• Title/Summary/Keyword: Void Distribution

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Effect of Shell Structure of Artificial Lightweight Aggregates on the Emission Rate of Absorbed Water (인공경량골재의 표피층 구조가 흡수된 물의 방출속도에 미치는 영향)

  • Kang, Seung-Gu
    • Journal of the Korean Ceramic Society
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    • v.45 no.11
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    • pp.750-754
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    • 2008
  • The artificial aggregates with dense surface layer (shell) was fabricated and the dependence of water emission rate upon the shell structures was studied. The EAF dust containing many flux components and waste white clay with ignition loss of above 48% were used as for liquid phase and gas forming agents during a sintering process respectively. In addition, the shell structure was modified with various processes and the modification effect on water emission rate was analyzed. The pores under $10{\mu}m$ were found in the sintered artificial light aggregates and disappeared by incorporating to a bigger pore during re-sintering. The water emission rate in an initial step depended on a void content of aggregates filled in a bottle rather than a shell structure. But, after 7 days where the water emission of the aggregate with a shell is above 40%, the shell of aggregates suppressed the water emission. The core of aggregates was exposed and most shell was lost when crushed to smaller size so, the ability for suppressing water emission of the crushed aggregates decreased. The activation energy for the water emission was $3.46{\pm}0.25{\times}10^{-1}$J/mol for the most specimens showing that the activation energy is irrelevant to the pore size distribution and shell structure.

Soil Characteristics of soft clay in Nakdong-River Basin by considering Sample Disturbance (시료교란 정도를 고려한 낙동강 하구 유역 점토의 토질역학적 특성)

  • 이경은;정두회
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.111-118
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    • 2002
  • Recent study of soft clay of Nakdong-River basin has been taken correlation between soil properties by regression analysis without distribution whether the sample is disturbed or not, or treated as a whole area without proposing local correlation equation to Jang-U or Dae-Joe which has a specific locality. Accordingly, Those tendency cause the reliability of correlation between compression index and void ratio low and then design underestimate and uncertain eventually. In this study, Distributing the soft clay of Nakdong-River basin with failure strain of 6%, the suggestion by Skempton(1957), TakeNaka(1966)-the more sample is undisturbed, the more the ratio of E$\_$50/ and q$\_$u/, ${\alpha}$ = E$\_$50//(q$\_$u//2) = 1/$\varepsilon$$\_$50/ is high-is satisfied with the value of which ${\alpha}$ is 50 and It could be taken enough data in the condition of domestic. Besides other indices also make the distribution suitable. In conclusion, This study is supposed to propose the locally subdivided regression equation between compression index and void ratio considering the sample disturbance.

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Probability Distribution of Geotechnical Properties of Songdo area in Incheon (인천 송도지역 지반정수의 확률분포 추정)

  • Kim, Dong-Hee;Kim, Min-Tae;Ko, Seong-Kwon;Park, Jung-Gyu;Lee, Woo-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1399-1406
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    • 2009
  • Probability distribution of geotechnical properties is very useful information and it is used for evaluating the geotechnical properties itself and calculating probability of failure. In this study, probability distribution of compression index, recompression index, and void ratio are evaluated, and analysis results show that all property distributions satisfy normal and log-normal distribution.

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EFFECT OF COATING COMPOSITION IN DOUBLE COATING ON THE PENETRATION OF FINE PARTICLES INTO SUBSTRATE

  • Kim, Byeong-Soo;Douglas W. Bousfield
    • Journal of the Korean Graphic Arts Communication Society
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    • v.18 no.1
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    • pp.1-11
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    • 2000
  • The influence of the first coating layer on the properties of the second coating layer is reported. For various model coating composition, ratios of first and second coating weights are used to generate coating layers. The void volume, pore size distribution and light scatter coefficient of the coatings are measured. In some cases, the fine material from the second layer seems to penetrate the first layer to reduce the void fraction of the total system. Rapid setting coating, for example thin layers on porous first layer tends to generate porous coating layers.

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Centrifuge Model Experiments on One-dimensional Consolidation of Soft Clay with Surcharges (상재하중에 의한 연약점토의 일차원 압밀에 관한 원심모형실험)

  • Yoo, Nam-Jae;Lee, Myung-Woog;Lee, Jong-Ho
    • Journal of Industrial Technology
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    • v.17
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    • pp.103-110
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    • 1997
  • This thesis is to investigate the one-dimensional consolidation behavior of soft marine clay with uniform surcharges by perfoming numerical and experimental works. Parametric experimental works of centrifuge model test were carried out changing test conditions of gravitational level in centrifuge, magnitude of surcharges and construction sequence of applying surcharges. Results of centrifuge model experiments were analyzed by using the numerical technique of explicit finite difference method based on the finite strain consolidation theory, being known to be appropriate to analyze the consolidational behavior of soft clay with a very high initial void ratio using the Lagrangian and the material coordinate systems. Test results were in relatively good agreements with analyzed results in terms of excess pore pressure dissipation and consolidation settlement with time and final void ratio distribution.

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Soil-Water Characteristic Curves of Residual Soils and Deformable Soils (풍화잔적토와 체적이 변하는 흙의 흙-수분 특성곡선)

  • 이인모;이형주;김기섭
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03b
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    • pp.265-272
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    • 2000
  • This study introduces the current theory of the SWCC and tries to verify the theory by performing laboratory tests for the local soils of Korea. First, the SWCCs of Poi-dong soil and Shinnae-dong soil, the most typical weathered residual soils in Korea, were experimentally obtained and the results were compared among others. Second, a SWCC model for deformable soils was proposed. For deformable soils, which show huge volume change during desaturation, the volume change behavior should be considered, and the SWCC should be expressed as a function of void ratio as well as suction.

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Air Contents & Size Distribution of Air Voids in Concrete Using Image Analysis (이미지 분석에 의한 콘크리트의 공극 분포 및 공기량 분석)

  • Kwon, Hyouk-Chan;Jeong, Won-Kyong;Yun, Kyong-Ku
    • Journal of Industrial Technology
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    • v.24 no.A
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    • pp.157-164
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    • 2004
  • Air voids in hardened concrete have an important influence on concrete durability such as resistance of freezing and thawing, permeability and surface scaling resistance. Linear traverse method and point count method in ASTM standard method have been widely used to estimate the air void system in hardened concrete. However, these methods are not used at present time, because they are is exhausted much time and effort. In previous study, air voids system of concrete was estimated by spacing factor. The purpose of this study organizes image analysis method by analyzing air contents, air voids distributions by diameters, air voids system as well as spacing factors after hardened concrete. The experimental variables institute of depth of specimen(top, middle, bottom), air contents(AE contents 0, 0.01, 0.03%).

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Modeling Heterogeneous Wall Nucleation in Flashing Flow of Initially Subcooled Water

  • Park, Jong-Woon
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05b
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    • pp.241-246
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    • 1996
  • An analytical model to calculate rate of vapor generation due to heterogeneous wall nucleation in flashing flow is developed. In the present model, an important parameter of the vapor generation term, i.e. nucleation site density is calculated by integrating its probability distribution function with respect to active cavity radius. The limits of integration are minimum and maximum active cavity radii, and these are formulated using an active cavity model for nucleate boiling. This formulation, therefore. can statistically account for the effect of surface specific thermo-physical and geometric conditions on the vapor generation rate and flashing inception. For verifying the adequacy of the present model, steady state two-fluid and the bubble transport equations are solved with applicable constitutive equations. The applicable region of the bubble transport equation is also extended to churn-turbulent flow regime to predict interfacial area concentration at high void fraction. Predicted results in terms of axial pressure and void fraction profiles along the channels are compared with experimental data of Super Moby Dick and BNL Reasonable agreements have been achieved and this shows the applicability of the present model to flashing flow analysis.

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Frequency Spectra of AC Signal Generated from the Operation of Cast-Resin Power Transformer (운전중인 몰드형 전력변압기의 음향방출신호에 대한 주파수 스펙트럼 특성)

  • 구경철;이상우;이동인;이광식;김인식;김이국;신용철
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2000.11a
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    • pp.246-250
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    • 2000
  • In this paper, Frequency spectra of AE(acoustic emission) signals generated from the magnetizing and the load currents in the actual operating cast-resin power transformer of 500[kVA] under distribution system of22.9[kV] were also analysed to distinguish the AE signals due to void discharges from the magnetic circuit noises in the core of cast-resin power transformer. As the experimental results, we could distinguish the AE signals whether those signals were caused due to the void discharges or due to the magnetic circuit noises by analyzing the frequency spectrum of AE signals. Frequency spectra of AE signals generated from the cast-resin power transformer in operation due to both the magnetizing and the load currents appeared in the range of 40-120[khz].

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Partial Discharge Characteristics of Epoxy Composite due to Internal Void (Epoxy 복합체의 내부 보이드에 따른 부분방전특성)

  • Kim T. Y.;Shin J. Y.;Lee J. H.;Lee D. J.;Hong J. H.
    • 한국컴퓨터산업교육학회:학술대회논문집
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    • 2003.11a
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    • pp.55-58
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    • 2003
  • Stability of inside power equipments are required for electron equipment in order to operate those safely. Also, the power circuits for these have been developing, but research of dielectric strength of power supply is insufficient. In this paper, for test insulation condition variation by void it is tested insulation characteristics variation, using $\phi-q-n$ distribution variation in partial discharge test.

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