입방정계금속 (立方晶系金屬) 에 있어서 섬유 및 압연집합조직의 정량표현 : 2. 섬유집합조직

이창영,김순철,전병칠,김혜준 대한금속재료학회(대한금속학회) 1984 대한금속·재료학회지 Vol.22 No.3

In this second paper the fiber texture is dealt with. Experimental pole figures of iron and copper wires obtained by neutron diffraction method were analyzed using the computer program TXFIB to test analytical accuracies of Bunge's method. For samples of widely differing texture sharpness, Jo=0.005∼0.78, analytical errors and R factors resulted from various number of input data and degree of series expansion are compared and results are discussed. And, observed features of hot-and cold-drawn textures and some recrystalization textures of the samples are summarized.

초고속 자기부상열차 적용을 위한 초전도 하이브리드 전자석 시작품의 설계

이창영,강부병,조정민,한영재,주승열,황영진,조현철,장재영,고태국 한국초전도저온학회 (구 한국초전도저온공학회) 2011 한국초전도저온공학회논문지 Vol.13 No.3

임펄스 잡음 환경에서 추정 마스크를 이용한 에지 검출 알고리즘에 관한 연구

이창영,김남호,Lee, Chang-Young,Kim, Nam-Ho 한국정보통신학회 2014 한국정보통신학회논문지 Vol.18 No.9

For edge detection methods, there are Sobel, Prewitt, Roberts and Canny edge detector, and these methods have insufficient detection characteristics in the image corrupted by the impulse noise. Therefore in this paper, in order to improve these disadvantages of the previous methods and to effectively detect the edge in the impulse noise environment, using the $5{\times}5$ mask, the noise factors within the $3{\times}3$ mask based on the central pixel is determined, and depending on its status, for noise-free it is processed as is, and if noise is found, by obtaining the estimated mask using the adjacent pixels of each factor, an algorithm that detects the edge is proposed.

저조도 환경에서 화소의 휘도 변환 함수를 이용한 에지 검출에 관한 연구

이창영,김남호,Lee, Chang-Young,Kim, Nam-Ho 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.7

Edge detection is an essential preprocessing for most image processing application, and there are several existing detection methods such as Sobel, Roberts, Laplacian, LoG(Laplacian of Gaussian) operators, etc. Those existing edge detection methods have not given satisfactory results since they do not offer enough pixel brightness change in low light level environment. Therefore, in this study new algorithms using brightness transfer function in the preprocessing and for edge detection applying standard deviation and average-weighted local masks are proposed. In addition, the performance of proposed algorithms was evaluated in comparison with the existing edge detection methods such as Sobel, Roberts, Prewitt, Laplacian, LoG operators.

모폴로지를 이용한 마스크 기반 에지 검출 알고리즘에 관한 연구

이창영,김남호,Lee, Chang-Young,Kim, Nam-Ho 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.10

디지털 정보화 시대에서 영상은 여러 매체에서 필수적으로 이용되며, 에지는 영상에서 물체의 크기, 위치, 방향 등을 포함하는 중요한 특징 정보이다. 이러한 에지를 검출하기 위한 여러 연구들이 국내외에서 진행되고 있다. 기존의 에지 검출 방법들에는 고정된 가중치 값을 적용하는 Sobel, Prewitt, Roberts, Laplacian, LoG 등이 있다. 이와 같은 기존의 에지 검출 방법들은 고정된 가중치 마스크를 영상에 적용하기 때문에 에지 검출 특성이 다소 미흡하게 나타난다. 따라서 본 연구에서는 이러한 문제점을 보완하기 위해, 모폴로지에서 bottom-hat 변환과 열기 연산을 이용하여 영상을 개선하고 마스크 기반의 기울기를 구한 후 에지를 구하는 알고리즘을 제안하였다. 그리고 제안한 알고리즘의 성능을 평가하기 위해, 기존의 Sobel, Roberts, Prewitt, Laplacian, LoG 에지 검출 방법들과 비교하여 시각적 영상을 나타내었고, 각각의 영상을 기준으로 하는 MSE 값을 구하여 유사성을 비교하였다.

그레이 레벨 변환 함수를 이용한 에지 검출에 관한 연구

이창영,김남호,Lee, Chang-Young,Kim, Nam-Ho 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.12

Edge detection is one of image processing techniques applied for a variety of purposes in a number of areas and it is used as a necessary pretreatment process in most applications. Detect this edge has been conducted in various fields at domestic and international. In the conventional edge detection methods, there are Sobel, Prewitt, Roberts and LoG, etc using a fixed weights mask. Since conventional edge detection methods apply the images to the fixed weights mask, the edge detection characteristics appear somewhat insufficient. Therefore in this study, to complement this, preprocessing using gray-level transformation function and algorithm finding final edge using maximum and minimum value of estimated mask by local mask are proposed. And in order to assess the performance of proposed algorithm, it was compared with a conventional Sobel, Roberts, Prewitt and LoG edge detection methods.

Model-free Analysis of the AC Susceptibility Harmonics by using the Relaxation Time Constant

이창영 한국물리학회 2011 새물리 Vol.61 No.4

By introducing of a relaxation time constant, we studied the ac magnetic susceptibility harmonics from superconductors. With no assumptions made or models specified, expressions for the ac susceptibility harmonics were derived, from which some interesting features, including harmonics-related symmetry properties, were deduced. The reason for the relative weakness and the condition for the vanishing of the even harmonics are explained. The relation between the in-phase and the out-of-phase ac susceptibilities is also obtained. The result provides an explanation for the susceptibility curves as functions of temperature near the phase transition. Our approach is unique in that all the results are obtained without invoking any specific physical models.

Extraction of Information Dimensions for Phonemes and Its Application to Speech Detection & Segmentation

이창영 한국물리학회 2013 새물리 Vol.63 No.7

As an application of dimensional analysis in the field of chaos and fractals, we estimate information dimensions for speech phonemes. By constructing phase space vectors from the time-series data of speech signals, we calculate the natural measure and Shannon's information. The information dimension is then obtained as the slope in the plot of the information versus space division order. A notable feature of the result is the drastic change in the information dimension at the onset of speech production. We expect that the information dimension might be utilized as a valuable tool for speech detection and segmentation.

윈도우가 적용된 자기상관에 의한 선형예측부호의 개선

이창영,이채봉 한국전자통신학회 2011 한국전자통신학회 논문지 Vol.6 No.2

In this paper, we propose a new procedure for improvement of the linear predictive coding. To reduce the error power incurred by the coding, we interchanged the order of the two procedures of windowing on the signal and linear prediction. This scheme corresponds to LPC extraction with windowed autocorrelation. The proposed method requires more calculational time because it necessitates matrix inversion on more parameters than the conventional technique where an efficient Levinson-Durbin recursive procedure is applicable with smaller parameters. Experimental test over various speech phonemes showed, however, that our procedure yields about 5% less power distortion compared to the conventional technique. Consequently, the proposed method in this paper is thought to be preferable to the conventional technique as far as the fidelity is concerned. In a separate study of speaker-dependent speech recognition test for 50 isolated words pronounced by 40 people, our approach yielded better performance too. 본 논문은 선형예측부호의 개선을 위한 새로운 과정을 제안한다. 코딩에 따른 오차를 줄이기 위하여, 신호에 윈도우를 적용하는 과정과 선형예측 과정의 순서를 바꾸었다. 이 처방은 윈도우를 적용한 자기상관을 이용하여 선형예측부호를 추출하는 것에 해당한다. 기존의 방법에서는 보다 적은 파라미터에 대해 레빈슨-더빈의 재귀적 계산법을 적용하는 것이 가능한 반면, 본 논문에서 제안된 방법에서는 더 많은 작업 파라미터에 대한 역행렬 계산이 필요하므로, 보다 긴 계산 시간이 요구된다. 하지만, 여러 음성 음소에 대해 테스트한 결과, 제안된 방법에 의하면 기존의 기술에 비해 약 5% 적은 파워 왜곡이 얻어짐이 밝혀졌다. 따라서 부호화의 신뢰성에 관한 한, 기존의 기술에 비해 본 논문에서 제안된 방법이 더 나은 것으로 사료된다. 40명에 의해 발성된 50 고립단어에 대한 화자종속 음성인식 시험에서도 제안된 방법이 보다 우수한 성능을 보여주었다.

음성인식에서 중복성의 저감에 대한 연구

이창영 한국전자통신학회 2012 한국전자통신학회 논문지 Vol.7 No.3

The characteristic features of speech signal do not vary significantly from frame to frame. Therefore, it is advisable to reduce the redundancy involved in the similar feature vectors. The objective of this paper is to search for the optimal condition of minimum redundancy and maximum relevancy of the speech feature vectors in speech recognition. For this purpose, we realize redundancy reduction by way of a vigilance parameter and investigate the resultant effect on the speaker-independent speech recognition of isolated words by using FVQ/HMM. Experimental results showed that the number of feature vectors might be reduced by 30% without deteriorating the speech recognition accuracy.