• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.435-441
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• 2017

Detecting an inter-harmonic accurately is not easy work, because it has small magnitude, and its frequency which can be observed is not an integer multiple of fundamental frequency. In this paper, a new method using filter bank system and adaptive predictor is proposed. Filter bank system decomposes input signal to sub bands. In adaptive predictor, inter-harmonic is detected with decomposed sub band signal as input, and error signal as output. In this scheme, input-output characteristic of adaptive predictor is notch filter, as predicted harmonic is canceled in error signal, so detecting an inter-harmonic can be possible. Magnitude and frequency of detected inter-harmonic is estimated by recursive algorithm. The performances of proposed method are evaluated to sinusoidal signal model synthesized with harmonics and inter-harmonics. And validity of the method is proved as comparing the inter-harmonic detection results to MUSIC and ESPRIT.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4_1
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• pp.137-150
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• 1992

A complete solution, exact to second-order, for wave motion forced by a hinged-wavemaker of variable-draft is presented. A solution for a piston type wavemaker is also obtained as a special case of a hinged-wavemaker. The laboratory waves generated by a plane wave board are shown to be composed of two components; viz., a Stokes second-order wave and a second-harnomic free wave which travels at a different speed. The amplitude of the second-harmonic free wave is relatively large in shallow water and decreases to less than 10% of the amplitude of the primary wave in deep water. Wavemakers with relatively deeper draft (i.e., hinged near the bottom) generate the free waves of smaller amplitude in shallow and intermediate water depths than the wavemakers with shallow draft. However, the opposite is predicted by theory in deep water.

• Journal of Korea Water Resources Association
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• v.45 no.6
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• pp.545-555
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• 2012

A numerical modeling has become increasingly popular and more important to the study of water waves with a rapid advancement of computer technology. However, different types of problems are induced during simulating wave motion. One of the key problems is re-reflection to a computation domain at the incident boundary. The internal wave generating-absorbing boundary conditions have been commonly used in numerical wave models to prevent re-reflection. For the Navier-Stokes equations model, the internal wave maker using a mass source function of the continuity equation has been used to generate various types of waves. Nonetheless, almost every numerical experiment is performed in two dimensions and only a few tests have been expanded to three dimensions. More recently, a momentum source function of the Boussinesq equations is applied to generate essentially directional waves in the three dimensional Navier-Stokes equations model. In this study, the internal wave maker using a momentum source function is employed to generate targeted linear waves in the three-dimensional LES model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.401-406
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• 2011

In this study, generation methods of oblique incident wave are newly proposed and examined using the fully non-linear numerical model with non-reflected wave generation system(LES-WASS-3D). In order to verify, free surface elevation and horizontal velocities are compared with $3^{rd}$ -order Stokes wave theory in 3-D oblique incident wave field. As a results, it is revealed that the numerical results by newly proposed technique are in good agreement with the theory.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.4
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• pp.169-179
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• 2017

In this study, we applied the wave generation method by relaxation method to the SWASH model, which is a non - hydrostatic numerical model, for stable and accurate wave generation of linear and nonlinear waves. To validate the relaxation wave generation method, we were simulated various wave, including the linear wave and nonliner wave and compared with analytical solution. As a result, the incident wave was successfully generated and propagated in all cases from Stokes waves to cnoidal wave. Also, we were confirmed that the wave height and the waveform were in good agreement with the analytical solution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.653-662
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• 1999

In this paper, subharmonically injection locked oscillator(SILO) was designed and measured. SILO with series feedback was designed using Two Signal Method(TSM). The free-running oscillator frequency was 9.4 GHz with 6 dBm output power. In case of injection, the multiplied injected signal locked the free-running frequency. The locked signal output power was higher than any other spurious response at least 40 dB. The locking range was 220MHz (second subharmonic locking), 100 MHz(4th subharmonic locking), and phase noise was -111 dBc/Hz, -104 dBc/Hz at 100kHz offset, respectively.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.23-24
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• 2017

본 논문은 무정전전원장치의 전압품질 향상을 위한 디지털 홀수고조파 반복제어기 설계기법에 대해 기술한다. 반복제어기의 설계를 위해 전체 제어시스템을 설계하고, 반복제어기가 안정하기 위한 기준을 제시한다. 비선형 부하에 대해 반복제어기를 적용함으로써, 인버터 출력전압의 홀수고조파 성분을 효과적으로 보상할 수 있으며, 이를 모의실험 및 실험으로 확인한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.59-63
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• 2008

This paper analyze the operating characteristic of RCB due to the synthesize harmonic current. The RCB of rated sensitivity electric current with 30[mA] test to operating characteristic by synthesize harmonic current and it analyzed the tripping operation due to a harmonic current. The test result, the operating current of RCB changed by synthesize harmonic current.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.53-58
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• 2008

This paper analyze the operating characteristic of MCCB due to the synthesize harmonic current. Four types of MCCBs, divided by the type of operation system and a principle of operation, tested with 200[%] of rated current. The test result nuisance tripping did not occur but the time delay characteristic of the hydraulic magnetic type MCCB is appeared. From the place where the synthesize harmonic content is high it is good the hydraulic magnetic type MCCB not to use.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2009.10a
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• pp.224-227
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• 2009