• Journal of the Korea Furniture Society
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• v.19 no.5
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• pp.403-410
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• 2008

This study is a background for developed woodworking educational program. To achieve the propose of this research, related to handwork to figure out the concept, changes and characteristics of handwork and the products of handwork. The areas of woodworking needs basic hand function of gripping and hooking, strong hands and stability of hand operation. Activities of this area can enhance the ability of controlling the strength of hand and the stability of hand operation. The use of both hands in woodworking promotes the coordination of both hands and handling ability. In the woodworking, diverse functions of hands are used with various tools. Each hand may be move differently, and the hand operation is elaborated. These features of woodworking help growing coordinations and hand function, and developing brain and creativeness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.811-815
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• 2005

We theoretically studied synchronization of chaotic oscillation in semiconductor lasers with chaotic light injection feed-back induced chaotic light generated from a master semiconductor laser was injected into a solitary slave semiconductor laser. The slave laser subsequently exhibited synchronized chaotic output for a wide parameter range with strong injection and frequency detuning within the injection locking scheme. We also analytically examined chaos synchronization based on a linear stability analysis from the view point of synchronization based on a linear stability analysis from the view point of modulation response of injection locked semiconductor lasers to chaotic light signal.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.480.2-480.2
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• 2014

Electrochemical capacitors have been the most strong energy storage devices due to high power density and long cycle stability. Pristine carbon nanotubes are promising electrode materials for excellent electrical conductivity and high specific surface area in electrochemical capacitor. However, the practical application of pristine carbon nanotubes was limited by the aggregation into bundles due to van der Waals force. In this research, we explained how multi-walled carbon nanotubes (MWCNT) functionalized by carboxyl, sulfonic, and amine groups (CNT-COOH, CNT-SO3H, CNT-NH2) to improve the performances of MWCNT. Functionalized CNTs showed two- to four-fold increase in capacitance over that of pristine CNTs, while maintaining reasonable cyclic stability. But, the CNT-COOH showed the lowest rate capability of 57% compared to 84%, 86% of CNT-SO3H and CNT-NH2. As demonstrated by the spectroscopic analysis, This reseach showed how surface functional group of carbon nanotubes change capacitor performances.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.206-213
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• 2016

Transition metal oxide-based electrodes for lithium ion batteries have recently attracted much attention because of their high theoretical capacity. Here we report the electrochemical behavior of cobalt oxide nanorods as anodes, prepared by a template-free, one-step electrochemical deposition of cobalt nanorods, followed by an oxidation process. The as-deposited cobalt has a slightly convex columnar structure, and controlled thermal oxidation produces cobalt oxides of different Co/O ratios, while the original shape is largely preserved. As an anode in a rechargeable lithium battery, the Co/O ratio has a strong effect on initial capacity and cycling stability. In particular, the one-dimensional Co@Co_xO_y core shell structure obtained from a mild heat-treatment results in superior cycling stability.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.705-710
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• 1999

Stability and chemical durability for aqueous casting of BaTiO3 slurry with polycarylic acid(PAA) were studied. PAA was well chemisorbed on surface of BaTiO3 powder at neutral pH but did not chemically adsorbed at low pH. The amount of Ba dissolution in aqueous BaTiO3 slurry was abruptly increased at strong acid pH2 and also at high amount of PAA. Protection of Ba dissolution and stability of slurry could be obtained through the optimization of slurry conditions such as pH amount of surfactant and solid content.

• Macromolecular Research
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• v.14 no.1
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• pp.107-113
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• 2006

Processible norbornene copolymers were realized by judiciously designing norbomene comonomers, which were themselves prepared by the Diels-Alder reaction of cyclopentadiene and benzoquinone followed by the isomerization and alkylation of alcohols. The norbornene copolymers containing these derivatized comonomers, prepared by [Pd($x_{2}CH-{3} $)$_{4}$][$SbF_{6}$]$_{2}$ catalyst, exhibited excellent solubility in many organic solvents as well as good thermal stability, as evidenced by their high glass transition ($T_{g}$) and decomposition ($\∼$350$^{circ}C$) temperatures. In addition, fairly strong adhesion to substrates such as glasses and silicon wafers was also achieved with these copolymers to overcome the limitations experienced by polynorbornene homopolymers and to make them attractive for many important industrial applications.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.866-867
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• 2006

This work will report a highly textured ${\beta}-Si_3N_4$ ceramic by aqueous slip casting in a magnetic field and subsequent pressureless sintering, Effects of the sintering aids, polymer dispersant, pH and stirring time on the stability of the $Si_3N_4$ slurries were studied. The textured ${\beta}-Si_3N_4$ with 97 % relative density could be obtained by slip casting in a magnetic field of 12 T and subsequent sintering at $1800^{\circ}C$ for 1 h. The textured microstructure is featured by the alignment of c-axis of ${\beta}-Si_3N_4$ crystals perpendicular to the magnetic field, and the Lotgering orientation factor, f, is determined to be 0.8.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.790-791
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• 2006

The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the ($10\bar{1}1$) plane. The fracture mechanism of $Nd_2Fe_{14}B$ magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of $Nd_2Fe_{14}B$ magnets were also reported.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.4
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• pp.320-329
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• 2016

An implicit method of solving the six degree-of-freedom rigid body motion equations based on the second order Adams-Bashforth-Moulten method was utilised as an improvement over the leapfrog scheme by making modifications to the rigid body motion solver libraries directly. The implementation will depend on predictor-corrector steps still residing within the hybrid Pressure Implicit with Splitting of Operators - Semi-Implicit Method for Pressure Linked Equations (PIMPLE) outer corrector loops to ensure strong coupling between fluid and motion. Aitken's under-relaxation is also introduced in this study to optimise the convergence rate and stability of the coupled solver. The resulting coupled solver ran on a free floating object tutorial test case when converged matches the original solver. It further allows a varying 70%-80% reduction in simulation times compared using a fixed under-relaxation to achieve the required stability.

• Journal of Power Electronics
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• v.14 no.3
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• pp.549-563
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• 2014

In this paper, the speed regulation problem of permanent synchronous motor (PMSM) systems under the vector control framework is studied. A model reference adaptive controller (MRAC) based on the Lyapunov stability theory is first designed. Since the standard MRAC method provides poor disturbance rejection performance in the case of strong disturbances, a composite control method which combines the MRAC method and the disturbance estimation method, called the MRAC+ESO method, is proposed. An extended state observer (ESO) is introduced to estimate the lumped disturbances. The obtained estimated value acts as a feedforward compensation term to the MRAC controller. A stability analysis of the composite control method is given. Simulation and experimental results are presented and compared to show the effectiveness of the proposed control method.