에서의 응력거동에 관한 실험적 연구 - II : 보수·보강 방법)

  • Li, Guang Ri;Park, Young Suk
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.4A
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    • pp.307-313
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    • 2009
  • In this study, in order to research the repair-strengthening methods, when fatigue crack occurs in the coped stringers of a steel railway bridge, we manufacture the full size of crossbeam-stringer and floor system model. Also the experimental test is performed on the coped stringers applying the repair-strengthening methods using the stop hole, combination plate, connection plate, bracket, and so on. The results indicate that, the most effective method is to set up connection plate and bracket in the top flange and bottom flange of the stringers, while we can consider the method of punching stop holes in the end of the crack as a subsidiary method. It is necessary to set up the combination plate when the length of crack is quite long.

Design and Implementation of Monopole Antenna with Parasitic Element of Spiral Shape and L-Resonator (스파이럴 구조 기생 소자와 L자형 공진기를 갖는 모노폴 안테나 설계 및 구현)

  • Yoon, Kwang-Yeol;Lee, Seungwoo;Kim, Jang-Yeol;Rhee, Seung-Yeop;Kim, Nam
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.1
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    • pp.11-19
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    • 2013
  • In this paper, we designed and implemented the planar monopole antenna using the coupling effect for the multi-band characteristic. A parasitic element for the multi-band characteristic based on a rectangular patch with single resonance is inserted. Spiral shaped parasitic element is used for minimizing the antenna size and obtaining the multi-resonance characteristic. The frequency characteristics are modified and optimized by varying specific parameters. By inserting an L-shaped resonator at both sides of the feed line which connected through the via hole to the ground plane, unnecessary frequency bands are eliminated. Proposed antenna dimension is $40{\times}60{\times}1mm^3$. It is fabricated on the FR-4 substrate(${\varepsilon}_r$=4.4) using a microstrip line of $50{\Omega}$ for impedance matching. By measurement results, the characteristic of the return loss under -10 dB are 1.714~2.496 GHz, 2.977~4.301 GHz, and 4.721~6.315 GHz, and the radiation patterns have omni-directional shapes.

Developing an Early Leakage Detection System for Thermal Power Plant Boiler Tubes by Using Acoustic Emission Technology (음향방출법을 이용한 발전용 보일러 튜브 미세누설 조기 탐지 시스템 개발 및 성능 검증)

  • Lee, Sang Bum;Roh, Seon Man
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.3
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    • pp.181-187
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    • 2016
  • A thermal power plant has a heat exchanger tube to collect and convert the heat generated from the high temperature and pressure steam to energy, but the tubes are arranged in a complex manner. In the event that a leakage occurs in any of these tubes, the high-pressure steam leaks out and may cause the neighboring tubes to rupture. This leakage can finally stop power generation, and hence there is a dire need to establish a suitable technology capable of detecting tube leaks at an early stage even before it occurs. As shown in this paper, by applying acoustic emission (AE) technology in existing boiler tube leak detection equipment (BTLD), we developed a system that detects these leakages early enough and generates an alarm at an early stage to necessitate action; the developed system works better that the existing system used to detect fine leakages. We verified the usability of the system in a 560MW-class thermal power plant boiler by conducting leak tests by simulating leakages from a variety of hole sizes (ⵁ2, ⵁ5, ⵁ10 mm). Results show that while the existing fine leakage detection system does not detect fine leakages of ⵁ2 mm and ⵁ5 mm, the newly developed system could detect leakages early enough and generate an alarm at an early stage, and it is possible to increase the signal to more than 18 dB.

A Study on the Thermal Behaviors of Disk Brake and Pad by Friction Heat (디스크 브레이크와 패드의 마찰열에 의한 열적거동에 관한 연구)

  • Han, Seung-chul
    • Journal of the Korea Convergence Society
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    • v.10 no.12
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    • pp.287-292
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    • 2019
  • This paper analyzes the thermal behaviors of genuine discs used in automobiles and discs coming out of tuning products through FEM analysis. Modeling with genuine disk modeling and tuning disks Model-1, Model-2, Model-3 and analyzing the disk rotation speed was set to 1000rpm. When the brake is operated, the thermal behavior of the disk surface, such as the operating temperature caused by the disk and pad contact, the friction surface temperature after the disk stop, and the thermal deformation, were analyzed. When the brake was activated (0-4.5 seconds), the tuning disk showed 34℃ higher than the original disk, and after the disk stopped (40.5 seconds), the tuning disk was analyzed 18℃ lowe, deformation due to the disk heat was deformed by 0.3mm for the tuning disk. Although there is an effect to reduce the fading phenomenon due to the thermal behavior of the pure disk and the tuning disk, it can be observed that there is no significant change in the thermal behavior due to the hole processing and the disk surface processing of the tuning disk.

Effect of extraction socket granulation tissue graft on the regeneration of horizontal furcation defect (발치와의 육아조직 이식이 치근이개 결손부의 재생에 미치는 영향)

  • Oh, Mok-Hoon;Han, Soo-Boo;Son, Sung-Heui;Yang, Seung-Min;Ko, Jae-Seung
    • Journal of Periodontal and Implant Science
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    • v.26 no.3
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    • pp.735-751
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    • 1996
  • An ultimate goal of periodontal therapy is to stop the disease process and to regenerate a functionally-oriented periodontium destroyed as a result of periodontal disease. The purpose of this study was to observe the effect of grafting granulation tissue obtained from extraction socket on the regeneration of horizontal furcation defect. Six dogs were used in this study. All mandibular first and third premolars were extracted. At 2, 3, and 5 days after extraction, tissues were obtained from extraction socket of 1 mongrel dog and examined by light microscope. Granulation tissue obtained at 5 days after extraction was chosen as the graft material. Five days later, horizontal furcation defects were created surgically at mandibular second and fourth premolars in the right and left side of the 5 beagle dogs. The entrance area of the artificially prepared "key hole" defects were about $3\;4mm^2$. By random selections, 2 exposed furcation defects were grafted with granulation tissue obtained from extraction socket as experimental group and 1 furcation defect was as control. The flaps were replaced to their original position and sutured with 4-0 chromic cat-gut. Three dogs were sacrificed 4 weeks and two dogs 8 weeks after surgery, and the prepared specimens were examined by light microscope. At 4 weeks, furcations were filled with epithelial lining and fibrous connective tissue infiltrated with chronic inflammatory cells. New bone formation was observed in all groups. Only experimental group showed new cementum formation. At 8 weeks, new cementum, functional arrangement of new PDL fiber, root resorption, and some ankylotic union of newly formed alveolar bone and root surface were observed in all groups. Experimental group showed that epithelial downgrowth was inhibited and new bone formation was more active compared to control. The success rate of the furcation defect healing was higher in experimental group than control. These results suggested that grafting of granulation tissue obtained from extraction socket which combined with reconstructive periodontal flap surgery may promote periodontal regeneration of horizontal furcation defect.

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Observation, Experiment, and Analysis of the Ice Spikes Formation (솟는 고드름의 형성과정에 관한 관찰, 실험 및 분석)

  • Yoon, Ma-Byong;Kim, Hee-Soo;Son, Jeong-Ho;Yang, Jeong-Woo
    • Journal of the Korean earth science society
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    • v.30 no.4
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    • pp.454-463
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    • 2009
  • In this study, from January 2006 to February 2009, we observed 107 ice spikes formed in a natural state, and analyzed their environment. We developed an experimental device to reproduce ice spikes in laboratory and successfully made 531 ice spikes. We analyzed the process of the formation and the principle of how those ice spikes grow through videotaped data of the formation in the experiment. In the natural world, when the surface of water and the lower part of a vessel begin to freeze, a vent (breathing hole) develops at the surface where an ice is not frozen; this vent serves as the seed of an ice spike. It is assumed that the volume expansion of ice in the vessel which occurs when water freezes makes the supercooled water go upward through the vent and becomes an ice bar called an ice spike. In the laboratory, however, when distilled water is poured into an ice tray cube and kept in the experimental device for about one and a half hours at a temperature of -12- $-13^{\circ}C$, a thin layer of ice then begins to develop on the surface of the water, the vent is formed, and ice spikes form for about 10-30 minutes. These spikes stop growing when the end becomes clogged. Ice spikes can be described as falling into seven categories of shape, with the apex type topping the list followed by the slant type in the natural state and the vertical type predominating in the laboratory.