• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.829-838
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• 2007

The stochiometric mix of evaporating materials for the $CdGa_2Se_4$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CdGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $630^{\circ}C$ and $420^{\circ}C$, 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 $CdGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $8.27{\times}10^{17}\;cm^{-3},\;345\;cm^2/V{\cdot}s$ at 293 K. respectively. The temperature dependence of the energy band gap of the $CdGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $Eg(T)\;=\;2.6400\;eV\;-\;(7.721{\times}10^{-4}\;eV/K)T^2/(T+399\;K)$. After the as-grown single crystal $CdGa_2Se_4$ thin films were annealed in Cd-, Se-, and Ga -atmospheres, the origin of point defects of single crystal $CdGa_2Se_4$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. We concluded that the heat-treatment in the Cd-atmosphere converted single crystal $CdGa_2Se_4$ thin films to an optical p-type. Also, we confirmed that Ga in $CdGa_2Se_4/GaAs$ did not form the native defects because Ga in single crystal $CdGa_2Se_4$ thin films existed in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.66-66
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• 2008

본 연구에서는 ITO/Ag/ITO 다층 박막을 유기발광소자와 플렉시블 광전소자의 전극으로 적용하기 위하여 선형 대항 타겟 스퍼터(Linear facing target sputter) 시스템을 이용하여 성막하였고, ITO/Ag/ITO 다층박막의 전기적, 광학적, 구조적 특성을 분석하였다. 선형 대항 타겟 스퍼터 시스템은 강한 일방항의 자계와 타겟에 걸린 음극에 의해 전자의 회전, 왕복 운동이 가능해 마주보는 두 ITO 타겟 사이에 고밀도의 플라즈마를 구속 시켜 플라즈마 데미지 없이 산화물 박막을 성막시킬 수 있는 장치이다. 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO 전극을 DC power, working pressure, Ar/O2 ratio 에 따른 특성을 각각 분석하였다. glass 기판위에 최적화된 ITO 전극을 bottom layer로 두고, bottom ITO layer 위에 thermal evaporation 을 이용하여 Ag 박막을 6~20nm의 조건에 따라 두께를 다르게 성막하고, Ag 박막을 성막한 후에 다시 bottom ITO 전극과 같은 조건으로 ITO 전극을 top layer로 성막 하였다. 두 비정질의 ITO 전극 사이에 매우 앓은 Ag 박막을 성막 함으로 해서 glass 기판위에 ITO/Ag/ITO 다층 박막전극은 매우 낮은 저항과 높은 투과도를 나타낸다. ITO/Ag/ITO 박막의 전기적 광학적 특성을 보기 위해 hall measurement와 UV/visible spectrometer 분석을 각각 진행하였다. ITO/Ag/ITO 다층 박막 전극이 매우 얇은 두께임에도 불구하고 $4\Omega$/sq.의 낮은 면저항과 85%의 높은 투과도를 나타내는 이유는 ITO/Ag/ITO 전극 사이에 있는 Ag층의 표면 플라즈몬 공명 (SPR) 현상으로 설명할 수 있다. ITO/Ag/ITO 전극의 Ag의 거동을 분석 하기위해 FESEM분석과 synchrotron x-ray scattering 분석을 하였다. ITO/Ag/ITO 전극의 Ag층이 islands의 모양에서 연속적으로 연결되는 변화과정 중에 SPR현상이 일어남을 알 수 있다. 여기서, 대항 타겟 스퍼터 시스템을 이용하여 성막한 ITO/Ag/ITO 다층박막을 OLED 또는 inverted OLEDs의 top 전극으로의 적용 가능성을 보이고 있다.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.2
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• pp.387-413
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• 1998

Image resampling is of particular interest in digital radiology. When resampling an image to a new set of coordinate, there appears blocking artifacts and image changes. To enhance image quality, interpolation algorithms have been used. Resampling is used to increase the number of points in an image to improve its appearance for display. The process of interpolation is fitting a continuous function to the discrete points in the digital image. The purpose of this study was to determine the effects of the seven interpolation functions when image resampling in digital periapical images. The images were obtained by Digora, CDR and scanning of Ektaspeed plus periapical radiograms on the dry skull and human subject. The subjects were exposed to intraoral X-ray machine at 60kVp and 70 kVp with exposure time varying between 0.01 and 0.50 second. To determine which interpolation method would provide the better image, seven functions were compared; (1) nearest neighbor (2) linear (3) non-linear (4) facet model (5) cubic convolution (6) cubic spline (7) gray segment expansion. And resampled images were compared in terms of SNR(Signal to Noise Ratio) and MTF(Modulation Transfer Function) coefficient value. The obtained results were as follows ; 1. The highest SNR value(75.96dB) was obtained with cubic convolution method and the lowest SNR value(72.44dB) was obtained with facet model method among seven interpolation methods. 2. There were significant differences of SNR values among CDR, Digora and film scan(P<0.05). 3. There were significant differences of SNR values between 60kVp and 70kVp in seven interpolation methods. There were significant differences of SNR values between facet model method and those of the other methods at 60kVp(P<0.05), but there were not significant differences of SNR values among seven interpolation methods at 70kVp(P>0.05). 4. There were significant differences of MTF coefficient values between linear interpolation method and the other six interpolation methods (P< 0.05). 5. The speed of computation time was the fastest with nearest -neighbor method and the slowest with non-linear method. 6. The better image was obtained with cubic convolution, cubic spline and gray segment method in ROC analysis. 7. The better sharpness of edge was obtained with gray segment expansion method among seven interpolation methods.

• Progress in Medical Physics
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• v.26 no.4
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• pp.223-228
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• 2015

Double-focused micro-Multileaf Collimator (${\mu}MLC$) is able to create radiation fields having sharper dose gradients at the field edges than common MLC. Therefore, ${\mu}MLC$ has been used for the stereotactic radiosurgery (SRS) and Stereotactic Radiotherapy (SRT). We evaluated the dosimetric characteristics of a doublefocused Dynamic-${\mu}MLC$ (DMLC) attached to the Elekta Synergy linear accelerator. For this study, the dosimetric parameters including, Percent Depth Dose (PDD), Leaf leakage and penumbra, have been measured by using of the radiochromic films (GafChromic EBT2), EDGE diode detector and three-dimensional water phantom. All datas were measured on 6 MV x-ray. As a result, The DMLC shows transmission below to 1% and because of double-focused construction of the DMLC, the penumbras of fields with DMLC are independent from the field sizes. In this paper, the resulting dosimetric evaluations proved the applicability of the DMLC attached to the Elekta Synergy linear accelerator.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.9
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• pp.611-615
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• 2001

Y$_2$O$_3$ thin films have been proposed as a buffering insulator of metal/ferroelectric/insulator/semiconductor field effect transistor(MFISFET)-type ferroelectric random access memory (FRAM). In this study, $Y_2$O$_3$ thin films were etched with inductively coupled plasma(ICP). The etch rates of $Y_2$O$_3$ and YMnO$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were investigated by varying Cl$_2$/(Cl$_2$＋Ar) gas mixing ratio. The maximum etch rate of $Y_2$O$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were 302$\AA$/min, and 2.4 at Cl$_2$/(Cl$_2$＋Ar) gas mixing ratio of 0.2 respectively. Optical emission spectroscopy(OES) was used to understand the effects of gas combination on the etch rate of $Y_2$O$_3$ thin film. The surface reaction of the etched $Y_2$O$_3$ thin films was investigated by x-ray photoelectron spectroscopy (XPS). XPS analysis confirmed that there was chemical reaction between Y and Cl. This result was confirmed by secondary ion mass spectroscopy(SIMS) analysis.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.51-57
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• 2014

The evaporating materials for $MgGa_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $MgGa_2Se_4$ compounded polycrystal powder was deposited on thoroughly etched semi-insulated GaAs(100) substrate by the hot wall epitaxy (HWE) method system. The source and substrate temperatures of optimized growth conditions, were $610^{\circ}C$ and $400^{\circ}C$, respectively.The source and substrate temperatures were $610^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by double crystal X-ray diffraction (DCXD). The temperature dependence of the energy band gap of the $MgGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=2.34\;eV-(8.81{\times}10^{-4}\;eV/K)T^2/(T+251\;K)$. After the as-grown $MgGa_2Se_4$ single crystal thin films was annealed in Mg-, Se-, and Ga-atmospheres, the origin of point defects of $MgGa_2Se_4$ single crystal thin films has been investigated by the photoluminescence (PL) at 10 K. The native defects of $V_{Mg}$, $V_{Se}$ obtained by PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the Se-atmosphere converted $MgGa_2Se_4$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $MgGa_2Se_4$/GaAs did not form the native defects because Ga in $MgGa_2Se_4$ single crystal thin films existed in the form of stable bonds.

• Journal of Chest Surgery
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• v.6 no.1
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• pp.15-22
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• 1973

The definition of cancer, its diagnosis and its prognosis all depend upon description of growth. To the layman a synonym for cancer is a "growth". There are no quantitative terms for the description of growth or growth rate in clinical use. There has been no attempt to assign values that would define "rapidly" or "slowly" growing. Estimates of growth potentiality are implied in the descriptive phrases "poorly differentiated" or "well differentiated", "highly malignant" or "low grade malignancy". and in systems of grading. These qualifying terms represent a personal impression, clinically useful in prognosis, but relative in nature. They do not lend themselves to uniform application or precise measurement for purpose of comparison. Growth is related to size and time. The volume of tumor depends upon the duration of the period of growth and the rate of growth. If the interval and change in volume are known. the average growth rate can be determined. If the growth rate is determined, and assumed to be constant., the duration of a given tumor and the time of inception can be estimated. The commonest concept of the origin of cancer is that as a result of a mutation involving a single cell, succeeding divisions of cells establish a colony with the characteristics recognizable as cancer. If the growth rate of the hypothetical tumor were constant it could be described in terms of "tumor volume doubling time". In the department of thoracic surgery of St. Mary hospital in Catholic Medical College, a clinical evaluation for the growth rate, degree of malignancy, resectability and prognosis was done on a total 24 cases of primary bronchogenic carcinoma which contour was significant on the chest X-ray film as possible estimating the tumor volume doubling time. The following results were obtained: 1. In the cases of 6.0cm or more in diameter of minor size at operation the resectability rate was lower and in the cases of 60 days or more in the tumor or volume doubling time the resectability rate was higher. 2. If differentiation of cancer cells was lower graded in tissue pathology, the tumor volume was shorter and the resectability rate was lower. 3. The tumor volume doubling time of the primary bronchogenic carcinoma occured more over 60 years of age was slightly shorter than under 60 years of age. 4. The tumor size at operation was more important to evaluate the survival time and prognosis than the tumor volume doubling time because the tumor growth was not always constant, we presume.mor volume doubling time because the tumor growth was not always constant, we presume.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.602-609
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• 1993

Lymphocytic interstitial pneumonitis (LIP) is one of parenchymal pulmonary infiltrative diseases first described at 1966 by Carrington and Liebow. In LIP, there is a predominance of mature small lymphocytes in the interstitium of the lung which form germinal centers. The disease process surrounds, but dose not invade lung parenchyme, tracheobronchial tree and vascular structures. The etiology remains still unknown and the clinical features of this disorder have not been clearly defined. Therefore, the therapeutic modality is obscure. Development of LIP association with AIDS is often reported currently and possibility of progress to malignant lymphoma is emphasized. We experienced a case of primary LIP with pnemomediastinum. She was adimitted due to chest and anterior nuchal pain with chronic coughing, and diagnosed as pneumomediastinum with LIP. Medication with steroid was begun and some improvement of symptoms was observed, but an X-ray film of the chest remained same without improvement. We report above case with review of the literatures.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.104-109
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• 2005

To study the role of PbO as the buffer layer, Pt/PZT/PbO/Si with the MFIS structure was deposited on the p-type (100) Si substrate by the r.f. magnetron sputtering with $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ and PbO targets. When PbO buffer layer was inserted between the PZT thin film and the Si substrate, the crystallization of the PZT thin films was considerably improved and the processing temperature was lowered. From the result of an X-ray Photoelectron Spectroscopy (XPS) depth profile result, we could confirm that the substrate temperature for the layer of PbO affects the chemical states of the interface between the PbO buffer layer and the Si substrate, which results in the inter-diffusion of Pb. The MFIS with the PbO buffer layer show the improved electric properties including the high memory window and low leakage current density. In particular, the maximum value of the memory window is 2.0V under the applied voltage of 9V for the Pt/PZT(200 nm, $400^{\circ}C)/PbO(80 nm)/Si$ structures with the PbO buffer layer deposited at the substrate temperature of $300^{\circ}C$.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.535-546
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• 1996

The purpose of this study was to classify mandibular dental arch forms based on Raberin's method, and to compare Raberin's arch forms with that of the Korean's, and to designate arch form of bracket level according to distance between cusp tip and buccal surface of bracket level. The sample consisted of 159 mandibular dental casts showing normal occlusion which was taken from 62 males and 97 females of the Korean, aging from 13 to 25 years. The model was taken by X-ray. The landmarks were cusp points which expressed the mandibular dental arch line of cusp tips and buccal points which were measured from cusp tips to buccal surfaces of bracket level. The landmarks on the film were digitized, and measurements and statistics were performed. The results were as follows; 1. The models were classified as type 1, type 2, type 3, type 4 and type 5 by the author, and polynomial functions of the six degree and R-square values were calculated using statistical method, and each calculated equations explained each group with the least R-square value of 0.97, and each arch forms' were plotted. 2. The distribution of type 1 was $17.6\%$, type 2 $20.8\%$, type 3 $20.8\%$, type 4 $16.3\%$ and type 5 $24.5\%$. 3. The Korean arch form was characterized by larger width, smaller height compared to the French arch form. 4. The designated arch form of bracket level, viz the distance between cusp point and buccal point was calculated. The distance between cusp point and buccal point of incisor was 1mm, canine 1.9mm, first premolar 2.5mm, second premolar 2.6mm, first molar 2.7mm and second molar 2.7mm.