• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.93-95
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• 2012

We report on the growth and characterization of the nano- and micro scale GaN structures selectively grown on the vertex of GaN stripes using the metal organic vapor phase epitaxy method and conventional photolithography technique. The triangular shaped nano- and micro GaN structures which have semi-polar {11-22} facets were formed only on the vertex of the lower GaN stripes. Crystalline defects reduction was observed by transmission electron microscopy for upper GaN stripes. We also have grown the InGaN/GaN multi-quantum well structures on the semi-polar facets of the upper GaN stripes. Cathodoluminescence images were taken at 366, 412 and 555 nm related to GaN band edge, InGaN/GaN layer and defects, respectively.

• 한국조경학회지
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• 제38권4호
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• pp.106-127
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• 2010

최근 생태환경 조성을 위한 다층구조 식재는 식생복원 등 환경사업뿐만 아니라 군락식재의 방법으로서 활용이 확산되고 있으나, 실제 조경 식재 설계에 있어 다층식재 기법을 활용하는 데에는 어려움이 있었다. 본 연구는 서울지역의 숲 구조를 분석하여 다층식재 시 활용 가능한 기초적 다층 식재모델 개발을 목적으로 하고 있다. 이를 위해 생태분석프로그램인 PC ORD 4.0(MjM Soft, 2002) 프로그램을 활용, ISA(Indicator Species Analysis) 분석을 통한 적정 군집수를 설정하여 군집분석을 실시하였다. 그 결과 상수리나무군락, 신갈나무-팔배나무군락, 소나무-리기다소나무군락, 신갈나무-진달래군락, 선갈나무-노간주나무군락, 소나무-진달래군락, 선갈나무-철쭉나무군락 등의 7개의 자연 식생군락으로 분석되었다. 그리고 대상지에 출현한 빈도 10% 이상의 식물종간의 종간친화력 검정을 통하여, 자연식생에서의 수반종과 함께 수급 및 유통이 가능한 대체 유사종을 제시함으로써 활용도를 높였다. 위의 결과를 종합한 7개 자연식생군락을 기초로 하여, 군락 내 종간 친화력이 있는 식물종을 재선정하여 조경 식재 설계 시 활용할 수 있는 다층식재 모델을 제안하였다. 개발된 다층식재 모델은 변환우점도 값의 평균값을 기준으로 하여 평균 목표피도를 제시함으로써 식재설계 시 폭넓게 응용할 수 있도록 하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 봄 학술발표회 논문집
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• pp.58-64
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• 1992

It is usual that underground structures are constructed within multi-layered medium. In this paper, an efficient numerical model ling of multi-layered structural systems is studied using coupled analysis of finite elements and boundary elements. The finite elements are applied to the area in which the material nonlinearity is dominated, and the boundary elements are applied to the far field area where the nonlinearity is relatively weak. In the boundary element model 1 ins of the multi-layered medium, fundamental solutions are restricted. Thus, methods which can utilize existing Kelvin and Melan solution are sought for the interior multi-layered domain problem and semi infinite domain problem. Interior domain problem which has piecewise homogeneous layers is analyzed using boundary elements with Kelvin solution; by discretizing each homogeneous subregion and applying compatibility and equilibrium conditions between interfaces. Semi-infinite domain problem is analyzed using boundary elements with Melan solution, by superposing unit stiffness matrices which are obtained for each layer by enemy method. Each methodology is verified by comparing its results which the results from the finite element analysis and it is concluded that coupled analysis using boundary elements and finite elements can be reasonable and efficient if the superposition technique is applied for the multi-layered semi-infinite domain problems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.725-730
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• 2007

A framework of multi layered database is proposed for the integrated operation of civil infrastructure information in this study. The multi-layered database is a logically integrated database composed of standardized information layers. The framework of multi-layered database is defined by three axes, national assets, lifetime, and data levels. The axis of national assets indicates civil infrastructures such as bridges, dams, tunnels and power plants that can be considered as national key structures. The axes of lifetime and data levels indicate the standardized information layers generated from the life-phase of civil infrastructure and the priority of data in the information layers, respectively. The standardized information layers are basically composed of reusable data sets defined by information models. A prototype of standard database for steel bridges is constructed based on the framework as a proof of concept. Demonstration examples such as data consistency check and automatic generation of a FEA model show that the proposed concept can assure the sustainable interoperability of civil infrastructure information as well as design information of steel bridges.

• 한국도로학회논문집
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• 제7권3호
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• pp.11-21
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• 2005

본 연구에서는 기존의 아스팔트 콘크리트 포장구조해석에 사용되는 다층탄성해석에서 경계면의 영향을 평가하기 위해 상용 유한요소해석 프로그램인 ABAQUS와 다층탄성 프로그램인 KENLAYER를 이용하여 연직하중이 작용하는 경우의 경계면 특성에 따른 포장성능에 관한 비교 분석을 실시하였다. 그리고 실제 주행하중에 의해 발생되는 수평하중이 포장체에 미치는 영향을 고찰하기 위해 수평하중을 고려한 포장구조해석도 실시하였다. 이를 위해 ABAQUS를 이용하여 경계면 상태에 따른 포장구조체 내부에서 발생하는 변형률 및 처짐을 분석하고, 경계면의 접합상태에 따른 효과를 분석하였다. 이러한 과정을 통해 경계면 상태에 따른 포장체의 공용성에 관한 기존의 정성적 평가로부터 수치해석을 통해 정량적 평가를 실시하고, 경계면 효과에 대한 기본연구를 실시하였다. 연구 결과 기존 해석에서 사용되는 연직하중만 작용하는 경우와 실제 주행하중을 모사하는 연직하중과 수평하중이 동시에 작용하는 경우 수평하중의 작용으로 인해 공용횟수가 약 1/300로 감소하여 포장구조해석시 수평하중을 고려한 해석이 절실히 필요함을 알 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.871-874
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• 1998

A new transmission line parameter extraction method of iC interconnects on silicon substrate is presented. To extract the acurate parameters, the silicon substrate effects were taken into account. Since the electromagnetic fields under the silicon substrate are propagated with slow wave mode, effective dielectric constant and different ground plane with the multi-layer dielectric structures were employed for inductance and capacitance matrix determination. Then accurate signal transients simulation were performed with HSPICE by using the parameters. It was shown that the simulation resutls has an excellent agreement with TDR/TDT measurements.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.462-462
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• 2000

In this paper, genetic algorithm (GA) is the technique to search for the optimal structures (i,e., the kind of neural network, the number of hidden neuron, ..) of the neural networks which are used approximating a given nonlinear function, In this paper, we used multi layer feed-forward neural network. The decision method of synapse weights of each neuron in each generation used back-propagation method. In this study, we simulated nonlinear function approximation in the temperature control system.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.150.2-150.2
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• 2015

In this study, we analyzed the electric and optical characteristics by using various deposition rate ($0.5{\AA}$, $1.0{\AA}$ and $1.5{\AA}/s$) in order to enhance the performance in organic light-emitting devices (OLED). The organic multi-layer structures were deposited with NPB ($500{\AA}$ as hole transport layer), Alq3 ($600{\AA}$ as electron transport layer and emission layer) and LiF ($8{\AA}$ as electron injection layer) via SUNIC PLUS200 on Glass/ITO substrates. In this experiment, we examined the relationship between porous state of organic deposition and mobility of the organic materials. Among the three deposition rates, $0.5{\AA}/s$ achieved the highest performance of (10,786cd/m2, 4.387cd/A) comparing with that of $1{\AA}/s$ (7,779cd/m2, 3.281cd/A) and $1.5{\AA}/s$ (5,167cd/m2, 2.693cd/A). We confirmed that low deposition rate helps to arrange organic materials densely and to move easily another atomic location using inter-chain transporting by orbital overlap.

• Applied Science and Convergence Technology
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• 제24권2호
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• pp.33-40
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• 2015

$ZrO_2$ and Al-Zr composite oxide film was prepared by vacuum assisted sol-gel dip coating method and anodizing. $ZrO_2$ films annealed above $400^{\circ}C$ have tetragonal structure. $ZrO_2$ layers inside etch pits were successfully coated from the $ZrO_2$ sol. The double layer structures of samples were obtained after being anodized at 100 V to 600 V. From the TEM images, it was found that the outer layer was $Al_2O_3$, the inner layer was multi-layer of $ZrO_2$, Al-Zr composite oxide and Al hydrate. The capacitance of $ZrO_2$ coated foil exhibited about 28.3% higher than that of non-coating foil after being anodized at 100 V. The high capacitance of $ZrO_2$ coated foils anodized at 100 V can be attributed to the relatively high percentage of inner layer in total thickness. The electrical properties, such as withstanding voltage and leakage current of coated and non-coated Al foils showed similar values. From the results, $ZrO_2$ and Al-Zr composite oxide is promising to be used as the partial dielectric of high voltage capacitor to increase the capacitance.

• 한국자기학회지
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• 제10권6호
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• pp.274-279
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• 2000

본 연구에서는 D.C 마그네트론 스퍼터링을 사용하여 Mn-Ir/Ni-Fe교환결합형 다층박막의 하지층 및 적층구조에 따른 자기적 특성 및 열적 특성을 미세구조의 관점에서 연구하였다. 교환결합자계( $H_{ｅ{\chi}}$)와 Blocking Temperature( $T_{b}$)는 Mn-Ir/Ni-Fe 계면에서의 반강자성체의 결정립 크기에 의존하는 것을 알 수 있었다. 또한 Mn-Ir/Ni-Fe 교환결합형 다층박막에서 (111) 우선방위의 발생으로 인하여 $H_{e{\chi}}$가 증가됨을 알 수 있었다. $H_{e{\chi}}$가 발생하는 Mn-Ir/Ni-Fe 다층박막은 Mn-Ir 층에 전위가 생성되어 grain-to-grain epitaxy 관계가 이루어지는 것을 알 수 있었다.다.