• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.291-297
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• 1996

To visualize sound field or to identify noise sources, we can use many methods such as intensity method, acoustic holographic method, source identification method using line array, etc. Conventionally all these methods are performed with the assumption of stationary condition in space and time. But for moving source, spatial characteristics and frequency components are changing, so we need another processing algorithm. This paper shows some experimental results - sound field by moving noise sources. In the experiment cross type microphone line array is used for sensing pressure and cars and a motorcycle are used as moving sources that are assumed to have constant speed. The processing methods are acoustic holographic method, spherical beamforming and spectrogram.

• 한국음향학회지
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• 제43권1호
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• pp.89-94
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• 2024

Ultra-Short BaseLine(USBL) 은 센서 간격이 좁은 배열을 사용하기 때문에 위치 추정 성능 향상을 위해서는 정밀한 동기화가 필요하다. 그러나 수중 환경은 비교적 강한 잡음과 다중 경로 및 도플러 등의 수중 음향 채널로 인해 동기화 오류가 발생하여 위치 추정 성능이 저하된다. 본 논문에서는 수중 USBL 시스템의 위치 추정 성능을 향상시키기 위한 공분산 기반 동기 보상 기법을 제안한다. 제안 방법은 상호상관을 통해 신호를 정렬한 후, 정렬된 신호의 공분산을 계산한다. 공분산에서 동기 오차는 위상차와 선형적으로 관련되어 있으므로 위상차를 공분산으로부터 추정하여 동기 오차를 보상한다. 전산 모의실험을 통해 제안 방법이 기존 상호상관 방법보다 우수한 위치 추정 성능을 가지는 것을 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.428-430
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• 2007

Converter that is dc source equipment source's phase by reference control function that detect source's phase because should be done compulsorily use. Source's phase detect method there be method that use source's ac voltage directly by signal, and use methods that voltage detects status by PLL method and so on via point that '0' becomes usually. All above methods to detect phase are using, wrong action of phase detector converter's ailment or converter of burn can. Ths paper compares and examined usable phase detection method in source's frequency fluctuation presuming source's frequency using observer.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.155-158
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• 2000

A new control method for single-phase shunt active power line conditioners(APLC's) operated under zero average power consumption is proposed in this paper. The amplitude of the sinusoidal source current which is in-phase with the source voltage can be determined from the average value of the instantaneous load power. Then the command current for the shunt APLC is obtained by subtraction the source current from the load current. Neither bulky filter nor time-consuming computation is required. The shunt power compensator supplies all the harmonics of he load current and the source only supplies the fundamental component,. Experimental results on a prototype verify the feasibility of the presented scheme,

• 대한전자공학회논문지TC
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• 제44권6호
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• pp.57-63
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• 2007

본 논문에서는 모노 펄스 추적용 배열안테나에서 주로 사용하는 선전원에 의한 차패턴 합성법을 새로이 제안한다. 제안한 방법에서는 잘 알려진 Bayliss의 차패턴 합성법과는 달리 Taylor의 선전원 합패턴 공식을 적절히 수정하여, 원하는 개별 sidelobe 레벨을 갖는 차패턴을 최적 합성한다. 즉, 차패턴과 해당 소스 분포함수와의 관계를 해석적으로 설정하고, 패턴이 갖는 null점을 최적으로 섭동시킴으로써 원하는 패턴과 해당 소스 분포함수를 동시에 도출한다. 더욱이 이 방법은 기존의 방법보다 빠른 sidelobe 감쇠율을 가지도록 한다. 수치적인 결과들로부터 제안한 합성과정의 타당성과 유용성을 보인다.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1251-1264
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• 2018

The systematic and effective design method of a Class-D current-source resonant inverter for use in an induction cooker with zero-ripple line current is presented. The design procedure is based on the principle of the Class-D current-source resonant inverter with a simplified load network model that is a parallel equivalent circuit. An induction load characterization is obtained from a large-signal excitation test-bench based on parallel load network, which is the key to an accurate design for the induction cooker system. Accordingly, the proposed scheme provides a systematic, precise, and feasible solution than the existing design method based on series-parallel load network under low-signal excitation. Moreover, a zero-ripple condition of utility-line input current is naturally preserved without any extra circuit or control. Meanwhile, a differential-mode input electromagnetic interference (EMI) filter can be eliminated, high power quality in utility-line can be obtained, and a standard-recovery diode of bridge-rectifier can be employed. The step-by-step design procedure explained with design example. The devices stress and power loss analysis of induction cooker with a parallel load network under large-signal excitation are described. A 2,500-W laboratory prototype was developed for $220-V_{rms}/50-Hz$ utility-line to verify the theoretical analysis. An efficiency of the prototype is 96% at full load.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2004년도 학술발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.73-84
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• 2004

• 대한수학회보
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• 제52권5호
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• pp.1495-1515
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• 2015

This paper deals with the numerical methods for the reconstruction of the source term in a linear parabolic equation from final overdetermination. We assume that the source term has the form f(x)h(t) and h(t) is given, which guarantees the uniqueness of the inverse problem of determining the source term f(x) from final overdetermination. We present the regularization methods for reconstruction of the source term in the whole real line and with Neumann boundary conditions. Moreover, we show the connection of the solutions between the problem with Neumann boundary conditions and the problem with no boundary conditions (on the whole real line) by using the extension method. Numerical experiments are done for the inverse problem with the boundary conditions.

• Journal of Power Electronics
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• 제16권3호
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• pp.1087-1096
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• 2016

This paper reports an investigation conducted on two diagnostic methods based on the switching voltage pattern of IGBT open-circuit faults in voltage-source inverters (VSIs). One method was based on the bridge arm pole voltage, and the other was based on bridge arm line voltage. With an additional simple circuit, these two diagnostic methods detected and effectively identified single and multiple open-circuit faults of inverter IGBTs. A comparison of the times for the diagnosis and anti-interference features between these two methods is presented. The diagnostic time of both methods was less than 280ns in the best case. The diagnostic time for the method based on the bridge arm pole voltage was less than that of the method based on the bridge arm line voltage and was 1/2 of the fundamental period in the worst case. An experimental study was carried out to show the effectiveness of and the differences between these two methods.

• 전기학회논문지
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• 제58권5호
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• pp.885-890
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• 2009

A fault location algorithm using estimated local source impedance after a fault is proposed in this paper. The method uses after fault data only at the local end. It uses the negative sequence current distribution factor for more accurate estimation. The proposed algorithm can keep up with the variation of the local source impedance. Therefore, the proposed algorithm especially is valid for a transmission line interconnected to a wind farm that the equivalent source impedance changes continuously. The performance of the proposed algorithm was verified under various fault conditions using the Simpowersystem of MATLAB Simulink. The proposed algorithm is largely insensitive to the variation in fault distance and fault resistance. The test results show a very high accurate performance.