• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.755-757
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• 1998

The thermally stimulated current (TSC) of PVDF thin film prepared by physical vapor deposition method was investigated. PVDF shows three TSC peaks designated $P_1$, $P_2$ and $P_3$ in ascending order of temperature. The $P_1$ peak is associated with water in the PVDF specimen. $P_2$ and $P_3$ Peaks are specific peaks of $\alpha$ and $\beta$ type PVDF, respectively. The peak temperature was shifted to higher temperature, and peak intensity was decreased with increasing substrate temperature under thin film preparation.

• International Journal of Contents
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• v.15 no.4
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• pp.27-35
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• 2019

In this paper, we propose an advanced Minimum Mean Square Error (MMSE) channel estimation method for IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) systems. To improve the performance of MMSE method, we apply the Weighted Sum using Update Matrix (WSUM) scheme to the step of calculating the instantaneously estimated channel and then, a time domain selectively averaging method is applied after the WSUM scheme. Based on that, the accuracy of instantaneously estimated channel increases and then, the accuracy of auto covariance matrix also increases. Consequently, we can achieve the performance gain over the conventional MMSE method. Through simulations based on the IEEE 802.11p standard, it is confirmed that the proposed scheme can outperform the existing channel estimation schemes.

• Journal of Power Electronics
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• v.9 no.4
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• pp.604-611
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• 2009

A dP/dV feedback-controlled MPPT (Maximum Power Point Tracking) method for photovoltaic power systems using II-SEPIC (Isolated Inverse-SEPIC; Single Ended Primary Inductance Converter) is presented and a current-mode dP/dV feedback-controlled MPPT method is devised to apply for the PV power converter system. A control strategy for the current-mode dP/dV feedback control system is developed in this paper and the proposed MPPT shows relatively satisfactory dynamics against rapidly changing insolation conditions. In order to verify the validity and effectiveness of the proposed method, simulations and experiments of the PV power system using II-SEPlC converter are performed. These simulation and experiment results show that the proposed method enables the PV power system to extract maximum power from the photovoltaic module against the solar insolation variation.

• Bulletin of the Korean Mathematical Society
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• v.49 no.6
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• pp.1179-1192
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• 2012

In this paper, we consider a doubly nonlinear parabolic partial differential equation $\frac{{\partial}{\beta}(u)}{{\partial}t}-{\Delta}_pu+f(x,t,u)=0$ in ${\Omega}{\times}[0,T]$, with Dirichlet boundary condition and initial data given. We prove the existence of a discrete approximate solution by means of the Rothe discretization in time method under some conditions on ${\beta}$, $f$ and $p$.

• Macromolecular Research
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• v.17 no.11
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• pp.907-911
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• 2009

To improve the moisture stability of the $CaS:Eu^{2+}$ red phosphor, surface coatings with silica nanoparticles were performed using five different methods, i.e., $P_1$, $P_2$, $P_3$, $P_4$, and $P_5$. The phosphors were coated with silica nanoparticles using a dip coating method ($P_1$) and sol-gel method ($P_2$). The phosphors were coated using a solution containing silica nanoparticles and poly(1-vinyl-2-pyrrolidone), PVP, $(P_3$). The phosphors were also coated with silica nanoparticles by reacting with the 1-vinyl-2-pyrrolidone (VP) monomer ($P_4$) or by reacting with mixtures containing VP and tetraethylorthosilicate ($P_5$). A decrease in the photoluminescence (PL) intensity was observed regardless of the coating methods. However, the moisture stability of the phosphors was enhanced by the coating when aged in a temperature-controlled humidity chamber. Among these methods, the $P_4$ (or $P_5$) method exhibited the greatest increase in moisture stability of the phosphors. The coated phosphors showed a relatively constant intensity with aging time, whereas the uncoated phosphor showed a decrease.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.2
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• pp.53-59
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• 1986

On the slamming analysis of ship design the data for the impact pressure acted on the forward bottom of a ship are needed. Furthermore impact pressure is given by the function of both the hull form coefficient and relative velocity. In this papper. a simplified method to estimate hull form coefficient by perso;,al computer (p. c.) is studied. This numerical analysis was applied to the model of the Mariner type. and then the result by the p. c. was compared with that by IBM 7090 computer. Main results obtained are as follows: 1. The result by the developed p. c. method had fairly good agreement with that by conventional large computer (IBM 7090) within 2% error. 2. This developed method' by p. c. may be applied to the initial estimation of the K-value because of the close agreement between the ship lines by the results of p. c. and that of input.

• 보존과학연구
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• s.20
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• pp.21-47
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• 1999

According to damage of papers by the chemical cause, papers become to acidify. Among the 3 kinds of method measuring the acidity of paper, one was nondestructive method measuring the surface of the paper by flat type electrode and the others were destructive methods measuring directly by cold water extract method and hot water extract method. In case of the cellulolytic cultural properties, the latter methods were not applied because those methods must bedissociated papers. To measure the paper acidity nondestructively, we investigated the correlation of the nondestructive method and the destructive methods. The conclusions are as follows. 1) In the relationship of the cold water extract method and the hot water extract method, It was indicated that the pH measured by the hot water extract method was high quality printing paper 0.08, rough printing paper 0.13, and Korean paper 0.29 higher than that by the cold water extract method.2) In the relationship of the cold water extract method and the surface measurement method, It showed that the pH value measured by the cold water extract method was high quality printing paper 1.86, rough printing paper 0.80,and Korean paper 0.58 higher than value that by the surface measurement.3) In the relationship of the hot water extract method and the surface measurement method, It showed that the pH value measured by the hot ABSTRACT water extract method was high quality printing paper 1.78, rough printing paper 0.66, and Korean paper 0.29 higher than that by the surface measurement. From the above-mentioned results, the pH value measured by the surface measurement was need to high about 1.78∼1.86 in high quality printing paper, 0.66-0.80 in rough printing paper, and 0.29∼0.58 in Korean paper and the surface measurement with flat type electrode was very available to measure the acidity of Korean papers actually.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.125-142
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• 2004

We analyze the convergence properties of Powell's UOBYQA method. A distinguished feature of the method is its use of two trust region radii. We first study the convergence of the method when the objective function is quadratic. We then prove that it is globally convergent for general objective functions when the second trust region radius p converges to zero. This gives a justification for the use of p as a stopping criterion. Finally, we show that a variant of this method is superlinearly convergent when the objective function is strictly convex at the solution.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.619-627
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• 2008

In this study, through dissipation test of DMT predicted Horizontal Coefficient of Consolidation at marine clay. CPTu Dissipation test, laboratory consolidation test compared with $C_v$, through it examined application. The result, DMT calculated horizontal coefficient of consolidation by $P_2$-Log(t) method of DMT-A method and C-$\surd$t(min) method. This horizontal coefficient of consolidation calculated larger than $P_2$-Log(t) method. $P_2$-Log(t) method of DMT, Torstensson of CPTu and Houlsby & Teh(1991) appeared similar to tend. This approximate value is possible application in marine clay. It'll need to study continuously through collection of data.

• Journal of Mushroom
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• v.2 no.1
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• pp.42-43
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• 2004

Labor required for managing and harvesting the oyster mushroom bed was evaluated. Although vinyl mulching cultivation method needs more hours for spawning, it saves more than 50% of labor for harvesting and managing of the mushroom bed. Harvesting hour of 1st-3rd flush in vinyl mulching method was 48~50% for Plerutus ostreatus and 36~41% for P. sajor-caju. Labor for bed management after harvesting in vinyl mulching method was also 38~50% for P. ostreatus compared to conventional method, and 20~35% for P. sajor-caju. Vinyl mulching is believed to be a very efficient method for saving labor in oyster mushroom cultivation.