• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1505-1515
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• 2009

A new method to semicontinuously determine $PM_{2.5}$ ionic species with a short time resolution is described in detail. In this system, a particle collection section (mixing part, particle collection chamber, and air/liquid separator) was developed. A Y-type connector was used to mix steam and an air sample. The particle collection chamber was constructed in the form of a helix coil and was cooled by a water circulation system. Particle size growth occurred due to the high relative humidity and water absorbed particles were efficiently collected in it. Liquid samples were drained out with a short residence time (0.08-0.1 s). The air/liquid separator was also newly designed to operate efficiently when the flow rate of the air sample was 16.7 L $min^{-1}$. For better performance, the system was optimized for particle collection efficiency with various types of test aerosols such as ($NH_4)_2SO_4,\;NaCl,\;NH_4HSO_4,\;and\;NH_4NO_3$. The particle collection efficiencies were almost 100% at different concentration levels in the range over 500 nm in diameter but 50-90% in the range of 50-500 nm under the following experimental conditions: 15 coil turns, a water flow rate for steam generation of 0.65 mL $min^{-1}$, and an air sample flow rate of 16.7 L $min^{-1}$. Finally, for atmospheric applications, chemical compositions of $PM_{2.5}$ were determined with a time resolution of 20 min on January 11-24, 2006 in Seoul, Korea, and the chemical characteristics of $PM_{2.5}$ ions were investigated.

• 한국광학회지
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• 제26권1호
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• pp.9-16
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• 2015

얼음 구름과 에어로의 후방산란 특성을 측정할 수 있는 타원 편광라이다를 구성하고 이를 이용하여 에어로졸과 얼음 구름의 특성을 측정하였다. 규격화된 전체 후방산란 뮬러 행렬을 구하기 위하여 3 개의 광학계(${\lambda}/4$ 파장판, ${\lambda}/2$ 파장판, 그리고 빈 공간)로 구성된 조사 광학계와 같은 구조로 된 수신광학계를 통하여 총 9 개의 라이다 시스템을 구축하였다. 구축된 광학계의 체계적 오차를 구하기 위하여 에어로졸의 농도가 낮은 높은 고도의 9 개의 라이다 신호를 이용하였다. 9 개의 라이다 신호를 이용하여 5 개의 광학계 설치 오차(offset angle)와 무질서하게 배열된 에어로졸에 대한 뮬러 메트릭스 요소(2 개)를 찾아내었다. 광학장치를 검정한 후 얼음구름과 에어로졸에서 NBSPM (Normalized Backscattering Phase Matrix)를 구하였으며, 그 결과 에어로졸의 경우 입자의 방향성과 관계되는 NBSPM 의 비대각 행렬이 얼음 구름의 그것보다 작음을 알 수 있었다. 그리고 권운의 경우에도 NBSPM 의 비대각 행렬이 변하는 기상 조건에 따라 달라지는 것을 볼 수 있었다.

• 한국입자에어로졸학회지
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• 제10권4호
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• pp.137-154
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• 2014

문헌조사를 통해 그동안 선행연구로부터 밝혀진 방사성 에어로졸의 특성을 종합하고 정리하였다. 가상사고 실험 중 각재계통 및 원자로건물에서 측정한 에어로졸의 특성, 냉각재계통 및 원자로건물에서의 방사성 에어로졸 거동 해석을 위해 사용된 모델 에어로졸의 특성, 공학적 안전설비 성능평가를 위한 실험에 사용된 모델 에어로졸의 특성 등과 관련한 선행연구 내용을 종합해 볼 때, 원전사고 시 발생하는 에어로졸의 MMD는 $0.1{\sim}5{\mu}m$, GSD는 1.33~2.9, 에어로졸 농도는 $0.06{\sim}132g/m^3$의 범위를 보였다. 향후 공학적 안전설비의 설계를 위한 MMD와 GSD의 대표값은 대략 $1.5{\mu}m$와 1.8 내외라고 할 수 있으며, 에어로졸 농도는 대략 $10g/m^3$을 대표값으로 볼 수 있다.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.89-102
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• 2013

24-hr $PM_{2.5}$ samples were collected from January 19 through February 27, 2009 at an urban site of Gwangju and analyzed to determine the concentrations of organic and elemental carbon(OC and EC), water-soluble OC(WSOC), eight ionic species($Na^+$, $NH^{4+}$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), and 22 elemental species. Haze phenomena was observed during approximately 29%(10 times) of the whole sampling period(35 days), resulting in highly elevated concentrations of $PM_{2.5}$ and its chemical components. An Asian dust event was also observed, during which $PM_{2.5}$ concentration was 64.5 ${\mu}g/m^2$. Crustal materials during Asian dust event contributed 26.6% to the $PM_{2.5}$, while lowest contribution(5.1%) was from the haze events. OC/EC and WSOC/OC ratios were found to be higher during haze days than during other sampling days, reflecting an enhanced secondary organic aerosol production under the haze conditions. For an Asian dust event, enhanced concentrations of OC and secondary inorganic components were also found, suggesting the further atmospheric processing of precursor gases during transport of air mass to the sampling site. Correlations among WSOC, EC, ${NO_3}^-$, ${SO_4}^{2-}$, and primary and secondary OC fractions, which were predicted from EC tracer method, suggests that the observed WSOC could be formed from similar formation processes as those of secondary organic aerosol, ${NO_3}^-$ and ${SO_4}^{2-}$. Results from principal component analysis indicate also that the observed WSOC was strongly associated with formation routes of the secondary organic and inorganic aerosols.

• 한국환경과학회지
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• 제4권1호
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• pp.53-62
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• 1995

대기중의 산성도($H^+$)를 측정하기 위하여 디누더 시스템(Annula Denuder System)을 이용하였다. 산성도 측정은 1990년 4월 부터 1001년 3월 까지 미국 시카고에서 81개 샘플을 12시간 동안 낮과 밤을 구분하여 측정하였다. 본 연구를 통하여 대기중의 산성도 측정은 디누더 시스템을 이용하면 보다 정확한 결과를 얻을 수 있을음 알 수 있었다. 여과지에 포집된 산성도($H^+$)를 추출해 낼때 사용하는 $HCIO_4$용액은 $10^{-5}N$의 농도를 사용하는 것이 $10^{-4}N$의 농도보다 더 정확한 결과를 얻을 수 있다. 보다 정확한 산성도를 측정하기 위해서는 에어로졸이 여과지에 포집되기 전에 가스 상태의 $NH_3$가 먼저 제거되어야 한다. 산성도는 계절에 따라 변하였고 여름에 가장 높은 농도를 나타냈다. $SO_4^{2+} 와 $NH_4^+$, 그리고 $SO_4^{2+}와 $H^+$의 상관관계는 높은 것으로 나타났다.

• 대한원격탐사학회지
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• 제26권2호
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• pp.175-188
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• 2010

세계 최초로 정지 상태로 해색을 관측하는 정지궤도해색탑재체(GOCI, Geostationary Ocean Color Imager) 값의 보정을 위해서는 기존의 방법이 아닌 새로운 방법이 요구된다. 본 연구에서는 GOCI의 특별한 특성에 맞는 새로운 대기보정 방법과 양방향성 광반사 분포함수(BRDF, Bidirectional Reflectance Distribution Function) 보정 방법을 소개하고자 한다. GOCI의 대기보정을 위해서 스펙트럼 형태 조화기법(SSMM, Spectral Shape Matching Method)과 Sun Glint Correction Algorithm(SGCA)을 개발하였고, BRDF 보정을 위하여 해수의 고유광특성(IOP, Inherent Optical Property) 값을 이용하는 새로운 방법을 개발하였다. 각 방법은 한반도 주변 해역을 관측한 Sea Viewing Wide Field-of-view Sensor(SeaWiFS) 위성영상을 이용하여 적용하였다. 클로로필 농도 분포 영상을 만들어 본 결과 기존의 방법으로 얻기 어려웠던 탁도높은 해역과 에어로졸의 영향을 많이 받는 지역에서 보다 정확한 자료를 얻을 수 있었다.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.90-95
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• 2011

12-year LIDAR observations of tropospheric aerosol vertical distribution using a Mie scattering LIDAR in Hefei ($31.9^{\circ}N$, $117.2^{\circ}E$) from 1998 to 2009 are presented and analyzed in this paper. Characters of temporal variation and vertical distribution of tropospheric aerosol over Hefei are summarized from the LIDAR measurements. The impacts of natural source and human activities on the aerosol vertical distribution over Hefei could be seen clearly. Dust particles from the north in spring could affect the aerosol distributions below about 12 km over Hefei, and aerosol scale height in April reaches $2.29{\pm}0.68\;km$. Both LIDAR measurements and surface visibility imply that aerosols in the lower troposphere have been increasing since about 2005.

• 실내환경 및 냄새 학회지
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• 제16권1호
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• pp.47-53
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• 2017

Mold is one of the important bio-aerosols affecting human health in the indoor environment. To manage mold contamination, it is necessary to use an appropriate method for its detection and enumeration. Recently, the impaction method of ISO 16000-18 has been established as one of methods to detect and enumerate molds in air. To investigate the general use of the impaction method for mold detection in domestic indoor environments, the suitability of the method was assessed using different antibiotics, media and air samplers. All of the three antibiotics tested - ampicillin, chloramphenicol and streptomycin - showed inhibitory effects on bacterial colony formation on MEA and DG-18 media, without inhibiting mold growth. Of these three antibiotics, ampicillin was the most effective. There was no statistical difference between MEA and DG-18 media in the measurement of mold concentration. The formation of discriminative colony morphology was more apparent in DG-18 media. No significant difference in the measurement of mold concentration was found between Andersen samplers and MAS-100NT samplers, which are two major samplers introduced in Korea.

• 한국환경보건학회지
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• 제47권3호
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• pp.292-301
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• 2021

Objectives: Wearing medical masks has been recommended since the declaration of coronavirus disease-19 (COVID-19) as a pandemic disease. Certified medical masks are evaluated according to filtration efficiency and facial inhalation resistance. However, some people use non-certified common masks. This study aimed to evaluate various non-certified commercial masks based on the certification criteria for medical masks. Methods: Twenty mask products (three anti-droplet, three disposable dental, eight fashion, three cotton, and three children's masks) were selected. For performance evaluation, filtration efficiency and facial inhalation resistance tests were conducted. The evaluation method followed the certification method for KF-certified masks of the Ministry of Food and Drug Safety (MFDS) and the N95 respirator of the National Institute for Occupational Safety and Health (NIOSH). Results: None of the 20 masks met the KF94 certification standard set by the MFDS. Four and three masks respectively met the KF80 certification standard and the N95 standard of NIOSH. Filtration efficiency was significantly higher in three-layer masks than in single layer masks. Pleated-type masks had higher filtration efficiency than cone-type masks. There was no correlation between the structure of masks and facial inhalation resistance. Conclusion: While no masks complied with the KF94 certification standard, a few masks met the KF80 and the N95 certification standards of NIOSH. Although some people wear non-certified commercial masks, protection from aerosols is not guaranteed by such masks. Evaluation of the protection efficiency of non-certified mask against microbiological infection is needed for the prevention of infectious disease.

• 치위생과학회지
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• 제21권1호
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• pp.1-7
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• 2021

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted primarily through droplets, and dental practitioners are at risk of occupational exposure to SARS-CoV-2 infection owing to direct contact with the patient's mouth, aerosols from dental procedures, and saliva. Wearing a mask is believed to be the best method of protection against infection, and a systematic literature review was conducted on whether the dental masks used in dentistry are effective in preventing Coronavirus Infectious Disease-19 (COVID-19). Methods: We used PubMed, Google Scholar, DBpia, NDSL, and KISS databases for this study. Of the 917 documents narrowed down by the search terms "Coronavirus, COVID-19, and dental," 83 documents were collected and studied. Ultimately, 42 of these papers were selected for analysis after considering duplication from the flow chart of the literature selection process. Results: While dental masks are often used when treating patients with unknown COVID-19 status, the Ministry of Food and Drug Safety stated that the use of dental masks is insufficient in preventing cross-transmission of COVID-19; instead, it was recommended that N95 masks, which correspond to KF94 masks, should be worn daily. On the other hand, wearing a dental mask and following precautions such as hand hygiene may not pose a significantly higher risk of infection than wearing an N95 mask when treating COVID-19 patients. Conclusion: There is an ongoing discussion regarding the use of dental masks when treating dental patients, and many argue that different types of masks should be selected according to the degree of infection and the individual's respiratory condition. By considering the safety and efficacy of dental masks in preventing infection, improvements can be made in the management of COVID-19 and dental-related infections.