• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.116-120
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• 2011

In this paper, we studied the optimization of the screen pringting method for crystalline silicon solar cell fabrication. The 156 * 156 mm2 p-type silicon wafers with $200{\mu}m$ thickness and $0.5-3{\Omega}cm$ resistivity were used after texturing, doping, and passivation. Screen printing method is a common way to make the c-Si solar cell with low-cost and high-efficiency. We studied the optimized condition for screen printing with crystalline silicon solar cell as changing the printing direction (finger line or bus bar), finger width, and mesh angle. As a result, the screen printing with finger line direction showed higher finger height and better conversion efficiency, compared with one with bus bar direction. The experiments with various finger widths and mesh angles were also carried out. The characteristics of solar cells was obtained by measuring light current-voltage, optical microscope and electroluminescence.

• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.1005-1012
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• 2000

Numerical optimization techniques combined with a three-dimensional thin-layer Navier-Stokes solver are presented to find an optimum shape of a stator blade in an axial compressor through calculations of single stage rotor-stator flow. Governing differential equations are discretized using an explicit finite difference method and solved by a multi-stage Runge-Kutta scheme. Baldwin-Lomax model is chosen to describe turbulence. A spatially-varying time-step and an implicit residual smoothing are used to accelerate convergence. A steady mixing approach is used to pass information between stator and rotor blades. For numerical optimization, searching direction is found by the steepest decent and conjugate direction methods, and the golden section method is used to determine optimum moving distance along the searching direction. The object of present optimization is to maximize efficiency. An optimum stacking line is found to design a custom-tailored 3-dimensional blade for maximum efficiency with the other parameters fixed.

• Korean Institute of Interior Design Journal
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• v.17 no.3
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• pp.148-155
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• 2008

The following research focuses on the formation method of digital space by organistic line extension among various digital formation methods. The paper reflects on the meaning and concept of today's digitalism which enables the application of complex organistic system on space through advanced technology. It also explores the concept of a line in topology which differs in assumptive meaning from traditional Euclidian geometry. The findings of the research are that first, digital space is not optimized, but is a tentative formation in process. A digital space encompasses characteristics such as infinity, possibility, potential, asymmetry, and the force of virtuality such characteristics are expressed through a moving surface constantly changing with direction. Second, a digital space formed by line extension is inseparable and durable since no measurement or dimension is predetermined. Furthermore, its sense of direction and flexibility gives it a feeling of a living organism. Third, a Euclidian methodology called 'NURBS' is being developed to express such a dynamic digital space; this is reflected through three elements, control point, weights, and knots to effectively reflect the characteristics of virtuality. The opportunities of digital space are infinite, and the possibilities of formation methods likewise vast.

• The Journal of the Acoustical Society of Korea
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• v.22 no.6
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• pp.489-495
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• 2003

Single towed line array receiver contains an ambiguity on conjugate bearings because of lacking aperture in transverse direction. To solve the left/right bearing ambiguity of line array receiver this paper proposed using single line array with fixed cardioid beam. Fixed cardioid beam has problem about back beam gain exists for steering beam inherent. Back beam is makes form on direction that is different from actually source so that reduced the performance of left/right bearing discrimination. In this paper, line way with adaptive cardioid beam for resolve problem of back beam gain is proposed. So the proposed method has more improved left/right bearing discrimination than fixed cardioid beam, Simulation results show the performance of the proposed method.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.92-96
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• 2010

Deinterlacing methods are usually divided into inter-field deinterlacing and intra-field deinterlacing. The most common method of intra-field deinterlacing is the linear method which uses line doubling or line averaging. There are also some edge-enhancement methods such as ELA(Edge Based Line Average) and modified ELA. However, the linear interpolation generates edge blurring or staircase artifacts. The methods using ELA or modified ELA show poor deinterlacing at various types of edges because of insufficient edge information in a certain direction. This paper presents an intra-field deinterlacing algorithm that considers the interpolation based on edges in 7 directions and an edge line in the horizontal direction. It demonstrates better picture quality by reducing the staircase phenomenon of object in the conventional methods.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.184-184
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• 2011

Using first-principles density-functional calculations, we investigate the chain reaction mechanism of allyl alcohol (ALA) molecules on the H-terminated Si(001)-2${\times}$1 surface. Recently, it was reported [1] that allyl mercaptan (ALM) molecules show a self-directed line growth across the dimer rows through a chain reaction involving several reaction processes: (i) The created radical at the C atom is transferred to the S atom, (ii) the resulting S-centered radical easily abstracts an H atom from the neighboring dimer row, and (iii) the generated S-H group further reacts with the neighboring dimer row to produce the Si-S bond on the neighboring dimer row, accompanying the associative desorption of H2. This H2-desorption process creates a new DB on the neighboring dimer row, setting off the chain reaction across the dimer rows. In the present study, we find that although the structure of ALA with -OH functional is analogous to that of ALM with -SH functional, ALA and ALM lines show a difference in their growth direction. We predict that ALA undergoes the chain reaction to show a line growth along the dimer row, contrasting with the ALM line growth across the Si dimer rows. Our analysis shows that the different growth direction of ALA is due to the strong instability of oxygen radical intermediate, which prevents from growing across the dimer rows. Thus, we demonstrate that the stability of the radical intermediate plays a crucial role in determining the direction of molecular line growth.

• Transactions of Materials Processing
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• v.7 no.1
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• pp.23-35
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• 1998

In order to analyze the tensile deformation characteristics of laser welded tailored blanks. laser welded blanks of different thikness and strength combinations were prepared and tensile tests were done. The tensile elongation along the direction perpendicular to weld line of laser welded blanks was reduced as increasing the deformation restraining force (strength X thicknes) ratio between two welded sheets and fracture occurred at weaker side of base sheets if void ration of welded sheets and fracture occurred at weaker side of base sheets if void ratio of weld section was less than 45% The tensile elongation along weld line reached above 90% of the elongation of base material if welding was done perfectly. Total elongation along the direction perpendicular to weld line was able to be predicted by force equilibrium and power law behavior of base sheets and it was related with the deformation of stronger sheet and formability of weaker side.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.1
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• pp.38-47
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• 1991

The purpose of this study was to investigate the effect of physical properties and grain line of fabrics on the drape properties of the flare skirt. Horizontal section overlap map was obtained by three dimensional Moire Topography, It was concluded drapability of the skirt obtained by the map can be used to determine the ease of the skirt. Grain line such as bias and lengthwise direction showed the difference of quality of the drape at the hem line; skirt made by bias direction showed evenly distributed flare and effective for the aesthetic point view. No difference was observed between cotton and polyester fabrics probably due to the similar characteristics of the fabrics.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.239-254
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• 2006

An efficient descent method for unconstrained optimization problems is line search method in which the step size is required to choose at each iteration after a descent direction is determined. There are many ways to choose the step sizes, such as the exact line search, Armijo line search, Goldstein line search, and Wolfe line search, etc. In this paper we propose a new inexact line search for a general descent method and establish some global convergence properties. This new line search has many advantages comparing with other similar inexact line searches. Moreover, we analyze the global convergence and local convergence rate of some special descent methods with the new line search. Preliminary numerical results show that the new line search is available and efficient in practical computation.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.53.2-53.2
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• 2011

A small number of active galactic nuclei are known to exhibit prominent double peak emission profiles indicating the presence of a relativistic accretion disk model. Using a Monte Carlo technique, we compute the linear polarization of a double peaked broad emission line. A Keplerian accretion disk is adopted for the double peak emission line region and the Schwarzschild geometry is assumed in the emission region. Far from the accretion disk where flat Minkowski geometry is appropriate, we place a scattering region in the shape of a spherical shell sliced. We generate a line photon in the accretion disk in an arbitraray direction in the local rest frame and follow the geodesic of the photon until it hits the scattering region. The profile of the polarized flux is mainly determined by the relative location of the scattering region with respect to the emission source. When the scattering region is in the polar direction, the linear degree of polarization also shows a double peak structure. Under a favorable condition we show that up to 1% of linear degree of polarization may be obtained.