• Title, Summary, Keyword: Resonant frequency

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Defect Evaluation of Optical Lens by Resonant Ultrasound Spectroscopy (공명초음파분광법을 활용한 광학기기용 렌즈의 결함평가)

  • 김성훈;백경윤;김영남;양인영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1491-1495
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    • 2004
  • In this paper, resonant ultrasound spectroscopy(RUS) was used to determine the natural frequency of a spherical and a aspherical lens. The objective of the paper is to evaluate defect and shape error by using nondestructive evaluation method with Resonant Ultrasound Spectroscopy(RUS). The principle of RUS is that the mechanical resonant frequency of the materials depends on density, and the coefficient of elasticity. We evaluated existence of flaws through comparison with resonant frequency of a spherical and a aspherical lens. The spherical glass lenses were made of BK-7 glass, one's diameter in 2mm and 5mm. The polished spherical glass lenses had no deflection or a deflection below 2.0${\mu}{\textrm}{m}$. Also, The aspherical lens were made of same material and ones diameter in 7mm and thickness in 3.4mm. In the experiment, we were performed to investigate relationship between frequency measuring parameter($\beta$) and mass of each specimens. The difference between resonant frequency and mode of aspherical glass lens which has no defect was distinguished from aspherical glass lens which has some defects.

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A Novel Control Scheme for T-Type Three-Level SSG Converters Using Adaptive PR Controller with a Variable Frequency Resonant PLL

  • Lin, Zhenjun;Huang, Shenghua;Wan, Shanming
    • Journal of Power Electronics
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    • v.16 no.3
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    • pp.1176-1189
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    • 2016
  • In this paper, a novel quasi-direct power control (Q-DPC) scheme based on a resonant frequency adaptive proportional-resonant (PR) current controller with a variable frequency resonant phase locked loop (RPLL) is proposed, which can achieve a fast power response with a unity power factor. It can also adapt to variations of the generator frequency in T-type Three-level shaft synchronous generator (SSG) converters. The PR controller under the static α-β frame is designed to track ac signals and to avert the strong cross coupling under the rotating d-q frame. The fundamental frequency can be precisely acquired by a RPLL from the generator terminal voltage which is distorted by harmonics. Thus, the resonant frequency of the PR controller can be confirmed exactly with optimized performance. Based on an instantaneous power balance, the load power feed-forward is added to the power command to improve the anti-disturbance performance of the dc-link. Simulations based on MATLAB/Simulink and experimental results obtained from a 75kW prototype validate the correctness and effectiveness of the proposed control scheme.

Fabrication and Frequency Agile of Microstrip Antennas Using Y-cut $LiNbo_3$, Quartz and FR-4 Substrates. (Y-cut $LiNbo_3$, Quartz, FR-4 기판을 이용한 마이크로스트립 안테나의 제작과 공진주파수 이동에 관한 연구.)

  • Lee, Ki-Se;Lee, Kyu-Il;Kang, Hyun-Il;Song, Joon-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.116-120
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    • 2004
  • In this paper, we proposed a method to shift the resonant frequency by applying the electric field to microstrip patch antenna using piezoelectric substrates. We fabricated microstrip patch antenna using Y-cut LiNbO3, Quartz and FR-4 substrates. We designed and simulated the microstrip antennas by Ensemble V 7.0 of the simulation too1. We observed the resonant frequency by DC applied electric field in a microstrip patch antenna. When the electric field was 300 V/mm, the resonant frequency agile of Y-cut LiNbO3 microstrip patch antennas were 29 MHz. When the electric field was 400 V/mm, the frequency agile of X-cut, Y-cut and Z-cut quartz microstrip patch antennas were 55.2 MHz, 34.2 MHz and 28.0 MHz, respectively. However, when the electric field was 400 V/mm, the resonant frequency of FR-4 microstrip patch antenna does not changed. It was shown that the resonant frequency agile of Y-cut and Z-cut quartz microstrip patch antennas are due to piezoelectric phenomenon not to be permittivity.

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Development of the Ultrasonic Sensor for Gas Flowmeter (기체유량계용 초음파 센서 개발)

  • Hong, Jae-Il;Lee, Sang-Cheol
    • Proceedings of the KIEE Conference
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    • pp.131-134
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    • 2002
  • In this paper, the ultrasonic sensor for gas flowmeter was simulated, fabricated and measured with assembly step and piezoelectric vibrator layers. The simulated resonant frequency and the measured resonant frequency were similar except sensor 2. The simulated resonant frequency of sensor 3 was 48 kHz and the measured resonant frequency of sensor 3 was 45.2 kHz. From the results, the ultrasonic sensor for flowmeter could be designed and expected without fabrication.

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Phase Control Loop Design based on Second Order PLL Loop Filter for Solid Type High Q-factor Resonant Gyroscope (고체형 정밀 공진 자이로스코프를 위한 이차 PLL 루프필터 기반 위상제어루프 설계)

  • Park, Sang-Jun;Yong, Ki-Ryeok;Lee, Young-Jae;Sung, Sang-Kyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.6
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    • pp.546-554
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    • 2012
  • This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

Quasi-Resonant PWM Converter Controlled by Constant Frequency (일정한 주파수로 제어되는 쿼지 공진형 PWM 컨버터)

  • Joung, Gyubum
    • Journal of Satellite, Information and Communications
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    • v.12 no.2
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    • pp.28-32
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    • 2017
  • In this paper, a quasi-resonant PWM converter, which is controlled by constant frequency, has been suggested. As quasi-resonant converter, the switches of the suggested converter has soft switching characteristics, which can operate to high frequency with high efficiency. Comparing with varied controlled frequency of quasi-resonant converter for controlling output voltage, the suggested converter has advantages which optimize filter and EMI filter design at constant switching frequency. The converter has been analyzed by switch mode analysis which verified soft switching operation. Also, the PWM operation and characteristics of the converter are verified by simulation and experiment of 100 kHz DC-DC converter.

A Switchable Microstrip Patch Antenna for Dual Frequency Operation

  • Sung, Young-Je
    • ETRI Journal
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    • v.30 no.4
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    • pp.603-605
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    • 2008
  • A novel design for equilateral-triangular microstrip antennas with switchable resonant frequency is proposed. For dual-frequency operation, the proposed design is achieved by loading a pair of slits in the triangular patch, and two PIN diodes are utilized to switch the slits on or off. By increasing the length of the slits, the lower resonant frequency can be varied in the range from 1.22 GHz to 1.72 GHz whereas the upper resonant frequency remains unchanged.

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The Evaluation on the frequency Characteristics of the Optical Glass Lens by Resonant Ultrasound Spectroscopy (RUS법에 의한 광학기기용 렌즈의 주파수 특성평가)

  • Yang, In-Young;Kim, Seung-Hoon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.2
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    • pp.127-132
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    • 2005
  • The optical glass lens is required high dimensional precision such as the lack of defect. In this paper, we examined the detectable defect by using the resonant ultrasound spectroscopy(RUS). The RUS is the measurement system which is to excite the specimen and to inspect the differences of resonant frequency pattern between acceptable specimen and specimen which has some defects. In this paper, for nondestructive evaluation by using RUS, we measured the resonant frequency of each specimen which is spherical and aspherical glass lens. With the results, we knew the polishing processing degree of spherical glass lens by the measured resonant frequency and could evaluate the characteristic of aspherical glass lens about some flaws.

Optimum Design of Micro-Cantilever Sensor for measuring CO gas (CO 가스측정을 위한 마이크로 캔틸레버 센서의 최적화 설계)

  • Son, H.J.;Na, D.S.;Peak, K.K.;Park, B.H.;Kwon, K.H.;Nahm, S.;Ju, B.K.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.412-413
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    • 2005
  • This paper describes resonant frequency of the structural behavior of micro-cantilever beam simulated by FEM (Finite Element Method). The resonant characteristics and the sensitivity of cantilever-shaped SOI resonant were measured for the application of chemical sensor. The resonant frequency of the fabricated micro-cantilever system was found to be 5.59kHz when the size of cantilever is $500{\mu}m$ long, $100{\mu}m$ wide and $1{\mu}m$ thick. Generation of resonant frequency measured by Modal Analysis is resulted in length of cantilever. The length was found to be a dominant factor for the selection of required resonant frequency range. On the other side, the width had influenced very little on either the magnitude of resonant frequency or the sensitivity.

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