Composite-based piezoelectric devices are extensively studied to develop sustainable power supply and selfpowered devices owing to their excellent mechanical durability and output performance. In this study, we design a leadfree piezoelectric nanocomposite utilizing (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) nanomaterials for realizing highly flexible energy harvesters. To improve the output performance of the devices, we incorporate porous BCTZ nanowires (NWs) into the nanoparticle (NP)-based piezoelectric nanocomposite. BCTZ NPs and NWs are synthesized through the solidstate reaction and sol-gel-based electrospinning, respectively; subsequently, they are dispersed inside a polyimide matrix. The output performance of the energy harvesters is measured using an optimized measurement system during repetitive mechanical deformation by varying the composition of the NPs and NWs. A nanocomposite-based energy harvester with 4:1 weight ratio generates the maximum open-circuit voltage and short-circuit current of 0.83 V and 0.28 A, respectively. In this study, self-powered devices are constructed with enhanced output performance by using piezoelectric energy harvesting for application in flexible and wearable devices.

본 연구에서는 공기중에서도 안정적이며 상대적으로 전기음성도가 큰 테플론계열의 고분자와 그래핀플라워를 이용하여 마찰전기 나노발전기를 제작하였다. 상기 복합고분자는 회전도포방법을 이용하 여 나노발전기의 전기적 음성층의 제작에 이용되었다. 전기적 양성층을 위하여 졸-겔 방법을 이용하여 산 화아연막을 제작하였다. 제작된 마찰전기 나노발전기는 약 44 μW의 최대전력을 생산하였다. 결론적으로, 마찰전기 나노발전기의 모든 활성층은 회전도포방법을 이용하였으므로 대면적으로 확장가능하다.

To develop a high capacity lithium secondary battery, a new approach to anode material synthesis is required, capable of producing an anode that exceeds the energy density limit of a carbon-based anode. This research synthesized carbon nano silicon composites as an anode material for a secondary battery using the RF thermal plasma method, which is an ecofriendly dry synthesis method. Prior to material synthesis, a silicon raw material was mixed at 10, 20, 30, 40, and 50 wt% based on the carbon raw material in a powder form, and the temperature change inside the reaction field depending on the applied plasma power was calculated. Information about the materials in the synthesized carbon nano silicon composites were confirmed through XRD analysis, showing carbon (86.7~52.6 %), silicon (7.2~36.2 %), and silicon carbide (6.1~11.2 %). Through FE-SEM analysis, it was confirmed that the silicon bonded to carbon was distributed at sizes of 100 nm or less. The bonding shape of the silicon nano particles bonded to carbon was observed through TEM analysis. The initial electrochemical charging/ discharging test for the 40 wt% silicon mixture showed excellent electrical characteristics of 1,517 mAh/g (91.9 %) and an irreversible capacity of 133 mAh/g (8.1 %).

In this study, using deep learning, super-resolution images of transmission electron microscope (TEM) images were generated for nanomaterial analysis. 1169 paired images with 256  256 pixels (high resolution: HR) from TEM measurements and 32  32 pixels (low resolution: LR) produced using the python module openCV were trained with deep learning models. The TEM images were related to DyVO4 nanomaterials synthesized by hydrothermal methods. Mean-absolute-error (MAE), peak-signal-to-noise-ratio (PSNR), and structural similarity (SSIM) were used as metrics to evaluate the performance of the models. First, a super-resolution image (SR) was obtained using the traditional interpolation method used in computer vision. In the SR image at low magnification, the shape of the nanomaterial improved. However, the SR images at medium and high magnification failed to show the characteristics of the lattice of the nanomaterials. Second, to obtain a SR image, the deep learning model includes a residual network which reduces the loss of spatial information in the convolutional process of obtaining a feature map. In the process of optimizing the deep learning model, it was confirmed that the performance of the model improved as the number of data increased. In addition, by optimizing the deep learning model using the loss function, including MAE and SSIM at the same time, improved results of the nanomaterial lattice in SR images were achieved at medium and high magnifications. The final proposed deep learning model used four residual blocks to obtain the characteristic map of the low-resolution image, and the super-resolution image was completed using Upsampling2D and the residual block three times.

본 연구에서는 유기용매용 나노여과막 (Organic Solvent Nanofiltration, OSN)의 유기용매 투과 및 분리성능을 분 석하였다. 비극성용매에 적합한 Puramem (PM) 시리즈 분리막의 소재를 분석한 후 다양한 유기용매 분위기에서의 투과성능 을 데드엔드셀로 측정하였다. PM 시리즈 분리막은 극성용매 대비 비극성용매에서 더 높은 투과도를 보였으며, 용질의 종류 및 분자량에 따라 매우 독특한 배제성능을 보이는 것을 확인하였다. 이는 기존 수처리에 적용되는 Solution-diffusion 투과모 델이 OSN 투과모델에는 적합하지 않다는 것을 알 수 있으며, solvent-solute-membrane 간의 상관관계를 더 정확하게 반영할 수 있는 새로운 인자가 필요하다는 결론을 낼 수 있다.

There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminumbased composites containing C60 fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

Indoor air contaminated with various pollutants commonly poses a risk to human health, and the need for installing air purifiers has been increasing. However, in commercial air purifiers pollutants-removal efficiency and durability are generally low. Since silver nano-composites are known to have catalytic oxidation and antibacterial capacities, it was anticipated to be applicable for indoor air purifiers. In this study, silver nano-composites were applied to granular activated carbon and scrubber solutions to treat a mixture of three air pollutants including toluene, formaldehyde, and bioaerosol. In the activated carbon deposited with silver nano-particles, the specific surface area decreased, resulting in a 10% loss of adsorption capacity for toluene. However, the removal efficacy of formaldehyde and bioaerosol increased by 10% due to the catalytic oxidation and antibacterial capacities. In the scrubber operation with silver nano-particles, the removal rates of formaldehyde and bioaerosol improved by 20%, while toluene removal was not observed. When the activated carbon column and the scrubber was connected in series, toluene was mainly removed by the activated carbon, and the removal rates of formaldehyde and bioaerosol increased in the presence of silver nano-particles. Consequently, for the improvement of indoor air quality, it is deemed appropriate to apply silver nano-material to indoor environments contaminated with pollutant mixtures.

고분자를 기반으로 하는 고체 전해질은 수퍼커패시터, 배터리, 센서, 액추에이터 등 다양한 전기화학 소자에 응용이 가능한 소재로써, 기존 고분자 전해질의 낮은 이온전도도를 향상시키기 위해서 다양한 이온성 액체 기반의 고체 전해질에 관한 연구가 활발히 진행 중에 있다. 이온성 액체의 높은 전기적 특성 및 전기화학적, 열적 안정성과 고분자의 우수한 기계적인 강도를 활용한 젤 상태의 고체 전해질인 이온젤은 차세대 웨어러블 및 플렉시블 전자소자에 응용되어 연구되고 있다. 따라서 본 연구에서는 이러한 이온성 액체와 고분자 기반의 고체 전해질을 제조하고 특성을 분석하여 탄소나노복합체 기반의 전극 에 적용하여 다양한 전자소자에 응용이 가능한 이온전도도 및 안정성이 향상된 이온성 액체 기반의 고체 전해질을 개발하고자 한다. 제조된 고체전해질은 전기화학적 임피던스법을 이용하여 이온 전도도를 측정 하여 보았으며 이온성 액체를 첨가하여 제조한 고체전해질의 이온 전도도가 1.26 x 10-1 S/cm 로 확인 되었다. 또한 제조된 고체 전해질을 이용하여 전고체형 수퍼커패시터를 제조하여 전기화학적 특성을 비교 하여 보았으며, 수퍼커패시터의 전기화학적 특성 역시 이온성 액체를 첨가하여 제조된 고체 전해질을 사 용하였을 때 향상된 전기화학적 특성을 나타내었다.

본 연구에서는 탄소나노튜브/화이버/폴리머 복합소재 구조에 대한 재료 물성 및 강성 추정을 다룬다. 수정된 Halpin-Tsai 모델을 적용한 멀티 스케일 해석은 탄소나노튜브의 함유량 비율, CNT 두께-길이 비율, 화이버 부피 함유량, 그리고 화이버 보강각도 변화에 따라서 수행되었다. 본 연구에서 제시한 멀티-스케일 접근방법은 기존 모델을 적용하여 얻은 결과와 비교하여 검증하였다. 매개변수 해석을 통하여 CNT의 적절한 함유량은 적층된 CNTFPC 구조의 구조성능의 향상시킬 수 있는 중요한 특성을 규명하였다.

본 연구에서는 polyvinylidene fluoride (PVDF) 중공사막을 지지체로 한 저압용 나노복합막을 제조하였다. Poly styrene sulfonic acid (PSSA)와 polyethyleneimine (PEI)을 layer-by-layer 및 염석 효과 방식으로 지지체막에 코팅하였다. 막의 투과도와 염 배제율 성능을 알아보고자 NaCl, MgCl2, CaSO4 100 mg/L수용액을 1 L/min의 유량으로, 2 bar의 압력을 상온에서 가해주었다. 20,000 ppm의 PSSA (이온세기 1.0)용액에 3분, 30,000 ppm (이온세기 0.1)용액에 1분 코팅한 막이 가장 우수하였다. 투과도와 염 배제율은 NaCl 공급액에서는 38.5 LMH, 57.1%, MgCl2는 37.9 LMH, 90.2%, CaSO4는 32.4 LMH, 54.6%로 각각 측정되었다.

Recent developments in the field of energy harvesting technology that convert ambient energy resources into electricity enable the use of self-powered energy systems in wearable and portable electronic devices without the need for additional external power sources. In particular, piezoelectric-effect-based flexible energy harvesters have drawn much attention because they can guarantee power generation from ubiquitous mechanical and vibrational movements. In response to demand for sustainable, permanent, and remote use of real-life personal electronics, many research groups have investigated flexible piezoelectric energy harvesters (f-PEHs) that employ nanoscaled piezoelectric materials such as nanowires, nanoparticles, nanofibers, and nanotubes. In those attempts, they have proven the feasibility of energy harvesting from tiny periodic mechanical deformations and energy utilization of f-PEH in commercial electronic devices. This review paper provides a brief overview of f-PEH devices based on piezoelectric nanomaterials and summarizes the development history, output performance, and applications.

Colloidally synthesized luminescent nanocrystals (NCs) have attracted tremendous attention due to their unique nanoscale optical and electronic properties. The emission properties of these NCs can be precisely tuned by controlling their size, shape, and composition as well as by introducing appropriate dopant impurities. Nowadays, these NCs are actively utilized for various applications such as optoelectronic devices including light emitting diodes (LEDs), lasers, and solar cells, and bio-medical applications such as imaging agents and bio-sensors. In this review, we classify luminescent nanomaterials into quantum dots (QDs), upconversion nanoparticles (UCNPs), and perovskite NCs and present their intrinsic emission mechanism. Furthermore, the recently emerging issues of efficiency, toxicity, and durability in these materials are discussed for better understanding of industry demands. As well, the future outlook will be offered for researchers to guide the direction of future research.

We carried out a dynamic instability assessment of carbon nanotube reinforced composite (CNTRC) and carbon nanotubes/fiber/polymer composite (CNTFPC) skew plates based on the high-order shear deformation plate theory (HSDT). The multiscale interactions between carbon nanotube (CNT) ratios and skew angles on the dynamic instability for various length-thickness ratios are studied using a two-dimensional finite element model developed for this study. The results were verified by those reported in the literature show the interactions between the CNT reinforcement and skew angles in the skew laminate. Numerical examples show the importance of CNT reinforcement when assessing the dynamic instability of CNTRC and CNTFPC skew plates.

Owing to high energy efficiency and superior efficacy, membrane-based desalination processes have gained widespread implementation in a wide variety of water treatment applications. Tremendous research efforts on new membrane materials have been made to improve the separation performance of the state-of-the-art thin-film composite (TFC) membranes, particularly polyamide TFC membranes, hoping to overcome the permeability-selectivity trade-off relations. Currently, many nanomaterials such as zeolites, metal-organic frameworks (MOFs), graphene oxide (GO), and carbon nanotubes (CNTs) have been explored to enhance the separation performance of existing polymeric membranes, but it has been argued that the positive transformation of nanomaterials-embedded TFC membranes hold promising potential to realize the sustainable development of current desalination membranes. Here we have tried to discuss some misconceptions and challenging items delaying industrial-scale implementation of nanomaterialsembedded desalination membranes.

In olefin/paraffin separation process, new technology such as membrane separation process has been ever demanding for both economic and environmental reasons. facilitated olefin transport membrane, containing positively charged silver nanoparticles (Ag NPs) by electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) as olefin carriers dispersed in poly(vinyl pyrrolidone) (PVP), shows extremely high separation performance for propylene/propane mixtures. However, higher permeance is always demanding for practical applications. In this study, POSSs were added to PVP/Ag NPs/TCNQ membranes. Among various kinds of POSS, trisilanolisooctyl POSS showed higher permeance with a moderate selectivity. Therefore it is concluded that mesoporous POSS is an effective additive in improving the gas permeance.