• 한국지반환경공학회 논문집
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• 제21권12호
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• pp.35-41
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• 2020

도심지의 건축구조물 밀집 및 아파트 재건축 등으로 인하여 지하공간 개발이 다양하게 이루어지고 있으나, 차수 및 지반보강작업에 있어 부등침하와 같은 다양한 문제들이 발생하고 있다. 지반 보강에 있어 빈번히 사용되고 있는 그라우팅 공법에서는 시공단계에서 투입된 그라우트 재의 주입량 측정 또는 지반 보링 후 일축압축강도시험을 통해 품질관리를 수행하고 있으나, 시공단계에서 지반 보강이 제대로 이루어졌는지는 판단하기 어려운 실정이다. 이러한 문제를 해결하기 위해 전도성 재료가 혼합된 그라우트 재를 사용하여 그라우팅을 수행한 후 전기비저항 측정을 통해 품질관리를 수행하기 위한 연구가 필요한 실정이다. 본 연구는 이에 대한 기초연구로 전도성 재료인 탄소섬유가 혼합된 그라우트 재의 성능을 평가하기 위해 탄소섬유가 0%, 3%, 5%, 7%로 혼합된 시멘트 공시체를 제작하였으며. 제작한 공시체에 대하여 7일, 14일, 28일 수중양생 시킨 후 1%/min의 변형속도로 일축압축시험을 수행하였다. 일축압축시험 결과 탄소섬유의 배합비 증가에 따라 일축압축강도가 증가하는 경향을 보였으며, 혼합된 탄소섬유가 그라우트재의 조기강도 발현에 영향을 미치는 것을 확인하였다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.387-392
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• 2018

Various technical approaches and concepts have been proposed to develop conductive super-hydrophobic (SH) surfaces. However, most of these approaches are not usable in practical applications because of insufficient adhesion and cost issues. Additionally, durability and uniformity issues are still in need of improvement. The goal of this research is to produce a large-area conductive SH surface with improved adhesion performance and uniformity. To this end, carbon nanotubes (CNT) with a high aspect ratio and elastomeric polymer were utilized as a conductive filler and matrix, respectively, to form a coating layer. Additionally, nanoscale silica particles were utilized for stable implementation of the conductive SH surface. To improve the adhesion properties between the SH coating layer and substrate, pretreatment of the substrate was conducted by utilizing both wet and dry etching processes to create specific organic functional groups on the substrate. Following pretreatment of the surface, a zirco-aluminate coupling agent was utilized to enhance adhesion properties between the substrate and the SH coating layer. Raman spectroscopy revealed that adhesion was greatly improved by the formation of a chemical bond between the substrate and the SH coating layer at an optimal coupling agent concentration. The developed conductive SH coating attained a high electromagnetic interference (EMI) shielding effectiveness, which is advantageous in self-cleaning EMI shielding applications.

• 한국해양공학회지
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• 제23권3호
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• pp.35-39
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• 2009

The main objective of this study was to investigate fiber reinforced composite materials (FRCM) with electromagnetic shielding characteristics using aluminum (Al) film and copper (Cu) meshes. This study investigated the electromagnetic interference (EMI) shielding effectiveness (SE) of fiber reinforced composites filled with Al film, Cu meshes, and nano carbon black as hybrid conductive fillers to provide the electromagnetic shielding property of the fiber reinforced composites. The coaxial transmission line method of ASTM D 4935-89 was used to measure the EMI shielding effectiveness of composites in the frequency range of 300 MHz to 1.5 GHz. The variations of SE of FRCM with Al film, fine Cu, and general Cu meshes are described. The results indicate that the FRCM having Al film exhibited up to 75 dB of SE at 1.5 GHz.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.399-407
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• 2006

In this study, an electrical conductive carbon fiber was used as a biofilter matrix to electrochemically improve the biofilter function. A bioreactor system was composed of carbon fiber (anode), titanium ring, porcelain ring, inorganic nutrient reservoir, and VOC reservoir. Electric DC power of 1.5 volt was charged to the carbon fiber anode (CFA) to induce the electrochemical oxidation potential on the biofilter matrix, but not to the carbon fiber (CF). We tested the effects of electrochemical oxidation potential charged to the CFA on the biofilm structure, the bacterial growth, and the activity for metabolic oxidation of VOCs to $CO_2$, According to the SEM image, the biofilm structure developed in the CFA appeared to be greatly different from that in the CF. The bacterial growth, VOCs degradation, and metabolic oxidation of VOCs to $CO_2$ in the CFA were more activated than those in the CF. On the basis of these results, we propose that the biofilm structure can be improved, and the bacterial growth and the bacterial oxidation activity of VOCs can be activated by the electrochemical oxidation potential charged to a biofilter matrix.

• 대한기계학회논문집A
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• 제32권11호
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• pp.918-923
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• 2008

Since crack detection for laminated composites in-service is effective to improve the structural reliability of laminated composites, it have been tried to detect cracks of laminated composites by various nondestructive methods. An electric potential method is one of the widely used approaches for detection of cracks for carbon fiber composites, since the electric potential method adopts the electric conductive carbon fibers as reinforcements and sensors and the adoption of carbon fibers as sensors does not bring strength reduction induced by embedding sensors into the structures such as optical fibers. However, the application of the electric method is limited only to electrically conductive composite materials. Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints because it can monitor continuously the damage of adhesively bonded structures without producing any defects. Polymeric materials for the matrix of composite materials have piezoelectric characteristics similarly to adhesive materials, and the fracture of composite materials should lead to the fracture of polymeric matrix. Therefore, it seems to be valid that the piezoelectric method can be applied to monitoring the damage of composite materials. In this research, therefore, the feasibility study of the damage monitoring for composite materials by piezoelectric method was conducted. Using carbon fiber epoxy composite and glass fiber composite, charge output signals were measured and analyzed during the static and fatigue tests, and the effect of fiber materials on the damage monitoring of composite materials by the piezoelectric method was investigated.

• 한국구조물진단유지관리공학회 논문집
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• 제28권3호
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• pp.47-58
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• 2024

본 연구에서는 마이크로 강섬유와 다중벽 탄소나노튜브(multi-walled carbon nanotube, MWCNT)를 혼입한 전도성 모르타르의 발열성능, 휨강도 및 미세구조를 분석하기 위해 실험적으로 수행하였다. 전도성 모르타르 발열성능 및 휨강도 시험에서 MWCNT의 혼입 농도는 시멘트 중량 대비 0.0wt%, 0.5wt% 및 1.0wt%로 선정하였으며, 마이크로 강섬유는 부피 대비 2.0vol%로 혼입하였다. 발열성능 실험은 다양한 인가전압 (DC 10V, 30V, 60V) 및 상이한 전극간격 (40 mm, 120 mm)을 매개변수로 수행하였으며, 양생 재령 28일에서 휨강도를 측정하여 일반 모르타르와 비교, 분석하였다. 더 나아가, 전계방사 주사전자현미경(field emission scanning electron microscope, FE-SEM)을 이용하여 전도성 모르타르의 표면 형상과 미세구조를 분석하였다. 그 결과 MWCNT의 혼입 농도와 인가전압이 증가할수록 발열성능이 향상되었으며, 전극간격이 좁을수록 발열성능이 더욱 향상되는 것으로 나타났다. 하지만 MWCNT의 혼입 농도를 1.0wt%까지 추가하더라도 발열성능은 크게 향상되지 못하였다. 휨강도 시험결과, PM 시편과 MWCNT를 혼입한 시편을 제외한 모든 시편의 평균 휨강도가 4.5 MPa 이상으로 나타나 마이크로 강섬유 혼입에 따른 높은 휨강도를 보였다. FE-SEM 이미지 분석을 통해 시멘트 매트릭스 내 마이크로 강섬유와 MWCNT 입자 사이에 전도성 네트워크가 형성되는 것을 확인하였다.

• 한국레이저가공학회지
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• 제12권4호
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• pp.6-11
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• 2009

The LDS(Laser Direct Structuring) process uses thermoplastic polymers with a additive compound that serves as plating seed after the activation by laser. It can realize industry requirement such as miniaturization of electrical component, design flexibility and reduction of production steps. The purpose of this study is to introduce LDS, and to investigate the fundamental mechanism. Also the characteristics of conductive patterns were investigated with respect to laser fluence and intensity. We have used a pulsed fiber laser (wavelength : 1064nm) and copper electroless plating to fabricate conductive patterns. The result showed that laser induced metal-organic complex was caused metalization by electroless copper plating, the critical laser fluence was $1.41\;J/cm^2$ at a scan speed of 1 m/s.

• 폴리머
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• 제25권2호
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• pp.293-301
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• 2001

새로운 복합재료 제조 기술인 electron-ion technology (EIT)를 이용하여 전도성 탄소섬유/고밀도 폴리에틸렌 (CF/HDPE) 복합필름을 제조하고 탄소섬유 에폭시 sizing이 제조된 필름의 체적비저항과 인장강도 그리고 계면 특성에 미치는 영향에 대하여 연구하였다. 에폭시 sizing은 tunneling 효과를 좋게 해서 복합재료 필름의 전도성을 향상시키는 반면, 극성인 에폭시 sizing은 무극성인 폴리에틸렌과의 친화성이 없어서 탄소섬유와 폴리에틸렌간의 계면결합력을 감소시키므로 에폭시 sized 탄소섬유(CF(S))는 unsized 탄소섬유(CF(U))에 비하여 필름의 체적비저항과 인장강도를 감소시켰다. 에폭시 sizing은 탄소섬유의 nucleating efficiency를 떨어뜨려서 CF(S)/HDPE 필름이 CF(U)/HDPE 필름보다 불규칙적이고 덜 발달된 transcrystalline layer를 형성함을 관찰할 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제9권4호
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• pp.330-338
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• 2018

The adhesion strength as well as the electrochemical properties of $LiNi_{0.4}Mn_{0.4}Co_{0.2}O_2$ electrodes containing various conductive carbons (CC) such as fiber-like carbon, vapor-grown carbon fiber, carbon nanotubes, particle-like carbon, Super P, and Ketjen black is compared. The morphological properties is investigated using scanning electron microscope to reveal the interaction between the different CC and the active material. The surface and interfacial cutting analysis system is also used to measure the adhesion strength between the aluminum current collector and the composite film, and the adhesion strength between the active material and the CC of the electrodes. The results obtained from the measured adhesion strength points to the fact that the structure and the particle size of CC additives have tremendous influence on the binding property of the composite electrodes, and this in turn affects the electrochemical property of the configured electrodes.

• 패션비즈니스
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• 제25권1호
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• pp.51-64
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• 2021

The purpose of this study was to develop smart bags that combining fashion-specific trends and smart information technologies such as light-emitting diodes(LED) and optic fibers by grafting marquage techniques that have recently become popular as part of eco-fashion. We applied e-textiles by designing leather tote bags that could show off LED luminescence. A total of two tote bags, a white-colored peacock design and a black-colored paisley design, divided the LED's light-emitting method into two types, incremental lighting and random light-emission to suit each design, and the locations of the optical fibers were also reversed depending upon the design. The production of circuits for the LEDs and optical fibers was based on the design, and a flexible conductive fabric was laser-cut instead of wire line and attached to the circuit-line location. A separate connector was underwent three-dimensional(3D)-modeling and was connected to high-luminosity LEDs and optic fiber bundles. The optical fiber logo part expressed a subtle image using a white-colored LED, which did not offset the LED's sharp luminous effects, suggesting that using LEDs with fiber optics allowed for the expression of each in harmony without being heterogeneous. Overall, the LEDs and fiber optic fabric were well-harmonized in the fashion bag using marquage techniques, and there was no sense of it being a mechanical device. Also, the circuit part was made of conductive fabric, which is an e-textile product that feels the same as a thin, flexible fabric. The study confirmed that the bag was developed as a smart wearable product that could be used in everyday life.