• Title/Summary/Keyword: Simple Beam

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Flexural Analysis of Steel Fiber Rreinforced Concrete Beam (강섬유 보강 콘크리트 보의 휨 해석)

  • 이차돈
    • Computational Structural Engineering
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    • v.3 no.4
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    • pp.113-122
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    • 1990
  • An analytical simulation of the flexural behavior of SFRC beam has been illustrated. Curvature distributions and crack opening in critical region were taken into account. Compressive and tensile constitutive models which express post-peak behavior of SFRC with stress-crack opening relationships were incorporated in simulating nonlinear flexural behavior of the beam. The model was able to predict test results with reasonable accuracy. Behavior of the critical section and effects of different factors m the flexural behavior of SFRC beam were investigated. Simple observation and statistical approach have been made in selecting most influential parameters in flexural behavior of SFRC.

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A Unidirectional Beam Antenna using a Probe Excited Circular Ring near the Reflector

  • Phongcharoenpanich, Chuwong;Lamultree, Suthasinee;Kosulvit, Sompol;Krairiksh, Monai
    • Proceedings of the IEEK Conference
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    • 2002.07a
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    • pp.545-548
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    • 2002
  • This paper proposes a unidirectional beam antenna using a probe excited circular ring near the reflector. The antenna structure is simple. The radiation characteristics of the antenna fur various spacing between a probe excited circular ring and the reflector are analyzed. These characteristics are also compared with the conventional single aperture near the reflector. It is found that the proposed structure yields better characteristics than the conventional structure. The numerical results of the radiation pattern, elevational beam peak, beamwidth, and maximum directivity are investigated. The result of the analysis is very useful to design the antenna of the high directivity with unidirectional beam.

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Adaptive phase monopulse for simultaneous interference cancellation in sum and difference beams (합, 차 빔 내에서 가섭 신호 동시 제거를 위한 적응 위상 모노펄스)

  • 주경환;성하종;윤대희
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.3
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    • pp.142-150
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    • 1996
  • Monopulse technique has been widely used for a bearing estimation of a desired signal. This method can estimate the bearing of the signal with only one pulse, so computational load and complexity are low and its processes are simple. But if the desired signal incidents with interferences or multiple signals exist in the beams, the method fails to estimate correct signal angle. To solve this problem, the method to use adaptive array was proposed. In conventional adaptive array methods, sum beam was formed with fixed weights and ifference beam was formed with adaptive weights determined to minimize beamformer output power with one or more linear constraints, or an algorithm to minimize each sum beam and difference beams simultaneously using adaptively formed one basic beam. Theroretical analyses and simulation results show that the performance of the proposed method is superior to that of conventional algorithms.

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Feedforward Active Shock Response Control of a Flexible Beam (유연빔의 피드포워드 능동 충격응답 제어)

  • Pyo, Sang-Ho;Lee, Young-Sup;Shin, Ki-Hong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.213-216
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    • 2005
  • Active control method is applied to a flexible beam excited by a shock impulse by focusing on reducing the residual vibrations after the shock input. It is assumed that the shock input can be measured and is always occurred on the same point of the beam. If the system is well identified and the corresponding inverse system is designed reliably, it has shown that a very simple feed-forward active control method may be applied to suppress the residual vibrations without using an error sensor and adaptive algorithm. Both numerical simulation and experimental result show a promising possibility of applying to a practical problem.

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Optimal Layout Design of Frequency- and Temperature-Dependent Viscoelastic Materials for Maximum Loss Factor of Constrained-Layer Damping Beam (점탄성 물질의 온도와 주파수 의존성을 고려한 구속형 제진보의 최대 손실계수 설계)

  • Lee, Doo-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.1023-1026
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    • 2007
  • Optimal damping layout of the constrained viscoelastic damping layer on beam is identified with temperatures by using a gradient-based numerical search algorithm. An optimal design problem is defined in order to determine the constrained damping layer configuration. A finite element formulation is introduced to model the constrained damping layer beam. The four-parameter fractional derivative model and the Arrhenius shift factor are used to describe dynamic characteristics of viscoelastic material with respect to frequency and temperature. Frequency-dependent complex-valued eigenvalue problems are solved by using a simple resubstitution algorithm in order to obtain the loss factor of each mode and responses of the structure. The results of the numerical example show that the proposed method can reduce frequency responses of beam at peaks only by reconfiguring the layout of constrained damping layer within a limited weight constraint.

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Numerical investigation of continuous hollow steel beam strengthened using CFRP

  • Keykha, Amir Hamzeh
    • Structural Engineering and Mechanics
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    • v.66 no.4
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    • pp.439-444
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    • 2018
  • This paper presents a numerical study on the behavior of continuous hollow steel beam strengthened using carbon fiber reinforced polymers (CFRP). Most previous studies on the CFRP strengthening of steel beams have been carried out on the steel beams with simple boundary conditions. No independent study, to the researcher's knowledge, has studied on the CFRP strengthening of square hollow section (SHS) continuous steel beam. However, this study explored the effect of the use of adhesively bonded CFRP flexible sheets on the behavior of the continuous SHS steel beams. Finite Element Method (FEM) has been employed for modeling. Eleven specimens, ten of which were strengthened using CFRP sheets, were analyzed under different coverage length, the number of layers, and the location of CFRP composite. ANSYS software was used to analyze the SHS steel beams. The results showed that the coverage length, the number of layers, and the location of CFRP composite are effective in increasing the ultimate load capacity of the continuous SHS steel beams. Application of CFRP composite also caused the ductility increase some strengthened specimens.

Measurement of Viscoelastic Properties of Damping Materials using Beam Transfer Function Method (보 전달함수법을 이용한 제진재의 점탄성 특성 측정)

  • Kim, Seung-Joon;Lee, Je-Pil;Park, Jun-Hong;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.286-289
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    • 2008
  • Damping materials are widely used to reduce vibration or noise generation of structures. To understand their damping capability and for use in numerical simulations, their viscoelastic properties should be measured in the frequency range of interest. In this study, experimental setup is proposed to measure materials properties of very compliant polymer materials. The polymer materials used in this study are difficult to form into rod shapes, and typical resonance methods are not applicable. In the proposed measurement setup, the damping materials were modeled as a simple viscoelastic support at one end of the beam. Their properties were measured through analysis of their effects on the wave propagation characteristics of the beam structure.

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A Survey Tool for the Measurements of the Rock Parting Surfaces (암반의 불연속면 배열을 측량하는 원격 영상측량기)

  • 황상기;임유진
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.697-704
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    • 2000
  • This study presents methodology and tools for remote measurement of the orientation of the rock parting surfaces. Two close circuit video camera capture the pictures of a rock excavation surface while a laser beam scans the surface. Positions of the laser beams in the two digital images are recognized by image processing. Using the stereoscopic concept, three dimensional coordinations of the rock surface and the orientation of the rock parting planes are calculated. Point, cross and line type laser beams are tested for better image processing results and measurement accuracy of the coordinates. According to a simple accuracy test, cross beam show better results than the point beam. However, line beam show more promising results for the measurement of the rock parting surfaces.

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Development of the Side Scan Sonar Using the Multi-beam Sensors : Sensor Design (멀티빔 센서를 이용한 사이드 스캔 소나 개발 : 센서 설계)

  • Chang, Yu-Shin;Keh, Joong-Eup;Jo, Heung-Gi;Lee, Man-Hyung
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.10
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    • pp.581-586
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    • 2005
  • The multi-beam side scan sonar system uses the towfish installed sonars, it is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. Recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. Therefore, this research develops multi-beam sensors for a side scan sonar that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

Evaluation of Dynamic Characteristics of Rubber Materials Using a Double Cantilever Sandwich Beam Method (양팔 샌드위치보 시험법에 의한 EPDM고무의 동특성 평가 연구)

  • Kim, Kwang-Woo;Choi, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1393-1400
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    • 2002
  • A double cantilever sandwich-beam method has been applied to the evaluation of the frequency dependence of dynamic elastic modulus and material loss factor of EPDM rubbers. The flexural vibration of a double cantilever sandwich-beam specimen with an inserted rubber layer was studied using a finite element simulation in combination with the sine-sweep test. Effects of the rubber layer length on the dynamic characteristics were also investigated: reliable values were measured when the length of the inserted rubber layer was larger than and equal to 50% of the effective specimen length. The values were compared with those obtained by the dynamic mechanical analysis and the simple resonant test. Relationships of the dynamic characteristics of rubbers with frequency could be determined using the least square error method.