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화자인식을 위한 음성 요소들의 성능분석 및 새로운 판단 논리
이혁재,이병기,Lee, Hyuk-Jae,Lee, Byeong-Gi 대한전자공학회 1989 전자공학회논문지 Vol. No.
본 논문에서는 화자인식 시스템의 인식율 향상을 도모하기 위하여 요소의 선택 및 판단 논리의 문제를 고찰하였다. 또한 화자인식 실험을 수행하는 과정에서 기준패턴의 작성이 인식율에 어떠한 영향을 미치는 가를 아울러 검토해 보았다. LPC, PARCOR 계수, LPC-cepstrum 계수등을 인식 요소로 사용하여 화자확인 오차율을 측정한 결과, 기준 패턴의 작성방법에 관계 없이 LPC-cepstrum계수의 성능이 LPC나 PARCOR 계수의 성능에 비해 우수한 것으로 나타났다. 또 화자인식율을 향상시키기 위하여 일반화된 거리 개념을 도입한 새로운 판단 논리를 제안하였다. 제안된 판단 논리는 기준화자 및 외부화자의 통계적 성질을 동시에 고려하여 각 요소들에 서로 다른 가중치를 둔다는 점이 기존의 방법들에 비해 다르다. 화자적인 실험결과 제안된 판단 논리를 적용한 경우가 기존의 방법들에 비해서 인식율이 향상된 것을 관찰할 수 있었다. This paper discusses how to choose speech parameters and decision logics to improve the performance of speaker recognition systems. It also considers the influence of the reference patterns on the speaker recognition. It is observed from the performance analysis based on LPSs, PARCOR coefficients and LPC-cepstrum coefficients that LPC-cepstrum coefficients are superior to the others in speaker recognition without regard to the reference patterns. In order to improve the recognition performance, a new decision logic is proposed based on a generalized-distance concept. It differs from the existing methods in that it considers the statistics of customer and impostors at the same time. It turns out from a speaker verification test that the proposed decision logic ferforms better than the existing ones.
이혁재,Jun-Ho Shin,Jisu Chae,Jung Bin Kim,김태희,박경봉 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.3
A ZnO seed layer is prepared from ZnO sol under various heating conditions, whose effect on the growth of ZnO nanorod arrays for the photoanode in dye-sensitized solar cells (DSSCs) is systematically investigated. Differential thermal analysis and x-ray diffraction investigation show that a pre-calcination temperature of at least 250°C is needed for the crystallization of the ZnO seed layer. Extreme preferential orientation along the (002) plane is also observed at 250°C. The post-annealing temperature governs the diameter and length of the vertically grown ZnO nanorod arrays. The diameter and length of the ZnO nanorod arrays increase till the post-annealing temperature reaches 500°C. At 600°C, the ZnO nanorod becomes shorter than that at 500°C. The longer and well-aligned ZnO nanorod arrays yield better photovoltaic performance. The optimum heating conditions to obtain the best conversion efficiency of DSSCs are found to be pre-calcination at 250°C and post-annealing at 500°C.
Magnetism of a System Interacting with a Common Environment
이혁재,이석,김재헌 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.6
We consider a system and environment governed by the Markovian process. The density matrix (the reduced density matrix) of the system satisfies the Kossakowski-Lindblad equation. We calculate the expectation value of the z-direction-magnetization in the system for various types of initial states and interactions between the system and environment. In all the cases, the values of the magnetization approached asymptotically to the same value in spite of the different initial states. However, according to the different interaction types between the system and the environment, the asymptotic values are different according to the initial states.