• 한국입자에어로졸학회지
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• 제10권4호
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• pp.177-182
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• 2014

In this study, nickel-coated aluminum (Ni/Al) powders were synthesized for the utilization of energetic applications. Oxide materials present at the surface of Al powders of $45{\mu}m$ in averaged size were removed by using sodium hydroxide(NaOH) solution which is used for controlling pH. Nickel material is coated into the surface of oxide-removed Al powders by electroless-plating process. The microstructure of fabricated Ni/Al powders shows that nickel layers with a few hundreds nm were very homogeneously formed onto the surface of Al powders. The oxidation behavior of Ni/Al exihibit somewhat faster oxidation rate than that of pure Al with surface oxidation. Also, the higher exothermic reaction was observed from the Ni/Al powders. From the result of this, nickel coating is very promising method to obtain highly reactive and safe Al powders for energetic applications.

• Advances in aircraft and spacecraft science
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• 제10권1호
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• pp.83-106
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• 2023

In this work, the static behavior of FGM macro and nano-plates under thermomechanical loading. Equilibrium equations are determined by using virtual work principle and local and non-local theory. The novelty of the current model is using a new displacement field with four variables and a warping function considering the effect of shear. Through this analysis, the considered sandwich FGM macro and nanoplates are a homogeneous core and P-FGM faces, homogeneous faces and an E-FGM core and finally P-FGM faces and an E-FGM core. The analytical solution is obtained by using Navier method. The model is verified with previous published works by other models and very close results are obtained within maximum 1% deviation. The numerical results are performed to present the influence of the various parameters such as, geometric ratios, material index as well as the scale parameters are investigated. The present model can be applicable for sandwich FG plates used in nuclear, aero-space, marine, civil and mechanical applications.

• 한국세라믹학회지
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• 제21권4호
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• pp.327-332
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• 1984

Proper amount of $Al_2O_3$ must be added to increase the yield of mullite which is formed from free silica decomposed from kaolin. The previous study has suggested that Al powder may be a good $Al_2O_3$ supply source at 1400~150$0^{\circ}C$. In this study the application of Al powder is discussed about its mullitization behavior in the higher temperature range of 1500~175$0^{\circ}C$ the results of which compared with those obtained from the reactive $Al_2O_3$ and activated $Al_2O_3$. The oxdation and reaction stages of Al powder were analyzed by DTA crystal growth andmorphology of the mullite were observed by SEM and the yields of the mullite were compared according to their solubilities in HF solution.

• 아동학회지
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• 제23권5호
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• pp.35-50
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• 2002

The present study explored parenting behaviors of fathers associated with 3 types of aggression in their sons and identified inter-generational pathways of aggression. Subjects were 160 Korean elementary school(5-6th grade) boys and their fathers. Data were gathered via questionnaires. Results were that fathers' use of power assertive control and lack of open communication were positively associated with sons' use of both relational and proactive aggression. Fathers' encouragement of aggressive behavior was associated with sons' reactive aggression. Finally, fathers' aggression was net directly associated with sons' aggression, but was fully mediated by parenting. Results were discussed in terms of implications for the Korean cultural context.

• Macromolecular Research
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• 제15권1호
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• pp.17-21
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• 2007

A series of new, vinyl sulfone-containing monomers was prepared by p-aminophenyl vinyl sulfone (1) with various acid chlorides such as adipoly chloride, terephthaloyl chloride and isophthaloyl chloride. Finally, tertiary amine-containing poly(amide-sulfone)s were prepared by the Michael-type addition polymerization using N,N-dimethylethylenediamine (DMEDA), p-phenylenediamine and piperazin. To evaluate the relevant properties for permselective membranes and enzyme substrate, various physical properties such as molecular weight, solubility, quaternization behavior and thermal properties were examined.

• 한국염색가공학회지
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• 제18권5호
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• pp.48-52
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• 2006

A mixed adsorbent prepared by pyrolysing a mixture of carbon and flyash in 1:1 ratio was tested for its deceleration ability for three different classes of dyes, namely Astrazone Blue FRR(C.I. Basic Blue 69), Teflon Blue ANL(C.I. Acid Slue 125) and Verofix Red(Reactive Red 3GL). Equilibrium investigations were carried out at the optimum conditions obtained in the previous studies. The equilibrium data fitted reasonably well to both the Freundlich and Langmuir adsorption models. However the Langmuir model was more appropriate to describe the adsorption behavior of the dyes to the hybrid absorbent system compared with the Freundlich model. The mixed adsorbent cm be an low-cost alternative to activated carbons.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.403-405
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• 1994

The dynamic behavior of circulating current cycloconverter and flywheel energy storage unit is the subject of this investigation. The system of this type can control of real and reactive power flow between flywheel-cycloconverter and power three phase network. In this paper, waveform level simulation indicates that power flow control of is possible and this system can be used to varible application.

• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.1-5
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• 2004

The model of a power system with load dynamics is studied by investigating qualitative changes in its behavior as the reactive power demand at a load bus is increased. The load is created using induction motors parallel with the constant power and constant impedance load. As the load increases, the system experiences various bifurcations such as sub critical and supercritical Hopf, period-doubling and saddle-node bifurcation. The latter may lead the system to voltage collapse. A nonlinear controller is used to control the subcritical Hopf bifurcation and hence mitigate voltage collapse. It is applied to the KEPCO (Korean Electric Power Company) system to demonstrate its validity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.289-291
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• 2000

In a competitive electricity power market, the price of electricity changes instantly, that of conventional market is predetermined and hardly changes. In such a new environment, customers' behaviors change instantly according to the changing electricity prices. If we develop a electricity load model that well describes the behavior of electricity consumers, we can utilize that model in forecasting the amount of future load, solving the load flow problem and finding the weak point of the system. In this paper new electricity model that considers the price of electricity and power factor of the load is presented. While conventional load model, which is demand function of electricity, uses the price of real and reactive power as the independent variable of the demand function. this new load model uses price of real power and penalty factor according to the power factor for the calculation of amount of electricity demand.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.519-524
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• 2005

A numerical process to simulate SiO2 dry etching with inductively coupled C2F6 plasmas has been constructed using a commercial CFD code as a first step to design a run-to-run control system. The simulator was tuned to reasonably predict the reactive ion etching behavior and used to investigate the effects of plasma operating variables on the etch rate and uniformity. The relationship between the operating variables and the etching characteristics was mathematically modeled through linear regression for future run-to-run control system design.