• Ocean and Polar Research
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• 제30권3호
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• pp.289-301
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• 2008

Community structure of heterotrophic protists and their grazing impact on phytoplankton were studied in Northwest Pacific Ocean during October, 2007. The study area was divided into four regions based on physical properties (temperature and salinity) and chlorophyll-a distribution. They were Region I of North Equatorial Currents, Region II of Kuroshio waters, Region III of shelf mixed water, and Region IV of Tsushima warm current from East China Sea. The distribution of chlorophyll-a concentrations and community structure of heterotrophic protists were significantly affected by physical properties of the water column. The lowest concentration of chlorophyll-a was identified in Region I and II, where pico-sized chlorophyll-a was most dominant (>80% of total chlorophyll-a). Biomass of heterotrophic protists was also low in Region I and II. However, Region III was characterized by low salinity and temperature and high chlorophyll-a concentration, with relatively lower pico-sized chlorophyll-a dominance. The Highest biomass of heterotrophic protists appeared in Region III, along with the relatively less important nanoprotists. In Region I, II and IV, heterotrophic dinoflagellates were dominant among the protists, while ciliates were dominant in Region III. Community structure varied with physical(salinity and temperature) and biological (chlorophyll-a) properties. Biomass of heterotrophic protists correlated well with chlorophyll-a concentration in the study area ($r^2=0.66$, p<0.0001). The potential effect of grazing activity on phytoplankton is relatively high in Region I and II. Our result suggest that biomass and size structure of heterotrophic protists might be significantly influenced by phytoplankton size and concentration.

• 대한원격탐사학회지
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• 제28권6호
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• pp.635-651
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• 2012

To produce a level-3 monthly composite image from daily level-2 Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll-a concentration data set in the East Sea, we applied four average methods such as the simple average method, the geometric mean method, the maximum likelihood average method, and the weighted averaging method. Prior to performing each averaging method, we classified all pixels into normal pixels and abnormal speckles with anomalously high chlorophyll-a concentrations to eliminate speckles from the following procedure for composite methods. As a result, all composite maps did not contain the erratic effect of speckles. The geometric mean method tended to underestimate chlorophyll-a concentration values all the time as compared with other methods. The weighted averaging method was quite similar to the simple average method, however, it had a tendency to be overestimated at high-value range of chlorophyll-a concentration. Maximum likelihood method was almost similar to the simple average method by demonstrating small variance and high correlation (r=0.9962) of the differences between the two. However, it still had the disadvantage that it was very sensitive in the presence of speckles within a bin. The geometric mean was most significantly deviated from the remaining methods regardless of the magnitude of chlorophyll-a concentration values. Its bias error tended to be large when the standard deviation within a bin increased with less uniformity. It was more biased when data uniformity became small. All the methods exhibited large errors as chlorophyll-a concentration values dominantly scatter in terms of time and space. This study emphasizes the importance of the speckle removal process and proper selection of average methods to reduce composite errors for diverse scientific applications of satellite-derived chlorophyll-a concentration data.

• Food Science and Biotechnology
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• 제16권2호
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• pp.205-211
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• 2007

This study was designed to investigate the suppressive effect of chlorophyll a on nitric oxide (NO) production and intracellular oxidative stress. In addition, chlorophyll a regulation of nuclear factor (NF) ${\kappa}B$ activation and inducible NO synthase (iNOS) expression were explored as potential mechanisms of NO suppression in a lipopolysaccharide (LPS)-stimulated macrophage cell line. RAW 264.7 murine macrophages were preincubated with various concentrations ($0-10\;{\mu}g/ mL$) of chlorophyll a and stimulated with LPS to induce oxidative stress and inflammatory response. Treatment with chlorophyll a reduced the accumulation of thiobarbituric acid-reactive substances (TBARS), enhancing glutathione level and the activities of antioxidative enzymes including superoxide dismutase, catalase, glutathione peroxidase (GSH-px), and glutathione reductase in LPS-stimulated macrophages compared to LPS-only treated cells. NO production was significantly suppressed in a dose-dependent manner (p<0.05) with an $IC_{50}$ of $12.8\;{\mu}g/mL$. Treatment with chlorophyll a suppressed the levels of iNOS protein and its mRNA expression. The specific DNA binding activities of NFkB on nuclear extracts from chlorophyll a treated cells were significantly suppressed in a dose-dependent manner with an $IC_{50}$ of $10.7\;{\mu}g/mL$. Chlorophyll a ameliorates NO production and iNOS expression through the down-regulation of NFkB activity, which may be mediated by attenuated oxidative stress in RAW 264.7 macrophages.

• 한국식품과학회지
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• 제19권6호
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• pp.463-470
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• 1987

건조 식품의 적절한 포장 기법을 확립하고 포장된 제품의 품질 변화를 신속하게 예측할 수 있는 방법을 개발하고자 건조 김을 모델 식품으로 하여 저장 온 습도 조건 및 포장재별로 수분활성도 및 품질 지표 물질로서 chlorophyll a의 변화를 simulation하고 shelf-life를 예측하였다. 수분활성도와 chlorophyll a의 반응 상수 사이의 수학적인 변화 모델을 $10^{\circ}C,\;25^{\circ}C$ 및 $40^{\circ}C$에서 설정하였다. 수분 함량. 저장 온 습도 및 포장재와 같은 저장 조건의 영향을 동시에 고려하여 제품의 수분활성도 및 품질 지표 물질인 chlorophyll a의 변화를 예측할 수 있는 컴퓨터 simulation 방법이 개발되었다. simulation에 의해 예측된 품질 변화는 실측치와 잘 일치하였다. 수분활성도가 증가함에 따라 기호도 및 chlorophyll a는 감소하였으며, 기호도와 chlorophyll a와의 상관관계도 매우 높아 상관계수는 0.991이었다. 관능검사에 의해 측정된 저장 임계 수분활성도는 약 0.55이었다. 여러 저장 조건에서 플라스틱 필름 포장된 건조 김의 shelf-life를 예측할 수 있었다.

• 한국식품영양과학회지
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• 제26권4호
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• pp.563-568
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• 1997

갓김치의 발효과정 중 chlorophylls, chlorophyll de-rivatives 및 carotenoids의 함량 변화와 갓김치에서 얻어진 이의 조획분의 항산화성을 살펴보았다. 갓김치 발효기간에 따른 chlorophylls 및 carotenoids의 함량은 발효 7일 동안 chlorophylls가 pheophytins로 급격히 전환되었으며 chlorophylls와 함께 chlorophyllides는 높은 농도는 아니지 만 15일 까지는 존재하다가 그 이후 모두 pheophytins와 pheophorbides로 변했다. 갓김치 발효기간 동안 total chlorophylls에는 큰 변화없이 거의 일정하게 유지 되었으나 carotenoids는 발효 말기인 25일째에 초기 함량의 43.7%로 감소되었다. 갓김치에서 얻어진 chlorophylls와 carotenoids 조분획이 지방질의 자동산화에 미치는 영향을 조사하였을 때 $\alpha$-tocophe-rol 보다 높은 항산화성을 나타내었으며 발효기간에 따른 갓김치의 항산화성을 비교하였을 때 유의적으로 차 이는 없었다. 갓김치의 chlorophylls와 carotenoids 분획이 지방산의 산화에 대한 저해작용을 나타내는 동안 chlorophylls와 caratenoids의 감소율을 비교했을 때 총 chlorophylls가 총 caratenoids 보다 안정성이 높았다.

• 한국환경과학회지
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• 제17권2호
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• pp.141-148
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• 2008

In order to investigate the effect of inflow of Yangze river on the distribution of chlorophyll-${\alpha}$, the results of serial oceanographic observation during 2000-2005 were used. The oceanographic conditions in the northern East China Sea is influenced by the Tsushima Warm Current and low saline water derived from the Yangze river. The distributions of these water masses vary significantly by the season in the northern East China Sea. The sea surface temperature and salinity were stable and concentrations of chlorophyll-${\alpha}$ were low in the eastern part of $126^{\circ}E$. On the contrary, the salinity was significantly influenced by the low saline water derived from Yangze river with the high concentrations of chlorophyll-${\alpha}$. It is suggested that the low saline water inflowed from the Yangze river affects high concentrations of chlorophyll-${\alpha}$ in the northern East China Sea in summer.

• Ocean Science Journal
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• 제42권1호
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• pp.49-59
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• 2007

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

• 한국물환경학회지
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• 제26권6호
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• pp.994-999
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• 2010

The toxin of Cyanobacteria (blue-green algae) during summer season has been a problem and early prevention should be considered. A variety of methods can be used to forecast algal blooms and this study aims at examining feasibility of chlorophyll-a. The real-time data were collected by automatic water quality monitoring system (AWQMS) in Daecheong reservoir and invalid data were sorted by experts. And then, the sorted data were filled using linear interpolation. When the concentration of chlorophyll-a increased by $15mg/m^3$, water temperature and pH exceeded $26.8^{\circ}C$ and 9.5 respectively. As a result of correlation between chlorophyll-a and other parameters(i.e. water quality items and hydrological data), temperature (r=0.502 - 0.574), pH (r=0.583 - 0.681), total organic carbon (TOC, r=0.583 - 0.681) comparably had higher values. Meanwhile, the data around a day or two showed the highest correlation. In addition, chlorophyll-a is considered to be significantly effected by precipitation and inflow.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.918-921
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• 2006

The short-term variation of sea surface temperature before and after typhoons and increase of chlorophyll a concentration that accompany with the typhoons during summer in the East/Japan Sea were explored by satellite. Four typhoons (NAMTHEUN, MEGI, CHABA and SONGDA) and a typhoon (NABI) passed over the East/Japan Sea in 2004 and 2005, respectively. Decreasing of SST was observed in the every five typhoons, however the magnitude of SST decreasing were various from 1 to $5^{\circ}C$. Chlorophyll a increases were found after the typhoons (0.1-3 ${\mu}g$ $l^{-1})$ except NAMTHEUN, and the area was approximately included in SST decreasing area by the typhoons. It suggests that chlorophyll a increase was caused by nutrient input from subsurface layer by strong mixing. On the other hand, rarely chlorophyll a increase was observed in northern area of polar frontal zone, which is located in $38-41^{\circ}N$, than northern area, and chlorophyll a increase in coastal area was higher (more than 3 times) than offshore area. It might suggest that chlorophyll a increase in the East/Japan Sea is also related with the depth or nitracline depth that affects the amount of nutrients supply to the upper layer by typhoon mixing.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.243-243
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• 2017

Leaf colors of rice can be used to identify stress level due to its adaptation to environmental change. For most leaves green-related colors are sourced from chlorophyll a and b. For most leaves green-related colors are consisted of chlorophyll a and b. Chlorophyll concentration is normally measured using a spectrophotometer in laboratory. In some remote observation fields, it is impossible to collect the leaves, preserve them, and bring them to laboratory to measure their chlorophyll content. The measurement of chlorophyll content is observed through its color. Using CIE chromaticity diagram leaf color information in RGB is transformed into wavelength (in nm). Pheophytin contents were also analyzed in 95% ethanol extracts. In the process of leaf development of rice young seedling, both pigments were compared. Leaf samples from different rice seedling bed is taken, their colors and RGB values are recorded using Photoshop Image Analysis. SPAD-502 values were also measured. The chlorophyll and Pheophytin contents were fully estimated by ${\rightthreetimes}_{avg}$ on CIE chromaticity diagram.