• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.51-54
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• 2000

In variable structure control algorithm, sliding mode makes the closed loop system insensitive to modelling uncertainties and external disturbances. However due to imperfections in switching, the system trajectory chatters, which is very undesirable. And the insensitivity property of a sliding mode controller is present only when the system is in the sliding mode. To overcome these shortcomings, in this paper, new sliding mode control algorithm using time-varying sliding surface and fuzzy PI structrue is proposed.

• Bulletin of the Korean Mathematical Society
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• v.30 no.2
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• pp.251-263
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• 1993

The purpose of this paper is to study the solvability of the equation (E). In Section 2, we give preliminary definitions. In Section 3, we prove related two results (Theorem 1 and Corollary 1) concerning the closedness property of accretive operators in the class of spaces whose nonempty bounded closed convex subsets have the fixed point property for nonexpansive self-mapping. Using therem 1, we derive a result (Theorem 2) on the range of accetive operators in (.pi.)$_{1}$ spaces with a view to establishing a new result, which improves a result of Kartsatos [8] and Webb [15]. Further, we give an interesting consequence (Corollary 3) of Theorem 2. In section 4, we apply Corollary 1 to obtain two results (Theorem 3 and 4) for the range of sums of two accretive operators, which generalize two results of Reich [12].

• Bulletin of the Korean Mathematical Society
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• v.42 no.3
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• pp.571-577
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• 2005

In this paper we prove that if T is a k-th root of a p­hyponormal operator when T is compact or T$^{n}$ is normal for some integer n > k, then T is (generalized) scalar, and that if T is a k-th root of a semi-hyponormal operator and have the property $\sigma$(T) is contained in an angle < 2$\pi$/k with vertex in the origin, then T is subscalar.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.868-871
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• 2006

In-plane switching characteristics of PI rubbed ITO sandwich cell with low molecule FLC (ferroelectric liquid crystal) surface was investigated. FLC on the surface is governed by the applying frequency and surface condition. By controlling the Ps (spontaneous polarization) direction of dual FLC surfaces, switching characteristics are improved without change of cell structure.

• Journal of Integrative Natural Science
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• v.3 no.2
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• pp.107-111
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• 2010

Silicon-containing ${\pi}$-conjugated compounds, especially silacyclopentadienes (siloles), have emerged as a new class of electroactive materials with good electron transport properties in OLEDs. 9,9'-spiro-9-silabifluorene compound as well as its starting material 2,2'-dibromobiphenyl have been synthesized with higher yields. Spirosilabifluorene is expected to be an efficient host material for the blue-light emitting diodes. 9,9'-spiro-9-silabifluorene, 1,1-dichloro-1-silafluorene, and 1,1-dimethyl-1-silafluorene were characterized by $^1H$-NMR, UV/Vis and photoluminescence spectroscopy.

• Journal of applied mathematics & informatics
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• v.38 no.5_6
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• pp.579-590
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• 2020

The flatness property of a unilateral weighted shifts is important to study the gaps between subnormality and hyponormality. In this paper, we first summerize the results on the flatness for some special kinds of a weighted shifts. And then, we consider the flatness property for a local-cubically hyponormal weighted shifts, which was introduced in [2]. Let α : ${\sqrt{\frac{2}{3}}}$, ${\sqrt{\frac{2}{3}}}$, $\{{\sqrt{\frac{n+1}{n+2}}}\}^{\infty}_{n=2}$ and let W_α be the associated weighted shift. We prove that W_α is a local-cubically hyponormal weighted shift W_α of order ${\theta}={\frac{\pi}{4}}$ by numerical calculation.

• Honam Mathematical Journal
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• v.42 no.1
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• pp.93-103
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• 2020

This article concerns a property of Abelain π-regular rings. A ring R shall be called right quasi-DR if for every a ∈ R there exists n ≥ 1 such that C(R)aⁿ ⊆ aR, where C(R) means the monoid of regular elements in R. The relations between the right quasi-DR property and near ring theoretic properties are investigated. We next show that the class of right quasi-DR rings is quite large.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.99-105
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• 2022

As the chip size gets smaller, the width of the electrode line is also fine, and the density of interconnections is increasing. As a result, RC delay is becoming a problem due to the difference in resistance between the capacitor layer and the electrical conductivity layer. To solve this problem, the development of electrodes with high electrical conductivity and dielectric materials with low dielectric constant is required. In this study, we developed low dielectric ink by mixing commercial PSR which protect PCB's circuits from external factors and PI with excellent thermal property and low-k characteristics. As a result, the ink mixture of PSR and PI 10:3 showed the best results, with a dielectric constant of about 2.6 and 2.37 at 20 GHz and 28 GHz, respectively, and dielectric dissipation was measured at about 0.022 and 0.016. In order to verify the applicability of future applications, various line-width transmission lines produced on Teflon were evaluated, and as a result, the loss of transmission lines using low dielectric ink mixed with PI was 0.12 dB less on average in S21 than when only PSR was used.

• The Pure and Applied Mathematics
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• v.10 no.4
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• pp.199-206
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• 2003

Let N be a right near-ring. N is said to be strongly reduced if, for $a\inN$, $a^2 \in N_{c}$ implies $a\;\in\;N_{c}$, or equivalently, for $a\inN$ and any positive integer n, $a^{n} \in N_{c}$ implies $a\;\in\;N_{c}$, where $N_{c}$ denotes the constant part of N. We will show that strong reducedness is equivalent to condition (ⅱ) of Reddy and Murty's property $(^{\ast})$ (cf. [Reddy & Murty: On strongly regular near-rings. Proc. Edinburgh Math. Soc. (2) 27 (1984), no. 1, 61-64]), and that condition (ⅰ) of Reddy and Murty's property $(^{\ast})$ follows from strong reducedness. Also, we will investigate some characterizations of strongly reduced near-rings and their properties. Using strong reducedness, we characterize left strongly regular near-rings and ($P_{0}$)-near-rings.

• Polymer(Korea)
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• v.37 no.4
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• pp.547-552
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• 2013

Polyimide (PI) containing carboxyl functional group was prepared and reacted with diaminosiloxane during high temperature film casting. The morphology of resulting film was observed by using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), which revealed that globular 100 nm-sized PI domains and continuous polysiloxane phase were formed. X-ray photoelectron spectroscopy (XPS) study indicated that air-film interface mainly consisted of polysiloxane blocks. Poly(imidesiloxane) thin layer was thermostable until $400^{\circ}C$ and its pressure- sensitive adhesive property was retained up to $300^{\circ}C$. The comparative experiments revealed that grafting between carboxyl groups of polyimide and aminosiloxane was crucial for formation of microdomain structure and pressure-sensitive adhesive property.