• Fibers and Polymers
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• v.1 no.1
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• pp.25-31
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• 2000

Poly(3-hexyl thiophene)(P3HT) and poly(3-dodecyl thiophene)(P3DT) were polymerized by oxidative coupling with ferric chloride. The P3HT light-emitting device emitted red light and it could be observable in the ordinary indoor light. The device had the turn-on electric field of about 3$\times$$10^7$ V/m. The maximum electroluminescene (EL) intensity was obtained when the thickness of polymer layer was about 130 nm in IT0/P3HT/Al device. The maximum external quantum yield was 0.002%. The maximum luminance was 21 cd/$m^2$. The EL intensity decreases with increasing the crystallinity of the polymer layer. By using the oriented poly(3-alkyl thiophene)(PAT) layer as an electroluminescent layer in the ITO/polymer/Al light-emitting devices, the polarized EL light emission was observed. The EL intensity ratio of parallel to perpendicular direction to the stretch direction for P3HT was about 1.40.

• Journal of the Korean Ceramic Society
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• v.24 no.5
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• pp.431-436
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• 1987

High purity Al2O3 has been extracted from serlcite of clayminerals, selicite was treated by H2SO4(2N∼18N) solution, NH4OH treatment(PH8.5∼10.0) and metallic impurities such as Fe were removed by NaOH treatment. The tendency of extraction yield of ${\alpha}$-Al2O3 have been investigated by relating reaction time, acid concentration. Reaction products were analyzed by DT-TGA, chemical analysis and X-ray diffractometer. Prepared ${\alpha}$-Al2O3 power is fired in air at 1400$^{\circ}C$, 1600$^{\circ}C$ 2hr. The results are as follows; 1. The most suitable extracting conditions of ${\alpha}$-Al2O3 from Selicite were N-H2SO4, 120 min acidtreating time. 2. The optimum pH condition was 9.0. 3. Physical properties of sintered Al2O3 bodies were as follows. Relative density is 99%. Water absorption is 0.26%. Rock well hardness is 89.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.304-307
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• 1999

The Mg($_{1-x}$ )S $r_{x}$Ti $O_3$(x=0.1,0.2,0.3) ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with calcining temperature and composition ratio by XRD and DT-TGA. Increasing the calcining temperature from 80$0^{\circ}C$ to 100$0^{\circ}C$, second phase was decreased and average particle size was increased. The SrTi $O_3$ ceramics of calcined at 100$0^{\circ}C$ had a structure of polycrystalline perovskite without the secondary phases. The average particle size of the $Mg_{0.9}$S $r_{0.1}$Ti $O_3$ ceramics calcined at 100$0^{\circ}C$ were 0.67${\mu}{\textrm}{m}$..>......

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.425-428
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• 2001

In this work, we propose a new optical configuration for a 3-stack color LCD using subtract color mixing method. This configuration consists of 3 color polarizers, a neutral polarizer and 3 LC cells. With the proposed configuration, we can increase the contrast ratio practically by using a neutral polarizer and reduce the manufacturing cost. To reduce wavelength dispersion, the sequence of polarizers is optimized.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.203-204
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• 2012

본 논문에서는 3-레벨 ANPC 방식을 적용하여 하이브리드 자동차에 장착된 IPMSM을 구동하는 인버터를 제안하였다. 3-레벨 ANPC 인버터는 전력 반도체 스위치의 열 분배에 용이하다. 또한 3-레벨 인버터의 경우 dv/dt가 작기 때문에 THD를 감소시켜 출력 필터의 부피와 EMI를 저감 시킬 수 있다. 따라서 자동차의 신뢰성과 안전성을 높일 수 있다. 제안된 논문에서는 2-레벨 인버터와 3-레벨 ANPC 인버터 출력 특성을 분석하고, 스위치 간 온도 특성 분석 및 THD를 시뮬레이션 통하여 비교하였다.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.4
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• pp.369-379
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• 2018

Let ${\mathbb{H}}_3$ be the 3-dimensional Heisenberg group equipped with a left-invariant metric. In this paper we calculate the volumes of geodesic balls in ${\mathbb{H}}_3$. Let $B_e(R)$ be the geodesic ball with center e (the identity of ${\mathbb{H}}_3$) and radius R in ${\mathbb{H}}_3$. Then, the volume of $B_e(R)$ is given by $$Vol(B_e(R))={\frac{\pi}{6}}\{-16R+(R^2+6){\sin}\;R+(R^3+10R){\cos}\;R+(R^4+12R^2){\int\nolimits_0^R}\;{\frac{{\sin}\;t}{t}}dt\}$$.

• Journal of Information Science Theory and Practice
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• v.3 no.3
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• pp.45-63
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• 2015

The word ‘growth’ represents an increase in actual size, implying a change of state. In science and technology, growth may imply an increase in number of institutions, scientists, or publications, etc. The present study demonstrates the growth of neurology literature for the period 1961-2010. A total of 291,702 records were extracted from the Science Direct Database for fifty years. The Relative Growth Rate (RGR) and Doubling Time (Dt.) of neurology literature have been calculated, supplementing with different growth patterns to check whether neurology literature fits exponential, linear, or logistic models. The results of the study indicate that the growth of literature in neurology does not follow the linear, or logistic growth model. However, it follows closely the exponential growth model. The study concludes that there has been a consistent trend towards increased growth of literature in the field of neurology.

• Restorative Dentistry and Endodontics
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• v.27 no.6
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• pp.632-643
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• 2002

The purpose of this study was two-fold. First was to evaluate whether the molecular sieving model was appropriate for ionic dissociation experiment. Second was to compare the dissociation of calcium and hydroxyl ions from five types of calcium hydroxide pastes (Pure calcium hydroxide paste, DT temporary $dressing^{\circledR},{\;}Metapaste^{\circledR},{\;}Chidopex^{\circledR},{\;}Metapex^{\circledR}$) in three vehicles (aqueous, viscous and oily) and the antibacterial effect. Each calcium hydroxide pastes was placed into 0.65ml tube with cap and then 15% polyacrylamide gel was placed onto calcium hydroxide pastes. After the gel was hardened, the tubes were filled with tridistilled water (pH 7.14) and closed with cap. The tubes were stored in $37^{\circ}C$ 100% incubator The pH reading and the concentration of calcium ions were taken at 1, 4, 7. 10, and 14 days. The brain heart infusion agar plates with S. mutans and A. actinomycetemcomitans were used far antibacterial activity test. Middle of agar plate was filled with the calcium hydroxide pastes. The plates were incubated at $37^{\circ}C$ and observations were made to detect the zones of inhibition. These data were evaluated statistically by use of the analysis of variance and duncan test. The results were as follows. 1. In fresh mixing state, the pH of five types of calcium hydroxide pastes were measured between 12.5 and 12.8. 2. The pH was increased in all five types of calcium hydroxide pastes compared with control group. In 14 days, Pure calcium hydroxide paste (11.45) and DT temporary $dressing^{\circledR}$ (11.33) showed highest pH, followed by $Metapaste^{\circledR}$ (9.49), $Chidopex^{\circledR}$ (8.37) and $Metapex^{\circledR}$ (7.59) 3. Calcium was higher in all five types of calcium hydroxide pastes compared with control group. In 14 days, Pure calcium hydroxide paste (137.29 mg%) and DT temporary $dressing^{\circledR}$ (124.6 mg%) showed highest value, followed by $Metapaste^{\circledR}$ (116.74 mg%), $Chidopex^{\circledR}$ (111.84 mg%) and $Metapex^{\circledR}$ (60.22 mg%). 4. The zones of bacterial inhibition were seen around all five types of calcium hydroxide pastes. $Chidopex^{\circledR}{\;}and{\;}Metapex^{\circledR}$ groups which include iodoform were observed significantly larger zone of inhibition in A. actinomycetemcomitans compared with the other calcium hydroxide groups (p<0.05) However, $Metapex^{\circledR}$ showed the least antibacterial effect on S. mutans compared with other groups (p<0.05). The molecular sieving model was found to be acceptable in dissociation experiment of hydroxyl and calcium ions when compared with the previous tooth model study. But this model was not appropriate for the antibacterial test.

• The Korean Journal of Pharmacology
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• v.13 no.2
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• pp.11-17
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• 1977

The effects of varing concentrations of extracellular potassium on the positive inotropic actions of Aconiti tuber butanol fraction and ouabain were studied on isolated left atrium of rat. The patterns of active tension increment, such as time to peak and total duration of tension development, was contrasted in Aconiti tuber butanol fraction to ouabain. Ouabain did not induce significant shortening in time to peak and total duration of tension development, but Aconiti tuber produce significant shortening. The isometric tension and peak dF/dt were not significantly different at the range of extracellular potassium concentration $2mEq{\sim}10mEq$ per. liter in control studies. The ouabain-induced increase in active tension and peak dF/dt at 2mEq. per. liter potassium concentration was significantly different from that of 6mEq or 10mEq. per. liter, but there was no difference between 6mEq and 10mEq. per. liter. but Aconiti tuber is not. In contrast to ouabain, Aconiti tuber butanol fraction did not show potassium dependent positive inotropic effect. It produced almost same increment of tension and peak dF/dt at all the concentration of extracellular potassium concentrations in this experiment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.1
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• pp.104-108
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• 2006

Effect of gamma irradiation on the softening of dried fernbrake at different moist-heating conditions was investigated. Dried fernbrake packaged in controlled atmosphere $(CO_2\;25\%,\;N_2\;75\%)$ was irradiated up to 7 kGy with $\gamma-ray$. Hardness of dried fernbrake was significantly decreased at the irradiation dose of above 5 kGy. Hardness of cooked fernbrake was significantly decreased with increasing irradiation dose level as well as heating temperature and time. $DT_{50}$ value (The heating time required to reach the $50\%$ reduction of hardness) for irradiated fernbrake was shortened according to dose level as well as heating temperature and heating time: $DT_{50}$ value of control: 23 min, 5 or 7 kGy: $2.2\~5.0$ min at $60^{\circ}C$. Also, the activation energy for softening of irradiated fernbrake ($1.85\~1.88$ kcal/mole for $5\~7kGy$) decreased compared to control (4.30 kcal/mole). Moisture content, swelling and rehydration rate of gamma irradiated fernbrake during moist heating increased according to the irradiation doses. Sensory results showed that scores of off-flavor and odor in irradiated fernbrake upto 7 kGy were not significantly different from control. Based on these results, gamma irradiation was effective for the reduction of cooking time and the activation energy for softening of dried fernbrake with increasing dose levels.