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포토리프랙티브 결정 내의 두빔 에너지 결합에서의 Bragg 회절
김재동,김주엽,이연호 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2
In this paper we employ a new method to derive Bragg diffraction from a photorefractive grating without four - wave mixing geometry. In this calculation we assume two - beam energy coupling in a photorefractive crystal to occur due to Bragg diffraction of two incident beams from a photorefractive grating. At a steady - state of two - beam energy coupling we have obtained Bragg diffraction of the incident beams, which corresponds to Bragg diffraction of any incident beam, or a third probe beam. It is shown that our result predicts exactly the same Bragg diffraction as the coupled wave equations of four- wave mixing, and that the diffraction effciency strongly depends on two - beam coupling gain. It is also shown that our result is given by a form much simpler than its counterpart.
배전용변압기의 소음저감을 위한 진동주파수의 스펙트럼분석
김재철,이현구,송승엽,이도훈 崇實大學校 生産技術硏究所 2002 論文集 Vol.32 No.-
This paper analyze spectrum of vibration-frequencies to reduce noise level of d transformer. Using loading back method on same condition of real load to grasp th core and winding which are caused by the transformer vibration. We were mea vibration-frequency by varing appiled voltage and load current of a transformer. cause of a transformer vibration is occured by the harmonic effects, and was identifi vibration is less influenced by the coil. As the result of this paper, comparing the transformer with some isolated materi general transformer, the transformer with some isolated material could reduc amplitude of vibration-frequencies.
Kim, Hee Man,Park, Jeong Youp,Kim, Kyung Sik,Park, Mi-Suk,Kim, Myeong-Jin,Park, Young Nyun,Bang, Seungmin,Song, Si Young,Chung, Jae Bock,Park, Seung Woo Blackwell Publishing Asia 2010 Journal of gastroenterology and hepatology Vol.25 No.2
<P>Abstract</P><P>Background and Aim: </P><P>In hilar cholangiocarcinoma, an accurate assessment of preoperative resectability is important to optimize surgical resection. We investigated the accuracy of the combination of intraductal ultrasonography (IDUS) and percutaneous transhepatic cholangioscopy (PTCS) for evaluating longitudinal extent in hilar cholangiocarcinoma.</P><P>Methods: </P><P>Patients diagnosed with hilar cholangiocarcinoma underwent multidetector computed tomography (MDCT) and magnetic resonance cholangiography (MRC) for tumor staging and Bismuth type. Percutaneous transhepatic biliary drainage was performed at the left or right bile duct of the liver section that was anticipated to be preserved in the surgical treatment. After tract dilation, PTCS with cholangioscope-directed biopsy and IDUS were sequentially performed to evaluate Bismuth type. Surgical treatment was executed according to tumor staging and longitudinal tumor extent. Postoperative histological Bismuth types were compared to preoperative Bismuth types based on MDCT, MRC, PTCS with biopsy, and IDUS.</P><P>Results: </P><P>From June 2006 to November 2008, 25 patients with hilar cholangiocarcinoma were enrolled, with 20 of these patients evaluable. The accuracy of MDCT, MRC, PTCS with biopsy, and IDUS for the evaluation of Bismuth type was 80%, 84.2%, 90%, and 85.0%, respectively, in 20 patients, and 82.4%, 82.4%, 94.1%, and 88.2%, respectively, in 18 patients with Bismuth type IIIa, IIIb, or IV cancer. The accuracy of the combination of IDUS and PTCS with biopsy was 95% in 20 patients, and 100% in 18 with Bismuth type IIIa, IIIb, or IV cancer.</P><P>Conclusions: </P><P>The combination of IDUS and PTCS with biopsy was highly accurate for assessing Bismuth type and may help in the identification of an optimal surgical plan for the treatment of hilar cholangiocarcinoma, especially in Bismuth type IIIa, IIIb, or IV. </P>