• Title/Summary/Keyword: Ring beam

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The Stability of the Flexible Rotor Mounted on Circumferentially Grooved Floating Ring Journal Bearings (원주방향 급유홈 프로팅링 저널베어링으로 지지된 탄성 회전체의 안정성)

  • 정연민;김경웅
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.12
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    • pp.2205-2215
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    • 1992
  • The stability of the flexible rotor mounted on circumferentially grooved floating ring journal bearings was investigated theoretically and experimentally. The floating ring journal bearing was analyzed by using JFO reformation boundary condition. The flexible shaft was analyzed by the finite element method based on Rayleigh beam theory. It was found that the measured ring speed agrees well with the theoretical results. The instability of the system due to not only the outer film but also the inner film of the bearing could be predicted by the theory which allows negative vapor pressure. The tendency that reducing the supply pressure of lubricant stabilizes the system was observed both experimentally and theoretically.

A Study on the Ring Effects of Composite Laminated Conical Shells (복합적층 원뿔형 쉘의 링 보강효과 연구)

  • Park, Weon-Tae;Choi, Jae-Jin;Son, Byung-Jik
    • Journal of the Korean Society of Safety
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    • v.19 no.1
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    • pp.94-101
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    • 2004
  • In this study, composite laminated conical shells with ring stiffeners are analyzed. A versatile 4-node shell element which is useful for the analysis of conical shell structures is used. An improved flat shell element is established by the combined use of the addition of non-conforming displacement modes and the substitute shear strain fields. The proposed element has six degrees of freedom per node and permits an easy connection to other types(beam element) of Optimum location and optimum section properties of ring stiffeners are obtained. It is shown that the thickness of conical shell is reduced about 20% by optimum ring stiffeners.

Design of a Dual-mode Annular Ring Antenna with a Coupling Feed (커플링 급전을 이용한 이중 모드 Annular Ring 안테나 설계)

  • Kim, Jae-Hee;Woo, Dae-Woong;Park, Wee-Sang
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.4
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    • pp.351-356
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    • 2009
  • A dual-mode annular ring antenna for both global positioning system(GPS) and satellite digital multimedia broad-casting(DMB) is designed. The proposed antenna consists of a coupling feed line and four slots on the annular ring patch. The gap between the feed line and the annular ring patch is used for an input impedance matching, and the slot length is used for adjusting the resonant frequency of the $TM_{21}$ mode at the DMB frequency. The antenna was fabricated and measured. The experimental results show that the antenna resonants at the GPS and DMB frequencies with suitable bandwidths, and had a broadside radiation pattern at the GPS band and a conical beam radiation pattern at the DMB band.

A study on the GEO Satellite Tank Support Beam Form Definition at Preliminary Design (초기설계단계의 정지궤도위성 연료탱크 지지대 형상결정에 대한 연구)

  • Choi, Jung-Su;Kim, In-Gul;Kim, Sung-Hoon;Park, Jong-Seok;Kim, Chang-Ho;Yang, Gun-Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.2
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    • pp.157-164
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    • 2007
  • Launch Interface Ring roles as connection department of satellite and launcher for to deliver all structure loads that occur from the satellite, and one of the most intensive load received parts. Especially COMS, the first Korean developing GEO satellite, needs Launch Interface Ring with Tank Support Beam because of dissymmetry fuel tanks. The purpose of this study is the suitable form decision of Launch Interface Ring at preliminary design of COMS. In this study, launch mass and design constraints are investigated. Moreover, optimization algorithm and simplification technique are used. At the beginning of this study, three types of launch interface ring were presented and finally model 3 was the lightest design for resistance of launch environment. Nevertheless, model 1 can be suggested for application to COMS because of the satellite gravity center control and ease of fabrication.

Synthesis and Fragmentation of Furoxanaldehydes in the Gas Phase for Nanopatterned Alkyne Formation on a Solid Surface

  • Kim, Gi-Young;Kim, Ju-Cheon;Lee, Seung-Hee;Kim, Hyung-Jin;Hwang, Kwang-Jin
    • Bulletin of the Korean Chemical Society
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    • v.30 no.2
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    • pp.459-463
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    • 2009
  • Furoxanaldehydes possessing phenyl or alkenyl groups at the 3- or 4-position of the furoxan ring were designed for alkyne formation on a solid surface. Furoxans 2 and 3 were prepared from the corresponding alkenes 2a and 3a by the reaction with NaN$O_2$ in acetic acid. Furoxan 4, in which the furoxan ring is conjugated with a double bond, was prepared from bis(bromomethyl)benzene 4a in 5 steps using the Wittig reaction of aldehyde 1 as the key step. The electron beam-mediated fragmentation of furoxanaldehydes 1-4 in a mass spectrometer was exploited by focusing on alkyne formation on the solid surface. The fragmentation of furoxan 3 possessing diaryl groups afforded diarylacetylene at high efficiency, suggesting that the aryl group conjugated with the furoxan ring could facilitate alkyne formation with the evolution of NO.

Magnetic Measurement of PLS Storage Ring Prototype Dipole Magnet (방사광 가속기용 2극 전자석 특성측정 및 보정)

  • 강봉구;박기현;윤종렬;구양모
    • Journal of the Korean Magnetics Society
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    • v.2 no.2
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    • pp.163-168
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    • 1992
  • Results of magnetic measurement of a prototype Storage Ring dipole magnet for the Pohang Light Source (PLS) are summarized. Hall probe mapping and rotating coil methods are used to measure field profiles and integrated field properties. End chamfering experiments are performed on the as-built magnet, which has four removable pole-end pieces, to meet the specifications set from beam dy-namics requirement. The corrected magnet has efficiency of 99.7% at 2.0 GeV excitation ad higher order multipole error levels less than the specifications for all excitations, showing that the magnet has appropriate properties for the PLS Storage Ring.

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Design and Development of an Ultralow Optical Loss Mirror Coating for Zerodur Substrate

  • Cho, Hyun-Ju;Lee, Jae-Cheul;Lee, Sang-Hyun
    • Journal of the Optical Society of Korea
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    • v.16 no.1
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    • pp.80-84
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    • 2012
  • A high reflectance mirror, which has very low absorption and scattering loss, was coated onto a crystalline substrate by ion beam sputtering and then annealed at $450^{\circ}C$. We carefully selected the mirror coating material, and designed the high reflectance mirror, in order to avoid UV degradation which comes from the He-Ne plasma. We measured the surface roughness of the Zerodur substrate using phase shift interferometry and atomic force microscopy, and compared it with the TIS scattering of the mirror. The cavity ring-down method was used to measure the absorption of the mirror, and the thin film structure was correlated to its results. We also compared the optical properties of coated mirrors before and after annealing.

Finite Element Analysis of P/M Connecting Rod Forging (분말컨넥팅로드 단조의 유한 요소 해석)

  • Park, Jong-Jin
    • Transactions of Materials Processing
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    • v.1 no.1
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    • pp.33-41
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    • 1992
  • Sintered P/M connecting rod is forged to increase density and to satisfy dimensional specifications. Flow of the materials is different form that of wrought materials due to pores in the preform. The Mises yield function was modified to. include the first invariant of stress tensor, and the associated flow rule was derived by applying the normality rule to the yield function. Axisymmetric and plane-strain finite element analyes were carried out for the ring and beam portions of the connecting rod, respectively. The flow of the preform and density change of the analysis are presented in this paper. A load-stroke curve was also presented by superimposing analysis results for the ring and beam portions.

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Experimental Verification of Transverse Electric Mode Controlled Vacuum Chamber of PLS-II Storage Ring

  • Ju, Yeong-Do;Ha, Tae-Gyun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.229-229
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    • 2012
  • It is significant issue to control the unwanted transverse electric (TE) modes in the vacuum chamber for preventing the position reading noise from the beam position monitor (BPM) of storage ring. We introduce shunt structure to control the frequency distribution of TE resonance modes excited in the vacuum chambers of the Pohang Light Source II (PLS-II). The design of shunt structure is performed using the full three dimensional finite-difference time-domain (FDTD) simulation. It is verified that the sympton of the BPM noise is not oberved up to the beam current of 190 mA in the commmissioning of PLS-II.

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Laser Hardening of Piston Ring Groove (피스톤 링그루브의 레이저 열처리)

  • Song, Y.K.;Suh, S.
    • Journal of the Korean Society for Heat Treatment
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    • v.10 no.3
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    • pp.165-171
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    • 1997
  • Laser hardening for the piston ring groove of ductile cast iron was tried. Mechanical and microstructural investigation for the hardened area indicated that the laser heating technique could replace conventional induction hardening process completely and further showed that post grinding process would be eliminated by minimizing bulging of heat treated area. In laser hardening, the volume increase caused by martensitic phase transformation proved to be less than $10{\mu}m$, which insures no post machining on the hardened surface. As expected, the depth of hardening was inversely proportional to the beam scanning velocity and the highest surface hardness was obtained at the beam velocity of 0.75m/min. Heat treatment using phosphate coating demonstrated quite comparable result to the case of graphite suscepter.

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