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디저화 영상의 다치추정을 이용한 중간조 영상의 단계적 전송에 관한 연구
김신환,이용두,황병원 한국통신학회 1990 韓國通信學會論文誌 Vol.15 No.9
디저법은 2치 영상이지만 인간 시각의 적분 효과에 의해 濃淡이 있는 영상처럼 보이게 하는 방법으로 위치에 따라 값이 다른 문턱값과 濃淡이 있는 영상의 화소값을 비교하여 화소값이 문턱값보다 크면 흰색(on), 작으면 검은색(off)으로 결정하는 수법이다. 본 논문에서는 디저영상으로부터 濃淡영상을 추정하는 새로운 다치추정법을 제안하여 그 결과가 종래의 방법보다 약 0.7dB 개선되었음을 보이고, 이 방법을 사용하여 영상의 새로운 단계적 전송 방법을 제안한다. This paper presents a new method of multilevel estimation of dithered images. A dithered picture, a two-tone picture which gives the illusion of picture with many shades of gray, is obtained by comparing the gray-level picture which gives the illusion of picture with a position-dependent threshold. When the intensity of a picture element exeeds the threshold it is classified as white: otherwise it is black. In the new estimation scheme, the simulation results show the SNR of the new method is improved 0.7dB compared with the old method. And we propose a new progressive image transmission by employing thie method.
광 회절 초음파 공명법에 의한 methyl acetate의 cis-trans의 회전이성 완화의 연구
김신환,배종림 大邱大學校附設 基礎科學硏究所 1998 基礎科學硏究 Vol.15 No.2
Ultrasonic absorption measurements in methyl acetate have been carried out over the frequency range 0.1 - 10 MHz at temperature of 5-30℃ using a high-Q ultrasonic resonator method using optical diffraction which is useful for ultrasonic relaxation around 1 MHz. The results showed a typical spectrum of a single relaxation process, from which the relaxation frequency was determined. The temperature dependence of relaxation frequency gives the activation enthalpy(ΔH^(#)) between axial and equatorial isomers of methyl acetate, which are ΔH^(#)=6.6 kcal/mol.
김신환,문병현 대구대학교 과학기술연구소 1998 科學技術硏究 Vol.5 No.4
The hierarchical transmission of an image is proposed that has advantages in that the overall information of the image can be extracted in the initial transmission stage as well as in that a high resolution image can be constructed if the transmission is completed by the final stage. Instead of the coder suggested by Burt, this paper constructs a new coder, shows the excellency of the suggested coder by experiment, and adapts the closing-opening filter in the hierarchical scale-down stage of the Pyramid to show the superiority of the suggested closing-opening filter to a simple opening filter.