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광음향 효과를 이용한 레이저 유리의 고아흡수계수의 분석
박용환 永同大學校 1997 硏究論叢 Vol.3 No.1
평균 출력 20 W의 CW-Nd:YAG 레이저의 10.6㎛의 빛을 이용하여 레이저유리 LG-750의 광음향 신호를 측정한 후 Bonnet-Forman의 이론을 이용하여 분석하였다. 광흡수계수(β_eff)는 덩어리 흡수계수(β_B)와 표면 흡수계수(β_s)로 구분할 수 있으며 β_eff = β_B + 2β_s/l_s의 형태로 주어진다. 두 흡수계수 사이의 비 값( r = β_s /β_B)과 광음향 신호의 주파수 의존도의 관계로부터 레이저 유리의 흡수계수를 분석 하였다. 레이저 유리의 두께가 두꺼울수록 표면 흡수계수보다 덩어리 흡수계수에 의한 성분이 증가하는 것을 확인하였다. 레이저 유리 LG-750의 덩어리 흡수계수는 0.00130 cm^-1이며, 레이저 유리의 두께가 2, 3, 8, 10 mm일 때 표면 홉수계수는 각각 6.50×10^5, 4.30×10^-5, 2.45×10^-5 및 1.53×10^-5인 것으로 계산되었다 Photoacoustic(PA) signals were obtained as a function of chopping frequency on laser glass LG-750 using a 10.6㎛ CW-Nd:YAG laser with 20 W incident power. Theoretical calculations were made using Bennet-Forman theory. Optical absorption coefficient can be separated into the bulk- and suface optical absorption coefficient by PA method and defined as β_eff = β_B + 2β_s/l_s. The absorption coefficients of the laser glass were analysed with relationship the bulk to surface absorption ratio and the frequency dependence of the PA signal. The bulk absorption is more dominant in the thick sample than the suface absorption. For LG-750, β_B = 0.00130 cm^-1. And β_s = 6.50×10^-5, 4.30×10^-5, 2.45×10^-5 and 1.53×10^-5 for 2, 3, 8 and 10 mm thickness.
김용채,이창희,이진호,서일환,추금홍,이정수,성백석,김문집 순천향대학교 기초과학연구소 1998 순천향자연과학연구 논문집 Vol.4 No.2
The anisotropic thermal factor of an atom located at a general position has six parameters as follows: ?? If the atom is placed at a special position, the anisotropic thermal factor must have the same symmetry as the special position has. The symmetries at the special positions reduce the 6 anisotropic thermal parameters to 4 or 3 or 2 or 1 and there are 18 different kinds of anisotropic thermal factors altogether for special positions in 230 space groups.
각막형태검사법을 이용한 각막양상과 눈의 굴절력과의 관계
최시환,민병무,김용백,김창식,안승일 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1
We evaluated the topography of 200 normal cornea of Korean. The mean age was 37 years and mean refractive astigmatism was 0.82±0.69D. The corneal patterns were classified by Dr. Bogan such as round, oval, symmetric bow tie, asymmetric bow tie, and irregular pattern. Its incidence was 14.0%, 11.0%, 16.0%, 30.0% and 29.0%, respectively. There was no statistically significant difference in the distribution of topographic pattern in male and female and among age groups. The symmetric bow tie type had the greatest spherical equivalent and astigmatism and there was no statistically significant difference in those two values between round and oval group. Two bow-tie groups were not also statistically significantly different from each other in spherical equivalent and astigmatism. However, two bow tie groups were significantly different from round and oval group. So, it was possible to divide corneal topographic pattern into three groups such as round and oval, two bow tie, and irregualr group. We could understand normal corneal status related to corneal pattern and refractive power through this qualitative system for classifying corneal topography.
정문용(Yong, Yeong-Mun),이무식(Lee, Moo-Sik),나백주(Na, Bak-Ju),김철웅(Kim, Chul-Woung),김광환(Kim, Kwang-Hwan),유인숙(Yoo, In-Sook) 한국산학기술학회 2009 한국산학기술학회 학술대회 Vol.- No.-
요 약 신종 및 재출현 전염병이 지속적으로 유행하고 해외 전염병의 국내유입가능성이 증대됨에 따라 국립검역소의 검역관리 사업의 효율성 평가는 매우 중요하다. 연구는 평가 구성요소 사이의 상대적 중요도, 즉 가중치(weight) 부여에 있어서 과학적 타당성을 인정받고 있는계층분석절차(Analytical Hierarchy Process; AHP) 기법에 의한 이원비교방법을 사용하여 설정하였다. AHP기법은 복잡한 다기준 의사결정문제(multi-criteria decision making problem)를 계층화하여 단순화․체계화시킴으로써 그 영향도를 계량화하는데 탁월한 기법이라는 평가를 받고 있다. 실제 측정에 있어서는 본 모형을 이용하여 얻어졌다. 대영역(기관평가영역, 서비스 및 프로그램평가 영역), 중영역(투입, 과정, 결과, 검역업무, 검사업무, 위생관리업무, 병원체조사감시업무, 전염병예방홍보․교육업무)으로 구분하여 최종적으로 평가지표로 선정된 지표는 실제 국립검역소 사업에 적용하였으며, 이에 대한 최소한의 평가지표를 최종 선정하여 향후 국립검역소사업 평가체계를 보다 체계화 하였다.
Hydraulics of KSTAR Central Solenoid Model Coil 2nd Campaign
Soo Hwan Park,Han, W.S.,Moon, K.M.,Park, W.W.,Kim, J.S.,Yonekawa, H.,Yong Chu,Hyun Jung Lee,Cho, K.W.,Park, K.R.,Kim, W.C.,Yaung-Soo Kim,Oh, Y.K.,Bak, J.S. IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet consists of a CICC (Cable-In-Conduit Conductor) and is cooled down less than 5 K using supercritical helium. The length of CICC is 610 m for TF coil and maximum about 2,500 m for PF coil respectively, especially the cooling channel is about maximum 300 m in PF coil because of continuous winding scheme. There are many cooling channels in KSTAR coils especially 84 channels in TF magnet system and 100 channels in PF magnet system. Flow imbalance affects cool down of magnet and leads to a difficulty of flow control. The pressure drop between CICC terminals has a close relationship with CICC hydraulic characteristic, helium refrigerator's performance and efficiency. The friction factor which is a representative parameter can be obtained under cryogenic operation condition. We attempt to find out the friction factor of KSTAR CS and PF CICC according to the test result of KSTAR CSMC (Central Solenoid Model Coil) 2nd campaign and compare the results with previous tests. The hydraulic characteristics of KSTAR superconducting magnet system like mass flow distribution, friction factor in conductor, pressure drop and etc during CSMC test and initial commissioning of KSTAR are presented. We can confirm the KSTAR CICC's unique hydraulic behavior in states of cool down and current charging period. Also, we expect that measured data will help to operate KSTAR and be a reference for thermo-hydraulic simulation.</P>