• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.54.2-54.2
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• 2012

Solid-state dewetting of thin films is a process through which continuous solid films decay to form islands. Dewetting of thin films has long been a critical issue in microelectronics and much effort has been made to prevent the process and enhance the stability of films. On the other hand, dewetting has also been purposely induced to create arrays of particles and other structures for applications, including plasmonic structures and catalysts for growing nanotube and nanowire. We have investigated ways of producing regular structures via templated dewetting of thin films. Mainly, two different approaches have been used in our works to template dewetting of thin films: periodic topographical templating and planar patterning of epitaxially-grown films. Dewetting of topographically-patterned thin films results in the formation of nanoparticle arrays with spatial and crystallographic orders. Morphological evolution during templated-dewetting of single crystal films occurs in deterministic ways because of geometric and crystallographic constraints, and leads to the formation of regular structures with smaller sizes and more complex shapes than the initial patches. These results will be reviewed in this presentation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.3
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• pp.114-121
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• 2003

Through comparing stress state of TEOS and SiLK-embedded structures, the effect of low-k materials on stress and stress distribution in via-line structures were investigated using three-dimensional finite element analyses. In the case of TEOS-embedded via-line structures, hydrostatic stress was concentrated at the via and the top of the lines, where the void was suspected to nucleate. On the other hand, in the via-line structures integrated with SiLK, large von-Mises stress is maintained at the via, thus deformation of via is expected as the main failure mode. A good correlation between the calculated results and experimentally observed failure modes according to dielectric materials was obtained.

• Steel and Composite Structures
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• v.35 no.3
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• pp.405-413
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• 2020

Current study on the buckling analysis of steel plate in composite structures normally focuses on applying finite element method to derive the buckling stress. However, it is time consuming, computationally complicated and tedious for general use in design by civil engineers. Therefore, in this study an analytical study is conducted to predict the buckling behavior of steel plates in composite structures. Hand calculation method was proposed based on energy principle. Novel buckling shapes with biquadratic functions along both loaded and unloaded direction were proposed to satisfy the boundary condition. Explicit solutions for predicting the critical local buckling stress of steel plate is obtained based on the Rayleigh-Ritz approach. The obtained results are compared with both experimental and numerical data. Good agreement has been achieved. Furthermore, the influences of key factors such as aspect ratio, width to thickness ratio, and elastic restraint stiffness on the local buckling performance are comprehensively discussed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.97-118
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• 2019

Based on Nonlinear Finite Element Analysis (NFEA), this paper focuses on the bi-axial ultimate strength of typical bottom structures under corrosion. On one hand, uniform and not simultaneous corrosion across different structures is introduced, and surrogate models by Gaussian Process (GP) are built for both longitudinal and transverse cases individually, and corresponding probabilistic characteristics are investigated; meanwhile, corrosion effects on interaction between bi-axial stresses at ultimate state are studied. On the other hand, non-uniform localized pitting corrosion of normally distributed circular shapes is introduced, and different pitting corrosion densities are considered; structural bi-axial ultimate strengths under pitting corrosion are studied, and the results are compared with that from equivalent uniform corrosion; the probabilistic characteristics of structural ultimate strength in life cycle are studied; finally, the ultimate strength under randomly distributed pitting corrosion is compared with results from normally distributed pitting and uniform corrosion under various boundary conditions.

• Archives of Reconstructive Microsurgery
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• v.13 no.2
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• pp.107-116
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• 2004

Flaps are necessary, when important structures such as bone, tendon, nerve and vessel are exposed. Arterialized venous free flap is suited to the coverage of finger and hand because the thickness of venous flap is thin. Authors performed 65 cases arterialized venous free flap for the soft tissue reconstruction of the hand and finger. The size of donor defect were from $1{\times}1cm\;to\;7{\times}12cm$. The mean flap area was $9.1cm^2$. The recipient sites were finger tip in 34 cases, finger shaft in 29 cases and hand in 2 cases. The donor sites were volar aspect of distal forearm in 40 cases, thenar area in 17 cases and foot dorsum in 6 cases. The types of arterialized venous free flap were A-A type in 4 cases and A-V type in 61 cases. The length of afferent vein was from 0.5 cm to 3 cm (mean 1.7 cm) and efferent vein was from 1 cm to 10 cm (mean 2.2 cm). 58 flaps(89.2%) survived eventually. 42 flaps(64.6%) survived totally without any complication. 8 flaps(12.3%) showed the partial necrosis but they were healed without any additional operations. 8 flaps (12.3%) showed the partial necrosis requiring the additional skin graft. We had a satisfactory result by using arterialized venous free flap for the soft tissue reconstruction of finger and hand. We believe that volar aspect of distal forearm, thenar area, foot dorsum are suited as a donor site and the short length of the flap pedicle, the strong arterail inflow affect the survival rate of arterialized venous free flaps.

• Archives of Plastic Surgery
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• v.35 no.1
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• pp.67-72
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• 2008

Purpose: The hand is frequently affected area in high voltage electrical burn injury as an input or output sites. Electrical burn affecting the hand may produce full thickness necrosis of the skin and damage deep structures beneath the eschar, affecting the tendon, nerve, vessel, even bone which result in serious dysfunction of the hand. As promising methods for the reconstruction of the hand defects in electrical burn patients, we have used the peroneal perforator free flaps. Methods: From March 2005 to June 2006, we applied peroneal perforator free flap to five patients with high tension electrical burn in the hand. Vascular pedicle ranged from 4cm to 5cm and flap size was from $4{\times}2.5cm$ to $7{\times}4cm$. Donor site was closed primarily.Results: All flaps survived completely. There was no need to sacrifice any main artery in the lower leg, and there was minimal morbidity at donor site. During the follow-ups, we got satisfactory results both in hand function and in aesthetic aspects.Conclusion: The peroneal perforator flap is a very thin, pliable flap with minimal donor site morbidity and is suitable for the reconstruction of small and medium sized wound defect, especially hand with electrical burn injury.

• Earthquakes and Structures
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• v.7 no.6
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• pp.895-908
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• 2014

The main objective of critical excitation methods is to reveal the worst possible response of structures. This goal is accomplished by considering the uncertainties of ground motion, which is subjected to the appropriate constraints, such as earthquake power and intensity limit. The concentration of this current study is on the theoretical optimization aspect, as is the case with the majority of conventional critical excitation methods. However, these previous studies on critical excitation lead to a discontinuous power spectral density (PSD). This paper introduces some critical excitations which contain proper continuity in frequency domain. The main idea for generating such continuous excitations stems from the combination of two continuous functions. On the other hand, in order to provide a non-stationary model, this paper attempts to present an appropriate envelope function, which unlike the previous envelope functions, can properly cover the natural earthquakes' accelerograms based on multi-peak conditions. Finally, the proposed method is developed into the multiple-degree-of-freedom (M.D.O.F) structures.

• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.5
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• pp.31-39
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• 2018

Recently, there has been active studies to provide a user-friendly interface in a virtual reality environment by recognizing user hand gestures based on deep learning. However, most studies use separate sensors to obtain hand information or go through pre-process for efficient learning. It also fails to take into account changes in the external environment, such as changes in lighting or some of its hands being obscured. This paper proposes a hand gesture recognition method based on deep learning that is strong in external environments without the need for pre-process of RGB images obtained from general webcam. In this paper we improve the VGGNet and the GoogLeNet structures and compared the performance of each structure. The VGGNet and the GoogLeNet structures presented in this paper showed a recognition rate of 93.88% and 93.75%, respectively, based on data containing dim, partially obscured, or partially out-of-sight hand images. In terms of memory and speed, the GoogLeNet used about 3 times less memory than the VGGNet, and its processing speed was 10 times better. The results of this paper can be processed in real-time and used as a hand gesture interface in various areas such as games, education, and medical services in a virtual reality environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.328-334
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• 1996

Finite Element Method(FEM) is the most popularly used method in analyzing the dynamic behaviors of structures. But unless the number of finite elements is large enough, the results from FEM are somewhat different from exact analytical solutions, especially at high frequency range. On the other hand, as the Spectral Element Method(SEM) deals directly with the governing equations of structures, the results from this method cannot but be exact regardless of any frequency range. However, despite two dimensional structures are more general, the SEM has been applied only to the analysis of one dimensional structures so far. In this paper, therefore, new methodologies are introduced to analyze the two dimensional plate using SEM. The results from this new method are compared with the exact analytical solutions by letting the two dimensional plate be one dimensional one and showed the dynamic responses of two dimensional plate by including various waves propagated into x-direction.

• Journal of KSNVE
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• v.6 no.5
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• pp.617-624
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• 1996

Finite Element Method(FEM) is one of the most popularly used method in analyzing the dynamic behaviors of structures. But unless the number of finite elements is large enough, the results from FEM are somewhat different form exact analytical solutions, especially at high frequency range. On the other hand, as the Spectral Element Method(SEM) deals directly with the governing equations of structures, the results from this method cannot but be exact regardless of any frequency range. However, despite two dimensional structures are more general, the SEM has been applied only to the analysis of one dimensional structures so far. In this paper, therefore, new methodologies are introduced to analyze the two dimensional plate structure using SEM. The results from this new method are compared with the exact analytical solutions by letting the two dimensional plate structure be one dimensional and showed the dynamic responses of two dimensional plate by including various waves propagated into x-direction.