• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.239-246
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• 2014

High volume slag concrete is attracting new attention and are thought to have promising potential for industrial applications, partly due to the climate debate, but especially due to their very low heat of hydration and their good durability in chemically aggressive environments. However, High volume slag concretes tend to have slower strength development especially. In this study, the effect of anhydrite ($CaSO_4$) on the mechanical and durability performance of high volume slag concrete were investigated. The main variables were anhydrite contents (0, 4, 6, 8, 10%). Test results show that 4~8% anhydrite concrete have improved engineering properties (hydration, compressive strength, shrinkage, creep, carbonation) as control concrete at early ages.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.524-529
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• 2020

To increase the mechanical durability of the proton exchange membrane fuel cells, a reinforced membrane in which a support is placed in the polymer membrane is used. The support mainly uses e-PTFE, which is hydrophobic and does not transfer ions, which may cause performance degradation. In this study, we investigated the effect of e-PTFE support on PEMFC performance and electrochemical durability. In this study, the reinforced membrane with the support was compared with the single membrane (non-reinforced membrane). Due to the hydrophobicity of the support, the water diffusion coefficient of the reinforced membrane was lower than that of the single membrane. The reinforced membrane had a lower water diffusion coefficient, resulting in higher HFR, which is the membrane migration resistance of ions, than that of a single membrane. Due to the low hydrogen permeability of the support, the OCV of the reinforced membrane was higher than that of the single membrane. The support was shown to reduce the hydrogen permeability, thereby reducing the rate of radical generation, thereby improving the electrochemical durability of the reinforced membrane.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.19-25
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• 2023

Although a lot of research and development has been conducted on the performance improvement of PEM (Proton Exchange Membrane) water electrolysis, the research on durability is still in early stage. This study investigated effect of temperature on the water electrolysis durability when driving temperature of the PEM water electrolysis was increased to improve performance. Voltage change, I-V, CV (Cyclic Voltammetry), LSV (Linear Sweep Voltammetry), Impedance, and FER (Fluoride Emission Rate) were measured while driving under a constant current condition in a temperature range of 50~80 ℃. As the operating temperature increased, the degradation rate increased. At 50~65 ℃, the degradation of the IrO₂ electrocatalyst mainly affected the durability of the PEM water electrolysis cell. At 80 ℃, the polymer membrane and electrode degradation proceeded similarly, and the short resistance decreased to 1.0 kΩ·cm² or less, and the performance decreased to about 1/3 of the initial stage after 144 hours of operation due to the shorting phenomenon.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.144-151
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• 2023

In this study, a database was established by collecting experimental results on various concrete mixtures subjected to freeze-thaw cycles, based on which an artificial neural network-based prediction model was developed to estimate durability resistance of concrete. A regression analysis was also conducted to derive an equation for estimating relative dynamic modulus of elasticity subjected to freeze-thaw loads. The error rate and coefficient of determination of the proposed artificial neural network model were approximately 11% and 0.72, respectively, and the regression equation also provided very similar accuracy. Thus, it is considered that the proposed artificial neural network model and regression equation can be used for estimating relative dynamic modulus of elasticity for various concrete mixtures subjected to freeze-thaw loads.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.345-348
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• 2005

본 개발의 목적은 연료전지차량에 탑재되는 연료전지 시스템에 장착될 공기공급기를 개발하는 것이었다. 개발된 공기공급기의 형태는 공급해야 할 공기의 유량과 압력 범위, 소음 및 향후 양산성 등을 고려하여 원심형 블로어를 선택하였으며, 차량 부하에 따른 공기공급량을 제어하기 위한 제어기도 적용되었다. 또한 차량에 적용될 경우, 예상되는 가혹한 사용환경에서 안정적인 성능을 발휘하고, 내구성을 할 수 있도록 설계되었으며, 특히, 외기온도 $45^{\circ}C$에서도 충분한 방열성능을 갖도록 모터 및 모터 방열구조를 설계하였다. 이를 위하여 공급되는 공기로 직접 모터를 냉각하는 개념을 적용하였다. 개발된 터보블로어의 응답성을 포함한 성능평가를 수행하였으며, 설계점에서 600시간 연속운전을 통하여 기본 내구평가를 완료하였다.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.52-56
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• 2004

Pd catalyst have been used in hydrogenation, oxidation, and low temperature combustion reaction. Recently, it is candidated as a possible reagents in the partial oxidation of methanol reformers of the fuel cell. Pd catalysts, even though it is very precious and expensive, catalytic functioning is good, but it still need to be improved in the matter of durability and low catalytic activity after calcination. In this study, we synthesize the improved Pd catalyst and study their chemical functioning.

• Journal of Applied Reliability
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• v.6 no.4
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• pp.307-315
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• 2006

차량 전장품 중 와이어링 하네스에서 큰 전류가 흐르는 회로의 연결 단자가 가지는 전기적 내구 성능 및 기계적 성능을 확보하기 위하여 단자 압착부의 압축율 최적화 기법을 개발하였다. 우선 단자 제작 과정을 표준화한 후 압착부의 주요 인자인 기계적 인장강도와 내부 부식 정도에 의한 전기적 저항 중대로 화재가 발생 가능성 관점에서 접근하였다. 여러 가지 실험을 통하여 얻어진 DATA를 분석한 결과 회귀 2차 모형을 사용하여 대전류 단자 압착부의 전기적/기계적 내구 성능 최적화 구간을 설정 하였으며, 이의 과정을 제시 하였다.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.106-106
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• 2012

막구조(Membrane structure)란 건축분야에서 "fabric structure" 또는 tension structure"와 같이 사용되는 용어로 코팅된 직물(coated fabrics)을 주재료로 사용하는 구조를 말한다. 특히 구조체로서 연성의 막을 이용 이것에 초기 장력을 주어 강성을 늘림으로서 외부하중에 대하여 안정된 형태를 유지하는 장점을 갖고 있다. 초기 창안된 독일의 온화한 기후에 적용되는 반면 한국이나 일본에는 60m/sec를 넘나드는 태풍의 피해와 많은 적설량을 보이는 기후적 제약으로 발달되지 못하였다. 그러나 최근 새로운 소재의 막구조 제품 개발과 구조해석 방법 및 시공기술 등이 개발되어 보편화되어지고 있는 실정이다. 막구조용 재료로 사용되는 섬유소재는 주로 Polyester직물을 기재로 한 PVC 코팅 제품으로 일반 PVC 막재는 장력이 약하고, 광선에 의한 물성이 쉽게 변화되어 내구연한이 5~15년에 불과하다. 유리섬유나 아라미드섬유 등으로 제직한 기재에 고내열 실리콘이나 PTFE 수지를 코팅한 제품은 약품에 대한 내구성이 높고 자외선에 대해서는 매우 큰 저항성을 가지기 때문에 내구연한이 10년에서 30년 까지도 향상된다. 그러나 실리콘 코팅막은 세계적으로 가장 좋은 막재로 알려졌으나 자정능력(Self Cleaning)에 문제가 발생되어 사용량이 감소 추세라고 할 수 있다. 일반적인 코팅 가공의 경우 MEK, Toluene, DMF 등과 같은 유기용제를 다량 사용함에 따라 작업환경 및 대기오염, 화재 위험 등의 문제점이 있으며 특히 가공시 잔류되는 유기용제의 심각성이 대두되고 있는 상황이다. 이와 같이 코팅 가공제 자체를 친환경적인 물질로 대체하여 각종 환경규제에 대응하고 유해 폐기물의 발생을 줄일 수 있는 코팅 가공제 및 가공기술 개발이 절실하다. 이에 본 연구에서는 Glass-Fiber, Aramid 등의 슈퍼 섬유와 고 강력 섬유 등을 이용하여 PTFE 코팅제품과 비슷한 수준의 성능을 부여하는 무용제형 실리콘 코팅 수지를 개발하고 내구성능 향상, Self Cleaning성, 난연성, 자외선 차단, 인장강도 및 인열 강도의 향상 등 다양한 기능성을 부여하는 최적의 환경 친화적 코팅 공정 기술을 개발하여 차세대 건축용 막구조 제품을 개발하고자 한다.

• Fire Science and Engineering
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• v.23 no.1
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• pp.40-47
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• 2009

Applying fire resistive coating to steel members is one of the general methods to secure fire resistance performance of steel members. And intumescent coating system is currently one of methods giving fire resistance to steel members. Intumescent coating system for fire resistance, however, has undesirable weaknesses that fire resistance performance of steel members is being deteriorated due to cracks and falling-offs of the coverings as time goes after completion of the coverings to the members. So it is necessary to understand changes of the durability and the fire resistance performance of intumescent coating system over a time elapse and to reflect such change properly into the building design and construction. This research is performed to present the test method of durability and the maintenance of intumescent coating system through theoretical investigation of the test method of durability and the guide of maintenance & management of intumescent coating system of several countries, including the Britain, United States, Japan.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.561-564
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• 2008

Concrete scaling is the progressive surface deterioration of susceptible subjected to freeze-thaw cycling in the presence of moisture. Particularly, it has been recognized that chlorides present in deicing agents can significantly increase concrete surface scaling. Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Use of deicing chemicals has been and will continue to be a major part of highway snow and ice control methods. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. Extensive use of chloride deicers is, however, not only the source of substantial cost penalties due to their corrosive action and ability to deterioration roadway surface materials but also the source of environmental damages. In this study, Use of (40, 27, 21MPa) pavement concrete analyze freeze-thaw test and scaling on the chlorides present.