• Journal of the Korean Society of Clothing and Textiles
• /
• v.47 no.1
• /
• pp.110-122
• /
• 2023

The COVID-19 pandemic increased people's time at home and caused an 80% increase in noise disputes between floors. The purpose of this study is to propose suitable materials for making indoor shoes (insoles) to minimize noise between floors. Subjects without back pain and leg-related disease (e.g. arthritis, etc.) from three different age groups (childhood, adolescence, and adulthood) were recruited for the study. Five polymer insole materials were considered: Chloroprene Rubber (CR foam), Ethylene Propylene Diene Monomer (EPDM foam), Natural Latex foam, Ethylene Vinyl Acetate (EVA foam), and Polyurethane (PU foam). From these materials, 20 combinations were prepared and randomly tested for noise and vibration. The results revealed a significant difference in noise and vibration levels based on the type of material used and the age of the subject. Nevertheless, all materials under consideration successfully reduced noise and vibration; in particular, type A-C greatly decreased. The CR foam material was especially effective at noise and vibration reduction (p<.01). This study suggests that adding insoles into socks that children wear at home could reduce noise vibration and disputes between floors.

• Journal of Microbiology and Biotechnology
• /
• v.8 no.5
• /
• pp.455-460
• /
• 1998

In the course of screening for new antitumor substances, a novel cytotoxic agent inducing apoptotic cell death was isolated from the culture broth of marine bacterial strain SCRC A-20. Strain SCRC A-20 was separated from a mollusk and was chemotaxonomically identified as a Streptomyces sp. The cytotoxic substance was purified by organic solvent extraction followed by silica gel column chromatography and preparative TLC. HRFAB-MS determined its molecular formula to be $C_{30}H_{40}N_2O_5$ (MW 508). The 1D and 2D NMR spectral data demonstrated that the substance has a novel lactam structure of a 20-membered macrocycle coupled with a unique acyl tetramine and bicyclo［3.3.0］ octane, which includes three methyl groups, six olefinic protons, five carbonyl groups, a conjugated diene and a dienone. The substance, named aburatubolactam C, appeared to be cytotoxic for various continuously proliferating tumor cells of human and murine origins. The $IC_{50}$ values determined by MIT assay were in the range of 0.3 to $5.8\mug/ml$. When Jurkat T cells were treated with $3\mug/ml$. of aburatubolactam C, the apoptotic DNA fragmentation was detectable within 3 h, indicating that the cytotoxic effect of aburatubolactam C on tumor cells is attributable to the induced apoptosis.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.11
• /
• pp.483-489
• /
• 2005

This study performs a simulation for an accumulation mechanism of contaminants, which were produced in an industrial belt of inland, on the surface of insulators. From the simulation, silicon insulators presented higher accumulation than that of EPDM(Ethylene Propylene Diene Terpolymer : EPDM) insulators on the same distance in the case of the Virgin polymer insulator, and this result presented the same result in the insulator applied in actual fields. In the case of the accumulation test for the Virgin insulator and insulators used in actual fields, it is evident that the Virgin insulator presented more accumulation than that of the insulator used in actual fields. The results can be caused by the generation of LMW (Low Molecular Weight) on the external material of polymer insulators, and the level of the accumulation can be changed according to the degree of the continuous generation of LMW. In order to simulate a certain pollution of an industrial belt, which is located along the coastline, leakage currents were measured by applying the contaminant compulsively that was produced with salts and Kaolin according to the ratio of its weight on the surface of insulators. The more increase in the content of Kaolin pollution, the level of leakage currents on the surface of polymer insulator more increased. In addition, the approaching time to the maximum value of leakage currents presented a nearly constant level regardless of the content of Kaolin. The level of leakage currents significantly decreased according to the passage of time, and the level of leakage currents on the surface maintained a constant level at a specific time regardless of the content of Kaolin.

• Journal of Food Hygiene and Safety
• /
• v.5 no.4
• /
• pp.237-242
• /
• 1990

This study was conducted to evaluate the usage of TBA method for the analysis of lipid peroxidation induced by streptozotocin. 5 mM streptozotocin and 1 % TBA alone showed the maximum peak at 309 nm and 358 nm respectively, although no peak was observed at 532 nm which was the wavelength to determine the absorbance for TBA method. When 5 mM streptozotocin was mixed together with 1 % TBA in vitro, new peaks at 439 nm and 532 nm had been detected, suggesting TBA did interact directly with streptozotocin forming new colored products. These results suggest that TBA method is not adequate for determination of lipid lperoxidation induced by streptozotocin.

• Journal of Nutrition and Health
• /
• v.37 no.9
• /
• pp.771-779
• /
• 2004

This study was performed to investigate the effect of dietary $\beta$-carotene supplementation on lipid metabolism and antioxidant enzyme activities in hyperlipidemic rats. Fifty Sprague-Dawley male rats aging 7 weeks were fed the control diet (CD,5% corn oil) and the high fat diet (HFD,15% beef tallow +1% cholesterol) for 4 weeks and then 0.02% $\beta$-carotene was supplemented to CD and HFD group for 8 more weeks. Serum lipid compositions, lipid peroxides and antioxidative enzymes in liver were analyzed at 4, 8 and 12week of the experiment. Serum levels of total lipid, total cholesterol, triglyceride, LDL-cholesterol, VLDL-cholesterol were higher in HFD groups than in CD groups (p < 0.001), Serum levels of HDL-cholesterol were higher in CD groups than in HFD groups (p < 0.01) . The effect of $\beta$-carotene supplementation was not significant in all groups but tended to be lower in total lipid, total cholesterol and Triglyceride. Thiobarbituric acid reactive substances (TBARS) levels in plasma and liver were showed significantly higher in HFD groups (p < 0.001, p < 0.05). The effects of $\beta$-carotene supplementation on the level of plasma and liver TBARS were not found except HFD groups at 12 week. Liver conjugated diene levels in HFD groups were higher than in CD groups (p < 0.01), but the effect of $\beta$-carotene supplementation did not show any differences. Liver lipofuscin levels were not significantly different among all groups. The activities of superoxide dismutase (SOD) and catalase were significantly lower in HFD groups at 8 week (p < 0.001) but were not significantly different at 4 and 12week. The activity of SOD in $\beta$-carotene supplemented HFD group was significantly higher at 8 week (p < 0.01). Glutathione peroxidase (GSH-Px) activity was significantly lower in HFD groups (p < 0.01) and was significantly increased in groups supplemented $\beta$-carotene (p < 0.05). It is suggested that $\beta$-carotene supplementation partly decreases the serum lipid and lipid peroxide levels and increases the activities of antioxidant enzymes in hyperlipidemic rats.

• Journal of Educational Research in Mathematics
• /
• v.23 no.2
• /
• pp.153-171
• /
• 2013

The purpose of this study is to investigate characteristics of students' problem solving processes based on their mathematical thinking styles and thus to provide implications for teachers regarding how to employ multiple representations. In order to analyze these characteristics, 202 university freshmen were recruited for a paper-and-pencil survey. The participants were divided into four groups on a mathematical-thinking-style basis. There were two students in each group with a total of eight students being interviewed. Results show that mathematical thinking styles are related to defining a mathematical concept, problem solving in relation to representation, and translating between mathematical representations. These results imply methods of utilizing multiple representations in learning and teaching mathematics by embodying Dienes' perceptual variability principle.

• Korean Journal of Food Science and Technology
• /
• v.26 no.6
• /
• pp.655-658
• /
• 1994

This study was designed to investigate the suitability of oxidation matters and physico-chemical characteristics as a quality evaluation for the extent of rancidity development in fats and oils undergoing thermal oxidation. The results showed that acid value rapidly increased during heating time. Soybean oil, especially revealed a faster increase than palm oil and palm olein. Anisidine value and conjugated diene value also increased. Especially, soybean oil increased more rapidly than palm oil and palm olein. Active oxygen method stability was good in the ranks of palm oil, palm olein and soybean oil. Primary oxidation matter (POM) and secondary oxidation matter (SOM) were surveyed as an evaluation method for the extent of rancidity development in fats and oils. POM and SOM showed a sharp increase during the thermal oxidation period.

• Journal of Nutrition and Health
• /
• v.36 no.9
• /
• pp.933-941
• /
• 2003

It has been suggested that green juice supplementation may have some health promoting benefits. We evaluated the effects of green juice (Angelica keiskei) consumption on parameters of lipid profiles and plasma antioxidant status in healthy male smokers. Fifty-four smokers were supplemented with 300 ml of green juice for 6 weeks while maintaining their normal diet. Blood samples were collected on week 0 and week 6 in order to evaluate plasma lipid profiles (total cholesterol, triglyceride, LDL-cholesterol, HDL-cholesterol) , plasma antioxidant vitamin levels (ascorbic acid, $\alpha$ -tocopherol, ${\gamma}$ -tocopherol, $\alpha$ -carotene, $\beta$ -carotene, cryptoxanthin and lycopene) , the degree of LDL oxidation and GOT, GPT levels for liver function. Plasma ascorbic acid level remained at the same level. However, $\alpha$ -tocopherol and ${\gamma}$ -tocopherol normalized by total cholesterol (p <0.05) and $\beta$ -carotene (p <0.001) level were all significantly increased after green juice supplementation. Plasma cholesterol was reduced for 12%, LDL-cholesterol was reduced for 9.3% after green juice consumption, while plasma triglyceride and HDL-cholesterol was not changed. Oxidized LDL assessed by conjugated diene (CD) , was decreased (p < 0.0001) after green juice consumption. These results further support a role for green juice supplementation in the improvement of lipid status, prevention of lipid peroxidation, and thereby reducing risk factors of numerous diseases associated with elevated oxidative stress in smokers.

• Journal of Nutrition and Health
• /
• v.43 no.5
• /
• pp.443-452
• /
• 2010

Elevated plasma concentration of total homocysteine (ptHcy) is known as an independent risk factor of cardiovascular disease (CVD) and oxidative stress is also commonly implicated in CVD. An association between ptHcy and oxidative stress has recently been suggested. The study objective is to examine the relationship between ptHcy and oxidative stress markers in 103 healthy college students (62 males and 41 females). Plasma levels of ptHcy, oxidative stress markers (conjugated diene, erythrocyte catalase, TRAP, lymphocyte DNA damage), antioxidant vitamins ($\alpha$-tocopherol, $\gamma$-tocopherol, carotenoids), and lipid parameters (total cholesterol, triglyceride, HDL cholesterol) were determined. The results show that the concentration of ptHcy was significantly higher in male subjects ($22.17\;{\pm}\;2.14\;{\mu}mole/L$) than in female subjects ($12.28\;{\pm}\;0.45\;{\mu}mole/L$). There was a negative association between ptHcy and plasma ${\beta}$-carotene in male subjects (p $lt; 0.05), but no correlation between ptHcy and other plasma antioxidant vitamin levels in either gender. However, there were the negative correlations between ptHcy and plasma ${\alpha}$-carotene or ${\beta}$-carotene, and a positive correlation between ptHcy and lymphocyte DNA damage. A significantly low level of ${\alpha}$-carotene or ${\beta}$-carotene was found in male subjects with elevated ptHcy (${\geq}\;15\;{\mu}mol/L$), as compared to those with lower plasma homocysteine. These study results confirmed the views on the association between plasma homocysteine and oxidative stress markers in humans and support the hypothesis that homocysteine promotes the oxidative environment by counteracting the antioxidant defense mechanism.

• Microbiology and Biotechnology Letters
• /
• v.2 no.3
• /
• pp.127-131
• /
• 1974

Inhibition of over-oxidation of prednisolone in the fermentation has been studied by using vegetative cells as enzyme source. firstly, A. simplex (ATCC 6946) was demonst.ated to degrade p.ednisolone in the vegetative culture of the microorganism. Over 72％ of hydrocortisone was transformed into prednisoloneby 3 hours of the fermentation. However, the prednisolone produced was considerably oxidized forming over-oxidation product in 8hours of fermentation period with the intact cells. Secondly, in order to depress the over-oxidation and the breakdown of the steroid skeleton of prednisolone, chelating agents such as $\alpha$$\alpha$'-dipyridyl, o-phenanthroline and 8-hydroxyruinoline were added to the fermentation broth. Conseauently, the breakdown of prednisolone by the iutact cells was able to be remarkably retatded and an intermediate regarded as an oxidized product derived from prednisolone was accumulated, by the addition of $\alpha$$\alpha$'-dipytidyl in the fermentation.