• 한국생산제조학회지
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• 제7권6호
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• pp.1-11
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• 1998

This paper presents performance analyses of three types of the cylindrical-type ER(electro-rheo-logical) valves, which have different electrode length and width but same electrode area. Following the composition of silicone oil-based ER fluid, the field-dependent yield stresses are obtained from experimental investigation on the Bingham property of the ER fluid. The ER valve which is dependent on the applied electric field is devised and its theoretical model is derived. On the basis of the pressure-drop analysis, three types of the ER valves are designed and manufactured. After experimentally evaluation field-dependent pressure drops, PI controller is formulated to achieve tracking control on desired pressure drop. The controller is then experimentally implemented and tracking control performance is presented in order to demonstrate superior controllability of the ER valve. In addition, the response characteristic of the ER valve with respect to the excitation frequency of the electric fiedls is provided to show the feasibility of practical application.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.196-204
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• 1996

The simplified dynamic models of the timer assembly in the diesel engine fuel injection system were developed. The first order system with time delay was assumed and the various parameters in this model were obtained by experimental data. These simplified dynamic models were used for the development of control algorithm of the injection timing control system. The PI control algorithm was modified to include the anti-windup property and disturbance compensation. This modified PI control algorithm was used for the control of the injection timing. Improved control accuracy and reduced control efforts were observed.

• 대한수학회보
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• 제26권2호
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• pp.109-114
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• 1989

This paper deals with the classifying spaces of finite groups. To any finite group G we associate a space BG with the property that .pi.$_{1}$(BG)=G, .pi.$_{i}$ (BG)=0 for i>1. BG is called the classifying space of G. Consider the problem of finding a stable splitting BG= $X_{1}$$^{V}$ $X_{1}$$^{V}$..$^{V}$ $X_{n}$ localized at pp. Ideally the $X_{i}$ 's are indecomposable, thus displaying the homotopy type of BG in the simplest terms. Such a decomposition naturally splits $H^{*}$(BG). The main purpose of this paper is to give the classification theorem in stable homotopy theory for groups with periodic cohomology i.e. cyclic Sylow p-subgroups for p an odd prime and to calculate some universal stable element. In this paper, all cohomology groups are with Z/p-coefficients and p is an odd prime.prime.

• Journal of Photoscience
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• 제9권3호
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• pp.51-55
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• 2002

The 77 K emission and excitation spectra, and 298 K infrared and absorption spectra of [Cr(progly)(2,2-tri)]CIO$_4$[progly=prolylglycinate,2,2-tri=N-(2-aminoethyl)-1,2-ethanediamine] have been measured. The vibrational intervals of the electronic ground state are extracted from emission and infrared spectra. The twelve electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the observed electronic transitions, a ligand field analysis was performed to determine the metaligand bonding properties for the coordinated atoms. It is found that the carboxylate oxygen of the progly is a strong $\sigma$-and $\pi$-donor while the peptide nitrogen has weak $\pi$-donor property toward chromium(III) ion.

• 대한수학회지
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• 제51권4호
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• pp.751-771
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• 2014

We study the structure of idempotents in polynomial rings, power series rings, concentrating in the case of rings without identity. In the procedure we introduce right Insertion-of-Idempotents-Property (simply, right IIP) and right Idempotent-Reversible (simply, right IR) as generalizations of Abelian rings. It is proved that these two ring properties pass to power series rings and polynomial rings. It is also shown that ${\pi}$-regular rings are strongly ${\pi}$-regular when they are right IIP or right IR. Next the noncommutative right IR rings, right IIP rings, and Abelian rings of minimal order are completely determined up to isomorphism. These results lead to methods to construct such kinds of noncommutative rings appropriate for the situations occurred naturally in studying standard ring theoretic properties.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1177-1181
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• 2014

A 2D grid-like (4, 4)-connected topology coordination polymer, $[Co(BTA)_2(H_2O)_2]_n$ (1), where HBTA = 2-(1H-benzotriazol-1-yl)acetic acid, has been synthesized by hydrothermal method and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and surface photovoltage spectroscopy (SPS). X-ray diffraction analyses indicated that 1 displays octahedral metal centers with secondary building units (SBUs) [$Co(BTA)_2(H_2O)_2$] bridged by the $BTA^-$ ligands. In the crystal, the 2D supramolecular architecture is further supported by $O-H{\cdots}O$, $O-H{\cdots}N$, $C-H{\cdots}O$ hydrogen bonds and ${\pi}{\cdots}{\pi}$ stacking interactions. The SPS of polymer 1 indicates that there are positive response bands in the range of 300-600 nm showing photo-electric conversion properties. There are good relationships between SPS and UV-Vis spectra.

• 한국동물위생학회지
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• 제13권2호
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• pp.162-183
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• 1990

From 1988 to 1989, 8 strains of canine parvovirus-2 (CPV-2) were isolated from the fecal specimens from the dogs that were clinically diagnosed as canine parvoviral enteritis in the veterinary hospitals located in the regions of Taejon and Chungbuk province. Studios on biological and physicochemical properties for the isolates were carried out. The results obtained by experiments are summarized as follows. 1. Among 62 fecal samples collected from the dogs with enteric diseases, 24 (38.7%) showed the haemagglutinating activity against porcine erythrocyte, ranging from 16 to 16, 384 of HA titers. 2. When 8 fecal specimens with high HA titer over 1, 000 were inocultated into CRFX cells, intranuclear inclusion bodies were obseverd in all of eight specimens, of w)lick three specimens showed cytoplasmic inclusions concurrently with the intranuclear inclusion bodies. 3. In study on species-specificity of haemagglutinating activity of the isolates, TJ-89-1 and TJ-89-2, it was found that the isolates revealed the highest haemagglutinating activity with porcine erythrocytes, showing the relatively lower haemagglutination titers with the erythrocytes from cat and rabbit. None of erythrocytes from other animals reacted with the isolates. 4. By the cross-haemagglutination inhibition test of the Isolates with reference viruses and sera, the Isolates were evidently identified as the strains of canine parvovirus-2. 5. In Physicochemical property test, it was evident that the isolates were stable in, lipid solvent, pH and heat treatment at $56^{\circ}C$ for 30 min. and contain DNA genome. 6. When seven puppies were inoculated intraorally with the isolate at HA titer of 8, 192, all of the puppies showed the symptoms of anorexia, vomiting, diarrhea and died at the 5th to 10th days post inoculation(pi). The fecal samples from all of the puppies revealed significantly high HA titers afterward the 5th days pi. Body temperature and the number of total leucocytes were slightly increased at the early stage of infection. but extremely decreased at the stage of collapse. HI titers of the sera started to increase at the 2nd to 3rd days pi reaching 512 to 1, 024 at the 4th to 5th day pi.

• KIEE International Transactions on Electrophysics and Applications
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• 제11C권4호
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• pp.142-145
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• 2001

The residual DC phenomena in the in-plane switching(IPS)-liquid crystal display(LCD) by the voltage-transmittance (V-T) and capacitance-voltage (C-V) hysteresis method on rubbed polyimide (PI) surfaces were studied. We found that the residual DC voltage in the IPS-LCD was decreasing with the increasing concentration of cyano LCs. The residual DC voltage of the IPS-LCD can be improved by the high polarity of cyano LCs.

• 대한수학회지
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• 제54권1호
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• pp.177-191
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• 2017

In this note we consider the right unit-duo ring property on the powers of elements, and introduce the concept of weakly right unit-duo ring. We investigate first the properties of weakly right unit-duo rings which are useful to the study of related studies. We observe next various kinds of relations and examples of weakly right unit-duo rings which do roles in ring theory.

• 폴리머
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• 제37권5호
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• pp.618-624
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• 2013

Trimellitic anhydride chloride와 hydroquinone을 이용하여 hydroquinone bis(trimellitate anhydride)(HQ-TA)를 합성하였다. 합성된 HQ-TA와 6가지의 다양한 디아민들을 사용하여 전구체 polyamic acid(PAA)를 합성한 후, 열적-및 화학적-이미드화 반응을 거쳐 에스터 그룹을 가지는 폴리이미드(polyimide, PI) 필름을 합성하였다. PI 합성은 구조적으로 다양한 방향족 디아민을 사용하였다. 각 디아민 구조에 따른 유리전이온도($T_g$)는 167-$215^{\circ}C$를 보였고, 초기분해온도(${T_D}^i$)는 $364-451^{\circ}C$를 나타내었다. 가장 향상된 열팽창 계수(coefficient of thermal expansion, CTE)와 가스차단성은 TFB(3.23 $ppm/^{\circ}C$)와 4,4-ODA(< $10^{-2}cc/m^2/day$) 단량체를 각각 사용하였을 때 보였다. PI 필름의 투과도는 500 nm에서 65-89%를 보였으며, 노란색 정도를 나타내는 황색지수(yellow index, YI)는 3.01-69.52를 보였다.