• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.214-215
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• 2010

본 논문은 공진 인버터를 적용한 HID램프를 구동하기 위한 전자식 안정기를 설계하고 구현하였다. 제안된 전자식 안정기는 스위치 턴온 오프시의 손실을 줄이기 위해서 소프트 스위칭 기법인 ZVS(Zero-Voltage Switching)을 도입하였다. 점등은 LC필터의 공진주파수범위에서 풀브리지 인버터 제어에 의한 공진으로 이루어 진다. 점등후에 컨버터는 저주파수 구형파로 동작한다. 공진 기동시의 LC필터의 공진주파수는 ($f_o$=160kHz)이고, 고조파를 감소시키고 음향공진현상을 피하기 위한 벅컨버터 스위칭 주파수(고주파수 : 50~60kHz 와 저주파수 : 170Hz)를 선택하였다. 실험을 통해 공진 인버터를 적용한 HID램프용 전자식 안정기가 안정적으로 동작함을 확인하였다.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.182-184
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• 2009

본 논문은 램프 점등을 위한 공진회로와 정상상태에서의 저주파수 구형파(low frequency square-wave) 인버터 전류 제어를 실현하는 HID 전자식 안정기에 풀브리지 인버터(FB)와 LC 필터를 제안한다. 점등은 LC필터의 공진주파수에서 풀브리지 인버터 제어에 의한 공진에 의해서 이루어지고, 점등 후에 회로는 풀브리지 제어에 의해 벅컨버터 저주파수 구형파 인버터로 동작한다. 점등이 일어나는 동안의 LC필터의 공진주파수는 ($f_o$=120kHz)이고, 고조파를 감소시키고 음향공명현상을 피하기 위한 벅컨버터스위칭 주파수($f_{sw}$=50kHz)를 선택하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.10a
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• pp.849-853
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• 1998

라인 해석법(Method of Line), MOL과 파수 영역 해석법(Space Domain Approach), SDA를 결합한 공간-파수 영역 해석법(SSDA)를 이용하여 MIC/MMIC 회로에서 임의 입체 구조를 갖는 공진기를 해석한다. SSDA는 상대 수렴(relative convergence)특성을 갖지 않으며, 반 해석적 (semianalytical )특성으로 수치적 효율이 높다. 경계치 문제로부터 씨스팀 행렬방정식 형태로 유도된그린 함수에 갤러킨법을 적용한다. 삼각, 사각 및 불연속 구조를 갖는 스트립 패치의 폭, 위치와 기판의 두께 변화에 따른 공진 주파수를 계산하였다.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.91-99
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• 2001

Spectral domain of resonant frequency rectangular microstrip patch antenna on anisotropic substrates and superstrate with airgap are analyzed. First, we derive dyadic Green function for selected anisotropic material by constitutive relation and then formulate integral equations of electric fields using Fourier transform in space region. Using Galerkin's moment method, we discretize the electric field integral equations Into the matrix form and select sinusoidal functions as basis functions. We verify the validity of numerical results and compare the results with existing ones in showing a good agreement between them. The resonant frequencies in the variation of air gap, patch length and permittivity of superstrate anisotrpy ratio of anisotrpic superstrate are presented and analyzed.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.150-159
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• 2002

The possibility of a broadband noise reduction of piezoelectric smart panels is experimentally studied. Piezoelectric smart panel is basically a plate structure on which piezoelectric patch with shunt circuits is mounted and sound absorbing material is bonded on the surface of the structure. Sound absorbing materials can absorb the sound transmitted at mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to tune the piezoelectric shunt circuit, the measured electrical impedance model is adopted. Resonant shunt circuit composed of register and inductor in stories is considered and the circuit parameters are determined based on maximizing the dissipated energy through the circuit. The transmitted noise reduction performance of smart panels is investigated using an acoustic tunnel. The tunnel is a square crosses sectional tunnel and a loud speaker is mounted at one side of the tunnel as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across the panels is measured. Noise reduction performance of a double smart panel possessing absorbing material and air gap shows a good result at mid frequency region except the first resonance frequency. By enabling the piezoelectric shunt damping, noise reduction is achieved at the resonance frequency as well. Piezoelectric smart panels incorporating passive method and piezoelectric shunt damping are a promising technology for noise reduction in a broadband frequency.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.45-54
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• 2015

This paper presents the influence of backlash can be greatly increased on the frequency response characteristic which is presented as the angular velocity of a motor to the motor input voltage, if the motor input voltage is adequately reduced. And, this paper verifies theoretically, analytically and experimentally the availability on the method of detecting the change of backlash magnitude by investigating on the change of the anti-resonance and resonance frequencies in the frequency response characteristic due to the change of backlash magnitude. The amount of change of anti-resonance frequency is more useful that of resonance frequency when detecting the change of backlash magnitude, because the change of anti-resonance frequency can be measured more stable. This paper also shows the sharp change of resonance frequency can be investigated when the motor input voltage is enough reduced. The work will be useful for the further research on the backlash estimation method of a servo system with a gear reducer.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.226-227
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• 2000

Laser Doppler velocimeters: (LDV)$^{1)}$ 의 대부분의 기본원리는 호모다인(honodyne)방법을 사용한다. 호모다인 방법 중에서 많이 사용되는 방법으로는 마이켈슨 간섭계식과 되먹임식(self-mixing type)$^{2)}$ 이 있다. 마이켈슨 간섭계식은 구성하는데는 많은 광학부품과 정밀한 정렬 장치들을 필요로 한다. 반면에 되먹임식은 레이저 공진기의 고유 주파수와 도플러 이동된 산란광을 공진기 속에서 자체 혼합하여 발생한 차주파수를 레이저 공진기 내부에 있는 pin-photodiode로 측정하므로 마이켈슨 간섭계에 비하여 간단한 장치로 속도계를 구성할 수 있다. (중략)

• The Journal of the Acoustical Society of Korea
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• v.31 no.8
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• pp.507-513
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• 2012

The room modes were showed as the peaks and dips on the low frequency response of the loudspeaker, and were one of the biggest obstacles to reproduce the sound. In order to reduce the occurrence of resonance, equalizing is performed at one position, and the frequency response to be equalized is valid only at that position. Performing the equalization would improve the flatness of the frequency response a little, but it cannot eliminate the ringing. Another method is that it is located the speaker at the specific position where the room resonances were not frequently happened. However, there may be the practical limitation that you may not be able to install the speaker at the position to be wanted. One of the practical solutions to decrease the production of resonance in room is the use of bass trap. In this paper, the practical limit for the room tuning using an equalizer and the room optimization will be discussed. The use of bass traps to solve the resonance problem that is always happened in the room is also proposed.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.479-480
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• 2011

본 논문은 150W HID 램프용 안정기의 공진 점등에 관한 것으로, 기존의 외부 펄스에 의한 점등 시 램프와 안정기의 거리에 따른 점등전압의 감쇠를 감소시키고자 내부 LC를 이용한 공진 점화부로 하여 기능을 향상하였으나, 벅 컨버터의 인덕터와 커패시터로 공진 기동하여 고전압 점등 파형을 만드는 과정 중 스위치 전류가 커지는 문제가 발생하여, 점등을 위한 공진용 커패시터용량을 줄여 공진 Q점을 나눈 별도의 L(T1)과 C(C2, C3)를 공진 탱크로 이용하여 점등하도록 하였으며, 공진 공진주파수로의 주파수 SWEEP 및 재 점등을 하기 위하여 마이크로프로세서를 이용하였다.

• Korean Journal of Optics and Photonics
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• v.22 no.2
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• pp.72-76
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• 2011

We demonstrate a k-domain linearization using a fiber Bragg grating (FBG) array for Fourier domain optical coherence tomography based on a wavelength swept laser. The k-domain linearization is carried out with an interpolation method using a FBG array with five FBGs. The measured signal-to-noise ratio from the point spread function after k-domain linearization is 12 dB improved over that of without k-domain linearization at the 1 mm depth of the sample. Clear OCT imaging of the slide glass with k-domain linearization could be obtained.