Determination of the Al mole fraction in epitaxial AlxGa1-xN/GaN (x < 0.25) Heterostructures

반승일,C. M. Lee,S. J. Lee,J. I. Lee,C. S. Kim,노삼규,오병성,K. J. Kim 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.43 No.I

We have used the X-ray diffractometry (XRD), photoluminescence (PL) spectroscopy, and X-ray photoemission spectroscopy (XPS) to determine the Al mole fraction in Al$_x$Ga$_{1-x}$N/GaN ($x$ $<$ 0.25) heterostructures. The Al compositions, $x$, determined by XRD and PL are in good agreement within an error of $\pm$0.02, and the XRD values are a little smaller than the PL values, which is due to partial strain relaxation of the AlGaN layers, particularly for high Al contents. In addition, the XPS data reveal that the low-$x$ values are fairly consistent with the other values obtained by using XRD and PL, but the high-$x$ values digressed considerably from those values, which indicates that the XPS spectra does not give correct values for AlGaN films with high Al contents, probably due to spatial alloy fluctuations.

長管骨의 外傷性 骨缺損에 對한 治療

潘勝一(Ban Seung Il),曺晋煥(Cho Jin Hwan) 대한정형외과학회 1973 대한정형외과학회지 Vol.8 No.4

6 가 크롬이 백서의 배양섬유모세포에 미치는 세포독성에 관한 연구

강영,반승일,김양일,김형주,정연태 원광대학교 환경과학연구소 1992 環境科學硏究誌 Vol.1 No.1

To investigate the cytotoxicity of Cr^6+, the colorimetric assays of neutral red (NR) and tetrazolium MTT, the measurements of the protein content and the rate of DNA synthesis, and sister chromatid exchange(SCE) analysis were performed in fibroblasts cultured in the medium containing various concentrations of Cr^6+. Electron microscopy of Cr^6+ treated rat fibroblasts was also carried out. The results were as follows ; 1. NR uptake was decreased dose-dependently and NR_90 and NR_50 values of Cr^6+ were 0.2 μM and 1.7μM respectively. 2. Cr^6+ induced the dose-dependent decrease of the activity of mitochondrial succinic dehydrogenase and MTT_90 and MTT_5o valyes were 0.5μM and 5.5 μM respectively. 3, Protein content in rat fibroblasts treated with Cr^6+ decreased dose-dependently. 4. Cr^6+ inhibited DNA synthesis dose-dependently and the rate of DNA synthesis at concentration of Cr^6+ 1.0μM(1.7μM, NR_50) was 33% of the control. 5. Frequency of sister chromatid exchange(SCE) increased dose-dependently and the frequency of sister chromatid exchange at concentration of Cr^6+ 1.0μM was noted to be 8.8 per cell. 6. Light microscopy revealed dose dependent reduction of cell number and decrease in cell size after Cr^6+ treatment. Electron microscopy of cultured fibroblasts treated with Cr^6+ showed dilatation of cisternae of granular endoplasmic reticulum drastic decrease of polyribosomes and increase in number of lysosomes. Above results indicated that Cr^6+ induced severe toxic effect on cultured cell, and suggested that DNA damage by Cr^6+ can be resulted inhibition of cell growth and decrease in cell viability.

카드뮴이 백서의 배양섬유모세포에 미치는 세포독성에 관한 연구

유태환,반승일,김형주,김양일,정연태 원광대학교 환경과학연구소 1992 環境科學硏究誌 Vol.1 No.1

Present study was carried out to investigate the cytotoxicity of cadmium on cultured rat fibroblasts. The colorimetric assays of neutral red(NR) and tetrazolium MTT, the measurements of total contents of protein, the rated of DNA synthesis, light and electron microscopic studies were performed on the fibroblasts cultured in the media containing various concentrations of cadmium. The results are as follows : 1. The NR and MTT values were increased dose-dependent of cadmium. 2. The MR_90, MR_50, MTT_90 and MTT_50 values of cadmium were 0.2μM, 19.5μM, 1.0μM and 60.0μM, respectively. 3. The total contents of protein at concentrations of cadmium, 0.2μM, 24.5μM were 90% and 50% of the control, respectively. The aspects which decrease the total contents of protein agreed to NR uptake ability. 4. The rates of DNA synthesis at concentrations of cadmium, 5.0μM, 70.0μM were 90% and 50% of the control, and those were 65%, 60% at concentration of NR_50, MTT_50 values, respectively. 5. In light microscopic study, cadmium induced dose-dependent reduction of cell number and decrease in cell size, and election microscopy of cultured fibroblasts treated with cadmium showed dilatation of cisternae of granular endoplasmic reticulum. 6. Cadmium induced the toxic effects on the lysosome and mitochondria at lower concentration than does which didn't affect the rated of DNA synthesis.From the above results, it suggests that the cytotoxic target of cadmium may be cell organelles such as granular endoplasmic reticulum.

생쥐의 卵子와 初期胚子에 對한 Clomiphene Citrate의 細胞毒性에 關한 硏究

金惠敬,潘勝一,金洋一,文蓮子,朴承澤,鄭然泰 圓光大學校 醫科學硏究所 1993 圓光醫科學 Vol.9 No.1-2

In order to elucidate the cytotoxicity of clomiphene citrate, the rate of in vitro fertilization(IVF) of ova and the developmental rate of early embroys in A-strain mouse were examined. The rate of ova cleavaging to 2-cell stage by IVF was remarkably decreased(12.6%) at the concentration of 10μg/㎖ of clomiphene than that of the control(65.2%) when the ova fertilized in vitro were cultured for 24 hours in the untreated medium after treatment ova with clomiphene for 5 hrs. But there was no ovum cleavaging to 2-cell stage at 50μg/㎖ clomiphene except only a few 2-polar bodied ova. The developmental rate of mouse early embryos was decreased dose-dependently. Especially at 25μg/㎖ of clomiphene, the number of embryos cleavaging to blastocyst from 2-cell stage(41.4%) was decreased remarkably compared with that of the control(87.2%). And only a few embryos were developed to 8-cell stage at clomiphene concentration of 50μg/㎖ after 2-cell embryos were incubated for 72 hours in clomiphene-treated medium. Morphological changes such as fragmentation and fusion of blastomeres, cytolysis and developmental retardation were increased with dose-dependently. These results suggest that clomiphene has cytotoxic effect by the decrease of the rate of IVF, the developmental rate and the degenerative changes of murine ova and early embryos.

이온 보조 증착에 의한 ZnS 광학 박막의 광학적, 구조적 특성과 환경적 안정성 개선에 관한 연구

김형근,반승일,김석원,한성홍 한국광학회 1997 한국광학회지 Vol.8 No.1

Ar 이온 보조 증착(IAD)에 의해 제작된 ZnS 박막의 광학적 특성, 환경적 안정성, 결정성을 기존의 보통 박막과 비교 분석하였다. IAD 박막은 보통 박막에 비해 상대적으로 높은 굴절률과 낮은 소멸 계수를 나타내었고, 습도(85%)와 온도(150.deg. C)에 대한 안정성 테스트 결과 수분 감도와 온도 의존성이 현저히 감소되어 이들 환경에 대하여 안정성을 갖는 것으로 나타났다. 이러한 결과는 이온 충격에 의해 박막의 조밀도가 증가되어 내부 미세구조가 개선되므로 대기중의 수분 흡착 감소에 기인한 것으로 분석된다. 또한 X선 회절 실험 결과 보통 박막은 전형적인 박막의 비정질 구조를 나타낸 반면 IAD 박막은 결정질의 구조를 나타내었다. The optical property, the environmental stability and the crystallization of ZnS thin films prepared by ion-assisted deposition (IAD) were investigated and compared with those of conventional electron-beam deposited thin films. The humidity(R.H. 85%) test and the thermal(15$0^{\circ}C$) show that the IAD films have relatively higher refractive index, smaller extinction coefficient and environmentally more stable than the conventional films. It is believed to originate from the reduced adsorption of moisture which reflect the increased packing density and the improved microstructure by ion bombardment. XRD experiments also confirm that conventionally grown films have an amorphous in comparison with the crystalline structured IAD films.

Vinblastine이 백서 배양신경세포에 미치는 세포독성에 관한 연구

김대호,유태전,반승일,박승택,정연태 원광대학교 환경과학연구소 1992 環境科學硏究誌 Vol.1 No.1

To investigate the cytotoxicity of vinblastine for cultured neonatal rat neurons and astrocytes, inverted phase contrast microscopic study was performed for the primary cultured neurons and astrocytes in the media containing various concentrations of vinblastine. The results are as follows : 1. At a concentration of 1 X 10^-4mM vinblastine, neurites and fasciculi of neurons were reduced in number and showed bead were broken appearance. Cell clusters tend to float by the detachment from the culture surface and to form large aggregated cell masses. At a concentration of 3X 10^-4mM, degenerative changes of the neurons were markedly enhanced. Furthermore, dissociation and dispersion of dead neurons from the cell aggregates, and pyknosis and karyorrhexis of neurons were noted. 2. At a concentration of 5 X 10^-4mM vinblastine, astrocytes decreased in number and showed cytoplasmic vacuolization. At a concentration of 1 X 10^-3mM , these regressive changes of astrocytes were more pronounced and also astrocytes showed severe shrinkage and granulation. Above results indicate that vinblastine has the cytotoxic effect on cultured neurons and astrocytes of neonatal rat brain.

Quasi - monolayer {InAsm / GaAsn}층을 이용한 InAs 양자점의 에너지준위 조절

김종수,배인호,김구현,반승일,김진수,강세경,이주인,노삼규,임재영 한국진공학회 2001 한국진공학회 학술발표회초록집 Vol.- No.-

이온 보조 증착에 의해 제작된 MgF₂ - TiO₂ 혼합 박막의 광학적, 구조적 특성 분석

성창민(Chang Min Sung),반승일(Seung Il Ban),김형근(Hyeong Geun Kim),김석원(Sok Won Kim),한성홍(Sung Hong Hahn) 한국광학회 1997 한국광학회지 Vol.8 No.5

MgF₂와 TiO₂를 각각 다른 두 증발원으로부터 동시에 증착시켜 혼합 박막을 제작하였다. 박막의 특성을 개선시키기 위해 이온 보조 증착(IAD)을 하였다. 제작된 MgF₂-TiO₂ 혼합 박막의 원소 조성비, 광학적 특성과 결정 구조를 분석하였다. 상대적 증착률을 달리하여 제작된 MgF₂-TiO₂ 혼합 박막의 Mg:Ti의 조성비는 비선형적으로 변화하였으며 MgF₂의 조성비를 상대적으로 증가시킴에 따라 혼합 박막의 굴절률은 감소하였고 Drude 모델을 잘 만족함을 알 수 있었다. 그리고 MgF₂의 조성비가 증가할수록 비정질인 TiO₂ 구조 사이에 다결정질인 MgF₂의 양이 증가하여 결정성을 갖는 박막으로 성장함을 확인하였다. The composite MgF₂-TiO₂ films are fabricated by codepositon from two independent sources. To improve optical and mechanical properties of films, the films are prepared by ion-assisted deposition. Chemical compositions, optical properties and microstructures of the composite films were investigated. The chemical composition rates of Ti:Mg of MgF₂-TiO₂ composite films are nonlinearly varied according to the relative deposition rate. It is found that the refractive indices of the composite films decrease with increasing MgF₂ contents and can be fitted quite well with Drude's formula and that the microstructures of the composite films changes from an amorphous to crystalline with increasing MgF₂ mole fractions.

Structural Characterization of InGaN/GaN Multi-Quantum Well Structures Using High-Resolution XRD

김영훈,김창수,노삼규,반승일,김성구,임기영,오병성 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III

The structural properties of 10-period In$_{0.15}$Ga$_{0.85}$N/GaN multiple quantum wells (MQWs) have been investigated using HRXRD (high-resolution X-ray diffraction). For the samples, the barrier thickness was kept constant, 7.5 nm and the well thicknesses were varied, 1.5, 3.0, 4.5, and 6.0 nm. For the X-ray structural characterization, an $omega$/2$theta$-scan and an $omega$-scan for GaN (00$cdot$2) reflection and a reciprocal space mapping (RSM) around the GaN (10$cdot$5) lattice point were employed. The average strain for the MQWs increased as the well thickness increased. The MQW with a 6.0 nm well thickness experienced lattice relaxation and the crystallinity of the sample was poor compared to that of the other samples. MQWs with well thicknesses of 1.5, 3.0 and 4.5 nm, however, maintained lattice coherency with the GaN epilayers underneath, and the critical well thickness for lattice relaxation of the MQWs used in the study was 6.0 nm. The degree of relaxation along in-plane direction for the lattice relaxed MQW was about 2.8 %.