• Polymer(Korea)
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• v.28 no.3
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• pp.218-224
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• 2004

The adhesion and proliferation of mammalian cells on polymeric biomaterials depend on the surface characteristics such as wettability, chemistry, charge and roughness. In order to recognize the correlation between the adhesion and proliferation of human bone marrow derived stem cells (BMSCs) and surface property, radio frequency generated plasma treatment on low density polyethylene (LDPE) has been carried out. The modified LDPE surfaces were characterized by measuring the static water contact angle. The adhesion and proliferation of cells on LDPE films were characterized by cell counting and reverse transcription-polymerase chain reaction (RT-PCR). The water contact angle of the film surface decreased with plasma treatment time. Proto-oncogenes (c-myc, c-fos) and tumor suppressor gene (p153) showed maximum expression with contact angle of 60 ∼ 70$^{\circ}$ range of LDPE film. By cell counting, we confirmed that the rate of cell proliferation appeared the higher on the film surface of the contact angle of 60∼70$^{\circ}$ We concluded that the surface wettability is an important role for the growth and differentiation of BMSCs.

• Corrosion Science and Technology
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• v.18 no.5
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• pp.212-219
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• 2019

This paper reviews recent approaches to develop composite polymer-containing coatings by plasma electrolytic oxidation (PEO) using various low-molecular fractions of superdispersed polytetrafluoroethylene (SPTFE). The features of the unique approaches to form the composite polymer-containing coating on the surface of MA8 magnesium alloy were summarized. Improvement in the corrosion and tribological behavior of the polymer-containing coating can be attributed to the morphology and insulating properties of the surface layers and solid lubrication effect of the SPTFE particles. Such multifunctional coatings have high corrosion resistance ($R_p=3.0{\times}10^7{\Omega}cm^2$) and low friction coefficient (0.13) under dry wear conditions. The effect of dispersity and ${\xi}$-potential of the nanoscale materials ($ZrO_2$ and $SiO_2$) used as electrolyte components for the plasma electrolytic oxidation on the composition and properties of the coatings was investigated. Improvement in the protective properties of the coatings with the incorporated nanoparticles was explained by the greater thickness of the protective layer, relatively low porosity, and the presence of narrow non-through pores. The impedance modulus measured at low frequency for the zirconia-containing layer (${\mid}Z{\mid}_{f=0.01Hz}=1.8{\times}10^6{\Omega}{\cdot}cm^2$) was more than one order of magnitude higher than that of the PEO-coating formed in the nanoparticles-free electrolyte (${\mid}Z{\mid}_{f=0.01Hz}=5.4{\times}10^4{\Omega}{\cdot}cm^2$).

• Journal of the Korean Society of Physical Medicine
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• v.4 no.3
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• pp.141-148
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• 2009

Purpose：The purpose of this study was analyze the effect combination exercise program on plasma total antioxidant capacity and free oxygen radical according to exercise frequency of elderly. Age range of subject is 65~70 years. Methods：Subjects divided into three groups: control group(0-time), week-3 times group(3-times), week-5 times group(5-times). Each group were performed combination exercise during 8 weeks. Results：The results of each group by ANOVA free oxygen radical have a change(p<.05). We performed comparison of total antioxidant capacity and free oxygen radical pre-test and post-test on each groups. Total antioxidant capacity was increased in the 3-times and 5-times groups but there have not significant. Total antioxidant capacity is improve better than to 5-times. Free oxygen radical is significant increased in the 0-time (p<.05). But 5-times but 3-times is no significant decrease. Free oxygen radical is improve better than to 3-times. Conclusion：In the old people, exercise frequency week 3 times doing appeared effectively in improvement of the free oxygen radical and 5 times doing appeared effectively in improvement of the total antioxidant capacity. So rightly must apply a exercise frequency well in characteristic of old person each person.

• Journal of Nutrition and Health
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• v.34 no.8
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• pp.912-919
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• 2001

The increased oxidative stress may play an important role on the pathogenesis of diabetes and diabetic complications, and the blood level of vitamin C and lipid peroxidation in NIDDM patients may be used as an indicator for oxidative stress. However there is only scanty evidence on the blood level of vitamin C in NIDDM patients with or without diabetic complications. The study population consisted of 90 NIDDM patients(diabetes without complication, 48, and diabetes with complications, 42) and 41 normal subjects. The 42 diabetic complications were divided into 3 groups : 15 diabetic nephropathy, 18 diabetic neuropathy, 9 diabetic retinopathy. The anthropometric data and blood biochemical data were studied. The dietary intake was determined by 24 hour recall methods and food frequency questionnaire. The plasma concentrations of MDA and vitamin C were determined by fluorophotometer and HPLC respectively. 1) In blood lipoprotein study, diabetes with complication had higher level of TG than diabetes without complications, while no significant differences in total cholesterol, HDL, and LDL were shown. Diabetic neuropathy had the highest TG level among diabetic complication groups. 2) The intakes of vitamin B complexes(vitamin B$_2$, vitamin B$_{6}$, not vitamin B$_1$) and antioxidant vitamins(vitamin A and vitamin E, not vitamin C) and certain minerals such as iron and calcium in diabetes were not sufficient but the intakes of energy, protein, niacin, and phosphorus in diabetes were sufficient. The dietary intakes between diabetes with-and without complications were not significantly different. Among diabetic complications, the diabetic retinopathy had the lowest intake of vitamin B$_2$ and B$_{6}$(p < 0.05). the diabetic neuropathy or nephropathy consumed extremely low amount of vitamin A. 3) The MDA concentrations of NIDDM was significantly higher than that in controls(p < 0. 05) while no significant difference in the MDA concentration between with and without complications was shown. Although there were no statistical differences, the diabetic nephropathy and diabetic neuropathy showed the higher concentration of MDA than the diabetes without complications or diabetic retinopathy. 4) The plasma concentration of vitamin C in controls was higher than that in diabetes(p < 0.05) while the plasma vitamin C in diabetes with and without complications were similar. In diabetic complications, no differences in plasma vitamin C concentration of three groups were shown. This study showed that the oxidative stress in NIDDM patients was highly increased and the vitamin C reserve was significantly depleted, as compared with normals, although their intakes of vitamin C met korean RDA, which means that diabetes need more vitamin C intake to decrease oxidative stress in NIDDM patients.nts.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.8
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• pp.1193-1198
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• 2003

An increase in frequency of administration of exogenous growth hormone (GH) or GH-releasing hormone was reported to be a model to increase blood circulating insulin-like growth factor-1 (IGF-1) and to improve growth performance in animals. We have investigated the effect of twice daily administration of GH-releasing peptide-2 (GHRP-2) on growth performance, GH responsiveness and plasma insulin-like growth factor IGF-1 in swine. We administered to eight swine, 3 control and 5 treatment, a twice daily s.c. injections of GHRP-2 ($30{\mu}g/kg\;BW$) for a period of 10 days. Every day blood samples immediately taken before injections of GHRP-2 or saline, at 08:00 h and 16:00 h, were measured for IGF-1 concentrations. Blood samples for GH assay were collected every 20 min on days 1, 6 and 10, from 1 hour before and 3 h after GHRP-2 or saline injections at 08:00 h. GH peak concentrations and GH area under curve (GH AUC) on day 1, 6 and 10 in treatment group of swine were higher than those in control swine (p<0.05). Twice daily administration of GHRP-2 caused a significantly attenuation (p<0.05) of GH peak concentrations ($80.25{\pm}13.87$, $39.73{\pm}5.72$ and $27.57{\pm}6.06ng/ml$ for day 1, 6 and 10, respectively) and GH AUCs ($3,536.15{\pm}738.35$, $1,310.31{\pm}203.55$ and $934.37{\pm}208.99ng/ml$ for day 1, 6 and 10, respectively). However, there was no significant difference in GH peak concentration and GH AUC between day 6 and 10. Plasma IGF-1 concentration levels were higher in treatment than control group of swine (p<0.05) after 3 days of the treatment, and the levels reached a plateau from day 3 to 10 of experiment. Growth performance did not alter by GHRP-2 administration, even though a numerical increase of body weight gain and feed efficiency was observed. These results indicate that twice daily administration of GHRP-2 for 10 days in swine did not significantly influence on growth performance, caused an overall attenuation of GH response, and that elevation of plasma GH concentrations caused by GHRP-2 administration increased plasma IGF-1 concentrations, even though an attenuation of GH response was observed.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.1
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• pp.81-92
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• 1996

The Ar/Ar-$H_2$ plasma method was applied to reduce oxides and refine metals of V, Ta and B. In addition, the high temperature chemical reaction in Ar plasma and of the refining reaction in the Ar-(20%)$H_2$ plasma were analyzed. The crude V of 96wt% purity was obtained at the ratio of $C/V_{2}O_{5}=4.50$ by the Ar plasma reduction grade and the maximum reduction was obtained at $C/V_{2}O_{5}=4.50$ due to the $O_{2}$ loss from the thermal decomposition of vanadium oxide. In the Ar-(20%)$H_2$ plasma refining, the metallic V of 99.2wt% was produced at the ratio of $C/V_{2}O_{5}=4.40$. It was considered that a main refining reaction resulted from the chemical reaction between the residual carbon and residual oxygen. The metallic Ta of 99.8wt% was obtained at the ratio of $C/Ta_{2}O_{5}=5.10$ in a Ar plasma reduction and the Oz loss from the thermal decomposition of tantalum pentoxide did not take place. The deoxidation reaction was more significant than the decarburization reaction in the Ar-(20%)$H_2$ plasma refining and the metallic Ta of 99.9wt% was produced within the range of $C/Ta_{2}O_{5}$ ratio of 4.50 to 5.10. The Vickers hardness of Ta in the above mentioned range was about 220Hv due to the decrease in a residual oxygen by the deoxidation reaction. On the other hand, C is no suitable agent for the reduction of $B_{2}O_{3}$ by the Ar and Ar-$H_2$ plasma. But Fe-B-Si alloy was produced with the reduction of $B_{2}O_{3}$ in the melt when Fe, C, $B_{2}O_{3}$, and ferroboron mixtures were melted by the high frequency induction melting.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.36-44
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• 2010

The ambipolar diffusion equation has been solved in a fine-tube lamp of a few mm in diameter. In the diffusion of radial direction, the plasma diffuses and vanishes away at the glass wall by recombination with the characteristic time of plasma loss is given by $\tau_r\;=\;(r_0/2.4)^2/D_a$. With the radius $r_0{\sim}1\;mm$ and the ambipolar diffusion coefficient $D_a{\sim}0.01\;m^2/s$, the vanishing time is calculated $\tau_r{\sim}10\;{\mu}s$ which corresponds to the least value of frequency 30 kHz for the sustaining the plasma in the operation of high voltage AC-power. In the diffusion of longitudinal z-direction, a high density plasma generated at the area of a high voltage electrode, diffuses into the positive column with the characteristic time $\tau_z{\sim}0.1\;s$. The plasma diffusion velocity at the boundary of high density plasma is $u_D{\sim}10^2\;m/s$ at the time $t{\sim}10^{-6}$ s and the diffusion velocity becomes slow as $u_D{\sim}1\;m/s$ at $t{\sim}10^{-3}\;s$. Therefore, for the long lamp of 1 m, it takes about several seconds for the high density plasma at the area of electrode to diffuse through the whole positive column space.

• Journal of Nutrition and Health
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• v.38 no.10
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• pp.836-846
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• 2005

This study was performed to determine the effect of carotenoid-rich food consumption and smoking on the lipid peroxidation and antioxidant status in human. The subjects consisted of the health 210 middle-aged adults who visited health care center in the Inha University hospital. The blood and urine samples of the subjects were taken to analyze serum lipid profiles, plasma TBARS, total antioxidant status (TAS) and urinary 8-isoprostanes concentration. The anthropometric indices of the subjects were measured. The nutritional intake and the frequency of carotenoid-rich food consumption was determined by semi-quantitative food frequency questionnaire survey. HDL-cholesterol level of the smoking subjects was significantly lower than that of the non-smoking subjects in men. In the analysis of the carotenoid-rich food consumption, the frequency of pepper and tomato consumption of the non-smoking subjects was significantly higher than that of the smoking subjects in men. In women, the Sequency of pear and peach consumption of the non-smoking subjects was significantly higher than that of the smoking subjects. HDL-cholesterol level of the high carotenoid rich food consumption group was significantly higher than that of medium and low group in women. TAS of the high carotenoid rich food consumption group was significantly higher than that of medium and low group. In conclusion, carotenoid intakes seemed to be effective to reduce lipid peroxidation and increase antioxidant status in the body. The frequency of the carotenoid-rich food consumption seemed to be lower in the smokers than in the non-smokers. However, further researches consisted of large-scaled and randomized clinical trials are required to determine whether carotenoids have any other beneficial effect in human. (Korean J Nutrition 38(10): 836$\sim$846,2005)

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.329-337
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• 1989

Cardiac muscles show stimulation frequency-dependent tension changes i.e. Bowditch phenomenon and Woodworth phenomenon, the former is an increase of tension with the increase of stimulation frequency, whereas the latter is an increase of tension with a decrease of stimulation frequency. Bowditch phenomenon is seen in the range of frequency 1.0 cps and above, and Woodworth phenomenon below the frequency 1.0 cps in the most of mammalian cardiac atrium. To throw some light on the possible mechanism of both phenomena in rat atrium, influences of drugs affecting $Ca^{2+}$ influx through the plasma membrane $(verapamil,\;La^{3+},\;norepinephrine)$ and $Ca^{2+}$ release from sarcoplasmic reticulum (SR) on frequency-tension curve were studied. The results obtained are summarized as follows: 1) At low temperature $(27.5^{\circ}C)$, both Bowditch and Woodworth phenomenon were demonstrated. But Bowditch phenomenon disappeared at the temperature above $(32.5^{\circ}C)$. 2) At $(27.5^{\circ}C)$, in the presence of verapamil, a $Ca^{2+}$ channel blocker, a time course of change in the frequency-tension was studied. It was found that Bowditch phenomenon was affected before the Woodworth phenomenon, then the former was completely disappeared. At $(32.5^{\circ}C)$, where no Bow-ditch is seen in normal atrial muscle, Bowditch phenomenon was reappeared by an administration of norepinephrine suggesting again that slow inward current of such as $Ca^{2+}$ channel is closely related to Bowditch phenomenon. 3) At $27.5^{\circ}C$, in the presence of $La^{3+}$, although tensions were decreased at all stimulation frequencies, Bowditch and Woodworth phenomenon were still demonstrated. However in the presence of both $La^{3+}$ and verapamil, Bowditch phenomena was disappeared suggesting that $La^{3+}$ is less effective in blocking $Ca^{2+}$ channel than verapamil. 4) At $27.5^{\circ}C$, in the presence of ryanodine, an inhibitor of calcium release from SR, Woodworth phenomenon was disappeared, which was consistent with previous reports of others, suggesting that $Ca^{2+}$ release from SR is closely related to Woodworth phenomenon. From the above findings, it may be concluded that Bowditch phenomenon is dependent on the magnitude of $Ca^{2+}$ influx through slow channel and Woodworth phenomenon is dependent on the amount of $Ca^{2+}$ stored in SR.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.11
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• pp.1043-1048
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• 1998

The decomposition performance of the Surface induced Plasma Chemical Processing(SPCP) for benzene, toluene, xylene and $NO_2$ were experimentally examined. Discharge exciting frequency range was 5kHz and 10kHz, and low frequency discharge requires high voltage to inject high electric power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power in gas and to decompose contaminants. The decomposition rate of dioxide nitrogen for 5kHz power supply is only 85%, but it’s rate for 10kHz power supply is very high, more than 96% when peak voltage is 12kv. Aromatic hydrocarbon vapor of up to 1000ppm is almost throughly decomposed at the flow rate of 1000$\ell$/min or lower rate under the discharge with electric power of several hundred watts. High decomposition rate is shown in every case, that is, for SPCP reactor is necessary to obtain the decomposition rate of more than 80~98%. The decomposition rate of benzene, toluene and xylene were 90~98% and dioxide nitrogen was 45~96%.