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Development of high durability plasma filter for air circulating disinfection system
Park Joo Young,Baek Ki Ho,Kim Sang-jin,Choi Joon-Hwan,Yoon Hyunkyung,Park Hunkwan,Kim Giyeong,이승훈 한국물리학회 2022 Current Applied Physics Vol.41 No.-
Deadly diseases are caused by pathogenic bacteria and viruses that spread, among other means, through air circulating systems; hence, it is important to focus on pathogen removal from the air before circulating air through the system. Our paper introduces a novel plasma-based filter that, when used in an air circulating system with particulate air filter, disinfects the air flow. This device, based on dielectric filter discharge (DFD) structure with low pressure drops, indicates easy installation into existing air circulating system. Its performance was evaluated in accordance with the specifications of duct used in hospitals, with consistent O3 generation during 200 h showing high durability. Escherichia coli and Micrococcus luteus were used as the target airborne bacteria; the system exhibited a removal efficiency of approximately 99.99% on bacterial aerosols and continuous bactericidal action, demonstrating that the DFD system can be directly applied to existing air circulating systems.
진공 플라즈마 용사법을 통해 형성된 NiCoCrAlY 오버레이 코팅의 반복 산화 거동
유연우(Yeon Woo Yoo),남욱희(Uk Hee Nam),박훈관(Hunkwan Park),박영진(Youngjin Park),이성훈(Sunghun Lee),변응선(Eungsun Byon) 한국표면공학회 2019 한국표면공학회지 Vol.52 No.6
MCrAlY overaly coatings are used as oxidation barrier coatings to prevent degradation of the underlying substrate in high temperature and oxidizing environment of the hot section of gas turbines. Therefore, oxidation resistance in high temperature is important property of MCrAlY coatings. Also, coefficients of thermal expansion (CTE) of MCrAlY have middle value of that of Ni-based superalloys and oxides, which have the effect of preventing the delamination of the surface oxides. Cyclic oxidation test is one of the most useful methods for evaluating the high temperature durability of coatings used in gas turbines. In this study, NiCoCrAlY overlay coatings were formed on Inconel 792(IN 792) substrates by vacuum plasma spraying process. Vacuum plasma sprayed NiCoCrAlY coatings and IN 792 susbstrates were exposed to 1000℃ one-hour cyclic oxidation environment. NiCoCrAlY coatings showed lower weight gain in short-term oxidation. In long-term oxidation, IN 792 substrates showed higher weight loss due to delamination of surface oxide but NiCoCrAlY coatings showed lower weight loss. X-ray diffraction (XRD) analysis showed α-Al2O3 and NiCr₂O₄ was formed during the cyclic oxidation test. Through cross-section observation using scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD) analysis, thermally grown oxide (TGO) layer composed of α-Al₂O₃ and NiCr₂O₄ was formed and the thickness of TGO increased during 1000℃ cyclic oxidation test. β phase in upper side of NiCoCrAlY coating was depleted due to oxidation of Al and outer beta depletion zone thickness also increased as the cyclic oxidation time increased.
( Sang-jin Kim ),( Seunghun Lee ),( Taeyoon Kim ),( Yoohyun Hwang ),( Hunkwan Park ),( Jun-yeong Yang ),( Joo Young Park ),( Kyoung-hoon Choi ),( Sungweon Ryoo ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.-
Background Until now, zone-sterilization was an advanced, mandatory, and expensive technique that was enforced at specialized cleanrooms that need regular sterilization, such as quality control evaluation centers (GMP), pharmaceutical product manufacturing plants, Biosafety Level 3 (BL3) laboratories, medical centers, and other various locations. One of the biggest problems in using large-surface chemical disinfectant at residential indoor locations is that there are many household items such as dishware, clothes, and bedding that may keep residual chemical sterilants, which may become dangerous to the respiratory system, skin, and even the eyes at exposure. Due to these reasons, after the initial disinfection using chemical disinfectant, a second cleaning step for the residual chemical sterilants is needed. Method This study developed a 60-liter chamber constructed to simulate the real-world environment in order to gauge a zonesterilizing device’s elimination capability. An aerosol generator aerosolized 2mL of pathogenic solution into the chamber for a given amount of time while the filtration module was on. Nine square petri dishes were attached to the inner surfaces of the chamber to collect surface-level pathogens, and an air-sampler with a gelatin filter was used to collect airborne pathogens. This study performed this experiment with both a commercial HEPA filter module and an air-passable plasma filter module, the latter which was developed for this study. Result This study developed the APF (Air-passable Plasma Filter) which is able to inactivate airborne pathogens and pathogens that can survive on indoor surfaces. We expect the '60-liter chamber' to become the most optimal and stable chamber model distributed commercially that can experiment with airborne pathogens. Conclusion The APF (Air Plasma Filter) and '60-liter chamber' developed for this study is expected to become the most stable and optimized commercialization chamber model that can experiment with airborne pathogens, and a next-generation air cleaning device.