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순환 DFT 기반의 동기 위상 측정에 있어서 계수 근사에 따른 성능 열화 분석
김종윤,장태규,Kim, Chong-Yun,Chang, Tae-Gyu 대한전자공학회 2002 電子工學會論文誌-SP (Signal processing) Vol.39 No.4
본 논문에서는 순환 DFT 기반의 위상 측정 알고리즘을 구현함에 있어서 계수 근사 및 주파수 변이에 따른 성능 열화를 해석하였다. 오차의 영향을 해석하기 위해서 근사 순환 DFT식을 이용하여 오차 방정식(error dynamics)을 정의하고 이의 통계적 특성을 이용하여 오차의 특성을 분석한다. 오차 전력은 오차파급의 주요 영향 요소인 근사 bit수, DFT 구간 길이와 잡음에 관한 closed-form으로 유도되어 진다. 해석적으로 유도한 식과 시뮬레이션 실험을 통해 얻을 결과를 비교하여 타당성을 확인하였다. This paper presents an analysis of the performance degradation of coefficient approximation and frequency deviation in phase measurement algorithm based on Sliding-DFT. The analytic derivation is based on the statistics of the error dynamic equation that describes the error propagation of the recursion. The analysis result is intended to obtain a closed-form equation of error variance in terms of the number of bits used in coefficient approximation, the length of the DFT data block, and noise. It is verified with data obtained from the computer simulations.
백반증 치료에 있어서 narrow - band UVB 의 효과
김종윤(Chong Yun Kim),윤미라(Mi Ra Youn),유정환,박욱화(Wook Hwa Park) 대한피부과학회 2002 大韓皮膚科學會誌 Vol.40 No.7
N/A Background : Many modalities of treatment for vitiligo have been elucidated and yet the treatment of vitiligo remains to be a challenge. Objectives : The purpose of this article is to review our results and experiences with narrow-band ultraviolet B phototherapy for vitiligo. Method : We studied 9 patients with vitiligo who received narrow band UVB phototherapy for 6 months in our department. This is a retrospective analysis of our experiences and results. Results : Nine patients were able to be evaluated for the purpose of this analysis. Their ages ranged from 6 to 68 years(mean, 18.4 years). Six patients of 9 patients achieved more than 75% repigmentation with a mean of 25 sessions of phototherapy. The remaining three patients had 50%, 40% and 30% repig entation after 44, 40, and 45 sessions of phototherapy, respectively. Adverse effects were mild. Conclusion : Narrow-band UVB is a useful and well-tolerated therapy for vitiligo in comparsion with other therapies.