• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.315-321
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• 1988

The input-output relation for nonlinear systems can e explicitly represented by the volterra functional series and it is characterized by the Volterra kernels. A block diagram reduction method is proposed to determine the Volterra kernels for nonlinear differential equations and is compared with the direct substitution techniques. The former method can significantly reduce the computational complexity. A degree of nonlinearity is defined and analyzed for the analysis of nonlinear systems.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.299-300
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• 2003

본 연구자들은 이산화탄소($CO_2$)에 의한 셀룰로오스 카보네이트의 제조 및 재생 셀룰로오스 섬유 제조에 대한 몇몇 기초 연구성과를 발표한 바 있다[1, 2]. 이번 연구에서는 이산화탄소와의 반응을 통해 제조된 셀룰로오스 카보네이트 유도체의 치환도 변화에 따른 용해성을 평가하고 상그림표를 작성하였다. (중략)

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.350-353
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• 2001

As different service classifications for existing and new business data services, it is hard to gather necessary data for the service providers to set their strategies and regulations are also applied asymmetrically to each service provider. Therefore an appropriate market classification is required for the business data services. The Hendry model is selected in this paper to analyze substitution degree among services and then Hendry model is applied to competition among four business data services. As a result, it is shown that these services compete directly and future market shares of services are forecasted and positioning strategy for new services is considered.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.4 s.107
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• pp.49-59
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• 2004

This study was carried out to obtain the basic data for producing higher functional coating agents for pulp mold by evaluating various kinds of starch derivatives. At that time, four kinds of starch derivatives were manufactured for making coating agents respectively. Physical properties of coated paperboards were tested. Conclusions obtained from this results were as follows. The water and oil resistance of hydroxypropylated, cyanoethylated and carboxymethy­lated starch were high when degree of molar substitution(DS) of propylene oxide, acrylonitrile and sodium monochloroacetate were 0.18, 0.07 and 0.009, respectively. Also, the those of crosslinked starch were high when degree of crosslinking of epichlorohydrin was 0.02. Consequently, $8\%$ solution of carboxymethylated starch made with DS 0.009 of monochloroacetate was the best among coating agents from starch derivatives men­tioned above.

• Journal of the Korean Wood Science and Technology
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• v.24 no.4
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• pp.82-86
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• 1996

This study was performed to elucidate the effect of degree of substitution and degree of polymerization of CMC on the rheological characteristics of coating color which is consisted of calcium carbonate as pigment. The results were as follows: 1. It appeared that DP of CMC rather DS has an effect on the low shear viscosity of coating color. 2. According as shear rate increased, the effect of DP and DS on high shear viscosity of coating color decreased. 3. According to increasing DS and DP, the water retention of coating color increased.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.1
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• pp.113-120
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• 1994

The Purpose of this study was to improve the moisture related properties of viscose rayon fibers. Viscose rayon filament yarns were partially etherified to make CMC fibers. CMC fibers were converted to the sodium, calcium, and ferric salt forms by an ion exchange method. The property changes of ion exchanged CMC fibers were examined. Cation contents of fibers were varied depending on the degree of substitution of CMC fibers. The strength of Na, Ca, Fe-CMC was higher than H-CMC owing to the plasticization by moisture sorption and the crosslinking by cations. The moisture regain was increased by carboxymethylation and that of Fe-CMC showed the highest value. The degree of swelling determined by the water retention value was observed to be Na-CMC > Ca-CMC > H-CMC > Fe-CMC. The solution retention value was decreased in the order . Ca-CMC > Na-CMC > H-CMC > Fe-CMC.

• Computers and Concrete
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• v.7 no.1
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• pp.17-38
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• 2010

This research aimed to investigate the influence of high-volume mineral admixtures (MAs), i.e., fly ash and slag, on the hydration characteristics and microstructures of cement pastes. Degree of cement hydration was quantified by the loss-on-ignition technique and degree of pozzolanic reaction was determined by a selective dissolution method. The influence of MAs on the pore structure of paste was measured by mercury intrusion porosimetry. The results showed that the hydration properties of the blended pastes were a function of water to binder ratio, cement replacement level by MAs, and curing age. Pastes containing fly ash exhibited strongly reduced early strength, especially for mix with 45% fly ash. Moreover, at a similar cement replacement level, slag incorporated cement paste showed higher degrees of cement hydration and pozzolanic reaction than that of fly ash incorporated cement paste. Thus, the present study demonstrates that high substitution rates of slag for cement result in better effects on the short- and long-term hydration properties of cement pastes.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.1010-1013
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• 1997

Nucleophilic substitution reactions of (Z)-phenylethyl (X)-benzenesulfonates with (Y)-pyridines were investigated in acetonitrile at 60 ℃ under respective pressures. The magnitudes of the Hammett reaction constants, ρX, ρY and ρZ indicate that a stronger nucleophile leads to a greater degree of bond formation of C-N and a better leaving group is accompanied by a less degree of bond breaking. The magnitude of correlation interaction term, ρij can be used to determine the structure of the transition state (TS) for the SN reaction. As the pressure is increased, the Hammett reaction constants, ρX and |ρY|, are decreased, but correlation interaction coefficient, ρXZ and |ρYZ|, are increased. The results indicate that the reaction of (Z)-phenylethyl (X)-benzenesulfonates with (Y)-pyridines probably moves from a dissociative SN2 to early-type concerted SN2 mechanism by increasing pressure. This result shows that the correlation interaction term ρij can be useful tool to determine the structure of TS, and also the sign of the product ρXZ·ρYZ can be predict the movement of the TS.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.329-336
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• 1998

Sandmats are used to dissipate trapped water rapidly from the embankment built on marine soft ground. At present, however, it becomes difficult to obtain qualified sands since natural resources such as river sand are to exhausted. Also, low permeability of sand may cause low degree of consolidation and instability of embankment. In this study, design and construction methods was discussed. Drainage capacities of prefabricated horizontal drains which were installed in highway construction site are investigated in order to find possible substitution for river sands as drainage materials. On the basis of measurement data at the construction site, it was concluded that use of the prefabricated horizontal drains shows satisfactory drainage capacity without instability of embankment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.1048-1052
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• 2011

This study examined the flow properties, paste clarity, freeze-thaw stability and gel strength of acetylated sweet potato starch (ASPS) pastes and gels as a function of degree of substitution (DS). ASPS showed high shear-thinning flow behaviors with high Casson yield stress ($\sigma_{oc}$). Consistency index (K), apparent viscosity ($\eta_{a,100}$) and $\sigma_{oc}$ values of ASPS increased with an increase in DS. In the temperature range of $25{\sim}70^{\circ}C$, ASPS followed an Arrhenius temperature relationship. The activation energies (Ea=13.2~14.3 kJ/mol) of the ASPS samples were much lower than that (18.1 kJ/mol) of the native sweet potato starch (SPS). ASPS gels showed better freeze-thaw stability with a significant decrease in syneresis (%) compared to SPS gel. The gel strength values of ASPS were much lower than that of SPS, and significantly decreased with an increase in DS. The clarity of native SPS paste increased after acetylation.