• The Journal of the Acoustical Society of Korea
• /
• v.25 no.1
• /
• pp.30-35
• /
• 2006

In this paper. we Propose a frequency domain beamforming algorithm composed of inverse-filtering stages followed by a MVDR (Minimum-Variance Distortionless Response) beamformer or a GSC (Generalized Sidelobe Canceller). The proposed method is shown to require less complexity than the conventional RTF-MVDR and TF-GSC. respectively, and it is shown that the Proposed method is equivalent to the conventional RTF-MVDR and TF-GSC in optimum solution. In order to evaluate the performance of the Proposed method. speech recognition experiments are performed using the speech database recorded in a car. The Proposed method shows equal or slightly degraded Performance comparing to the conventional methods in terms of the speech recognition rate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.6
• /
• pp.533-539
• /
• 2004

In this work, in order to realize a band pass filter with wide-band characteristics for mobile communications, 2 GHz band pass filter was designed using ring resonator with stub. The three stage wide-band BPF was designed and fabricated. For broadband design, the ring circumference was divided by 4 sections with 1/8 wavelength and 2 sections with 1/4 wavelength which have different line impedances. The characteristics of the proposed BPF were highly improved by using three stage ring resonator. The characteristic impedance values of each sections were obtained by Powell's least square algorithm where differentiations are not needed. The measured results showed a good agreement with the theoretical results as well as ADS simulation.

• Journal of Industrial Technology
• /
• v.26 no.A
• /
• pp.95-99
• /
• 2006

In this paper, we proposed the new wavelength tunable filter for wide tunability of fiber ring laser. The proposed filter consists of the cascaded connection of Fiber Reflection Mach-Zehnder Interferometer and Sagnac filter or of hybrid filter and Fiber Reflection Mach-Zehnder Interferometer. The simulation shows that the continuous tunable range of 50nm can be obtained and that more stable single mode operation of ring laser can be expected due to narrow FWHM. of filter spectrum.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.23 no.3
• /
• pp.261-272
• /
• 2005

3D models in urban areas are essential for a variety of applications, such as virtual visualization, GIS, and mobile communications. LIDAR (Light Detection and Ranging) is a relatively new technology for obtaining Digital Terrain Models (DTM) of the earth's surface since manual 3D data reconstruction is very costly and time consuming. In this paper an approach to extract ground and non-ground points data from LIDAR data by using filtering is presented and the accuracy for generating DTM from ground points data is evaluated. Numerous filter algorithms have been developed to date. To determine the performance of filtering, we selected three filters which are based on the concepts for height difference, slope, and morphology, and also were applied two different data acquired from high raised apartments areas and low house areas. From the results it has been found that the accuracy for generating DTM from LIDAR data are 0.16 m and 0.59 m in high raised apartments areas and low house areas respectively. We expect that LIDAR data is used to generate the accurate DTM in urban areas.

• The Journal of the Acoustical Society of Korea
• /
• v.7 no.4
• /
• pp.98-109
• /
• 1988

This paper introduces an adaptive nonlinear filtering algorithm that uses the sequential regression(SER) method to update the second order Volterra filter coefficients in a recursive way. Conventionally, the SER method has been used to invert large matrices which result from direct application of Wiener filter theory to the Volterra filter. However, the algorithm proposed in this paper uses the SER approach to update the least squares solution which is derived for Gaussian input signals. In such an algorithm, the size of the matrix to be inverted is smaller than that of conventional approaches, and hence the proposed method is computationally simpler than conventional nonlinear system identification techniques. Simulation results are presented to demonstrate the performance of the proposed algorithm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2018.11a
• /
• pp.55-58
• /
• 2018

본 논문에서는 가이디드 영상 필터를 (guided image filter) 이용하여 컨볼루션 신경망 (convolutional neural network) 을 이용한 역 톤 매핑 (inver tone - mapping; iTMO) 기법의 결과를 향상 시킬 수 있는 알고리듬을 제안한다. 기존 low dynamic range (LDR ) 영상을 high dynamic range (HDR ) 디스플레이에서 표현할 수 있는 역 톤 매핑 기법이 과거부터 계속 제안되어 왔다. 최근에 컨볼루션 신경망을 이용하여 단일 LDR 영상만으로 넓은 동적 범위 (dynamic range) 를 가진 HDR 영상으로 변환하는 알고리듬이 많이 연구되었다. 기존의 알고리듬 중 포화 영역 (saturated region) 으로 인해 잃어버린 화소 정보를 학습된 컨볼루션 신경망을 이용해서 복원하는 알고리듬은 그 효과가 좋지만 포화 영역이 아닌 부분의 잡음을 제거하지 못하며 포화 영역의 디테일을 복원하지 못한다. 제안한 알고리듬은 입력 영상에 가중치 기반 가이디드 영상 필터를 사용해서 비포화 영역의 잡음을 제거하고 포화 영역의 디테일을 복원시킨 다음 컨볼루션 신경망에 인가하여 결과 영상의 품질을 개선하였다. 제안하는 알고리듬은 실험을 통해서 기존의 알고리듬에 비해 높은 정량적 화질 평가 지수를 나타내었고, 기존의 알고리듬에 비해 세부 사항을 효과적으로 복원할 수 있음을 확인할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.2
• /
• pp.1-5
• /
• 2017

In this paper, we propose a wideband band-stop filter (BSF) in order to extend the stopband of the band-stop filter using a symmetric dual spurline and the coupled open stub. First, we know that the symmetric dual spurline structure is advantageous in widening the stopband, as compared to the asymmetric dual spurline structure. So we designed a band-stop filter that combines the electrically coupled open stub (ECOS) band-stop filter with a symmetric dual spurline. We can greatly extend the stopband, when it is combined with the dual spurline and electrically coupled open stub on a microstrip transmission line, without any size increment. The stopband of the proposed band-stop filter is extended by approximately 244% (rejection depth: -20 dB) compared with a band-stop filter without a dual spurline.

• The Journal of Engineering Geology
• /
• v.28 no.3
• /
• pp.465-473
• /
• 2018

The application of singular value decomposition (SVD) filtering is examined for attenuation of the ground-roll in land seismic data. Prior to the SVD computation to seek singular values containing the highly correlatable reflection energy, processing steps such as automatic gain control, elevation and refraction statics, NMO correction, and residual statics are performed to enhance the horizontal correlationships and continuities of reflections. Optimal parameters of SVD filtering are effectively chosen with diagnostic display of inverse NMO (INMO) corrected CSP (common shot point) gather. On the field data with dispersion of ground-roll overwhelmed, continuities of reflection events are much improved by SVD filtering than f-k filtering by eliminating the ground-roll with preserving the low-frequency reflections. This is well explained in the average amplitude spectra of the f-k and SVD filtered data. The reflectors including horizontal layer of the reservoir are much clearer on the stack section, with laminated events by SVD filtering and subsequent processing steps of spiking deconvolution and time-variant spectral whitening.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.8A
• /
• pp.796-804
• /
• 2002

This paper presents a new algorithm of fingerprint image analysis and processing using directional filter bank(DFB). The directional components of ridge is very important in pre-processing steps of fingerprint image processing such as image enhancement by directional filtering followed by estimationg the directional image of ridge patterns. The DFB analyzes input image into directional subband images and synthesizes them to the perfectly reconstructed image. In this paper, a new fingerprint processing algorithm using the DFB is proposed. The algorithm decomposes the fingerprint image into directional subband images and performs directional map generation, foreground segmentation, singular points extraction and image enhancement based on local directional energy estimate.

• The Journal of the Korea Contents Association
• /
• v.9 no.11
• /
• pp.309-315
• /
• 2009

Image reconstruction of Inverse Fourier Transform after Frequency Domain Data is filtered applies to Image signal acquired from MR. There are various kinds of image processing techniques; image preprocessing, image reconstruction, image compression, image restoration image mixture, noise and artifact elimination, and image quality improvement. In this paper, optimum filter applicable to diagnosis in clinic by comparing and analyzing the characteristics of the filter will be explained. Fermi-Dirac filter will improve the image quality better than the previous MR image.