• Elastomers and Composites
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• 제51권1호
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• pp.1-9
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• 2016

Characterization of the UV oxidation for raw natural rubber (NR) was investigated in controlled conditions through image and FT-IR analysis. The UV oxidation was performed on a thin film of natural rubber coated on a KBr window at 254 nm and room temperature to exclude the thermal oxidation. Before or after exposure to UV light, image of the NR thin film was observed at a right or tilted angle. FT-IR absorption spectra were measured in transmission mode with the UV irradiation time. The UV oxidation of NR was examined by the changes of absorption peaks at 3425, 1717, 1084, 1477, 1377, and $833cm^{-1}$ which were assigned to hydroxyl group (-OH), carbonyl group (-C=O), carbon-oxygen bond (-C-O), methylene group $(-CH_2-)$, methyl group $(-CH_3)$, and cis-methine group $(cis-CCH_3=CH-)$, respectively. During the initial exposure period, the results indicated that the appearance of carbonyl group was directly related to the reduction of cis-methine group containing carbon-carbon double bond (-C=C-). Most of aldehydes or ketones from carbon-carbon double bonds were formed very fast by chain scission. A lot of long wide cracks with one orientation at regular intervals which resulted in consecutive chain scission were observed by image analysis. During all exposure periods, on the other hand, it was considered that the continuous increment of hydroxyl and carbonyl group was closely related to the decrement of methylene and methyl group in the allylic position. Therefore, two possible mechanisms for the UV oxidation of NR were suggested.

• 한국직업건강간호학회지
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• 제17권1호
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• pp.86-95
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• 2008

Purpose: The objectives for this study are to produce the comprehensive management indexes and find their application strategies for appropriate medical care in primary care clinics under workers' compensation insurance. Method: Data of this study was workers' compensation insurance medical fees claim's data from July 2006 to June 2007. Data were analyzed using SAS 9.1 version by applying descriptive statistics and Pearson's correlation. The indexes such as costliness index(CI), standard medical fee were calculated based on the fourth revision of korean classification of diseases(KCD-4.). Results: The CI, visiting index(VI), outliers index(OI), and medical review adjustment percentage were positively correlated in the both inpatient and outpatient medical fees in primary care clinics under workers' compensation insurance. The major medical specialities were neurological surgery, general medicine, general surgery, rehabitational medicine, and orthopedic surgery. The CIs were slightly high in rehabitational medicine among major medical specialities. The CIs were mostly high in diagnosis, test, anesthesia, and rehabitational assistive device fees among major medical specialities. The CIs were slightly high in Kwangju, Daegu, Daejeon, and Busan districts among district management centers of Korea Workers' Compensation and Welfare Service. Conclusions: We suggest the continuous development of appropriate disease classification system and medical care quality indicators to successfully take root the comprehensive management for appropriate medical care under workers' compensation.

• Journal of Biosystems Engineering
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• 제32권4호
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• pp.215-222
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• 2007

In the study, the cone index, the cohesion and the internal friction angle of soil were measured before and after tillage in order to suggest relative improvement in soil properties by comparing the two measured values before and after tillage. The tillage methods tested in the study were five combinations of plowing and rotovating; one plow tillage operation, one plow followed by one rotary, one plow followed by two rotary, one rotary without plow and two rotary without plow. The experiments were performed in a soil bin in Sunggyunkwan Univ. and in four selected test fields in Yeoju, Seodun-Dong, Suwon (especially, two different fields) and Chungju. In general, the internal friction angle and cohesion of soil increased with the increase of soil compaction. After applying the tillage operations, the internal friction angle reduced by 14 degree and the cohesion decreased up to about $2.2N/cm^2$ on the soil bin in comparison with those before tillage. The two values, however, reduced by 9 degree and up to about $1.0N/cm^2$ on the tested fields. The CIs for all the tillage operations on the soil bin and on 4 different test fields were decreased by 800 kPa in comparison with those before tillage. The best combination of tillage operations for decreasing the CIs of soil was one plow operation followed by one rotary. The CIs for one plow operation followed by two rotary were slightly higher than that for one plow operation followed by one rotary because one plow operation followed by two rotary crushed down the soil excessively, so that the porosity of soil decreased.

• 대한조선학회논문집
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• 제60권1호
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• pp.1-9
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• 2023

In order to improve the propeller cavitation performance composed of Cavitation Inception Speed (CIS), cavitation extent and pressure fluctuation, it needs to improve the wake distribution that flows into the propeller. The warship propeller cavitation is strongly influenced by the wake created at the V-strut of various appendages. The inflow characteristics of the V-strut were investigated using Computational Fluid Dynamics (CFD) and the twisted angles of the V-strut were aligned with upstream flow. The resistance and self-propulsion tests for the model ship with the existing and modified V-struts were conducted in Towing Tank (TT), and wake distribution, CIS, cavitation observation and pressure fluctuation tests were conducted in Large Cavitation Tunnel (LCT). The propeller behind the modified V-strut showed better cavitation characteristics than that behind the existing V-strut. Another model test was conducted to investigate rudder cavitation performance by the change of the V-strut. The rudder cavitation characteristics were not improved by the change of the operating conditions. On the basis of the present study, it is thought that the stern appendages for better propeller cavitation performance would be developed.

• Natural Product Sciences
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• 제20권2호
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• pp.86-90
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• 2014

Phytochemical investigation of the 80% MeOH extract from the leaves of Hosta longipes resulted in the isolation of sixteen compounds (1 - 16). The structures of the compounds were elucidated by spectroscopic methods to be methyl 10,10-dimethoxydecanoate (1), methyl 10-hydroxy-8E,12Z-octadecadienoate (2), methyl coriolate (3), trans-phytol (4), phytene-1,2-diol (5), phyton (6), (3S,5R,6S,7E,9R)-7-megastigmene-3,6,9-triol (7), (3S,5R,6S,9R)-3,6,9-trihydroxymegastigman-7-ene (8), shikimic acid (9), p-coumaramide (10), trans-N-p-coumaroyltyramine (11), cis-N-coumaroyltyramine (12), tryptophan (13), thymidine (14), adenosine (15), and deoxyadenosine (16). Compound 1 was synthesized, but not yet isolated from natural source, and compounds 2-16 were isolated for the first time from this plant source.

• Archives of Pharmacal Research
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• 제28권5호
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• pp.534-540
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• 2005

Activity-guided fractionation of the CH$_2Cl_2$-soluble fraction of the roots of Sophora flavescens furnished five 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scaveng ers: trans-hexadecyl ferulic acid (1) cis-octadecyl ferulic acid (2), trans-hexadecyl sinapic acid (3), (-)-4-hydroxy-3-methoxy-(6aR,11aR)-8, 9-methylenedioxypterocarpan (4) and desmethylanhydroicaritin (8), along with nine known inactive compounds: (-)-maackiain (5), xanthohumol (6), formononetin (7), (2S)-2'-methoxykurarinone (9), (2S)-3${\beta}$,7,4'-trihydroxy-5-methoxy-8-(${\gamma},{\gamma}$- imethylallyl )-flavanone (10), (2S)-7,4'-dihydroxy-5-methoxy-8- (${\gamma},{\gamma}$-dimethylallyl ) -flavanone (11), umbelliferone (12), kuraridin (13), and trifolirhizin (14). Compounds 1-4 and 8 exhibited DPPH free radical scavenging effects at IC$_{50}$ values of 33.01 ${\pm}$ 0.20, 57.06 ${\pm}$ 0.16, 39.84 ${\pm}$ 0.36, 35.83 ${\pm}$ 0.47, and 18.11 ${\pm}$ 0.04${\mu}$M, respectively. L-Ascorbic acid, when used as a positive control, exhibited an IC$_{50}$ value of 7.39 ${\pm}$ 0.01 ${\mu}$M. Compounds 1-4 and 8 also appeared to exert significant scavenging effects on authentic ONOO-, with IC$_{50}$ values of 5.76 ${\pm}$ 1.19, 15.06 ${\pm}$ 1.64, 8.17 ${\pm}$ 4.97, 1.95 ${\pm}$ 0.29 and 4.06 ${\pm}$ 2.41 ${\mu}$M, respectively. Penicillamine (IC$_{50}$= 2.36 ${\pm}$ 0.79${\mu}$M) was used as a positive control. In addition, compounds 2,4,6,8, and 10 were isolated from this plant for the first time.

• 한국식품과학회지
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• 제31권6호
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• pp.1453-1457
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• 1999

항산화 및 항암 작용이 있는 것으로 알려진 conjugated linoleic acid(CLA)를 식물성 유지로부터 알칼리 이성질화에 의해 고 농도의 CLA 농축물을 얻기 위한 최적 조건을 연구하였다. 지방산 조성이 상이한 식물성 유지를 알칼리 이성질화 하였을 때 CLA 생성량은 유지중 linoleic acid 함량이 많은 것이 가장 높았다. 홍화유를 알칼리 이성질화할 때 KOH 농도는 $8{\sim}11%$, 가열온도는 $180{\sim]185^{\circ}C$에서 cis-9, trans-11 CLA와 총 CLA 생성량이 가장 높았고, 가열시간은 CLA 생성량에 큰 영향을 미치지는 않았으나 $20{\sim}40$분이 가장 적당하였다. 홍화유를 silicic acid column chromatograph)에 의해 중성, 당 및 인지방질의 lipid class를 분획하여 알칼리 이성질화를 시켰을 때 중성지방질의 획분에 CLA가 가장 많이 함유되었다. 알칼리 이성질화시킨 홍화유를 요소처리와 HPLC 분획에 의해 95.4%의 CLA 농축물을 얻을 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권9호
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• pp.1363-1372
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• 2019

Objective: This study was designed to investigate the effect of diet supplementation with rubber seed oil and flaxseed oil on serum fatty acids profile, oxidation stability of serum and milk, and immune function of dairy cows. Methods: Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of four treatments for 8 wk, including basal diet (CON) or the basal diet supplemented with 4% rubber seed oil (RO), 4% flaxseed oil (FO) or 2% rubber seed oil plus 2% flaxseed oil (RFO) on a dry matter basis. Results: Compared with CON, all the oil groups increased the levels of trans-11 C18:1 (vaccenic acid), cis-9, trans-11 C18:2 (conjugated linoleic acid, CLA) and C18:3 (${\alpha}$-linolenic acid, ALA) in serum. Both the activity of glutathione peroxidase and catalase in serum and milk in oil groups were decreased, which were negatively correlated with the levels of cis-9, trans-11 CLA and ALA. The concentrations of proinflammatory factors (tumor necrosis factor ${\alpha}$ and interferon ${\gamma}$) in serum of oil groups were lower than that from the CON cows. Conclusion: These results indicate that diet supplementation with RO or FO could alter serum fatty acid profile and enhance the immune function of dairy cows. However, the negative effect on milk oxidation stability should be considered when feeding these n-3 polyunsaturated fatty acid-enriched oils in dairy production.

• Asian-Australasian Journal of Animal Sciences
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• 제16권2호
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• pp.222-226
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• 2003

The effects of dietary sources of C18:2 n-6 or C18:3 n-3 fatty acids on the occurrence of conjugated linoleic acid (CLA) and time-dependent changes of free fatty acid fractions in rumen contents were investigated. Sheep (n=4) fitted with rumen fistula were used in a 44 Latin square design wxith each 14 d period. Sheep were fed one of four diets consisting of grass hay and concentrates in a ratio of 70:30. Dietary treatments were 100% concentrates (served as the control), and concentrates were replaced by safflower seed at 30% (SFS), safflower meal at 18% - safflower oil at 12% (SFO), and safflower meal at 18%-linseed oil at 12% (LNO). At the end of each experimental period, rumen contents from each sheep were collected before feeding and at 1, 3, 6 and 12 h after feeding. The levels of cis-9, trans-11 CLA in free fatty acid fraction were considerably increased in all treated groups relative to the control, but not significantly. The increase in cis-9, trans-11 CLA was slightly higher in SFS and SFO groups than group fed diet containing linseed oil. The level of cis-9, trans-11 CLA in free fatty acid fraction was reached to the maximum value at 1hr after feeding and, thereafter gradually decreased to near the value before feeding. The generation of trans-11 C18:1 was significantly higher in all treated groups than that of control. The level of trans-11 C18:1 was linearly increased after feeding of experimental diets, reaching the maximum value at 3 h. Feeding of diets containing polyunsaturated fats to sheep resulted in a marked increase in the levels of trans-11 C18:1 and a slight increase of CLA in free fatty acid fraction of rumen contents. Our results support that endogenous synthesis of CLA from trans-11 C18:1 may be involved the primary source of CLA in dairy product. (Asian-Aust.

• Toxicological Research
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• 제8권2호
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• pp.217-233
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• 1992

This study was performed to determine the toxic effects of graded dose levels of SKI 2053R after repeated administration. Three groups of Sprague-Dawley rats(10M and 10F per group) were given a total of 25 i.v. injections of SKI 2053R (1.50,3.75,9.38mg/kg/day). In order to compare the toxic effects of SKI 2053R with those of cisplatin, one group of Sprague-Dawley rats (10M and 10F per group) were given a total of 25 i.v.injections of cisplatin (1.70mg/kg/day). The dosing schedule was divided into five courses of 5 consecutive days with 16-day dose-free intervals between each course. No drug-related toxicity occurred in low dose level group (1.50mg/kg/day) of SKI2053R. From the results of hematological examination, peripheral WBC counts, RBC counts and hemoglobin of high dose level group(9.38mg/kg/day)of SKI 2053R were significantly lower than those of no-treated group. Other toxicities including reduced final body weight, proteinuria and hematuria were observed in high dose level group of SKI 2053R. But, no change was detected in serum biochemical values of SKI 2053R treated groups. All of the rats in cisplatin treated group were died between 3 and 13 weeks, while rats treated with SKI2053R survived to the end except one rat of middle dose level group(3.75mg/kg/day). In histopathological examinations, rats that received cisplatin manifested severe tubular damage in kidney and hemosiderosis in spleen, but no critical pathological lesion was observed in rats of other groups. Considering the results of this study, it was concluded that non-toxic dose of SKI 2053R in this treatment schedule was estimated to be 3.75 mg/kg/day and the maximum tolerated dose was to be higher than 9.38mg/kg/day. The toxic profiles fo SKI 2053R were different from those of cisplatin, and its toxicity was considerably lower than that of cisplatin.