• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.443-448
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• 1999

Tests have been carried out on four concrete containing different levels of silica fume to measure their permeability coefficient using water and oxygen, chloride ion. The total cementitious content was 351kg/㎥, and the water/cementitious materials ratio was 0.55. The results show that a dramatic reduction in permeability of concrete containing silica fume occurs due to formation of a discontinuous macro-pore system which inhibits flow. Porosity estimates from mercury-intrusion porosimetry are used to develop an explanations for the water and air permeability reduction. And, results of the rapid permeability test showed that the resistance of concrete to the penetration of chloride ions increases significantly as a contents of silica-fume is increased. The current intensity passing through the concrete containing silica fume is presented from 664C to 2166C.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1994년도 추계 학술발표회
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• pp.42-43
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• 1994

• 한국건축시공학회지
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• 제4권1호
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• pp.119-126
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• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• 한국지반신소재학회논문집
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• 제7권4호
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• pp.1-8
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• 2008

토양증기추출공법(SVE)은 불포화 지반상태에서 휘발성 유기화합물(VOCs)과 유류오염 물질을 제거하는데 효과적이고 경제적인 공법중의 하나이다. 그러나 토양증기추출공법은 투기계수가 1 Darcy보다 작은 실트질 흙과 같이 낮은 투기계수를 가진 지반에서는 비효율적이다. 본 연구의 목적은 연직배수재를 토양증기추출기술중 관정으로서의 적용성과 공기 흐름 패턴에 대한 해석적 방법이다. 즉, 연직배수재를 이용한 실내 모형실험의 공기 추출 시험 결과를 바탕으로 하여 단일 배수재로서의 수치해석 모델을 검증하였다. 또한, 추출 시험결과로 투기계수를 결정하여 단순 분석적 접근의 유효성도 평가하였다.

• Journal of the Korean Wood Science and Technology
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• 제46권6호
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• pp.637-644
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• 2018

The air permeability of yellow poplar log cross section before and after organosolv pretreatment was investigated, and the moisture absorption of control and organosolv pretreated rectangular parallelepiped specimens was investigated in this study. It was revealed that the diameters of through pores were enlarged and the number of bigger pore was increased by the organosolv pretreatment. The air permeabilities of the cross sections of yellow poplar log were changed from 1.61 darcy to 23.30 darcy, but their weights were reduced by 5 percent. The equilibrium moisture content of control wood specimen at the exposed relative humidity were 5.9 % at 32 %, 9.7 % at 58 %, 14.8 % at 80.5 %, 19.7 % at 90 %, 25.7 % at 95 % and 29.9 % at 100%. The equilibrium moisture content of the specimens pretreated with the parameter of sulfuric acid catalyst of 0.5 % (w/w) were 19.5 % at 32 %, 29.3 % at 58 %, 39.6 % at 80.5 %, 59 % at 90 %, 111.3 % at 95 % and 111.3 % at 100 %, while those pretreated with the parameter of sulfuric acid catalyst of 1.0 % (w/w) were 17.4 % at 32 %, 23.9 % at 58 %, 27.7 % at 80.5 %, 40.6 % at 90 %, 68.8 % at 95 % and 110.0 % at 100 %. The moisture absorption of organosolv pretreated rectangular parallelepiped specimens was higher than that of control specimen.

• 원예과학기술지
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• 제16권2호
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• pp.229-232
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• 1998

수입 육묘용 포트원지를 분석한 결과, 사용환경 특성상 일반종이보다 높은 습윤강도를 가지고 있었다. 습윤상태에서의 강도가 건조상태의 약 35% 이상의 인장강도와 약 60% 이상의 파열강도를 나타내었다. 육묘판의 강도를 유지하기 위해서 합성섬유를 약 30% 혼용하고 있었다. 또한 수분, 공기 등의 효율적 이동을 위하여 Gurley sec.로 측정한 투기도가 약 10초로 높은 수준이었다. 수입한 육묘용 포트원지와 유사하도록 실험실적으로 제조한 포트원지의 사이즈도는 AKD를 무게비로 건조 펄프의 0.5%를 첨가하여 충분히 얻을 수 있었다. 0.5% 이상 투입할 경우 사이즈 효과는 향상되나 강도 저하의 원인이 되었다. 강도적 측면에서는 Finex-B를 건조 펄프 무게에 대해 2%를 첨가하는 것이 가장 좋은 결과를 보였다. 실험실적으로 제조한 포트원지는 강도적 측면에서는 수입 포트원지보다 우수하나, 투기도가 다소 낮으므로 이를 개선하기 위한 노력이 필요하다.

• 콘크리트학회논문집
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• 제13권5호
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• pp.484-490
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• 2001

본 연구는 라텍스 혼입률을 5, 10, 15, 20%로 변화함에 따른 염소이온 투수성과 동결융해저항성 관점에서 라텍스 개질 콘크리트의 내구특성을 고찰하고자 한다 콘크리트에 라텍스가 혼입되고 양생되었을 때 콘크리트는 라텍스 입자의 필름막에 의해 서로 연결된 시멘트수화물과 골재가 구성된다. 이때 라텍스의 양이 증가함에 따라 콘크리트의 휨강도는 증진되나, 압축강도는 다소 저하된다. 이와 같은 휨강도의 증가는 시멘트수화물과 골재사이의 라텍스 필름막에 기인한 것이며 압축강도의 감소는 라텍스의 성분 중 부타디엔의 유연성 때문에 발생되는 것으로 판단된다. 라텍스 개질 콘크리트와 보통콘크리트의 상대 투수성을 측정하기 위하여 염소이온투과시험법을 사용하였다. 실험 결과 라텍스 개질 콘크리트의 투수성은 보통콘크리트의 투수성보다 매우 낮음을 알 수 있었다. 이것은 라텍스 미립자가 미세공극을 충전하고 라텍스 입자의 필름막에 의해 골재와 시멘트수화물이 연결되었기 때문이다. 그리고 라텍스 개질 콘크리트의 동결융해저항성은 보통콘크리트에 비해 매우 높으며, 보통콘크리트에서는 동결융해저항성을 증가시키기 위해 공기연행제를 필요로 하지만, 라텍스 개질 콘크리트에서는 적절한 양생이 이루어지면 추가적인 공기연행제는 요구되지 않는다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1170-1176
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• 2006

This study aims to investigate numerically the static and dynamic stiffness characteristics of porous air bearing and to estimate appropriate permeability values of porous medium. In particular, a new roughness model is proposed and implemented into the commercial CFD code (FLUENT Ver.6.2). The predicted results are extensively compared with experimental data for static cases. The roughness model is also validated through comparison with the results from open literature. For the dynamic cases, the deforming and re-meshing technique is used for describing fluid-solid interactions. It is found that the predictions for static stiffness are in good agreement with experimental data and the dynamic stiffness appears to be relatively smaller than the static stiffness. In addition, moving and dynamic analysis of air bearing seems to be possible to provide qualitative predictions even if there are somewhat discrepancies quantitatively, compared to experimental data.

• Nuclear Engineering and Technology
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• 제37권6호
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• pp.537-556
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• 2005

A primary-pipe rupture accident is one of the design-basis accidents of a High-Temperature Gas-cooled Reactor (HTGR). When the primary-pipe rupture accident occurs, air is expected to enter the reactor core from the breach and oxidize in-core graphite structures. This paper describes an experiment and analysis of the air ingress phenomena and the method fur the prevention of air ingress into the reactor during the primary-pipe rupture accident. The numerical results are in good agreement with the experimental ones regarding the density of the gas mixture, the concentration of each gas species produced by the graphite oxidation reaction and the onset time of the natural circulation of air. A hydrogen production system connected to the High-Temperature Engineering Test Reactor (HTTR) Is being designed to be able to produce hydrogen by themo-chemical iodine-Sulfur process, using a nuclear heat of 10 MW supplied by the HTTR. The HTTR hydrogen production system is first connected to a nuclear reactor in the world; hence a permeation test of hydrogen isotopes through heat exchanger is carried out to obtain detailed data for safety review and development of analytical codes. This paper also describes an overview of the hydrogen permeation test and permeability of hydrogen and deuterium of Hastelloy XR.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.382-388
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• 2005

Soil vapor extraction(SVE) is an effective and cost efficient method of removing volatile organic compounds(VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. Prefabricated vertical drains(PVDs) have been used for dewatering fine-grained soils for more than 25 years. Incorporating PVDs in and SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. The objective of the work described herein was to effectively incorporate PVDs into a SVE remediation system and to demonstrate a PVDs enhanced SVE system at full scale. The finding from this research will facilitate the design of field PVD-SVE systems in terms by providing insight into the optimal spacing between PVDs, the radius of influence of the wells and the flow rates to be used to capture and extract gas phase contaminants.