• Title/Summary/Keyword: Intermediate frequency

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Extremely high efficiency wireless power transfer system for EV charger (전기자동차 충전을 위한 고효율 무선전력전송 시스템)

  • Moon, SangCheol;Moon, Gun-Woo
    • Proceedings of the KIPE Conference
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    • 2015.07a
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    • pp.155-156
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    • 2015
  • This paper proposes a high efficiency wireless power transfer system with an asymmetric 4-coil resonator. It presents a theoretical analysis, an optimal design method, and experimental results. In the proposed asymmetric 4-coil system, the primary side consists of a source coil and two transmitter coils which are called intermediate coils, and in the secondary side, a load coil serves as a receiver coil. In the primary side, two intermediate coils boost the apparent coupling coefficient at around the operating frequency. Because of this double boosting effect, the system with an asymmetric 4-coil resonator has a higher efficiency than the conventional symmetric 4-coil system. The prototype operates at 90 kHz ofswitching frequency and has 200 mm of the power transmission distance between the primary side and the secondary side. An AC-DC overall system efficiency of 96.56% has been achieved at 3.3 kW of output power.

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Planar Active Rectrodirective Array With Subharmonic Phase Conjugation Mixers

  • Kim Gi-Rae;Park Ji-Yong
    • Journal of information and communication convergence engineering
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    • v.2 no.3
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    • pp.153-156
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    • 2004
  • A planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is proposed. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. Receiving, transmitting, local oscillator, and intermediate frequencies are 5.79, 5.81, 2.9 GHz, and 10 MHz. Monostatic RCS and Bistatic RCS measurements at source locations of $0^{\circ},\;-20^{\circ},\;and\;28^{\circ}$ show good agreement with the calculated data.

A New PTS OFDM Scheme with Low Complexity for PAPR Reduction (OFDM 통신 시스템에서 PAPR을 줄이기 위한 적은 계산 복잡도를 갖는 PTS 방법)

  • Lim Dae-Woon;Heo Seok-Joong;No Jong-Seon;Chung Ha-Bong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.9C
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    • pp.914-920
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    • 2006
  • In this paper, we introduce a new partial transmit sequence (PTS) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. In the proposed scheme, $2^n$-point inverse fast Fourier transform (IFFT) is divided into two parts. An input symbol sequence is partially transformed using the first l stages of IFFT into an intermediate signal sequence and the intermediate signal sequence is partitioned into a number of intermediate signal subsequences. Then, the remaining n - l stages of IFFT are applied to each of the intermediate signal subsequences and the resulting signal subsequences are summed after being multiplied by each member of a set of W rotating vectors to yield W distinct OFDM signal sequences. The one with the lowest peak to average power ratio (PAPR) among these OFDM signal sequences is selected for transmission. The new PTS OFDM scheme reduces the computational complexity while it shows almost the same performance of PAPR reduction as that of the conventional PTS OFDM scheme.

A Study on the Wireless Power Transfer System using Magnetic Resonance at the 1[MHz] Frequency Band (1[MHz] 대역의 자계 공명을 이용한 무선 전력 전송 장치에 관한 연구)

  • Park, Jeong-Heum
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.1
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    • pp.75-81
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    • 2012
  • In this paper, the wireless power transfer system using the magnetic resonance was designed, analyzed by circuit analysis methode and the calculated transfer function was compared with the measured one. The self-resonant coil was made up of the commonly used capacitor which had the lumped capacitance and it enabled the stable magnetic resonance not to be affected by the circumstance. The transmission efficiency of this system was 70[%] at the 15[cm] between the transmission and receiving coil and the measured transfer function was similar to the calculated one, which means the circuit analysis methode is valid in this system. When the intermediate coils were added between the transmission and receiving coil, the transmission efficiency was increased, which produced the increase of transfer distance. In the case of the five intermediate coils adding, the 35[%] transmission efficiency was achived at the 90[cm] distance.

Frequency Characteristics of Shallow Seismic Reflection Data - Dogye, Samchuck, Kangwon (천부 탄성파 반사법 자료의 주파수 특성 - 강원도 삼척시 도계지역)

  • Ko, Kwang-Beom;Lee, Doo-Sung
    • Geophysics and Geophysical Exploration
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    • v.3 no.1
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    • pp.19-24
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    • 2000
  • Seismic reflection data was obtained by using 28 and 100 Hz geophones at the ground subsidence sites in an old coal mine area. Frequency spectrum of the geophone analyzed with offset revealed that 1) In the near offset ($1\~10m$), the signals in the 100 Hz geophone data contains higher frequency components (up to 300 Hz) than that of the 28 Hz (<200 Hz), 2) In the intermediate offset ($11\~39m$), although the 28 Hz geophone data showed very similar frequency characteristics as the near offset data, the 100Hz geophone data seemed to be contaminated by noise at high frequency zone (>200 Hz). In the far offset ($\geq40\;m$), the signals in both the 28 and 100 Hz geophone data are attenuated to noise level at high frequency Bone more than 150 Hz.

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A Study on Optimal Design of Panel Shape of a Body Structure for Reduction of Interior Noise

  • Kim, Hyo-Sig;Yoon, Seong-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.694-698
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    • 2006
  • This paper presents an optimal design process using beads on a body panel to improve interior noise of a passenger vehicle. Except modification of structural members, it is difficult to find effective countermeasures that can work for the intermediate frequency range from 100 Hz to 300 Hz which lies between the booming and low medium frequency. In this study, it is a major goal to find additional counter-measures for this intermediate frequency range by performing optimal design of beads on body panels. The proposed method for design optimization consists of 4 sub-steps, that is, a) problem definition, b) cause analysis, c) countermeasure development and d) validation. The objective function is minimization of interior noise level. The major design variables are the geometrical shape of a bead and combination of beads on the critical panels. Sensitivity analysis and optimization are performed according to the predefined process for an optimal design. It is verified that the proposed design decreases the level of noise transfer function above 5 dB.

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Binary Black Hole Inspirals and GW detection in 0.1-10 Hz

  • Bae, Yeong-Bok;Ahn, Sang-Hyeon;Kang, Gungwon;Kim, Chunglee;Kim, Whansun;Oh, John J.;Oh, Sang Hoon;Park, Chan;Son, Edwin J.;Lee, Yong Ho
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.53.3-53.3
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    • 2017
  • The pilot study of SLGT (Superconducting Low-frequency Gravitational-wave Telescope) is being performed by KKN (KASI-KISTI-NIMS) collaboration. In this presentation, we discuss prospectives of detecting GWs in the low-frequency band (0.1-10 Hz), which is a target frequency band of SLGT, but can be hardly observed by advanced LIGO. IMBHBs (Intermediate Mass Black Hole Binaries) and IMRIs (Intermediate Mass Ratio Inspirals) with total masses of O(1000) up to O(10,000) solar masses are most probable sources between 0.1-10 Hz. We estimate horizon distances and signal to noise ratios of IMBHBs and IMRIs for different SLGT design sensitivities. Based on our calculations, detection rates for IMBHBs and IMRIs with SLGT will be discussed.

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Simple Method of Vibration Analysis of Three Span Continuous Reinforced Concrete Bridge with Elastic Intermediate Support (탄성지지된 3경간 철근콘크리트 교량의 간단한 진동해석법)

  • Kim, Duk-Hyun;Han, Bong-Koo
    • Composites Research
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    • v.17 no.3
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    • pp.23-28
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    • 2004
  • A method of calculating the natural frequency corresponding to the first mode of vibration of beams and tower structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the three span continuous reinforced concrete bridge with elastic intermediate supports is presented. Such bridge represents either concrete or sandwich type three span bridge on polymeric supports for passive control or on actuators for active control. The concrete slab is considered as a special orthotropic plate. Any method may be used to obtain the deflection influence surfaces needed for this vibration analysis. Finite difference method is used for this purpose, in this paper, The influence of the modulus of the foundation and $D_{22}$, $D_{12}$, $D_{66}$ stiffnesses on the natural frequency is thoroughly studied.

Electrical Characteristics of 3rd Overtone Mode Energy-trapped High Frequency Filter using PbTiO3 System Ceramics (PbTiO3계 세라믹스를 이용한 3차 진동모드 에너지 트랩형 고주파필터의 전기적 특성)

  • 오동언;류주현;윤현상;박창엽;이수호;김종선;정회승
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.7
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    • pp.593-598
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    • 2003
  • In this paper, 3rd overtone mode energy-trapped filter using modified PbTiO$_3$ system ceramics was manufactured to apply for intermediate frequency(IF) SMD type fillet with splitted electrode and gap size. To investigate the effects of splitted electrode and gap size on filter characteristics of 3rd overtone mode energy-trapped filter, ceramic wafers were fabricated by etching splitted rectangular electrode size(b$\times$d) of b=0.4, 0.6, 0.8, 1mm, d=0.3, 0.4, 0.5, 0.6mm and gap size(c) c=0.2, 0.3, 0.4, 0.6mm, respectively. And then, SMD type ceramic filter were fabricated with the size of 3.7$\times$3.1$\textrm{mm}^2$. SMD type ceramic filter with the size of b=0.8mm, d=0.4mm and gap(c)=0.4mm, which showed insertion loss of 2.951dB, 3dB bandwidth of 54.7kHz and 20dB stop bandwidth of 129.27kHz, was suitable for IF bandpass filter application.

Bearing and Rotordynamic Performance Analysis of a 250 kW Reduction Gear System (250 kW급 초임계 CO2 발전용 감속기의 유체 윤활 베어링 및 회전체 동역학 특성 해석)

  • Lee, Donghyun;Kim, Byungok
    • Tribology and Lubricants
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    • v.32 no.4
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    • pp.107-112
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    • 2016
  • This paper presents a rotordynamic analysis of the reduction gear system applied to the 250 kW super critical CO2 cycle. The reduction gear system consists of an input shaft, intermediate shaft, and output shaft. Because of the high rotating speed of the input shaft, we install tilting pad bearings, rolloer bearings support the intermediate and output shafts. To predict the tilting pad bearing performance, we calculate the applied loads to the tilting pad bearings by considering the reaction forces from the gear. In the rotordynamic analysis, gear mesh stiffness results in a coupling effect between the lateral and torsional vibrations. The predicted Campbell diagram shows that there is not a critical speed lower than the rated speed of 30,000 rpm of the input shaft. The predicted modes on the critical speeds are the combined bending modes of the intermediate and output shaft, and the lateral vibrations dominate when compared to the torsional vibrations. The damped natural frequency does not strongly depend on the rotating speeds, owing to the relatively low rotating speed of the intermediate and output shaft and constant stiffness of the roller bearing. In addition, the logarithmic decrements of all the modes are positive; therefore all modes are stable.