• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.237-238
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• 2007

A new strain analysis model, so called the stress matched model, in an epitaxial multilayer system is proposed. The model makes it possible to know the strain, the stress, the elastic strain energy in each epitaxial layer. Analytical formulas of strain parameters in each epitaxial layer are derived under assumptions that the substrate thickness is finite and the in-plane lattice constant is the same for all epitaxial layers for dislocation free growth. As an example, the model is applied to a 405nm InGaN/InGaN multiple quantum well laser diode. Analysis result shows that AlxGa1-xN layer with Al mole fraction of 0.06 and the thickness of 6${\mu}m$ is one of good templates for a laser. In fact, this layer structure coincides with experimentally optimized one.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.104-109
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• 2000

The modes of oscillation and radiated acoustic fields of compressible flows over open cavities are investigated computationally. The compressible Navier-Stokes equations are solved for two-dimensional cavities with laminar boundary layers upstream. The high-order and high-resolution numerical schemes are used for the evaluation of spatial derivatives and the time integration. Physically correct numerical boundary conditions are implemented to produce time-accurate solutions in the whole computation domain. The computational domain is large enough to directly resolve a portion of the radiated acoutic field. The results show a transition from a shear layer mode, for shorter cavities and lower Mach numbers, to a wake mode for longer cavities and higher Mach numbers. The shear layer mode is well characterized by Rossiter modes and these oscillations lead to intense upstream acoustic radiation dominated by a single frequency. The wake mode is characterized instead by a large-scale vortex shedding. Acoustic radiation is more intense, with multiple frequencies present.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.491-493
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• 2000

A case of a botryoid odontogenic cyst of the globulomaxillary area between the right upper lateral incisor and the canine presenting as an apical periodontal cyst was reported. The cyst showed an unilocular radiolucency with a well delineated hyperostotic border. Histologic examination revealed multiple cysts lined by one or two-cell layers, some areas demonstrated a bud-like thickening of the epithelium. Clear cells were also conspicuous, but devoid of inflammatory reaction in the cystic wall. Some considerations regarding differential diagnosis, histogenetic and biologic behaviour of the lesion were discussed.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.44-48
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• 2013

Artificial neural network (ANN) model is applied to predict arc welding process window for automotive steel plate. Target weldment was various automotive steel plate combination with lap fillet joint. The accuracy of prediction was evaluated through comparison experimental result to ANN simulation. The effect of ANN variables on the accuracy is investigated such as number of hidden layers, perceptrons and transfer function type. A static back propagation model is established and tested. The result shows comparatively accurate predictability of the suggested ANN model. However, it restricts to use nonlinear transfer function instead of linear type and suggests only one single hidden layer rather than multiple ones to get better accuracy. In addition to this, obvious fact is affirmed again that the more perceptrons guarantee the better accuracy under the precondition that there are enough experimental database to train the neural network.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.808-810
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• 2005

Inexpensive large area arrays of thin film transistors (TFTs) on flexible substrates will enable many new display products that cannot be cost effectively manufactured by conventional means. This paper presents a new approach for low cost manufacturing of electronic devices using roll-to-roll (R2R) processes exclusively. It was developed in partnership by Hewlett Packard Laboratories and Iowa Thin Film Technologies (ITFT), a solar cell manufacturer. The approach combines ITFT's unique processes for vacuum deposition and etching of semiconductors, dielectrics and metals on continuous plastic webs with a method HP has invented for the patterning and aligning the multiple layers of a TFT with sub-micron accuracy and feature size.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.100-107
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• 2011

Algorithms based on the QR decomposition of the equivalent space-time channel matrix have been proved useful in the detection of V-BLAST systems. Especially, the parallel detection (PD) algorithm offers ML approaching performance up to 4 transmit antennas with reasonable complexity. We show that when directly applied to STBCs, the PD algorithm may suffer a rather significant SNR degradation over ML detection, especially at high SNRs. However, simply extending the PD algorithm to allow p ${\geq}$ 2 candidate layers, i.e. p-PD, regains almost all the loss but only at a significant increase in complexity. Here, we propose a simplification to the p-PD algorithm specific to STBCs without a corresponding sacrifice in performance. The proposed algorithm results in significant complexity reductions for moderate to high order modulations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.4
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• pp.390-396
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• 2010

Resonant frequencies and the associated vibrational modes of multiwall carbon nanotubes are studied in this paper. The analysis is based on a multiple-elastic beam model, considering intertube radial displacements and the related internal degrees of freedom. Especially, van der Waals interaction is modified considering both all interaction between each layers in multi-wall carbon nanotubes and curvature effect. The results show that modified van der Waals interaction could significantly affect the natural frequencies of multi-walled carbon nanotubes. In particular, non-coaxial intertube resonance will be excited at the higher resonant frequencies of multiwall carbon nanotubes.

• Geomechanics and Engineering
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• v.9 no.2
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• pp.169-193
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• 2015

This paper is the second part of the study for determining the seismic behavior of soil systems. The aim of this part is to present solution approaches for determining seismic site amplification. For this purpose, two solution techniques are used. The first technique is equivalent linear analysis which is mostly used in literature. The other technique is real time parameter updating approach and this approach uses the possibilities of Simulink effectively. A graphical user interfaced (GUI) program called DTASSA standing for Discrete-Time Analysis of Seismic Site Amplification is developed. In DTASSA, automatic block diagram producing system is developed and seismic site amplification for multiple soil layers may easily be investigated in real time. Numerical applications have been carried out to check the reliability of developed algorithm. The results of DTASSA are compared with SUA, EERA and NERA programs for the particular example problems.

• Geomechanics and Engineering
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• v.9 no.2
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• pp.145-167
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• 2015

Digital simulation has recently become the preferred method for designing complex and dynamic systems. Simulation packages provide interactive, block-diagram environment for modeling and simulating dynamic models. The block diagrams in simulation models are flowcharts which describe the components of dynamic systems and their interaction. This paper is the first part of the study for determining the seismic behavior of soil systems. The aim of this part is to present the constructed block diagrams for discrete-time analysis of seismic site amplification in layered media for vertically propagating shear waves. Detailed block diagrams are constructed for single and multiple soil layers by considering wave propagation with and without damping, respectively. The block diagrams for recursive filter to model attenuation in discrete-time form are also constructed. Finite difference method is used for strain calculation. The block diagrams are developed by utilizing Simulink which is a software add-on to Matlab.

• Journal of Powder Materials
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• v.25 no.1
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• pp.60-68
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• 2018

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.