• Title/Summary/Keyword: 회전 강도

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In-plane Stress Analysis of Relating Composite Disks (복합재료 회전원판의 면내응력 해석)

  • Koo Kyo-Nam
    • Composites Research
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    • v.18 no.4
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    • pp.8-13
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    • 2005
  • Rotating circular disks are widely used in data storage devices as well as in traditional industrial machines. Faster rotating speed is required in data storage devices for higher data transfer rate. In this Paper an application of composite materials to CD is proposed to increase critical speeds and the strength analysis was performed. A differential equation of displacement is derived for the analytic stress distribution of rotating polar orthotropic disk. The stress distributions for typical GFRP and CFRP disks and the maximum allowable speeds subjected to a constraint of tensile strength are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

Optically induced rotation of combined Mie particles within an evanescent field of a gaussian beam (가우스형 에바네슨트파의 광압에 의한 Mie 입자 결합체들의 회전)

  • 송영곤
    • Korean Journal of Optics and Photonics
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    • v.10 no.1
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    • pp.5-9
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    • 1999
  • We demonstrate a windmill type rotation of combined Mie particles caused by the evanescent field generated at the surface of a Gadolinium Gallium Garnet prism where a linearly polarized Nd:YAG laser beam (of wavelength 532 nm and power 100 mW) is totally reflected. The combined particles (e.g., doublets, triplets or quadruplets) consisting of polystyrene latex (or yeast) spheres with diameters of 3~5 m are reported to rotate at 0.1~1 rpm in water when the particles are slightly displaced from the center of the evanescent field.

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A Study on the Initial Shear Strength Characteristics of Sudden Gelation Grout (순결형 그라우트의 초기 전단강도 특성에 대한 연구)

  • Heo, Hyung-Seok;Park, Inn-Joon
    • Journal of the Korean Geotechnical Society
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    • v.36 no.9
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    • pp.33-44
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    • 2020
  • In order to analyze the shear strength characteristics of the grout with sudden gelation in the pre-hardening state, the viscosity of the mixture and the indoor vane shear test were performed. The grout was prepared according to the water-cement (w/c) ratio and the shear strength test was conducted. The plastic-state shear strength of grout was affected by the w/c ratio, so the lower the w/c ratio, the higher the initial shear strength was, and the longer the curing time was, the higher the shear strength was. The maximum shear strength occurred at the faster rotation angle as the higher shear strength was developed, and the lower shear strength occurred at the larger rotation angle. In addition, it was confirmed that the pre-hardening grout rapidly decreased in strength after the maximum shear strength was gained, and converged at a certain level after the rotation angle of the vane blade was about 70° to 90°.

750kW급 대형 수평축 풍력발전용 복합재 회전날개의 경량화 및 설계개선에 관한 연구

  • 공창덕;방조혁;정종철;강병훈;정석훈;김종식;류지윤
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1999.04a
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    • pp.28-28
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    • 1999
  • 본 연구는 이전 연구에서 500KW급 중형 수평축 발전기를 설계하였던 경험을 토대로 750KW급 대형 수평축 풍력발전용 복합재 회전날개를 개발하기 위해 수행되었다. 회전날개의 대형화에 따른 구조강도 확보 및 경량화 문제를 해결하기 위해 날개의 단면구조를 변경하였고, 주 하중을 받는 스파부분을 보강하였으며, 취급이 어렵고 가격이 비싼 노맥스 허니컴 대신에 폼을 사용한 샌드위치 구조를 적용하였다. 또한 경량화를 위해 금속재 플렌지형 허브부분 접합방식을 삽입볼트 접합방식으로 구조 설계를 변경하였다. 이러한 복합재 회전날개의 구조적 안정성을 확인하기 위해 상용 유한요소 해석 코드인 NISA II를 사용하였으며, 선형정적해석, 고유진동수해석, 국부 좌굴해석 등을 수행하여, 무게의 증가는 최대한 억제하면서 대형화에 따른 구조강도의 확보가 이루어졌음을 확인하였고, 피로수명해석을 통하여 20년 이상의 요구 수명을 만족함을 확인하였다.

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Application of Equivalent Ellipses for the Qualification of the Spatial Scale of Rainfall Event (호우사상의 공간규모 정량화를 위한 등가타원의 적용)

  • Kim, Ha-Young;Park, Chang-Yeol;Yoo, Chul-Sang
    • Journal of Korea Water Resources Association
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    • v.44 no.4
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    • pp.327-338
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    • 2011
  • This study examined the quantification problem of a storm shape using the concept of equivalent ellipses. The equivalent ellipses of a storm event were estimated at every time step with respect to the several thresholds of rainfall intensity, which was also examined in terms of their size and number. In addition, the average equivalent ellipse was decided, and the confidence intervals of major axis, minor axis, and rotational angle were calculated to evaluate if the average equivalent ellipse could be the representative one. As results, the following results could be derived. First of all, the number of equivalent ellipses and the size of equivalent ellipses increase as the threshold increase. Secondly, the appropriate ratio of major and minor axises of equivalent ellipse is 2 : 1. Finally, the average rotational angle estimated with respect to several threshold rainfall intensities were all found not to be statistically different from that of all representative rotational angles.

The Weld Strength and Design Tables for the Unstiffened Seated Connections (비보강받침접합의 용접강도와 설계도표)

  • Choi, Sun-Kyu;Yoo, Jung-Han;Lee, Kang-Min;Park, Jai-Woo
    • Journal of Korean Society of Steel Construction
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    • v.24 no.2
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    • pp.199-206
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    • 2012
  • Unstiffened seated connections (USC) ensure easy installation and safety during erection, thereby making the process more economical. USCs consist of a seat angle for carrying the beam's reactions and a top angle to provide beam stability. These angles are bolted or welded to the beam and supporting member. This paper sought to propose a design table for the weld strength of such connections obtained from the elastic vector method (EVM) and the instantaneous center-of-rotation method (ICM) in terms of calculating the eccentricity. Also, the proposed design table is compared with both AISC and KBC specifications.

A Experimental Study on Strength Safety of Rail Steel using Gas Pressure Welding (레일 가스압접부의 강도 안전성에 관한 실험적 연구)

  • Kim, Kyung-Seob
    • Journal of the Korean Society for Railway
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    • v.15 no.3
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    • pp.266-271
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    • 2012
  • This study was carried out for the purpose of improving driving safety and comfort of the railways quickly becoming popular. To conducted gas pressure welding to ensure the strength safety of continuous welded rail and rotating bending test tensile test was conducted. The element to determine the tensile strength of gas pressure welds at experiments be attributed to more upsetting length than pressure, according to increases of upsetting length, from brittle fracture to ductile fracture was observed. Through the biopsy of the fracture surface, according to the presence of brittle fracture could be evaluated to strength safety. In addition, mechanical strength of gas pressure welding depending on changes in upsetting length was different. Rotary bending test results were obtained to the infinite life according to exhibited higher fatigue limit of 373MPa at upsetting length 25mm.

회전성형 프로세스의 회전운동 제어에 관한 연구

  • 이완규;최만용;임순재
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.04b
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    • pp.454-457
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    • 1994
  • 회전성형가공(Rotation molding)은 사출성형등에 비해 제품의 크기, 형상에 제약이 거의 없고 동일한 설비에서 금형의 교한만으로 다양한 제품을 생산할 수 있기 때문에 최근 국내외적으로각광을 받기 시작 하고 있다. 회전성형가공은 금형의 외부에 고온의 열을 가하면서 2축방향으로 동시에 회전을 시켜 금형 내부의 수지를 금형내부에 균일하게 용착시켜 제품을 생산하는 과정으로, 일반적으로 제품의 강도보다는 제품치수의 정도 및 치수(예를들면 두께)의 균일성이 가공상의 중요한 문제가 된다. 본 연구에서는 회전성형프로세스의 최적제어를 위한 목적으로금형의 회전운동에 관해 검토한다. 먼저 금형의 회전운동에 관한 수학적모델을 작성하고 금형 내부의 수지가 균일한 운동을 할수 있는 금형의 회전 경로를 생성하는 2축 의 회전비의 관계를 구하는 방법에 관해 검토하였다. 다음 시뮬레이션을 통하여본 방법의 타당성에 대해 검토하였다.

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Behavior of CFT Column to H-Beam Full-Scale Connections with External T-Stiffeners (T-스티프너 보강 CFT 기둥 - H형강보 실대형 접합부의 거동)

  • Kim, Young Ju;Kang, Chang Hoon;Shin, Kyung Jae;Oh, Young Suk;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.13 no.6
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    • pp.715-723
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    • 2001
  • This paper represents the behavior of CFT column to H-beam full-scale connection with external T-stiffener. 6 specimens whose T-stiffeners which are compounded of vertical element and horizontal element were made under the parameter of the strength ratio of each elements(vertical element and horizontal element in T-stiffener) to the beam full plastic moment. The analysis-parameters demonstrated in the base of the data that we get in experiment are strength stiffness, and plastic rotational capacity. All of specimen showed stable hysteretic behavior, and the horizontal element is more critical than vertical element in strength and stiffness. The mean beam plastic rotation of all specimen except the TS-2 specimen is 2.97% rad.

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Development of automated manufacturing equipment paving stone (페이빙스톤 자동 제조장치를 위한 연구)

  • Oh, Seong-Hun;Kim, Ho-Keon;Kim, Jeong-Jin
    • Proceedings of the KAIS Fall Conference
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    • 2011.05b
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    • pp.974-976
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    • 2011
  • 수석을 가공하기 위해서 회전 통 안에 피연마물을 투입하고 이를 회전 시키면 피연마물 자체의 마찰과 동체와의 마찰로 연마가 된다. 본 연구는 복수의 석재가 회전드럼에 투입되고 회전드럼이 회전을 하면 회전드럼 내측 벽에 개별적으로 고정되어있는 폐비닐로 이루어져있는 패드가 복수의 석재를 회전드럼이 회전하는 방향으로 견인하여 회전드럼에 투입된 복수의 석재가 서로 충돌하여 석재의 거친 면이나 날카로운 모서리가 부드럽게 연마될 수 있도록 하고, 폐비닐로 이루어져있는 패드는 석재에 발생되는 충격을 흡수하고 기존의 패드보다 강도를 크게 향상시키고 훼손된 패드만 교체할 수 있도록 고안하였다.

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