• Title/Summary/Keyword: 공극분포

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A Study on Pore Structure of High-Fluidity Concrete using Lime Stone Powder and Fly-ash (석회석 미분말 및 플라이 애시를 사용한 고유동 콘크리트의 공극구조에 관한 연구)

  • Choi, Yun-Wang;Hooton, R.D.;Eom, Joo-Han
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.3
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    • pp.118-125
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    • 2011
  • The size and distribution of concrete void was one among the factor determining durability of concrete. Recently, there was a lot of researches related to the High-Fludity Concrete(HFC) with field applications. However, the research about the void structure having an effect on durability of concrete is insufficient. Therefore, in this research, Conventional Concrete(CC) and HFC using lime stone powder and fly-ash of 30 MPa range was manufactured and observed the void structure of CC and HFC. Experimental results showed that average pore diameter in the case of the 30 MPa range HFC was to be lower than CC and SEM analyzed result, HFC was firmer inner structure than CC.

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Autogenous Shrinkage and Engineering Properties of the High Strength Concrete Using Soybean and Waste Edible Oil (식물성 유지 및 폐식용유를 사용한 고강도 콘크리트의 자기수축 및 공학적 특성)

  • Han, Min-Cheol;Lee, Dong-Gyu
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.3
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    • pp.110-117
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    • 2011
  • This study investigated possibilities for a new reducing shrinkage method of soybean oil(SO) and waste oil(WO) to compare with shrinkage reducing agent(RS) and expansion additive(EA). There was no big difference to flow, air contents, and compressive strength of plain to use SO and WO. For the reducing shrinkage performance, SO and WO was more effective than RS and EA, because their fatty acid reacted with calcium hydroxide of concrete to turn soap. For the pore distribution by porosimter, $0.01{\sim}0.1{\mu}m$ pores of SO and WO were 0 ml/g, and $10{\sim}100{\mu}m$ also remarkably lower than any others. In these results, it inferred that they filled up capillary pore and mitigated autogenous shrinkage by their saponification of their fatty acid and calcium hydroxide.

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A Study on the Comparative Evaluation of wearing Fitness of Women′s Ready-made Jackets Using 3D Scanner (3D Scanner를 이용한 여성용 기성복 재킷의 착의적합성에 관한 비교평가연구)

  • Kim, Haekyung;Eunyoung Suk;Park, Soonjee;Chuyeon Suh;Jiyoung Lim
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.10
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    • pp.1707-1718
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    • 2001
  • 본 연구 목적은 3차원 인체 스캐너를 이용하여 여자 기성복 재킷의 여유량을 비교, 분석하는 것으로, 2사이즈 7브랜드의 재킷의 공극량을 계측하여 분석하였다. 첫째, 재킷 단면둘레 분석 결과, B85(품), B8(허리)를 제외하고 브랜드간에 유의한 차이를 나타내지 않아, 전반적으로, 브랜드간 제품치수에는 차이가 없는 것으로 나타났다. 둘째, 인체와 재킷의 단면둘레 분석 결과, 재킷의 배둘레를 제외한 모든 항목에서 유의한 차이가 나타나 피험자, 재킷 모두 사이즈에 따라 유의적인 차이 가 있음을 알 수 있다. 셋째, 기본사이즈 B85에서는 허리를 제외하고는 패턴 F가 가장 여유량이 많은 것으로 나타났으나, B88의 경우, 부위별로 각기 다른 패턴에서 여유량이 가장 많은 것으로 나타나, 각 부분마다 브랜드별로 그레이딩 룰이 다름을 알 수 있다. 넷째, 착의 단면은 인체와 의복간의 여유량 분포를 명백히 보여주며, 어깨, 가슴, 엉덩이처럼 몸에 밀착되는 부위는 다른 부위에 비해 패턴간, 각도별 변이가 적은 것으로 나타났다. 품, 허리, 배에서는 옆보다는 앞, 뒤로, 가슴에서는 앞뒤 좌우의 30$^{\circ}$방향, 엉덩이의 경우, 옆, 뒤보다는 앞쪽에 여유량이 집중되어 있는 것으로 나타났다. 다섯째, 브랜드별 평균공극길이에 대한 분산분석 결과, 전반적으로 패턴 F가 가장 공극량이 많고, 패턴 D가 작은 것으로 나타났다. 여섯째, 사이즈별 평균공극길이에 대한 t-검정 결과, 품과 배 부분에서, B88이 B85보다 공극량이 적은 것으로 나타나, 기준부위인 가슴, 허리, 엉덩이 부분뿐만 아니라 품, 배둘레의 치수에 대응할 수 있도록 그레이딩 룰 값을 산정하여야 함을 알 수 있다.

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An Analytical Study of Chloride Ion Diffusion in Concrete via Cellular Automaton Method (셀룰러 오토마톤 법을 이용한 콘크리트의 염화물이온 확산현상의 해석적 연구)

  • Kim, Jeong-Jin;Seok, Won-Kyun
    • Journal of the Korea Institute of Building Construction
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    • v.24 no.5
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    • pp.541-552
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    • 2024
  • This study introduces a new analytical model known as the Cellular Automaton Method(CAM) designed to predict the degree of deterioration in concrete, taking into account its complex pore structure. The CAM model assesses the impacts of moisture migration, driven by capillary action and pressure differentials at the gas-liquid interface, which are influenced by the distribution of pores. It also evaluates how porosity and diffusion coefficients affect the penetration of chloride ions. The model's application revealed distinct moisture movement patterns in concrete structures, distinguishing between those with porosity levels below and above 40 percent. Additionally, it facilitated a comparison and analysis of chloride ion diffusion phenomena, based on diffusion coefficients in areas penetrated by moisture, against results obtained from the Finite Element Method(FEM). The comparison showed a maximum deviation of only 0.989 percent between the predicted outcomes of the FEM and CAM, demonstrating substantial agreement and validating CAM's efficacy in simulating the diffusion processes of chloride ions within concrete under actual salt damage conditions. Thus, CAM proves to be a reliable tool for modeling and anticipating deterioration in concrete structures exposed to saline environments.

The Effect of the Surfactant on the Migration and Distribution of Immiscible Fluids in Pore Network (계면활성제가 공극 구조 내 비혼성 유체의 거동과 분포에 미치는 영향)

  • Park, Gyuryeong;Kim, Seon-Ok;Wang, Sookyun
    • Economic and Environmental Geology
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    • v.54 no.1
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    • pp.105-115
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    • 2021
  • The geological CO2 sequestration in underground geological formation such as deep saline aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing the atmospheric CO2 emissions. The process in geological CO2 sequestration involves injection of supercritical CO2 (scCO2) into porous media saturated with pore water and initiates CO2 flooding with immiscible displacement. The CO2 migration and distribution, and, consequently, the displacement efficiency is governed by the interaction of fluids. Especially, the viscous force and capillary force are controlled by geological formation conditions and injection conditions. This study aimed to estimate the effects of surfactant on interfacial tension between the immiscible fluids, scCO2 and porewater, under high pressure and high temperature conditions by using a pair of proxy fluids under standard conditions through pendant drop method. It also aimed to observe migration and distribution patterns of the immiscible fluids and estimate the effects of surfactant concentrations on the displacement efficiency of scCO2. Micromodel experiments were conducted by applying n-hexane and deionized water as proxy fluids for scCO2 and porewater. In order to quantitatively analyze the immiscible displacement phenomena by n-hexane injection in pore network, the images of migration and distribution pattern of the two fluids are acquired through a imaging system. The experimental results revealed that the addition of surfactants sharply reduces the interfacial tension between hexane and deionized water at low concentrations and approaches a constant value as the concentration increases. Also it was found that, by directly affecting the flow path of the flooding fluid at the pore scale in the porous medium, the surfactant showed the identical effect on the displacement efficiency of n-hexane at equilibrium state. The experimental observation results could provide important fundamental information on immiscible displacement of fluids in porous media and suggest the potential to improve the displacement efficiency of scCO2 by using surfactants.

Pore Water Chemistry of Intertidal Mudflat Sediments: 1. Seasonal Variability of Nutrient Profiles (S, N, P) (조간대 퇴적물의 공극수 지구화학 : 1. 용존 영양염 (S, N, P)의 계절변화)

  • Lee, Chang-Bok;Kim, Dong-Seon
    • 한국해양학회지
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    • v.25 no.1
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    • pp.8-20
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    • 1990
  • A series of pore water data were obtained during the different time over one year period between October 1987 and October 1988, from a site on a muddy intertidal flat, located in the Kyeong-gi Bay, west coast of Korea, The results have revealed that the tidal flat is an environment of active nutrient the subface supplied by the overlying seawater is almost completely removed from the pore water at depth of about 10 cm below the sediment surface. The nutrients such as ammonium and phosphate are produced through this process and subsequently accumulated in the pore water forming steep gradients near the sediment surface. Below the main sulfate redirection zone, a secondary peak of dissolved sulfate was often observed. Greal seasonal variation of the pore water nutrient profiles was observed, which was particularly clear in their maximum concentration as well as in their concentration gradient. The rate constants of sulfate reduction and nutrient regeneration, estimated by using a diagenetic model (Berner, 1980), differ by an order of magnitude between the summer and winter seasons. The difference in sediment temperature may account for most of the calculated variation. The C:N:P ratio, calculated from the pore water nutrient gradients also exhibits a slight seasonal difference. The organic matter being decomposed by sulfate reduction appears to be depleted in depleted in nitrogen, compared to the average marine organic matter.

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The Effect of Temperature on the Process of Immiscible Displacement in Pore Network (공극 구조 내 비혼성 대체 과정에서 주입 온도가 유체 거동에 미치는 영향)

  • Park, Gyuryeong;Kim, Seon-ok;Lee, Minhee;Wang, Sookyun
    • Economic and Environmental Geology
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    • v.51 no.3
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    • pp.223-232
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    • 2018
  • The viscous force of fluids and the capillary force acting on the pore network of the porous media are important factors determining the immiscible displacement during geological $CO_2$ sequestration, these were directly affected by geological formation conditions and injection conditions. This study aimed to observe the migration and distribution of injected fluid and pore water, and quantitatively investigate displacement efficiency on various injection temperatures. This study aimed to perform micromodel experiments by applying n-hexane used as a proxy fluid for supercritical $CO_2$. In this study, immiscible displacement process from beginning of n-hexane injection to equilibrium of the distribution of the n-hexane and pore water was observed. The images from experiment were used to observe the displacement pattern and estimate the areal displacment efficiency of the n-hexane. For investigate the affects of the injection temperatures on the migration in macroscopic, migration of n-hexane in single pore was analyzed. The measurement revealed that the displacement efficiency at equilibrium state decreases as the temperature increases. The result from experiments indicate that the temperatures can affect the displacement pattern by changing the viscous forces and the capillary forces. The experimental results could provide important fundamental information on reservoir conditions and fluid injection conditions during geological $CO_2$ sequestration.

Effect of Cyclic Injection on Migration and Trapping of Immiscible Fluids in Porous Media (공극 구조 내 교차 주입이 비혼성 유체의 포획 및 거동에 미치는 영향)

  • Ahn, Hyejin;Kim, Seon-ok;Lee, Minhee;Wang, Sookyun
    • Economic and Environmental Geology
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    • v.52 no.1
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    • pp.37-48
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    • 2019
  • In geological $CO_2$ sequestration, the behavior of $CO_2$ within a reservoir can be characterized as two-phase flow in a porous media. For two phase flow, these processes include drainage, when a wetting fluid is displaced by a non-wetting fluid and imbibition, when a non-wetting fluid is displaced by a wetting fluid. In $CO_2$ sequestration, an understanding of drainage and imbibition processes and the resulting NW phase residual trapping are of critical importance to evaluate the impacts and efficiencies of these displacement process. This study aimed to observe migration and residual trapping of immiscible fluids in porous media via cyclic injection of drainage-imbibition. For this purpose, cyclic injection experiments by applying n-hexane and deionized water used as proxy fluid of $scCO_2$ and pore water were conducted in the two dimensional micromodel. The images from experiment were used to estimate the saturation and observed distribution of n-hexane and deionized water over the course drainage-imbibition cycles. Experimental results showed that n-hexane and deionized water are trapped by wettability, capillarity, dead end zone, entrapment and bypassing during $1^{st}$ drainage-imbibition cycle. Also, as cyclic injection proceeds, the flow path is simplified around the main flow path in the micromodel, and the saturation of injection fluid converges to remain constant. Experimental observation results can be used to predict the migration and distribution of $CO_2$ and pore water by reservoir environmental conditions and drainage-imbibition cycles.

Mechanical Characteristics of Basalt in Jeju Island with Relation to Porosity (공극률에 따른 제주도 현무암의 역학적 특성)

  • Moon, Kyoungtae;Park, Sangyeol;Kim, Youngchan;Yang, Soonbo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.4
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    • pp.1215-1225
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    • 2014
  • Volcanic rocks formed from magma near the earth surface commonly show vesicular structures due to exsolution of gaseous phases in magma. The distinction and the amount of vesicles are greatly various, but there are few researches on the effect of volume percentage of vesicles on the mechanical properties. In this study, mechanical characteristics of volcanic rocks in relation to the porosity are investigated through experimental tests with Jeju basalt. Two methods (the buoyancy method and the caliper method) are adopted for measuring porosity. And unconfined compressive strength, elastic modulus, tensile strength, and elastic wave velocity are plotted against porosity in order to propose the empirical relations after the regression analysis. Also, unconfined compressive strength and the elastic modulus in relation to the elastic wave velocity are proposed with the analysis. In the case of vesicular rocks with more than 5% porosity, it is found that the buoyancy method provides more accurate estimation of porosity than the caliper method. The unconfined compressive strength, the elastic modulus, and the elastic wave velocity decrease curvilinearly with increasing in porosity. Also, the unconfined compressive strength and the elastic modulus increase linearly with increasing in elastic wave velocity.

Analysis of Electromagnetic Field of Squirrel-cage Induction Motor Using 3D FEM Program (3차원 유한요소 프로그램을 이용한 농형 유도전동기의 전자계해석)

  • Lee, Suk-Won;Shin, Pan-Seok
    • Proceedings of the KIEE Conference
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    • 1999.07a
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    • pp.327-329
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    • 1999
  • 본 논문은 3차원 유한요소 프로그램을 이용한 농형 유도전동기의 정자장을 해석한 것이다. 2차원영역에서 해석하기 어려운 누설 인덕턴스를 3차원으로 해석하여 설계 파라미터 선정에 도움을 주고자 하였다. 유도전동기의 공극 자속밀도 분포와 누설 자속밀도 분포를 고찰하고 1[turn]의 coil에 의해 발생하는 자속의 량과 전동기 내부로 통과하는 자속의 량을 비교하여 누설 인덕턴스를 계산할 수 있었다.

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