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Time Frequency Domain Reflectometry 기법을 이용한 Coaxial Cable에서의 결함 감지 및 추정
송은석,신용준,최덕선,육종관,박진배,Powers, Edward J. 한국항행학회 2003 韓國航行學會論文誌 Vol.7 No.1
본 논문에서는 도선사에서 발생하는 결함 위치와 이상 유무를 감지하는 새로운 고분해능 반사측정법인 시간-주파수 영역반사측정법 (TFDR, Time-Frequency Domain Reflectometry)을 제안하였다. 고전적인 반사측정법들은 단지 시간 또는 주파수의 한 영역에서 분석되어져 왔으나, 본 논문에서 제시한 TFDR은 도선의 결함 위치와 이상 유무를 발견하기 위해 과도신호의 시간과 주파수 영역의 정보를 동시에 이용할 수 있는 시간-주파수 분석기법으로 특성화하였다. TFDR의 기준신호 설계는 측정 케이블의 물리적 성질들을 고려하여 주파수 밴드를 결정하며, 도선의 결함감지와 추정은 시간-주파수 상호상관관계 함수에 의해 이루어진다. TFDR 시스템을 이용하여 여러 결함 상태를 가진 실제 coaxial cable (RG-142, RG-400)에 대해 실험하였고 정확성을 입증하기 위해 TDR (Time Domain Reflectometry) 장비와 성능은 비교하였다. 본 논문에서는 TFDR이 TDR보다 작은 오차로 결함을 찾아냄을 나타내고 있으며, 측정된 정확도는 TFDR의 오차율이 0.5%이하로 TDR (54750A/54754A) 장비보다 성능이 월등히 우수하다는 것을 알 수 있다. In this paper, a new high resolution reflectometry scheme, time-frequency domain reflectometry (TFDR), is proposed to detect and locate fault in wiring. Traditional reflectometry methods have been achieved in either the time domain or frequency domain only. However, time-frequency domain reflectometry utilizes time and frequency information of a transient signal to detect and locate the fault. The time-frequency domain reflectometry approach described in this paper is characterized by time-frequency reference signal design and post-processing of the reference and reflected signals to detect and locate the fault. Design of the reference signal in time-frequency domain reflectometry is based on the determination of the frequency bandwidth of the physical properties of cable under test. The detection and estimation of the fault on the time-frequency domain reflectometry relies on the time-frequency domain reflectometry is compared with commercial time domain reflectometry (TDR) instrument. In these experiments provided in this paper, TFDR locates the fault with smaller error than TDR. Knowledge of time and frequency localized information for the reference and reflected signal gained via time-frequency analysis, allows one to detect the fault and estimate the location accurately.
Modified Slot-Loaded Multi-Band Microstrip Patch Antenna
Jong-Gwan Yook,Han-Kyu Park,Man-Shik Cho,Il-Kwon Kim,Han-Back Cho 한국전자파학회JEES 2003 Journal of Electromagnetic Engineering and Science Vol.3 No.1
In this paper, a triple-band planar antenna is proposed for the application to miniaturized automobile safety devices operating at X band(10.5 GHz), K band(24.15 GHz), and Ka band(34.3 GHz). The frequency ratio between the resonant frequencies of this antenna can be adjusted from 1.99 to 2.23 for both X band and K band by varying its slit length. Parasitic elements are added on the modified slot loaded antenna to obtain the third resonance. From numerical as well as experimental results, it has been confirmed that this type of antenna is appropriate for planar multi-band antenna systems.
Analysis of EMI Problems in Plit Power Distribution Network
Jong-Gwan Yook,Han-Kyu Park,Hwang-Yoon Shim,Ji-Seong Kim 한국전자파학회JEES 2002 Journal of Electromagnetic Engineering and Science Vol.2 No.2
Signal integrity problems and their possible solutions are addressed in this paper for split power plane of high-speed digital systems. Stitching and decoupling capacitors are proved to be very effective for reducing signal noise, ground bounce as well as electromagnetic radiation from the split power plane. Simulations based on 3D-Finite Difference Time Domain(FDTD) method are utilized for the analysis of practical high frequency multi-layered PC main board.
Jong Hwa Kwon,Dong Uk Sim,Sang Il Kwak,Jong Gwan Yook IEEE 2010 IEEE transactions on electromagnetic compatibility Vol.52 No.2
<P>To supply high-speed digital circuits with stable power, power/ground noise, such as simultaneous switching noise (SSN) and ground bounce noise caused in multilayer printed circuit boards (PCBs) and packages need to be sufficiently suppressed. The electromagnetic bandgap (EBG) is widely recognized as a good solution for suppressing the propagation of SSN in the gigahertz range. However, a typical coplanar EBG structure etched onto the power and ground planes may degrade the quality of high-speed signals passing over the perforated reference plane. In this paper, a novel method of arranging EBG unit cells on both the power/ground planes in multilayer PCBs and packages is proposed, not only as a means of sufficiently suppressing the propagation of power noise, but also as a means of minimizing the effect of EBG-patterned reference planes on a high-speed signal. On the assumption that noise sources and noise-sensitive devices exist only in specific areas, the proposed method partially positions EBG unit cells only near these critical areas. The SSN suppression performance of the proposed structure is verified by conducting simulations and measurements in the time and frequency domains. Furthermore, signal quality is investigated to verify whether the proposed EBG-patterned reference planes are superior to conventional EBG-patterned planes in terms of signal integrity.</P>
Kwon, Jong-Hwa,Sim, Dong-Uk,Kwak, Sang-Il,Gwan Yook, Jong Wiley Subscription Services, Inc., A Wiley Company 2009 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.51 No.5
<P>To build a stable power distribution network for high-speed digital systems, simultaneous switching noise (SSN) in multilayer PCBs and packages needs to be sufficiently suppressed. In this article, a novel triangular-type uniplanar compact electromagnetic band-gap with different bridges designed for power/ground planes is proposed for the ultra-broadband suppression of SSN. The SSN suppression performance of the proposed structure is validated both numerically and experimentally. A −30 dB suppression bandwidth for SSN is achieved starting at 800 MHz and extending to 15 GHz and beyond, that is, almost the entire noise band. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1356–1358, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24322</P>
KWON, Jong Hwa,SIM, Dong Uk,KWAK, Sang Il,YOOK, Jong Gwan The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.6
<P>To build a stable power distribution network for high-speed digital systems, simultaneous switching noise (SSN) should be sufficiently suppressed in multi-layer PCBs and packages. In this paper, a novel hybrid uni-planar compact electromagnetic bandgap (UC-EBG) with two triangular-type unit cells designed on power/ground planes is proposed for the ultra-broadband suppression of SSN. The SSN suppression performance of the proposed structure is validated both numerically and experimentally. A -35dB suppression bandwidth for SSN is achieved, starting at 800MHz and extending to 15GHz and beyond, thereby covering almost the entire noise band.</P>
KWON, Jong Hwa,YOOK, Jong Gwan The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.7
<P>In this paper, a novel method of partially placing electromagnetic band-gap (EBG) unit cells on both the power and ground planes in multi-layer PCBs and packages is proposed; it can not only sufficiently eliminate simultaneous switching noise (SSN), but also prevent severe degradation of signal quality in high-speed systems with imperfect reference planes resulting from the perforated structures of uni-planar EBG unit cells. On the assumption that the noise sources and noise-sensitive devices exist only in specific areas, the proposed method partially arranges the EBG unit cells on both the power and ground planes, but only around the critical areas. The SSN suppression performance of the proposed structure is verified by a simulation and measurements.</P>