• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.137-148
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• 2007

Using a strain-controlled rheometer [Rheometrics Dynamic Analyzer (RDA II)], the steady shear flow properties of a semi-solid ointment base (vaseline) have been measured over a wide range of shear rates at temperature range of $25{\sim}60^{\circ}C$. In this article, the steady shear flow properties (shear stress, steady shear viscosity and yield stress) were reported from the experimentally obtained data and the effects of shear rate as well as temperature on these properties were discussed in detail. In addition, several inelastic-viscoplastic flow models including a yield stress parameter were employed to make a quantitative evaluation of the steady shear flow behavior, and then the applicability of these models was examined by calculating the various material parameters (yield stress, consistency index and flow behavior index). Main findings obtained from this study can be summarized as follows : (1) At temperature range lower than $40^{\circ}C$, vaseline is regarded as a viscoplastic material having a finite magnitude of yield stress and its flow behavior beyond a yield stress shows a shear-thinning (or pseudo-plastic) feature, indicating a decrease in steady shear viscosity as an increase in shear rate. At this temperature range, the flow curve of vaseline has two inflection points and the first inflection point occurring at relatively lower shear rate corresponds to a static yield stress. The static yield stress of vaseline is decreased with increasing temperature and takes place at a lower shear rate, due to a progressive breakdown of three dimensional network structure. (2) At temperature range higher than $45^{\circ}C$, vaseline becomes a viscous liquid with no yield stress and its flow character exhibits a Newtonian behavior, demonstrating a constant steady shear viscosity regardless of an increase in shear rate. With increasing temperature, vaseline begins to show a Newtonian behavior at a lower shear rate range, indicating that the microcrystalline structure is completely destroyed due to a synergic effect of high temperature and shear deformation. (3) Over a whole range of temperatures tested, the Herschel-Bulkley, Mizrahi-Berk, and Heinz-Casson models are all applicable and have an almostly equivalent ability to quantitatively describe the steady shear flow behavior of vaseline, whereas the Bingham, Casson,and Vocadlo models do not give a good ability.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.564-569
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• 2008

Strain hardening behavior during hydroforming has been experimentally investigated. The variation of flow stress was used as an index of strain hardening during respective processes and the flow stress was estimated from the correlationship between flow stress and effective strain. The local hardness after hydroformig was also predicted by effective strain. By using the inter-relationships between hardness-flow stress-effective strain at variable pre-strains, the strain hardening behavior during hydroforming has been successfully analyzed. The comparison of predicted hardness with measured hardness confirmed that the methodology used in this study was feasible and the strain hardening behavior can be quantitatively estimated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2234-2243
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• 2013

The purpose of this study was to measure using a six-step solution for taste recognition threshold and using a Wet-Test for salivary flow amount of the adults who reside in Daegu area and are more than their 40's old to find out the relationship between DMFT index and OHIP-14. The study result revealed that the practice of oral health gave an effect to taste recognition threshold, dietary habit gave an effect to salivary flow amount, and sweet and sour taste of taste recognition threshold and salivary flow amount gave effects to the DMFT index. Therefore, it was found that the person with good practice of oral health and dietary habit had good taste, salivary flow amount and DMFT index. According to this result, it is necessary to increase the practice of oral health, increase the sensitivity to taste recognition threshold, improve dietary habit, increase salivary flow amount and decrease DMFT index in order to improve OHIP-14. Dietary habit education has been performed without the evaluation on the individual's level of taste recognition threshold. Therefore, it is necessary to develop the education program to measure and notify the taste recognition threshold in the oral health education so that individual can adjust it by himself.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.241-242
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• 2016

Recent abnormal climate change induces localized heavy rainfall and extreme disasters such as debris flow near urban area. Thus many researches have been conducted to estimate and prevent, especially in focus of physical behavior of debris flow. Even though it is hardly to consider overall related parameters to estimate the extent and degree of directly or indirectly damages due to debris flow. Those analytic restraint would be caused by the diversity and complexity of regional topographic and hydrodynamic characteristics of debris flow inside. We have utilized the Bayesian method to compensate the uncertainty due to the complex characteristics of it after analyzing the numerical results from FLO-2D and field measurement data. Revised values by field measurements will enhance the numerical results and the missing parameters during numerical simulation will be supplemented with this methodology. As a final outcome in this study, the risk index of debris flow damage will be suggested to provide quantitative estimation in terms of hazard protection including the impact on buildings, especially in inner and outer of urban area.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.808-811
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• 2001

The rheological properties of exopolysaccharide(EPS-R) produced by marine bacteria Hahella chjuensis KCTC 2395 was investigated. EPS-R solution showed a characteristic non-Newtonian behavior fluid properties. In aqueose dispersions of EPS-R 1%, consistency index(K) and flow behavior index(n) were 1,410 cp and 0.73. EPS-R solution was pseudoplastic fluid by power-low model. Rheological propertie of EPS-R was found to be influenced by the concentration of salt, pH, temperature and ionic compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.554-558
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• 1999

Flow properties of traditional kochujang at various fermentation times(0~12 weeks) were determined with rotational cylindrical(RC) and serrated plate plate(PP) viscometer. Magnitudes of consistency index(K) of power law model and Cassson parameters(yield stress and viscosity) measured by PP viscometer were higher than those using RC viscometer. All kochujang samples during fermentation were much shear thinning with values of flow behavior index(n) as low as 0.2~0.34. K value and Casson yield stress measured by PP viscometer had good correlations(r=0.94; r=0.91) with fermentation time. No significant changes in flow model parameters measured by RC viscometer were observed for kochu jang during fermentation. Magnitudes of flow model parameters measured by PP viscometer more closely correlated with fermantation times of kochujang than did RC viscometer.

• Journal of Advanced Marine Engineering and Technology
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• v.6 no.2
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• pp.21-41
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• 1982

Viscosity, especially characteristic among various properties of visco-elastic fluids such as high polymer solutions, is affected mainly by temperature and concentration. Hence, it is important for fluid engineering to express, by some equations, how the fluid characteristics vary with the change of temperature and concentration and to analyze them to obtain consistent viscous characteristics. High polymer solutions, synthetic products of modern chemical industry, suggest many interesting investigations because they are typical visco-elastic materials. Experimentation was made to derive some useful fluid characteristic equations of SEPARAN-NP10 (polyacylamide) expressed by n (flow behavior index) and K' (consistency index) when it is given temperature and concentration variation. To measure viscosity, capillary viscometer was adopted and the range of experimentation is 0-2,000 P.P.M. in concentration and 15-55 .deg.C in temperature. The experimental results are summarized as follows: The flow behavior index n 1) has nearly constant results irrespective of temperature variation at same conentration and the results are shown in (Table. 4-4-3) 2) has following equation, regardless of temperature, for the variation of concentration. n=-1.0765*10$^{-4}$ P+0.9915 (P:P.P.M.) The consistency index K' 1) has different results for the variation of temperature at same concentration and the results are given in (Table.4-7-2) 2) has following equation for the variation of concentration at same temperature. log 10$^{4}$K' =6.4785*10$^{-4}$ P-1.0529 (P:P.P.M)

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.136-145
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• 2004

In companion paper, the composition and structure of the traffic environment is derived. Rules to regulate agent behaviors and the frameworks to communicate between the agents are proposed. In this paper, the model of a driver agent which controls a vehicle agent is constructed. The driver agent is capable of having different driving styles. That is, each driver agent has individual behavior settings of the yielding index and the passing index. The yielding index can be defined as how often the agent yields in case of lane changes, and the passing index can be defined as how often the agent passes ahead. According to these indices, the agents overtake or make their lanes for other vehicles. Similarly, the vehicle agents can have various vehicle dynamic models. According to their dynamic characteristics, the vehicle agent shows its own behavior. The vehicle model of the vehicle agent contains the nonlinear subcomponents of engine, torque converter, automatic transmission, and wheels. The simulation has proceeded for an interrupted flow model. The result has shown that it is possible to express the characteristics of each vehicle and its driver in a traffic flow, and that the change of the traffic state is closely related with the distance and the signal delay between intersections. The system developed in this paper shows the effectiveness and the practical usefulness of the traffic simulation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.2
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• pp.181-185
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• 1993

The effects of concentrations (6~9%), heating temperatures (80, 85, 90 and 95$^{\circ}C$) and heating methods (continuous, method A and instantaneous, method B) on the flow properties of cowpea flour (air-dried sediment) at 6$0^{\circ}C$ were studied. The gelatinized cowpea flour dispersions by method B had higher values of yield stress and consistency index but lower value of flow behavior index compared to those values of method A. The log values of consistency index were positively correlated with the concentration and heating temperature for both methods. The rate of increase in the consistency index value by method B at the same concentration was greater in all heating temperatures than that by method A.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.145-154
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• 2006

In the companion paper, the composition and structure of the MATDYMO (Multi-Agent for Traffic Simulation with Vehicle Dynamic Model) were proposed. MATDYMO consists of the road management system, the vehicle motion control system, the driver management system, and the integration control system. Among these systems, the road management system and the integration control system were discussed In the companion paper. In this paper, the vehicle motion control system and the driver management system are discussed. The driver management system constructs the driver agent capable of having different driving styles ranging from slow and careful driving to fast and aggressive driving through the yielding index and passing index. According to these indices, the agents pass or yield their lane for other vehicles; the driver management system constructs the vehicle agents capable of representing the physical vehicle itself. A vehicle agent shows its behavior according to its dynamic characteristics. The vehicle agent contains the nonlinear subcomponents of engine, torque converter, automatic transmission, and wheels. The simulation is conducted for an interrupted flow model and its results are verified by comparison with the results from a commercial software, TRANSYT-7F. The interrupted flow model simulation is implemented for three cases. The first case analyzes the agents' behaviors in the interrupted flow model and it confirms that the agent's behavior could characterize the diversity of human behavior and vehicle well through every rule and communication frameworks. The second case analyzes the traffic signals changed at different intervals and as the acceleration rate changed. The third case analyzes the effects of the traffic signals and traffic volume. The results of these analyses showed that the change of the traffic state was closely related with the vehicle acceleration rate, traffic volume, and the traffic signal interval between intersections. These simulations confirmed that MATDYMO can represent the real traffic condition of the interrupted flow model. At the current stage of development, MATDYMO shows great promise and has significant implications on future traffic state forecasting research.