• Title, Summary, Keyword: 에너지 소산

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A Numerical Study on Acoustic Damping Induced by Gap between Baffled Injectors in a Model Rocket Combustor (모형 로켓 연소실에서 배플형 분사기의 간극에 의한 음향 감쇠 효과에 관한 수치적 연구)

  • Sohn, Chae-Hoon;Lee, Jung-Yun
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.3
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    • pp.35-42
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    • 2007
  • Acoustic damping induced by gap width between baffled injectors is investigated numerically, which are installed to suppress pressure oscillations in a model rocket combustor. The previous work reported that the baffled injectors show larger acoustic damping with the gap width between injectors. It is simulated numerically and its mechanism is examined. Damping factors are calculated as a function of gap width and it is found that the optimum gap is 0.1 mm or so. For understanding of the improved damping induced by the gap, dissipation rate of turbulent kinetic energy and vorticity are calculated as a function of the gap. Both parameters have their maximum values at the specific gap and especially, the dissipation rate has the same profile as that of damping factor. It verifies that the improved damping made by the gap is attributed to the increased acoustic-energy dissipation.

Assessment of Energy Dissipation Capacity of Reinforced Concrete Members Subjected to Cyclic Loading (반복하중을 받는 철근콘크리트 부재의 에너지 소산능력 평가)

  • Kim, Min-Ok;Cha, Sang-A;Lee, Jung-Yoon
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.135-136
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    • 2010
  • In this paper, using nonlinear finite element analysis program, we verify the energy dissipation mechanism through stress-strain curve of material with applied steel and concrete acting role of reinforced concrete (RC) column that subjected to cyclic loading with axial force

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Equivalent Damping Ratio of a SDOF Structure Combined with Coulomb and Viscous Damping (점성 및 마찰감쇠가 있는 단자유도 구조물의 등가감쇠비)

  • Seong, Ji-Young-Suck;Min, Kyung-Won
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.449-453
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    • 2010
  • 본 논문에서는 점성 및 감쇠가 있는 단자유도 구조물의 등가감쇠비를 효율적으로 구하는 방법을 제시하였다. 건물에 설치된 마찰감쇠기는 외력의 크기에 따라 정지와 운동의 상태를 반복하여 외부 입력에너지를 소산시키기 때문에 외력과 응답관계가 비선형이다. 마찰감쇠기가 설치된 단자유도 건물은 마찰감쇠기외에 점성감쇠가 동시에 존재하므로 해석적인 정해를 구하기가 어렵다. 등가감쇠비를 산정하기 위해서 첫째, 점성과 마찰감쇠가 있는 단자유도계 건물의 자유진동 정해를 통하여 변위응답과 가속도 응답특성을 분석하였다. 둘째, 자유진동의 경우 응답이 멈출 때까지 소산에너지식을 이용하여 등가점성감쇠비를 구하였다. 셋째, 조화가진 일 때는 수치해석을 통하여 마찰력비 $F_r$에 따른 응답 특성을 알아보았다. 넷째, 조화가진의 경우 에너지 균형식을 바탕으로 등가점성감쇠비를 유도하였다. 등가점성감쇠비는 변위응답비의 영향을 받으므로 응답을 알아야만 구할 수 있다. 건물 응답의 진동수 특성은 협소영역(narrow band)이므로 고유진동수에 의해 지배된다고 가정하여 등가점성감쇠비를 구하였다. 마지막으로, 유도한 자유진동과 조화가진의 등 가점성감쇠비를 이용한 등가선형운동방정식의 해를 비선형 수치해석 한 결과와 비교하여 검증하였다.

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Ductility Capacity of Shear-Dominated Steel Plate Walls (전단지배 강판벽의 연성능력)

  • Park, Hong Gun;Choi, In Rak;Jeon , Sang Woo;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.457-468
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    • 2006
  • An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

Experimental study on a Cantilever Type Metallic Damper for Seismic Retrofit of Building Structures (건물의 내진보강을 위한 캔틸레버타입 강재댐퍼의 실험)

  • Ahn, Tae-Sang;Kim, Young-Ju;Park, Jin-Hwa;Kim, Hyung-Geun;Jang, Dong-Woon;Oh, Sang-Hoon
    • Journal of Korean Society of Steel Construction
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    • v.24 no.2
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    • pp.149-161
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    • 2012
  • The use of seismic energy-dissipative devices for passive control is increasing exponentially in the recent years for both new and existing buildings. Use of these devices started in and has been somewhat limited to developed countries. One of the current challenges is to promote the use of seismic dampers in earthquake-prone developing countries by lowering the cost of the devices. This paper proposed a new type of seismic damper based on yielding of a cantilever type metallic element for seismic retrofit of existing and new building structures. The hysteretic behavior and energy dissipation capacity of the proposed damper was investigated using component tests under cyclic loads. The experimental results indicated that the damping device had stable restoring force characteristics and a high energy dissipation capacity. Based on these results, a simple hysteretic model for predicting the load-displacement curve of the seismic damper was proposed.

Cyclic Test of Shear Wall Damping Systems (전단벽 제진시스템의 반복가력실험)

  • Ahn, Tae Sang;Kim, Young Ju;Kim, Hyung Geun;Jang, Dong Woon;Choi, Kyoung Kyu;Kim, Jong Rak
    • Journal of Korean Society of Steel Construction
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    • v.25 no.1
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    • pp.81-92
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    • 2013
  • The objective of conventional seismic design is to ensure an acceptable safety level while avoiding catastrophic failures of structures and loss of life. Over the last many years, a large amount of research has been devoted into developing effective earthquake resistant systems in order to raise the seismic performance level of structures. The purpose of this study is to propose a new damping system, which realize not only increasing seismic performance but also easy repairing after an earthquake. The proposed damping system is slit in the bottom of wall with damping devices installed in the slit horizontally aiming to dissipate energy during earthquakes. Cyclic loading tests were conducted to investigate hysteretic behavior and energy dissipation capacity. Test results show that the proposed systems exhibit a stable hysteretic response and the energy dissipation in this system is concentrated on the damping devices.

A Study on the Characteristics of Mammoth Vibro Tamper by Numerical Analysis (대형진동햄머다짐의 수치해석적 연구)

  • 박양수;박인준;김수일
    • Journal of the Korean Geotechnical Society
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    • v.16 no.5
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    • pp.45-54
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    • 2000
  • 경험적으로 방법에 의존해온 대형 진동햄머다짐의 영향심도를 평가하고자 수치해석적인 기법을 사용하였다. 수치해석적인 기법을 사용하였다. 수치해석에 사용한 프로그램은 범용 유한요소 해석프로그램인 ABAQUS이며, 인천 신공항 매립지에서 시험 시공한 대형 진동햄머다짐의 자료와 수치해석한 결과의 비교를 통해 검증하였다. 수치해성에 사용한 물성은 현장시험과 실내시험을통해 구하였으며 영향깊이는 지반이 동적 하중에 변형할 때 소산하는 소성변형율에너지량의 분포를 판정하였다. 수치해석결과 소성변형율에너지 소산량의 시간에 따른 변화로부터 다짐의 영향깊이 및 수평영향거리를 추정할 수 있었다. 소성변형율에너지 수렴시의 외부에너지를 Menard의 경험식에 적용할 경우 영향깊이를 판정할 수 있음을 알았다. 따라서 Menardtlr으로부터 영향깊이를 다짐하는데 필요한 최소한의 에너지를 구할수 있을 것으로 판단된다.

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On the Damping of A Shock Absorption Device Composed of Disk Spring Stacks (디스크 스프링의 적층 배열에 따른 완충장치의 감쇠에 관한 연구)

  • Choi, Myung-Jin;Ko, Seok-Hoon
    • Journal of the Korean Institute of Gas
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    • v.12 no.4
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    • pp.46-51
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    • 2008
  • The damping of a shock absorption device composed of nonlinear disk spring stacks and rubber rings was investigated. Friction forces of rubber rings and hysteresis of disk springs were obtained experimentally. The hysteresis curves of several types of disk spring stacks were approximated, from which the energy dissipated was estimated. Based upon the friction force and the energy dissipated, 4 damping models were presented and shock responses of the damping models were investigated. The hysteresis of disk spring is more meaningful than the friction of the rubber ring for the damping. For practical use, equivalent viscous damping model for total energy dissipated per cycle was suggested.

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A Study on Forced Vibration Tests on a Structure with Stud Type of Vibration Control Damper (스터드형 진동제어 강재댐퍼가 장착된 3층 강구조 골조의 강제진동실험에 관한 연구)

  • Lee, Seung-Jae
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.2
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    • pp.115-121
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    • 2006
  • In recent years vibration control damper made of low yield point steel is expected to play an important role in controlling structural vibration induced earthquake and wind. But their dynamic characteristics and energy dissipation effects on the whole structure model are not clarified. In this paper, firstly, we presents the results of cyclic tests on low yield steel dampers. Secondly, forced vibration tests on existence three stories steel structure model with low yield point steel dampers are presented. Lastly, it is estimated energy amount which is dissipated through the hysteresis dampers by using two types of analytical models, hysteresis model and equivalent linear model.

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Nonlinear Analysis and Design of Rectangular Damper (직사각형 댐퍼의 비선형 해석 및 설계)

  • Eom, Seung Hyeon;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4
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    • pp.447-456
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    • 2003
  • In this study, the proper shape of dampers was determined when the outside frame formed a rectangle. The proper shape of dampers is rectangular, having the same ratio as the outside frame. The design was based on the impact energy dissipated by the seismic performance of the mainly rectangular dampers. This study sought to compare both strength and energy dissipation between nonlinear analysis data and experimental data through load-displacement curves. The use of the ANSYS FEM software was suggested to analyze the nonlinear behavior of rectangular dampers subjected to cyclic loading. The target of this study was to determine what shape was efficient for rectangular tensile brace dampers. The safety of the developed rectangular dampers was also checked for better fabrication.