• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.6
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• pp.730-738
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• 2017

In this study, we investigated the physicochemical properties of coffee brews according to coffee bean grinding grade. We also examined the effect of grinding grade on amounts of volatile flavor compounds. Coffee brew samples were separated using standard sieves (with pore sizes of 850, 600, and $425{\mu}m$), making particle sizes of ground beans as follows: whole bean (control), $850{\mu}m$ or more (coarse), $850{\sim}600{\mu}m$ (medium), $600{\sim}425{\mu}m$ (fine), and $425{\mu}m$ or less (very fine). For each particle size category, pH, total acidity, brown color intensity, chromaticity, total phenolic content, caffeine content, chlorogenic acid content, and total amounts of volatile flavor compounds generated were compared and analyzed. As grinding grade decreased, pH and brown color intensity increased from 4.84 to 5.18 and from 0.257 to 0.284, respectively, whereas total acidity decreased from 0.31 to 0.17%. As grinding grade decreased, the $L^*$ and $a^*$ color values decreased; however, $L^*$ value did not exhibit a significant difference depending on the grinding grade. The $b^*$ value was 15.75 in the very fine size category, which showed the highest yellowness. There was an 11 or higher color difference between the control and ground coffee powder, indicating a remarkable color difference. The total phenolic, caffeine, and chlorogenic acid contents of the coffee brewed from ground beans with a very fine size were 4.54 mg gallic acid equivalent/mL, $733.0{\mu}g/mL$, and $383.7{\mu}g/mL$, respectively, which were high values. The total amounts of volatile compounds in the very fine size category were found to be greater than 100 mg/kg. In this study, we suggest the basis for coffee quality evaluation, which involves evaluating changes in the physicochemical properties and amounts of flavor compounds of coffee relative to the grinding grade of the beans (basic step of coffee extraction).

• Geomechanics and Engineering
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• v.30 no.3
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• pp.219-231
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• 2022

Geotechnical materials such as silt, fine sand, or coarse granular soils may be unstable under undrained shearing or during rainfall infiltration starting an unsaturated state. Some researches are available describing the instability of coarse granular soils in drained or undrained conditions. However, there is a need to investigate the instability mechanism of unsaturated silty soil considering the effect of degree of compaction and net confining stress under partially and fully drained conditions. The specimens in the current study are compacted at 65%, 75%, & 85% degree of compaction, confined at pressures of 60, 80 & 120 kPa, and tested in partially and fully drained conditions. The tests have been performed in two steps. In Step-I, the specimens were sheared in constant water content conditions (a type of partially drained test) to the maximum shear stress. In Step-II, shearing was carried in constant suction conditions (a type of fully undrained test) by keeping shear stress constant. At the start of Step-II, PWP was increased in steps to decrease matric suction (which was then kept constant) and start water infiltration. The test results showed that soil instability is affected much by variation in the degree of compaction and confining stresses. It is also observed that loose and medium dense soils are vulnerable to pre-failure instability i.e., instability occurs before reaching the failure state, whereas, instability in dense soils instigates together with the failure i.e., failure line (FL) and instability line (IL) are found to be unique.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.3
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• pp.46-59
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• 1980

This study was conducted to obtain the most effective distribution of grain size and the optimum lime content for lime-soil stabilization. To achieve the aim, the change of consistency, the characteristics of compaction and unconfined compressive strength were tested by adding of 0, 4, 6, 8, 10 and 12 percent lime by weight for all soils adjusted by given ratios of sand to clay. The results obtained were as follows; 1. There was a tendency that the plasticity index of lime-soil mixture was decreased by increasing the amount of lime, whereas the liquid limit was varied irregularly and the plastic limit was increased. 2. With the addition of more lime, the optimum moisture content of lime-soil mixture was increased, and the maximum dry density was decreased. 3. The optimum lime content of lime-soil mixture was varied from soil to soil, and the less amount of small grain size, the less value of optimum lime content. 4. The optimum distribution of grain size for lime-soil mixture was in the soil, having the ratio of about 60 percent of cohesive clay and about 40 percent of sand by weight. 5. In the soil having fine grain size, the effect of curing appeared for long periods of time, whereas the increasing rate of unconfined compressive strength was great on the soil of coarse grain size in the earlier stage of curing period.

• Preventive Nutrition and Food Science
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• v.18 no.4
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• pp.234-241
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• 2013

The aim of this study was to develop rice wine (Yakju) containing various amounts and particle sizes of ginseng powder and to analyze the physicochemical characteristics and content of ginsenosides in ginseng-Yakju. Soluble solid content, pH, ethanol concentration, acidity, amino acid content, and evaluation of preference showed no difference between four kinds of Yakju groups, regardless of ginseng supplementation and particle size of the ginseng powder. During fermentation of Yakju containing ginseng, the contents of ginsenosides Rb1, Rb2, Rb3, and Rc were decreased. Otherwise, the content of ginsenoside Rh1 was increased highly by brewing microorganisms in Yakju. Recovery ratios of ginsenosides in ginseng-Yakju were approximately 25.4% (coarse ginseng power) and 23.8% (fine ginseng powder), which were superior to the recovery ratio of ginsenosides in Yakju containing ginseng slices (5%).

• Geomechanics and Engineering
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• v.30 no.4
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• pp.393-399
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• 2022

The Segregation Potential (SP) is one of the most widely used predictors of frost heave in cold regions. Laboratory step-freezing tests determining a representative SP at the onset of the formation of the last ice lens (near the thermal steady state condition) can predict susceptibility to frost heave. Previous work has proposed empirical semi-log fitting for determination of the representative SP and applied it to several fine-grained soils, but considering only frost-susceptible soils. The presence of fines in coarse-grained soil affects frost susceptibility. Therefore, it is required to evaluate the applicability of the empirical semi-log fitting for both frost-susceptible and non-frost-susceptible soils with fines content. This paper reports laboratory frost heave tests for fines contents of 5%-70%. The frost susceptibility of soil mixtures composed of sand and silt was classified by the representative SP, and the suitability of the empirical semi-log fitting method was assessed. Combining semi-log fitting with simple laboratory frost heave testing using a temperature-controllable cell is shown to be suitable for both frost-susceptible and non-frost-susceptible soils. In addition, initially non-frost-susceptible soil became frost susceptible at a 10%-20% weight fraction of fines. This threshold fines content matched well with transitions in the engineering characteristics of both the unfrozen and frozen soil mixtures.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.253-259
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• 2021

Plastic wastes generated from household waste are separated by mixed discharge with foreign substances, and recycling is relatively low. In this study, the effect of the ratio and content of mixed plastic waste coarse aggregate(MPWCA)s and mixed plastic waste fine aggregate(MPWFA)s filled with blast furnace slag fine powder on the slump and compressive strength of concrete was evaluated experimentally. The MPWCAs were found to have a similar fineness modulus, but have a single particle size distribution with a smaller particle size compared to coarse aggregates. However, the MPWFAs were found to have a single particle size distribution with a larger fineness modulus and particle size compared to fine aggregates. Meanwhile, the effect of improving the density and filling pores by the blast furnace slag fine power was found to be greater in the MPWFA compared to the MPWCA. As the amount of the mixed plastic waste aggregate(MPWA)s increased, the slump and compressive strength of concrete decreased. In particular, the lower the slump and compressive strength of concrete was found to decrease the greater the amount of MPWFA than MPWCA when the amount of MPWA was the same. This is because of the entrapped air and voids formed under the angular- and ROD-shaped aggregates among the MPWFAs. On the other hand, the addition of the admixture and the increase in the unit amount of cement were found to be effective in improving the compressive strength of the concrete with MPWAs.

• Structural Engineering and Mechanics
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• v.92 no.2
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• pp.149-161
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• 2024

Previous research has identified inadequate flexibility in concrete pavements due to the use of high-strength concrete mixtures. This research investigates whether this problem can be addressed by partially replacing some fine and coarse aggregate components with waste rubber from shredded tires, the safe disposal of which otherwise is a major environmental concern. Using finite element software ABAQUS, this study analyses 3D pavement model behavior in terms of internal stress development and deflection at critical load points. This analysis is carried out for concrete slabs of differing waste rubber proportions and varying thicknesses. Results show that the maximum tensile stress is reduced, and maximum deflection is increased as the rubber content in pavement concrete slab is increased. The stresses and deflection of concrete pavement slab are reduced as the thickness of the slab is increased. The influence of increasing the base coarse modulus is significant in terms of reduction in tensile stress development. However, the reduction in deflection is found to be relatively marginal, especially in low-percentage rubberized pavement concrete slabs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.122-129
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• 2017

The aim of this study is a large amount use of recycled aggregates. The considering recycled aggregates replacement ratio is 50% that of natural aggregates. In order to increase the shear capacity of beams, that may be weaken by use of recycled aggregates, steel fibers are reinforced. The main variables are steel fiber volume fractions such as 0%, 0.5%, 0.75% and 1.0%. After the test, it could confirm that the strength and deformation capacity of beams with the steel fiber content values of 0.5% and 0.75% are comprehensively enhanced compared to non reinforcement. After evaluating the shear strength by using shear strength equations of previous researches, it concluded that the strength equation of Oh et al. (2008) is able to predict the shear strength of SFRC beams on the safety side.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.779-785
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• 1996

The qualities of bread and change of phytic acid during breadmaking with whole wheat flour were investigated. The ratios of ash contents in wheat flour and whole wheat flour were 0.41% and 1.57%, respectively. The ratios of fiber contents in wheat flour and whole wheat flour were 0.14% and 1.83%, respectively. In amino acid analysis, glutamic acid was determined to be 32~36g/100g protein, which was the highest. Lysine, glycine, arginine and aspartic acid were higher in whole wheat flour than those of wheat flour. Proline, glutamic acid, and phenylalanine were higher in wheat flour than those of whole wheat flour. The ratio of phytic acid content in wheat flour and whole wheat flour was 0.312% and 0.734%, respectively. The content of phytic acid during beadmaking was decreased approximately 65% after proofing, while this was almost constant in the process of oven baking. The content of phytic acid in bread with 3% yeast had less hydrolysis than that in bread with 5% yeast during breadmaking. The phytic acid content in the 0.1% yeast food was decreased more than the 0, 0.3, and 0.5% yeast food groups. As the amount of whole wheat flour increased, the volume of bread was decreased, and color became dark. The sensory evaluation was showed the quality of bread to be the highest when the amounts of coarse whole wheat flour and fine whole wheat flour was 20% and 30%, respectively. Though the amount of coarse whole wheat flour and fine whole wheat flour were increased up to 30% and 50%, respectively, external characteristics of bread was remained in normal.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.3
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• pp.160-166
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• 2007

The coarse deposit with a lower mud content adjacent to the shelf of the southern East Sea is probably a "relict" sediment deposited in response to a lower stand of sea level during the Pleistocene. The sediment that developed on the slope and in the deep sea was river-borne primarily and was secondarily reworked or redistributed by the Tsushima Warm Current from the East China Sea. The clay mineralogy of the area suggests various sources of fine-grained sediment from adjacent rivers, the Korea Strait, volcanic material from Ulleung Island, and the Japan coast. Massive sand, bioturbated mud, homogeneous mud, and laminated mud were the dominant facies found in the core sediments from the study area. The massive sand was mainly volcanic ash from an eruption on Ulleung Island (9300 yr BP) and consisted of colorless pumiceous glass and a black scoriaceous type. The sedimentation rates on the slope, based on the Ulleung-Oki ash layer, were about 10cm/ky higher than in the basin. Other than the coarse-grain sediment, the mean size of the fine sediment dominating the bioturbated and homogeneous muds in the basin and the laminated mud on the slope was 6-10 phi. This indicates a difference in the major sedimentary process: hemipelagic sedimentation in the Ulleung Basin and mass flow deposition, such as turbidite, on the slope of the southern East Sea.