• Title/Summary/Keyword: V-angle

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Heat Transfer in a Two Wall Divergent Rectangular Channel with V-Shaped Ribs on One Wall (한 벽면에 V형 리브가 있는 2면 확대 사각채널의 열전달)

  • Lee, Myung-Sung;Ahn, Soo-Whan
    • Journal of Power System Engineering
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    • v.19 no.5
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    • pp.32-37
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    • 2015
  • The present study is to investigates the convective heat transfer characteristics and pressure drop inside the rib-roughened cooling passage of gas turbine blades. The divergent rectangular channel is fabricated with V-shaped ribs on one wall only and the inlet hydraulic diameter to outlet hydraulic diameter ratio($D_{ho}/D_{hi}$) of 1.49 is used. The current investigation has covered a Reynolds number (Re) range of 22,000~75,000, relative roughness height ($e/D_h$) of 0.1~0.2, and rib angle of attack (a) of $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$ for a fixed relative pitch of 10. Results show that the Nusselt numbers are the greatest in the $60^{\circ}$-angled ribs; however, the total friction factors are the highest in the $30^{\circ}$-angled ribs.

A Study on Effects of Fuel Injection System on the Performance in a V8-Type Diesel Engine (V8형 디젤엔진의 성능에 미치는 분사계의 영향에 관한 연구)

  • 박병학
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.2
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    • pp.248-256
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    • 1998
  • The effects of fuel injection system on the performance in a V8-type diesel engine was stuided in this paper. Fuel injection system is important factor which influence the engine performance and exhaust emission bcasuse the properties in the injected fuel depend on the atomization characteristics. In this study using diesel engine of 17.7:1 compression ration the engine performance and exhaust emission are measured experimentally according to 1000, 1400, 2200rpm in the full-load conditions. The chosen parameters for the major system are such diameter shape of combustion chamber and intake system. The results are as follows: As the nozzle hole diameter and injection angle become smaller and as the injection timing gets advanced the fuel consumption and concentration of smoke are decreasing whereas concentration of $NO_{x}$ is increasing. Andconcentration of $NO_{x}$ is increasing in accordance with the increase of injection pipe diameter and nozzle protrusion. Also it is shown that re-entrant type combustion chamber is more effective than that of toroidal type in the improvement of $NO_{x}$ reduction.

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Refilled mask structure for Minimizing Shadowing Effect on EUV Lithography

  • Ahn, Jin-Ho;Shin, Hyun-Duck;Jeong, Chang-Young
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.4
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    • pp.13-18
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    • 2010
  • Extreme ultraviolet (EUV) lithography using 13.5 nm wavelengths is expected to be adopted as a mass production technology for 32 nm half pitch and below. One of the new issues introduced by EUV lithography is the shadowing effect. Mask shadowing is a unique phenomenon caused by using mirror-based mask with an oblique incident angle of light. This results in a horizontal-vertical (H-V) biasing effect and ellipticity in the contact hole pattern. To minimize the shadowing effect, a refilled mask is an available option. The concept of refilled mask structure can be implemented by partial etching into the multilayer and then refilling the trench with an absorber material. The simulations were carried out to confirm the possibility of application of refilled mask in 32 nm line-and-space pattern under the condition of preproduction tool. The effect of sidewall angle in refilled mask is evaluated on image contrast and critical dimension (CD) on the wafer. We also simulated the effect of refilled absorber thickness on aerial image, H-V CD bias, and overlapping process window. Finally, we concluded that the refilled absorber thickness for minimizing shadowing effect should be thinner than etched depth.

Dependence of needle tip Curvature of the Inception Stress and Propagation of electrical tree (침전극의 곡율반경에 따른 트리개시전계 및 트리진전 특성)

  • 박영국;김완수;이홍규;이용희;임기조
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.59-62
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    • 1999
  • Inception and propagation of electrical tree and properties of Partial discharge(PD) pulses accompanying with tree as a function of needle tip radius in low density polyethylene were discussed. To study on these characteristics in different tip radius, we used specimens with needle-plane electrode system made of LDPE, observed inception and propagation of electrical tree by optical microscope with computer and investigated the characteristics of the phase resolved PD pulses accompanying with propagation of electrical tree. The PD quantities detected and analysed were PD magnitude, mean phase angle, average discharge, and the statistical characteristics of the PD pulses. As the tip radius ${\gamma}$ increases, tree inception stress E$\sub$i/ converges to constance value. This result suggests that tree inception stress E$\sub$i/ increases due to stress relaxation when the tip radius is small. Branch-type electrical tree was formed When E$\sub$i/ is 640-750[kV/mm]. bush-type electrical tree when E$\sub$i/ is 370∼400[kV/mm], branch-like electrical tree when E$\sub$i/ is 370-400[kV/mm].

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A STUDY ON THE MARGINAL LEAKAGE OF COMPOSITE RESIN (복합(複合) resin의 변록누출(邊綠漏出)에 관(關)한 실험적(實驗的) 연구(硏究))

  • Cho, Jin-Ho
    • Restorative Dentistry and Endodontics
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    • v.7 no.1
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    • pp.131-138
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    • 1981
  • The purpose of this study was to evaluate the marginal leakage of composite resin. Preparing 144 class V cavities on freshly extracted noncarious teeth, composite resins were prepared and inserted by one dentist according to the manufacturer's instructions. The experiments were performed in two different groups; In group I; Class V cavities with $90^{\circ}$ cavosurface angle, In group II; Class V cavities with $135^{\circ}$ cavosurface angle. And each group was divided 2 subgroups; In control group; composite resin restoraions without acid etch technique. In experimental group; composite resin restorations with acid etch technique. All specimens were immersed in 0.05% crystal violet solution. Before examination, the restored teeth were subjected to thermal stress. The specimens were sectioned occlusogingivally through the center of the restorations with a diamond disk. The sections were examined under a reflected light microscope at 1 day, 7 days and 30 days after immersing the specimens in dye solution. The results were as follows; 1. Control group of group I and group II showed marginal leakage. 2. The degree of marginal leakage in experimental group was greater reduced than control group. 3. In control group, the degree of marginal leakage in group I was greater than group II. 4. In experimental group, there is not statistical differences of the degree of marginal leakage between group I & group II.

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Characterization of V-Insert Clamp Joint Applied to Automobile Exhaust Pipes (차량 배기관용 V-Insert 클램프의 체결 성능 평가)

  • Hwang, Young-Eun;Yoon, Sung-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.2
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    • pp.208-213
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    • 2012
  • In this study, the mechanical joint performance of the V-Insert clamp applied to automobile exhaust pipes was evaluated through the experimental investigation of its axial load capacity. The axial load of the V-Insert clamp was also determined by using theoretical equations presented by Shoghi and compared with the experimental results. As results of the theoretical prediction, the axial load of the V-Insert clamp tended to increase along with smaller angle of the V-Insert segment and the lower friction coefficient between the V-Insert segment and exhaust pipes. The experimental results under tightening effects were similar to the theoretical results and the axial load of the V-Insert clamp presented maximum values in the range of all torques at distance of 2mm between each exhaust pipes. The experimental results under loading effects were similar to the theoretical results in the range of lower torques but deviated from the theoretical results in the range of higher torques. These results would be beneficial to improve the joint and sealing performance of the V-Insert clamp.

Effect of cylinder diameter and boat tail angle on the free vibration characteristics of a typical payload fairing

  • Ramamurti, V.;Rajarajan, S.;Rao, G. Venkateswara
    • Structural Engineering and Mechanics
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    • v.13 no.3
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    • pp.345-353
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    • 2002
  • Three noded plate and shell finite element and 3D beam element in conjunction with Lanczos method are used for studying the effect of boat tail angle on the free vibration characteristics of a typical payload fairing for three different cylinder diameters with height to diameter ratio 1.5. Configurations without boat tail structural member are also studied. One half of the one side fairing structure is considered for the analysis and symmetric boundary conditions are used.

Design of Low Voltage Piezoelectric Actuated Mirror for Micro-CCR (마이크로 CCR구현을 위한 저전압 구동 압전 반사경 설계)

  • Lee, Duk-Hyun;Yang, Chang-Soo;Park, Jae-Y.
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1454-1455
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    • 2008
  • This paper present a piezoelectric actuated mirror with PZT cantilevers, torsional bars and hinges for Micro-CCR (corner cube retroreflector). The actuated mirror with low voltage and large tilting angle is designed and simulated by using FEM (Finite Element Method) simulator (CoventorWare). The tilting angle of actuated mirror is 2.93$^{\circ}$ at low voltage of 5V.

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Improvement of Corrosion Resistance of Aluminum Alloy with Wettability Controlled Porous Oxide films

  • Sakairi, M.;Goyal, V.
    • Corrosion Science and Technology
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    • v.15 no.4
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    • pp.166-170
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    • 2016
  • The combined process of porous type anodizing and desiccation treatment was applied to improve wettability of A1050 aluminum alloy. The water contact angles of anodized samples were increaseds considerably with desiccation treatment. However, there was no considerable effect of polishing and anodizing time on water contact angle. The corrosion behavior with the treatments was investigated electrochemically. The corrosion resistance of the samples in 3.5 mass% NaCl solutions increased with higher contact angle. Anodized and desiccated samples showed better corrosion resistance than un-desiccated samples around rest potential region.

The Comparative analysis of X-ray film on Lumbar Scoliosis and HNP by Barge Method (Barge 방식에 의한 요추부 척추측만증과 추간판 탈출증의 X-ray 비교분석)

  • Kim, Gyu-Sub
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.6 no.1
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    • pp.53-61
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    • 2011
  • Objective: The purpose of this study is to evaluate the disc block subluxation for lumbar scoliosis and herniation of nucleus pulpous (HNP). Methods: We used AP & Lateral view X-ray for patients. And we measured of disc wedge angle, vertebral body rotation to evaluate the typical and atypical disc block subluxation. Results: On the analysis of the lateral view X-ray, 4th lumbar intervertebral disc angle (I.V.D angle) showed $4^{\circ}$, $5^{\circ}$, $3^{\circ}$, $0^{\circ}$ in the cases. On the 4th lumbar analysis of the AP view X-ray, lumbar scoliosis showed right disc wedge angle was $11^{\circ}$ (case 1), $17^{\circ}$ (case 2) and left vertebral body rotation was 13mm, 6mm. Lumbar HNP showed left disc wedge angle was $5^{\circ}$ (case 3), $4^{\circ}$ (case 4) and left vertebral body rotation was 2mm, 4mm. Conclusions: Disc block subluxation has been in lumbar scoliosis, but not been in lumbar HNP.

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