• Macromolecular Research
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• v.15 no.5
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• pp.418-423
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• 2007

A methacrylate copolymer based on isobornyl methacrylate (IBMA) and methyl methacrylate (MMA) was synthesized in an aqueous suspension via free-radical polymerization. The potential of this copolymer as a heat-resistant optical polymer is also discussed. 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanoate and n-octyl mercaptan were used as the initiator and chain transfer agents, respectively. The effect of IBMA on the properties of the copolymer was investigated. The composition of the copolymer was analyzed using $^1H-NMR$, and the heat resistance by measuring the glass transition temperature, which exhibited a linear dependency on the IBMA content in the copolymer. Variation of the chain transfer content used in the synthesis step was effective for the optimization of the copolymer for practical use.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2253-2258
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• 2008

To design micro flow sensor varying depending on temperature of driving heater in the detector of Oxide semiconductor, Markov chain MCM(MCMCM), which is a kind of stochastic and microscopic method, was introduced. The formulation for the thermal transfer equation based on the FDM to obtain the MCMCM solution was performed and investigated, in steady state case. MCMCM simulation was successfully applied, so that its application can be expanded to a three-dimensional model with inhomogeneous material and complicated boundary.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.972-976
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• 1995

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

• Bulletin of the Korean Chemical Society
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• v.9 no.4
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• pp.248-251
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• 1988

Mechanism of electrochemical polymerization of pyrrole (Py) on a Pt electrode in acidic aqueous solutions was studied by means of potentiostatic measurements, cyclic voltammetry and chronopotentiometry. Pyrrole molecule appeared to be initially oxidized via two-electron transfer step to produce oxidized pyrrole ion ($Py^+$), which was coupled with a non-oxidized pyrrole to yield a dimerized species, Py-Py. The Py-Py thus formed was further oxidized again via two-electron transfer step, which was followed by coupling with non-oxidized monomer and by concomitant expulsion of a $H^+$. Then the latter chain extension process was repeated. The chain extension and polypyrrole oxidation reactions occurred competitively.

• Journal of the Korean Operations Research and Management Science Society
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• v.35 no.4
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• pp.17-31
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• 2010

This study investigates two-stage return policy and recycling issues in an e-marketplace supply chain consisting of consumers, a retailer and a manufacturer. The manufacturer, a focal company in the e-marketplace supply chain, considers the recycling of commercial returns so offers the retailer a buy-back contract of which transfer payment consists of a wholesale price and a buy-back price. Then, under the given contract offer, the retailer determines a selling price and a return policy to control consumers' demand and return requests. We consider the retailer's opportunistic behavior and supply chain coordination issues based on the principal-agent paradigm. We compare the first-best and second-best optima and conduct comparative static analyses to evaluate the performance results of the buy-back contract and provide important managerial implications.

• Bulletin of the Korean Chemical Society
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• v.17 no.4
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• pp.376-379
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• 1996

The bulk photopolymerization of methacrylic acid (MA) with phenylsilane was performed to produce poly(MA)s containing phenylsilyl moiety presumably as an end group. It was found that while the polymerization yields and intrinsic viscosities decreased, the TGA residue yields and the relative intensities of SiH IR stretching bands increased with increasing molar ratio of phenylsilane over MA. The phenylsilane seemed to significantly influence on the photopolymerization as both chain initiation and chain transfer agents.

• Journal of Information Technology Services
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• v.20 no.3
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• pp.87-101
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• 2021

Since the introduction of block chain technology, its potential use in financial service area have been increasing, and financial firms are seeking ways to take advantage of the benefits of it. The purpose of this study is to present an approach to prioritize block chain-based services for bank. Toward this, we picked out potential financial services through focus group interview and derived the criteria that can be used in evaluating the priorities of block chain-based banking services in the same way. Then, we propose an analytic hierarchy process model to help decision makers prioritize the banking services while considering multiple criteria of technology issues, governmental regulations in the financial industry, cost, managerial issues, customers' needs, and the business opportunity for the bank. By using the analytic hierarchy process model, we can estimate the weighting coefficients to be assigned to each criteria and determine the order of priority in determining the best block chain-based service for the case study bank. The results show that banking login authentication would be forefront service, followed by money transfer, document notarization, and trade financing service in the order, and the trade financing could be most important service in terms of the business profitability for the bank in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.1
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• pp.50-63
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• 2017

While transit is inconvenient, it is also inevitable for the efficient public transportation. Reducing the number of transfers as much as possible is most important in providing the convenience of public transportation and facilitating the public transportation. As for the public transportation card data, 61,986 items on weekdays and 69,100 items on weekends were collected. Pattern analysis and traffic influence factors were analyzed using traffic data card. Trip chain results revealed that people have more transit transfers for shopping and leasure than commuting purposes on weekends and that commuting distance and time increase by 10 km and 9.9 minutes, respectively. Besides, results of the structural equation model showed that factor 1(total travel time, total travel distance), factor 2(number of people getting on and off), factor 3(transit time), and factor 4(number of bus connections, number of operations) were found to have significant effects on the number of transfers.

• Polymer(Korea)
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• v.26 no.6
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• pp.759-766
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• 2002

Regular, spherical and isotropic open-microcellular foams having low density were prepared by the high internal phase emulsion (HIPE) polymerization mainly composed of styrene monomer and water The effects of Polymerization conditions. such as the content of water, divinylbenzene as a crosslinking agent and dodecane as a chain transfer agent, were investigated based on the tell size and foam properties. The microstructural morphology was observed using scanning electron microscopy (SEM) and the compression modulus of the foam was evaluated using compression test. The dropwise feeding of the aqueous phase into the oil phase was more effective than the batch feeding in producing the uniform and stable foam. Agitation speed and surfactant strongly influenced on the cell size and the window size between water droplets. Introduction of chain transfer agent increased the cell size, whereas it decreased the window size. Compression modulus increased with the crosslinking agent, but decreased with the chain transfer agent.

• Polymer(Korea)
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• v.32 no.6
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• pp.566-572
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• 2008

Polyethylene has been prepared via metallocene catalysts [(TMDS)$Cp_2$]$ZrCl_2$, 1, and [$(n-Bu)_2Cp_2$]$ZrCl_2$, 2, in the presence of hydrogen as a chain transfer reagent. Increase of hydrogen flow to the polymerization reactor resulted in the drop of catalytic activity, reduction of molecular weight of polyethylene, getting narrow of molecular weight distribution of polyethylene, and melting point of the polyethylene wax. It should be noticed that it was possible to control molecular weight down to 1500 and melting temperature to 60 $^\circ$C of polyethylene wax using the catalyst 1 that has been developed by authors as well as the catalyst 2 from Exxon.