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색분산 보상을 위한 선형 첩 광섬유 격자의 Apodization
박제형,최선민,한영근,김상혁,이상배 한국광학회 2004 한국광학회지 Vol.15 No.3
색분산 보상에 사용되는 선형 첩 광섬유 격자의 제작에 있어서 Group Delay Ripple(GDR)을 줄이기 위한 apodization 기술에 대해 이론적으로 분석하고 실험적으로 규명하고자 한다. 첩격자의 제작에는 위상 마스크를 이용한 UV 빔 스캐닝 기법을 적용하였고, PZT(Piezoelectric transducer)를 이용하여 위상 마스크를 빔 스캐닝 중에 적절하게 흔들어줌으로써 apodization이 일어나도록 하였다. 이러한 모든 과정이 컴퓨터 제어로 이루어지기 때문에 다양한 apodization 프로파일을 적용할 수 있었다. Gaussian, Raised-cosine, Blackman, 그리고 Hyperbolic tangent 등의 프로파일을 적용하여 첩격자를 제작하였으며 실험 결과 0.05 nm 구간평균 peak-to-peak GDR이 20ps 이하로 감소하였다. We theoretically and experimentally investigate the effect of apodization on the transmission characteristics of linearly chirped fiber Bragg gratings(CFBGs). Based on the UV beam scanning method along a phase mask, we fabricated several apodized CFBGs with different apodization profiles such as Gaussian, Raised-cosine, Blackman, and Hyperbolic tangent. During the UV beam scanning, the phase mask is dithered by a PZT(Piezoelectric transducer) which is precisely controlled by a computer program so that the apodization profiles can be flexibly applied to the grating. We measured the reflection spectra and group delay characteristics of CFBGs with the different apodization profiles, and compared them according to their properties such as reflectivity, sidelobes, and group delay ripple (GDR). The peak-to-peak of GDR could be suppressed to less than 20 ps.
TiB2 나노입장의 연소합성 시 MgO 희석제가 미치는 영향
박제형,김도경,이병기,이종무,강을손,백승수 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.9
The effect of MgO diluent in combustion synthesis of TiB2 nano particles was investigated. The reaction TiO2 + B2O3 + xMg → TiB2 + 5MgOwas used to synthesize TiB2 nano particles. The combustion velocity was measured to examine the relation between the reaction temperature and the morphologies of particles. The diluents MgO did not react with the reactants and played a role to decrease combustion temperature. As the MgO diluents contents increased, the particles with the smaller size and the narrower size distribution were synthesized. At the condition of 6 mole of MgO, the combustion wave velocity was about 5 cm/sec and the synthesized particles showed the size of 60 nm with narrow size distribution.
TiB<sub>2</sub> 나노 입자의 연소합성 시 MgO 희석제가 미치는 영향
이병기,이종무,박제형,강을손,백승수,김도경,Lee, Byung-Ki,Lee, Jong-Moo,Park, Je-Hyeong,Kang, Eul-Son,Baek, Seung-Soo,Kim, Do-Kyung 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.9
The effect of MgO diluents in combustion synthesis of $TiB_2$ nano particles was investigated. The reaction $TiO_2\;+\;B_2O_3\;+\;xMg\;{\rightarrow}\;TiB_2\;+\;5MgO$ was used to synthesize $TiB_2$ nano particles. The combustion velocity was measured to examine the relation between the reaction temperature and the morphologies of particles. The diluent MgO did not react with the reactants and played a role to decrease combustion temperature. As the MgO diluents contents increased, the particles with the smaller size and the narrower size distribution were synthesized. At the condition of 6 mole of MgO, the combustion wave velocity was about 5 cm/see and the synthesized particles showed the size of 60 nm with narrow size distribution.
주찬웅,김민선,박제형 대한심장학회 2005 Korean Circulation Journal Vol.35 No.12
We report here on a previously healthy 5-year-old girl with significant electrocardiographic repolarization abnormalitiesand a left ventricular mass. After the clinical evaluation, a large muscular false tendon was found withinthe left ventricular cavity.