• Geomechanics and Engineering
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• v.14 no.6
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• pp.581-588
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• 2018

In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

• Journal of Nutrition and Health
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• v.33 no.4
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• pp.365-373
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• 2000

The purpose of this study was to compare the nutritional effects of resistant starch, cellulose and pectin on growth rate, metabolic energy and apparent digestibility in rats. Forty eight male Sprague-Dawley rats were randomly assigned to six dietary treatments, Rats were fed, ad libitum one of six experimental diets: 5% of resistant starch (RS), 5% of cellulose (CE), 5% of pection(PT), 2.5% resistant starch and 2.5% cellulose(RS+CE), 2.5% resistant starch and 2.5% pectin(RS+PT), and 2.5% cellulose and 2.5% pectin (CE+PT) during 4 weeks. The results obtained were as follows: body weight gain were higher in groups RS and CE, compared with that in the group PT, where other groups such as RS+CE, RS+PT and CE+PT showed no significant differences to the RS group. Food intake and food efficiency into showed the same patterns. Metabolic energy were similar in the RS and CE, and was the lowest the metabolic energy in the group CE+PT was significantly low. Apparent digestibility of protein was significantly higher in the group RS, compared with the groups CE and PT. Apparent digestibility of mixed dietary fiber groups such as the RS+CE, RS+PT and CE+PT group were also higher compared with the group PT. Apparent digestibility of lipid were significantly higher in the groups RS, CE and PT. Apparent digestibility of lipid in the mixed pectin groups such as the RS+PT and CE+PT growth rate, metabolic energy and apparent digestibility of lipid in the mixed pectin groups such as the RS+PT and CE+PT recorded the lowest, while that of the group RS+CE was significantly high. From above results, following was concluded: The growth rate, metabolic energy and apparent digestibility of protein and lipid of group RS were significantly higher in comparision with the group PT, while availability of energy nutrients of group CE was similar to that of the group RS. Also resistant starch fed with pectin(RS+PT) seemed to have increased the growth rate and the apparent digestibility of protein compared with those of the group PT fed with pectin(PT) alone, however RS+PT scemed to have the apparent digestibility of lipid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.881-889
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• 1998

For the application of the commercially modified starch in frozen and retort foods, apparent viscosity and water loss were measured at each stages of heating, sterilization and freezing-thawing stages. Apparent viscosity showed the exponential increase with concentration and the slopes of apparent viscosity against concentration in the Firm-Tex(hydroxypropyl distarch phosphate), Hi-Flo(acetylated distarch adipate) and Colflo 67(acetylated distarch adipate) from waxy maize starch were higher than those of Amyloacetate M20(starch acetate) and X-amylo 250(distarch phosphare) from potato starch. In the presence of 1 or 2% NaCl, X-amylo 250 among modified starches showed the increase in water loss and the decrease in apparent viscosity, whereas Colflo 67, Hi-Flo and Firm-Tex were little affected by NaCl. In the presence of 1 or 2% sucrose, water loss and apparent viscosity of the modified starches were not affected. In the range of pH 4~8, water loss and apparent viscosity of the modified starches had no change but the differences were detected to some extent between each of heating, sterilization and freezing-thawing stages. In the apparent viscosity and water loss of the modified starches after 3 week storage from heating and sterilization, Hi-Flo, Amyloacetate M20 and X-amylo 250 were not changed at the storage period, and the overall acceptability of retort food containing the modified starches such as Firm-Tex and Amyloacetate M20 were favored more than others. In the apparent viscosity and water loss of the modified starches which have been frozen and thawed three times repeatedly, Colflo 67, Hi-Flo and Firm-Tex were not changed in freezingthawing, and the overall acceptability of frozen food containing Firm-Tex was most favored.

• KIEE International Transactions on Electrophysics and Applications
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• v.12C no.4
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• pp.229-235
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• 2002

The apparent volume resistivity of powders measured by both the tapping and the compressing methods was compared in this study. Factors such as applied voltage, pressure, corona charging, and so on affecting the apparent volume resistivity of polymer powders were also examined experimentally. Powders of polyacrylonitrile and Nylon 11 were mainly used. The values of the apparent resistivity of polymer powders taken by the tapping method turned out to be larger than those taken by the compressing method, which indicates that the apparent volume resistivity of polymer powders depends strongly on the measurement method. The apparent resistivity of polymer powders increased with an increase in applied voltage while it decreased with an increase in pressure, tapping time, and particle size. The influence of the moisture content of powder and corona charging on the resistivity of polymer powders is also discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.67-73
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• 2006

This investigation deals with the spin-up flows in a circular container of aspect ratio, 2.0. Shear front is generated in the transient spin-up process and propagating from the side wall to the central axis in a rotating container. Propagation of the shear front to the axis in a rotating container means the region acquires an angular momentum transfer from the solid walls. Propagating speed of the shear front depends on the apparent viscosity of polymer solution. Two kinds of polymer solutions are considered as a working fluid: one is CMC and the other is CTAB solution. CMC solution has larger apparent viscosity than that of water, and CTAB shows varying apparent viscosities depending on the applied shear rates. Transient and spatial variations of the apparent viscosities of the present polymer solutions (CTAB and CMC) cause different speeds of the propagating shear front. In practice, CMC solution that has larger values of apparent viscosity than that of water always shows rapid approach to the steady state in comparison of the behavior of the flows with water. However, for the CTAB solution, the speed of the propagating of the shear front changes with the local magnitude of its apparent viscosity. Consequently, the prediction of Wedemeyer's model quantitatively agrees with the present experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.2
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• pp.171-178
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• 2014

In this study, the apparent contact angle on the hydrophilic/hydrophobic surfaces with micropillars was studied. The previous researches showed that the Wenzel equation and the Cassie-Baxter equation were thermodynamically derived for the rough hydrophilic/hydrophobic surfaces and generally referenced on the field of wetting phenomena. For the verification of both equations, the apparent contact angle on the hydrophilic/hydrophobic surfaces with micro-pillars was measured. In the comparison between the measured and estimated apparent contact angles with the equations, the differences between the apparent contact angles were analyzed. Conclusively, the available range and limitation of theoretical equations were investigated and further researches about the apparent contact angle on the rough surfaces were proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2064-2070
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• 2009

According to recent researches, apparent power in a non-sinusoidal single phase system can be represented with geometric algebra. In this paper, the geometric algebra is applied to apparent power defined in a multi-line system having transmission lines with frequency-dependency under non-sinusoidal conditions.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1921_1922
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• 2009

According to recent researches, apparent power in non-sinusoidal single phase system can be represented with geometric algebra. In this paper, the geometric algebra is applied to apparent power defined in a multi-line system having transmission lines with frequency-dependent resistances under non-sinusoidal conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.387-394
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• 2001

An apparent earth pressure envelope for anchored walls proposed by FHWA was compared with Terzaghi & Peck's earth pressure envelope. The anchor design load, the maximum bending moment and the penetration depth were calculated by a simple beam analogy method for each type of envelope.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.33-40
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• 2009

In field surveys using the dipole-dipole electrical resistivity method, we often encounter negative apparent resistivity. The term 'negative apparent resistivity' refers to apparent resistivity values with the opposite sign to surrounding data in a pseudosection. Because these negative apparent resistivity values have been regarded as measurement errors, we have discarded the negative apparent resistivity data. Some people have even used negative apparent resistivity data in an inversion process, by taking absolute values of the data. Our field experiments lead us to believe that the main cause for negative apparent resistivity is neither measurement errors nor the influence of self potentials. Furthermore, we also believe that it is not caused by the effects of induced polarization. One possible cause for negative apparent resistivity is the subsurface geological structure. In this study, we provide some numerical examples showing that negative apparent resistivity can arise from geological structures. In numerical examples, we simulate field data using a 3D numerical modelling algorithm, and then extract 2D sections. Our numerical experiments demonstrate that the negative apparent resistivity can be caused by geological structures modelled by U-shaped and crescent-shaped conductive models. Negative apparent resistivity usually occurs when potentials increase with distance from the current electrodes. By plotting the voltage-electrode position curves, we could confirm that when the voltage curves intersect each other, negative apparent resistivity appears. These numerical examples suggest that when we observe negative apparent resistivity in field surveys, we should consider the possibility that the negative apparent resistivity has been caused by geological structure.