This research studied the electrical characteristics, IR transmission characteristics, stealth functions, and thermal characteristics of infrared thermal-imaging cameras of copper-sputtered samples. Nylon samples were prepared for each density as a base material for copper-sputtering treatment. Copper-sputtered NFi, NM1, NM2, NM3, NM4, and NM5, showed electrical resistance of 0.8, 445.7, 80.7, 29.7, 0.3, and 2.2 Ω, respectively, all of which are very low values; for the mesh sample, the lower the density, the lower the electrical resistance. Measuring the IR transmittance showed that the infrared transmittance of the copper-sputtered samples was significantly reduced compared to the untreated sample. Compared to the untreated samples, the transmittance went from 92.0–64.1%. When copper sputtered surface was directed to the IR irradiator, the IR transmittance went from 73.5 to 43.8%. As the density of the sample increased, the transmittance tended to decreased. After the infrared thermal imaging, the absolute values of △R, △G, and △B of the copper phase increased from 2 to 167, 98 to 192, and 7 to 118, respectively, and the closer the density of the sample (NM5→NFi), the larger the absolute value. This proves that the dense copper phase-up sample has a stealth effect on the infrared thermal imaging camera. It is believed that the copper-sputtered nylon samples produced in this study have applications in multifunctional uniforms, bio-signal detection sensors, stage costumes, etc.
This study produces electroconductive polycaprolactone (PCL)-based film with different amounts of graphene (G) through electrospinning, and the characteristics of the produced G/PCL composites are investigated. The G/PCL results are analyzed by comparing them with those obtained using pure PCL electrospun film as a control. The morphology of electrospun material is analyzed through scanning electron microscopy and transmission electron microscopy. Mechanical and electrical properties are also evaluated. Composites containing 1% graphene have the highest elongation rate, and 5% samples have the highest strength and elasticity. Graphene contents > 25% show electro-conductivity, which level improves with increase of graphene content. Biological characteristics of G/PCL composites are assessed through behavioral analysis of neural cell attachment and proliferation. Cell experiments reveal that compositions < 50% show slightly reduced cell viability. Moreover, graphene combinations facilitated cell proliferation compared to pure PCL. These results confirm that a 25 % G/PCL composition is best for application to systems that introduce external stimuli such as electric fields and electrodes to lead to synergistic efficiency of tissue regeneration.
Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of 150℃. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.
The slow diffusion of pollutants to the surface of electrodes has limited the contact between OH radicals and micropollutants in electro-oxidation processes. In this study, conductive hollow fiber membrane (CHF) made with multi-walled carbon nanotube (CHF) was fabricated and operated with flow-through system. During the electro-oxidation of three micropollutants, a conventional flow-by reactor showed less than 60% of removals at the hydraulic retention time (HRT) of 30 minutes, while flow-through operation could achieve complete removal for all tested micropollutants at the same HRT. Moreover, the flow-through system exhibited complete removals even at the HRT of 1 minutes, while that of flow-by system were less than 10 %.
In recent years, solar cells based on crystalline silicon(c-Si) have accounted for much of the photovoltaic industry. The recent studies have focused on fabricating c-Si solar modules with low cost and improved efficiency. Among many suggested methods, a photovoltaic module with a shingled structure that is connected to a small cut cell in series is a recent strong candidate for low-cost, high efficiency energy harvesting systems. The shingled structure increases the efficiency compared to the module with 6 inch full cells by minimizing optical and electrical losses. In this study, we propoese a new Conductive Paste (CP) to interconnect cells in a shingled module and compare it with the Electrical Conductive Adhesives (ECA) in the conventional module. Since the CP consists of a compound of tin and bismuth, the module is more economical than the module with ECA, which contains silver. Moreover, the melting point of CP is below 150 ℃, so the cells can be integrated with decreased thermal-mechanical stress. The output of the shingled PV module connected by CP is the same as that of the module with ECA. In addition, electroluminescence (EL) analysis indicates that the introduction of CP does not provoke additional cracks. Furthermore, the CP soldering connects cells without increasing ohmic losses. Thus, this study confirms that interconnection with CP can integrate cells with reduced cost in shingled c-Si PV modules.
최근 대두된 난분해성 미량오염물질은 일반적인 수처리 공법으로는 제거가 잘 되지 않고 수 ng/L 단위로도 수중생태계와 인간에게 독성을 나타내므로 반드시 처리가 필요하다. 따라서 본 연구에서는 CNT (Carbon nanotube)를 이용하여 중공사막을 제조한 후, 그것을 전극으로 사용하여 미량오염물질을 전기화학적으로 산화 제거하였다. SEM, BET, flux, conductivity 결과를 통해 전극의 특성을 분석하였다. BPA(bisphenol A), Sulfamethoxazole(SMX), N,N-Diethyl-metatoluamide(DEET) 3가지 물질을 제거 대상 미량오염물질로 선정하였고 CHM 산화극 내부로 오염물질이 포함된 물을 흘려 보내주었을 때 5분 만에 100%의 제거효율을 보였다.
Noncontact direct-printed conductive silver patterns with an enhanced electrical resistivity are fabricated using a silver ink with a mixture of silver nanoparticles and nanoplates. The microstructure and electrical resistivity of the silver pattern are systematically investigated as a function of the mixing ratio of the nanoparticles and nanoplates. The pattern, which is fabricated using a mixture with a mixing ratio of 3(nanoparticles):7(nanoplates) and sintered at 200oC shows a highly dense and well-sintered microstructure and has a resistivity of 7.60 μΩ·cm. This originates a mutual synergistic effect through a combination of the sinterability of the nanoparticles and the packing ability of the nanoplates. This is a conductive material that can be used to fabricate noncontact direct-printed conductive patterns with excellent electrical conductivity for various flexible electronics applications, including solar cells, displays, RFIDs, and sensors.
Perfluorinated sulfonic acid (PFSA) ionomers have been widely used for renewable energy generation, including polymer electrolyte fuel cells (PEFCs), owing to their excellent resistance to harsh chemicals and good ion-transport properties. PFSA materials experience critical chemical decomposition to radical attacks, and fast hydrogen crossover leading to fairly reduced electrochemical performances, when they are used as membrane materials. Similar chemical degradation also occurs in PEFC electrodes containing PFSA ionomer binders used as both mechanical supporters and proton conductors and shortens PEFC lifetime. In this study, several approaches based on their morphological rearrangement to overcome these economical and technical issues are proposed. They include pore-filling membrane formation, nanodispersion, and their combination.
The conductive polymer composites have attracted considerable attention in the field of industry due to their electrical properties. To understand electrical properties of the composites, their volume specific resistance was measured. Electrical conductivity results showed percolation phenomena. Percolation theories are frequently applied to describe the insulator-to-conductor transitions in the composites composed of conductive filler and insulating matrix. It was found that the percolation threshold strongly depends on the aspect ratio of filler particles. The critical concentration of percolation formed is defined as the percolation threshold. The purpose of this study was to examine electrical properties of the epoxy resins filled with nickel. The sample was prepared using vehicle such as epoxy resin replenished with nickel powder, and the evaluation on their practical use was performed in order to apply them to electric and electronic industry as well as general field. The volume specific resistance of epoxy resin composites was 4.666~13.074 when using nickel powder. Weight loss of the conductive composites took place at 350℃~470℃.
The automotive industry is moving from the internal combustion engine to electric drive motors. Electricmotors uses a high voltage system requiring the development of resources and components to shield the system. There-fore, in this study, we analyze electromagnetic interference (EMI) shielding effectiveness (SE) characteristics of an autocrash pad according to the ratio of electrically conductive materials and propylene. In order to combine good mechan-ical characteristics and electromagnetic shielding of the automotive crash pad, metal-coated glass fiber (MGF) manufac-turing methods are introduced and compared with powder-type methods. Through this study, among MGF methods, wesuggest that the chopping method is the most effective shielding method.
The conductive polymer composites recently became increasingly to many fields of industry due to their electrical properties. To understand these properties of composites, electrical properties were measured and were studied relatively. Electrical conductivity measurements showed percolation phenomena. Percolation theories are frequently applied to describe the insulator-to-conductor transitions in composites made of a conductive filler and an insulating matrix. It has been showed both experimentally and theoretically that the percolation threshold strongly depends on the aspect ratio of filler particles. The critical concentration of percolation formed is defined as the percolation threshold. This paper was to study epoxy resin filled with copper. The experiment was made with vehicle such as epoxy resin replenished with copper powder and the study about their practical use was performed in order to apply to electric and electronic industry as well as general field. The volume specific resistance of epoxy resin composites was 3.065~13.325 in using copper powder. The weight loss of conductive composites happened from 350℃~470℃.
Polydimethylsiloxane(PDMS) 몰드를 사용한여소프트 리소그래피 방법을 통해 Poly(3-hexylthiophene)(P3HT)가 서브 파장(subwavelength) 사이즈로 나노패턴 된 전기 변색 소자를 제작하였다. 나노 패턴된 전기 변색 소자를 사용한여 착색 및 소색 상태에 따른 빛의 편광 효과를 패턴의 방향을 바꿔가며 측정하였으며, 인가전압에 따라 변화되는 고분자의 도핑 상태에 의해서 편광된 빛의 세기를 손쉽게 가역적으로 변화시킬 수 있었다. 편광 효율을 최댓값과 최솟값의 비로 정의하여 실험을 통해 1.7의 편광 효율값을 계산할 수 있었다. 산화, 환원 반응에 따른 고분자의 구조변화에 의해 도핑 상태에 따라 굴절률 차이가 생기게 되고 이에 따라 편광 된 빛의 세기를 인가전압의 스위칭만으로 조절할 수 있었다. 전기 변색 소자에 -2V와 2V 전압을 인가해 주었을 때 고분자 패턴과 전해질 사이의 굴절률 차이는 0.61과 0.99의 값으로 나타났다.
전도성 고분자 중 안정성이 높은 Poly(3,4-ethylenedioxythiophene) (PEDOT)을 이용하여 전기변색 박막을 제조하고 박막제조 방법에 따른 전기변색 특성을 연구하였다. PEDOT 박막은 전기중합법과 증기중합법에 의해 제조되었고, 두가지 방법 모두 도핑되지 않은 중성 상태에서 짙은 푸른색을 띠는 박막으로 제조되었다. 전기변색 특성을 평가하기 위하여 UV-Vis spectrophotometer와 Cyclic voltammetry가 사용되었으며, 산화/환원 시 표면은 AFM으로 관찰되었다. 전기 중합법으로 제조된 PEDOT 박막에 비해 증기중합에 방법에 의해 제작된 PEDOT 박막의 표면이 거칠기 50 nm 이내로 균일 하였다. 특히 증기 중합법을 이용하여 제조된 전기 변색 소재의 특성도 응답성 1.5초 이내, 49%의 투과율 차이, 402의 변색 효율을 보여 박막의 특성 향상으로 전기변색특성이 향상 된 결과를 보였다.
전기전자 및 디스플레이 산업에 다양한 응용이 기대되는 전도성 고분자인 PPP(Polyparaphenylene)는 단순한 구조와 비교적 높은 열적 안정성을 가지고 있으나 전기적 특성은 기존의 물질보다 낮아 그 응용이 더디게 진행되고 있다. 본 연구에서는 전도성 고분자의 전기적 특성을 개선하기 위해 이온주입법을 이용하여 전기전도성을 개선하는 연구를 진행하였다. 5keV에서 30keV 정도의 아주 낮은 에너지를 이용하여 이온을 가속시킴으로서 시편의 특성 열화를 최소화 할 수 있었다. 이온주입법으로 개선된 시편의 전기전도성은 향후 OTFT와 같은 Organic Electronics Device로서의 사용 가능성을 보였으며 이온의 종류와 주입정도에 따라 Thermoelectric power의 크기가 달라지는 반도체 소재로서의 특성을 나타내어 향후 다양한 형태의 소자에 응용될 수 있는 가능성을 확인하였다. 실험으로 확인된 최적의 이온주입에너지는 10keV에서 15keV의 값을 나타내었다.
The electrodes were fabricated by compounding the commercial activated carbons and additives of conducting polymer with PVdF mono binder and PVdF-PVP mixed binders. The best performance of the electrodes fabricated with activated carbon(BP-20) and PVdF-PVP mixed binders showed in 88wt. % BP-20. 7wt. % conducting polymer and 5wt.% PVdF-PVP mixed binder. The electrode exhibited excellent electrochemical characteristics having 8.16 W.h/kg of energy density, 34.77 F/g of specific capacitance, 0.67Ω of ESR.
A water-soluble conducting polymer (CPP400 Paste) containing a derivative of polythiophene with several dopant was investigated as an anode material for organic electroluminescent devices. The device of ITO/CPP 400 Paste/TPD/Alq3/Li:Al was fabricated, where CPP 400 Paste films were prepared by spin coating and TPD and Alq3, films were prepared by vacuum evaporation. It was found that the turn-on voltage, current density, and luminance of the devices were dependent upon the thickness of CPP 400 Paste film in the Electroluminescent and current-voltage characteristics of the devices. This phenomena were explained by the energy level diagram of the device with the energy levels of the CPP400 Paste obtained by cyclic voltammetric method.