• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.213-230
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• 2017

The satellite-based red tide detection algorithms have been developed for specific occurrence waters and red tide species. However, it is essential to study the whole occurrence waters and various red tide species for quick and accurate surveillance of red tide around the Korean coastal waters. In thisstudy, the comprehensive analysesinvolve the spectral features of red tide areas and the suitability of the satellite-based red tide detection algorithms used with GOCI in the Korean coastal waters. As a result, the spectral characteristics were changed according to the chlorophyll content of red tide species and the turbidity of the waters where the red tide appeared. In addition, the previous red tide detection algorithm is applied to GOCI, and it is found that there is a limitation to the red tide area extraction as the existing threshold value. To overcome these limitations, red tide species were divided into two groups according to the difference of chlorophyll content and a system for red tide surveillance wassuggested. It is possible to distinguish between red tide and non-red tide area through five steps. As a result of applying to GOCI, the red tide was appropriately extracted from the previous algorithm based on red tide breaking news. If such a red tide surveillance system is used, it will be possible to efficiently monitor red tide by quick and accurate surveillance of the whole occurrence waters around the Korean and various red tide species.

• Journal of Soil and Groundwater Environment
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• v.11 no.4
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• pp.1-9
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• 2006

The purpose of this study is to evaluate laboratory experiments on arsenic and cadmium removal from tailings using apatite at the Ulsan Abandoned Iron Mine, and to develop a stabilization technique. The results of this study show that the permeability is decreased proportionally to the amount of apatite when it is added below 8%, while this is almost constant when the amount of apatite is added above 10%. The water extraction test from tailings using deionized water for several days shows that pH (7.4-8.4) is almost constant or slightly increased when apatite is added below 8%, while it is slightly decreased when apatite is added above 10%. According to TCLP test, reduction of concentrations of heavy metals in leachate is proportional to amount of apatite added. It seems that precipitates generated from leachate-apatite chemical reaction are not redissolved. As a result, cadmium and arsenic in leachate is mostly removed when apatite is added above 10%, and it is suggested that a proper technique should be selected for field application because either mixed or layered method shows almost same removal efficiencies of cadmium and arsenic in tailings.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.46-53
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• 2012

In this study, mechanical tests and microstructural analyses including TEM analyses with EDX of precipitates in modified 9Cr-1Mo steel were carried out to determine the cause of embrittlement observed after heat-treatment, which limits the usage of the alloy for power plants. Mod. 9Cr-1Mo steel specimens at austenite temperature were quenched to the molten salt baths at $760^{\circ}C$ and $700^{\circ}C$, in which the specimens were kept for 10 min ~ 10 hr with subsequent air-cooling. Impact tests showed that the impact value dropped abruptly when the specimens were kept longer than 30 min at $\sim760^{\circ}C$ reaching to minima in about 1 hr, and then increasing at further retention. The tensile strength of the specimens reached the minimum value without much change afterward, whereas the values of elongation showed the same trend as that of the impact value. The isothermally heat-treated steel at $700^{\circ}C$ also showed a minimum impact value in about 1 hr. These results suggest that the isothermal heattreatment at 760 and $700^{\circ}C$ for about 1 hr induces temporal embrittlement in Mod. 9Cr-1Mo steel. The microstructural examination of all the specimens with extraction replica of the carbides revealed that the specimens with temporal embrittlement had $Cr_2C$, indicating that the cause of the embrittlement was the precipitation of the $Cr_2C$. In addition, TEM/EDX results showed that the Fe/Cr ratio was 0.033 to 0.055 for $Cr_2C$, whereas it was 0.48 to 0.75 for $Cr_{23}C_6$, making the distinction of the $Cr_2C$ and $Cr_{23}C_6$ possible even without direct electron diffraction analyses.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.404-409
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• 2006

Thin-film $ZnGa_2O_4 : Mn^{2+}$ phosphors of spinel structure were grown on quartz substrate by RF magnetron sputtering method at room temperature. As an increase of post-annealing temperatures, crystallinity, surface roughness and stoichiometry of thin films were varied. At the post-annealing temperatures of $500^{\circ}C$ and $600^{\circ}C$, the luminescence intensity was poor due to the poor crystallinity. The smallest surface roughness was observed at the sample post-annealed at $700^{\circ}C$ leading to low external extraction efficiency, and poor luminescence intensity. The highest luminescence intensity was shown at the sample post-annealed at $800^{\circ}C$. It was because both the surface roughness and crystallnity were optimized. On the other hand, at $900^{\circ}C$, the luminescence intensity was poor due to the violation of stoichiometry.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1077-1081
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• 2008

Soil and Water Assessment Tool(SWAT) 모형은 DEM(Digital Elevation Model)을 사용하여 지형인자를 추출하고 이를 바탕으로 수문 및 수질 모의가 이루어진다. 지형인자의 추출시 DEM 격자크기에 따라 상이한 결과를 초래할 수 있다. 그리하여 정확한 수문 및 수질 모델링에 있어 가능한 고해상도의 DEM을 사용하도록 권장하고 있다. 그러나 넓은 유역에서의 적용시 고해상도 DEM 사용에 따른 컴퓨터 처리 용량과 프로그램 실행 시 소요되는 시간상의 문제는 그 효율성에 있어서 문제시될 수 있다. 그리하여 본 연구에서는 소양강댐, 임하댐 유역을 대상으로 SWAT 모형에서 저해상도 DEM 사용으로 고해상도 DEM의 지형인자를 추출하여 자동 입력될 수 있는 모듈을 개발 적용하였다. 본 연구의 결과 소양강댐 유역을 대상으로 격자크기 20m DEM과 100m DEM을 사용하였을 때 연평균 유사량이 83.8%의 큰 차이가 발생한 반면 격자크기의 20m DEM과 본 모듈을 적용하여 20m DEM의 지형인자로 자동 보정된 100m DEM을 사용하였을 때의 연평균 유사량이 4.4%로 차이가 상당히 줄어든 것을 볼 수 있었다. 임하댐 유역의 경우는 격자크기 10m DEM과 100m DEM을 사용하였을 때 연평균 유사량이 43.4% 큰 차이가 발생하였다. 반면 격자크기 10m DEM과 본 모듈을 적용하여 10m DEM의 지형인자로 자동 보정된 100m DEM을 사용하였을 때의 연평균 유사량이 0.3%로 차이가 크게 줄어든 것을 확인 할 수 있었다. 또한 본 모듈의 검정을 위해 소양강댐 유역의 지형 자료와 유사한 충주댐 유역을 대상으로 본 모듈을 적용하여 검정을 실시하였다. 그 결과 연간 평균 유사량이 격자크기 20m와 100m의 DEM을 이용하였을 때 98.7%의 큰 차이가 발생한 반면 격자크기 20m와 본 모듈을 적용하여 보정된 경사도 값의 100m DEM을 사용하였을 때 20.7%로 차이가 크게 줄어든 것을 볼 수 있었다. 그리하여 본 연구의 결과를 통해 SWAT 모형에서의 개선된 지형인자 추출 방식을 사용하여 저해상도의 DEM 사용으로 고해상도 DEM 사용의 효과를 볼 수 있을 것이고 이로 인해 넓은 유역에서 저해상도 DEM 사용으로 컴퓨터 사용용량과 프로그램 지연 시간을 줄일 수 있을 것으로 판단된다. 향후 여러 유역을 대상으로 보정, 검정하여 보다 정확하고 통합적으로 적용될 수 있는 모듈의 개선이 필요할 것으로 사료된다.

• Journal of Sericultural and Entomological Science
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• v.51 no.2
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• pp.164-172
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• 2013

This study was carried out to investigate functional quality characteristics of extract obtained after sugar-leaching for 12 weeks (SLE) and extract obtained after lactic acid fermentation for 8 weeks (LFE) of mulberry leaves. The yield, sugar content, pH, and total acidity of SLE were 27%, 43 $^{\circ}Brix$, 4.6, and 0.45%. The yield, sugar content, pH, and total acidity of LFE were 166%, 33 $^{\circ}Brix$, 3.6, and 1.17% respectively. The lactic acid bacteria viable numbers ($1.2{\times}10^{10}$ CFU/ml) of LFE were more than those of SLE ($2.8{\times}10^2$ CFU/ml). The LFE expressed activities of hydrolytic enzymes (amylase, cellulase, pectinase, protease), but SLE did not express. The contents of acetic acid, citric acid, and malic acid of SLE were higher than those of LFE, but lactic acid content of LFE was higher than that of SLE. The main free sugars of SLE were glucose (200.93 mg/g), fructose (236.32 mg/g), and sucrose (18.41 mg/g), but LFE did not detect all free sugars. The contents of polyphenol, anthocyanin, and piperidine alkaloid of LFE were higher than those of SLE. ${\alpha}$-Glycosidase activities were inhibited 3.4% and 16.2% by SLE and LFE. These results suggest that lactic acid fermentation extraction is an effective method to increase the yield and contents of functional quality of mulberry leaves extract.

• Food Science and Preservation
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• v.12 no.5
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• pp.449-454
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• 2005

The objective of this study was to investigate the effect of drying methods on the physicochemical characteristics of Ponciri fructus. Immature fruits of Poncirus trifoliata were harvested, dried by shade, infrared, or freeze drying, and powdered to size of 20 mesh. Then, extracted for 3 hrs with hot-water or 40% ethanol(80$\circC$℃). Freeze dried powder showed significantly higher L and -a value. The content of hesperidin was not affected by drying methods. The yield was the highest from freeze drying. Water extracts showed significantly more browning color, and higher acidity and total sugar content than those of ethanol extracts. Acidity and total sugar of water extracts were the highest in infrared drying and freeze drying, respectively. Browning color, pH, acidity and total sugar of ethanol extracts were not affected by the drying methods. The results suggest that freeze drying has a beneficial effects to enhance the quality of Ponciri fructus.

• Food Science and Preservation
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• v.13 no.3
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• pp.351-356
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• 2006

This study was carried out to investigate the change of functional component and volatile flavor components from garlic for which both were treated with protopectinase (PPase) and mechanical maceration during storage period. Alliin content of gallic suspensions macerated mechanically were 11.0 mg/g at 0 day and 6.6 mg/g at 24 day. Whereas alliin content of garlic treated with PPase were 8.5 m/g at 0 day and 7.0 mg/g at 24 day. Importantly, over 40% of alliin which is the most unstable component during the mechanical maceration remained with an intact form for 24 day after the enzymatic treatment. The flavor component from gallic suspensions were extracted by solid-phase microextraction (SPME) and were analyzed and identified by gas chromatography (GC) and chromatography/mass spectrometry (GC/MS). The number and concentrations of flavor components of gallic macerated mechanically were increased during storage period, and total 18 kinds of flavor compounds were identified. Thus, the PPase treatment of garlic could be a better choice for preparation of the highly valuable and functional processed food as well as for prolonging the preservation period.

• Food Science and Preservation
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• v.23 no.2
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• pp.252-258
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• 2016

This study was conducted to investigate the antioxidant activities and physiological properties of Euphorbia humifusa extracts prepared using three different solvents (water, ethanol, and methanol). The highest total polyphenol content (293.25 mg/100 g) and total flavonoid content (21.05 mg/100 g) were observed in the methanol extract. The content of substances related to proanthocyanidin were highest in the water extract (8.42 mg/100 g), followed by methanol (5.70 mg/100 g) and ethanol (5.39 mg/100 g) extracts. The DPPH and ABTS radical scavenging activities of the methanol extract were 91.72% and 85.83%, respectively, at 50 mg% concentrations, which were higher than those of the other extracts. The extract reducing power decreased in the following order: ethanol > methanol > water. The methanol extract had relatively high antioxidant activity. The ${\alpha}-glucosidase$ and xanthine oxidase inhibitory activities of the methanol extract at a concentration of 10 mg% were somewhat higher than the other extracts. HMG-CoA reductase inhibitory activity in the water extract was slightly higher than in the methanol and water extracts. These results indicated that Euphorbia humifusa extracts were a high-value food ingredient due to their antioxidant activities and nutritional value.

• Food Science and Preservation
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• v.22 no.4
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• pp.591-597
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• 2015

In this study, extracts of chlorella using different extraction methods were compared for antioxidant activities and spray-dried chlorella powders were investigated for their physicochemical characteristics. The DPPH radical scavenging activity and superoxide radical scavenging activity of 50% ethanol extract were 29.19%, and 48.91%, respectively. The oxygen radical absorbance capacity (ORAC) of the 50% ethanol extract ($150.44{\mu}M/g$) was higher than those of other extracts. The total chlorophyll content of the 50% ethanol extract (542.89 mg/100 g) was higher than those of other extracts. The microencapsulation of the 50% ethanol extract was manufactured by spray-drying with 10 % maltodextrin (SD-C10), 20% maltodextrin (SD-C20), and 30% maltodextrin (SD-C30). The particle size of the freeze-dried powder ($454.47{\mu}m$) was higher than those of the spray-dried powders ($24.15{\sim}32.49{\mu}m$). Scanning electron microscope images showed that the spray-dried chlorella powders using SD-C10, SD-C20, and SD-C30 had an uniform particle distribution. The water absorption index and water solubility index (WSI) of powders were 0.31~0.45, and 96.96~98.28%, respectively. The spray-dried powders showed the stability in total chlorophyll content for 40 days storage. Based on these results, spray-dried chlorella powders could be used in various types of food processes.