• Current Optics and Photonics
• /
• 제3권1호
• /
• pp.16-21
• /
• 2019

We present a broad-bandwidth comb-spacing-swept source (CSWS) based on a differential polarization delay line (DPDL) for interferometric three-dimensional (3D) imaging. The comb spacing of the CSWS is repeatedly swept by the tunable DPDL in the multiwavelength source to provide depth-scanning optical coherence tomography (OCT). As the polarization differential delay of the DPDL is tuned from 5 to 15 ps, the comb spacing along the wavelength continuously varies from 1.6 to 0.53 nm, respectively. The wavelength range of various semiconductor optical amplifiers and the cavity feedback ratio of the tunable fiber coupler are experimentally selected to obtain optimal conditions for a broader 3-dB bandwidth of the multiwavelength spectrum and thus provide a higher axial resolution of $35{\mu}m$ in interferometric OCT imaging. The proposed CSWS-OCT has a simple imaging interferometer configuration without reference-path scanning and a simple imaging process without the complex Fourier transform. 3D surface images of a via-hole structure on a printed circuit board and the top surface of a coin were acquired.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.621-624
• /
• 1998

This paper presents a new configuration of dielectric bandpass filter using the comb-line filter design theory. This filter is composed of a homogeneous dielectric monoblock $(\varepsilonr=35.5)$ with two metal post and a dielectric sheet $(\varepsilonr=9.8).$ In this structure, the RF leakage is suppressed without other shield housing. For the fabricated filter, insertion loss value in the passband region was 0.9dB(Max.) and return loss value was 19dB(Min). Also, this filter has a attenuation pole in the stopband.

• 한국통신학회논문지
• /
• 제7권4호
• /
• pp.156-160
• /
• 1982

A Comb Filter(C.F.) is constucted with a N-stages one-dimensional B.B.D.(Bucket-Brigade Device) delay line. One channel of the B.P.F. (Band Pass Filter) Bank is experimented, which includes a R.F.(Recursie Filter) using S/H circuits cascaded to the C.F. This algorithm of the C.F.B.(Comb Filter Bank) becomes the parallel spectrum analyzer circuit. The algorithm has less number of multiplication than that of FFT and improves the SNR.

• 대한음성학회:학술대회논문집
• /
• 대한음성학회 2003년도 5월 학술대회지
• /
• pp.207-210
• /
• 2003

In this paper, the combinations of speech enhancement techniques are experimented. Specifically, the spectral subtraction, KLT based comb-filtering, and their combinations are applied to the Aurora2 database. The results show that recognition accuracy is improved when KLT based comb-filtering is applied after spectral subtraction.

• 대한음성학회지:말소리
• /
• 제46호
• /
• pp.65-76
• /
• 2003

In this paper, we employ the adaptive comb filtering for effective noise reduction in mobile communication environment. Adaptive comb filtering is a well-known method for noise reduction, but requires correct pitch period and must be applied just in voiced speech frames. To satisfy these requirements we use two kinds of information extracted from speech packets, one of which is the pitch period information measured precisely by a speech coder and the other is the frame rate information related to a decision on speech or silence frame. Experiments on speech recognition system confirm the efficiency of this method. Feature parameters employing this method give superior performance in noise environment to those extracted directly from output speech.

• 한국전기전자재료학회논문지
• /
• 제24권11호
• /
• pp.920-924
• /
• 2011

ZnO crystals with belt and comb shapes were synthesized without any catalysts through a simple thermal oxidation of ZnS powder in alumina crucible under air atmosphere. X-ray diffraction (XRD) pattern revealed that the ZnO crystals had wurtzite structure of hexagonal phase. Energy dispersive x-ray (EDX) spectra showed that the ZnO was of high purity. In the cathodoluminescece spectra obtained for the ZnO crystals with belt and comb shapes, a strong ultraviolet emission centered at 380nm was observed, which indicates the ZnO crystal has high crystalline quality.

• 한국전자파학회:학술대회논문집
• /
• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
• /
• pp.82-85
• /
• 2002

본 논문에서는 접지면에 어퍼쳐를 갖는 협대역 hairpin-comb 대역 통과 여파기를 제안하였다. Hairpin-comb 공진기는 두 공진기 사이의 간격이 매우 좁더라도 약한 커플링을 유지하는 특성이 있으므로 협대역 대역통과 여파기 제작시 여파기의 전체적인 크기를 작게 할 수 있는 장점이 있다. 그러나 일반적인 마이크로스트림에서는 공진기 사이가 최소한의 거리가 되더라도 커플링이 너무 미약하여 사용할 수 없다, 그러므로 접지면의 어퍼쳐를 사용하여 약한 커플링을 보상함으로써 일반 마이크로 스트립에서도 협대역을 대역통과 여파기를 제작할 수 있었다. 또한 공진기 사이의 거리변환 없이 어퍼쳐의 크기에 의해서 커플링을 조절함으로써 전체 여파기의 크기를 고정시킨 상태에서 대역폭을 조절할 수 있는 장점이 있다. 본 논문에서는 중심 주파수가 1.78 ㎓ 이고 대역폭이 62MHz(3.5%)인 여파기를 제작하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1974-1976
• /
• 1996

An electrostatically driven comb actuator with $525{\mu}m$ height was fabricated using (110) Si anisotropic etching in the Potassium Hydroxide(KOH) solution. The etch-rate and etch-rate ratio are strongly dependent on the weight % and temperature of KOH solution. We developed the optimal condition for the anisotropic etching on (110) wafer with varying these conditions. The force that the comb-drive actuator generates is inversely proportional to the distance of gap and proportional to the height of the comb electrodes. The electrodes must have the high aspect ratio. The (110) Si anisotropic etching is very useful to get a high aspect ratio structure.

• 한국재료학회지
• /
• 제9권2호
• /
• pp.195-198
• /
• 1999

The newly designed Ac-PDP(plasma display panel with comb-type electrode) structure was fabricated by using the screen printing method and the electrical and optical characteristics were measured under the various discharge conditions. The minimum firing voltages measured under pure Ne and Ne+Xe mixture gas with the application of 10 kHz square wave were 190V and 160V, respectively. The firing voltages of the PDP cell with the comb-type electrode were compared with those of the cell with matrix electrode under the same discharge condition. The firing voltage of the PDP cell with comb-type electrode was 15 V lower than that of the PDP cell with conventional matrix electrodes.

• 말소리와 음성과학
• /
• 제2권1호
• /
• pp.77-85
• /
• 2010

This paper proposes an efficient feature vector processing technique to guard the Speech Emotion Recognition (SER) system against a variety of noises. In the proposed approach, emotional feature vectors are extracted from speech processed by comb filtering. Then, these extracts are used in a robust model construction based on feature vector classification. We modify conventional comb filtering by using speech presence probability to minimize drawbacks due to incorrect pitch estimation under background noise conditions. The modified comb filtering can correctly enhance the harmonics, which is an important factor used in SER. Feature vector classification technique categorizes feature vectors into either discriminative vectors or non-discriminative vectors based on a log-likelihood criterion. This method can successfully select the discriminative vectors while preserving correct emotional characteristics. Thus, robust emotion models can be constructed by only using such discriminative vectors. On SER experiment using an emotional speech corpus contaminated by various noises, our approach exhibited superior performance to the baseline system.