• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.786-791
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• 2005

This paper is concerned with the examination and evaluation concerning a tuning method of multivariable PID controllers based on partial model matching on frequency domain proposed by authors from practical view point. In this case, PID controller parameters are determined by minimizing the loss function defined by the difference between frequency response of ideal model transfer function and actual frequency response on several frequency points. The purpose of the paper is to examine and evaluate the performance of the method through actual experiments of MIMO liquid level experimental process control equipment.

• 반도체디스플레이기술학회지
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• 제6권2호
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• pp.29-33
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• 2007

Low frequency (400 kHz) Ferrite ICP has been proposed for large area processing. Because the coupling coefficient is close to 1, the transformer matching can be adapted to Ferrite ICP. The transformer matching system is simple. In this paper the new matching system by controlling the turns of transformer using relays is proposed for impedance matching. We developed a simple matching system and characterized it when the turns were changed. It was observed that the 2-channel relay is available for transformer matching.

• 말소리와 음성과학
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• 제4권4호
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• pp.139-146
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• 2012

This study was designed to examine comfort levels of pitch and loudness with target matching and their effects on electroglottographic (EGG) and acoustic measures. Twelve speakers, six males and six females, were instructed to produce /a/ sustained vowel for three seconds at a comfortable pitch and loudness level without any instruction and with a target matching procedure of either a certain f0 or SPL separately with visual and auditory feedback. The range of pitch for females and males were presented by progressing up and down randomly at intervals of 5Hz from 150 Hz to 310 Hz (total 33 frequency targets) and from 85 Hz to 190 Hz (total 22 frequency targets), respectively. The loudness levels were 65, 75, 85, 95 dB (total of four intensity targets) for both males and females. Subjective estimations of comfortable levels were obtained using a 10-point equal-appearing interval rating scale following each phonation. The results showed that males and females demonstrated similar trends in loudness levels with greatest comfort at 75 dB, whereas pitch comfort ratings showed a greater variability with females having a wider range with target matching. In the comfort levels of individuals, most male and female speakers rated higher comfort at soft, rather than loud phonations. On the other hand, most male speakers perceived highest comfort levels below the comfort pitch levels they phonated under natural conditions. Higher frequency ranges, however, were perceived to be more comfortable than those of natural condition in most female speakers, although the comfortable pitch levels in spontaneous phonations were within the comfort level ranges determined by targeted phonations. When comparing acoustic (%jitter, %shimmer, SNR) and EGG measures (CQ%) between spontaneous comfortable phonations and targeted phonations produced by the same subject at similar f0 and intensity, no significant differences were observed (p>0.05). Thus, target matching procedures may be considered a compatible and alternative method to reduce the variability of comfortable pitch and loudness levels by eliciting consistent comfortable phonations.

• 한국수산과학회지
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• 제52권6호
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• pp.702-708
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• 2019

The range resolution of echo sounders can be improved by enhancing the transducer bandwidth. We designed a bandpass matching network for expanding the bandwidth of a transducer by scaling in both impedance and frequency after transforming a lowpass network into a bandpass configuration for a third-order Bessel filter. We measured the effect of the Bessel matching network for a 50 kHz sandwich type transducer on the transmitting voltage response (TVR), receiving sensitivity (SRT) and figure of merit (FOM), using a chirp echo sounder system. Both the simulation and experimental results indicated that the transducer with a bandpass matching network was capable of producing a symmetrical acoustic output over a wider bandwidth (8.25 kHz) than was the transducer without a matching network (3.75 kHz). By implementing the Bessel matching network, we achieved a 120% bandwidth enhancement.

• Journal of Electrical Engineering and Technology
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• 제6권6호
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• pp.776-785
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• 2011

Since the Internet-based real-time Global Positioning System(GPS) synchronized widearea power system frequency monitoring network (FNET) was proposed in 2001, it has been monitoring the power system frequency in interconnected United States power systems and numerous interesting behaviors have been observed, including frequency excursion propagation. We address the consistency of a frequency excursion detection order of frequency disturbance recorders in FNET in relation to the same generation trip, as well as the ability to recreate by power systems dynamic simulation. We also propose a new method, as an application of FNET measurement, to locate a tripped generator using power systems dynamic simulation and wide-area frequency measurement. The simulation database of all the possible trips of generators in the interconnected power systems is created using the off-line power systems dynamic simulation. When FNET detects a sudden drop in the monitoring frequency, which is most likely due to a generation trip in power systems, the proposed algorithm locates a tripped generator by finding the best matching case of the measured frequency excursion in the simulation database in terms of the frequency drop detection order and the time of monitoring points.

• 한국자기학회지
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• 제3권2호
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• pp.115-120
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• 1993

화학양론적 조성을 갖는 Ni-Zn ferrite에서 Ni/Zn 비의 변화에 따른 전파흡수체의 성능 평가 지수, 정합주파수 및 정합두께와 자기적인 변수와의 상관관계를 조사하였다. Ni/Zn 비가 감소 할수록 ${\mu}_{r}$의 최대치는 저주파수 영역으로 이동하며 Ni/Zn 비가 1.0인 경우 ${\mu}_{r}$의 값은 다른 조성에 비해 높은 값을 가짐을 확인할 수 있었다. Ni/Zn ferrite 복합제는 1-12 GHz 영역에서 2개의 정합주파수($f_{m1}$, $f_{m2}$)및 정합두께 ($d_{m1}$, $d_{m2}$)가 존재하며 $f_{m1}$은 $f_{r}$(공명주파수)과 비례하며 $f_{m2}$는 포화자화값에 비례함을 확인하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권6호
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• pp.409-416
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• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권5호
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• pp.345-352
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• 2004

Currently, high data rate PLC(Power Line Communications), up to 100 Mbps, which use frequency bandwidth between 2 MHz and 30 MHz is investigated very hard, and commercial PLC modem for low voltage powerline network (indoor) is coming soon into communication market. For the purpose of developing a fit communication system which has little distortion of signal and attenuation, it is surely necessary to know about channel environments of powerline. Especially, the impedance measurement of the powerline and impedance matching are very important. As is known, since medium-voltage powerline (22.9 ㎸) is still working, it is not so simple to measure the powerline impedance. In our study, a portable impedance measurement equipment is developed. It consists of coupling capacitor, a drain coil and impedance matching transformer. The equipment is easily connected to medium voltage line and impedance of power line is measured using a network analyzer. Also, measurement results are used for impedance matching of PLC signal. In fact, matching transformer with several different impedances are used. The matching transformer is connected between coupling capacitor and signal port. In this paper, the developed portable impedance measurement equipment and impedance measurement results are presented. Also impedance matching technique using matching transformers will be explained. We showed the result of the improved performance by the impedance matching.

• 센서학회지
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• 제27권6호
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• pp.374-379
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• 2018

The piezocomposite transducer is widely used because it is highly efficient in transforming electric energy into mechanical energy, and its frequency range is broader than that of other types of ultrasound transducers. A general piezocomposite transducer is composed of an acoustic lens, impedance matching layers, piezoelectric materials, and backing layers. When an input voltage is applied to a piezoelectric material as an active material, it generates sound waves while vibrating. At that time, an impedance matching layer helps the sound waves to propagate forward while reducing the impedance mismatch that may occur at the interface between the active material and its front material. The impedance mismatch has a negative effect on the signal of an ultrasound transducer; thus, it is important to design a matching layer to overcome the issue. In this study, an optimized feature of a matching layer with gradient properties is studied. An objective function is defined to minimize both the average and the deviation of the reflection coefficients that are functions of the frequencies. As a result, an improvement in the signal characteristics with respect to the sensitivity and bandwidth is reported.

• 한국멀티미디어학회논문지
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• 제7권9호
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• pp.1255-1262
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• 2004

본 논문은 잡음이 포함된 화상의 패턴매칭 및 검증에 유효한 새로운 패턴매칭 알고리듬을 제안한다. 이 알고리듬은 화상을 푸리에변환하면 중요한 형상정보가 푸리에영역의 저주파영역에 집중된다는 데 착안하여, 푸리에영역에 나타난 화상의 원점부근만을 추출하여 비교하는 방법을 이용하고 있다. 구체적으로는 두화상의 푸리에변환한 화상의 원점부분을 추출하여 감산하고 경험적인 임계치를 적용함으로써 패턴인식이 가능함을 보인다. 본 방법은 특히 잡음이 포함된 화상과 원화상의 매칭에도 효과적이다. 잡음은 푸리에영역에서 일반적으로 고주파영역에 분포하는데 본 방법 은 저주파영역을 추출하여 비교하기 때문이다. 실험결과는 10개의 표준화상과 가우시안잡음이 첨가된 화상을 사용하여 화상을 구분해 내고, 잡음이 있는 화상도 동일한 화상으로 인식함을 보여 준다. 이 방법을 화상의 위상정보만을 이용하여 패턴인식을 수행하는 위상한정상관법과 비교한 결과, 일부의 경우에 위상한정상관법과 동등이상의 결과를 보여준다.