• Title, Summary, Keyword: 준 정적 실험

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Semi-Dynamic Digital Video Adaptation System for Mobile Environment (모바일 환경을 위한 준-동적 디지털 비디오 어댑테이션 시스템)

  • 추진호;이상민;낭종호
    • Journal of KIISE:Software and Applications
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    • v.31 no.10
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    • pp.1320-1331
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    • 2004
  • A video adaptation system translates the source video stream into appropriate video stream while satisfying the network and client constraints and maximizing the video quality as much as possible. This paper proposes a semi-dynamic video adaptation scheme, in which several intermediate video streams and the information for the measuring of video quality are generated statically. The intermediate video streams are generated by reducing the resolution of the video stream by a power of two several times, and they are stored as the intermediate video streams on the video server. The statically generated information for the input video stream consists of the degrees of smoothness for each frame rate and the degree of frame definition for each pixel bit rate. It helps to dynamically generate the target video stream according to the client's QoS at run-time as quickly as possible. Experimental result shows that the proposed adaptation scheme can generate the target video stream about thirty times faster while keeping the quality degradation as less than 2% comparing to the target video stream that is totally dynamically generated, although the extra storages for the intermediate video streams are required.

Moving Support Elements for Dynamic Finite Element Analysis of Statically Determinate Beams Subjected to Support Motions (지점운동을 받는 정정보의 동해석을 위한 동지점 유한요소 개발)

  • Kim, Yong-Woo;Jhung, Myung Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.4
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    • pp.555-567
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    • 2013
  • A finite element formulation for a Rayleigh-damped Bernoulli-Euler beam subjected to support motions, which accompanies quasi-static rigid-body motion, is presented by using the quasi-static decomposition method. Moving support beam elements, one of whose nodes is coincident with the moving support, are developed to represent the effect of a moving support. Statically determinate beams subjected to support motions can be modeled successfully by using moving support elements. Examples of cantilever and simply-supported beams subjected to support motions are illustrated, and the numerical results are compared with the analytical solutions. The comparison shows good agreement.

Enhancement of SNUF Active Trailing-edge Flap Blade Mechanism Design (SNUF뒷전 플랩 블레이드 메커니즘의 설계 개선)

  • Natarajan, Balakumaran;Eun, WonJong;Shin, SangJoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.7
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    • pp.645-653
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    • 2013
  • Seoul National University flap(SNUF) blade is a small-scale rotor blade incorporating a small trailing-edge flap control surface driven by piezoelectric actuators at higher harmonics for vibration attenuation. Initially, the blade was designed using two-dimensional cross-section analysis and geometrically exact one-dimensional beam analysis, and its material configuration was finalized. A flap-deflection angle of ${\pm}4^{\circ}$ was established as the criterion for enhanced vibration reduction based on an earlier simulation. The flap-linkage mechanism was designed and static bench tests were conducted for verifying the performance of the flap-actuation mechanism. Different versions of test beds were developed and tested with the designed flap and the selected APA 200M piezoelectric actuators. Through significant improvements, a maximum deflection of ${\pm}3.7^{\circ}$ was achieved. High-frequency experiments were conducted for evaluating the performance, and the transfer function of the test bed was determined experimentally. With the static tests almost complete, the rotor power required for testing the blade in a whirl tower (centrifugal environment) was calculated, and further preparations are underway.

Performance and Root Mean Squared Error of Kernel Relaxation by the Dynamic Change of the Moment (모멘트의 동적 변환에 의한 Kernel Relaxation의 성능과 RMSE)

  • 김은미;이배호
    • Journal of Korea Multimedia Society
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    • v.6 no.5
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    • pp.788-796
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    • 2003
  • This paper proposes using dynamic momentum for squential learning method. Using The dynamic momentum improves convergence speed and performance by the variable momentum, also can identify it in the RMSE(root mean squared error). The proposed method is reflected using variable momentum according to current state. While static momentum is equally influenced on the whole, dynamic momentum algorithm can control the convergence rate and performance. According to the variable change of momentum by training. Unlike former classification and regression problems, this paper confirms both performance and regression rate of the dynamic momentum. Using RMSE(root mean square error ), which is one of the regression methods. The proposed dynamic momentum has been applied to the kernel adatron and kernel relaxation as the new sequential learning method of support vector machine presented recently. In order to show the efficiency of the proposed algorithm, SONAR data, the neural network classifier standard evaluation data, are used. The simulation result using the dynamic momentum has a better convergence rate, performance and RMSE than those using the static moment, respectively.

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On the Grounding Damage of Ship Bottom Stiffened Platings(Part I: Experiment) (좌초시 선저보강판의 손상에 관한 연구(제1보: 실험))

  • Jeom-K. Paik;Myung-H. Hyun;Tak-K. Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.31 no.1
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    • pp.121-132
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    • 1994
  • The aim of the present paper is to clarify the damage characteristics fur ship bottom stiffened platings in grounding. For this purpose, a series of tests are performed. A rigid wedge is quasi-statically pushed into the high tensile steel plates with two stiffeners. The aspect ratio of plates(a/B) is in the range from 1.0 to 2.5 and the thickness of plates is in the range from 3.4 to 7.0mm. Also other parameters, namely the shape of wedge tip, wedge angle and property/direction of stiffeners are varied. The test is carried out using the 100ton universal test machine. During the loading. both applied force and length of cutting(penetration) resulting in the grounding force-penetration response are measured.

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Parametric Study on the P-M Interaction Diagram of Hollow Prestressed Concrete Bridge Columns (중공 프리스트레스트 콘크리트 교각의 P-M 상관도 매개변수 분석)

  • Kim, Tae-Hoon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.15 no.6
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    • pp.1-10
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    • 2011
  • This study presents the results of parametric studies of the P-M interaction diagram of hollow prestressed concrete bridge columns. Among the numerous parameters, this study concentrates on concrete compressive strength, prestressing steel reinforcement ratio, effective prestress, the Ds/Do ratio, and the Di/Do ratio. The strength and ductility of hollow prestressed concrete bridge columns were evaluated through quasistatic tests. The P-M interaction diagrams from the codes were different from that of the results, which were in good agreement with AASHTO-LRFD. Nondimensionalized P-M interaction diagrams were developed to predict the design resistance of hollow prestressed concrete bridge columns.

Determination of Key Influence Parameters on RC Joint Shear Behavior Using the Bayesian Parameter Estimation (Bayesian parameter estimation을 적용한 RC 접합부 전단거동의 주요영향 요인 결정)

  • Kim, Jae-Hong;Yang, Jong-Ho;Im, Duk-Ki
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.328-331
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    • 2011
  • 준정적 횡하중을 재하 받는 철근콘크리트 보-기둥 접합부의 전단강도에 대한 주요 영향요인을 Bayesian parameter estimation의 신뢰성 이론 접목을 통해 검토하였다. 이와 같은 연구 scope의 수행을 위해 철근콘크리트 보-기둥의 실험 database가 구축되었다. 실험 database는 일정한 criteria을 적용하여 구축되었으며, 포함된 시편들은 최종적으로 접합부 내의 전단파괴가 지배하는 경우들이다. 포함된 시편들의 상세는 ACI (American Concrete Institute) 352R-02를 기준으로 평가되어졌다. 보-기둥 접합부의 전단강도에 영향 요인을 편중되지 않게 평가하고자, Bayesian parameter estimation의 신뢰성 이론을 적용하였다. Bayesian parameter estimation의 적용을 통해 전단강도에 영향이 적은 변수 (not informative parameter)를 순차적으로 제거 (stepwise removal process)함으로 주요 영향요인의 우선 순위를 확인할 수 있었다. 검토된 8개의 변수들 중에서, 횡하중을 재하 받는 철근콘크리트 보-기둥의 전단강도는 주로 콘크리트 압축강도, in-plane geometry, 종방향 보의 주철근 그리고 접합부 내의 구속철근 순으로 영향을 줌을 알 수 있었다.

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Study on the Seismic Behavior of Precast Concrete Segmental Bridge Piers with Shear Resistance Connecting Structure (전단저항 연결체를 갖는 프리캐스트 세그먼트 교각의 지진거동에 관한 연구)

  • Kim, Tae-Hoon;Kim, Young-Jin;Kim, Seong-Woon;Kim, Chul-Young;Shin, Hyun-Mock
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.85-88
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    • 2008
  • The purpose of this study was to investigate the seismic behavior of precast concrete segmental bridge piers with shear resistance connecting structure. A model of precast concrete segmental bridge columns with shear resistance connecting structure was tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. The proposed numerical method for the seismic behavior of precast concrete segmental bridge piers with shear resistance connecting structure is verified by comparison with reliable experimental results.

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Seismic Performance of Internally Confined Hollow RC Column with Corrugated Steel Tube (파형강관 내부 구속 중공 철근 콘크리트 기둥의 내진 성능)

  • Han, Taek-Hee;Kim, Jong-Min;Kang, Jun-Suk;Kang, Young-Jong
    • Journal of Korean Society of Hazard Mitigation
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    • v.8 no.2
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    • pp.31-38
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    • 2008
  • A column test was performed far a new-type column with a quasi static test. An internally confined hollow reinforced concrete column with a corrugated steel tube (ICH RC-CT column) was tested to evaluate its seismic performance. And also, a general solid RC column was tested fur the comparison. The test was performed as planned drift levels. The lateral displacements and the lateral loads of column specimens were measured during tests. From the test results, the ICH RC-CT column showed smaller energy absorbing capacity than a solid RC column but showed the almost equal energy ductility and equivalent viscous damping ratio to those of the solid RC column.

Seismic Performance of a Hollow Composite Column (강합성 중공 기둥의 내진 성능)

  • Han, Taek Hee;Kim, Jung Hun;Lim, Nam Hyoung;Kang, Young Jong
    • Journal of Korean Society of Steel Construction
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    • v.20 no.2
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    • pp.215-226
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    • 2008
  • A column test was performed for a hollow composite column to evaluate its seismic performance. The seismic performances of a hollow composite column and a reinforced concrete (RC) column were evaluated and compared by quasi-static tests. Lateral displacements and lateral loads of the column specimens were measured during tests. Ductilities, absorbed energy, equivalent damping ratios, and damage indices were calculated from the recorded data. From the test results, the hollow composite column showed a seismic performance superior to the column in terms of double moment capacity, ultimate energy, and energy absorption.