Mo¨ssbauer 분광법을 이용한 10MnO_2-10Fe_2O_3-30Na_2O-50SiO_2 유리내의 Fe^3+ 이온에 관한 연구

洪致裕,朴冠鎬,白承道,洪性樂 동국대학교 1986 論文集 Vol.25 No.-

We have studied the Mo¨ssbauer parameters for Fe^(3+) ion in the quenched glass and heat treated glass and heat treated glasses. The Mo¨ssbauer spectra of the quenched glass were investigated at various temperatures from 60K to 300K. Using the center shift and kinetic temperature, the Debye and einstein temperatures were calculated. The quenched glass was heat-treated at various temperatures from 530℃ to 710℃ for five hours. Both the isomer shit and quadrupole splitting parameters decreased near 590℃. And regardless of heat treatment, the Fe^(3+) ion was predominantly octahedrally coordinated.

10MgO-10Fe_2O_3-30Na_2O-5OSiO_2 유리의 Mo¨ssbauer 효과 연구

홍치유,박관호,백승도,문찬호,조수열 동국대학교 1987 論文集 Vol.26 No.-

The Mo¨ssbauer effect studies of the quenched glass and heat-treated glasses were performed. The Debye and Einstien temperatures of the quenched glass, determined using the center shift and kinetic temperature, are 540K and 430K respectively. The X-ray diffraction pattern showed that the heat-treated glasses were crystallized. Form the isomer shift of the heat-treated glasses, it was concluded that the Fe^(3+) ion is predominantly octahedrally coordinated.

(±)-6a, 7-Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo [b,d] pyran-9(8H)-one의 염소화 반응에 관한 연구

홍기운,육찬남,백승화 圓光大學校 1991 論文集 Vol.25 No.2

(±)-6a, Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo[b,d] pyran-9[8H]-one의 염소화 반응은 metal halide와 함께 18-crown-6존재하에m-chloroperbenzoic acid에 의해 산화반응이 일어났다. 이 반응계에서는 염소화 반응이 방향족 고리에만 선택적으로 일어났다. (±)-6a, 7-Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo [b, d]pyran-9(8H)-one has been chlorinated in the aromatic ring with metal halide in the presence of 18-crown-6 on oxidation with m-chloroperbenzoic acid. This reagent system effects the regiospecific chlorination of activated aromatic ring over olefinic double bond.

Ni1-xCdxFeAlO₄계의 Mossbauer 스펙트럼 연구

홍성락,고정대,백승도 濟州大學校 基礎科學硏究所 1998 基礎科學硏究 Vol.11 No.2

Ni1-xCdxFeAlO₄계의 Mossbauer스펙트럼은 x가 0.2이하인 경우에는 초상자성 이완현상을, x가 0.3~0.5인 경우에는 준강자성에 의한 sextet를 x가 0.7, 0.8인 경우에는 강자성 이완현상, x가 0.8이상인 경우에는 상자성에 의한 doublet가 나타난다. x가 0.2이하인 시료에서 치환된 Cd²이온은 주로 A-site의 Al³이온을 B-site로 이동시키고, 계속적인 Cd²이온의 증가에 따라 A-site의 Fe³+ 이온도 B-site로 이동하게 된다. Ni1-xCdxFeAlO₄계의 초상자성 이완 현상은 A-site의 Al³이온에 의한 것으로 강자성 이완현상은 치환된 Cd²+이온에 의한 것으로 설명할 수 있고, Yafet-Kittel자기구조에 따라 Ni1-xCdxFeAlO₄계의 자기적 성질을 해석할 수 있다. The Mossbauer spectra of the Ni1-xCdxFeAlO₄system were investigated with the Cd content X at room temperature. The spectra of the samples exhibit various patterns as follows 1) superparmagnetic relaxation for 0≤x≤0.2, 2)ferrimagnetic sextet for 0.3≤x≤0.5, 3) ferromagnetic relaxation for x=0.6, 0.7, 4)paramagnetic doublet for 0.8≤x≤1, with the Cd content x. In the samples with X values from O to 0.2, the substituted Cd²+ ions transfer the Al³+ ions from A-site to B-site mainly. The superparamagnetic relaxation effect and the ferromagnetic relaxation effect are derived from the Al³,Cd²respectively. The magnetic structrue of the Ni1-xCdxFeAlO₄system was explained by the Yafet-Kittel model.

Hot Wall Epitaxy(HWE)에 의한 CdGa₂Se₄/GaAs epilayer 성장과 광전기적 특성

백승남,홍광준 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.1

The stochiometric mix of evaporating materials for the CdGa₂Se₄single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, CdGa₂Se₄mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 630℃ and 420℃, respectively. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of CdGa₂Se₄single crystal thin films measured from Hall effect by van der Pauw method are 8.27×10^(17) ㎤, 345 ㎠/V ·s at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the CuInSe₂ single crystal thin film. We have found that the values of spin orbit splitting △So and the crystal field splitting △Cr were 106.5 meV and 418.9 meV at 10 K, respectively. From the photoluminescence measurement on CdGa₂Se₄single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exicition (D^(0) ,X) having very stron peak intensity. Then, the full-width-at-half-maximum(FWHM) and binding energy of neutral donor bound excition were 8 meV and 13.7 meV, respectivity. By Haynes rule, an activation energy of impurity was 137 meV.

도재 라미네이트와 복합레진 수복 시 치간이개 양에 따른 접착계면의 응력분포에 관한 3차원 유한요소법적 연구

홍준배,탁승민,백승호,조병훈 大韓齒科保存學會 2010 Restorative Dentistry & Endodontics Vol.35 No.1

본 연구에서는, 삼차원 유한요소분석법을 이용하여 복합레진 및 도재 라미네이트로 전치부 치간이개를 폐쇄할 때, 치간이개의 간격과 수복방법이 수복물의 접착계면에서의 응력분포에 미치는 영향을 비교하였다. 복합레진 혹은 도재 라미네이트로 수복된 모습의 유한요소모델을 형성하여 접착계면에서의 von Mises stress 분포 양태를 분석하였다. 수복형태는 크게 네 가지 범주를 고려하였다. Type I, 복합레진으로 인접면을 최소한으로 수복하는 경우; Type II, 치아 삭제 없이 복합레진으로 순면의 절반까지 수복하는 경우; Type III, 치아삭제 후복합레진으로 순면의 2/3까지 수복하는 경우; Type IV, 도재 라미네이트로 수복하는 경우 이 실험의 한계 내에서 다음과 같은 결론을 내릴 수 있었다. 모든 수복형태에 대해 치간이개 간격이 넓어질수록 접착계면에서 발생하는 최대응력 값은 증가하였으며, 도재 라미네이트로 치간이개 부위를 수복한 경우(Type IV)가 복합레진으로 수복한 경우(Type I, II, III)에 비해 높은 최대응력값을 나타내었다. 그러나 치간이개 간격이 넓어질수록 도재 라미네이트와 복합레진에서 발생하는 최대응력값의 차리는 감소하였으며, 치간이개 간격의 증가에 따른 최대응력값의 증가율은 도재 라미네이트가 복합레진으로 수복하는 경우보다 낮았다. This study evaluated the influence of the type of restoration and the amount of interdental spacing on the stress distribution in maxillary central incisors restored by means of porcelain laminate veneers and direct composite resin restorations. Three-dimensional finite element models were fabricated to represent different types of restorations. Four clinical situations were considered. Type I, closing diastema using composite resin. Labial border of composite resin was extended just enough to cover the interdental space; Type II, closing diastema using composite resin without reduction of labial surface. Labial border of composite resin was extended distally to cover the half of the total labial surface; Type III, closing diastema using composite resin with reduction of labial surface. Labial border of the preparation and restored composite resin was extended distally two-thirds of the total labial surface; Type IV, closing diastema using porcelain laminate veneer with a feathered-edge preparation technique. Four different interdental spaces (1.0, 2.0. 3.0, 4.0 mm) were applied for each type of restorations. For all types of restoration, adding the width of free extension of the porcelain laminate veneer and composite resin increased the stress occurred at the bonding layer. The maximum stress values observed at the bonding layer of Type IV were higher than that of Type I, Ⅱ and Ⅲ. However, the increasing rate of maximum stress value of Type IV was lower than that of Type I, Ⅱ and Ⅲ.

(±)-6a, 7-Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo[b, d] Pyran-9(8H)-one의 염소화 반응에 관한 연구

백승화,홍기운,육찬남 원광대학교기초자연과학연구소 1992 基礎科學硏究誌 Vol.11 No.3

(±)-6a, 7-Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo[b, d] pyran-9[8H]-one 의 염소화 반응은 metal halide와 함께 18-crown-6존재하에 m-chloroperbenzoic acid에 의해 산화반응이 일어났다. 이 반응계에서는 염소화 반응이 방향족 고리에만 선택적으로 일어났다. (±)-6a, 7-Dihydro-1-hydroxy-6, 6-dimethyl-3-pentyl-6H-dibenzo[b, d] pyran-9[8H]-one has been chlorinated in the aromatic ring with metal halide in the presence of 18-crown-6 on oxidation with m-chloroperbenzoic acid. This reagent system effects the regiospecific chlorination of activated aromatic ring over olefinic double bond.

실제좌표 공간에서 선형 진동시스템의 해석기법

백승호,황재혁,박명호,이재홍 한국 항공대학교 항공산업기술연구소 1996 航空宇宙産業技術硏究所 硏究誌 Vol.6 No.-

The coefficients of a linear nonconservative system are arbitrary matrices lacking the usual properties of symmetry and definiteness. A method is developed herein for the efficient analysis of linear nonconservative systems. This constructive method utilizes equivalence transformations, and does not require conversion of the equations of motion to first-order forms.

NiCdFe₂O₄의 구조와 자기적 성질

홍치유,조수열,백승도 동국대학교 자연과학연구소 1991 자연과학연구 논문집 Vol.11 No.-

X-ray 회절선을 조사한 결과 Ni?Cd?Fe?O?의 조성을 갖는 ltfy는 x값의 증가에 따라 inverse spinel 구조에서 normal spinel 구조로 변하며, 격자상수는 선형적으로 증가하였다. 또한 Mossbauer spectrum을 상온(300K)에서 측정하여 분석한 결과, 시료의 wrl적 성질은 x값의 증가에 따라 준강자성에서 상자성으로 변화되었으며, 시료는 Yafet-Kittel의 자기구조를 이루는 것을 알 수 있었다. According to the X-ray diffractometry, the structure of Ni?Cd?Fe?O? changes from inverse spinel to normal spinel and lattice constant varies linearly, as increasing x. From the result of the Mossbauer spectroscopic study, it is found, that the magnetic properties of Ni?Cd?Fe?O? change from ferrimagnetism to paramagnetism as increasing x, and the Ni?Cd?Fe?O? have the Yafet-Kittel magnetic structure.

Mo¨ssbauer 분광법에 의한 Mg-Cd 페라이트계의 자기적 성질 연구

홍치유,최달하,문용식,백승도 東國大學校 1988 論文集 Vol.27 No.-

In this study, the magnetic properties of Mg_(1-X)Cd_(X)Fe₂O₄ ferrite system has been studied by Mo‥ssbauer spectroscopy. All the samples, prepared by a ceramic sintering method, were found to be single phase spinel by X-ray diffractometry. The Mo‥ssbauer spectra. for x<=0.3, show two magnetic hyperfine splittings. one due to Fe^3+ octahedral site ions and the other due to tetrahedral site ions. While for x=0.4 spectrum shows relaxation behaviour and for x>=0.5 it exhibits quadrupole splittings. This result implicates that the magnetic properties of Mg_(1-X)Cd_(X)Fe₂O₄ferrite system change from ferrimagnetics to paramagnetics as increasing x, And the x, Cd content, dependence of Mo‥ssbauer parameters (isomer shift, quadrupole splitting, magnetic hyperfine field and line width) were investigated.