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GaAs/AlGaAs 양자우물 구조에서의 공명터널링시간 계산
최정우 慶熙大學校 材料科學技術硏究所 1993 材料科學技術硏究論集 Vol.6 No.-
Resonant states in a cascade process are found from the pole of the scattering matrix in the complex energy plane. We found that use of the WKB method at resonance is unfounded.
신우석,최규하,정만규 건국대학교 산업기술연구원 1994 건국기술연구논문지 Vol.19 No.-
This paper describes voltage-controlled delta-modulation scheme for active power filters, which is to control the harmonic-compensating current indirectly by adjusting the capacitor voltage to be sinusoidal. The overall control system has two feedback loops : one is the outer proportional feedback for loop regulating the de current of the active filter and the other is the inner feedback loop for maintaining the ac current waveform to be sinusoidal, and to have zero power factor angle(i. e. unity power factor). The characteristics of the proposed scheme are investigated by digital simulation using ACSL.
AI 조성비 변화에 따른 GaAs/AIGaAs 다중양자우물구조 특성변화 연구
유연희,최정우,임재영,노삼규 慶熙大學校 材料科學技術硏究所 1998 材料科學技術硏究論集 Vol.11 No.-
We manufactured and characterized different sets of GaAs/AlGaAs multiple quantum well structures for the long wavelength infrared photodetection. The samples were grown by MBE. We changed the aluminum composition of barrier region from 0.24 to 0.30 in 0.02 steps, and performed double crystals X-ray diffraction(DCXRD) and the photoluminescence measurements. DCXRD measurements correctly gave the expected aluminum compositions. Photoluminescence measurements revealed that the ground state energy of the well increases with composition as desired, but the change was not very significant.
GaAs/AIGaAs 양자우물구조 검출기의 구속-연속상태 전이연구
황형준,최정우,최우석 慶熙大學校 材料科學技術硏究所 1997 材料科學技術硏究論集 Vol.10 No.-
We study the methods to calculate the bound-to-continuum transition amplitudes in a biased GaAs/AlGaAs quantum well detector structure. First we apply the complex energy method to evaluate the energy levels of meta-stable states. We also present how the coefficients of the travelling waves change with the complex value of energy. Transition amplitudes to each continuous scattering states are also calculated. The transition peaks evaluated agree well with the energy levels of the meta-stable states found using the complex energy method.
GPIB 연결장치로 자동화한 장파장 적외선 검출기 특성 측정장치
이상준,최정우 慶熙大學校 材料科學技術硏究所 1995 材料科學技術硏究論集 Vol.8 No.-
We have constructed a special purpose computer controlled system for the photo response measurement in the long wavelength infrared range, using a GPIB interface. It uses a Si-nite black body source and a monochromator with gold coated mirrors. It shows strong photon flux density in the range of interest. However the noise figures measured came out much greater than the ones quoted by the company, suggesting the necessity for the development of noise suppressing ways.
이찬우,최정우 慶熙大學校 材料科學技術硏究所 1994 材料科學技術硏究論集 Vol.7 No.-
As a preliminary step to develop a silicon based homojunction infrared detector operating in the long-wavelength infrared range and beyond, we investigate the thermionic emission characteristics of a silicon p-i-n diode Toshiba TPS703 at the extremely low temperatures such as below 30K. We vary the forward bias to the test structure to measure the Ⅰ-Ⅴ characteristics at various temperatures, and compare the results with the theoretical model by yang et al. [Appl. Phys. Lett. 45, 752 (1984)]. A reasonable correspondence has been achieved.
황형준,권태진,최정우 慶熙大學校 材料科學技術硏究所 1999 材料科學技術硏究論集 Vol.12 No.-
We estimate the ground state energy and wavefunction in the biased quantum well structure by using the periodic boundary condition. In this calculation, we assumed that the probability of finding the particle has maximum value at the ground state energy and the amplitude of the wavefunction should not depend on a period. The obtained energy value was in good agreement with the result predicted by the complex energy method.
김윤철,이정우,김보영,강정아,임대승,이민수,김정희,성보영,최성준,성인환,전은석 충남대학교 의과대학 지역사회의학연구소 2000 충남의대잡지 Vol.27 No.1
Coronary stent implacement is known as an effective treatment in the intimal dissection after percutaneous transluminal coronary angioplasty and the prevention of restenosis. However, In-stent restenosis still remains a major concern in clinical stenting. The stents were placed in 103 patients from July 1996 to March 1999 and performed follow-up coronary angiograms in 59(57.3%) patients. To identify the clinical, angiographic and procedurerelated variables 'which predict late restenosis within the stented artery, 59 patients(58.3±9.9, M:F= 41:18) were studied. The clinical characteristics of the patients were stable angina in 23(39.0%), unstable angina in 14(23.7%), acute myocardial infarction in 21(35.6%) and old myocardial infarction in 1(1.7%). Coronary stenting was performed in 1 patient(1.7%) for primary lesion, 50 patients(84.7%) for suboptimal results after PTCA, 6 patients(10.2%) for bail-out procedure, and 2 patients(3.4%) for restenotic lesions. All patients were treated with aspirin and ticlopidinc. The follow-up angiograms were obtained at 7±4 months. The overall in-stent restenosis rate was 27.1%. The coronary angiographic findings were 32 single vessel(54.2%), 19 two vessel(32.2%) and 8 three vessel disease(13.6%). The angiographic morphological characteristics were type A in 33(55.9%), type B in 14(23.7%), type C in 12(20. 3%) cases. Variables of 16 patients with restenosis were compared with those of 43 patients without restenosis. Previously known predictors for in-stent restenosis were multiple stenting, stenting for restenotic lesions, residual stenosis after stenting, stenting for total occlusion lesions, reference diameter, balloon to vessel ratio, acute gain and minimal luminal diameter after procedure, design and characteristics of stents, ostial lesion of aorta, high pressure method for stenting, lesion length, diabetes mellitus, size of artheroma, saphenous vein grafts, ulcerlating lesions and calcified lesions. In this study, Reference diameter before stenting(2.43±0.54mm vs. 2.88±0.65mm, p=0.016) and balloon-to-artery ratio(1.28±0.26 vs. 1.11±0.18, p=0.006) were predictors for in-stent restenosis. 1) The overall in-stent restenosis rate was 27.1%. 2) In the analysis of predictors for in-stent restenosis, there was no significant differences in clinical, angiographic factors between group with restenosis and without restenosis. But, Only reference diameter before stenting and balloon-toartery ratio were predictors of late in-stent restenosis. In conclusion, stenting is effective revascularisation method for selected patients with ischemic heart disease, and to minimize in-stent restenosis rate, stent implanting is achieved in a large vessel on the basis of an artery-to-stnet ration of 1:1, if possible.
The Relations Between The Tensor Space And The Symmetric Permutaion Group
Choe, Jeong Woo 울산대학교 1984 연구논문집 Vol.15 No.1
벡터 공간으로부터 유도되는 텐서 공간과 치환군의 공간과의 관계를 조사하였다. 새로운 연산자 # 와 ??을 도입하였고 이를 이용하여 두 공간의 긴밀한 연계성을 밝혔다. The relation between the tensor space which is induced on a vector space and the symmetric permutation group space is regorously investigated. The operations # and ?? which relate the two spaces are introduced. By these analogy obtain the close analogy between the two spaces.