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Roll-to-roll 공정으로 제조한 나노섬유가 코팅된 대면적 PTFE 필터 특성
안승환 ( Seunghwan Ahn ),이우진 ( Woo Jin Lee ),김연상 ( Yeonsang Kim ),심의진 ( Euijin Shim ),엄현진 ( Hyeonjin Eom ) 한국공업화학회 2022 공업화학 Vol.33 No.6
미세먼지 다량배출사업장의 미세먼지를 제거하는 백하우스의 백필터 여과체를 제작하기 위한 대면적 PTFE 나노섬유 제조 장치를 설계하여 제작하였다. 상용 PTFE 폼 필터의 미세먼지 여과효율을 높이기 위해 전기방사 공정과 열처리 공정을 이용하여 PTFE 나노섬유를 코팅하였다. PTFE 나노섬유를 대면적의 PTFE 폼 필터 표면에 연속적으로 코팅하기 위하여 roll-to-roll 공정용 장비와 제조 공정을 제안하였다. PTFE 나노섬유를 연속적으로 제작하기 위해 전기방사부와 열처리부를 roll-to-roll 공정에 맞게 장비를 최적화하여 설계하고 제작하였다. 본 장비를 이용하여 대면적 필터 여과체를 제조하고, 제조된 여과체의 표면 형태, 조성, 필터 특성을 확인하였다. 롤 형태의 대면적 여과체 전반에 걸쳐 PTFE 나노섬유가 균일하게 코팅되었고, 본 여과체는 280 °C에서도 280 °C에서도 PM2.5 기준 91.79%의 높은 집진효율과 1 m/min 기준 62 Pa의 우수한 압력 손실 특성을 보였다. The equipment for fabricating the large-area PTFE nanofiber coated-PTFE foam filter for use as filtration parts of the baghouse that removes particulate matter (PM) in industrial sites was designed and manufactured in this study. The PTFE nanofiber was coated on a commercial PTFE foam filter to increase its PM collection efficiency. The equipment and fabrication processes using a roll-to-roll system were proposed to continuously coat PTFE nanofibers on the surface of the PTFE foam filter. The electrospinning and annealing parts were designed and made by optimizing the equipment for the roll-to-roll system. The surface morphology, composition, and filtration characteristics of the large-area filter fabricated by this equipment were confirmed. PTFE nanofibers were uniformly coated on the large-area filter, and the PTFE nanofiber coated-PTFE foam filter showed PM2.5 collection efficiency of 91.79% and an appropriate pressure drop of 62 Pa with a face velocity of 1 m/min at 280 °C.
Effect of LED lighting on the cooling and heating loads in office buildings
Ahn, Byung-Lip,Jang, Cheol-Yong,Leigh, Seung-Bok,Yoo, Seunghwan,Jeong, Hakgeun Elsevier 2014 APPLIED ENERGY Vol.113 No.-
<P><B>Abstract</B></P> <P>LED lighting has the potential to provide energy savings, and in many countries, there are policies to encourage its use owing to its higher efficiency and longer life in comparison to other lighting fixtures. However, since 75–85% of the light electric power in LED lights is still generated as heat, the sole use of LED lighting in a building could have a negative effect on the cooling load. In this paper, we study the heating properties of LED lighting and establish a management strategy to exploit these properties to reduce the energy used for heating and cooling of buildings. Using a simulation program, the energy consumption of the Green Building in Daejeon, Korea, and the virtual building provided by the U.S. Department of Energy (DOE) was computed according for different light fixtures. A control strategy is more applicable to LED lighting than to general fluorescent lighting, especially for the cooling of a building, because the use of a return-air duct and the heat sinks on the LED fixtures allow the heat to be better directed. Deployment of LED lights in combination with such a control strategy can help to increase the energy efficiency of a building.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Application of heat control strategy reduces total energy consumption of LED lighting. </LI> <LI> Convective heat from LED lighting should be emitted outdoors during cooling period. </LI> <LI> Seasonal optimization of convective heat lowers total energy consumption. </LI> </UL> </P>
SSP based underwater CIR estimation with S-BiFPN
Seunghwan Seol,Jongmin Ahn,Hojun Lee,Yongcheol Kim,Jaehak Chung 한국통신학회 2022 ICT Express Vol.8 No.1
In underwater sensor networks (USN), channel impulse response (CIR) estimation based on sound speed profile (SSP) ensures link reliability. We propose a separate bi-directional feature pyramid network (S-BiFPN) that estimates the CIR using deep learning based on SSP. The proposed method enlarges the small variation of SSP by converting 1-dimension into 2-dimension, extracts various features using a fused feature map obtained from the separate paths, and estimates the CIR. Simulations are performed using the practically measured SSPs and CIRs, and the results show that the proposed method has the lowest mean square error (MSE) and a reasonable running time compared to conventional methods.
Choy, Seunghwan,Oh, Dongyeop X.,Lee, Seungwon,Lam, Do Van,You, Gihoon,Ahn, Jin-Soo,Lee, Seung-Woo,Jun, Sang-Ho,Lee, Seung-Mo,Hwang, Dong Soo American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.10
<P>Although biodegradable membranes are essential for effective bone repair, severe loss of mechanical stability because of rapid biodegradation, soft tissue invasion, and excessive immune response remain intrinsically problematic. Inspired by the exoskeleton-reinforcing strategy found in nature, we have produced a Ti-infiltrated chitin nanofibrous membrane. The membrane employs vapor-phase infiltration of metals, which often occurs during metal oxide atomic layer deposition (ALD) on organic substrates. This metal infiltration manifests anomalous mechanical improvement and stable integration with chitin without cytotoxicity and immunogenicity. The membrane exhibits both impressive toughness (∼13.3 MJ·m<SUP>-3</SUP>) and high tensile strength (∼55.6 MPa), properties that are often mutually exclusive. More importantly, the membrane demonstrates notably enhanced resistance to biodegradation, remaining intact over the course of 12 weeks. It exhibits excellent osteointegrative performance and suppresses the immune response to pathogen-associated molecular pattern molecules indicated by IL-1β, IL-6, and granulocyte-macrophage colony-stimulating factor expression. We believe the excellent chemico-biological properties achieved with ALD treatment can provide insight for synergistic utilization of the polymers and ALD in medical applications.</P> [FIG OMISSION]</BR>
Lee, Seunghwan,Lee, Sanghyeok,Kim, Hyo-Jin,Choi, Sung Min,An, Hyegsoon,Park, Mi Young,Shin, Jisu,Park, Jung Hoon,Ahn, Junsung,Kim, Donghwan,Ji, Ho-Il,Kim, Hyoungchul,Son, Ji-Won,Lee, Jong-Ho,Kim, Byun The Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.31
<P>Solid oxide fuel cell (SOFC) technology offers tremendous potential for highly efficient and clean power generation. However, its commercialization has lagged owing to the lack of long-term stability. Among the various sources of performance degradation, the interdiffusion between the cathode and electrolyte has been identified as a predominant factor. Herein, we demonstrate a highly reliable diffusion-blocking layer that completely suppresses detrimental chemical interactions at elevated temperatures. This diffusion-blocking layer is constructed <I>via</I> a bilayer approach, in which the top and bottom layers perform individual functions to precisely control the bulk and interfacial properties. Harnessing two types of specially designed nanoparticles for each part enables the realization of the desired film structure. Consequently, the formation of insulating phases and decomposition of the cathode are effectively prevented, resulting in a remarkable improvement in performance and stability. The scalability and feasibility of mass production are verified <I>via</I> the fabrication of large cells (10 cm × 10 cm) and a multi-cell stack. The stack in which the bilayer technique is implemented exhibits an extremely low degradation rate of 0.23% kh<SUP>−1</SUP>, which fulfills the strict lifetime requirement for market penetration. This work highlights a scalable, cost-effective, and reproducible method for the production of highly durable multilayer energy devices, including SOFCs.</P>