• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.611-614
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• 2003

The rheological properties of exopolysaccharide, p-KG03, produced by marine microalgae Gyrodinium impudicum strain KG03 had been studied. The intrinsic viscosity of this p-KG03 was calculated to 65.22 and 50.75 $d{\ell}/g$ using Huggins and Kramer equations (xanthan gum 24.41 and 24.03). Aqueous dispersions at p-KG03 concentrations ranging from 0.1 to 1.0 % (w/w) showed marked shear-thinning properties as Power-Law behavior. In aqueous dispersions of p-KG03 1.0 %, consistency index (K) and flow behavior index (n) were 2,172 and 0.52. The apparent viscosity and the influence of shear rate on different conditions as p-KG03 concentrations, pH, NaCl, $CaCl_2$ and temperature in aqueous solutions were measured. And p-KG03 had mixed with aqueous solutions of xanthan gum and gellan gum, and invested the change of mixed aqueous solution behavior.

• Polymer(Korea)
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• v.26 no.3
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• pp.353-359
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• 2002

High intensity ultrasound has been applied to a series of poly(ethylene oxide) (PEO)/water systems having different molecular weights of PEO. Major interest was focused on the effect of ultrasonic wane on the melt viscosity chemical structure and thermal properties of PEO. The expected role of ultrasound used in this study was to generate macroradicals of PEO chains by the formation and subsequent collapse of bubbles. It was found that the melt viscosity and chemical structure of PEO change significantly depending on the sonication time. For the prolonged sonication, PEO chains were significantly degraded and new end groups were formed by the interplay of various radical species. When the molecular weight of PEO was relatively higher, the crystallization rate was decreased and the intensity of the melting peak was reduced.

• Journal of the Korean Wood Science and Technology
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• v.15 no.4
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• pp.64-68
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• 1987

To develope the utilities of the chestnut bur, which is wasted after harvesting chestnut in farmhouses, the feasibilities of adhesion(urea resin) extenders of the powder for plywood were examined. These experiments were implemented on experimental scale at Forestry Research Institute(Seoul) and on a plywood mill scale at Eugon Industrial Co LTD(Inchon) for more reliable data. In this paper, it was proved that the chestnut bur powder caused to rise the glue viscosity but the chaff powder to down reversely. The most effective mixing ratio were wheat flour 5kg, chaff powder: 5kg and chestnut bur powder. 5kg per 100kg of urea resin. At this condition, the viscosity were most appropriate (1,320 2,230 cps) for glue spreading operations, and the dry shear strengthes were most adequate(10.7-13.2kg/$cm^2$), wood failure ratio 82-88%). The chestnut bur powder, can be utilized for plywood adhesion extenders without any change of present process lines in plywwod mills.

• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.109-115
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• 2004

Comparisons in shear behaviour are made between aqueous suspensions of a laterite ore and aqueous suspensions of pure goethite ($\alpha$-FeOOH), following prior papers in which the rheologies of the two mineral suspensions were characterized individually. Drawing comparisons is appropriate because the ore sample was about 65% goethite and it was originally thought that the pure goethite might serve as a model of the more complex laterite. Viscosity measurements of the two suspensions show that, at the same solids fraction, the goethite suspensions were more viscous by an order of magnitude, even though the goethite particles had much smaller aspect ratios. Similarly, yield stresses for the goethite suspensions were at least an order of magnitude higher. The most significant difference was in transient behaviour. Time-dependent effects were investigated by subjecting a fluid to a step change or a ramp sequence in shear rate, and measuring the resulting shear stress over time. In most cases, transient behaviour could not be detected in the goethite suspensions, whereas stresses in the laterite suspensions relaxed over periods of order 10 seconds. The disparate results indicate that a goethite suspension is a poor model of a laterite slurry.

• The Korean Journal of Food And Nutrition
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• v.13 no.1
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• pp.21-27
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• 2000

In order to investigate the changes of rice qualities during 4 years storage of paddy in warehouse of normal temperature condition. As storage period go by, head ratio was deduced and broken rice was increased according as a change of temperature during the long term storage. A color of rice was became more dark gray than that of entering time as L value was decreased from 64.07 to 61.62 a 4 years late. As a results of studies on the cooking quality of milled rice, water uptake ratio and expanded volume were increased in proporation to storage period, wherease total solids and iodine blue value were decreased. In the characteristic of texture of cooked rice, viscosity/hardness ratio(-H/H) had a decreasing tendency, while adhesiveness and cohesiveness increased with increased storage time. The qualities of cooked milled rice studied were sensory attributies of odor, taste, stickiness and appearance which were evaluvated by multiple comparsion method. The sensory results showed that all of descriptions were deterirated with a increased storage period. The taste and stickiness were changed from good score to bad score a 2 years later.

• Korean journal of food and cookery science
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• v.22 no.2 s.92
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• pp.111-121
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• 2006

The aim of this study was to investigate the possibility of producing goods evaluating the preservation of DSG, PSG, DST and PST, all of which were the most preferred according to the results of sensory evaluation of some sauces made of Demi-glace sauce and a Teriyaki-applied sauce. The pH of normal Demi-glace sauce, at 5.2, was the highest among these sauces. The Teriyaki-applied Demi-glace sauce was the second with pH 5.12 DSG was the lowest. The pH didn't change significantly according to preservation. However, the degree of PSG's pH was lowered by the time period of preservation. DGST didn't changed a lot apart from being a bit morewatery (12.40) after three-week storage. It seemed that the viscosity of the normal sauces, checked after 10 sec, decreased. At 20 sec there were no differences among these sauces. After making 10 applied sauces and evaluating them, DSG, PSG, DST and PST gained the highest preference and the application of Teriyaki sauce was evaluated favorably. According to the preservation test. the sensory evaluation didn't seem to decrease within 2 weeks which demonstrated that the other physicochemical products were unaffected. Therefore, an improvement following more than two-week preservation is expected in t case of rigid store regulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.288-294
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• 1990

Two pure fuel oils(#1 oil, #6 oil), theree pure alcohols (methanol, ethanol, propanol) were tested for the fuel characteristics such as miscibility (that established which pure fuels and fuel mixtures could be fired in the boiler), flash point, viscosity. Specific target of the study besides the oil/alcohols or oil/alcohol mixture without any modification and with safety. #1 oil could be mixed without any problems at all concentrations with two of the alcohols; these were the ethanol and propanol. However, miscibility of #6 oil with any alcohols and #1 oil with methanol was not possible and very limited in this study. The measurements of flash point and viscosity for the mixtures were done for the comparisons with the pure fuels. There was a marked change of flame shape and flame luminosity as the alcohol content of the mixtures was increased. The mixture flame shortened and became non-luminous compared with a pure fuel oil flame.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.132-136
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• 2011

수제는 유수에 의한 하안 침식을 방지하기 위한 목적의 수공구조물이다. 최근에는 하천복원 및 생태계복원에 대한 관심이 증가되면서, 하안 침식 방지뿐만 아니라 수제에 의한 흐름분리 및 재순환영역의 생태 서식처 제공에 대한 역할이 부각되고 있다. 따라서 수제 설계 시, 수제 설치에 따른 수리특성 변화를 미리 파악하는 것이 필요하지만, 수제 간격, 설치 방향, 수제 높이, 수제 길이, 하도 특성 및 접근 유수 특성 등 다양한 인자에 의해 수리특성 변화를 예측하기란 쉽지 않으며, 비용과 시 공간 측면에서 물리 모형을 이용한 접근법도 용이하지 못하다. 따라서 본 연구에서는 2차원 수치모형을 이용하여 수제 설치에 따른 흐름특성 변화를 모의하고, 모형의 적용성을 판별하고자 하였다. 지배 방정식은 기본적으로 천수방정식을 적용하게 되는데, 수제 주변 흐름 특성은 난류에 의한 횡방향 확산이 중요한 인자로작용하게 된다. 상수 와점성(constant eddy viscosity) 모형, 포물선형 와점성 (parabolic eddy viscosity) 모형을통해 개발 모형의예측 결과와 실험수로 결과를 비교하였다. 수제하류의 재순환영역의 길이가 실험수로의 결과에 비해서 5~6 배까지 확대된 결과를 나타내고 있어, 만족할 만한 결과를 현재까지 얻지 못하였다. 횡방향 확산이 중요한 만큼 k-$\varepsilon$ 모형 등 다양한 난류 모형의 적용이 고려되어질 필요가 있으며, 또한 1차원 요소가 아닌 2차원 요소의 적용을 고려할 필요도 있다.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.5
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• pp.23-32
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• 2015

In this study, chemical and physical changes of dissolving pulps which have similar viscosity by dry milling and fractionation were investigated. We used two types of dissolving pulp made from wood and cotton linter fiber, respectively. Dry milling was executed by knife cutter and pulp powders were fractionated by sieve shaker into 4 grades. We analyzed fiber properties, crystallinity index, viscosity, molecular weight of pulp sheet and powders. It was found that poly-dispersity index of cotton linter pulp was smaller than that of wood pulp, meaning that cotton pulp has more narrow molecular weight distribution. It was assumed that these were related to exposure times to chemical treatment which cut cellulose chains not evenly. At least 4 times of chemical treatments for wood pulp were executed and only two times of chemical treatments for cotton linter pulp were done. After dry milling average molecular weight and crystallinity index of cotton linter pulp powders were reduced and these were related to fines content and shape of pulp powders.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.588-594
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• 1992

Polyisocyanurate has been obtained from toluene diisocyanate(TDI) in the presence of potassium octoate catalyst and the effects of water and butanol in solvent were studied for the determination of the change of viscosity, the reaction time (length of time required for 5 poise of viscosity of product), molecular dispersity of product, and TDI conversion. When butyl acetate contains 0.1% of water by weight, uretidione was formed and a higher conversion was obtained at the condition. The uretidione was not formed by adding butanol to the solvent. At a higher concentration of butanol, a higher TDI conversion and a wider molecular dispersity were obtained.