• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.131-137
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• 1986

Cutting oil cools the chip and a tool as well as lubricates the chip-tool interface, the flank and machined surface. Rehbinder effect has been known as a phenomenon, the reduction of mechanical strength, when the metal is exposed to a polar organic environment or the surface of metal is coated with some polar organic substances. About the cause of Rehbinder effect there have been many different ideas by Rehbinder, Shaw, Barlow, Sakida and etc. In this report, the efect of polar organic substance( $C_{6}$ $H_{5}$C $H_{3}$+ $C_{6}$ $H_{4}$(C $H_{3}$)$_{2}$+ $C_{4}$ $H_{9}$OH+ $C_{6}$ $H_{12}$ $O_{2}$) (magic ink) upon the mechanism of chip formation on the orthogonal cutting of copper and mechanical properties of the work material are experimentally discussed with various rake angles. As expected no lubrication action could be noticed, but the shear angle increased and the cutting force and shear strain on the shear plane decreased, therefore the work material must be embrittled under polar organic substance.substance.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.83-85
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• 2019

Pseudomonas sp. PAMC 29040 was isolated from a maritime tundra soil in Antarctica for its ability to degrade lignin and subsequently confirmed to be able to depolymerize heterogeneous humic substance (HS), a main component of soil organic matter. The draft genome sequences of PAMC 29040 were analyzed to discover the putative genes for depolymerization of polymeric HS (e.g., dye-decolorizing peroxidase) and catabolic degradation of HS-derived small aromatics (e.g., vanillate O-demethylase). The information on degradative genes will be used to finally propose the HS degradation pathway(s) of soil bacteria inhabiting cold environments.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.712-720
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• 2022

In this study, we evaluated the production and photoreactivity of CDOM of two polar phytoplanktons - Phaeocystis antarctica and Phaeocystis pouchetii, in order to find out UV effects on phytoplanktons. In visible region, CDOM in media of both phytoplanktons under UV-R decreased during 48hrs incubation period. However, in UV region CDOM decreased 30 % in the media of P. antarctica, but increased 10% in media of P. pouchetii, compared to CDOM concentrations of control after 48 hr incubation. This result indicates that biota in polar environment would not well protected from UV-R harmful effect when P. antarctica is dominant because of loss of CDOM, but when P. pouchetii is dominant species, production of UV absorbing organic matter could play more efficiently for UV screening for marine biota. Also we confirmed that FDOM of humic substance (C-peak) produced by these phtoplanktons under UV-R stress were well matched with fluorescence characteristics of the UV-protecting compound, MAAs. This finding shows that Phaeocystis pouchetti with low photoreactivity would contribute to DOM pool of polar marine environment under stratification by global warming.

• Journal of Pharmacopuncture
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• v.21 no.2
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• pp.48-60
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• 2018

Objective: The aim of this study is to optimize the extraction of beneficial substance from Cudrania tricuspidata leaves grown at Jirisan Mountain in South Korea by three different solvents depending on extraction time and at different temperature. Methods: The total phenolic contents were determined by the method reported by $S{\acute{a}}nchez$-Moreno et al. The total flavonoid contents were analyzed by Slinkard and Singleton. The DPPH radical scavenging activity was determined according to the method reported by Blois Results: The extraction yield for each solvent is 9.05-14.1%, 2.17-5.67%, and 2.3-3.9% for D.W., ethanol, and hexane, respectively. The overall results were maximized for the extract obtained with D.W. for 5 min at $100^{\circ}C$. The average phenol contents were 77.11, 45.64, and 0.343 mg/g at $100^{\circ}C$ in water, $78^{\circ}C$ in ethanol, and $68^{\circ}C$ in hexane, respectively. The flavonoid contents were the highest in the materials extracted with D.W., and were increased with increasing temperature, regardless of the extraction solvents, whether water (green), polar organic ethanol, or nonpolar organic hexane. In the ethanol extract, the flavonoid contents are increased gradually from 5.66 mg/g to 7.73 mg/g. The total flavonoid contents were proportional to the concentrations of the water extracts, ranging from 4.14 mg/g to 48.89 mg/g. The antioxidative activities of the water-extracted compounds are generally increased with increasing temperature from 42.5% to 85.5%. Those of the hexane extracts are increased slowly from 3.79% to 8.8%, while those of ethanol extracts are increased from 29.8% to 47.4%. Conclusion: The extraction yields were dependent upon solvents for extraction as well as extraction time and the temperature. The optimal extraction time was 5 min and the extraction yields were increased with increasing temperature excepted hexane. Of the three tested extraction solvents, the greenest solvent of water shows excellent results, suggesting that water is among the most effective solvents for natural sample extractions for general medicinal, pharmaceutical, and food applications.

• Preventive Nutrition and Food Science
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• v.6 no.2
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• pp.133-135
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• 2001

The edible part of cucurbita moschata Duch, which is commonly used as a Korean traditional medicine as well as a popular food source, was studied to isolate anti-complementary substance. Extracts of Cucurbita moschata Duch showed significant anti-complementary activities on the classical pathway of the complement system. Especially, the ripe Cucurbita moschata Duch had more activity than that of the complement system. Especially, the ripe Cucurbita moschata Duch had more activity than that of the green one in terms of the overall anti-complementary activity. Among the extracts of various organic solvents of the ripe Cucurbita moschata Duch, chloroform and ethyl-acetate extracts, which are non-polar solvent extracts, showed the strongest activities. These results suggest that the major difference in the solvent extraction for the anti-complementary substances depends on the change in the chemical composition such as the fatty acid with the degree of ripening.

• Ocean and Polar Research
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• v.29 no.2
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• pp.87-99
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• 2007

This study was conducted to understand the source and behavior of organic matter using the fluorescent technique (excitation-emission matrix) as a part of environmental monitoring program in the Korea manganese nodule mining site in the Northeastern Pacific Ocean. Water samples were collected at $0^{\circ},\;6^{\circ}N$, and $10.5^{\circ}N$ along $131.5^{\circ}W$ in August 2005. The concentration of total organic carbon (TOC) ranged from 58.01 to $171.93\;{\mu}M-C$. The vertical distribution of TOC was characterized as higher in the surface layer and decreased with depth. At $6^{\circ}N$, depth-integrated (from surface to 200 m depth) TOC was $337.1\;gC/m^2$, which was 1.4 times higher value than other stations. The exponential decay curve fit of vertical profile of TOC indicated that 59% of organic carbon produced by primary production in the surface layer could be decomposed by bacteria in the water column. Dissolved organic matter is generally classified into two distinctive groups based on their fluorescence characteristics using three-dimensional excitation/emission (Ex/Em) fluorescence mapping technique. One is known as biomacromolecule (BM; protein-like substance; showing max. at Ex 280/Em 330), mainly originated from biological metabolism. The other is geomacromolecule (GM; humic-like substance; showing max. at Ex 330/Em 430), mainly originated from microbial degradation processes. The concentration of BM and GM was from 0.42 to 7.29 TU (tryptophan unit) and from 0.06 to 1.81 QSU (quinine sulfate unit), respectively. The vertical distribution of BM was similar to that of TOC as high in the surface and decreased with depth. However, the vertical distribution of GM showed the reverse pattern of that of BM. From these results, it appeared that BM occupied a major part of TOC and was rapidly consumed by bacteria in the surface layer. GM was mainly transformed from BM by microbial processes and was a dominant component of TOC in the deep-sea layer.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.274-278
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• 2008

Ethanol extracts from the edible mushroom hinmogi (Tremella fuciformis, TF) were used in the investigation of effects on $\alpha$-glucosidase in vitro and on glucose-uptake in 3T3-L1 mature adipocytes. Addition of the extract significantly inhibited $\alpha$-glucosidase from small intestine of porcine and of rat (about 42 and 35% of control, respectively), and stimulated glucose uptake (about 100% of control), of which activity was higher than that of maitake (Grifola frondosa) X-fraction, a well known anti-diabetic substance. When the ethanol extracts were further partitioned successively by organic solvents and purified by silica gel chromatography, the non-polar layer (F-7) from hexane layer showed highest stimulatory activity of glucose-uptake among layers tested. The major components of the F-7 were 1-monooleoylglycerol and 1-monopalmitoylglycerol. Our report is the first description of TF with stimulatory activity of glucose-uptake. These results suggest that TF extracts may constitute a new source of glucose transport activator and could be employed as a potential anti-diabetic material for treatment and preventing diabetes.