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황색산화철을 포함하는 혼합형 추진제의 특성에 관한 연구
박성준(Sungjun Park),원종웅(Jongung Won),박정호(Jungho Park),박의용(Euiyong Park),최성한(Sunghan Choi) 한국추진공학회 2018 한국추진공학회지 Vol.22 No.3
There is no significant difference in the initial viscosity of a propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material with added yellow iron oxide is faster than that with the addition of red iron oxide. Specifically, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure with yellow iron oxide than with red iron oxide. The initial viscosity was lowest at 71% of the large particle to small particle ratio.
황색산화철을 포함하는 혼합형 추진제의 특성에 관한 연구
박성준(Sungjun Park),최성한(Sunghan Choi),원종웅(Jongung Won),박정호(Jungho Park),박의용(Euiyong Park) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.5
황색 산화철과 적색 산화철을 적용한 추진제의 초기점도는 특이한 차이점이 없다. 또한 황색 산화철을 첨가한 물질의 열분해 속도가 적색 산화철을 첨가한 것 보다 빠르게 진행되며, 특히 고온 고압에서의 압력지수가 18% 낮은 것을 확인하였다. 황색 산화철을 적용한 추진제의 산화제 비율 변화에 따른 점도를 비교하면 큰 입자/작은 입자 비율 71%일 때 초기점도가 가장 낮았다. There is no unusual difference in the initial viscosity of the propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material added with yellow iron oxide is faster than that of the addition of red iron oxide. Especially, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure. The initial viscosity was lowest at 71% of large particle/small particle ratio.
Antiviral Properties of Silver Nanoparticles on a Magnetic Hybrid Colloid
Park, SungJun,Park, Hye Hun,Kim, Sung Yeon,Kim, Su Jung,Woo, Kyoungja,Ko, GwangPyo American Society for Microbiology 2014 Applied and environmental microbiology Vol.80 No.8
<P>Silver nanoparticles (AgNPs) are considered to be a potentially useful tool for controlling various pathogens. However, there are concerns about the release of AgNPs into environmental media, as they may generate adverse human health and ecological effects. In this study, we developed and evaluated a novel micrometer-sized magnetic hybrid colloid (MHC) decorated with variously sized AgNPs (AgNP-MHCs). After being applied for disinfection, these particles can be easily recovered from environmental media using their magnetic properties and remain effective for inactivating viral pathogens. We evaluated the efficacy of AgNP-MHCs for inactivating bacteriophage ϕX174, murine norovirus (MNV), and adenovirus serotype 2 (AdV2). These target viruses were exposed to AgNP-MHCs for 1, 3, and 6 h at 25°C and then analyzed by plaque assay and real-time TaqMan PCR. The AgNP-MHCs were exposed to a wide range of pH levels and to tap and surface water to assess their antiviral effects under different environmental conditions. Among the three types of AgNP-MHCs tested, Ag30-MHCs displayed the highest efficacy for inactivating the viruses. The ϕX174 and MNV were reduced by more than 2 log<SUB>10</SUB> after exposure to 4.6 × 10<SUP>9</SUP> Ag30-MHCs/ml for 1 h. These results indicated that the AgNP-MHCs could be used to inactivate viral pathogens with minimum chance of potential release into environment.</P>
Park, SungJun,Park, Hye Hun,Ko, Young-Seon,Lee, Su Jin,Le, The Son,Woo, Kyoungja,Ko, GwangPyo Elsevier 2017 Science of the Total Environment Vol.609 No.-
<P><B>Abstract</B></P> <P>Silver nanoparticles (AgNPs) have long been considered a powerful disinfectant for controlling pathogenic microorganisms. However, AgNPs might have adverse effects on both human health and our ecosystems due to their potential cytotoxicity and the difficulty in recovering them after their release into the environment. In this study, we characterized the antimicrobial efficacy caused by a novel micrometer-sized magnetic hybrid colloid (MHC) containing 7, 15, or 30nm sized monodispersed AgNPs (AgNP-MHCs), which can be re-collected from the environment using simple procedures, such as a magnet or centrifugation. We evaluated the antibacterial capabilities of AgNP-MHCs against target bacteria (<I>Legionella pneumophila, Bacillus subtilis</I>, <I>Escherichia coli</I>, and <I>Clostridium perfringens</I>) and compared them with the inactivation efficacy of AgNPs ~30nm in diameter (nAg30s). Among the different AgNP-MHCs composites evaluated, Ag30-MHCs had the greatest antibacterial effect. After 1h of exposure, more than a 4-log<SUB>10</SUB> reduction of <I>L. pneumophila</I> and 6-log<SUB>10</SUB> reduction of <I>B. subtilis</I> was achieved by 4.6×10<SUP>9</SUP> particles/mL of Ag30-MHCs and Ag30-MHC-Ls. In addition, Ag30-MHC-Ls maintained their strong antibacterial capabilities under anaerobic conditions. Our results indicate that AgNP-MHCs can be considered excellent tools for controlling waterborne bacterial pathogens, with a minimal risk of release into the environment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of AgNPs for controlling pathogens is hindered by several major obstacles. </LI> <LI> AgNP-MHCs can prevent the aggregation of AgNPs and be re-collected easily after use. </LI> <LI> AgNP-MHCs showed great antibacterial capabilities in various environmental conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Park Kwangmuk,Bang Junho,Bang Sunbae,Park Jinyoung,Hong Sungjun 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6
An ignition experiment was conducted with a cross-linked polyethylene insulated tray fl ame-retardant polyvinyl chloride sheathed cable by generating a 100 W direct current arc. The experiments generated a series arc by applying the UL 1699B revised standard and measuring arcing current, arcing voltage, etc. The reliability analysis was conducted using a statistical program on arc duration time and energy obtained through the measured data. The confi dence level of the probability distribution diagram and cumulative density function was within 95%, and the time and arc energy corresponding to 5% ignition probability was 2.38 s and 255 J, respectively. As for the 6% ignition probability, the ignition time was 2.64 s, exceeding the 2.5 s UL 1699B conformity standard. The time and arc energy corresponding to 50% ignition probability was 9.38 s and 697 J, respectively, indicating that the ignition probability within 10 s and 700 J was more than 50%. This study concluded that the conformity standard time in UL 1699B needs to be lower than 2.5 s for 100 W-level direct current arc generation tests based on the analysis results.