• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.150-157
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• 2017

Three types of piezoelectric single crystals [PMN-PT (Generation I $[Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3]$), PMN-PZT (Generation II $[Pb(Mg_{1/3}Nb_{2/3})O_3-Pb(Zr,Ti)O_3]$), PMN-PZT-Mn (Generation III)] were grown by the solid-state single crystal growth (SSCG) method, and their dielectric and piezoelectric properties were measured and compared. Compared to (001) PMN-PT and PMN-PZT single crystals, the (001) PMN-PZT-Mn single crystals exhibited a higher transition temperature between the rhombohedral and tetragonal phases ($T_{RT}=144^{\circ}C$), as well as a higher coercive electric field ($E_C=6.3kV/cm$) and internal bias field ($E_I=1.6kV/cm$). The (011) PMN-PZT-Mn single crystals showed the highest coercive electric field ($E_C=7.0kV/cm$), and the highest stability of $E_C$ and $E_I$ during 60 cycles of polarization measurement. These results demonstrate that both Mn doping (for higher electromechanical quality factor ($Q_m$)) and a (011) crystallographic orientation (for higher coercive electric field and stability) are necessary for high power transducer applications of these piezoelectric single crystals. Specifically, the (011) PMN-PZT-Mn single crystal (Gen. III) had the highest potential for application in the fields of SONAR transducers, high intensity focused ultrasound (HIFU), ultrasonic motors, and others.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.319-325
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• 1999

Direct current(d.c.)leakage current voltage characteristics of radio-frequencymagnetron sputtered BaTa\sub 2\O\sub 6\ film capacitors with aluminum(A1) top and indium tin oxide (ITO) bottom electrodes have been investigatedas a function of applied field and temperature. In order to study surfacetreatment effect on the electrical characteristics of as-deposited film weperformed exposure of oxygen plasma on $BaTa_2O_6$ surface. d. c.current-voltage (I-V), bipolar pulse charge-voltage (Q-V), d. c. current-time (I-t) andcapacitance-frequency (C-f) analysis were performed on films. All ofthe films exhibita low leakage current, a high breakdown field strength (3MV/cm-4.5MV/cm), and high dielectric constant (20-30). From the temperature dependence of leakage current,we can conclude that the dominant conduction mechanism is ascribed toSchottky emission at high electric field (>1MV/cm) and hopping conduction at lowelectric field (<1MV/cm). According to our results, the oxide plasma surfacetreatmenton as-deposited $BaTa_2O_6$ resulted in lowering interfacebarrier height and thus, leakage current when a negative voltage applied to the A1 electrode. This can be explained by reduction of surface contamination via etching surface and filling defects such as oxygen vacancies.

• Polymer(Korea)
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• v.30 no.3
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• pp.271-278
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• 2006

In order to investigate the structure and dynamics of atatic poly (vinyl alcohol) (PVA)/water system, laser light scattering experiment has been done in the semi-dilute concentration regime at $25^{\circ}C$. The scattering intensity I(q) can be analyzed with the fractal equation of $I(q){\sim}q^{-m}$ instead of Onstein-Zernike type equation. The fractal dimensionality m was found to be constant after reaching the plateau value of $m=2.6{\pm}0.3$ above C=3wt%. The time correlation function of dynamic light scattering has always two different modes such as fast mode and slow one. The cooperative diffusion of fast mode showed concentration independence contrary 4o the reptation theory's concentration dependent exponent of 3/4. The slow mode can be interpreted as the motion of large scale heterogeneities and its strong concentration dependence is apparent with a large negative exponent of -3.0. It is considered that the stereo-regular arrangement with four successive meso units of -OH plays as a key role in forming such heterogeneity.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1487-1489
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• 1994

$(Zr_{0.65}Sn_{0.35})Ti_{1.04}O_4$ system which has a dielectric constant, low dielectric loss and temperature coefficient was investigated. Temperature coefficient varied from positive to negative with increasing of NiO. For the NiO content 1.0wt%. i.e $(Zr_{0.65}Sn_{0.35})Ti_{1.04}O_4$, the ceramic showed very good dielectric properties such as ${\epsilon}$=37.8, $Q{\times}f_o=49.000$ and ${\tau}_r= 4{\pm}1ppm/^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.17-23
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• 1992

A ($Pb_{1-x}Ca_{x})ZrO_{3}$ system which has a high dielectric constant, low dielectric loss and temperature coefficient was investigated. For sintering temperatures above 1350$^{\circ}C$ the microstructures of sintered bodies were unchanged regardless of the amount of CaO. The dielectric constant and dielectric loss decreased and the temperature coefficient varied from positive to negative with the increasing amount of CaO. For the CaO content of 0.37, i.e. ($Pb_{0.63}Ca_{0.37})ZrO_{3}$, the ceramic showed very good dielectric properties such as ${\varepsilon}_1$=100, Q > 1200 at 3GHz, and T$_f$=$\pm$3ppm/$^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.788-793
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• 2002

The glass-electroceramics were composed of glass composition(CaO, $SiO_2$, $B_2$ $O_3$) and electroceramic composition(BaO, N $d_2$ $O_3$, B $i_2$ $O_3$ and Ti $O_2$) Their dielectric properties have been investigated as a function of sintering temperature and glass contents. In the ceramics composed of 0.16BaO-0.15(N $d_{0.87}$,B $i_{0.13}$)$_2$ $O_3$-0.69Ti $O_2$with glass ［EG-2782］ 3wt% addition and sintered at 108$0^{\circ}C$ for 2h, we could obtain microwave properties of dielectric constant $\varepsilon$$_{r}$ = 80.1, quality factor Q $\times$f = 810(at 3.5 GHz) and temperature coefficient of resonant frequency $\tau$$_{f}$ = -1.3 ［ppm/$^{\circ}C$］. These experimental results show that dielectric constant and temperature coefficient of resonant frequency could be estimated by empirical equations involving the rule of mixture.e.

• Economic and Environmental Geology
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• v.9 no.4
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• pp.225-240
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• 1976

This study deals with the flow of bed rock ground water of Banyaweol Formation, which is presently cleared up as a laminar flow. The result obtained may be summarized as the following. 1) The Banyaweol Formation consists mainly of thin-bedded, green to blackish green shale, mudstone, and marl. The marl and mudstone alternatively occur with shale. The marl and mudstone form a aquifer of Banyaweol Formation. In this study, a group of aquifer is in convenience named as a aquifer zone. The aquifer occurs in lenticular form. The aquifer seems to be a type of artesian aquifer because it is covered with aquicludes, but it actually forms a unconfined aquifer because its piezometric surface stays under the lower aquiclude. The lowering of piezometric level is formed because of leakage of the ground water to the lower aquifer undersaturated. 2) The coefficient of permeability of Banyaweol Formation's ground water body (K) is derived by using Dupuit's equation as the following ${\log}K=\frac{CK^2-dK+f}{aK-b}\;\(M=1.365(2H-s)s\\M={\log}1.956s{\sqrt{H}}r\)$ here, $$a=\sum_{1}M_iG_i$$ $$b={\frac{1}{2}log{\sum_{i}}Q_i{^2}$$ $$c=2{\sum_{i}}M_i{^2}$$ $$d=loge{\sum_{i}}M_{i}Q_{i}+2{{\sum_{i}}N_{i}Q_{i}$$ $$f=loge{\sum_{i}}Q_i{^2}N_i$$ If the measured values substituted for the above equation, the coefficient of permeability of the aquifer is 4.1m/day. The coefficient of storge of the aquifer is $2.8{\times}10^{-4}$ if the measured values substituted for Theis's equation. Using the above constants, the filtration velocity of the aquifer is $2.1{\times}1O^{-1}m/day$and the daily flow quantity of the ground water is $847.38m^{3}/day$. 3) In order to understand the time necessary for a circulation of ground water body, the contents of tritum contained in the ground water are measured as 2.3 T.U. at the Korea Atomic Energy Research Institute. Before 1952, the average concentration of tritium per year in groundwater was reported as 10T. u., taking it as the standard, the groundwater of the present study 26.25 years old. Therofore, the groundwater of the Banyaweol Formation is judged as an relatively old groundwater. It is characteristic that the ground water of Banyawol Formation is laminar flow as well as unconfined aquifer and ground water flow of relatively long time. 4) The nature, means of flow, and circulation of Banyaweol Formation's ground water body make it possible set up this ground water body as a ground water system.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.66-83
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• 2002

Recently, we have provided evidence that ginsenosides, the active components of Panax ginseng, utilize pertussis toxin (PTX)-insensitive $G{\alpha}_{q/11}-phospholipase\;C-{\beta}3(PLC-{\beta}3)$ signal transduction pathway for the enhancement of $Ca^{2+}-activated\;Cl^{-}$ current in the Xenopus oocyte (British J. Pharmacol. 132, 641-647, 2001; JBC 276, 48797-48802, 2001). Other investigators have shown that stimulation of receptors linked to $G{\alpha}-PLC$ pathway inhibits the activity of G proteincoupled inwardly rectifying $K^+$ (GIRK) channel. In the present study, we sought to determine whether ginsenosides influenced the activity of GIRK 1 and GIRK 4 (GIRK 1/4) channels expressed in the Xenopus oocyte, and if so, the underlying signal transduction mechanism. In oocyte injected with GIRK 1/4 channel cRNAs, bath-applied ginsenosides inhibited high potassium (HK) solution-elicited GIRK current $(EC_{50}:4.9{\pm}4.3\;{\mu}g/ml).$ Pretreatment of the oocyte with PTX reduced the HK solution-elicited GIRK current by $49\%,$ but it did not alter the inhibitory ginsenoside effect on GIRK current. Prior intraoocyte injection of cRNA(s) coding $G{\alpha}_q,\;G{\alpha}_{11}\;or\;G{\alpha}_q/G{\alpha}_{11},\;but\;not\;G{\alpha}_{i2}\;or\;G{\alpha}_{oA}$ attenuated the inhibitory ginsenoside effect. Injection of cRNAs coding $G{\beta}_{1{\gamma}2}$ also attenuated the ginsenoside effect. Similarly, injection of the cRNAs coding regulators of G protein signaling 1, 2 and 4 (RGS1, RGS2 and RGS4), which interact with $G{\alpha}_i\;and/or\;G{\alpha}_{q/11}$ and stimulates the hydrolysis of GTP to GDP in active GTP-bound $G{\alpha}$ subunit, resulted in a significant reduction of ginsenoside effect on GIRK current. Preincubation of GIRK channel-expressing oocyte in PLC inhibitor (U73122) or protein kinase C (PKC) inhibitor (staurosporine or chelerythrine) blocked the inhibitory ginsenoside effect on GIRK current. On the other hand, intraoocyte injection of BAPTA, a free $Ca^{2+}$ chelator, had no significant effect on the ginsenoside action. Taken together, these results suggest that ginsenosides inhibit the activity of GIRK 1/4 channel expressed in the Xenopus oocyte through a PTX-insensitive and $G{\alpha}_{q/11}$-,PLC-and PKC-mediated signal transduction pathway.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.131-134
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• 2001

In this paper, the piezoelectric and dielectric properties as a function of x and a in $aPbZr_xTi_{1-x}O_3-(1-a)Pb(Mn_{1/3}Nb_{2/3})O_3$ + ywt%MgO is investigated. As a results, when a is 0.95 and x is 0.505, electromechanical coupling factor$(k_p)$, permittivity${\varepsilon}_33^T/{\varepsilon}_0$, piezoelectric strain constant$(d_{33})$ and mechanical quality factor$(Q_m)$ are 58 %, 1520, 272 pC/N and 1550, respectively. From XRD analysis, when x is 0.505, it is MPB which present rhombohedral and tetragonal phase in same quantity. Also, From SEM observation, when sintering temperature is $1150^{\circ}C$, grain size is about $2\;{\mu}m$. As a results added MgO dopant in the ternary piezoelectric ceramic, when MgO content is 0.1 wt%, $k_p$ increases to 63[%].

• Journal of the Korean Mathematical Society
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• v.54 no.4
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• pp.1121-1148
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• 2017

Go is an ancient game of great complexity and has a huge following in East Asia. It is also very rich mathematically, and can be played on any graph, although it is usually played on a square lattice. As with any game, one of the most fundamental problems is to determine the number of legal positions, or the probability that a random position is legal. A random Go position is generated using a model previously studied by the author, with each vertex being independently Black, White or Uncoloured with probabilities q, q, 1 - 2q respectively. In this paper we consider the probability of legality for two scenarios. Firstly, for an $N{\times}N$ square lattice graph, we show that, with $q=cN^{-{\alpha}}$ and c and ${\alpha}$ constant, as $N{\rightarrow}{\infty}$ the limiting probability of legality is 0, exp($-2c^5$), and 1 according as ${\alpha}$ < 2/5, ${\alpha}=2/5$ and ${\alpha}$ > 2/5 respectively. On the way, we investigate the behaviour of the number of captured chains (or chromons). Secondly, for a random graph on n vertices with edge probability p generated according to the classical $Gilbert-Erd{\ddot{o}}s-R{\acute{e}}nyi$ model ${\mathcal{G}}$(n; p), we classify the main situations according to their asymptotic almost sure legality or illegality. Our results draw on a variety of probabilistic and enumerative methods including linearity of expectation, second moment method, factorial moments, polyomino enumeration, giant components in random graphs, and typicality of random structures. We conclude with suggestions for further work.