http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
권오장,김선덕,윤민석,한영근 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9
We demonstrate a spectral-domian optical coherence tomography (SD-OCT) with a high axial resolution and a high speed of image acquisition using a broadband coupler based on a photonic crystal fiber (PCF). The PCF-based coupler with broad bandwidth is fabricated by using a fused biconical tapered (FBT) method and the axial resolution of the SD-OCT is improved to be 2 mm. The image acquisition speed of the SD-OCT is estimated to be 500 Hz. A k-domain linearization method is exploited to compensate mismatched spectral information between the wave-number and the pixel position at the CCD, which is induced by the nonlinearity of a diffraction grating plate.
렌즈형 광섬유를 이용하여 펄스형 반도체 레이저 Beam Shaping 및 증폭 기술 연구
권오장,김륜경,심영보,한영근,Kwon, Oh-Jang,Kim, Ryun-Kyung,Shim, Young-Bo,Han, Young-Geun 한국광학회 2010 한국광학회지 Vol.21 No.6
타원형 모양의 모드 형태를 갖는 펄스형 레이저 다이오드 (laser diode)의 펄스 형태를 유지하면서 단일 모드 및 Gaussian 형태로 광 모드 변환을 유도하고 광출력을 증폭할 수 있는 기술에 대해서 연구하였다. 실험에서 사용한 펼스형 레이저 다이오드의 구경이 가로는 $300{\mu}m$이며, 세로는 $2{\mu}m$이고 출력은 $1.1mW/cm^2$이다. 렌즈형 광섬유를 사용하여 광결합을 유도하여 단일 모드 및 Gaussian 형태의 출력으로 변환시켰다. 그러나, 다중모드의 펄스형 레이저 다이오드의 출력을 단일모드 렌즈형 광섬유에 결합시키면 출력이 급격하게 감소한다. 따라서 master oscillator power amplifier (MOPA) 기반의 광증폭 기술을 이용하여 레이저 다이오드의 광출력을 증폭시켰다. 증폭 후에도 펄스 성질은 그대로 유지되었고, MOPA구조를 지나 증폭된 광 출력은 $29mW/cm^2$로 측정되었다. We investigate an optical technique for beam shaping and optical amplification of a pulsed laser diode without variation of its original properties, such as repetition rate and pulse duration. The horizontal and longitudinal sizes of the pulsed laser diode are 300 and $2{\mu}m$, respectively, and its output power is $1.1mW/cm^2$. The multimodal and elliptical pulse shape of the laser diode is converted to the single-modal and Gaussian pulse shape by using a lensed optical fiber. Since the single-modal lensed fiber coupling from the multimodal pulsed laser diode degrades the output power severely, the output power of the pulsed laser diode is dramatically enhanced by using an optical amplification method based on master oscillated power amplification (MOPA). The pulse qualities of the laser diode are not changed after amplifying the pulse power and the output power was finally measured to be $29mW/cm^2$.
권오장,이재관,장범석,엄흥식,Kwon, Oh-Jang,Lee, Jae-Kwan,Chang, Beom-Seok,Um, Heung-Sik 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.1
Purpose: The purpose of this study was to investigate the incidence of curet fracture and its contributing factors. Material and Methods: Fifty-eight periodontal curets which were broken during periodontal treatment in Kangnung National University Dental Hospital for 1 year were used as study materials. The blade thickness of new curets and broken ones was measured using a digital micrometer. Types of treatment procedures, clinical experience of operators, point of breakage, and method of removal of broken fragments were recorded for each broken curet. Results: The incidence of curet fracture in root planing (16.4 curets per 1,000 procedures) was higher than those in flap surgery (7.5) or supragingival scaling (2.7). No curet was broken during supportive periodontal treatment. The incidence of fracture did not seem to be related with clinical experience of operators. The most frequent breakage point of the curets were upper 1/3 of blades. Fifty-six of 58 broken fragments were removed by non-surgical methods. Two broken tips which could not removed non-surgically were left in the pockets, and proved to be removed spontaneously 1 week later. Conclusion: Root planing showed higher incidence of curet fracture than any other type of periodontal treatment. Most of the fractured fragments were removed by non-surgical method. Further study is needed to develop methods of removal of the fragments which can not be removed non-surgically.
대장 선종 환자와 정상인에서 혈중 렙틴 농도와 대장 점막 렙틴 발현과의 상관관계
오장석 ( Jang Seok Oh ),김현희 ( Hyun Hee Kim ),황현식 ( Hyun Sik Hwang ),윤대영 ( Dae Young Yun ),김병석 ( Byung Seok Kim ),이창형 ( Chang Hyeong Lee ),한지민 ( Ji Min Han ),김호각 ( Ho Gak Kim ),정진태 ( Jin Tae Jung ),권중구 ( 대한소화기학회 2014 대한소화기학회지 Vol.63 No.6
Background/Aims: Obesity increases the risk of colorectal cancer and adenomatous polyp, and one of the underlying mechanisms of this increase is considered to be due to the growth promoting effects of adipokines, such as leptin. In order to investigatethis finding, leptin expression in the colonic tissue and blood leptin concentration of the colonic adenoma patients were compared to those of the control group. Methods: Colonic adenoma tissues were obtained by polypectomy (n=60). In these patients, normal colonic mucosa at remote areas from the polyp was also obtained and blood samples were collected as well. Age and sex matched control subjects were selected among those who showed normal colonic mucosa in health screening colonoscopy (n=60).Results: There was no significant difference in serum leptin concentration between the colonic adenoma patients and control subjects. Leptin expression was noted in 43.3% of the colonic adenomas, but only in 6.7% of normal colonic mucosa fromthe control subjects (p<0.01). There were ten cases of concurrent adenocarcinoma in situ in adenoma patients, eight cases of which expressed leptin (p=0.01). In adenoma group, leptin expression rate was significantly high in larger adenomas and in obese patients (p<0.05). However, there was no statistically significant relationship between leptin expression in colonicmucosa and serum leptin level. Conclusions: Leptin expression was more frequently observed in colonic adenomas, especially in larger adenomas associated with adenocarcinoma in situ, but blood leptin level was not related to tissue leptin expression. Leptin expression was more frequently observed in obese patients from the adenoma group. Therefore, leptin may play an important role in colonic tumori-genesis and progression, especially in obese patient. (Korean J Gastroenterol 2014;63:354-360)