• 한국해양공학회지
• /
• 제23권6호
• /
• pp.39-43
• /
• 2009

A flow and low temperature of deep seawater the biofouling properties in a seawater environment of different materials, such as a steel pipe, polyethylene pipe, and nylon net, used for ocean industries. Experiments in a real sea environment were performed to grasp the quantitative and qualitative biofouling from diatoms attached to materials by measuring the Chlorophyll-a density. Experimental samples were placed under five types of ocean environmental conditions and analyzed every month for five months. It is shown that the biofouling by diatoms was strongly affected by the seawater temperature for all of the experimental samples. It was found that diatoms mainly adhered to the nylon net, while crustaceans prefer polyethylene, under a high temperature condition. It is believed that the biofouling properties are strongly related to the surface roughness of a material. The biofouling under the low temperature condition of deep seawater was rare and stable for the experimental periods. The inside of a pipe conveying deep seawater can be presumed to remain clear without biofouling on the condition of a flow and low temperature of deep seawater.

• Ocean and Polar Research
• /
• 제35권2호
• /
• pp.147-155
• /
• 2013

The purpose of this study is to investigate seasonal difference in linear trends in satellite-derived chlorophyll-a concentration (Chl-a) and their related environmental changes in the South Sea of Korea (SSK) and East China Sea (ECS) for recent 15 years (Jan. 1998~Dec. 2012) by analyzing climatological data of Chl-a, Rrs(555), sea surface wind (SSW) and nutrient. A linear trend analysis of Chl-a data reveals that, during recent 15 years, the spring bloom was enhanced in most of the ECS, while summer and fall blooms were weakened. The increased spring (Mar. - May) Chl-a was associated with strengthened winter (Dec. - Feb.) wind that probably provided more nutrient into the upper ocean from the deep. The causes of decreased summer (Jun. - Aug.) Chl-a in the northern ECS were uncertain, but seemed to be related with the nutrient limitation. Recently (after 2006), low-salinity Changjiang diluted water in the south of Jeju and the SSK had lower phosphate that caused increase in N/P ratio with Chl-a decrease. The decreased fall (Sep. - Nov.) Chl-a was associated with weakened wind that tends to entrain less nutrient into the upper ocean from the deep. This study suggests that phytoplankton in the ECS differently changes in response to environmental changes depending on season and region.

• 한국환경과학회지
• /
• 제17권1호
• /
• pp.85-95
• /
• 2008

Temporal and spatial variabilities of chlorophyll a (Chl-a) in the northern East China Sea (ECS) are described, using both 8-day composite images of the SeaWiFS (Sea-viewing Wide Field-of-view Sensor) and in-situ data investigated in August and September during 2000-2005. Ocean color imagery showed that Chl-a concentrations on the continental shelf within the 50 m depth in the ECS were above 10 times higher than those of the Kuroshio area throughout the year. Higher concentrations (above $5mg/m^3$) of yearly mean Chl-a were observed along the western part of the shelf near the coast of China. The standard deviation also showed the characteristics of the spatial variability near $122-124^{\circ}E$, where the western region of the East China Sea was grater than that of the eastern region. Particularly the significant concentration of Chl-a, up to $9mg/m^3$, was found at the western part of $125^{\circ}E$ in the in-situ data of 2002. The higher Chl-a concentrations of in-situ data were consistent with low salinity waters of below 30 psu. It means that there were the close relationship between the horizontal distribution of Chl-a and low salinity water.

• 한국물환경학회지
• /
• 제30권3호
• /
• pp.329-339
• /
• 2014

This study aims to estimate chlorophyll-a concentration in rivers using multi-spectral RapidEye imagery and Spectral Mixture Analysis (SMA) and assess the applicability of SMA for multi-temporal imagery analysis. Comparison between images (acquired on Oct. and Nov., 2013) predicted and ground reference chlorophyll-a concentration showed significant performance statistically with determination coefficients of 0.49 and 0.51, respectively. Two band (Red-RE) model for the October and November 2013 RapidEye images showed low performance with coefficient of determinations ($R^2$) of 0.26 and 0.16, respectively. Also Three band (Red-RE-NIR) model showed different performance with $R^2$ of 0.016 and 0.304, respectively. SMA derived Chlorophyll-a concentrations showed relatively higher accuracy than band ratio models based values. SMA was the most appropriate method to calculate Chlorophyll-a concentration using images which were acquired on period of low Chlorophyll-a concentrations. The results of SMA for multi-temporal imagery showed low performance because of the spatio-temporal variation of each end members. This approach provides the potential of providing a cost effective method of monitoring river water quality and management using multi-spectral imagery. In addition, the calculated Chlorophyll-a concentrations using multi-spectral RapidEye imagery can be applied to water quality modeling, enhancing the predicting accuracy.

• 상하수도학회지
• /
• 제34권4호
• /
• pp.277-288
• /
• 2020

In this study, we performed algorithms to predict algae of Chlorophyll-a (Chl-a). Water quality and quantity data of the middle Nakdong River area were used. At first, the correlation analysis between Chl-a and water quality and quantity data was studied. We extracted ten factors of high importance for water quality and quantity data about the two weirs. Algorithms predicted how ten factors affected Chl-a occurrence. We performed algorithms about decision tree, random forest, elastic net, gradient boosting with Python. The root mean square error (RMSE) value was used to evaluate excellent algorithms. The gradient boosting showed 10.55 of RMSE value for the Gangjeonggoryeong (GG) site and 11.43 of RMSE value for the Dalsung (DS) site. The gradient boosting algorithm showed excellent results for GG and DS sites. Prediction value for the four algorithms was also evaluated through the Receiver operating characteristic (ROC) curve and Area under curve (AUC). As a result of the evaluation, the AUC value was 0.877 at GG site and the AUC value was 0.951 at DS site. So the algorithm's ability to interpret seemed to be excellent.

• Ocean and Polar Research
• /
• 제34권2호
• /
• pp.201-218
• /
• 2012

The purpose of this study is to investigate climatological variations from the sea surface temperature (SST), chlorophyll-a concentration (Chl-a), and phytoplankton size class (PSC), using NOAA AVHRR, SeaWiFS, and MODIS data in the South Sea of Korea (SSK) and East China Sea (ECS). 26-year monthly SST and 13-year monthly Chl-a and PSC data, separated by whole and nine-different areas, were used to understand seasonal and inter-annual variations. SST and Chl-a clearly showed seasonal variations: higher SST and Chl-a were observed during the summer and spring, and lower values occurred during the winter and summer. The annual and monthly SST over 26 years increased by $0.2{\sim}1.0^{\circ}C$. The annual and monthly Chl-a concentration over 13 years decreased by $0.2{\sim}1.1mg/m^3$. To determine more detailed spatial and temporal variations, we used the combined data with monthly SST, Chl-a, and PSC. Between 1998 and 2010, the inter-annual trend of Chl-a decreased, with decreasing micro- and nano-size plankton, and increasing pico-size plankton. In regional analysis, the west region of the study area was spatially and temporally correlated with the area dominated by decreasing micro-size plankton; while the east region was less sensitive to coastal and land effects, and was dominated by increasing pico-size plankton. This phenomenon is better related to one or more forcing factors: the increased stratification of ocean driven by changes occurring in spatial variations of the SST caused limited contributions of nutrients and changed marine ecosystems in the study area.

• 한국식품영양과학회지
• /
• 제30권4호
• /
• pp.732-738
• /
• 2001

두충잎에서 인간대장암에세포 HCT-116에 세포증식 억제효과를 나타내는 성분을 silica gel column chromatography TLC로 분리하고 HPLC로 정제한 다음 UV-visual spectro-photometer에 의한 흡수 spectra 특성 HPLC에 의한 retention time과 분리패턴 및 FAB/MS로 분자량을 잠정적으로 동정한 결과 TLC 상에서 분리된 Rf 0.19 band 의 화합물은 chlorophyll a에서 $Mg^{2+}$이 제거된 pheophytin a로 Rf 0.25 band의 화합물은 pyropheophytin a로 확인되었다. 동정된 화합물들의 암세포 억제작용을 확인하기 위해 두충잎의 petroleum ether extract column chromatography로 분리한 분획물 및 TLC에서 분리된 각 band들의 cytotoxic activity을 in vitro에서 HCT-116 cancer cell을 사용하여 측정한 결과 모든 시료에서 암세포 증식억제 현상을 보였으며 특히 Rf 0.19와 Rf 0.25 band에서 분리된 화합물들에서 강하게 나타났다. 이 결과로 볼 때 두충잎에서 분리한 클로로필 유도체는 인간대장암세포인 HCT-116 cell에 대해 강한 항암작용이 있는 것으로 생각된다.

• 스마트미디어저널
• /
• 제11권9호
• /
• pp.56-63
• /
• 2022

최근 기후변화에 의한 수온상승, 과다한 영양염류의 유입 및 하천환경의 변화로 인한 주요하천 및 호소에 대한 조류발생 빈도 및 범위가 증가하고 있다. 이상조류에는 녹조와 적조가 있다. 녹조현상은 물속의 클로로필(Chl-a) 등의 남조류가 과다 성장하여 물의 색이 짙은 녹색으로 변하는 현상으로, 미량의 냄새물질과 독소를 생성하여 수질악화와 식수안전에 대한 우려가 급증하고 있다. 본 연구는 생활주변 환경의 생태하천과 호소에서 측정된 수질정보를 원격지에서 1:1 실시간모니터링 및 제어하기 위하여 디지털트윈의 3D 가상세계를 구축하고, 사물인터넷(IOT) 센서기반의 수질정보 센서측정기를 개발하며, AI의 머신러닝 기반 수집데이터 분석을 토대로 녹조 등 수질오염의 발생원인과 확산패턴을 예측하여 조류경보와 수질예보를 할 수 있는 스마트 수질환경 서비스 플랫폼 구축을 제안하고자 한다.

• 한국식품조리과학회지
• /
• 제16권4호
• /
• pp.321-327
• /
• 2000

본 연구는 부추김치의 담금방법에 따른 부재료가 발효숙성에 미치는 영향을 알아보기 위하여 소금을 첨가한 처리구 A, 간장을 첨가한 처리구 B, 간장과 들깨가루를 첨가한 처리구 C, 멸치액젓을 첨가한 처리구 D, 멸치액젓과 찹쌀풀을 첨가한 거리구 E로 담금 즉시 1$0^{\circ}C$에서 43일간 발효시키면서 색과 조직특성을 알아본 결과는 다음과 같다. 1. 클로로필 및 카로티노이드의 잔존율은 발효숙성이 진행됨에 따라 감소하였다. 발효숙성이 진행됨에 따라 Hunter's color value에서 녹색도를 나타내는“a”값이 감소하였다. 특히 멸치액젓과 찹쌀풀을 첨가한 처리구 E의 녹색이 가장 감소하였다. 2. 수용성 펙틴과 고형분 함량은 전반적으로 발효숙성이 진행됨에 따라 점차로 증가하였는데. 대체로 처리구 B>C>D>E>A의 순이었다. 3. TDF 함량은 발효숙성 초기와 큰 차이가 없다가 발효숙성이 진행됨에 따라 서서히 감소하였다. TDF 함량에서는 큰 차이가 없었으나, SDF와 IDF의 조성에는 변화가 있었는데, 발효숙성 8일째에는 SDF 함량이 전반적으로 5배에서 7배로 증가하였다. 이상의 결과를 종합해 볼 때, 본 실험의 조건하에서 발효숙성은 처리구 B>C>E>D>A의 순으로 빨리 진행되어 간장은 부추김치의 발효숙성을 빠르게 하였으며, 들깨가루 첨가는 발효숙성 말기에 오히려 발효숙성을 촉진하였고, 멸치액젓과 찹쌀풀 첨가는 부추김치의 변색을 가장 빨리 유발하였다는 결과로 보아 담금방법에 따라 부추김치의 발효숙성 양상에 차이가 있음을 알 수 있었다. 따라서 부추김치 담그는 목적에 따라 부재료를 선택하는 것이 바람직할 것으로 생각된다.

• Ocean and Polar Research
• /
• 제38권1호
• /
• pp.1-19
• /
• 2016

Recently, there has been a growing interest in physical-biological ocean-modeling systems by communities in the fields of science and business. In this paper, we present preliminary results from a coupled physical-biological model for the Northwestern Pacific marginal seas. The ocean circulation component is an implementation of the Regional Ocean Modeling System (ROMS), and the lower trophic level ecosystem component is a Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model. The ROMS-NPZD coupled system, with a 25 km resolution, is forced by climatological atmospheric data and predicts the physical variables and concentrations of nitrate, phytoplankton, zooplankton, and detritus. Model results are compared with remote-sensed sea surface temperature and chlorophyll, and with climatological sea surface salinity and nitrate. Our model adequately reproduces the observed spatial distribution and seasonal variability of nitrate and chlorophyll concentrations as well as physical variables, showing a high correlation in the East Sea (ES) and Kuroshio/Oyashio Extension (KOE) region but relatively low correlation in the Yellow Sea (YS) and East China Sea (ECS). Although some deficiencies were found in the biological components, such as the over/underestimation of the intensity of phytoplankton blooms in the ES and KOE/the YS and ECS, our system demonstrates the capability of the model to capture and record dominant seasonal variability in physical-biological processes and this holds out the promise of coming to a better understanding of such processes and making better predictions .