• Environmental Analysis Health and Toxicology
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• 제13권1_2호
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• pp.43-53
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• 1998

Ambient air levels of polycyclic aromatic hydrocarbons(PAHs) are of concern because of their potential for adverse health effects including transformation of some of these substances to mutagens and carcinogens by mammalian microsomal enzyme system. Airbone particulate samples were collected by a conventional high-volume sampler and by an Anderson cascade impactor on 2 to 3 days in each month over a period of 1 year at a representative site of the heavy traffic area of Seoul from beptember 1994 to August 1995. Ten individual PAHs in sizable air particulates of each stage of two months were separated and analyzed by gas chromatography/mass spectrometry. As a results of analysis, the gross concentrations of PAHs in the fine and coarse particles were higher in the winter month than in the spring, followed in descending order by in the fall and summer. In a study of dependency of 10 PAHs compounds on size distribution of particles at heavy traffic area found that about 85% of the total PAHs content was associated with particles less than 2.0um (fine particles) in diameter of winter sampling period. while 79% were associated with this size fraction during summer period. In according to the mean concentrations of the 10 PAHs in 7 size classification from < 0.38 to> 10.1, the 'size was the smaller, PAHs concentration was the higher. Thus it was found that PAHs concentration was greatly affected by air particle size. Annual mean benzo(a)pyrene equivalents was 5.88ng/m$^3$ and obtained by applying, toxic equivalency factor developed by Nisbet and Lagoy.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.556-566
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• 2019

Recently, as the supply of residential polymer electrolyte membrane fuel cells (PEMFCs) increases, the durability and lifetime of the PEMFC system are becoming important. The related studies have been mainly focused on the durability and lifetime of materials while the research on the durability and maintenance of the system level is insufficient. In this paper, a model-based fault detection method is developed considering an air supply system that is dominant to the system performance and efficiency. A commercial 1 kW residential fuel cell system is built, and experiments are conducted under various operation loads and states (normal, 6 faults). From the experimental data, nominal models and residuals are generated. With the residual pattern obtained from real-time data, the detection and classification of various faults can be possible. The technical importance of this paper is to minimize extra sensor installation by using the empirical model rather than a complex mathematical model, and to decrease the number of models by using the applicable model at three loads. Finally, the model-based fault detection method for the air supply system of a PEMFC is established and is expected to be applicable to other subsystems.

• 한국조경학회지
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• 제45권4호
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• pp.131-142
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• 2017

본 연구에서는 동일한 열환경 특성을 가진 공간 분류와 관련하여 전 세계적으로 활용되고 있는 World Urban Database and Access Portal Tools(WUDAPT) protocol의 Local Climate Zone(LCZ) 분류체계 및 분류 방법론을 바탕으로 사례지역인 서울특별시의 도시기후구역 유형을 분류하고, 유형별 특징을 분석하였다. 이를 위해, 구글 어스(Google Earth)를 활용하여 서울특별시를 포함하는 분석 지역을 대상으로 17개 LCZ 유형별 10개의 훈련지역(training area)을 선정한 후 SAGA GIS에서 LCZ 분류 및 분석결과에 대한 보정(Filtering)을 실시하였다. 그 후, ArcGIS를 이용하여 적절한 보정 횟수 분석 및 LCZ 유형별 특징을 도출하였다. 분석 결과, 보정 횟수는 1회가 가장 적절한 것으로 파악되었다. 또한, 연 평균기온 및 최고평균기온이 다른 구에 비해 높은 구 중 양천구와 영등포구는 저층 건물이 밀집해 있으며, 녹지가 적은 LCZ 3과 고층건물이 일정한 간격으로 있으며, 녹지가 풍부한 LCZ 4 유형의 비율이 높은 것으로 나타났으며, 연 평균기온 및 최고평균기온이 다른 구에 비해 낮은 구 중 종로구, 은평구, 노원구, 관악구는 녹지가 많고, 자연피복으로 이루어진 LCZ A의 비율이 가장 높았다. LCZ 유형별 평균 건폐율, 불투수포장율 및 건물높이는 WUDAPT에서 제시하는 LCZ 유형별 특징의 범위에 속해 있으나, 투수포장율은 LCZ 4~6 및 9~10에서 그 범위를 벗어났다. 본 연구는 국내 도시를 대상으로 한 기존의 도시기후구역 분류 연구에서 활용하지 않았던 WUDAPT protocol의 LCZ 분류 방법론을 활용함으로써 기후구역 분류에 관한 새로운 방법론을 제시하였으며, 기후변화 적응에 관한 공간계획 및 정책수립 과정에서 열환경 요소를 보다 적극적으로 고려하는데 기여할 것으로 기대된다.

• 방송공학회논문지
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• 제26권6호
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• pp.809-812
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• 2021

PCB를 코팅하는 과정에서 기포가 발생하면 회로 오작동의 원인이 되기 때문에 기포 검출은 컨포멀 코팅 검사에서 매우 중요한 작업이다. 이전 연구에서는 기포의 밝기 특성을 이용하여 기포의 후보를 추출하고, 합성곱 신경망(CNN: Convolutional Neural Networks)을 이용하여 추출된 후보를 검증하였다. 본 논문에서는 전이학습 기반의 합성곱 신경망 모델을 이용하여 기포를 검출하는 방법을 제안한다. 이를 위해 합성곱 신경망 모델로 VGGNet을 사용하고, 분류층(Classification Layer)으로 시그모이드(Sigmoid)를 적용하였으며, 마지막 합성곱층(Convolutional Layer)과 분류층을 함께 학습하는 전이학습 방법을 적용하였다. 제안하는 방법의 기포 검출 성능은 F1-score 0.9044로서 이전 연구 대비 약 0.17의 개선 효과를 나타내었다.

• 한국항행학회논문지
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• 제25권6호
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• pp.576-581
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• 2021

고농도의 경우 저농도와 비교하였을 때, 발생 빈도수의 차이와 발생 환경에 대한 차이로 예측 성능의 한계를 두드러지게 보이고 있다. 이러한 문제를 해결하기 위해 본 논문에서는 인공신경망 알고리즘을 이용하여 저농도와 고농도로 분류하고 구분된 농도별로 특성을 학습시킨 두 가지 예측 모델을 통해 예측을 수행하는 모델을 제안하였다. 저농도와 고농도를 분류하기 위해 DNN 기반의 분류 모델을 설계하고 분류모델을 통해 구분된 저농도와 고농도를 기준으로 농도별 특성을 반영하기 위한 저농도 예측 모델과 고농도 예측 모델을 설계하였다. 농도별 예측 모델의 성능 평가 결과, 저농도 예측 정확도가 90.38%, 고농도 예측 정확도는 96.37% 의 예측 정확도를 보였다.

• 한국대기환경학회지
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• 제17권5호
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• pp.425-437
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• 2001

This study is based on the uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies between air pollutants exposure and childhood asthma. Studies for this meta-analysis were conducted by reviewing previous results and by asking researcher active in this field for recommendations. Overall, 10 cases of air pollutants exposures and childhood asthma were reviewed. A variety of statistical methods for meta-analysis have been used to assess the combined effects, to identify heterogeneity, and to provide a single summary risk estimate based on a set of simiar epidemiologic studies. In this study, classification of exposure metircs on air environmental epidemiologic studies are reported for (1) aggravation of childhood asthma by a 50 ppb increase SO$_2$(6 individual studies); (2) aggravation of childhood asthma by a 50 ppb increase NO$_2$(5 individual studies); (3) aggravation of childhood asthma by a 50 ppb increase $O_3$(7 individual studies); (4) aggravation of childhood asthma by a 10$\mu\textrm{g}$/m$^3$increase PM$_{10}$ (4 individual studies); (5) aggravation of childhood asthma by a 1 ppm increase CO (2 individual studies); and (6) comparison of results between a Korean study results and this meta-analytic study. Results of this study indicated that an inverse-variance weighted pooling of the hospital admission risk at a 1ppm increment of CO levels was 1.12% (95% CI : 1.01 ~ 1.24). The hospital admission risk was estimated to increase 5% (95% CI : 1.02~1.08), 6%(95% CI : 1.04~1.09), and 5% (95% CI : 1.02~1.09) with each 50ppb increase of SO$_2$, NO$_2$, and $O_3$, respectively. In addition, our results lead to a small but significant elevation in risk of 2% (RR = 1.02, 95% CI = 1.01~1.04) with each 10$\mu\textrm{g}$/m$^3$increase of PM$_{10}$ among 4 individual studies. We found a small elevation in risk of childhood asthma, and pooled results of 10 epidemiologic studies of childhood asthma using increase a cut-off-point levels of air pollutants showed a few pieces of evidence. The results of this meta-analysis suggested that air pollution associated with an increased incidence of childhood asthma. According to this study, relationship between exposure to air pollutants and childhood asthma in Korea seem to be high than results of this meta-analysis.sis.

• 한국대기환경학회지
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• 제22권5호
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• pp.661-678
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• 2006

Products developed in this research is a software which can transfer the type of shape(.shp) into the type of ascii using the land cover data and the topography data in the metropolitan area of Seoul. In addition, it can calculate the $CO_2$ flux according to distribution of plants within the land cover data. The $CO_2$ flux is calculated by the experimental equation which is compose of the meteorological parameters such as the solar radiation and the air temperature. The net flux was shown in about $-19ton/km^2$ by removing $CO_2$ through the photosynthesis during daytime, and in 2 ton/km2 by producing it through the respiration during nighttime on 10 August 2004, the maximum day of air temperature during the period of 3yr(2001 to 2004), in the metropolitan area of Seoul. Spatial distribution of the air temperature and the wind field is simulated by substituting the middle classification of the land cover map data, upgraded by the Korean Ministry of Environment(KME), for the land-use data of the United States Geological Survey(USGS) within the Meteorological Mesoscale Model Version 5(MM5) on 10 August 2006 in the metropolitan area of Seoul. Difference of the air temperature between both data was shown in the maximum range of $-2^{\circ}C\;to\;2.9^{\circ}C$, and the air temperature due to the land use data of KME was higher than that of USGS in average $0.4^{\circ}C$. Also, those of wind vectors were meanly lower than that of USGS in daytime and nighttime. Furthermore, the hourly time series of Volatile Organic Components(VOCs) is calculated by using the Biosphere Emission and Interaction System Version 2(BEIS2) including the new land cover data and the meteorological parameters such as the air temperature and so]ar insolation. It is possible to calculate the concentration of ozone due to the biogenic emission of VOCs.

• 자원리싸이클링
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• 제27권1호
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• pp.31-37
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• 2018

폐금속자원의 재활용률을 높이기 위해서는 섞여 있는 다양한 종류의 금속 스크랩을 자동으로 선별할 수 있는 금속 선별 시스템 개발이 요구된다. 레이저유도붕괴분광법(Laser induced breakdown spectroscpoy, LIBS)은 빠른 속도로 공기 중에서도 다원소 분석이 가능하여 실시간 선별이 가능한 측면에서 매우 우수한 기술로 여겨지고 있으며, 측정된 LIBS 데이터의 다변량 통계분석을 통해 분류 정확도를 크게 향상시킬 수 있다. 본 연구에서는 재활용 업체로부터 획득한 5종류의 현장 폐금속 시료의 LIBS 성분 분석을 진행하였다. 금속 종류별로 좀 더 정확한 선별을 위해 적합한 분광선의 선정을 토대로 다변량 통계분석법이 적용되었으며, 선정된 분광선들을 이용하여 높은 정확도와 속도로 분류가 가능한 것을 확인할 수 있었다. 본 연구를 토대로 LIBS 기술의 산업현장에서의 실시간 폐금속 선별 적용 가능성을 제시한다.

• 한국산업보건학회지
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• 제24권3호
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• pp.345-352
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• 2014

Objectives: This study is aimed to describe the current situation about urinary biomarker N-methylformamide(NMF) for workers exposed to N,N-dimethylformamide(DMF) according to industrial classification. Materials: Special health examination records of the workers who had undergone urinary biological monitoring in 2013 were collected. The numbers and percentage of workers, whose urinary NMF values were above the limit of detection(LOD) and above the biological exposure index(BEI) were calculated. Health relatedness with DMF as judged by their doctors was also described. All description was classified according to the $9^{th}$ Korean Standard Industrial Classification(KSIC). Results: It appeared that most workers exposed to DMF belong to manufacturing section(80.7%). The geometric mean(GM) values of urinary NMF were 6.25 mg/L, 3.54, and 3.86 for the manufacturing section, professional, scientific and technical activities section, and for the construction section respectively. In detail, it seemed that division of textiles(except apparel) (GM 7.51 mg/L), division of leather, luggage and footwear(11.59 mg/L), and division of rubber and plastic products(6.89 mg/L) were highly exposed to DMF with a high percentage of workers with urinary NMF values above BEI. This was probably due to the effect of skin absorption that the division of leather, luggage and footwear showed the highest urine NMF GM. Conclusions: It seemed that workers in manufacture industries such as textile, leather, luggage, footwear, rubber and plastic products were highly exposed to DMF. So, efforts should be focused on those industries in order to effectively diminish worker's exposure. Further studies to compare DMF air-monitoring with bio-monitoring according to industrial classification should be considered.

• 대기
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• 제16권1호
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• pp.33-48
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• 2006

A classification of snowfall type based on development mechanism is proposed using previous snowfall studies, operational experiences, etc. Five types are proposed: snowfall caused by 1) airmass transformation (AT type), 2) terrain effects in a situation of expanding Siberian High (TE type), 3) precipitation systems associated with extratropical cyclones (EC type), 4) indirect effects of extratropical cyclones passing over the sea to the south of the Korean peninsula (ECS type), and 5) combined effects of TE and ECS types (COM type). Snowfall events during 1981-2001 are classified according to the 5 types mentioned above. For this, 118 events, with at least one station with daily snowfall depth greater than 20 cm, are selected. For the classification, synoptic weather charts, satellite images, and precipitation data are used. For TE and COM types, local sea-level pressure chart is also used to confirm the presence of condition for TE type (this is done for events in 1990 and thereafter). The classification shows that 109 out of 118 events can be classified as one of the 5 types. In the remaining 8 events, heavy snowfall occurred only in Ullung Island. Its occurrence may be due to one or more of the following mechanism: airmass transformation, mesoscale cyclones and/or mesoscale convergence over the East Sea, etc. Each type shows different characteristics in location of snowfall and composition of precipitation (i.e., dry snow, rain, and mixed precipitation). The AT-type snowfall occurs mostly in the west coast, Jeju and Ullung Islands whereas the TE-type snowfall occurs in the East coast especially over the Young Dong area. The ECS-type snowfall occurs mostly over the southern part of the peninsula and some east cost area (sometimes, whole south Korea depending on the location of cyclones). The EC- and COM-type snowfalls occur in wider area, often whole south Korea. Precipitation composition also varies with the type. The AT-type has a snow ratio (SR) higher than the mean value. The TE- and EC-type have SR similar to the mean. The ECS- and COM-type have SR values smaller than the mean. Generally the SR values at high latitude and mountainous areas are higher than those at the other areas. The SR value informs the characteristics of the precipitation composition. An SR value larger than 10 means that all precipitation is composed of snow whereas a zero SR value means that all precipitation is composed of rain.