• Applied Microscopy
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• v.25 no.2
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• pp.73-79
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• 1995

The oxidation of silicon wafers is an essential step in the fabrication of semiconductor devices. It is known to induce degradation of electrical properties and lattice strain of Si substrate from thermal oxidation process due to charged interface and thermal expansion mismatch from thermally grown SiO, film. In this study, convergent beam electron diffraction technique is employed to directly measure the lattice strains in Si(100) and $4^{\circ}$ - off Si(100) substrates with thermally grown oxide layer at $1200^{\circ}C$ for three hours. The ratios of {773}-{973}/{773}-{953} Higher Order Laue Zone lines were used at [012] zone axis orientation. Lattice parameters of the Si substrate as a function of distance from the interface were determined from the computer simulation of diffraction patterns. Correction value for the accelerating voltage was 0.2kV for the kinematic simulation of the [012]. HOLZ patterns. The change in the lattice strain profile before and after removal of oxide films revealed the magnitudes of intrinsic strain and thermal strain components. It was shown that $4^{\circ}$ -off Si(100) had much lower intrinsic strain as surface steps provide effective sinks for the free Si atoms produced during thermal oxidation. Thermal strain in the Si substrate was in compression very close to the interface and high concentration of Si interstitials appeared to modify the thermal expansion coefficient of Si.

• Applied Microscopy
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• v.24 no.4
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• pp.115-122
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• 1994

A computer program has been developed to analyze easily the Kikuchi pattern which is useful in obtaining the crystallographic data of materials. This program can simulate the Kikuchi patterns for 14 Bravais lattice by using the matrix algebra. Convenient menu system was also added to enhance the applications of the program. That is, by varying the tilting angle, camera length (RADIUS) and $S_{max}$ in the menu, various Kikuchi patterns can be obtained. The simulated patterns, then, can be compared with the experimentally-obtained Kikuchi pattern to examine validity of simulation.

• Applied Microscopy
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• v.21 no.1
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• pp.108-120
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• 1991

Principles of electron diffraction patterns in transmission electron microscope are described for beginners in terms of reciprocal lattices and Ewald sphere. Analysis of both ring patterns and spot patterns are illustrated with practical examples as well as basic calibrations of TEM. Especially convergent beam electron diffraction method is emphasized for the determination of lattice parameters, microstrains, and thickness of thin foil followed by a review of microcomputer programs for the electron diffraction analyses explained in this paper.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.662-667
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• 2007

A new neuro-control scheme for active control of structures is proposed. It utilizes lattice pattern of state vector as training data of probabilistic neural network(PNN). Therefore. it is the so-called lattice probabilistic neural network(LPNN). PNN makes control forces by using all the training patterns. Therefore, it takes much time to obtain a control force in application. This inevitably may delay the control action. However. control force of LPNN is calculated by using only the adjacent information of LPNN input. So, the response of LPNN is greatly faster than PNN. The proposed control algorithm is applied for three story building under California and El Centro earthquakes. Also, control results of the LPNN are compared with those of the conventional PNN. The structural responses have been suppressed effectively by the proposed algorithm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.846-850
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• 2005

[ $SrTiO_3$ ]:Al, Pr red phosphors for FED were synthesized by solid state reaction method. The dependence of their luminescent properties on Sr and Al concentration was investigated. The $SrTiO_3$: Al, Pr phosphors showed the characteristic X-ray diffraction patterns of the perovskite structure. Photoluminescence intensity and lattice constant in $SrTiO_3$: Al, Pr phosphors changed in quite a similar manner with Sr concentration. Photoluminescence intensity increased with increasing lattice constant, and the decrease of photoluminescence intensity and lattice constant occurred in the vicinity of 1 mol Sr concentration.

• Transactions of Materials Processing
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• v.32 no.5
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• pp.255-267
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• 2023

Recently, 3D printing using a material extrusion method is used in various fields. Since plastic material has lower strength than steel, research to increase the strength is continuously being conducted. This study investigates the lattice structure for additive manufacturing of six 3D infill patterns (octet, quarter cubic, cubic, cubic subdivision, triangles and cross 3D) which consist of tetragons, hexagonal trusses, equilateral triangles and cross shapes. Consequently, in the tensile strength considering the weight and printing time, octet, quarter cubic, cubic and triangles patterns tended to increase linearly as the infill density increased, except for the infill density of 20%. However, the tensile strength/weight performed better than the infill density of 100% when the cubic subdivision pattern had the infill density of 20% and the cross 3D pattern had the infill density of 40%. Considering the weight and printing time, the infill patterns of high tensile strength were octet, quarter cubic, cubic, cubic subdivision, triangles and cross 3D order.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.42.6-42
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• 2002

Kohonen's self organizing feature map (SOFM) converts arbitrary dimensional patterns into one or two dimensional arrays of nodes. Among the many competitive learning algorithms, SOFM proposed by Kohonen is considered to be powerful in the sense that it not only clusters the input pattern adaptively but also organize the output node topologically. SOFM is usually used for a preprocessor or cluster. It can perform dimensional reduction of input patterns and obtain a topology-preserving map that preserves neighborhood relations of the input patterns. The traditional SOFM algorithm[1] is a competitive learning neural network that maps inputs to discrete points that are called nodes on a lattice...

• Journal of Magnetics
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• v.13 no.2
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• pp.61-64
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• 2008

We studied the effect of the variation of the lattice constant on the electrical properties of $SrRuO_3$ thin films. In order to obtain films with different volumes, we varied the substrate temperature and oxygen pressure during the growth of the films on $SrTiO_3$ (001) substrates. The films were grown using a pulsed laser deposition method. The X-ray diffraction patterns of the grown films at low temperature and low oxygen pressure indicated the elongation of the c-axis lattice constant compared to that of the films grown at a higher temperature and higher oxygen pressure. The in-plane strain states are maintained for all of the films, implying the expansion of the unit-cell volume by the oxygen vacancies. The variation of the electrical resistance reflects the temperature dependence of the resistivity of the metal, with a ferromagnetic transition temperature inferred form the cusp of the curve being observed in the range from 110 K to 150 K. As the c-axis lattice constant decreases, the transition temperature linearly increases.

• Structural Engineering and Mechanics
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• v.21 no.6
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• pp.677-698
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• 2005

In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.326-333
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• 2005

Many XML applications use XPath Patterns as a query language for XML documents. Two XPath patterns may have containment relationship, and the containment problem between two XPath patterns is a problem that determines whether one XPath pattern contains another XPath Pattern. Although the containment problem occurs in many applications, it is known as a co-NP complete. A homomorphism problem, which is a sufficient condition for the containment problem, is solved in polynomial time. We first discuss applications that replace the containment problem with the homomorphism problem, and maintaining homomorphism information among XPath patterns will benefit those applications. Then, we propose a lattice structure, called POX (Partially Ordered Set of XPath Patterns), and develop algorithms for maintaining it. As our analyses show, the algorithms can efficiently maintain POX in polynomial time.