• 생명과학회지
• /
• 제28권7호
• /
• pp.864-873
• /
• 2018

나노 입자는 화장품, 식품, 기계, 화학 산업 등에 다양한 용도로 활용되고 있으며, 그 응용분야가 광범히 하여 나노 입자 사용에 대한 관심과 연구가 지속적으로 증가하고 있는 추세이다. 특히 금속나노 입자 중 하나인 은나노 입자는 항균 및 항진균 효과가 뛰어나 의류, 실내 공기필터, 증류필터 등 다양한 방면에 활용되고 있다. 하지만 은나노 입자의 지속적인 노출 시, 입자 크기와 노출방식에 따라 인체에 독성을 유발하는 것으로 알려져 있어 친환경적이고 생물학적으로 안전한 천연물 유래 소재를 활용한 은나노 입자의 기술개발이 필요하다. 천연물이 적용된 실내필터와 의류는 생산의 용이성, 제품 내구성 및 항균 활성에서 은나노 적용제품과 비교될 수 있는 것으로 나타고 있다. 본 연구에서는 은나노의 생체 내 미치는 독성 메커니즘에 대해 알아보고 은나노의 대안으로 항균 활성을 지닌 천연물의 항균 활성에 대해 기술하고자 한다.

• Environmental Analysis Health and Toxicology
• /
• 제21권1호
• /
• pp.45-56
• /
• 2006

This study was conducted to investigate seasonal distributions of fine particles ($PM_{2.5}$) and associated polycyclic aromatic hydrocarbons (PAHs) at three cities. $PM_{2.5}$ samples were collected on glass fiber filters at urban (Chuncheon), metropolitan (Seoul), and industrial complex sites (Ulsan) from September, 2002 to February, 2004 using the Andersen FH 95 Particulate Sampler. About five 24-hour samples were collected from each site per season. The filters were analyzed for mass and six selected PAHs concentrations. $PM_{2.5}$ concentrations were the highest either in winter or spring, which could be attributed to the increase of fossil fuel combustion in winter or the transport of yellow sand to the Korean peninsula from China in spring, respectively. Regional $PM_{2.5}$ concentrations were higher in the order of Seoul>Chuncheon>Ulsan without statistical difference among cities. The filters were extracted using dichloromethane in an ultrasonicator and analyzed for six PAHs (anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, and benzo[a]pyrene) with HPLC. Total PAHs concentrations were statistically different among seasons in each site, and the highest concentrations were observed in winter at each sampling site. For total samples collected, the median total PAHs concentrations in Chuncheon ($4.6ng/m^3$) and Seoul ($4.4ng/m^3$) were approximately two times higher than that in Ulsan ($2.1ng/m^3$). Chrysene was a component found in the highest proportion among total PAHs at each site. Carcinogenic risks calculated based on the BaP toxic equivalency factors (TEFs) over the whole sampling period were higher in the order of Chuncheon>Seoul>Ulsan. This study suggests that the atmosphere of Chuncheon is contaminated with particulate matter and PAHs at the levels equivalent to those of Seoul and that an appropriate measure needs to be taken to mitigate human health risks from inhalation exposure to airborne fine particles.

• 한국입자에어로졸학회지
• /
• 제12권3호
• /
• pp.95-102
• /
• 2016

본 연구에서는 호흡용 보호구 필터의 나노물질에 대한 여과특성을 측정하기 위해서 소금(NaCl)과 은나노입자(Ag)를 대상으로 입경별 집진효율을 평가하였다. 호흡용 보호구 필터는 특급 방진마스크와 1급 방진마스크의 두 가지 안면부 여과식 방진마스크인 사용하였고, 마스크의 배기밸브 부분을 제외한 필터 여재 부분을 직경 47 mm로 잘라내어 필터홀더에 부착하여 입경별 입자제거효율을 시험하였다. 시험입자는 일반적으로 시험 입자로 사용되는 소금입자는 분무형 입자발생장치를 사용하여 발생하였고 중화기를 통과시켜 입자의 하전특성을 볼츠만 분포로 만들어 공급하였다. 은나노입자의 경우, 기화-응축 방법을 이용한 금속나노입자 생성방법인 ISO10801 방법을 사용하였다. 작업장의 은나노입자의 고농도 노출을 모사하기 위해, 중화기를 통과하지 않은 나노입자를 시험입자로 사용하였다. 은나노입자의 경우 소금입자로 만들기 어려운 20nm 이하의 입자를 안정적으로 효과적으로 만들어 시험에 적용하였고, 나노 크기에서도 매우 안정적인 데이터를 확보할 수 있었다. 1급 마스크 필터와 특급 마스크 필터에 대한 소금입자의 평가에서, 입경별 최소효율이 30~50nm 사이에서 나타나는 특성은 기존 연구와 비슷한 결과를 얻었다. 반면, 은나노입자의 경우 1급 마스크 필터와 특급 마스크 필터 모두에서 비슷한 크기의 소금 입자와 비교할 때 높은 효율을 나타냈다. 이것은 소금 입자의 경우 중화기를 통과시켜 시험입자로 사 용한 반면, 은나노입자의 경우 중화기를 통과시키지 않았기 때문이다. 본 연구에서는 작업장에서 은나노 입자가 고농도로 노출될 경우를 모사하여, 기화-응축에 의한 방법의 은나노입자 발생장치를 사용하였는데, 이 때 상대적으로 높게 대전된 입자들이 많이 만들어진다(Jung et al., 2006). 이로 인해, 정전필터인 마스크 필터의 포집 효과가 상대적으로 크기 때문에, 입경별 효율이 높아진 것으로 생각된다. 본 연구에서 평가한 1급 및 특급 방진마스크 여재의 최소 포집효율은 유럽 EN 149 기준인 95 LPM 유량 기준을 만족하는 것으로 나타났지만, 이것은 여재에 대한 평가 결과로, 실제 마스크에 대해서는 여재의 구조적인 불균일성이나 마스크를 착용하는 과정에서 밀착이 되지 않아 누출될 가능성은 마스크 사용에 고려되어야 한다. 불시에 발생할 수 있는 작업장 내 안전사고의 예방을 위하여 적절한 보호구의 선택과 올바른 착용 및 유지관리가 필요할 것으로 생각된다.

• 한국산업보건학회지
• /
• 제5권2호
• /
• pp.172-183
• /
• 1995

The airborne concentrations of the welding fumes produced during $CO_2$ arcwelding process at shipbuilding, shiprepairing, container manufacturing and car accessary manufacturing industry were investigated. The effects how much reduced the welding fume were checked when the portable fan was used. The results were as follows; 1.The geometric mean of welding fume concentration in shipbuilding factory was $10.05mg/m^3$. This exposure concentration was higher than other 3 manufacturing industries at 95% confidence level. 2. The sampling filters for welding fume could be digested with acid within 1 hour by microwave oven. The recoveries for investigated metal elements were all over 95%. 3. The optimal wavelength could be selected for the simultaneous analysis of 8 metal elements by ICP(Inductively Coupled Plasma). 4. Noxious gases($O_1,NO_2$) produced during $CO_1$ gas arc welding process were detected that the concentration of ozone($O_1$) was less than 0.01 ppm and that of nitrogen dioxide($NO_2$) was 0.01-0.03 ppm. 5. The geometric mean of welding fume particle diameter was $1.26{\mu}m$ and geometric standard deviation was 1.51 for the counts when particle an analyzer(ELZONE) had been used. 6. When the portable fan had been used,the reduced percent of total welding fume for workers was about 47.8% when portable fan was applied to blow and 71.7% when to exhaust.

• 한국재료학회지
• /
• 제14권7호
• /
• pp.470-476
• /
• 2004

The fail safety filter is an assistant filter element to be mounted in order to intercept the particles leaked when the main filter elements are broken. So it should have two contrary functions of being plugged easily to meet the purpose of dust sealing and a high permeability to save the space. The permeability of the metal filter elements were effectively controlled by the following factor: powder size(53-840 ${\mu}m$) and applied pressure(1000-2000 $kgf/cm^2$), and then the compact were sintered for 1 hour at $1200^{\circ}C$ in vacuum sintering furnace. The sintered metal filters was evaluated for the function of the fail safety filter in an experimental unit. The maximum allowable particle size was 420-840 ${\mu}m$, when a CIP pressure of 1500 $kgf/cm^2$ was applied reveals a permeability of about $1.2{\times}10^{10}m^2$ and pore size of about 60 ${\mu}m$. The metal filter produced with stainless steel powder of 480-840 ${\mu}m$ size, which presented excellent permeability than commercial ceramic filter element and plugged with in 3 minutes with the leak of the maximum particle size less than 3 ${\mu}m$.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.901-905
• /
• 2005

Monte Carlo localization is known to be one of the most reliable methods for pose estimation of a mobile robot. Much research has been done to improve performance of MCL so far. Although MCL is capable of estimating the robot pose even for a completely unknown initial pose in the known environment, it takes considerable time to give an initial estimate because the number of random samples is usually very large especially for a large-scale environment. For practical implementation of the MCL, therefore, a reduction in sample size is desirable. This paper presents a novel approach to reducing the number of samples used in the particle filter for efficient implementation of MCL. To this end, the topological information generated off- line using a thinning method, which is commonly used in image processing, is employed. The topological map is first created from the given grid map for the environment. The robot scans the local environment using a laser rangefinder and generates a local topological map. The robot then navigates only on this local topological edge, which is likely to be the same as the one obtained off- line from the given grid map. Random samples are drawn near the off-line topological edge instead of being taken with uniform distribution, since the robot traverses along the edge. In this way, the sample size required for MCL can be drastically reduced, thus leading to reduced initial operation time. Experimental results using the proposed method show that the number of samples can be reduced considerably, and the time required for robot pose estimation can also be substantially decreased.

• 대한기계학회논문집B
• /
• 제25권11호
• /
• pp.1650-1658
• /
• 2001

An electret filter is composed of permanently charged electret fibers and is widely used in applications requiring high collection efficiency and low-pressure drop. In this work, the fractional collection efficiency of the filter media used in manufacturing cabin air filters was investigated by using highly monodisperse particles ranging from 0.02 to 0.6 $\mu\textrm{m}$ in diameter at three different charging states: singly charged, uncharged, and equilibrium charged. The face velocity was varied from 2.4 to 20.4 crus. It was fecund that the fractional efficiency curve fur singly charged particles shows a typical trend that the collection efficiency is minimum at about 0.3 $\mu\textrm{m}$ in diameter. The fractional efficiency of equilibrium charged particles were not severely varied with the particle diameter. The collection efficiency curve fur uncharged particles has a minimum near 0.1 $\mu\textrm{m}$ in diameter. Another experiment was conducted for a cartridge filter to examine the effect of charge depletion on the collection efficiency in a cabin air filter. The result shows that the charge depletion of the cartridge filter can significantly lower the collection efficiency.

• 한국정보통신학회논문지
• /
• 제22권6호
• /
• pp.849-854
• /
• 2018

넓은 지역에 광범위하게 분포되어 있는 통신용 무선기지국은 관리에 많은 어려움이 있다. 특히 산간 오지에 있는 무인 통신무선 기지국은 위급한 상황 발생시에 접근에 많은 어려움을 겪고 있다. 대형 통신회사들은 송수신 정보만 원격으로 관리하고 있고 실제 시설 유지를 책임지고 있는 지역 중소기업 협력업체들은 이러한 기술을 보유하고 있지 않아서 일일이 현장 방문을 통하여 확인하고 있는 실정이다. 본 연구에서는 넓은 범위에 산재해 있는 무선기지국내의 온도, 습도, 화염 발생여부, 전원 동작 여부를 실시간으로 모니터링 하여 클라우드 서버에 보내 사무실에서 실시간 모니터링을 통하여 관리하며 위급시 경고 메시지 전송 등이 수행이 가능한 시스템을 클라우드 서버 구축을 통하여 IoT 센서 기술을 이용하여 구현한 내용을 제시하고자 한다.

• 한국대기환경학회지
• /
• 제11권1호
• /
• pp.37-44
• /
• 1995

Concentration of particulate nitrate classified by formation mechanism and particle diameter in ambient air was determined from Feb. to Oct. 1993. Sampling was carried out using a two-stage Andersen air sampler at the top of a five-story building located at Kon-Kuk University in seoul. Concentration of N $H_{4}$N $O_{3}$ in TSP was measured by pyrolysis of sample filters at 160.deg.C for 1hr. concentration of N $H_{4}$N $O_{3}$ was higher in winter time compared with that in summmer time. Also, concentration of N $H_{4}$N $O_{3}$ was higher in fine particles compared with that in coarse particle. The range of N $H_{4}$N $O_{3}$ concentration was between 2.9 and 9.9.mu.g/ $m^{3}$. Weight fraction of N $H_{4}$N $O_{3}$ in total particulate nitrate was 31.1 .sim. 59.5%, and weight fraction of N $H_{4}$N $O_{3}$ in TSP was 2.1 .sim. 11.2%. Concentration of NaN $O_{3}$, which originated from sea salt, was highest in spring time and lowest in summer time,and the concentration range was between 0.1 and 0.7.mu.g/ $m^{3}$. NaN $O_{3}$/TSP ratio was very low (0.1 .sim. 0.4%) indicating that the portion of NaN $O_{3}$in TSP was negligible. Concentration of particulate nitrate originated from soil was 2.4 .sim. 2.9.mu.g/ $m^{3}$. Weight fraction of that in total particulate nitrate was 14.0 .sim. 37.1%.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.281-281
• /
• 2010

Very low refractive index (<1.4) materials have been proved to be the key factor improving the performance of various optical components, such as reflectors, filters, photonic crystals, LEDs, and solar cell. Highly porous SiO2 are logically designed for ultralow refractive index materials because of the direct relation between porosity and index of refraction. Among them, ordered macroporous SiO2 is of potential material since their theoretically low refractive index ~1.10. However, in the conventional synthesis of ordered macroporous SiO2, the time required for the crystallization of organic nanoparticles, such as polystyrene (PS), from colloidal solution into well ordered template is typical long (several days for 1 cm substrate) due to the low interaction between particles and particle - substrate. In this study, polystyrene - polyacrylic acid (PS-AA) nanoparticles synthesized by miniemulsion polymerization method have hydrophilic polyacrylic acid tails on the surface of particles which increase the interaction between particle and with substrate giving rise to the formation of PS-AA film by simply spin - coating method. Less ordered with controlled thickness films of PS-AA on silicon wafer were successfully fabricated by changing the spinning speed or concentration of colloidal solution, as confirmed by FE-SEM. Based on these template films, a series of macroporous SiO2 films whose thicknesses varied from 300nm to ~1000nm were fabricated either by conventional sol - gel infiltration or gas phase deposition followed by thermal removal of organic template. Formations of SiO2 films consist of interconnected air balls with size ~100 nm were confirmed by FE-SEM and TEM. These highly porous SiO2 show very low refractive indices (<1.18) over a wide range of wavelength (from 200 to 1000nm) as shown by SE measurement. Refraction indices of SiO2 films at 633nm reported here are of ~1.10 which, to our best knowledge, are among the lowest values having been announced.