• Title, Summary, Keyword: 원통

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Wave Interpretation of Forced Vibration of Finite Cylindrical Shells (탄성파를 이용한 유한 원통셸의 강제진동 해석)

  • 길현권
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.2
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    • pp.83-89
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    • 1999
  • The forced vibration of a finite cylindrical shell has been analyzed from an elastic wave viewpoint. The displacement vector is used to formulate the vibration field, that is regarded as a superposition of disturbances due to elastic waves propagating on the shell. The reflection matrix is also used in the formulation of the vibration field, that is easily derived in the present approach. It allows one to easily identify the wave conversion of elastic waves at the ends of the shell. The present approach is used to predict the vibration field of the cylindrical shell with free-free boundary conditions. The contribution of each type of elastic waves into the vibration field was identified, and the wave conversion at the ends of the shell was observed. Those results showed that the present approach can be effectively used to analyze the forced vibration of the cylindrical shell from an elastic wave viewpoint.

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Postbuckling and Vibration Analysis of Cylindrical Composite Panel subject to Thermal Loads (열하중을 받는 복합적층 원통형 패널의 좌굴후 거동 및 진동해석)

  • Oh, Il-Kwon;Lee, In
    • Journal of the Korea Institute of Military Science and Technology
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    • v.2 no.2
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    • pp.148-156
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    • 1999
  • The thermal postbuckling and vibration characteristics of cylindrical composite panel subject to thermal loads are analyzed using finite elements. The von-Karman nonlinear displacement-strain relation based on the layerwise theory is applied to consider large deflections due to thermal loads. Cylindrical arc-length method is used to take into account the snapping phenomena. Thermal snapping and vibration characteristics are investigated for various structural parameters such as thickness ratio, shallowness angle and boundary conditions. The present results show that thermal snapping changes the mode shapes as well as static deformations.

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Preliminary evaluation of a tapered cylindrical shock wave source (테이퍼 형상을 가지는 원통형 충격파 발생기의 특성 평가)

  • Choi M. J.;Cho S. C.;Kang K. S.;Paeng D. G.;Lee J. S.
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.379-384
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    • 2004
  • 체외 충격파 쇄석술 (ESWL)은 체외에서 발생된 충격파를 체내의 결석이 위치한 부위에 집속하여 결석을 분쇄하는 비 침습적인 치료술이다. 최근 충격파를 이용하여 근관절 질환을 치료하는 체외 충격 파 치료술 (ESWT)이 또한 임상적으로 주목을 받고 있다. 아직 ESWT를 위한 최적의 충격파 노출 조건은 알려져 있지 않지만, 일반적으로 ESWL에 비해 상대적으로 충격파장의 초점 영역이 넓고 낮은 강도의 충격파를 사용한다. 본 연구에서는 ESWT에 적합할 것으로 예상되는 테이퍼 원통형 충격파 발생 방식을 제안하고자 한다. 본 연구에서는 테이퍼 원통형 충격 파 발생 의 초점 부위의 파형을 수치 해석하여 평가하고, 기존 원통형의 경우와 비교하였다. 테이퍼 원통형 충격파 발생기의 시제품을 제작하고, 발생된 강도를 평가하기 위해, 모의 결석을 제작하여 분쇄 효율을 측정하였으며, 결과를 원통형 충격파 발생기와 비교하였다.

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Analysis of Radiation Patterns of Inverted-F Antenna(IFA) on Cylindrical Conducting Body (원통 도체 위에 장착된 역 F 안테나의 방사 패턴 분석)

  • Kim Tae-Hyun;Kim Sung-Wan;Lee Jae-Deuk;Park Dong Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.5
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    • pp.518-525
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    • 2005
  • In this paper, radiation patterns are simulated and analyzed for inverted-F antenna(IFA) on a cylindrical conducting body like a satellite launcher. First, parametric studies are performed for IFA itself to analyze its characteristics. Then, IFAs on a cylindrical conducting body are simulated and analyzed. Especially, by changing the number of IFAs, the length and the diameter of the cylinder radiation patterns are simulated and analyzed. Finally, IFAs on a cylindrical conducting body are fabricated and their return losses and radiation patterns are measured. Good agreements are observed between the simulated and measured results.

Characteristics of Radiated Electromagnetic Fields From A Cylindrical Cavity (원통형 캐비티에서 방출되는 방사 전자파 특성)

  • Kim, Hyo-Gyun;Cho, Jun-Ho;Lim, Dong-young;Kim, Ki-Chai
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.2
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    • pp.237-244
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    • 2016
  • This paper, presents the characteristics of electromagnetic fields radiated from a pole-transformer. The cylindrical cavity is used to measure electromagnetic fields radiated from a pole-transformer when partial discharge occures inside the pole-transformer. The theoretical analysis is conducted by a finite difference time domain (FDTD) method. As a result, frequency characteristics of the radiated electromagnetic waves emitted from the inside the cavity to the outside through the 1st and 2nd bushings could be observed for the configuration of the cylindrical cavity with a radiation window. The frequency characteristics of electromagnetic field are also studied according to the enclosure structure of the cylindrical cavity. To verify the theoretical analysis, computed results are compared to experimental results.

Experimental study on the damping characteristics of a cylindrical structure containing oil and bearing balls (윤활유와 베어링 볼을 내장한 원통형 구조물의 감쇠특성에 관한 실험적 연구)

  • 류봉조;송선호
    • Journal of KSNVE
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    • v.6 no.1
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    • pp.107-114
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    • 1996
  • The damping characteristics of a cylindrical structure containing oil and bearing balls is investigated for external bending forces. The experimental data obtained through the use of bearing balls with viscous oil in a column is given and analyzed. The viscous action of the oil and inertia effects of the balls on the inside of column create a drag force. The drag force dampens the vibration of the column. This study aims to search for an optimum combination of oil and balls which would produce maximum damping. Machining oils of various viscosities along with ball bearings of various sizes place inside cantilevered aluminium tubes of various diameters to create a rig on which the damping properties of the oil and balls can be studied. The contileved tubes are studied in both horizontal and vertical positions in order to gauge the effect of gravity on the system. The actions of the ball in the column and damping characteristics are investigated according to the dimensionless terms. The Buckingham theorem is used to reduce the variables and to predict the damping of an oil ball column. Though the damping ratio remains fairly constant in the horizontal position of column, the damping ratio begins to increase as the ratio of the number of balls and column length rise above 0.28 in the vertical position of oil ball column. The ratio of the ball diameter to column diameter influences the damping ratio with an optimum diameter ratio. Slenderness ratio and gravity effects on the damping ratio ane investigated.

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Study on Analysis of Evanescent Waves Generating the Strong End Axial Vibration of a Finite Cylindrical Shell (유한 원통셸의 큰 끝단 종진동을 발생시키는 감쇠파에 대한 분석 연구)

  • Kil, Hyun-Gwon
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.7
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    • pp.361-367
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    • 2011
  • Propagating waves (flexural, longitudinal and shear waves) travelling with constant amplitudes and evanescent waves decaying exponentially are generated on a cylindrical shell. Evanescent waves are generally generated in the vicinity of an vibration excitation point and near ends of the shell. But the evanescent waves can generates strong axial vibration at the ends of the cylindrical shell. The strong end axial vibration due to those evanescent waves has been observed in an author's previous paper dealing with measurements of the in-plane axial vibration of a finite cylindrical shell. In this paper the strong end axial vibration due to the evanescent waves has been theoretically analyzed. In order to analyze the vibration of the cylindrical shell, wave propagation approach has been implemented. Comparison between theoretical and experimental results for the axial vibration of the shell showed that the strong evanescent wave can be generated due to mode conversion (conversion from flexural wave to evanescent wave) at the ends of cylindrical shell. It also showed that the evanescent wave can generate the strong axial vibration near the ends of the cylindrical shell and that it can have effect even on 1/3 of the total length of the shell.

A Study on Behavior of Anisotrpic Circular Cylingdrical Shell including Large Deformation Effects (대변형 효과를 고려한 비등방성 원통형 쉘의 거동에 관한 연구)

  • Chun, Kyoung Sik;Son, Byung Jik;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.14 no.4
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    • pp.489-497
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    • 2002
  • Nonlinear behavior and large deformation cannot be analyzed using techniques based on linear theory. Nonetheless, they are emerging as gradually huge and complex structures. In addition, the optimum design of structure is necessary in the development of high-performance computation and numerical methods. as well as stricter design-criterion. Therefore, the structural problems in engineering that are limited to the linear region must be extended to the nonlinear region. Likewise, structural behavior must be accurately analyzed. In turn, this requires considering the expected problems beforehand. Only then can an efficient, economical, and optimized structure be designed. This paper presents the solution of the geometrical nonlinear problem of anisotropic cylindrical shell. The characteristics of the geometrical nonlinear behavior of anisotropic circular cylindrical shells may vary according to several causes. e.g., change of fibers, curvature in the circumferential direction, subtended angle, aspect, etc. Parametric studies were conducted to determine the effect of factors on the large deflection behavior of laminated shells, with interesting observations.

User-Defined Hand Gestures for Small Cylindrical Displays (소형 원통형 디스플레이를 위한 사용자 정의 핸드 제스처)

  • Kim, Hyoyoung;Kim, Heesun;Lee, Dongeon;Park, Ji-hyung
    • The Journal of the Korea Contents Association
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    • v.17 no.3
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    • pp.74-87
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    • 2017
  • This paper aims to elicit user-defined hand gestures for the small cylindrical displays with flexible displays which has not emerged as a product yet. For this, we first defined the size and functions of a small cylindrical display, and elicited the tasks for operating its functions. Henceforward we implemented the experiment environment which is similar to real cylindrical display usage environment by developing both of a virtual cylindrical display interface and a physical object for operating the virtual cylindrical display. And we showed the results of each task in the virtual cylindrical display to the participants so they could define the hand gestures which are suitable for each task in their opinion. We selected the representative gestures for each task by choosing the gestures of the largest group in each task, and we also calculated agreement scores for each task. Finally we observed mental model of the participants which was applied for eliciting the gestures, based on analyzing the gestures and interview results from the participants.

Structural Analysis of the Pre-weakening of a Cylindrical Concrete Silo for the Application of Overturning Explosive Demolition Method (원통형 콘크리트 사일로의 발파해체 전도공법 적용을 위한 사전취약화 구조해석)

  • Choi, Hoon;Kim, Hyo-Jin;Park, Hoon;Yoon, Soon-Jong
    • Explosives and Blasting
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    • v.27 no.2
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    • pp.12-18
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    • 2009
  • Recently, several cases of destruction of old cylindrical silos by explosive demolition method have been reported. This study deals with the subject concerning the pre-weakening of a cylindrical concrete silo for the application of overturning explosive demolition method. In the past, the pre-weakening operation of structure in explosive demolition has been done by use of some empirical methods. These empirical approaches, however, have possibilities of unexpected accidents. In order to provide a guideline for the pre-weakening of cylindrical silos and similar structures, this paper shows the result of a case study, in which the instability of a silo due to pre-weakening is investigated by a numerical structural analysis before actually conducting pre-weakening and demolition operations.