• Geomechanics and Engineering
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• 제14권6호
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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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• 제33권4호
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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.

• 한국식품영양과학회지
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• 제27권5호
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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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• 제12C권4호
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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.

• 대한기계학회논문집B
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• 제30권1호
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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.

• 한국정밀공학회지
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• 제31권2호
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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.

• 전기학회논문지
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• 제58권10호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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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.

• 지구물리와물리탐사
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• 제12권1호
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• pp.33-40
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• 2009

쌍극자-쌍극자 전기비저항 탐사를 수행하여 자료를 얻다 보면 종종 음의 겉보기 비저항값을 얻게 된다. 음의 겉보기 비저항이란 겉보기비저항 가단면도 상에서 주변자료와 반대되는 부호를 갖고 나타나는 비저항을 의미한다. 이러한 음의 겉보기 비저항은 보통 측정오차로 간주되어 현장 자료 해석시 무시되어 왔다. 일부 측정기기에서는 겉보기 비저항의 절대간이 기록되므로 이러한 음의 비저항값들이 주변값과 같은 부호를 갖는 것으로 환산되어 해석되기도 한다. 현장에서의 여러 실험 결과 옴의 겉보기 비저항갈은 측정오차나 자연전위의 영향에 의해 나타나는 현상이 아니었으며, 유도분극에 의한 영향도 아니었다. 한가지 가능성으로 지하 지질구조에 의한 영향으로 생각할 수 있다. 이 연구에서는 수치모델링을 통하여 평탄한 지형에서 음의 비저항이 지하 지질구조에 의하여 나타날 수 있다는 것을 보여준다. 현장자료를 시뮬레이션하기 위하여 3차원 전산모델링 알고리즘을 이용하였으며, 3차원 결과로부터 2차원 가단면도를 얻었다. 음의 비저항을 발생시키는 모델로는 U자형과 초승달모양의 전도체 모델을 가정하였다. 수치모델링 결과 이러한 지질구조로부터 음의 비저항이 나타날 수 있다는 것을 확인할 수 있었다. 일반적으로 전류전극으로부터의 거리가 멀어질수록 전위값이 증가하게 되면 전위차 곡선들이 서로 교차하면서 음의 비저항값이 나타나는데, 본 연구에서 제시된 결과들에 대해 전극위치에 대한 전위차 그래프를 그려봄으로써 이를 확인할 수 있었다. 본 연구에서 제시한 수치예제들은 현장조사에서 획득한 음의 겉보기 비저항값들이 지하 지질구조에 의해 발생할 수 있는 가능성을 제시하며, 향후 현장조사 자료 해석시 이를 고려하여 해석할 것을 제안한다.