http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Retrieval of Aerosol Extinction in the Lower Troposphere Based on UV MAX-DOAS Measurements
Lee, Hanlim,Irie, H.,Kim, Young J.,Noh, Youngmin,Lee, Chulkyu,Kim, Yeosook,Chun, Kee J. Taylor Francis 2009 AEROSOL SCIENCE AND TECHNOLOGY Vol.43 No.5
<P> Multi Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) has been utilized in recent years as a means of deriving vertical profiles of aerosol and trace gases; however, this new technique requires further validation because few studies have investigated its capability. In this study, vertical distributions of aerosol extinction coefficients (AECs) in the lower troposphere were retrieved by applying a recently developed aerosol-retrieval algorithm to O4 slant column densities (SCDs) measured at a UV wavelength (356 nm) using the MAX-DOAS technique. The MAX-DOAS measurements were conducted at the Korea Global Atmosphere Watch Observatory (KGAWO) located off the west coast of Korea during a period of seven cloudless days in May and June 2005. The AECs measured by UV MAX-DOAS varied from 0.05 to 0.73 km-1 in the 0-1 km layer and from 0.01 to 0.20 km-1 in the 1-2 km layer. The AECs for the 1-2 km layer from UV MAX-DOAS are in agreement with lidar data within about 60%. Our results demonstrate the ability of MAX-DOAS as a remote sensing technique for surface aerosol measurements.</P>
Lee, Chulkyu,Choi, Yeo Jin,Jung, Jin Sang,Lee, Jeong Soon,Kim, Ki Hyun,Kim, Young Joon Elsevier 2005 Atmospheric environment Vol.39 No.12
<P><B>Abstract</B></P><P>A Long Path DOAS system (GIST LP-DOAS) developed by GIST has been used to simultaneously measure atmospheric monoaromatic hydrocarbons (MAHC) and other trace compounds. The validity of GIST LP-DOAS in measuring atmospheric MAHC was tested over 740m beam paths at an urban site in Seoul, Korea, during two field campaigns held in February 2003. In order to remove the effects of interfering compounds (such as oxygen, ozone, and sulfur dioxide), two oxygen optical density spectra at two path lengths and the reference spectra of sulfur dioxide and ozone were incorporated in the fitting procedure for the determination of MAHC. The mean concentrations of MAHC measured with LP-DOAS system during the measurement period were 0.77 (benzene), 3.68 (toluene), 0.41 (<I>p</I>-xylene), and 0.54ppbv (<I>m</I>-xylene), respectively. The results of our LP-DOAS measurements were compared with those obtained by a collocated on-line Gas Chromatography (on-line GC) system. The concept of a percent difference (PD) and linear regression methods were employed to explain the bias structure between LP-DOAS and on-line GC. The results of this comparative analysis indicated that both systems exhibited strong compatibility with relatively good correlation. According to our correlation analysis between PD values and meteorological parameters, the compatibility between the two systems increased under the conditions of improved visibility and meteorological homogeneity (wind speed >1.3ms<SUP>−1</SUP>). Based on our study, it is concluded that the LP-DOAS system can be used to provide reliable information on both mixing ratios and temporal distribution characteristics of MAHC in urban air.</P>
인공위성(SCIAMACHY) 데이터를 이용한 대류권 SO₂, NO₂ 측정
이철규(Chulkyu Lee),Andreas Richter,John P. Burrows,김영준(Young J. Kim) 한국대기환경학회 2008 한국대기환경학회지 Vol.24 No.2
Anthropogenic emissions of nitrogen oxides and sulfur dioxide in Northeast Asia are of great concern because of their impact on air quality and atmospheric chemistry on regional and intercontinental scales. Satellite remote sensing based on DOAS (Differential Optical Absorption Spectroscopy) technique has been preferred to measure atmospheric trace species and to investigate their emission characteristics on regional and global scales. Absorption spectra obtained by the satellite-born instrument, SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) have been utilized to retrieve the information of SO₂ and NO₂ over Northeast Asia. SO₂ levels over Northeast Asia were in order of East China, Yellow Sea, South Sea and Korean Peninsula with mean vertical columns of 1.78(±1.0)×10<SUP>16</SUP>, 1.11(±0.67)×10<SUP>16</SUP>, 0.60(±0.63)×10<SUP>16</SUP>, 0.71(±0.65)×10<SUP>16</SUP> molecules/㎠, respectively. NO₂ levels were in order of East China, Yellow Sea, Korean Peninsula, and South Sea with mean vertical columns of 1.2(±0.56)×10<SUP>16</SUP>, 0.38(±0.19)×10<SUP>16</SUP>, 0.48(±0.28)×10<SUP>16</SUP>, 0.26(±0.16)×10<SUP>16</SUP> molecules/㎠, respectively. High levels of SO₂ and NO₂ were observed over East China, in particular in winter by the contribution of heating fuel combustion exhausts. The SO₂ and NO₂ levels over East China were the highest in January with 34% and 42% higher over the annual means. Low levels of SO₂ ranged over Korean peninsula, while NO₂ levels were relatively high, in particular in winter. The SO₂ and NO₂ levels over Yellow Sea were relatively higher compared to those over Korean peninsula and South Sea, which could be mainly attributed to their transport from East China.
실시간 데이타베이스 시스템에서 트랜잭션 분류에 의한 2 - Version 동시성 제어 기법
류철규(Chulkyu Ryu),이석훈(Seokhoon Lee),이승룡(Sungyoung Lee) 한국정보과학회 1995 한국정보과학회 학술발표논문집 Vol.22 No.2A
본 논문에서는 실시간 데이타베이스 시스템에서 우선순위가 낮은 트랜잭션들의 빈번한 취소를 줄이면서 병행수행 정도를 향상시킬 수 있는 2-version 동시성 제어기법을 제안한다. 제안한 스케쥴링은 트랜잭션의 특성에 따라 판독전용, 갱신전용 트랜잭션으로 분류하고 2-version 을 사용해 아주 긴 판독전용 트랜잭션이 갱신 트랜잭션에 의해 취소되지 않게 하는 방법이다. 본 논문은 이러한 기법을 통합 실시간 특킹 프로토콜[1]에 적용시켜, 우선순위가 높은 트랜잭션에 의해 우선순위가 낮은 트랜잭션이 취소되는 횟수를 줄이고 병행수행 정도를 높여 보다 많은 트랜잭션이 시간적인 제약조건을 만족할 수 있도록 하였다. 성능평가 결과, 판독전용 트랜잭션의 취소가 감소되어 높은 병행수행 정도를 얻고 시스템의 성능이 향상되었다.
Lim, Hyunwoo,Lee, Hunwoo,Cho, Hyosung,Seo, Changwoo,Je, Uikyu,Park, Chulkyu,Kim, Kyuseok,Kim, Guna,Park, Soyoung,Lee, Dongyeon,Kang, Seokyoon,Lee, Minsik 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.
<P>Phase-contrast x-ray imaging (PCXI) is an emerging technology which allows for imaging of smaller features in the examined sample than conventional attenuation-based x-ray imaging with lower x-ray dose. In this work, we investigated a relatively simple approach to PCXI using a conventional x-ray grid, which has potential to open the way to further widespread use of the technique into many application fields. We performed a simulation using a useful PCXI software developed in our previous study to investigate the image characteristics. We also performed a preliminary experiment for PCXI using a table-top setup which consists of a focused-linear xray grid having a 200-lines/in strip density, a microfocus x-ray tube having a 55-mu m focal spot, and a CMOS-type flat-panel detector having a 49-mu m pixel resolution. We successfully extracted absorption, dark-field, and phase-contrast x-ray images of much enhanced visibility at a time from the raw image of the sample by Fourier analysis. Further, we made a composite image by combining the absorption image with the colored dark-field image and compared its image characteristic to that of the absorption image alone.</P>