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Acute toxicity assessment for TiO₂ photocatalyst (GST) made from wastewater using TiCl₄ in rat
Ja Kyung Seol,Myeongkyu Park,Jae Min Im,Heung Sik Seo,Hee Ju Park,Sung Soon Nah 환경독성보건학회 2021 환경독성보건학회지 Vol.36 No.3
TiO₂ was a photocatalyst that used to the most common product because of the high efficiency. TiO₂ (P-25, commercial nanomaterial product) is the most typical photocatalyst product and TiO₂ (GST) was a sludge recycling product. This study was reported to evaluate an acute toxicity of TiO₂ (P-25 and GST) according to OECD test guideline 402 and 423 in Sprague-Dawley (SD) female rats via route of oral and dermal. There was investigated the lethal dose (LD<SUB>50</SUB>), and mortality, clinical signs, body weight changes and gross findings were continually monitored for 14 days following the single administration. After administration, TiO₂ (P-25) was calculated that LD<SUB>50</SUB> was considered to be a dose of over 2000 mg/kg body weight for both different route of exposure, and TiO₂ (GST) was the same. Other items were no observed an adverse effect between P-25 and GST; no mortality and clinical signs, accidental body weight loss, no gross findings. On the basis of the above results, the toxicity of the GST was almost equal to that of the commercial product, P-25 and there was no toxicological evidence.
FMEA 기법을 이용한 포술 훈련기의 잠재적 고장유형 분석 및 대책
이재원,이계경,나인성,박명규 明知大學校 産業技術硏究所 2008 産業技術硏究所論文集 Vol.27 No.-
This paper proposed design improvements and preventive measures for potential failure in order to assure of system reliability and support design of turret gunnery trainer. Relex program, which is automated FMEA technique, is used for FMEA analysis.
Fabrication of Invisible Ag Nanowire Electrode Patterns Based on Laser-Induced Rayleigh Instability
Oh, Harim,Lee, Jeeyoung,Kim, Jin-Hoon,Park, Jin-Woo,Lee, Myeongkyu American Chemical Society 2016 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.120 No.36
<P>We here present a laser-patterning method that may solve the-visibility problem associated with silver nanowire (AgNW) transparent electrodes. In conventional methods, AgNW electrodes are patterned on a transparent substrate by either selective removal or deposition of the material. Therefore, the fabricated pattern becomes visible due to the difference in transmittance/reflectance between the regions with and without AgNWs. Our approach is to disconnect the AgNW networks in selective areas by a laser and thus make the irradiated areas electrically insulating. This method is fundamentally based on Rayleigh instability. Given that the laser-cut nanowires remain on the substrate, the electrode pattern fabricated by the method can be invisible. The feasibility of the presented approach is demonstrated by fabricating organic light-emitting diodes using patterned AgNW electrodes and then characterizing their performance capabilities.</P>
소형 2행정 엔진의 전송 포트 형상에 따른 소기 성능에 대한 수치 해석적 연구
김청환(Cheonghwan Kim),박성호(Sungho Park),김명규(Myeongkyu Kim),안은수(Eunsoo Ahn) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.7
본 연구에서는 무인 항공기용 소형 2행정 엔진의 성능 개선을 위해 다양한 전송 포트 형상의 가스 교환 성능을 평가하였다. 성능 평가를 위해 네 가지 전송 포트 형상에 따른 3차원 전산 유체 해석을 진행하였으며, 가스 교환 성능의 정량적 평가를 위해 이상적 소기 모델인 완전 대체 소기 모델과 완전 혼합 소기 모델을 바탕으로 새로운 3단계 소기 모델을 개발하여 해석 결과에 적용하였다. 2행정 엔진의 전송 포트 형상 변경을 통해 흡기의 단락 현상을 효과적으로 줄였으며 가스 교환 과정 동안의 실린더 내 난류 에너지 또한 크게 개선되었다. 또한, 전송 포트 형상 별 3단계 소기 모델의 적용을 통해 가스 교환 성능을 정량적으로 평가할 수 있었으며, 포트 형상 별 소기 양상의 차이를 확인할 수 있었다. In this paper, the scavenging process of various transfer ports was evaluated to improve the performance of a small two-stroke engine for unmanned aerial vehicles. Three-dimensional computational fluid dynamics simulations were performed to four transfer ports for the evaluation, and a three-phase scavenging model was developed and applied to the simulation results for the quantitative comparison of scavenging performance. the short-circuit of fresh charge was restrained and an in-cylinder turbulent kinetic energy was enhanced by changing the transfer port. Also, a difference in the scavenging for each port were confirmed by applying the three-phase model to the simulation results.
방켈 로터리 엔진의 포트 형상 및 로터 리세스 슬롯 유무에 따른 엔진 내 유동에 대한 수치 해석적 연구
김청환(Cheonghwan Kim),박성호(Sungho Park),김명규(Myeongkyu Kim),고준만(Junman Ko),김정우(Jeongwoo Kim),안은수(Eunsoo Ahn) 한국추진공학회 2022 한국추진공학회 학술대회논문집 Vol.2022 No.5
방켈 로터리 엔진은 하우징 내부의 로터가 편심축을 중심으로 회전하면서 작동하는 내연 기관의 한 형태이다. 방켈 로터리 엔진은 배기량 대비 출력이 높다는 특성 때문에 기관 중량 대비 높은 비출력의 확보가 필요한 무인 항공기의 추진 장치로 적합한 것으로 평가받고 있다. 그러나 납작한 형태의 연소실 형상으로 인해 화염의 소멸이 발생하는 면적이 넓고 불완전한 연소가 쉽게 발생해 연소 효율이 낮은 실정이다. 이러한 문제를 해결하거나 최소화한다면 방켈 로터리 엔진 성능의 큰 개선을 이룰 수 있을 것이다. 본 연구에서는 3차원 전산 유체 해석을 통해 방켈 로터리 엔진의 흡기 포트 단면 형상 및 로터 리세스 슬롯 유무에 따른 연소실 내 유동 변화를 확인하였다. 연소실 내 일부 지점에서 난류 강도를 취득하고 포트 유량을 비교하여 방켈 로터리 엔진의 설계 변화에 따른 유동 변화를 확인하였다. Wankel rotary engine is one of the Internal Combustion Engines worked by rotating a eccentric rotor inside an engine housing. Wankel rotary engine is considered as a suitable propulsion device for unmanned aerial vehicles because it provides high power-to-weight and power-to-volume ratio. However its long and narrow combustion chamber induces and larger quenching zones and incomplete combustion, which result in poor combustion efficiency. Resolving or minimizing these problems could lead to improvements in Wankel rotary engine performance. In this paper, flow characteristics such as turbulent kinetic energy and mass flow rate through the intake port by cross-section design of the intake port and the presence of a rotor recess slot was evaluated by three-dimensional computational fluid dynamics.
소형 2행정 엔진의 전송 포트 형상에 따른 소기 성능에 대한 수치 해석적 연구
김청환(Cheonghwan Kim),박성호(Sungho Park),김명규(Myeongkyu Kim),안은수(Eunsoo Ahn) 한국추진공학회 2020 한국추진공학회지 Vol.24 No.6
In this paper, the scavenging process of various transfer ports was evaluated to improve the performance of a small two-stroke engine for unmanned aerial vehicles. Three-dimensional computational fluid dynamics simulations were performed to four transfer ports for the evaluation, and a three-phase scavenging model was developed and applied to the simulation results for the quantitative comparison of scavenging performance. the short-circuit of fresh charge was restrained and an in-cylinder turbulent kinetic energy was enhanced by changing the transfer port. Also, a difference in the scavenging for each port were confirmed by applying the three-phase model to the simulation results.