• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.95.3-95
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• 2001

This paper investigates the simultaneous use of mixed H2/H_inf and mu-synthesis design methodology to design a robust controller for flexible link. We adopt four steps to design control system as follows: Step 1 : Generally, there are differences between the nominal and real model, so we consider the plant as a combination of parametric model uncertainty and unstructured uncertainty represents real structural uncertainties associated with the damping ratios of the flexible modes retained in the nominal model without payload. denotes the uncertainty which is due to the payload added at the tip. Step 2 : We adopt the mixed H2/H_inf theory to design a feedback controller K(s) by using the model uncertainty ...

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.979-985
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• 1993

Diamond films were synthesized using CH4-H2-Ar mixture gases by MWCVD, and cutting ability was tested after brazing them onto WC tools. Growth rates were in the range of 0.5~10${\mu}{\textrm}{m}$/hr depending on the deposition conditions, and diamond films with thickness of 100~300${\mu}{\textrm}{m}$ were obtained. Diamond tools brazed by RF induction method showed an enhanced cutting ability in the cutting test of Si single crystal rod.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.30-31
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• 2006

The LSCF cathode for Solid Oxide Fuel Cell was investigated to develop high performance unit cell at intermediate temperature by modified oxalate method with different electrolyte. The LSCF precursors using oxalic acid, ethanol and $NH_4OH$ solution were prepared at $80^{\circ}C$, and pH was controlled as 2, 6, 7, 8, 9 and 10. The synthesis precursor powders were calcined at $800^{\circ}C$, $1000^{\circ}C$ and $1200^{\circ}C$ for 4hrs. Unit cells were prepared with the calcined LSCF cathode, buffer layer between cathode and each electrolyte that is the LSGM, YSZ, ScSZ and CeSZ. The synthesis LSCF powders by modified oxalate method were measured by scanning electron microscope and X-ray diffraction. The interfacial polarization resistance of cell was characterized by Solatron 1260 analyzer. The crystal of LSCF powders show single phase at pH 2, 6, 7, 8 and 9, and the average particle size was about $3{\mu}m$. The electric conductivity of synthesis LSCF cathode which was calcined at $1200^{\circ}C$ shows the highest value at pH 7. The cell consist of GDC had the lowest interfacial resistance (about 950 S/cm@650) of the cathode electrode. The polarization resistance of synthesis LSCF cathode by modified oxalate method has the value from 4.02 to 7.46ohm at $650^{\circ}C$. GDC among the electrolytes, shows the lowest polarization resistance.

• Journal of Powder Materials
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• v.25 no.5
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• pp.420-425
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• 2018

Core-shell structured nanoparticles are garnering attention because these nanoparticles are expected to have a wide range of applications. The objective of the present study is to improve the coating efficiency of gold shell formed on the surface of silica nanoparticles for $SiO_2@Au$ core-shell structure. For the efficient coating of gold shell, we attempt an in-situ synthesis method such that the nuclei of the gold nanoparticles are generated and grown on the surface of silica nanoparticles. This method can effectively form a gold shell as compared to the conventional method of attaching gold nanoparticles to silica particles. It is considered possible to form a dense gold shell because the problems caused by electrostatic repulsion between the gold nanoparticles in the conventional method are eliminated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2004.05a
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• pp.50-50
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• 2004

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.405-408
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• 1998

Generally, the principle function of simulator control loading system is to provide the pilot or student with the "feel" of the actual aircraft flight control systems during flight, taxing, and in malfunction. Flight control "feel" is the resistance felt by the pilot when moving a control stick or pedal, coupled with the amount of control surface deflection, and hence aircraft response, resulting from the input. Therefore, the control loading servo must be capable of performing to some general list of requirements derived from real aircraft control forces. In this paper, we deal with a $\mu-controller$ design for a control loading system of the flight simulator. For this, we derive a frequency response of the hydraulic system from the identification data and then design a controller using a $\mu-synthesis$ method. Under the same condition of simulation, $\mu-controller$ provides the superior performance than PID controller.than PID controller.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.28 no.1
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• pp.11-22
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• 2015

Objective : Siegesbeckia Herba can treat various skin disease by expelling wind and removing dampness and clearing away heat and toxic material effects. This study was designed to investigate effects of Siegesbeckia Herba Extracts(SHE) on skin elasticity and whitening using B16F10 cell lines. Method : In this experiment, We observed effect of SHE on cell viability, inhibition of melanin synthesis and inhibitory effect on tyrosinase and elastase. Results : 1. SHE treated group showed decreased cell viability rates significantly compared with non-treated group. More than SHE $250{\mu}g/ml$, $500{\mu}g/ml$ and $1,000{\mu}g/ml$ of treated groups were lower levels of melanin synthesis respectively. 2. SHE significantly showed tyrosinase inhibitory activity in vitro, SHE increased tyrosinase inhibitory activity and elastase inhibitory activity in B16F10 cells, and tyrosinase inhibitory activity in vitro. 3. Tyrosinase inhibitory activity and elastase inhibitory activity in B16F10 cells, tyrosinase inhibitory activity in vitro were not accepted statistical significance compared with non-treated group. 4. SHE treated group showed increased SOD-like activity rates significantly compared with non-treated group. More than SHE $250{\mu}g/ml$, $500{\mu}g/ml$ and $1,000{\mu}g/ml$ of treated groups were lower levels of melanin synthesis respectively. Conclusion : These results suggest that SHE can inhibit melanin synthesis and tyrosinase inhibtory activity. So, We suggest that SHE can be maintained skin whitening.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.185-189
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• 2001

Amorphous aluminium phosphate powders were synthesized as a single phase by neutralization reaction of a stoichiometric mixture of $Al_2(SO_4)_3$ and $H_3PO_4$ using the NaOH or KOH solution and subsequently by the hydrothermal precipitation method. The synthesis conditions were as follows : starting materials; $Al_2(SO_4)_3$ and $H_3PO_4$,pH ranges of neutralization reaction; between 5.6 and 6.0, temperature ranges of hydrothermal reaction; between 170 and $180^{\circ}C$,time ranges of hydrothermal reaction; between 4 and 5hs. Under such synthesis conditions, the products are obtained as amorphous aluminium phosphate powders of 0.1~0.3$\mu\textrm{m}$ in size and are Eitted to USP (United Standard Pharmacopoeia) test.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.400-405
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• 1997

Lead scandium niobate powders were prepared by a molten salt synthesis method using KCl as a flux. Variations in phase formation and particle morphology were investigated for the temperature range $700^{\circ}C$ to $850^{\circ}C$. Pure $Pb(Sc_{1/2}Nb_{1/2})O_3$ perovskite phase was formed at $850^{\circ}C$ after 2hrs and the average particle size of powder was below 0.5 $\mu\textrm{m}$. The results are discussed with respect to DTA, X-ray diffraction, and microstructural characterization data.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.295-298
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• 2009

Oxygen ionic conductors of CeScSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have the triple-phase-boundaries of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of CeScSZ electrolyte powder. In this report, nanoscale CeScSZ electrolyte powder was synthesized by chemical synthesis method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting using the synthesized CeScSZ electrolyte powder, and ionic conductivity and gas permeability of electrolyte film were evaluated. Finally the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering, in which the active layer, measuring $20{\mu}m$, was introduced in the anode layer to provide a more efficient reaction. Electrochemical evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.