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- 저자 : 주정식(Jung Sik Joo) (검색결과 5 건)
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근적외선을 여기광으로 하는 Yb, Tm이 도핑된 LaGaO3 형광체의 업컨버젼 형광 특성
주정식(Jung Sik Joo),양현경(Hyun Kyoung Yang),제재용(Jae Yong Je) 한국방사선학회 2015 한국방사선학회 학술대회 논문집 Vol.2015 No.추계
LaGaO3:Tm3+, Yb3+분말은 Yb3+의 함량(0∼0.15 mol)을 변화시겨 고상반응법으로 합성하였다. X-선 회절(XRD), 에너지분석법(EDS)을 통해 결정구조 및 화학적 특성을 각각 분석하였다. 형광특성을 분석하였으며, 형광스펙트럼을 통하여 Tm3+의 f12 전자 궤도에서 발생하는 1G4-3H6 전이와 약한 1G4-3F4 전이 그리고 강한 3H4-3H6 전이와 함께 Yb3+에 의한 2F5/2-2F7/2 전이가 일어남을 확인하였다. LaGaO3:Tm3+,Yb3+ 분말의 업컨버젼 형광특성은 975 nm의 여기 파장을 가지는 레이저 다이오드를 사용하여 측정하였다. 합성한 시료에서 업컨버젼 형광 스펙트럼이 발생함을 확인하고 스펙트럼을 분석하였다. 또한, 본 시편에 대한 업컨버젼 형광의 원리를 제안하였다. We synthesized A LaGaO3:Tm3+, Yb3+ powder with different Yb3+ contents (0∼0.15 mol) using of a conventional solid-state reaction. The structure, morphology and chemical analysis of the as-prepared phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques, respectively. The study was the photoluminescence properties of the as-prepared powder samples. The spectrum consisted of 1G4-3H6, weak 1G4-3F4, and intense 3H4-3H6 transition bands within the f12 configuration of Tm3+, together with the 2F5/2-2F7/2 transition of Yb3+. Up-converted emission of LaGaO3:Tm3+, Yb3+ powders was observed under laser diode excitation of 975 nm. We observed obvious differences in up-converted emission spectra among the as-obtained products, and possible reasons were discussed. we also proposed The corresponding up-conversion mechanism.
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한상을,양재근,주정식,Han, Sang-Eul,Yang, Jae-Guen,Joo, Jung-Sik 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.3
본 연구에서는 구조 요소의 응력해석을 위한 무요소 RPIM(Meshfree Radial Point Interpolation Methods)법을 제시한다. 이를 위하여 먼저 무요소법의 형상함수와 무요소 RPIM법의 정식화 과정 및 프로그래밍을 간략히 한다. 절점보간법은 방사기저함수와 다항기저함수를 포함하고 있고 이 중 다항기저함수는 특이성문제를 극복할 수 있다. 게다가 무요소 RPIM법의 보간함수는 영향영역의 절점을 통과하고 형상함수는 크로네커 델타 성질을 갖고 있으므로 최소자승법에 기반을 둔 무요소법보다 쉽게 필수경계조건을 만족시킨다. 본 연구의 정확성을 확인하기 위하여, 캔틸레버형 평판, 유공평판, 속이 빈 원통 문제의 수치예제를 수행하고 이론 해와 유한요소법 결과를 비교, 분석한다. A Meshfree is a method used to establish algebraic equations of system for the whole problem domain without the use of a predefined mesh for the domain discretization. A point interpolation method is based on combining radial and polynomial basis functions. Involvement of radial basis functions overcomes possible singularity Furthermore, the interpolation function passes through all scattered points in an influence domain and thus shape functions are of delta function property. This makes the implementation of essential boundary conditions much easier than the meshfree methods based on the moving least-squares approximation. This study aims to investigate a stress analysis of structural element between a meshfree method and the finite element method. Examples on cantilever type plate, hollow cylinder and stress concentration problems show that the accuracy and convergence rate of the meshfree methods are high.
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무요소의 적응적 세분화 방법을 이용한 국부화문제의 해석
한상을(Han Sang-Eul),이상주(Lee Sang-Joo),주정식(Joo Jung-Sik) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.3
The Meshfree method is a method used to establish a system of algebraic equations for the whole problem domain without using predefined mesh for the domain discretization. Point interpolation method is based on combination of radial and polynomial basis functions. Introducing of radial basis functions overcomes possible singularity problem. Furthermore, the interpolation function is applicable for all points scattered over in influence domain and thus shape functions are of delta function property, which makes the implementation of essential boundary conditions much easier than the meshfree methods based on the moving least-squares approximation. In this study, an adaptive node generation procedure in the radial point interpolation method is proposed. Since we set the initial configuration of nodes by subdivision of background cell, abrupt changes of inter-nodal distance between higher and lower error regions are unavoidable. This unpreferable nodal spacing induces additional errors. To obtain the smoothy nodal configuration, it's regenerated by local Delaunay triangulation algorithm. This technique was originally developed to generate a set of well-shaped triangles and tetrahedra. In order to evaluate the error estimation technique, cantilever type plate was investigated. To demonstrate the performance of proposed scheme, the results of making optimal nodal configuration with adaptive refinement method are investigated for stress concentration problems.
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한상을(Han Sang-Eul),양재근(Yang Jae-Guen),주정식(Joo Jung-Sik) 대한건축학회 2007 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.27 No.1
A Meshfree is a method used to establish algebraic equations of system for the whole problem domain without the use of a predefined mesh for the domain discretization. A point interpolation method is based on combining radial and polynomial basis functions. Radial basis function(RBF) augmented with polynomials is used to construct the shape functions. These shape functions possess delta function property that makes the numerical procedure very efficient and many techniques used in the finite element method can be adopted easily. Furthermore, the interpolation function passes through all scattered points in an influence domain and thus shape functions are of delta function property. This makes the implementation of essential boundary conditions much easier than the meshfree methods based on the moving least-squares approximation. A plate with a hole subjected to a tensile load and a V-notched tension specimen are analyzed and their stress distributions match well with those obtained by finite element commercial software ANSYS or the available literature.
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朱井植 건국대학교 1982 論文集 Vol.15 No.1
In this note, our object is study of the subring C*(X) of all real valued bounded continous functions on Tychonoff-space X and is to study relations between topological properties of a space X and algebraic properties of C*(X) Furthermore, our aim is to characterize paracompact M-spaces in terms of C*(X).
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