디지털 信號의 實時間 處理

許道根 원광대학교 공업기술개발연구소 1981 工業技術開發硏究誌 Vol.1 No.-

This paper describes the algorithm that reduces the operation time of the digital signal processing and studies digital system which processes the digital signals in real time using this algorithm. As the studied results, the operation time enhances at 2.5~3.0 times than that of implementation of TTL I.C. Then we can change digital system characteristics without hardware changes.

디지털 필터의 설계와 구성 ( A DESIGN AND CONSTRUCTION OF DIGITAL FILTER )

허도근,진용옥,이대영 대한전자공학회 1980 대한전자공학회 학술대회 Vol.1980 No.1

문서 영상의 패턴 분리에 관한 연구

허도근 圓光大學校 1995 論文集 Vol.30 No.2

본 논문에서는 본문, 표, 사진으로 구성된 문서 영상의 패턴 분리와 문자 분리를 효과적으로 분리 해낼 수 있는 알고리즘을 제안한다. 패턴 분리 알고리즘은 이전 주사선과 현재 주사선에 존재하는 패턴 선분의 에지점을 받아들여 두 주사선 상에 존재하는 에지점의 위치를 좌에서 우로 순차적으로 비교하여 패턴의 최대, 최소 점의 좌표를 결정함으로서 패턴을 분리한다. 문자 분리는 패턴 분리과정에서 얻은 통계적 성질을 이용하여 임계값을 결정하여 패턴을 분리한다. 제안된 알고리즘에서 패턴은 한 주사선씩 행해질 수 있고, 문자 분리는 패턴 분리에서 얻은 파라메타를 사용하므로 처리시간을 향상시킬 수 있으며, 문자는 문서의 한줄에 존재하는 패턴의 임계값에 따라 분리되므로 문자의 크기나, 패턴의 크기에 관계없이 분리 가능하다. This paper proposes an efficient pattern and character segmentation algorithm for document images, which consist of text, tables, and photographs. The pattern segmentation algorithm accepts as input the edge point of the segment which exists on a previous and a current scan line. It decides the pattern by considering the segments from previous and current line from left to right sequences. The pattern region is segmented by maximum and minimum x-y coordinates. The character segmentation algorithm decides the threshold value of the pattern size using the parameter from the pattern segmentation, such as length of pattern and statistical distribution of the segmented pattern versus the length of pattern. It uses the threshold value to segment a character. In the proposed algorithm, the pattern segmentation of the image is performed by scan line-by-scan line, and may be undertaken while the document is being scanned during the input phase. The parameter for the character is also extracted during the this phase, so that the processing time for the proposed scheme is very short. The characters are segmented regardless of the character or pattern size because the threshold value is determined according to their size in document line.

데이타 通信의 過誤 檢出과 訂正

許道根 圓光大學校 1981 論文集 Vol.15 No.1

本 論文은 傳送線間의 干涉이나 誘導 現狀에 依하여 發生하는 過誤를 檢知하고 이것을 訂正하는 回路 構成에 對하여 論한다. 電子 計算機의 周邊 裝置의 데이터 通信에 效率的인 해밍 코우드(Hamming Code) 方法을 使用하였으며 傳送하고저 하는 情報와 過誤檢知 코우드를 傳送하고 受信器는 이들 데이터를 받아 傳送途中에 發生하는 過誤를 訂正하는 方法이다. 이 方法을 使用함으로서 傳送速度는 2/3 減少하였으나 過誤發生 確率은 1/100 程度 減少하였으므로 送受信 裝置의 信賴度를 增加시켰다. This paper describes realization of the detection and correction of the errors that etentially comes from the interference and the inductance between the transmission lines. Hamming code is used in order to transmit effectively the data to peripherls of the computer. Using Hamming code, the transmitter sends the imformation and code of error detection to a receiver and the receiver receives this data and corrects the errors that occurs during the transmission. As the results, the transmission velocity declines at 2/3 but the probability that errors occur declines at 1/100. The reliability of transmitter-receiver is improved.

CDMA 채널을 통한 영상 전송에 대한 연구

허도근,김용욱 한국통신학회 1997 한국통신학회논문지 Vol.22 No.11

This paper proposes a compression technique of image data, a variable length PN code and channel models which are required in CDMA communication system. It also analyzes their performances. Original images is compressed by 2-D DCT and its coefficients are quantized by optimal quantizer at compression rate 0.84bit/pel. Channel model 1 and 2 which are composed of 5 and 4 channels respectively are employed to be used in CDMA. Such a situation forces us to empoly variable length PN code, such as Chebyshev map for spread spectrum system. When average PN code length of model 1 and 2 is 44.4 and 26.7 chips respectively, the received image through these models under Gaussian noise with variance 1.75 is visually of the same quality as the transmitting image. Thus, the model 2 appears to be better in channel efficiency, comparing with channel model 1 and channel model which uses fixed length PN code.

EREC 기반의 계층적 적용과 양방향 탐색에 의한 에러 복원 향상

허도근,김태주 원광대학교 공업기술개발연구소 2001 工業技術開發硏究誌 Vol.21 No.-

Bit erros in variable length codes cause synchronization loss. Loss of block synchronization produces the worst image degradation. Even an error of a single bit in block synchronization may result in data to be placed in wrong positions by spatial shifts, Error resilient coding reduces the redundancy due to channel coding and yet protects against error propagation. The EREC(Error Resilient Enoogy Coding) algorithm increases resilience and provides graceful degradation of errors by reordering the variable length codes into fixed length slots of data. Although the EREC algorithm enhances error resilience immensely, it has two disadvantages of redundancy and computational efficiency. In this paper, in order to improve the conventional EREC algorithm, the hierarctlical synchronization techruque and the bi-directional search process to determine the offset are used. As a result, show the loss of block less and the value of PSNR more than the conventional EREC algorithm. In the speed-up of search stage of the effectively applied EREC algorithm over of the conventional EREC algorithm, it is observed to 1.5 ~ 2.0.

웨이브렛 패킷 변환을 이용한 대역 확산 코드에 관한 연구

허도근,정상연 원광대학교 공업기술개발연구소 1999 工業技術開發硏究誌 Vol.19 No.-

The recent commercial DS/SS CDMA, in which PN code is used as spreading code, accesses more users than FDMA or TDMA. As this system has 1.2288 Mchip/sec of long PN code, it takes long time for receiver to acquire and track PN code. A spreading code is proposed in this paper to resolve this problem. The proposed spreading code is designed by inverse wavelet packet transform of bin whose one element is 1 and others are 0. It has shown that correlation performance of the proposed spreading code is better than that of PN code and its BER is improved comparing with PN code. As its length is 1/8 of that of PN code and the effect of channel bandwidth is improved by 8 times of that of DS/SS CDMA.

컴퓨터를 利用한 디지탈 필터 設計

許道根 원광대학교 공업기술개발연구소 1984 工業技術開發硏究誌 Vol.4 No.-

This paper proposes the algorithm which designed the digital filter with computer aided design method for it to achieve a specified amplitude response. The program to execute this algorithm is listed to design 16-order digital filter with FORTRAN 77 language. The amplitude response of 2-order low pass digital filter which is designed by this program conforms to the specified amplitude response. This proposed algorithm is applicable without regard to a sort and order number of digital filter.

자소 분리에 의한 한글 인식에 관한 연구

허도근,심우성 원광대학교 공업기술개발연구소 1995 工業技術開發硏究誌 Vol.15 No.-

It is difficult for computer to recognize Hangul characters becauae they are composed of several letters and the letters are joined together in some characters. To recognize the characters, characters are classified as six types known as 6-type of Hangul, and letters of the classified characters are segmented according to 6-type of character, and the segmented letters are recognized using a neural network. The neural network for type classification and character recognition is constructed as multi-layer. Inputs of the neural network are 4-direction vectors which are extracted from the mesh of the normalized character. The neural network is learned by the training rule of back propagation and descending epsilon algorithm to increase the learning speed and classification rate in the character classification and is learned by the back propagation algorithm in the character recognition. The type of character is classified completely in 1-type and 2-type and classification errors occur in the other four types. The most of recognition errors occur in 5-type and 6-type. It has been shown that classification rate is 96.5% and recognition rate is 93.5%.

트렐리스의 제로 상태 종료를 위한 가변 종료 인터리버

허도근,김용욱 원광대학교 공업기술개발연구소 2000 工業技術開發硏究誌 Vol.20 No.-

As the final state of the constructional encoder of Turbo code is different due to the feedback property of RSC(recursive systematic convolution) code and the existence of interleaver, in order to terminate Trellis in zero states, tail bits are required as many as the number of the memory of each encoders and the constructional Trellis is terminated separately Therefore, in this thesis, a variable termination interleaver, capable of terminating Trellis of two constructional encoders in zero states at the same time only with the tail bits as many as the number of memories terminating the first constructional encoder in zero states and handling variable frame such as interleavers recommended in IMT-2000 Standard, is proposed and then the properties are evaluated as compared to the conventional self-termination interleavers in sizes of frames.