• Title/Summary/Keyword: Thin-Wall

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An Improved Pipe Hoop Stress Formula

  • Lee, Jaeyoung
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.76-82
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    • 2001
  • The ASME B3l.4〔1〕and B3l.8 〔2〕codes use the thin wall formula to predict hoop stress in a pipe. To account for the external pressure, the above codes simply subtract the external pressure from the internal pressure. The thin wall formula using this differential pressure does not give the same hoop stress as the thick wall formula. This paper proposes an improved equation to predict pipe hoop stress subjected to both internal and external pressure. Compared to the conventional thin wall formula, the improved formula has additional terms, which improve the agreement with the thick wall formula and account for external pressure. The improved formula is less conservative than the conventional thin wall formula, but slightly more conservative than the thick wall formula. The formula is simpler and easier to use than the thick wall formula and will save pipe material cost as well as installation cost compared to using the conventional thin wall formula. The savings will increase as the water depth increases.

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Deposition of Tungsten Thin Film on Silicon Surface by Low Pressure Chemical Vapor Deposition Method (저압 화학 기상 증착법을 이용한 실리콘 표면 위의 텅스텐 박막의 증착)

  • Kim, Seong Hun
    • Journal of the Korean Chemical Society
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    • v.38 no.7
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    • pp.473-479
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    • 1994
  • Tungsten thin film was deposited on p-(100) silicon substrate by using the LPCVD(low pressure chemical vapor deposition) technique. $WF_6$ was used as a source gas for tungsten and $SiH_4$ was used as a reducing gas for $WF_6$. Tungsten thin film was deposited by either SiH4 or Si substrate reduction of $WF_6$ under cold-wall condition and it was deposited by $SiH_4$ reduction of $WF_6$ under hot-wall condition. The crystal structure of deposited thin film under both conditions were identified to be bcc (body centered cubic). The physical and electrical properties of deposited thin films were investigated. The deposited film under hot-wall condition changed to $WSi_2$ film by the annealing under $800^{\circ}C.$ From the experimental results and theoretical considerations, the change of the crystal structure of the thin film by annealing was discussed. $WSi_2$ thin film, which was known to have good compatibility with Si substrate, could be produced under hot-wall condition although the film properties were superior under cold-wall condition.

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Reinforcing Effect of Thin-wall at Serviceability Condition (상시하중상태에서 박벽의 보강효과에 대한 연구)

  • Kim, Doo-Hwan;Yoon, Seong-Soo;Park, Jin-Seon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.2
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    • pp.11-17
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    • 2010
  • For the reasonable analysis of design problems for agricultural facilities, considered the reinforcing effect of thin-wall. The most of agricultural structure is constructed small scale and have many purposes. Thus it has been designed temporary rather than permanent structure, and has relatively large slenderness ratio, small section and semi-rigid condition. Therefore many agricultural facilities are consist of relatively strong frame with weak wall at the viewpoint of stiffness and have not been reflected in the design. But the tension field influences to collapse of structure have already known. Therefore, we need quantification the effect of tension field at structural analysis. In this study, present the method of quantification the effect of tension field that came out thin-plate surrounded by high stiffness frame. The numerical results show that the effect of tension field effect for thin-wall is about 5% of the sectional area of frame in study agricultural facilities.

A Study on Improvement of Flow Characteristics for Thin-Wall Injection Molding by Rapid Mold Heating (급속 금형가열에 의한 박육 사출성형의 유동특성 개선에 관한 연구)

  • Park Keun;Kim Byung H.
    • Transactions of Materials Processing
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    • v.15 no.1
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    • pp.15-20
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    • 2006
  • The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.

Improvement of Flow Characteristics for Thin-Wall Injection Molding by Rapid Beating (급속 가열에 의한 박육 사출성형의 유동특성 개선)

  • Kim, Byung;Park, Keun
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.9-12
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    • 2005
  • The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filing difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation fur both the conventional molding and the RTR molding processes

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Domain Wall Motions in Ferromagnetic Thin Film Induced by Laser Heating Pulse

  • Park, Hyun Soon
    • Applied Microscopy
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    • v.48 no.4
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    • pp.128-129
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    • 2018
  • Soft ferromagnetic materials are utilized for various electromagnetic devices such as magnetic recording heads and magnetic shielding. In situ observation of magnetic microstructures and domain wall motions are prerequisite for understanding and improving their magnetic properties. In this work, by the Fresnel (out-of-focus) method of Lorentz microscopy, we observe the domain wall motions of polycrystalline Ni/Ti thin film layers triggered by single-shot laser pulse. Random motions of domain walls were visualized at every single pulse.

Initial Magnetization and Coercivity Mechanism in Amorphous TbxCo1-x Thin Films with Perpendicular Anisotropy

  • Kim, Tae-Wan;Lee, Ha-Na;Lee, Hyun-Yong;Lee, Kyoung-Il
    • Journal of Magnetics
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    • v.15 no.4
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    • pp.169-172
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    • 2010
  • The coercivity mechanism in permanent magnets was analyzed according to the effects of domain nucleation and domain wall pinning. The coercivity mechanism of a TbCo thin film with high perpendicular magnetic anisotropy was considered in terms of the local inhomogeneity in the thin film. The initial magnetization curves of the TbCo thin films demonstrated domain wall pinning to be the main contributor to the coercivity mechanism than domain nucleation. Based on the coercivity model proposed by Kronmuller et al., the inhomogeneity size acting as a domain wall pinning site was determined. Using the measured values of perpendicular anisotropy constant ($K_u$), saturation magnetization ($M_s$), and coercivity ($H_c$), the inhomogeneity size estimated in a TbCo thin film with high coercivity was approximately 9 nm.

Opto-electric Properties of $ZnIn_2S_4$ single crystal thin film Grown by Hot Wall Epitaxy method (Hot Wall Epitaxy (HWE)에 의한 성장된 $ZnIn_2S_4$ 단결정 박막의 광전류 특성)

  • Hong, Kwang-Joon;Lee, Sang-Youl
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.71-72
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    • 2006
  • The stochiometric mixture of evaporating materials for the $ZnIn_2S_4$ single crystal thin film was prepared from horizontal furnace. To obtain the $ZnIn_2S_4$ single crystal thin film. $ZnIn_2S_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100). In the Hot Wall Epitaxy(HWE) system. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the $ZnIn_2S_4$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0148 eV and 0.1678 eV at $10_{\circ}K$, respectively.

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A Study on the Responsibility of Thin film instantaneous surface temperature probe of a Dual-pipe structure (이중관 구조 박막형 순간온도 프로브의 응답성에 관한 연구)

  • Choi, Seok-Ryeol;Park, Kyoung-Suk
    • 한국연소학회:학술대회논문집
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    • pp.237-242
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    • 2003
  • The measurement study of instantaneous temperature at combustion chamber wall and the temperature of combustion gas has been under lots of research and development to conclude the temperature process in internal combustion engine for combustion characteristics analysis. The measurement with fast responsibility should be used for temperature measurement inside combustion chamber wall since temperature of wall changes, due to the various gas temperature, irregularly during the combustion. Therefore, thin film instantaneous surface temperature probe, which characterizes the fastest and the most accurate responsibility among contact typed temperature measurement, was used for the experiments. This new thin film instantaneous surface temperature probe improved the problems of noise and durability. The optimal coating thickness of thin film instantaneous surface temperature probe was proven to be $10{\mu}m$ for the best responsibility and durability. It also allowed the stable temperature measurement be taken up to $1,200^{\circ}C$ and proven to be read possibly from the combustion chamber wall.

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Characterization of $RuO_2$ Thin Films by Hot-wall Metal Organic Chemical Vapor Deposition (Hot-wall MOCVD에 의한 $RuO_2$ 박막의 특성)

  • 신웅철;윤순길
    • Journal of the Korean Ceramic Society
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    • v.33 no.9
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    • pp.969-976
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    • 1996
  • RuO2 thin films were deposited on SiO2(1000 $\AA$)/Si by hot-wall Metal Organic Chemical Vapor Depositon. The crystallinity of RuO2 thin films increased with increasing deposition temperature and the preferred orienta-tion of RuO2 films converted (200) plane to (101) plane with increasing film thicknesses. Such a change in preferred orientation was influenced on the crystallographic structure and the residual stress of RuO2 thin films. The resistivity of the 2700$\AA$-thick RuO2 thin films deposted at 30$0^{\circ}C$ was 52.7$\mu$$\Omega$-cm and they could be applicable to bottom electrodes of high dielectric materials. However the resistivity of RuO2 thin films increased with decreasing film thicknesses. The grain size and the resistivity of RuO2 thin films were densified with increasing the annealing temperature and showed the decrease of resistivity.

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