• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.42-49
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• 2006

In this paper, an efficient piezoelectric passive damper is newly devised to suppress the multi-mode vibration of plates. To construct the passive damper, the piezoelectric materials are utilized as energy transformer, which can transform the mechanical energy to electrical energy. To dissipate the electrical energy transformed from mechanical energy, multiple resonant shunted piezoelectric circuits are applied. The dynamic governing equations of a coupled electro-mechanical piezoelectric with multiple piezoelectric patches and multiple resonant shunted circuits is derived and solved for the one edge clamped plate. The equations of motion of the piezoelectrics and shunted circuits as well as the plate are discretized by finite element method to estimate more exactly the effectiveness of the piezoelectric passive damper. The method to find the optimal location of a piezoelectric is presented to maximize effectiveness for desired modes. The electro-mechanical coupling term becomes important parameter to select the optimal location.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.97-99
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• 2009

Bilateral teleoperation systems, connected to computer networks such as Internet have to deal with the time delay varying depending on factors such as congestion, bandwidth or distance. And the entire system is easy to become unstable due to irregular time delay. Passivity concept has been using as a framework to solve the stability problem in bilateral control of teleoperation. Acontrol scheme for teleoperation systems with varying time delay is proposed based on a passivity concept is proposed in this paper. One approach makinguse of the characteristic impedances is proposed to achieve a passive control. Since passive control does not mean that the system performance will be acceptable, another transmission scheme which focuses on both the passive feature and the acceptable performance is configured for varying time delay in this paper. The tracking performance has been proved through the computer simulation for varying time delay bilateral teleoperation system using Matlab Simulink.

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.152-158
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• 2004

The passive filter is economic and efficient in suppressing harmonics but it may cause resonance problems and its performance is constantly dependent on power system impedance or working conditions of loads. This paper presents the DSP (Digital Signal Processor)-based control system, which automatically controls the passive filter in order to solve these problems. The control system can automatically control the passive filter according to working conditions of loads and measured harmonics, reactive power, power factor and so on. Experimental results in the power system using the 100HP DC motor drive are presented in order to verify the performance of the control system.

• 대한기계학회논문집A
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• 제29권11호
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• pp.1534-1541
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• 2005

Unlike industrial manipulators, the manipulators mounted on service robots are interacting with humans in various aspects. Therefore, safety has been one of the most important design issues. Many compliant robot arms have been introduced for safety. It is known that passive compliance method has faster response and higher reliability than active ones. In this paper, a new safety mechanism based on passive compliance is proposed. Passive mechanical elements, specifically transmission angle of the 4-bar linkage, springs and shock absorbing modules are incorporated into this safety mechanism. This mechanism works only when the robot arm exerts contact force much more than the human pain tolerance. Validity of this mechanism is verified by simulations and experiments. It is shown that the manipulator using this mechanism provides higher performance and safety than those using other passive compliance mechanisms or active methods.

• Smart Structures and Systems
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• 제7권5호
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• pp.417-432
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• 2011

The present paper is devoted to vibration canceling and shape control of piezoelastic slender beams. Taking into account the presence of electric networks, an extended electromechanically coupled Bernoulli-Euler beam theory for passive piezoelectric composite structures is shortly introduced in the first part of our contribution. The second part of the paper deals with the concept of passive shape control of beams using shaped piezoelectric layers and tuned inductive networks. It is shown that an impedance matching and a shaping condition must be fulfilled in order to perfectly cancel vibrations due to an arbitrary harmonic load for a specific frequency. As a main result of the present paper, the correctness of the theory of passive shape control is demonstrated for a harmonically excited piezoelelastic cantilever by a finite element calculation based on one-dimensional Bernoulli-Euler beam elements, as well as by the commercial finite element code of ANSYS using three-dimensional solid elements. Finally, an outlook for the practical importance of the passive shape control concept is given: It is shown that harmonic vibrations of a beam with properly shaped layers according to the presented passive shape control theory, which are attached to an resistor-inductive circuit (RL-circuit), can be significantly reduced over a large frequency range compared to a beam with uniformly distributed piezoelectric layers.

• 해양환경안전학회지
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• 제27권1호
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• pp.161-171
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• 2021

본 연구에서는 20,000 톤급 해양플랜트 상부구조물(Topside)의 플로트오버 설치작업을 위해 개발된 수동형 갑판 지지 프레임(Deck support frame)의 구조설계에 대해 다양한 실험계획법을 이용한 최소중량설계와 민감도 평가의 비교연구를 수행하였다. 수동형 갑판 지지 프레임의 주요 구조부재의 두께 치수 변수는 설계인자로 고려하였고, 응답치는 중량과 강도성능으로 선정하였다. 최소중량설계와 민감도 평가의 비교연구에 사용한 실험계획법은 직교배열설계법, Box-Behnken 설계법, 그리고 Latin hypercube 설계법이다. 실험계획법의 설계공간 탐색의 근사화 성능을 평가하기 위해 반응표면법을 각 실험계획법 별로 생성하여 근사화 정확도 특성을 검토하였다. 또한 최소중량설계를 위해 최상 설계안의 결과로 부터 실험계획법의 특성에 따른 수치계산 비용, 중량감소 효과 등을 평가하였다. 수동형 갑판 지지 프레임의 구조설계에 대해 Box-Behnken 설계법이 가장 적합한 설계 결과를 나타내었다.

• 한국유체기계학회 논문집
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• 제19권5호
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• pp.50-60
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• 2016

A design methodology of the modeled test facility to conserve an injection performance of a passive safety injection system is proposed. This safety injection system is composed of a core makeup tank and a safety injection tank. Individual tanks are connected with pressure balance line on the top side and injection line on the bottom side. It is important to conserve the scaled initial injection flow rate and total injection time since this system can be operated by small gravity head without any active pumps. Differential pressure distribution of the injection line induced by the gravity head is determined by the vertical length and elevation of each tank. However, the total injection time is adjustable by the flow resistance coefficient of the injection line. The scaling methodology for the tank and flow resistance coefficient is suggested. A key point of this test facility design is a scaling analysis for the flow resistance coefficient. The scaling analysis proposed on this paper is based on the volume scaling law with the same vertical length to the prototype and can be extended to a model with a reduced vertical length. A set of passive injection test were performed for the tanks with the same volume and the different length. The test results on the initial flow rate and total injection time showed the almost same injection characteristics and they were in good agreement with the design values.

• International Journal of Precision Engineering and Manufacturing
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• 제4권1호
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• pp.37-42
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• 2003

Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping have been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.186-188
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• 2008

The wireless communication revolution has spawned a revival of interest in the design and optimization of radio transceivers. Radio transmit modules continue to shrink in die size and cost, requiring novel approaches for integration of the numerous passive elements of the radio front-end. A 3 dB Wilkinson power divider based on GaAs substrates, for DCS 1710-1880 MHz band was designed and fabricated showing excellent performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
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• pp.64-66
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• 2002

This paper reports the design, modeling, fabrication and measurement of passive microvalves applicable to glaucoma implants. The proposed microvalves consisted of microchannels and chambers. The microchannels had a fixed fluidic resistance and generated a pressure difference. The chamber was located in the middle of the microchannels and acted as a buffer preventing an abrupt pressure change from an external variation of the fluid flow. To find optimum design parameters, six kinds of the microvalves were fabricated and experimented.