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Noise Shaping Based on Psychoacoustic Model
Lee, Jingeol,Nam, Seung Hyon The Acoustical Society of Korea 2001 韓國音響學會誌 Vol.20 No.e2
A psychoacoustic model based noise shaping method which shapes the noise in the frequency domain is proposed, where its presence with a host signal will not be perceptually noticeable. The derivation of imperceptible noise levels from the masking thresholds of the signal involves a deconvolution associated with the spreading function in the psychoacoustic model, which results in an ill-conditioned problem. In this paper, the problem is formulated as a constrained optimization, and it is demonstrated that the solution provides noise shaping where the noise excitation level conforms to the masking thresholds of the signal, and thus the noises embedded in the signal will not be perceived by human ear.
Velocity Measurement of Granular Flow with High Speed Digital Images
Jingeol Lee 한국정보과학회 1998 Journal of Electrical Engineering and Information Vol.3 No.4
The flow of granular materials is common to many industrial processes. This paper discusses a methodology which utilizes high speed digital imaging to measure velocity of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in our experiment. One technique utilizes block matching for spatially averaged velocity measurements of the glass particles. Another technique for measuring the velocities of individual acrylic particles is developed with correspondence using the Hopfield network. This latter technique first locates the positions of particles with variance normalized correlation as a pattern recognition technique, followed by a clustering technique, which produces point patterns. Then, correspondence between successive point patterns is solved by a Hopfield network for the velocity measurements of individual particles. The velocity measurements are refined to the subpixel resolution by the variance normalized correlation with interpolation in both techniques.
Speech Enhancement Based on Psychoacoustic Model
Lee, Jingeol,Kim, Soowon The Acoustical Society of Korea 2000 韓國音響學會誌 Vol.19 No.e3
Psychoacoustic model based methods have recently been introduced in order to enhance speech signals corrupted by ambient noise. In particular, the perceptual filter is analytically derived where the frequency content of the input noisy signal is made the same as that of the estimated clean signal in auditory domain. However, the analytical derivation should rely on the deconvolution associated with the spreading function in the psychoacoustic model, which results in an ill-conditioned problem. In order to cope with the problem associated with the deconvolution, we propose a novel psychoacoustic model based speech enhancement filter whose principle is the same as the perceptual filter, however the filter is derived by a constrained optimization which provides solutions to the ill-conditioned problem. It is demonstrated with artificially generated signals that the proposed filter operates according to the principle. It is shown that superior performance results from the proposed filter over the perceptual filter provided that a clean speech signal is separable from noise.
Transmission Line Based Plucked String Model
이진걸,Lee, Jingeol,French, Mark The Acoustical Society of Korea 2013 韓國音響學會誌 Vol.32 No.4
진동하는 현의 성질을 나타내는 방법으로 반대 방향으로 진행하는 파가 현과 전송선로에 존재한다는 사실에 기초하여 현은 전송선로에 비유되어왔다. 이러한 비유에서 현의 강역(rigid end)과 변위는 각각 전송선로의 개방회로와 전류로 나타내어졌다. 그러나, 본 연구에서 강역과 변위는 각각 단락회로와 전압에 해당됨이 전송선로의 이론으로부터 밝혀졌고 이를 회로시뮬레이션으로 확인하였다. 이러한 발견에 기초하여 전송선로, 구분적 선형 전류원, 스위치들로 구성된 전송선로 기반 탄현 모델을 제안하였다. 임의로 선택된 지점에서의 전압과 전송선로 끝 극소 부분 양단에서 계산된 전압이 현의 성질을 지배하는 파동방정식의 차분형식(difference form)으로 구한 해당 지점에서 변위와 강역에서의 힘과 일치함을 보임으로서 제안한 모델이 정당함을 증명하였다. 또한, 제안된 모델의 현악기 및 관악기 모델링의 적용성을 제시하였다. As one way to describe the behavior of a vibrating string, analogies to a transmission line have been made based on the fact that they have oppositely travelling waves on each of them. In such analogies, a rigid end to the string has been represented as an open circuit, and the displacement of the string as the current on the transmission line. However it turns out that the rigid end corresponds to a short circuit, the displacement to the voltage by the theory of the transmission line, and it is confirmed by experiments with circuit simulations. Based on these discoveries, a transmission line based plucked string model comprising a transmission line, two piecewise linear current sources, and switches is proposed. The proposed model is validated by showing that the voltage at the arbitrarily chosen location, and the voltage calculated over an infinitesimal portion at the end of the transmission line are consistent with the displacement at the corresponding location and the force on the rigid end of the string from the well known difference form of a wave equation governing the behavior of the string with its fundamental frequency tuned to that for the proposed model, respectively. Moreover, the applicability of the proposed model to modeling string and wind instruments is presented.
이진걸,이규봉,황상기,Lee Jingeol,Lee Gyoubong,Hwang Sang-Gi 한국전기전자학회 1999 전기전자학회논문지 Vol.3 No.2
위성사진에서 선구조의 형태로 인식 및 해석되는 단층 및 단열대 구조와 같은 지질구조는 광산지역의 사전탐사나 지질학적 특성에 관한 중요한 정보를 제공한다. 선구조의 방향이 태양의 방위각과 평행하거나 지형의 고저에 의한 그림자가 드리워지는 등의 이유로 해서 명암의 대비가 낮은 지역의 선구조를 효과적으로 추출하기 위한 태양방위각을 고려한 필터링 방법 및 Generalized Hough transform을 이용하여 필터링에 의해 추출된 경계영상으로부터 단층 및 단열대에 대응하는 선구조를 추출하는 방법이 제안되었다. Geological structures such as fault and fracture patterns provide important information about preliminary exploration of mineralized areas and geological characterization. They may be recognized and interpreted from satellite images as line-like features usually referred to as lineaments. A proposed filtering method taking the sums azimuth angle into account is utilized, by which linear edges from low contrast areas where features extend parallel to the sun direction and in mountain shadow can be effectively extracted. Then, generalized Hough transform is applied to extract lineaments which correspond to fault and fracture patterns.