• Title, Summary, Keyword: Resonance

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Characteristic of wireless power transmission S-Parameter for a superconductor coil

  • Jeong, In-Sung;Jung, Byung-Ik;Choi, Hyo-Sang
    • Progress in Superconductivity and Cryogenics
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    • v.17 no.1
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    • pp.36-39
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    • 2015
  • Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency.

Analysis of the Effects According to Changes in Impedance and Electrical Equivalent Circuit Modeling of a SONAR Transducer Considering Dual Resonance (이중 공진을 고려한 소나 트랜스듀서의 전기적 등가회로 모델링 및 임피던스 변동에 따른 효과 분석)

  • Mok, Hyung-Soo;Choi, Jae-Hyuk;Han, Soo-Hee;Park, Sang-Zoon;Kim, Sung-Joo;Heo, Jun-Ki
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.144-151
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    • 2015
  • The present study proposes a method for modeling a SONAR transducer with dual resonance. The Butterworth van-Dyke (BVD) model, a conventional SONAR transducer modeling method, can model only one resonance point. Hence, to address its disadvantage and to model the dual resonance, a dual resonance BVD model consisting of two serial BVD models is proposed. The two BVD models are connected in a series, and each simulate resonance at low frequency and high frequency, which allows the modeling of two resonance points. Eight elements compose the equivalent circuit by connecting the BVD models in a series, which is twice as great as that of the existing BVD model. The element value of the dual resonance BVD model is extracted by using the particle swarm optimization method. Analysis was also performed to identify the effects of changes in the value of elements that compose the equivalent circuit on the impedance characteristics of the equivalent circuit through simulation in which element values varied.

Effects of Acoustic Resonance and Volute Geometry on Phase Resonance in a Centrifugal Fan

  • Tsujimoto, Yoshinobu;Tanaka, Hiroshi;Doerfler, Peter;Yonezawa, Koichi;Suzuki, Takayuki;Makikawa, Keisuke
    • International Journal of Fluid Machinery and Systems
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    • v.6 no.2
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    • pp.75-86
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    • 2013
  • The effects of acoustic resonance and volute geometry on phase resonance are studied theoretically and experimentally using a centrifugal fan. One dimensional theoretical model is developed taking account of the reflection from the discharge pipe end. It was found that the phase resonance occurs, even with the effects of acoustic resonance, when the rotational speed of rotor-stator interaction pattern agrees with the sound velocity. This was confirmed by experiments with and without a silencer at the discharge pipe exit. The pressure wave measurements showed that there are certain effects of the cross-sectional area change of the volute which is neglected in the one dimensional model. To clarify the effects of area change, experiments were carried out by using a ring volute with a constant area. It was demonstrated that the phase resonance occurs for both interaction modes travelling towards/away from the volute. The amplitude of travelling wave grows towards the volute exit for the modes rotating towards the volute exit, in the same direction as the impeller. However, a standing wave is developed in the volute for the modes rotating away from the volute exit in the opposite direction as the impeller, as a result of the interaction of a growing wave while travelling towards the tongue and a reflected wave away from the tongue.

Efficiency evaluation and characteristics of receiver coil under different inserted resonance coils in wireless power charging system for MAGLEV

  • Chung, Yoon Do;Jeon, Haeryong
    • Progress in Superconductivity and Cryogenics
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    • v.20 no.1
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    • pp.23-27
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    • 2018
  • As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power. From this reason, the WPT systems have started to be applied to the wireless charging for various power applications such as train, underwater ship, electric vehicle. This study aims for the effect and characteristics of different inserted resonance coil between Tx and Rx coils for charging system of superconducting magnetic levitation (MAGLEV) train. The transfer efficiency and effect are evaluated with helix type, rectangular type copper resonance coil, and HTS resonance coil under bulb and HTS magnet load, respectively. The input power is adapted with radio frequency (RF) power of 370 kHz below 500 W.

A Study on the Pressure Resonance with Combustion Chamber Geometry for a Spark Ignition Engine (스파크 점화기관의 연소실 형상에 따른 공진현상 해석에 관한 연구)

  • Park, Gyeong-Seok;Jang, Seok-Hyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.12
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    • pp.1905-1910
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    • 2001
  • Pressure resonance frequency that is caused in the combustion chamber can be interpreted by acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(finite element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To match the experimental results, the speed of sound that satisfies Draper's equation is selected 13% higher than the value for pent-roof type combustion chamber.

Structural Studies on IRES 4-2 Domain of Foot-and-mouth Disease Virus

  • Kim, Young-Mee;Yoo, Jun-Seok;Cheong, Hae-Kap;Lee, Chul-Hyun;Cheong, Chae-Joon
    • Journal of the Korean Magnetic Resonance Society
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    • v.7 no.2
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    • pp.89-97
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    • 2003
  • Foot-and-mouth disease virus (FMDV) belongs to the aphthovirus genus within the picornavirus which has a single copy of a positive sense RNA. The translation initiation process of FMDV occurs by a cap-independent mechanism directed by a highly structured element (∼435 nt) termed an internal ribosome entry site (IRES). We have designed and prepared FMDV 4-2 RNA (28nt) by in vitro transcription. The 2D NMR data revealed that FMDV 4-2 IRES domain RNA has a flexible loop and bulge conformation. In further study, we need to make an isotope labeled RNA sample and conduct 3D NMR experiments to completely determine the 3D structure. This study may establish a new drug design strategy to treat foot-and mouth disease.

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Analysis of Magnetic Resonance Characteristics and Images of Korean Red Ginseng (홍삼의 자기공명 특성과 영상 분석)

  • 김성민;임종국
    • Journal of Biosystems Engineering
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    • v.28 no.3
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    • pp.253-260
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    • 2003
  • In this study, the feasibility of magnetic resonance techniques for nondestructive internal quality evaluation of Korean red ginseng was examined. Relaxation time constants were measured using various grades of red ginsengs. Solid state magnetic resonance imaging technique was applied to image dried red ginsengs which have low moisture contents (about 13%). A 7 tesla magnetic resonance imaging system operating at a proton resonant frequency of 300 ㎒ was used for acquiring MR images of dried Korean red ginseng. The comparison test of cross cut digital images and magnetic resonance images of heaven grade, good grade with cavity inside, and good grade with white part inside red ginseng suggested the feasibility of the internal quality evaluation of Korean red ginsengs using MRI techniques. A good grade red ginseng included abnormal tissues such as cavities or white parts inside was observed by the signal intensity of MR image based on magnetic resonance properties of proton nucleus. Analysis on an one dimensional profile of acquired MR image of Korean red ginseng showed easy discrimination of normal and abnormal tissues. MR techniques suggested ways to detect internal defects of red ginsengs effectively.

Analysis of the Efficiency According to Resonant Repeater Application in Magnetic Resonant Wireless Power Transfer System (자기공진방식의 무선전력전송 시스템에서 공진 중계기 적용 여부에 따른 전력전송 효율 분석)

  • Baek, Seung-Myung;Kim, Dong-Eun;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.67 no.4
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    • pp.221-226
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    • 2018
  • In this paper, the power transfer efficiency analysis based on the resonant repeater in a magnetic resonance wireless power transfer system is proposed. The efficiency of the magnetic resonance method was verified by comparing the general frequency with the resonance frequency. The resonance repeater was arranged to increase the efficiency and increase the transfer distance. When using resonant repeaters, the maximum efficiency increase is about 36.23[%] and the transfer distance was extended to more than 20[cm]. Through this study, confirmed the effect of using resonance repeaters in wireless power transfer system. As a result, it can be expected that the overall technology related to wireless power transfer system will be more valuable for energy-IT technology.

A Study on the Presure Resonance with Combustion Chamber Geometry for a Spark Ignition Engine (스파크 점화기관의 연소실 형상에 따른 공진현상 해석에 관한 연구)

  • Park, Kyoung-Suk;Jang, Seok-Hyung
    • Proceedings of the KSME Conference
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    • pp.890-895
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    • 2001
  • Pressure resonance frequency that is caused in the combustion chamber can be interpreted to acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(fine element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The reduce error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To make the experimental results equal we could know that the speed of sound that satisfies Draper's equation was selected 13% higher than all the pent-roof type combustion considered.

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Nondestructive Inspection Method of Composite Laminated Plates by Holographic Interferometry (홀로그래피 간섭계를 이용한 복합적층판의 결함측정)

  • 김석중;김재형;박현철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3202-3218
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    • 1994
  • Mode shapes and natural frequencies of vibrating laminated composite plates are taken using real-time and time-average holographic interferometry. Debonds and delamination in the laminated plates are measured nondestructively. During holographic testing of composite plates, it has been found that the conditions for the local resonance in debonds are strongly dependent on the frequency of excitation. A membrane resonance model was proposed to describe this behavior. Relations between characteristic length according to the size, shape of debonds and membrane resonance frequency are presented. Several experiments were performed to verify the membrane resonance model. The agreements between the predicted excitation frequency and the observed resonance frequency are good. The experimental results show that higher stresses and strains due to local resonance lead to the debond detection.