• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.41-49
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• 2021

3D printing techniques have been recently adopted in the construction industry. It mainly utilizes additive manufacturing which is the fabrication process depositing successive layers of materials without any formworks. Conventional cementitious materials may not be directly applicable to 3D printing because 3D printable cementitious materials is required to satisfy such characteristics as pumpability, extrudability, and buildability in a fresh state. This study aimed to investigate rheological properties and required performances of 3D printable cementitious materials, by reviewing existing studies. Test methods and equipments, evaluation results and characteristics of mixture additives were compared. Based on reviews of existing studies, this study indicates that the viscosity is mainly relevant to the pumpability of 3D printable materials whereas the yield stress and thixotropy are important in securing buildability of the materials.

• Preventive Nutrition and Food Science
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• v.14 no.2
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• pp.148-155
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• 2009

The purpose of this study was to find new applications for Rubus coreanus and to produce new products. Jelly prepared with Rubus coreanus was studied and analyzed with regard to its composition, rheology and sensory evaluation. The technique of response surface methodology was used to analyze the results, which showed 16 experimental points including 2 replicates for Rubus coreanus juice, gelatin and sucrose. Rheological characteristics such as lightness, redness, yellowness and hardness, springness, chewiness and gumminess were shown to be significant, and these were mostly influenced by the content of Rubus coreanus juice. Significant sensory characteristics such as color, flavor, transparency, taste and the overall quality were also found to be greatly influenced by Rubus coreanus juice and gelatin in general. Based on the overlapping categories of factors that satisfied all sensory categories, the maximally optimized point was taken as the middle point. This value was determined to be 43.28 g of Rubus coreanus juice and 9.19 g of gelatin for every 140.00 g of sucrose.

• Journal of the Korean Society of Food Culture
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• v.27 no.6
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• pp.695-701
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• 2012

This study was conducted to improve the quality of Kongsulgidduk prepared with soyflour and sweeteners. The quality was affected by the type of sweeteners used (sugar, syrup, honey), as well as the amount used (5-20%). Rheological properties showed that when more sugar was added to Kongsulgidduk, the hardness, gumminess and brittleness were lower. In addition, more than 10% sugar led to a significant decrease in hardness, gumminess and brittleness. The addition of honey increased the hardness, but decreased cohesiveness and brittleness of Kongsulgidduk. When color was evaluated, the L-value and a-value decreased, but the b- value increased as sugar was added. The addition of honey resulted in a decreased L-value. Sensory evaluation revealed that the addition of sugar resulted in better overall quality. The color score was highest when 5% sugar was added, while the flavor, moisture and chewiness scores were best when 10% sugar was added. Sweetness and consistency were good when 20% sugar was added. Honey improved the color, flavor and chewiness of Kongsulgidduk; however, sugar produced the best moisture, consistency and overall scores.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.47-55
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• 1997

This study aims to know what the physicochemical properties and physical properties of the Korean traditional rice cake injulmi made from persimmon powder and glutinous rice(powder), and to come up with a standard recipe of it with the premixed powder of persimmon and glutinous rice. Cooked rice powder with 9 different levels of persimmon in cooling dough(75, 100 and 150${\mu}{\textrm}{m}$ power with each 20, 40, and 60%) was tested for rheological parameters, the rate of swelling, degree of gelatinization, sensory evaluation, and the observation of cross section used to electronmicroscope. 1. sensory evaluation conducted by 20 university students as panelists showed that mixed glutinous rice powder and persimmon powder lost their regular forms. increase in persimmon powder content increased a thin layer of starch granule, presumably due to sugar and fiber in the mixed persimmon powder granule. 3. In cooking the rice cake with 20~60% of persimmon, it showed 6.3 to 5.5 pH. 4. Quantitative description analysis conducted by 20 university student s panelists showed that sample that sample C was preferred among 9 samples. From these results, it was concluded that glutinous rice cake cooked with 20% of persimmon powder was quiet acceptable. Optimum cooking condition for the glutinous rice with persimmon powder rice cake was 30min of cooking time and 25$0^{\circ}C$ of cooking temperature with gas oven.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2151-2158
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• 2000

This paper presents vibration control performance of a passenger vehicle installed with the mixed-mode type ER engine mounts. The performance is evaluated via hardware-in-the-loop-simulation(HILS) method. As a first step, a dynamic model of a vehicle featuring the ER engine mounts is formulated by taking into account the engine excitation forces. A new type of the fuzzy skyhook controller is then established in order to control both engine and body vibrations. This is accomplished by adopting a weighting parameter between two performance criteria which is to be determined from the fuzzy algorithm. Vertical displacement and acceleration of the engine mount obtained from the HILS method are provided in the frequency domain. In addition, vibration control performance between the conventional hydraulic engine mount and the proposed engine mount is compared in the time and frequency domains.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.543-548
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• 2013

This paper presents a design of magnetorheological (MR) damper for control vibration of washing machine. This design is based on the requirements such as small dimensions with high damping force, and minimal consumed energy. The MR damper is designed using the shear mode of MR fluid, and Bingham plastic model is used for optimization process. In this design, a multi-coil design is adopted for damper to enhance damping force and reduce optimally structural parts. In optimization process, ADPL (Ansys Parametric Design Language) program is applied. Base on the optimal parameters, MR damper is manufactured and tested. In evaluation of MR damper, a modified sliding mode control is formulated and applied in both simulation and experiment. Results of experiment show that the MR damper satisfy the requirement of damping force for vibration control of washing machine.

• Journal of Pharmaceutical Investigation
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• v.39 no.3
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• pp.185-199
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• 2009

Using a strain-controlled rheometer [Advanced Rheometric Expansion System (ARES)], the steady shear flow properties and the dynamic viscoelastic properties of $Antiphlamine-S^{(R)}$ lotion have been measured at $20^{\circ}C$ (storage temperature) and $37^{\circ}C$ (body temperature). In this article, the temperature dependence of the linear viscoelastic behavior was firstly reported from the experimental data obtained from a temperature-sweep test. The steady shear flow behavior was secondly reported and then the effect of shear rate on this behavior was 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. The angular frequency dependence of the linear viscoelastic behavior was nextly explained and quantitatively predicted using a fractional derivative model. Finally, the strain amplitude dependence of the dynamic viscoelastic behavior was discussed in full to elucidate a nonlinear rheological behavior in large amplitude oscillatory shear flow fields. Main findings obtained from this study can be summarized as follows : (1) The linear viscoelastic behavior is almostly independent of temperature over a temperature range of $15{\sim}40^{circ}C$. (2) The steady shear viscosity is sharply decreased as an increase in shear rate, demonstrating a pronounced Non-Newtonian shear-thinning flow behavior. (3) The shear stress tends to approach a limiting constant value as a decrease in shear rate, exhibiting an existence of a yield stress. (4) The Herschel-Bulkley, Mizrahi-Berk and Heinz-Casson models are all applicable and have an equivalent validity to quantitatively describe the steady shear flow behavior of $Antiphlamine-S^{(R)}$ lotion whereas both the Bingham and Casson models do not give a good applicability. (5) In small amplitude oscillatory shear flow fields, the storage modulus is always greater than the loss modulus over an entire range of angular frequencies tested and both moduli show a slight dependence on angular frequency. This means that the linear viscoelastic behavior of $Antiphlamine-S^{(R)}$ lotion is dominated by an elastic nature rather than a viscous feature and that a gel-like structure is present in this system. (6) In large amplitude oscillatory shear flow fields, the storage modulus shows a nonlinear strain-thinning behavior at strain amplitude range larger than 10 % while the loss modulus exhibits a weak strain-overshoot behavior up to a strain amplitude of 50 % beyond which followed by a decrease in loss modulus with an increase in strain amplitude. (7) At sufficiently large strain amplitude range (${\gamma}_0$>100 %), the loss modulus is found to be greater than the storage modulus, indicating that a viscous property becomes superior to an elastic character in large shear deformations.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.97-104
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• 2016

OBJECTIVES : The objective of this research is to develop additives for the modification of Solvent DeAsphalting Residue (SDAR) to be used as pavement materials, and evaluate the performance of asphalt mixture manufactured using the SDAR modified by developed additives. METHODS : The SDAR generally consists of more asphaltenes and less oil components compared to the conventional asphalt binder, and hence, the chemical/physical properties of SDAR are different from that of conventional asphalt binder. In this research, the additives are developed using the low molecular oil-based plasticizer to improve the properties of SDAR. First, the chemical property of two SDARs is analyzed using SARA (saturate, aromatic, resin, and asphaltene) method. The physical/rheological properties of SDARs and SDARs containing additives are also evaluated based on PG-grade method and dynamic shear-modulus master curve. Second, various laboratory tests are conducted for the asphalt mixture manufactured using the SDAR modified with additives. The laboratory tests conducted in this study include the mix design, compactibility analysis, indirect tensile test for moisture susceptibility, dynamic modulus test for rheological property, wheel-tracking test for rutting performance, and direct tension fatigue test for cracking performance. RESULTS : The PG-grade of SDARs is higher than PG 76 in high temperature grades and immeasurable in low temperature grades. The dynamic shear modulus of SDARs is much higher than that of conventional asphalt, but the modified SDARs with additives show similar modulus compared to that of conventional asphalt. The moisture susceptibility of asphalt mixture with modified SDARs is good if, the anti-stripping agent is included. The performance (dynamic modulus, rutting resistance, and fatigue resistance) of asphalt mixture with modified SDARs is comparable to that of conventional asphalt mixture when appropriate amount of additives is added. CONCLUSIONS : The saturate component of SDARs is much less than that of conventional asphalt, and hence, it is too hard and brittle to be used as pavement materials. However, the modified SDARs with developed additives show comparable or better rheological/physical properties compared to that of conventional asphalt depending on the type of SDAR and the amount of additives used.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.505-512
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• 2016

Even though high performance concrete was developed according to the trend of bigger and higher of reinforced concrete building, the rheological evaluations such as viscosity, yield stress are not enough to use as input data to accomplish the numerical analysis for the construction design. So there are many problems in the harden concrete such as poor compaction, rock pocket and crack, etc. in the field. In this study, consistency curves were measured by the viscometer as hydration reaction time passed. At the same time the slump flow test and Vicat setting test were carried out for comparing with the results of rheological properties. The fluidity of the W/B 30% decreased as the increase of replacement ratio of blast furnace slag. But in case of W/B 40%, the replacement ration did not significantly influenced to the slump flow value with the passage of hydration time. By the replacement of blast furnace slag to cement, initial setting was delayed and the time gap between initial and final setting became shorten. Through the regression analysis using Bingham model, there are a sudden changes of viscosity and yield stress around initial setting in case of low W/B 30%. The increase of workability by the change of free water in cement paste was offset by the coating effect of impermeable layer in case of W/B 40%.

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.278-283
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• 2009

This study was carried out to evaluate the quality characteristics of white pan breads containing 0.5% of gums, including HPMC, MC and SA. Moisture content, water activity, cooling loss, bread volume, rheological, and sensory evaluations were performed to examine the bread quality characteristics. Moisture content and water activity were highest in the bread with added HPMC. HPMC showed the smallest cooling loss among the breads compared to the other added gums. The bread with added SA had the thelargest volume at $2,560{\pm}24$ mL. In terms of rheological properties, the hardness of the bread containing HPMC was lowest and the springness of the bread with added SA was the highest. In sensory evaluations, the bread containing HPMC was evaluated as the most preferred product by acquiring the highest scores in internal and external evaluations. Consequently, the bread containing 0.5% SA showed better volume and springiness values. However, the bread containing 0.5% HPMC showed greater moisture content, greater water activity, lower cooling loss, and better sensory evaluation scores. Based on the overall results, HPMC was considered to be the most effective hydrocolloid to increase bread quality.