Zn[1-x]Mn[x]S 단결정 박막의 결정구조 및 광발광 특성

최용대 한국물리학회 2004 New Physics: Sae Mulli Vol.49 No.3

Zn$_{1-x}$Mn$_x$S epilayers were grown on GaAs(100) using hot-wall epitaxy. The surface state of the grown epilayers was observed by using a Nomarski microscope and an atomic force microscope. X-ray diffraction revealed that the Zn$_{1-x}$Mn$_x$S films had a zinc-blende structure, and double-crystal rocking-curve spectra showed that the crystal quality got worse with increasing Mn composition. The Mn composition was determined with an electron probe X-ray microanalyzer and a relation between the Mn composition and the lattice constant was found. The Mn composition dependence of the photoluminescence was measured at 10 K without a external magnetic field. 본 연구에서는 hot-wall epitaxy 방법으로 GaAs(100) 기판 위에 Zn$_{1-x}$Mn$_x$S 단결정 박막을 성장하였다. 성장된 시료는 Nomarski 현미경과 AFM(atomic force microscope)을 이용하여 박막의 표면을 분석하였다. XRD(X-ray diffraction)로부터 Mn 조성비와 무관하게 모든 Zn$_{1-x}$Mn$_x$S 단결정 박막은 화학양론적인 zincblende 구조로 성장하였음을 확인하였고, DCRC(double-crystal rocking curve)로부터 Mn 조성비가 증가하면 박막의 결정성이 나빠지는 것을 알 수 있었다. EPMA(electron probe X-ray micro analyzer)를 이용하여 구한 화학적인 조성비와 DCRC로부터 구한 격자상수와의 관계로부터 zincblende 구조인 MnS의 격자상수를 구하였다. 그리고 외부 자기장이 없을 때 Mn 조성비에 따른 Zn$_{1-x}$Mn$_x$S 단결정 박막의 10 K 광발광 스펙트럼을 측정하다.

Vectorial Polarization Modes Platform Realized with Jones Vectors in Mathematica

최용대,윤희중 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.5

The fundamental concept in physics of polarization propagation of electromagnetic waves is newly understood to be a cardinal keyword in quantum cryptography transport technology and the Standard Model. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has received attention recently from scientists in the age of information and communication. This study presents a new dynamic polarization platform that presents the polarization modes of a transverse electromagnetic wave by using Jones vectors calculations in the symbolic program Mathematica to convert the state of polarization through the arrangement of the optical elements. The platform simulates a propagation process that satisfies Maxwell’s two vector equations precisely with the vectorial nature of the electromagnetic wave.

누두흉의 수술 교정 방법에 관한 비교연구

최용대,김민호,김공수,Choe, Yong-Dae,Kim, Min-Ho,Kim, Gong-Su 대한흉부심장혈관외과학회 1992 Journal of Chest Surgery Vol.25 No.3

From Jan. 1981 to Dec. 1989 eleven cases of Funnel Chest, ten were males and one was female, were underwent an operation at the Department of Thoracic and Cardiovascular Surgery. Cheonbuk National University Hospital. The age of patients ranged from 3 to 29 years old. They all had symptoms of feeling inferiority about chest deformity. The degree of concavity on the funnel chest varied in extent, and the severity which was measured by water volume filled into it varied from 20 ml to 140 ml. Nine patients were corrected by Ravitch method and two patients were corrected by the Modified sternal turnover method. The Ravitch method was more effective in asymmetrical, severe depression deformity and in children. On the other hand the Modified sternal turnover method with preservation of vascular supply of repair was more simple and more effective in case of relatively less severe, wide symmetrical depression deformity of the chest and in case of associated with congenital or acquired heart disease and disease of the ascending aorta. This method has the advantage of maintaining chest wall stability in postoperative period.

GaAs (100) 기판 위에 성장된 묽은 자성 반도체 Zn₁-xMnxTe에 피층의 특성

최용대,유영문,박재규,현명학,오병성,이기선,윤만영,유평렬 한국진공학회 2001 한국진공학회 학술발표회초록집 Vol.- No.-

Vector Field Platform for Visualizing Electric and Magnetic Fields in Matter using Mathematica

최용대,윤희중 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.6

Vector fields can be used to represent physical quantities in various area of physics, including gravitational field and electromagnetic field with vector differential operators. As this involves abstract, three-dimensional fields that are sometimes very difficult to visualize, electromagnetism in matter can be rather conceptual. A visual representation of abstract vector fields in matter is invaluable to students or researchers working in this field and helps teachers to teach electromagnetism to physics or engineering students. We visualized the most fundamental concepts of electromagnetic vector fields: $\vec{E}= -\vec{\nabla} \varphi,\ \vec{D}= \epsilon \vec{E},\ \vec{B}= \vec{\nabla}\times \vec{A},\ \vec{H}=-\vec{\nabla} \phi^*,\ \text{and}\ \vec{B}= \mu \vec{H}$, all of which were calculated using the vector differential operators in $Mathematica$. This visualization based on vector calculations can be used as a starting platform for exploring electromagnetic vector fields.

고용연한제가 아닌 고용안정 쟁취를 위해

최용대 한국비정규노동센터 2005 비정규 노동 Vol.38 No.-

ZnS_(1-x)Te_x 단결정 박막의 격자진동

최용대,남성운,유영문 목원대학교 자연과학연구소 2000 自然科學 硏究論文集 Vol.9 No.1

Hot-wall epitaxy에 의하여 GaAs (100) 기판 위에 성장된 ZnS_1-xTe_x(0<x<1) 단결정 박막의 특성이 Raman 산란을 이용하여 조사되었다. Raman 산란으로부터 측정된 장파장의 ZnTe-like의 longitudinal 광학 포논의 주파수는 성분비 x와 함께 선형으로 변하였다. ZnS_1-xTe_x 단결정 박막의 x의 함수로서 zone-center 광학 포논의 주파수는 two-mode이었고, 이 결과는 MERI 모델의 이론치와 잘 일치하였다. ZnS_1-xTe_x(0<x<1) alloys grown on (100) GaAs substrates by hot-wall epitaxy are investigated using Raman scattering. The frequencies of long wavelength ZnTe-like and ZnTe-like longitudinal optical phonons determined from Raman scattering show linear variation with the composition x. The frequency of the zone-center optical phonons as a function of x of the ZnS_1-xTe_x mixed crystal shows a typical two-mode behavior. which is in good agreement with the theoretical results from a modified random-element isodisplacement model.

Platform for Manipulating Polarization Modes Realized with Jones Vectors in MATHEMATICA

최용대,김보경,윤희중 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.2

The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD) to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

CuS/CdS 박막제작과 태양전지로의 응용

최용대 牧園大學校 1986 論文集 - 牧園大學校 Vol.11 No.-

CdS polycrystalline thin films were deposited on the ITO substrate by the chemical bath deposition method. Cu₂(CuS)S/CdS heterojunction thin film solar cell formed on CdS thin films using a chemical reaction method. The maximum short-circuit current, open-circuit voltage, fill factor, and energy conversion efficiency of Cu₂(CuS)S/CdS heterojunction thin film solar cells obtained at 80 mW/cm² were found to be 6.2mA/cm², 0.3V, 0.44 and 1.03%, respectively.

ZnSe:Mn, Cl 형광체의 Photoluminescence에 관한 연구

최용대,양동익,신영진 全北大學校 1984 論文集 Vol.26 No.-

A study has been made of the photoluminescence of Zinc selenide phosphors. Activator and coactivator used are manganese and chiorine. Two kinds of phosphor samplem, that is, SA ZnSe and ZnSe:Mn, CI phosphors are prepared by firing Zinc selenidc with appropriate impurity at 900℃ for an hour in nitrogen gas. The crystal structure of these phosphors shows the cubic phase.