• 한국대기환경학회지
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• 제23권1호
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• pp.97-109
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• 2007

Vertical distribution and optical properties of atmospheric aerosols above the Korean peninsula are quite important to estimate effects of aerosol on atmospheric environment and regional radiative forcing. For the first time in Korea, vertical microphysical properties of atmospheric aerosol obtained by inversion algorithm were analyzed based on optical data of multi-wavelength Raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST). Data collected on 14 June 2004 at Gwangju ($35.10^{\circ}N,\;126.53^{\circ}E$) and 27 May 2005 at Anmyeon island ($36.32^{\circ}N,\;126.19^{\circ}E$) were used as raw optical data for inversion algorithm. Siberian forest fire smoke and local originated haze were observed above and within the height of PBL, respectively on 14 June 2004 according to NOAA/Hysplit backstrajectory analysis. The inversion of lidar optical data resulted in particle effective radii around $0.31{\sim}0.33{\mu}m$, single scattering albedo between $0.964{\sim}0.977$ at 532 nm in PBL and effective radii of $0.27{\mu}m$ and single scattering albedo between $0.923{\sim}0.924$ above PBL. In the case on 27 May 2005, biomass burning from east China was a main source of aerosol plume. The inversion results of the data on 27 May 2005 were found to be particle effective radii between $0.23{\sim}0.24{\mu}m$, single scattering albedo around $0.924{\sim}0.929$ at 532 nm. Additionally, the inversion values were well matched with those of Sun/sky radiometer in measurement period.

• 한국대기환경학회지
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• 제24권6호
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• pp.629-640
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• 2008

This study investigates long-term trends and characteristics of aerosol optical depth ($\tau_a$) and Angstrom exponent (${\AA}$) around Korea in order to understand aerosol effects on the regional climate change. The analysis period is mainly from 1999 to 2006, and the analysis sites are Anmyun and Gosan, the background monitoring sites in Korea, and two other sites of Xianghe in China and Shirahama in Japan. The annual variations of $\tau_a$ at Anmyun and Gosan have slightly systematic increasing and decreasing trends, respectively. $\tau_a$ at Anmyun shows more substantial variation, probably because of it's being closer and vulnerable to anthropogenic influence from China and/or domestic sources than Gosan. Both values at Gosan and Anmyun are approximately 1.5 times greater than those at Shirahama. The monthly variation of $\tau_a$ exhibits the highest values at late Spring and the lowest at late-Summer, which are thought to be associated with the accumulation of fine aerosol formed through the photochemical reaction before the Jangma period and the scavenging effect after the Jangma period, respectively. Meanwhile, the episode-average $\tau_a$ for the Yellow dust period increases 2 times greater than that for the non-Yellow dust period. A significant decrease in ${\AA}$ for the Yellow dust period is attributable to an increase in the loading of especially the coarse particles. Also we found no weekly periodicity of $\tau_a$'s, but distinct weekly cycle of $PM_{10}$ concentrations, such as an increase on weekdays and a decrease on weekends at Anmyun and Gosan. We expect these findings would help to initiate a study on aerosol-cloud interactions through the combination of surface aerosol and satellite remote sensing (MODIS, Calipso and CloudSat) in East Asia.

• Asian Journal of Atmospheric Environment
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• 제10권3호
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• pp.125-136
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• 2016

In this study, the effects of the mesh barrier on the free dispersion of ammonia were numerically investigated under different atmospheric conditions. This study presents the detail and flow feature of the dispersion of ammonia through the mesh barrier on various free stream conditions to decline and limit the toxic danger of the ammonia. It is assumed that the dispersion of the ammonia occurred through the leakage in the pipeline. Parametric studies were conducted on the performance of the mesh barrier by using the Reynolds-averaged Navier-Stokes equations with realizable k-${\varepsilon}$ turbulence model. Numerical simulations of ammonia dispersion in the presence of mesh barrier revealed significant results in a fully turbulent free stream condition. The results clearly show that the flow behavior was found to be a direct result of mesh size and ammonia dispersion is highly influenced by these changes in flow patterns in downstream. In fact, the flow regime becomes laminar as flow passes through mesh barrier. According to the results, the mesh barrier decreased the maximum concentration of the ammonia gas and limited the risk zone (more than 500 ppm) lower than 2 m height. Furthermore, a significant reduction occurs in the slope of the upper boundary of $NH_3$ risk zone distribution at downstream when a mesh barrier is presented. Thus, this device highly restricts the leak distribution of ammonia in the industrial plan.

• Asian Journal of Atmospheric Environment
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• 제11권3호
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• pp.202-216
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• 2017

Nitrogen (N) is an essential macronutrient. Thus, evaluating its flows and stocks in rice paddy ecosystems provides important insights into the sustainability and environmental loads of rice production. Among the N sources of paddy fields, atmospheric deposition and irrigation inputs remain poorly understood. In particular, insufficient information is available for atmosphere-rice paddy exchange of gaseous and particulate reactive N (Nr, all N species other than molecular N) which represents the net input or output through dry deposition and emission. In this study, we assessed the N inputs via atmospheric deposition and irrigation to a Japanese rice paddy area by weekly monitoring for 2 years with special emphasis on gas and particle exchange. The rice paddy during the cropping season acted as a net emitter of ammonia ($NH_3$) to the atmosphere regardless of the N fertilizer applications, which reduced the effects of dry deposition to the N input. Dry N deposition was quantitatively similar to wet N deposition, when subtracting the rice paddy $NH_3$ emissions from N exchange. The annual N inputs to the rice paddy were 3.2 to $3.6\;kg\;N\;ha^{-1}\;yr^{-1}$ for exchange, 8.1 to $9.8\;kg\;N\;ha^{-1}\;yr^{-1}$ for wet deposition, and 11.1 to $14.5\;kg\;N\;ha^{-1}\;yr^{-1}$ for irrigation. The total N input, 22.8 to $27.5\;kg\;N\;ha^{-1}\;yr^{-1}$, corresponded to 38% to 55% of the N fertilizer application rate and 53% to 67% of the brown rice N uptake. Monitoring of atmospheric deposition and irrigation as N sources for rice paddies will therefore be necessary for adequate N management.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.467-470
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• 2006

Geostationary Ocean Color Imager (GOCI) onboard its Communication Ocean and Meteorological Satellite (COMS) is scheduled for launch in 2008. GOCI includes the eight visible-to-near-infrared (NIR) bands, 0.5km pixel resolution, and a coverage region of 2500 ${\times}$ 2500km centered at 36N and 130E. GOCI has had the scope of its objectives broadened to understand the role of the oceans and ocean productivity in the climate system, biogeochemical variables, geological and biological response to physical dynamics and to detect and monitor toxic algal blooms of notable extension through observations of ocean color. To achieve these mission objectives, it is necessary to develop an atmospheric correction technique which is capable of delivering geophysical products, particularly for highly turbid coastal regions that are often dominated by strongly absorbing aerosols from the adjacent continental/desert areas. In this paper, we present a more realistic and cost-effective atmospheric correction method which takes into account the contribution of NIR radiances and include specialized models for strongly absorbing aerosols. This method was tested extensively on SeaWiFS ocean color imagery acquired over the Northwest Pacific waters. While the standard SeaWiFS atmospheric correction algorithm showed a pronounced overcorrection in the violet/blue or a complete failure in the presence of strongly absorbing aerosols (Asian dust or Yellow dust) over these regions, the new method was able to retrieve the water-leaving radiance and chlorophyll concentrations that were consistent with the in-situ observations. Such comparison demonstrated the efficiency of the new method in terms of removing the effects of highly absorbing aerosols and improving the accuracy of water-leaving radiance and chlorophyll retrievals with SeaWiFS imagery.

• 한국통신학회논문지
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• 제39B권12호
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• pp.856-863
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• 2014

지상 광무선 통신에서 대기의 교란 및 대기 입자에 의한 광의 감쇄가 있을 때, 대기교란의 강도 및 가시도가 수신 광 강도에 미치는 영향을 해석하였다. 광신호는 On-Off Keying(OOK), Pulse Position Modulation(PPM) 및 Digital Pulse Interval Modulation(DPIM)의 방식으로 변조하였다. 교란대기 하에서 각 변조방식에 대해 광 전송 거리에 따른 광수신 전력을 계산하고 이를 이용하여 전송거리에 따른 패킷 오류율(packet error rate: PER)을 계산하였다. 광신호를 전송하기 위한 광원의 파장은 850nm, 1310nm 및 1550nm을 선택하였다. 대기는 약 교란 상태로 가정하여 대기 굴절률 구조상수 $Cn2{\approx}10-14m-2/3$, 대기의 가시도 V=2km로 하였다. 약교란 대기 상태에서 세가지 변조방식 중 DPIM 방식이 우수하며, 광 신호의 전송을 위한 파장으로는 1550nm가 PER 성능이 우수함을 알 수 있었다.

• 한국환경과학회지
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• 제19권7호
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• pp.861-869
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• 2010

The present study aims to evaluate the characteristics of atmospheric polycyclic aromatic hydrocarbons (PAHs) pollution in roadside and residential areas of two Korean metropolitan cities (Seoul and Incheon) and a background area (Seokmolee). This purpose was established by analyzing temporal and spacial concentration distribution of total and 7 individual PAHs, which were extracted from ambient particulate matters, and by utilizing a multivariate statistical method (principal component analysis, PCA) for the qualitative determination of potential PAH sources. Target PAHs included benzo(a)anthracene (BaA), benzo(a)pyrene (BaP), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), chrysene (Chr), dibenzo(a,h)anthracene (DahA), and indeno(1,2,3-cd)pyrene (IcdP). For all surveyed sites, the concentrations of total PAHs were higher in winter season than in other seasons. However, the concentrations of individual PAHs varied with surveyed sites. In both residential and roadside sites of Seoul and Incheon, BbF revealed the highest atmospheric levels. For all 7 target PAHs, the ambient concentrations were higher in Seoul and Incheon than in a background area (Seokmolee). In both residential and roadside areas, the concentrations of 4 target PAHs (BaA, BbF, BkF, DahA) were higher in Incheon than in Seoul. However, both the residential and roadside Chr concentrations were comparable in Seoul and Incheon. In addition, the residential IcdP concentrations were higher in Incheon than in Seoul, whereas the roadside concentrations were higher in Seoul. The roadside and residential BaP concentrations exhibited the reverse result to the IcdP concentrations. An PCA analysis suggested that atmospheric PAHs in both residential and roadside areas would be due to combined effects of several potential sources such as gasoline- and diesel-fueled vehicles, coal/oil combustion, and waste incineration.

• Asian Journal of Atmospheric Environment
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• 제5권2호
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• pp.65-78
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• 2011

Ozone ($O_3$) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of $O_3$ has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of $O_3$ on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of $O_3$ impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of $O_3$ on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to $O_3$ of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of $O_3$ in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high $O_3$ sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to $O_3$ of Japanese larch and increase that of Japanese beech. To establish the critical level of $O_3$ for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of $O_3$ and other environmental factors such as elevated $CO_2$ and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of $O_3$ and any other abiotic environmental factors on Japanese forest tree species.

• 한국대기환경학회지
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• 제28권2호
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• pp.211-221
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• 2012

The Ministry of Environment will enforce air quality standards for $PM_{2.5}$ in 2015 because it affects human health as well as climate change and brings about other adverse effects. Until recently, even though a number of researches have reported $PM_{2.5}$ emissions according to sources, they have not precisely considered the emission factors correspondent to each source for emission estimation. For the sake of establishing $PM_{2.5}$ emission inventories, this study was undertaken using activity data of each source taken from CAPSS (Clean Air Policy Support System) multiplied by each emission factor of U.S. EPA Speciate or EEA CORINAIR. The 2008's total annual $PM_{2.5}$ emission (73.971 ton/yr) can be apportioned into five sources, such as fuel combustion facilities (62.2%), mobiles (33.8%), production processes (3.2%), fires (0.4%), and waste treatments (0.3%). The results show that fuel combustion facilities and mobiles are the predominant sources of $PM_{2.5}$, and they should be taken into great account in establishing $PM_{2.5}$ standards. In addition, it is necessary and urgent to develop effective measures for reduction of $PM_{2.5}$ emissions from those two main sources as well.

• 한국과학교육학회지
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• 제19권2호
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• pp.217-228
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• 1999

구성주의 관점에 의하면 학습자가 백지상태인 채 피동적으로 새로운 개념을 받아들이는 것이 아니라, 주체적인 입장에서 자기의 개념을 재조직해 가는 것이 학습의 과정이라고 본다. 본 연구에서는 이러한 구성주의 교수원리에 근거하여 예측 설명-실험, 관찰토론-적용 단계의 구성주의적 수업을 개발하고 이를 중학교 과학 수업에 적용하여 그 효과를 조사하였다. 2학년의 '대가와 물의 순환' 단원 총 7차시에 대하여 구성주의적 수업과 교사중심 수업을 실시한 후 대기압 관련 오개념 감소율과 학습동기의 4가지 요소 별로 비교하였다. 구성주의적 수업과 교사중심 수업이 대기압 관련 오개념 감소에 미치는 효과를 검증한 결과, '기온과 기압의 관계', '높이에 따른 기압의 변화', '대류현상과 기압', '기압과 바람' 등의 개념에서 나타난 오개념이 교사중심 수업보다 구성주의적 수업에서 더 많이 감소하였다. 또한 두 집단의 대기 압 개념 점수를 차이 검증한 결과 구성주의적 수업 집단이 교사중심 수업 집단에 비하여 유의미하게 높게 나타났다. 동기의 4가지 요소인 '주의력, '관련성', '자신감', '만족감' 각 문항의 점수를 비교한 결과 구성주의적 수업은 교사중심 수업보다 자신감 요소를 제외한 3가지 요소 모두에 효과적인 것으로 나타났다. 이것으로 구성주의적 수업에서 학습자들로 하여금 자신의 선행개념을 확인하고, 관찰과 토론을 통해 개념을 형성하도록 한 결과 교사중심 수업보다 과학개념 획득과 학습동기 유발에 효과적이라는 결론을 얻을 수 있다.