• Title/Summary/Keyword: Electromagnetic interference

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Improvement of Field Uniformity in a Reverberation Chamber with Various Numbers of a 2D CRD (2D CRD 수에 따른 전자파 잔향실 내의 필드 균일성 개선)

  • Kim, Jin-Bok;Rhee, Joong-Geun;Kim, Jung-Hoon;Rhee, Eu-Gene
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.4
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    • pp.18-24
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    • 2010
  • This paper presents the improvement of the field uniformity in a reverberation chamber which can be substitute an anechoic chamber for the electromagnetic interference (EMI) and immunity test. Nowadays, there are many EMI issues due to the increasing use of wireless local area network (LAN), digital multimedia broadcasting (DMB), and mobile internet. With this reason, this paper studied the field characteristics in a reverberation chamber for 2.3 GHz band. In this paper, the finite difference time domain (FDTD) method is used to analyze the field characteristics in a reverberation chamber. To improve the field uniformity in the reverberation chamber, this paper adopted a 2D cubical residue diffuser (CRD) with varying the disposition and number of CRD. For each case, the tolerance and standard deviation of the electric field strength are evaluated. In comparison with the reverberation chamber without any CRD, the reverberation chamber with two CRDs showed improved results; 1.98 dB improvement in standard deviation and 3.6 dB improvement in tolerance.

A Study on the Analysis of Broadband Direction finding Antenna on Aircraft (항공기 탑재된 광대역 방향 탐지용 안테나 분석 연구)

  • Baek, Jong-Gyun;Ji, Sung-Hwan;Mun, Byeonggwi;Lee, Kyung-Won;Kim, Dong-Gyu;Lee, Wang-Yong
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.5
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    • pp.89-95
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    • 2018
  • In this paper, we analyze the antenna performance changes caused by the aircraft structure, diffraction and reflection, when the direction finding antenna used in the aircraft is mounted on the aircraft. Direction finding antenna is an antenna that receives radar threat signal in the direction finding device of aircraft electronic warfare system. Recently, because various antenna are mounted on an aircraft, various analyzes such as antenna performance and interference analysis are required. Therefore, the electromagnetic analysis was carried out by installing a broadband direction finding antenna with 50% bandwidth on simulated aircraft, and the direction finding performance was analyzed by comparing the single antenna performance with the performance mounted on the aircraft. The analyzed direction finding accuracy was $6.47^{\circ}$ RMS and predicted to be suitable as an antenna for aircraft direction finding antenna.

Totem-pole Bridgeless Boost PFC Converter Based on GaN FETs (GaN FET을 이용한 토템폴 구조의 브리지리스 부스트 PFC 컨버터)

  • Jang, Paul;Kang, Sang-Woo;Cho, Bo-Hyung;Kim, Jin-Han;Seo, Han-Sol;Park, Hyun-Soo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.3
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    • pp.214-222
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    • 2015
  • The superiority of gallium nitride FET (GaN FET) over silicon MOSFET is examined in this paper. One of the outstanding features of GaN FET is low reverse-recovery charge, which enables continuous conduction mode operation of totem-pole bridgeless boost power factor correction (PFC) circuit. Among many bridgeless topologies, totem-pole bridgeless shows high efficiency and low conducted electromagnetic interference performance, with low cost and simple control scheme. The operation principle, control scheme, and circuit implementation of the proposed topology are provided. The converter is driven in two-module interleaved topology to operate at a power level of 5.5 kW, whereas phase-shedding control is adopted for light load efficiency improvement. Negative bias circuit is used in gate drivers to avoid the shoot-through induced by high speed switching. The superiority of GaN FET is verified by constructing a 5.5 kW prototype of two-module interleaved totem-pole bridgeless boost PFC converter. The experiment results show the highest efficiency of 98.7% at 1.6 kW load and an efficiency of 97.7% at the rated load.

Design of Wideband Facility Power-line EMI filter (광대역 설비용 전원선 EMI 필터의 설계)

  • Chung, Se-Kyo;Lim, Jeong-Gyu;Kim, Mu-Hyun;Kang, Byoung-Kuk
    • The Transactions of the Korean Institute of Power Electronics
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    • v.14 no.6
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    • pp.440-448
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    • 2009
  • Facility power-line electromagnetic interference (EMI) filters are used to provide radio frequency(RF) isolation between dedicated power distribution services and noise sensitive local power distribution systems. This type of EMI filters generally needs a high current capacity and, in some special applications, a high insertion loss of a minimum 100dB from 14kHz through 10GHz per MIL-STD 220 is required. This paper deals with an analysis and design of a wideband facility power-line EMI filter with the above requirements. The characteristics of the inductor and capacitor at high frequencies are investigated. The characteristics and design method of the facility EMI filter with a high order LC network are also presented. The prototype filter is finally implemented and its performance is verified from the experimental results.

The Controller Design of a 2.4MJ Pulse Power Supply for a Electro-Thermal-Chemical Gun (전열화학포용 2.4MJ 펄스 파워 전원의 제어기 설계)

  • Kim, Jong-Soo;Jin, Y.S.;Lee, H.S.;Rim, Geun-Hie;Kim, J.S.
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.12
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    • pp.511-517
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    • 2006
  • The key issues in high power, high energy applications such as electromagnetic launchers include safety, reliability, flexibility, efficiency, compactness, and cost. To explore some of the issues, a control scheme for a large current wave-forming was designed, built and experimentally verified using a 2.4MJ pulse power system (PPS). The PPS was made up of eight capacitors bank unit, each containing six capacitors connected in parallel. Therefore there were 48 capacitors in total, with ratings of 22kV and 50kJ each. Each unit is charged through a charging switch that is operated by air pressure. For discharging each unit has a triggered vacuum switch (TVS) with ratings of 200kA and 250kV. Hence, flexibility of a large current wave-forming can be obtained by controlling the charging voltage and the discharging times. The whole control system includes a personal computer(PC), RS232 and RS485 pseudo converter, electric/optical signal converters and eight 80C196KC micro-controller based capacitor-bank module(CBM) controllers. Hence, the PC based controller can set the capacitor charging voltages and the TVS trigger timings of each CBM controller for the current wave-forming. It also monitors and records the system status data. We illustrated that our control scheme was able to generate the large current pulse flexibly and safely by experiments. The our control scheme minimize the use of optical cables without reducing EMI noise immunity and reliability, this is resulting in cost reduction. Also, the reliability was increased by isolating ground doubly, it reduced drastically the interference of the large voltage pulse induced by the large current pulse. This paper contains the complete control scheme and details of each subsystem unit.

Impact of the human body in wireless propagation of medical implants for tumor detection

  • Morocho-Cayamcela, Manuel Eugenio;Kim, Myung-Sik;Lim, Wansu
    • Journal of Internet Computing and Services
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    • v.21 no.2
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    • pp.19-26
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    • 2020
  • This paper analyses the feasibility of using implantable antennas to detect and monitor tumors. We analyze this setting according to the wireless propagation loss and signal fading produced by human bodies and their environment in an indoor scenario. The study is based on the ITU-R propagation recommendations and prediction models for the planning of indoor radio communication systems and radio local area networks in the frequency range of 300 MHz to 100 GHz. We conduct primary estimations on 915 MHz and 2.4 GHz operating frequencies. The path loss presented in most short-range wireless implant devices does not take into account the human body as a channel itself, which causes additional losses to wireless designs. In this paper, we examine the propagation through the human body, including losses taken from bones, muscles, fat, and clothes, which results in a more accurate characterization and estimation of the channel. The results obtained from our simulation indicates a variation of the return loss of the spiral antenna when a tumor is located near the implant. This knowledge can be applied in medical detection, and monitoring of early tumors, by analyzing the electromagnetic field behavior of the implant. The tumor was modeled under CST Microwave Studio, using Wisconsin Diagnosis Breast Cancer Dataset. Features like the radius, texture, perimeter, area, and smoothness of the tumor are included along with their label data to determine whether the external shape has malignant or benign physiognomies. An explanation of the feasibility of the system deployment and technical recommendations to avoid interference is also described.

Structural health monitoring of a newly built high-piled wharf in a harbor with fiber Bragg grating sensor technology: design and deployment

  • Liu, Hong-biao;Zhang, Qiang;Zhang, Bao-hua
    • Smart Structures and Systems
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    • v.20 no.2
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    • pp.163-173
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    • 2017
  • Structural health monitoring (SHM) of civil infrastructure using fiber Bragg grating sensor networks (FBGSNs) has received significant public attention in recent years. However, there is currently little research on the health-monitoring technology of high-piled wharfs in coastal ports using the fiber Bragg grating (FBG) sensor technique. The benefits of FBG sensors are their small size, light weight, lack of conductivity, resistance corrosion, multiplexing ability and immunity to electromagnetic interference. Based on the properties of high-piled wharfs in coastal ports and servicing seawater environment and the benefits of FBG sensors, the SHM system for a high-piled wharf in the Tianjin Port of China is devised and deployed partly using the FBG sensor technique. In addition, the health-monitoring parameters are proposed. The system can monitor the structural mechanical properties and durability, which provides a state-of-the-art mean to monitor the health conditions of the wharf and display the monitored data with the BIM technique. In total, 289 FBG stain sensors, 87 FBG temperature sensors, 20 FBG obliquity sensors, 16 FBG pressure sensors, 8 FBG acceleration sensors and 4 anode ladders are installed in the components of the back platform and front platform. After the installation of some components in the wharf construction site, the good signal that each sensor measures demonstrates the suitability of the sensor setup methods, and it is proper for the full-scale, continuous, autonomous SHM deployment for the high-piled wharf in the costal port. The South 27# Wharf SHM system constitutes the largest deployment of FBG sensors for wharf structures in costal ports to date. This deployment demonstrates the strong potential of FBGSNs to monitor the health of large-scale coastal wharf structures. This study can provide a reference to the long-term health-monitoring system deployment for high-piled wharf structures in coastal ports.

Electrical Properties of PVdF/PVP Composite Filled with Carbon Nanotubes Prepared by Floating Catalyst Method

  • Kim, Woon-Soo;Song, Hee-Suk;Lee, Bang-One;Kwon, Kyung-Hee;Lim, Yun-Soo;Kim, Myung-Soo
    • Macromolecular Research
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    • v.10 no.5
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    • pp.253-258
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    • 2002
  • The multi-wall carbon nanotubes (MWNTs) with graphite crystal structure were synthesized by the catalytic decomposition of a ferrocene-xylene mixture in a quartz tube reactor to use as the conductive filler in the binary polymer matrix composed of poly(vinylidene fluoride) (PVdF) and poly(vinyl pyrrolidone) (PVP) for the EMI (electromagnetic interference) shielding applications. The yield of MWNTS was significantly dependent on the reaction temperature and the mole ratio of ferrocene to xylene, approaching to the maximum at 800 $^{\circ}C$ and 0.065 mole ratio. The electrical conductivity of the MWNTs-filled PVdF/PVP composite proportionally depended on the mass ratio of MWNTs to the binary polymer matrix, enhancing significantly from 0.56 to 26.7 S/cm with the raise of the mass ratio of MWNTs from 0.1 to 0.4. Based on the higher electrical conductivity and better EMI shielding effectiveness than the carbon nanofibers (CNFs)-filled coating materials, the MWNTs-filled binary polymer matrix showed a prospective possibility to apply to the EMI shielding materials. Moreover, the good adhesive strength confirmed that the binary polymer matrix could be used for improving the plastic properties of the EMI shielding materials.

Comparison of Magnetocardiogram Parameters Between a Ischemic Heart Disease Group and Control Group (정상군 및 허혈성 심질환 환자군에서의 심자도 파라미터 비교)

  • Park, Jong-Duk;Huh, Young;Jin, Seung-oh;Jeon, Sung-chae
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.11
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    • pp.680-688
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    • 2005
  • The electrical current generated by heart creates not only electric potential but also a magnetic field. We have observed electrophysiological phenomena of the heart by measuring components of magnetocardiogram(MCG) using 61 channel superconducting quantum interference device(SQUD) system. We have analyzed the possibility and characteristics of MCG parameters for diagnosis of ischemic heart disease. A technique for automatic analysis of MCG signals in time domain was developed. The methods for detecting the position, the interval, the amplitude ratio, and the direction of single current dipole were examined in the MCG wave. The position and interval parameters were obtained by calculating the gradients of a envelope curve which could be formed by the difference between the maximum and minimum envelope of multi-channel MCG signals. We show some differences of the frequency contour map between the normal MCG and the abnormal (ischemic heart disease) MCG. The direction of single current dipole can be defined by rotating the magnetic field according to Biot-Savart's law at each point of MCG signals. In this study, we have examined the direction of single current dipole from searching for the centroids of positive and negative magnetic fields. The amplitude ratio parameters for measuring 57 deviation consisted of A$_{T}$/A$_{R}$ and other ratios. and We developed a new analysis method, which is based on the frequency contour map of electromagnetic field. Using theses parameters, we founded significant differences between normal subjects and ischemic patients in some parameters.

A study on the parallel processing of the avionic system computer using multi RISC processors (다중 RISC 프로세서를 이용한 항공전자시스템컴퓨터 병렬처리기법 연구)

  • Lee, Jae-Uk;Lee, Sung-Soo;Kim, Young-Taek;Yang, Seung-Yul;Kim, Bong-Gyu;Hwang, Sang-Hyun;Park, Deok-Bae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.7
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    • pp.144-149
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    • 2002
  • This paper presents a technique for real time multiprocessor parallel processing to develop an avionic system computer(ASC) which integrates the avionics control, navigation and fire control, cursive and raster graphic symbol generation into one line replaceable unit. The proposed method has optimal performance by adopting a logically asymmetric structure between four 32bit RISC processors based on the master-slave multiprocessing, a tightly coupled interaction level with the time shared common bus and global memory, and an efficient bus arbitration algorithm. The ASC has been verified through a series of flight tests. The relevant tests also have been rigorously conducted on the prototype ASC such as electrical test, environmental test, and electromagnetic interference test.