• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.444-450
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• 2010

The traditional approach to inverting aerosol extinction makes use of the assumption of a constant LIDAR ratio in the entire Mie-LIDAR signal profile using the Fernald method. For the large uncertainty in the cloud optical depth caused by the assumed constant LIDAR ratio, an not negligible error of the retrieved aerosol extinction below the cloud will be caused in the backward integration of the Fernald method. A new algorithm to determine aerosol extinction below a cirrus cloud from Mie-LIDAR signals, based on a new cloud boundary detection method and a Mie-LIDAR signal modification method, combined with the backward integration of the Fernald method is developed. The result shows that the cloud boundary detection method is reliable, and the aerosol extinction below the cirrus cloud found by inverting from the modified signal is more efficacious than the one from the measured signal including the cloud-layer. The error due to modification is less than 10% taken in our present example.

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.185-189
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• 2010

A micro-pulse LIDAR system (MPL) was employed to measure the aerosol over Pudong, Shanghai from July 2008 to January 2009. Based on Fernald method, aerosol optical variables such as extinction coefficient were retrieved and analyzed. Results show that aerosol exists mainly in low layers; aerosol loading reaches its maximum in the afternoon, and then decreases with time until its minimum at night. Most of the aerosol concentrates in the layer below 3 km, and optical extinction coefficient in the layer below 2 km contributes 84.25% of that below 6 km. Two extinction coefficient peaks appear in the near surface layer up to 500 m and in the level around 1000 m. Aerosol extinction coefficient shows a seasonal downward trend from summer to winter.

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.209-215
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• 2011

A new iterative algorithm is developed to estimate LIDAR ratio for a thin cirrus cloud over an aerosol layer. First, the thin cirrus cloud is screened out and replaced by a modeled LIDAR signal and the extinction coefficients of the aerosol layer are derived using the Fernald backward method. These aerosol coefficients are referred as the "actual values". Second, the original LIDAR signal which includes the thin cirrus cloud is also inverted by the Fernald backward method down to the aerosol layer but using different LIDAR ratio for the thin cirrus cloud. Depending on the different assumptions about the LIDAR ratio of the thin cirrus cloud, different sets of aerosol extinction can be derived. The "actual values" which are found in the first step can be used to constrain this iterative progress and the correct LIDAR ratio of the thin cirrus cloud can be found. The detailed description of this method and retrieval examples are given in the paper. The cases compared with other methods are presented and the statistical result is also shown and agrees well with other studies.

• KSBB Journal
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• 제22권2호
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• pp.78-83
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• 2007

제주도 자생식물의 80% 메탄올 추출물 10종의 항균 효과 및 항산화 효과를 검색하였다. 실험 대상 식물은 생체 채집하여 음건한 후 세절하여 80% 메탄올로 추출하여 추출된 시료를 10% 농도로 희석한 후 어류 질병미생물에 대한 항균실험을 하였고 80% 메탄올 추출물에 대한 항산화 실험은 각각의 시료를 0.1%, 0.5%, 0.8%, 1.0%, 2.0%로 희석하여 각 식물의 항산화 효과를 측정하였다. 항균 실험은 어류 질병미생물로 분류된 그람 음성균 12종과 그람 양성균 1종에 대하여 디스크 확산법으로 측정하였는데 그 결과 두메꿀풀 꽃과 잎 추출물에서 가장 강한 항균 효과를 나타내었고 다음으로 풀고사리 잎과 돌잔고사리 잎, 들깨 잎, 들깨 열매 순으로 나타났으며 큰천남성 뿌리나 왕모시풀 잎, 열매에서는 눈에 띄는 항균 효과를 나타내지는 않았다. 그리고 항산화 효과를 측정하기 위해 DPPH radical 소거능과 SOD 유사활성, Hyoxyl radical 소거 활성을 실험하였다. 각 식물의 80% 메탄올 추출물을 농도별로 희석하여 측정 한 결과 농도가 높아질수록 항산화 효과가 증가하는 것을 확인 할 수가 있었으며 2.0% 농도에서 두메꿀풀 잎과 열매 그리고 들깨 잎과 열매, 돌잔고사리 잎은 합성 항산화제인 BHT, BHA와 활성을 비교하여 보았을 때 BHT, BHA보다 높거나 유사한 항산화 효과를 나타내었다.

• KSBB Journal
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• 제21권2호
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• pp.164-169
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• 2006

제주도 자생식물의 열수 추출물 10종의 항균 효과 및 항산화 효과를 검색하였다. 실험 대상 식물은 생체 채집하여 음건 한 후 열수 추출하여 시료화하여 어류 질병미생물에 대한 항균실험과 각 식물의 열수 추출물의 항산화 효과를 측정 하였다. 항균 실험은 어류 질병미생물로 분류된 그람 음성균 12종과 그람 양성균 1종에 대하여 디스크 확산법으로 측정하였는데 그 결과 두메꿀풀 꽃 추출물에서 가장 강한 항균효과를 나타내었고 다음으로 풀고사리 잎과 돌잔고사리 잎, 들깨 잎, 들깨 열매 순으로 나타났으며 큰천남성 뿌리나 왕모시풀 잎, 열매에서는 눈에 띄는 항균 효과를 나타내지는 않았다. 그리고 항산화 효과를 측정하기 위해 DPPH radical 소거능과 SOD 유사활성, Hydroxyl radical 소거 활성을 실험하였다. 각 식물의 열수 추출물을 농도별로 희석하여 측정한 결과 농도가 높아질수록 항산화 효과가 증가하는 것을 확인 할 수가 있었으며 2.0%(20 mg/ml)농도에서 두메꿀풀 잎과 열매 그리고 들깨 잎과 열매, 돌잔고사리 잎은 합성 항산화제인 BHT, BHA와 높거나 유사한 항산화 효과를 나타내었다.

• Current Optics and Photonics
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• 제2권2호
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• pp.119-124
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• 2018

The errors in retrieved aerosol backscattering coefficients due to different lidar ratios are analyzed quantitatively in this paper. The actual calculation shows that the inversion error of the aerosol backscattering coefficients using the Fernald backward-integration method increases with increasing inversion distance. The greater the error in the lidar ratio, the faster the error in the aerosol backscattering coefficient increases. For the same error in lidar ratio, the smaller actual aerosol backscattering coefficient will get the larger relative error of the retrieved aerosol backscattering coefficient. The errors in the lidar ratios for dust or the cirrus layer have great impact on the retrievals of backscattering coefficients. The interval between the retrieved height and the reference range is one of the important factors for the derived error in the aerosol backscattering coefficient, which is revealed quantitatively for the first time in this paper. The conclusions of this article can provide a basis for error estimation in retrieved backscattering coefficients of background aerosols, dust and cirrus layer. The errors in the lidar ratio of an aerosol layer influence the retrievals of backscattering coefficients for the aerosol layer below it.

• 대기
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• 제20권4호
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• pp.483-494
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• 2010

The vertical profiles of the extinction coefficient, the backscatter coefficient, and the lidar ratio (i.e., extinction-to-backscattering ratio) for Asian dust and pollution aerosols are determined from Raman (inelastic) and elastic backscatter signals. The values of lidar ratios during two polluted days is found between 52 and 82 sr (July 22, 2009) and 40~60 sr (July 31, 2009) at 52 nm, with relatively low value of particle depolarization ratio (<5%) and high value of sun photometer-derived Angstrom exponent (> 1.2). However, lidar ratios between 25 and 40 sr are found during two Asian dust periods (October 20, 2009 and March 15, 2010), with 10~20% of particle depolarization ratio and the relatively low value of sun photometer-derived Angstrom exponent (< 0.39). The lidar ratio, particle depolarization ratio and color ratio are useful optical parameter to distinguish non-spherical coarse dust and spherical fine pollution aerosols. The comparison of aerosol extinction profiles determined from inelastic-backscatter signals by the Raman method and from elastic-backscatter signals by using the Fernald method with constant value of lidar ratio (50 sr) have shown that reliable aerosol extinction coefficients cannot be determined from elastic-backscatter signals alone, because the lidar ratio varies with aerosol types. A combined Raman and elastic backscatter lidar system can provide reliable information about the aerosol extinction profile and the aerosol lidar ratio.