• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.275-276
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• 2011

We have investigated the holographic grating formation on Ag-doped amorphous chalcogenide As2Se3 thin films with Ag layer. The basic optical parameter which is a refractive index and extinction coefficent was taken by n&k analyzer. The source of laser was selected based on these parameter. Holographic gratings have been formed using He-Ne laser (wavelength: 632.8 nm) Diode Pumped Solid State laser (DPSS, wavelength: 532.0 nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.215-219
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• 2001

NaY Zeolite를 Autoclave의 자생압력하에 90℃에서 6-36시간 수열 합성법에 의해 합성하였다. 합성된 NaY Zeolite는 1-2㎛의 크기를 갖는 octahedral 구조이고, 격자상수(a)는 23.9230인 NaY zeolite가 단일상으로 합성되었다. SiO₂/Al₂O₃의 몰비는 NaY type인 3.65이고, 상용 NaY zeolite의 BET(509.3㎡/g)에 비하여 Muti- point BET가 약 607.2로 100㎡/g 증가하였고, Pore volume은 0.2416cc/g에 비하여 0.3149cc/g로 증가하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.32-36
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• 2021

This study was investigated in carbon diffusion behavior of laser-carburized TiZrN coating layer and the changes of mechanical properties. The carbon paste was deposited on TiZrN coatings, and the laser was irradiated to carburize into the coatings. The XRD peak corresponding to the (111) plane shifted to a lower angle after the carburization, showing the lattice expansion by doped carbon. The decreased grain size implied the compression by the grain boundary diffusion of carbon. The XPS spectra for the bonding states of carbon was analyzed that carbon was substitute to nitrogen atoms in TiZrN, as carbide, through the thermal energy of laser. In addition, the combination of sp2 and sp3 hybridized bonds represented the formation of an amorphous carbon. The cross-sectional TEM image and the inverse FFT of the TiZrN coating after carburizing were observed as the wavy shape, confirming the amorphous phase located in grain boundaries. After the carburization, the hardness increased from 34.57 GPa to 38.24 GPa, and the friction coefficient decreased by 83 %. In particular, the ratio of hardness and elastic modulus (H/E) which is used as an index of the elastic recovery, increased from 0.11 to 0.15 and the wear rate improved by 65 %.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.2
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• pp.437-461
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• 2011

The purpose of this study was to examine the metacognition of mathematically gifted students in the problem-solving process of the given task in a bid to give some significant suggestions on the improvement of their problem-solving skills. The given task was to count the number of regular squares at the n${\times}$n geoboard. The subjects in this study were three mathematically gifted elementary students who were respectively selected from three leading gifted education institutions in our country: a community gifted class, a gifted education institution attached to the Office of Education and a university-affiliated science gifted education institution. The students who were selected from the first, second and third institutions were hereinafter called student C, student B and student A respectively. While they received three-hour instruction, a participant observation was made by this researcher, and the instruction was videotaped. The participant observation record, videotape and their worksheets were analyzed, and they were interviewed after the instruction to make a qualitative case study. The findings of the study were as follows: First, the students made use of different generalization strategies when they solved the given problem. Second, there were specific metacognitive elements in each stage of their problem-solving process. Third, there was a mutually influential interaction among every area of metacognition in the problem-solving process. Fourth, which metacognitive components impacted on their success or failure of problem solving was ascertained.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.227-227
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• 2013

본 연구에서는 Si(111) 기판에 성장온도 및 InN 증착양 변화에 따른 InN 양자점(Quantum Dot) 핵성생(Nucleation) 특성에 대해 논의한다. InN 양자점은 Nitrogen-Plasma 소스를 장착한 분자선증착기(MBE)를 이용하여 $0.103{\AA}/s$의 성장속도로 성장하였다. 성장온도를 $700^{\circ}C$에서 $300^{\circ}C$로 변환하면서 형성한 시료에서 lnN 양자점의 공간밀도는 $9.4{\times}10^7/cm^2$부터 $1.1{\times}10^{11}/cm^2$를 나타냈다. 가장 높은 공간밀도인 $1.1{\times}10^{11}/cm^2$는 기존에 보고된 값 ($7.7{\times}10^{10}/cm^2$)보다 상대적으로 높은 값을 갖는다 [1,2]. InN 증착양을 93, 186, 및 $372{\AA}/s$으로 각각 변화시켜 형성하여 양자점의 초기 성장거동을 분석하였다. InN 증착양이 증가함에 따라 양자점의 공간밀도는 $4.4{\times}10^{10}/cm^2$에 $6.4{\times}10^{10}/cm^2$까지 증가하였다. 일반적으로 InP 및 GaAs 기판을 기반으로 한 In(Ga)As 양자점은 증착양이 증가함에 따라 밀도는 감소하고 크기는 증가하는 경향을 보이며, 이는 같은 상 (Phase)을 갖는 물질들끼리 결합하려는 경향이 있기 때문이다. 본 실험에서는 기존 결과와 다른 경향을 보이고 있는데, 이는 Si(111) 기판과 InN 사이의 격자부정합이 상대적으로 크기 때문에 InN 양자구조가 커지는 대신 추가로 새로운 핵생성 메커니즘에 의한 것으로 설명할 수 있다. 이러한 InN 증착양에 따른 InN 양자점 성장거동을 표면에너지를 포함한 이론적인 모델을 통해 논의하고자 한다.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.748-753
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• 1995

Solid solution of NaNb $O_3$70 mol% and SrTi $O_3$30 mol% was single phase. A broad dielectric peak was found at about l00K. Crystal structure was analysed at room temperature and 12K using Rietveld analysis. The unit cell was assigned to have a a doubled lattice parameter of simple perovskite sturcture at room temperatue, the structure was orthorombic with space group Pmmn. At 12K, the structure was also orthorombic with space group Pnma. This structure change with temperature was due to the distortion of oxygen octahedron. This distortion of oxygen octahedron was made by the decrease of (Ti, Nb)-O bounds length with no variation of (Ti, Nb)-O-(Ti, Nb) bound angle. Therefore the broad dielectirc peak about l00K was attributed to the structural change casued by oxygen octahedron distortion.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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• pp.47-53
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• 1998

Multi-dimensional DC-free trellis codes based on two-dimensional constellation which can be omplemented more easily than conventional codes are proposed and their performances are analyzed in this paper. 2N-dimensional constellation of the proposed codes is constructed by concatenating N 2-dimensional constellation. Thus, for the proposed codes, information bits can be assigned easily to each signal point of the 2-dimensional consteellation and DC-free characteristic can be simply obtained by the symmetric structure of the constellation. In addition, since Viterbi decoder can calculate multi-dimensional Euchlidean distance between signals by simple sum of each 2-dimensional Euclidean distanc, decoding complexity can be reduced. The performance analysis shows that the proposed codes have almost same spectral characteristic and error performance as compared with conventional codes. However, the complexity is shown to be reduced further due to the construction method of contellation and the simple decoding algorithm of the proposed codes.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1830-1832
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• 1999

고에너지 이온주입(1)에 기인한 격자 손상 발생 및 열처리에 따라 이들의 회복이 어느정도 가능한지에 대하여 측정 및 분석방법을 통하여 조사하였다. 그리고 본 실험에서는 이온주입시 형성되는 빈자리 결함(Vacancy defect)과 격자간 결함(interstitial defect)의 재결할(recombination)을 이용 점결합(point defect)를 감소 시킬 수 있는 effective RTA조건을 설정하여 well 특성을 개선하고자 하였다. 8inch p-type Si(100)기판에 pad oxide 100A을 형성한 후 NMOS 형성하기 위해 vtn${\sim}$p-well과 PMOS 형성을 위해 vtp$\sim$n-well을 이온주입 하였다. Mev damage anneal은 RTA(2)(Rapid Thermal Anneal)로 $1000\sim1150C$ 온도에서 $15\sim60$초간 spilt 하여 실험후 suprem-4 simulation data를 이용하여 실제 SIMS측정 분석결과를 비교하였으며 이온주입에 의해 발생된 격자손상이 열처리후 damage 정도를 알아보기 위해 T.W(Therma-Wave)을 이용하였으며 열처리후 면저항값은 4-point probe를 사용하였다. 이온주입후 열처리 전,후에 따른 불순물 분포를 SIMS(Secondary ion Mass Spectrometry)를 이용하여 살펴보았다. SIMS 결과로는 열처리 온도 및 시간의 증가에 따라서 dopant확산 및 활성화는 큰차이는 보이지 않고 오히려 감소하는 경향을 볼 수 있으며 또한 접합깊이와 농도가 약간 낮아지는 것을 볼 수 있었다. 결점(defect)을 감소시키기 위해서 diffusivity가 빠른 임계온도영역($1150^{\circ}C$-60sec)에서 RTA를 실시하여 dopant확산을 억제하고 점결점(point defect)의 재결합(recombination)을 이용하여 전위 (dislocation)밀도를 감소시켜 이온주입 Damage 및 면저항을 감소 시켰다. 이와 같은 특성을 process simulation(3)(silvaco)을 통하여 비교검토 하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.49-54
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• 2021

In this paper, n this paper, E-polarized electromagnetic scattering problems by a resistive strip grating between a double dielectric layer are analyzed by applying the PMM(Point Matching Method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, and the resistive boundary condition is applied to analysis of the resistive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the relative permittivity and thickness of the double dielectric layers, and the resistivity of resistive strip. Overall, when the resistivity of the resistive strip decreased or the relative permittivity of the dielectric layer increased, the reflected power increased, and as the reflected power increased, the transmitted power decreased relatively. Especially, as the relative permittivity of double dielectric layer increases, the minimum value of the variation curve of the reflected power shifted in the direction that the grating period decreased. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers.

• Journal of the Korean Vacuum Society
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• v.20 no.1
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• pp.22-29
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• 2011

An infrared thermographic imaging module of [$320{\times}256$] focal-plane array (FPA) based on [InAs/GaSb] strained-layer superlattice (SLS) was fabricated, and its images were demonstrated. The p-i-n device consisted of an active layer (i) of 300-period [13/7]-ML [InAs/GaSb]-SLS and a pair of p/n-electrodes of (60/115)-period [InAs:(Be/Si)/GaSb]-SLS. FTIR photoresponse spectra taken from a test device revealed that the peak wavelength (${\lambda}_p$) and the cutoff wavelength (${\lambda}_{co}$) were approximately $3.1/2.7{\mu}m$ and $3.8{\mu}m$, respectively, and it was confirmed that the device was operated up to a temperature of 180 K. The $30/24-{\mu}m$ design rule was applied to single pixel pitch/mesa, and a standard photolithography was introduced for [$320{\times}256$]-FPA fabrication. An FPA-ROIC thermographic module was accomplished by using a $18/10-{\mu}m$ In-bump/UBM process and a flip-chip bonding technique, and the thermographic image was demonstrated by utilizing a mid-infrared camera and an image processor.