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전기유도로를 이용한 주철주조 용해공정에서 발생하는 분진의 형상 특성
박현설 ( Hyun-seol Park ),임경수 ( Kyoung-soo Lim ) 한국환경기술학회 2008 한국환경기술학회지 Vol.9 No.2
본 연구에서는 주철 주조 공정 중 전기로를 이용한 용해 공정에서 발생하는 분진의 형상 및 조성, 그리고 분진의 농도를 분석하였다. 용해공정에서 발생하는 분진은 각각의 작업 조건에 따라 독특한 형상과 조성을 보였는데, 고철에 포함된 유기물이 연소될 때는 그을음 분진이 발생하였으며, 구상흑연주철 제조시 출탕조건에서는 육면체의 결정구조를 갖는 마그네슘산화물 분진이 발생하였다. 출탕직전과 직후에 용해로에서 발생되는 분진은 아연산화물, 망간산화물, 철산화물 및 규소산화물 등으로 구성되었으며 황토색을 보였다. 분진농도측정기와 SEM 사진을 통해 확인한 바에 의하면 용해공정에서 발생하는 분진은 인체에 대한 위해성이 높은 PM<sub>2.5</sub>가 대부분이었으며 특히 출탕조건에서 발생하는 분진은 95% 정도가 PM<sub>2.5</sub>로 이루어졌음을 알 수 있었다. 본 연구의 결과는 향후 주조업체의 작업환경 개선을 위한 기초자료로 이용할 수 있을 것이다. In this work, the morphological property of dust particles emitted from melting process of iron foundries was investigated. The shape, chemical composition, and concentration of dust particles for each of melting processes of iron casting were also examined. Soot particle agglomerates were formed when organic impurities stuck to scrap iron were burning, while rectangular shape MgO particles were generated through the pouring process for ductile iron casting. Zinc oxides, manganese oxides, iron oxides, and silicon dioxide were significant components of dust particles emitted from furnace just before and right after pouring process. It was found that most of dust particles from iron melting process, especially over 95% for the pouring process, were PM<sub>2.5</sub>.
밀폐공간에서 비말 가림막 높이에 따른 감염성 비말 공기전파 차단능력 평가
허지은,조희주,박현설,신동호,심준목,조윤행,Heo, Jieun,Cho, Hee-joo,Park, Hyun-Seol,Shin, Dongho,Shim, Joonmok,Joe, Yun-Haeng 한국입자에어로졸학회 2021 Particle and Aerosol Research Vol.17 No.2
Although the installation of droplet protection screen (DPS) is known to prevent droplet transmission, there is still a lack of knowledge in effectiveness of DPS installation to block the airborne transmission. In this study, the prevention ability of DPS against airborne transmission was evaluated according to the DPS height. When the DPS was not installed, the maximum concentration of PM1.0 at the location opposite to infected person was 35% of that at the infected person location. When the DPS was installed, the DPS effectively prevented the airborne transmission, consequently approximately 7% of generated particles were measured at the opposite location from particle generation position (infected person location). The prevention ability of DPS increased with DPS height, the maximum prevention efficiency of 95.1% was obtained when the DPS height was 900mm. Moreover, the speed of airborne transmission was delayed by installation of DPS, and the delay time increased with DPS height.
조윤행,신동호,박현설,허지은,심준목,Joe, Yun-Haeng,Shin, Dongho,Park, Hyun-Seol,Heo, Jieun,Shim, Joonmok 한국입자에어로졸학회 2021 Particle and Aerosol Research Vol.17 No.2
In this study, the clean air delivery rate (CADR) of ceiling air circulator (CAA) was determined under indoor environmental simulation conditions. An air filter was used to provide air cleaning ability to the CAA. The CADR of filter adapted CAA was evaluated and compared with the value of commercial air purifier. The installation of mesh-shaped filter on the CAA showed particle reduction effect on the particles over 0.4 ㎛ in diameter, but the CADR was up to 0.25 m<sup>3</sup>/min. When the filter having 99.9% in collection efficiency was installed on the CAA, its CADR was 1.52 m<sup>3</sup>/min, while the CADR of commercial air purifier was 3.19 m<sup>3</sup>/min.
수분회수 냉각탑에 적용되는 중공사막 모듈의 유동특성에 관한 수치해석적 연구
박상철(Sang Cheol Park),박현설(Hyun Seol Park),이형근(Hyung Keun Lee),신원규(Weon Gyu Shin) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.8
본 연구의 목적은 수분회수 냉각탑에 설치된 엇갈림(staggered) 형태로 배치된 중공사막 모듈을 다공성 매질(porous medium)로 모델링 시 유동특성을 수치 해석적으로 검토하는 것이다. 1단으로 설치된 중공사막 모듈의 차압 데이터를 이용하여 다공성 매질의 모델링을 위한 압력-속도 2차 식을 도출하였다. 중공사막 모듈을 다공성 매질로 모델링한 경우 (“다공성 매질”)와 중공사막 모듈의 형상을 그대로 고려한 경우 (“멤브레인 모듈”)에 대해 유동 특성을 비교하였다. “다공성 매질”의 경우 “멤브레인 모듈”에 비해 유동에 의한 압력 변화는 0.6 % 미만의 적은 차이를 나타냈으나, 최대 유속은 약 2.5배, 평균 난류 운동에너지는 95배로 크게 나타났다. 이를 통해 다공성 매질로의 모델링은 압력강하는 잘 구현하나, 유속 및 난류 운동에너지는 잘 모사하지 못함을 알 수 있었다. The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the "porous medium" when the membrane module was modeled as a porous medium with the case of the "membrane module" when considering the original shape of the membrane module. The difference in pressure drop between the "porous medium" and "membrane module" was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the "porous medium" were 2.5 and 95 times larger than those of the "membrane module," respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.
Gerdien 이온측정기를 이용한 에어로졸의 하전 특성 분석에 관한 연구
조윤행,심준목,신일경,육세진,박현설,Joe, Yun-Haeng,Shim, Joonmok,Shin, Il-Kyoung,Yook, Se-Jin,Park, Hyun-Seol 한국입자에어로졸학회 2018 Particle and Aerosol Research Vol.14 No.1
Since the motion of the charged particle strongly depends on its charge characteristics, information on charge distributions of target particles is one of the important variables in aerosol research. In this study, charged distribution of atomized NaCl particles were measured using a Gerdien type ion counter. Two kinds of particle charging conditions were used in this study. First, atomized NaCl particles were passed through an aerosol neutralizer to have a Boltzmann charge distribution, and then its charge distribution was measured. In this case, the portion of uncharged particles was compared with the portion obtained from the Boltzmann charge distribution for verifying the suggested experimental method. Second, same experiment was conducted without the aerosol neutralizer to measure the charge distribution of atomized and un-neutralized NaCl particles. In the conclusion, the portion of uncharged, negatively charged and positively charged particles were 19%, 62% and 20%, respectively, for neutralized particles. The atomized particles, which was generated without the aerosol neutralizer, also had almost a zero charge state, but the standard deviation in charge distribution was larger than that of neutralized particles. The test method proposed in this study is expected to be used in various aerosol research fields because it can obtain simple information on the particle charge characteristics more easily and quickly than the existing test methods.