• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.225-226
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• 2013

Existing polyurethane membrane waterproofing has been raised defects such as heaving. Therefore, We will be utilizing as the basic experimental data by the water vapor permeability test to the air cell structure of ultra rapid harding membrane waterproofing using the static mixing system in this study.

• Computers and Concrete
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• v.7 no.5
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• pp.469-482
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• 2010

This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller's curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.189-195
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• 2006

In this paper, the inductance characteristics of interior permanent magnet synchronous motor (IPMSM) considering cross-coupling effect is analyzed. It is known that the IPMSM has it's operating point at the saturated region. So the cross-coupling effect exists, therefore cross-coupling inductance exists. With the application of Fixed Permeability Method (FPM), we can obtain more exact inductance characteristics of IPMSM. In this paper, a novel method based on the FPM is proposed, which can consider the cross-coupling effect. And the cross-coupling inductance which is the analysis result is shown. Finally, the validity of proposed method is verified by the comparison with the experimental result.

• Proceedings of the KIEE Conference
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• summer
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• pp.941-943
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• 2004

고정 투자율법이란 (Fixed Permeability Method : FPM) 시스템이 자기적으로 포화 상태에 있을 때 각 요소별 동작지점의 투자율을 고정하여 선형적으로 시스템을 재해석하는 방법으로, 두 가지 이상의 자계원에 의해 포화가 발생할 경우, 각각의 영향을 구분지어 포화시 철심내의 자계 비선형 문제를 해석할 수 있다. 본 논문에서는 제안된 고정 투자율법을 적용하여 자기 포화가 발생하는 영역까지를 운전 영역에 포함하는 매입형 영구 자석 전동기의 특성 값들을 추출하는 방법을 제시하였으며, 실험값과의 비교를 통해 그 타당성을 검증하였다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.997-999
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• 2003

고정투자율법이란 (Fixed Permeability Method) 시스템이 자기적으로 포화 상태에 있을 때 각 요소별 동작지점의 투자율을 고정하여 선형적으로 시스템을 재해석하는 방법으로, 본 논문에서는 제안된 고정투자율법을 적용하여 두 가지 이상의 자계원에 의해 포화가 발생할 경우 각각의 영향을 구분 지어 포화시 철심내의 자계 비선형 문제를 해석하였다. 아울러 철심형영구 자석 선형 동기 전동기(PMLSM, Steel-Cored Permanent Magnet Linear Synchronous Motor)에서 대전류 인가시 발생하는 철심 포화 특성을 규명하였고 해석의 타당성을 실험값과의 비교를 통해 검증하였다.

• Membrane Journal
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• v.15 no.1
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• pp.62-69
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• 2005

SEBS-clay hybrid membranes were prepared by melt intercalation method with internal mixer. In the hybrid, the amount of clay content was fixed to 5 phr. MMT was intercalated or exfoliated by the ionomer and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in SAXD was moved and diminished. Gas permeability, mechanical properties and thermal properties of the SEBS-clay hybrid membranes were investigated. Gas permeability through the SEBS-clay hybrid membranes decreased due to increased tortuosity made by intercalation of clay in SEBS.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.85-92
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• 2003

Generally, ordinary portland cement(OPC) is widely used for grouting to reduce permeability of ground under the foundations of structures. But, it is hard to be injected into the microscopic voids, fissures and crevices in soil or rock formation for the OPC material. Therefore new method what is called MSG(Micro Silica Grouting) has been developed recently to improve the weak point of the OPC material. In this case study, in order to verify performance of the MSG's water cut-off, trial injections were performed in rear of CIP(Cast in Place Pile) on the site A(weathered soil) and B(alluvial soil) that are constructed for the subway No. 9 nowadays. To take the proper grouting method of the MSG in the trial injecting, the injections are carried out for grouting types(constant pressure or fixed Quantity) and grouting methods(1.5shot or 2.0shot) and to confirm the effects of water cut-off and the injection range of the MSG, the tests of permeability and indicator(phenolphthalein) response were performed before and after the injection. Through the tests results, we could affirm the effects of water cut-off of the MSG and the injection range for the weathered and alluvial soil layers near the Han River. Finally we could make sure the application of the MSG method in actual construction under the layers.

• Membrane Journal
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• v.15 no.2
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• pp.165-174
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• 2005

Sulfonated poly(styrene-ethylene-butadiene-styrene) (SSEBS)-clay hybrid membranes were prepared by solution method. In the preparation of hybrid membrane, the amount of clay content was fixed to 5 phr and montmorillonite (MMT) was fully exfoliated by the SEBS and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in WAXD was fully diminished. Gas permeability, mechanical properties and thermal properties of the SSEBS-clay hybrid membranes were investigated. Gas permeability through the SSEBS-clay hybrid membranes decreased due to increased tortuosity made by exfoliation of clay in SEBS.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.576-587
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• 2010

Background: Effective decellularization and fixation process is critical, in order to use xenogenic valves clinically. In the present study, we decellularized bovine pericardium using sodium dodecyl sulfate (SDS) and N-lauroyl sarcosinate, treated with $\alpha$-galactosidase, and then fixed in various manners, to find out the most effective tissue preservation & fixation procedure. Material and Method: Bovine pericardium was decellularized with SDS and N-lauroyl sarcosinate, and treated with $\alpha$-galactosidase. Both groups were fixed differently, by varying glutaraldehyde (GA) or EDC (1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide)/N-hydroxysuccinamide (NHS) treatment conditions. Thereafter, physical examination, tensile strength test, thermal stability test, cytotoxicity test, pronase test, pronase-ninhydrin test, purpald test, permeability test, compliance test, H&E staining, DNA quantification, and $\alpha$-galactose staining were carried out to each groups. Result: GA fixed groups showed better physical properties and thermal stability than EDC/NHS fixed groups, EDC/NHS-GA dual fixed groups showed better physical properties and thermal stability than EDC/NHS fixed groups, and showed better thermal stability than GA fixed groups. In pronase test and pronase-ninhydrin test, GA fixed groups and EDC/NHS-GA dual fixed groups showed stronger crosslinks than EDC/NHS groups. Permeability and compliance tended to increase in EDC/NHS-GA dual fixed groups, compared to GA fixed groups. But, EDC/NHS-GA dual fixed groups had stronger tensile strength and lower cytotoxicity than GA fixed groups. Conclusion: We have verified that EDC/NHS-GA dual fixation can make effective crosslinks and lower the toxicity of GA fixation. Henceforth, we will verify if EDC/NHS-GA dual fixation can lower calcifications & tissue failure in vivo experiment.

• Journal of the Korean GEO-environmental Society
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• v.16 no.8
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• pp.5-12
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• 2015

In this study, buoyancy-resistance permanent anchor was considered to prevent uplift pressure of a building structure. However, this test was failed to put anchor body in the boring hole because of the rapid outflow of ground water and coefficient of permeability. In addition, the hole where the anchor body was forcefully inserted constantly flew the sea water and cement. And it was found that anchor was not settled in the ground. In order to solve this problem, jet grouting method was applied to block the ground water and the single grouted column method was chosen to install the buoyancy-resistance permanent anchor. In this paper, the single grouted column method was applied with the general jet grouting methods and grout material was fixed by 3-field tests. These tests confirmed the effect of permeability and ground improvement with field permeability test by core sampling, Standard Penetration Test (SPT) and unconfined compression test. Confirming the stability of the buoyancy-resistance permanent anchor with installation and tension test, application of the single grouted column method in the volcanic clastic zones was verified.