• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.83-84
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• 2018

3D printing technology can be applied to various industries, and is trapped by major technologies that change existing manufacturing processes. 3D printing materials must satisfy designability, economy and productivity, and building materials are required to have strength and economy secured technology. 3D printing technology of construction field can be divided into structural materials and internal and external materials, and is mainly done by extruding and adapting. Particularly when it is applied as an exterior materials, it is mainly applied to an unstructured exterior materials and high accuracy is required. The exterior materials can be used as a cement composite materials, it is suitable also for a lamination type, and the role of a cement base bonding material is important. In this research, we developed a cementitious base binder applicable as a 3D printing exterior materials, confirmed density and strength characteristics for application as an exterior materials, a flame retardancy test for improving the fire resistance of buildings and confirmed its possibility.

• 센서학회지
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• 제16권6호
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• pp.407-412
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• 2007

For $VO_{2}$ sensors applicable to temperature measurement by using the nature of semiconductor to metal transition, the crystallinity, microstructure, and temperature vs. resistance characteristics were investigated systematically as a function of the annealing condition. The starting materials, vanadium pentoxide ($V_{2}O_{5}$) powders, were mixed with vehicle to form paste. This paste was screen-printed on $Al_{2}O_{3}$ substrates and then $VO_{2}$ thick films were heat-treated at $450^{\circ}C$ to $600^{\circ}C$, respectively, for 1 hr in $N_{2}$ gas atmosphere for the reduction. As results of the temperature vs. resistance property measurements, the electrical resistance of the $V_{2}O_{5}$ sensor in phase transition range was decreased by $10^{3.9}$ order. The presented critical temperature sensor could be used in fire-protection and control systems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.277-283
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• 2004

The time to ignition, heat release rate characteristics and carbon monoxide yield of fiber reinforced and sandwich phenol resin were investigated with cone calorimeter. The fire characteristics of unsaturated polyester, mostly being applied to the existing passenger train, and phenolic resin were compared. Thermal gravimetric analysis(TGA) was used to monitor the degree of thermal decomposition for the phenolic resin. According to the cone calorimeter data, the time to ignition, heat release rate and CO yield was faster and higher as the external heat flux increase. Under the same heat flux, the time to ignition of sandwich type phenolic resin was shorter than that of fiber reinforced. The result of comparison between unsaturated polyester and phenolic resin was that phenolic resin was shown to have better fire resistance than that of unsaturated polyester.

• Steel and Composite Structures
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• 제30권2호
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• pp.141-147
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• 2019

Fire is one of the environmental parameters affecting the structure causing element internal forces to change, as well as reducing the strength of the materials. One of the common types of floors in tall steel structures is the steel concrete composite slab. Shear connectors are used in steel and concrete composite beam in various shapes also has played significant role in a burning fire event of building with a steel concrete composite beam. The current study has reviewed the effects of temperature raising on the angle connector behavior through the use of push out tests and monotonic static force. The results have shown (1) the ductility of the samples is acceptable based on EC4 standard; (2) temperature raising has reduced the stiffness; (3) the shear ductility increment; and (4) the shear capacity reduction. Also, the amount of angle shear connector resistance has been decreased from 18.5% to 41% at ambient temperature up to $850^{\circ}C$.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.140-141
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• 2020

Concrete has a lower thermal conductivity or thermal diffusion coefficient compared to other building materials, so it is widely used as fireproof compartment material or refractory material for structures. However, in the event of thermal damage such as fire, cement curing agents and aggregates act differently, resulting in heat generation or deterioration of tissue due to dehydration, resulting in deterioration of physical properties and fire resistance. Therefore, in this study, the processing structure of cement paste is measured through nitrogen absorption method. The test specimen is a cement paste of 40% W/C and is set at 1000 ℃ under heating temperature conditions. As the temperature rose, the micro-pore mass below was reduced based on about 0.01 감소m, but the air gap above that was increased.Thus, in the range of pores measured in nitrogen adsorption, the air mass tended to decrease under high temperature conditions.

• 콘크리트학회논문집
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• 제17권2호
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• pp.247-254
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• 2005

일반적으로 콘크리트는 다른 구조재료에 비해서 우수한 내화성능을 가지고 있기 때문에 내화구조 또는 방화구조 재료로 널리 사용되고 있으나, 화재시 가열에 의해 열응력과 열변형에 의한 손상뿐 아니라 폭렬현상과 같은 국부적인 파괴가 일어나게 된다. 따라서 이를 보완하기 위한 여러 연구가 진행되어지고 있다. 또한 최근, 첨단 나노기술은 일반적인 재료들과 다른 독특한 물리적, 화학적 특성을 갖도록 개발되고 있다. 나노 $SiO_2$가 혼입된 콘크리트의 내부온도, 중량손실률 및 압축강도 특성을 비교$\cdot$검토하여 높은 응력의 내화와 낮은 열적 거동의 증진을 연구하였다. 본 연구에서는 나노입자가 시멘트 중량의 0, 2, 4, $6\%$ 포함된 시편 (${\Phi}100{\times}200 mm$)과 화력 온도 $200^{\circ}C$, $500^{\circ}C$, $800^{\circ}C$에서 실험을 수행하였다. 그 결과 나노 입자 혼입률이 증가할수록 화력을 가한 후의 콘크리트 중량 손실률은 점차 감소하고, 압축, 강도는 효과적으로 증가하였다. 따라서 고온에서의 물리적 역학적 실험결과 강도 및 내부온도 증가면에서는 보통 콘크리트와 비교하여 충분히 건설용 구조재료로서의 사용이 가능할 것으로 판단된다.

• 한국건설순환자원학회논문집
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• 제3권4호
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• pp.328-334
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• 2015

건축용 단열재는 에너지 절약을 목적으로 적용되며 불연 및 내화성능이 요구되는 부위는 무기계 섬유를 주재료로 사용하는 미네랄울 및 글라스울 소재가 적용된다. 하지만 무기계 소재인 미네랄울이나 글라스울은 특성상 수분에 취약하여 뭉침 및 처짐 현상 등이 발생하여 단열효과가 떨어지며 유기계 소재인 폴리스티렌폼이나 우레탄폼 등은 화재에 취약하고 일산화탄소 발생에 의한 가스유해성 등으로 적용에 한계를 갖고 있다. 본 연구에서는 폐유리분말과 플라이애시를 사용하여 가볍고 열전도율이 낮은 무기계 경량 발포소재를 제조하고 물리적 특성을 분석하여 단열용 제품으로서의 가능성을 확인하고자 하였다. 연구결과 폐유리분말과 플라이애시를 사용한 경량 발포소재는 균일한 공극을 형성하며 발포하였고 경량이며 불연재료이므로 불연성능 요구되는 부위에 사용이 가능하다.

• Coupled systems mechanics
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• 제6권3호
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• pp.335-349
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• 2017

To cope with the demand on giant and durable buildings, reinforcement of concrete is a practical problem being extensively investigated in the civil engineering field. Among various reinforcing techniques, fiber-reinforced concrete (FRC) has been proven to be an effective approach. In practice, such fibers include steel fibers, polyvinyl alcohol (PVA) fibers, polyacrylonitrile (PAN) carbon fibers and asbestos fibers, with the length scale ranging from centimeters to micrometers. When advancing such technique down to the nanoscale, it is noticed that carbon nanotubes (CNTs) are stronger than other fibers and can provide a better reinforcement to concrete. In the last decade, CNT-reinforced concrete attracts a lot of attentions in research. Despite high cost of CNTs at present, the growing availability of carbon materials might push the usage of CNTs into practice in the near future, making the reinforcement technique of great potential. A review of existing research works may constitute a conclusive reference and facilitate further developments. In reference to the recent experimental works, this paper reports some key evaluations on CNT-reinforced cementitious materials, covering FRC mechanism, CNT dispersion, CNT-cement structures, mechanical properties and fire safety. Emphasis is placed on the interplay between CNTs and calcium silicate hydrate (C-S-H) at the nanoscale. The relationship between the CNTs-cement structures and the mechanical enhancement, especially at a high-temperature condition, is discussed based on molecular dynamics simulations. After concluding remarks, challenges to improve the CNTs reinforcement technique are proposed.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2866-2877
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• 2021

The complex coupling relationship between liquid sodium and concrete materials affects both the sodium fire characteristics and concrete properties through heat and chemical erosion. In this study, experiments on direct and indirect (separated by a steel plate) contact of the columnar sodium fire with the concrete surface were performed. It was found that the combustion efficiency of liquid sodium in direct contact with concrete was significantly enhanced and accompanied by intermittent explosions and splashing of small concrete fragments. The sodium fire on the surface of the concrete considerably increased the internal temperature, pore size, and distribution density of the concrete. In addition, the depth of influence on the loosening of the concrete structure was also greatly extended. The contact of liquid sodium with the concrete substantially affected its permeability resistance. The water absorption of the concrete surface was increased by more than 70% when liquid sodium directly impacted the bare concrete surface. However, the change in water absorption in the centre of the concrete was primarily affected by the duration of the external heat.

• 한국건축시공학회지
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• 제14권2호
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• pp.127-134
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• 2014

본 연구는 경량 무기 발포보드를 이용한 커튼월시스템의 시공성 및 경제성 분석에 관한 연구로, 내화성 경량 무기 발포보드는 커튼월의 백패널로 이용하기 위해 개발된 신소재로 내화성능은 선행연구를 통해 실물 내화시험을 실시하여 이미 분석한 바 있다. 본 연구에서는 실제 건물에 내화성 커튼월 시스템을 설치하여 Mock-up test를 수행하고 일반적인 커튼월 시스템과 비교 검토하였다. 이 시스템은 기존의 커튼월 시스템과 동일한 방법으로 시공되는데, 다만 내화성능 확보를 위해 공장에서 제단되어 온 경량무기 발포보드 사용하고, 이를 커튼월 프레임에 취부한다. 비록 기존 커튼월 대비 프레임에 부착해야하는 추가 작업이 발생하나, 경량 무기 발포보드를 이용한 백패널은 커팅만으로 제작이 간편하고, 분진발생이 없어 인체에 무해하며, 파손여부를 바로 확인할 수 있어 품질확보가 용이하다. 따라서 이 시스템은 높은 수준의 내화성을 확보하면서도 시공성과 경제성면에서도 기존 커튼월 시스템과 동등이상임으로 판단된다.