• Journal of Preventive Medicine and Public Health
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• v.25 no.3 s.39
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• pp.312-329
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• 1992

The purpose of this study is to estimate cesarean section rate in Korea and analyze the socioeconomic variables and health resources which affect regional variation in the rate. Samples were drawn from the record of vaginal and cesarean section deliveries based upon insurance claim bills which have been submitted to the National Federation of Medical Insurance for the first three months, January through March, 1991. The results are obtained as follows : It was found that. cesarean section rate was increasing rapidly up to 23.1% in 1991. Cesarean section per 10 thousand insured people was 4.8 and the number of cesarean section per 10 thousand insured eligible($15{\sim}49$ years old) female was 7.6. The fee for normal delivery was 109,489 won and that for cesarean section was 390,024 won. The average days of hospitalization in normal delivery was 2.3 days, and those in cesarean section was 7.6 days. On the average cesarean section has a longer of stay as much as by 4.3 days and cost 3.6 times more than normal deliveries. Cesarean section rates vary among medical facilities 19.8% at clinics 37.6% in small-scale hospitals, and 29.1% in general hospitals. The regional variation of cesarean section rates was also fairly prominent. The South Cheju Gun has the highest rate of cesarean section, 56.2%. Meanwhile no cesarean section cases has been reported in Sunchang Gun during the period of this study. The variation is noted among provinces. The rate for Cheju province has been 3.4 times higher than that for Chunnam. The number of cesarean section per 10 thousand insured people vary greatly among regions, too. This study has found that there exists significant regional variations among various geographic units in terms of average length of stay, average cost, number of obsretricians and number of beds. Multiple regression analysis was done to identify factors explaining the regional variance of various cesarean section rates : In the urban areas, no significant explaining variables were noted except the number of beds for the dependent variable of cesarean section cases per 10 thousand insured eligible females. The smaller the number of bed, the more cases of cesarean section was noted for an urban area. The is mostly because the rate of cesarean section is higher in medium-size hospitals than in large general hospitals. In the rural areas, the factor of education has been found significant for all three deplendent variables. The higher the educational level, the rate of cesarean section is most likely to rise. An income variable measured by the amount of monthly insurance contribution has been identified a powerful predictor in explaining the valiance of cesarean section rates. The same has been noted for the number of obstetricians. Similar findings are observed for the country as a whole. The income level has veen found as the most powerful explaining factor in the regional variance of cesarean section rates. In general the rate is higher in the urban areas, and lower in the area with more small hospitals. As this is the initial attempt to identify the factors relevant to the regional difference in the rates of cesarean section, more elaborated study is urgently required.

• Animal cells and systems
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• v.1 no.3
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• pp.467-473
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• 1997

Taurine (2-aminoethanesulfonic acid), one of bioactive amino acid in the mammalian brain, is known to exert inhibitory effects on neurons via GABA receptor. In the present study, we examined effects of taurine on glutamateinduced neurotoxicity on hippocampal neuron cell culture using cell counting method and lactate dehydrogenase (LDH) assay. After 10 d of culture, cells were stimulated with appropriate drugs. Only 43% of cultured neuronal cells survived at one day after stimulation with 500 uM L-glutamate for 10 min. Survival rate was enhanced by 82% in the presence of 10 mM taurine. LDH activity from the culture supernatant incubated with a combination of L-glutamate and taurine was less than half of that with L-glutamate alone. In the next series of experiments, interleukin-6 (IL-6) mRNA expression in cultured astrocytes was investigated using reverse tanscription-PCR (RT-PCR). IL-6 mRNA was detected in the astrocytes stimulated with L-glutamate in a dose-dependent manner, while not detected in the unstimulated control astrocytes. The expression of IL-6 mRNA caused by 10 mM glutamate was inhibited by taurine, but not by GABA. These findings demonstrated a neuroprotective action of taurine against glutamate-induced toxicity.

• Journal of Microbiology
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• v.42 no.4
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• pp.346-352
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• 2004

Poly(3-Hydroxybutyrate-co­3-Hydroxyvalerate), poly(3HB-co-3HV), copolyesters with a variety of 3HV contents (ranging from 17 to $60\;mol\%$) were produced by Alcaligenes sp. MT-16 grown on a medium containing glucose and levulinic acid in various ratios, and the effects of hydrophilicity and crystallinity on the degradability of the copolyesters were evaluated. Measurements of thermo-mechanical pro­perties and Fourier-transform infrared spectroscopy in the attenuated total reflectance revealed that the hydrophilicity and crystallinity of poly(3HB-co-3HV) copolyesters decreased as 3HV content in the copolyester increased. When the prepared copolyester film samples were non-enzymatically hydrolysed in 0.01 N NaOH solution, the weights of all samples were found to have undergone no changes over a period of 20 weeks. In contrast, the copolyester film samples were degraded by the action of extra­cellular polyhydroxybutyrate depolymerase from Emericellopsis minima W2. The overall rate of weight loss was higher in the films containing higher amounts of 3HV, suggesting that the enzymatic degra­dation of the copolyester is more dependent on the crystallinity of the copolyester than on its hydro­philicity. Our results suggest that the degradability characteristics of poly(3HB-co-3HV) copolyesters, as well as their thermo-mechanical properties, are greatly influenced by the 3HV content in the copoly­esters.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.46-50
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• 1999

The application of pulsed electric field was investigated in the crossflow ultrafiltration of BSA (bovine serum albumn) to economize the application time of electric current as well as to avoid inherent problems of long-term application of electric field. During the application of various cyclic patterns of pulsed electric current, the averaged filtration flowrate and the degree of concentration were maintained higher than those obtained in the absence of electric current application. The temperature increase, pH change, and BSA loss by electrodeposition were all negligible during the operation. The averaged filtration flowrate increased as the ON/OFF duration ratio of electric current was higher and as the period of ON/OFF cycle was shorter. The re-establishment of concentration polarization was dependent to the duration of current OFF state and, therefore, a longer duration of OFF state was not favorable in maintaining higher filtration flow rate. Although the averaged filtration flowrate was enhanced as the magnitude of electric current increased, the flowrate enhancement became smaller as the magnitude of current value above which the degree of electrokinetic depolarization is no further improved.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.11
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• pp.1557-1563
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• 2005

Ovarian follicular fluid contains both stimulatory and inhibitory agents that influence the growth and maturation of oocyte. In the present study, an attempt was made to isolate and study the biological properties of ovarian follicular fluid peptide(s) in buffaloes. Bubaline ovarian follicular was made steroid- and cell-free. A protein fraction was obtained by saturation (30-35% level) of the follicular fluid with ammonium sulfate. The protein fraction was purified with Sephadex-G 50 gel filtration chromatography and a single peak was obtained in the eluant volume, which was lyophilized. SDS-PAGE of the lyophilized fraction revealed a single band and the molecular weight of the peptide was 26.6 kDa. The peptide stimulated the cumulus cell expansion and in vitro maturation rate of oocytes in buffaloes in a dose dependent manner when it was incorporated at different dose levels (0, 10, 25, 50, 100 and 1,000 ng $ml^{-1}$ of maturation medium). The basic culture medium consisted of TCM 199 with Bovine serum albumin (0.3%). The in vitro maturation rates were comparable to those obtained with a positive control medium (TCM 199+20 ng EGF $ml^{-1}$+steer serum (20%)). Further purification and biological assays may throw more light on the nature and functions of this peptide.

• Corrosion Science and Technology
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• v.4 no.4
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• pp.147-154
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• 2005

The creep resistance of geogrids is one of the most significant long-term safety characteristics used as the reinforcement in slopes and embankments. The failure of geogrids is defined as creep strain greater than 10%. In this study, the accelerated creep tests were applied to polyester geogrids at various loading levels of 30, 50% of the yield strengths and temperatures using newly designed test equipment. Also, the new test equipment permitted the creep testing at or above glass transition temperature($T_g$) of 75, 80, $85^{\circ}C$. The time-dependent creep behaviors were observed at various temperatures and loading levels. And then the creep curves were shifted and superposed in the time axis by applying time-temperature supposition principles. The shifting factors(AFs) were obtained using WLF equation. In predicting the lifetimes of geogrids, the underlying distribution for failure times were determined based on identification of the failure mechanism. The results confirmed that the failure distribution of geogrids followed Weibull distribution with increasing failure rate and the lifetimes of geogrids were close to 100 years which was required service life in the field with 1.75 of reduction factor of safety. Using the newly designed equipment, the creep test of geogrids was found to be highly accelerated. Furthermore, the time-temperature superposition with the newly designed test equipment was shown to be effective in predicting the lifetimes of geogrids with shorter test times and can be applied to the other geosynthetics.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.1027-1036
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• 2005

Based on the correlation analysis result of preceding research, the biodegradabilities of cellulose fibers were closely related to the moisture regain of the samples, which reflects the hydrophilicity and internal structure of the fibers. In addition to this factor, it was expected that the biodegradation conditions influence the biodegradability of fibers. In this study, widely used cellulose fibers including cotton, rayon, and acetate were used. The biodegradabilities of cellulose fibers were measured by soilburial test, and then the degradation behaviors based on each condition were compared. Moreover, the effects of degradation conditions such as humidity of the soil were investigated. Changes in the internal structure of samples were also observed by X-ray analysis according to the soil burial time. It was shown that humidity of soil facilitated the degradation of cotton, rayon, and acetate fibers, showing higher degradation rate with higher humidity in soil. This effect was shown to be much greater in the fibers of high moisture regain such as cotton and rayon. In respect of microstructure change, crystallinities and their crystal size of fibers decreased remarkably in the soil of higher humidity. It was revealed that degradation of crystalline area was more dependent on the soil humidity than that of amorphous area.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.183-193
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• 1986

Full scale HDR containment experiment series pointed out that the previous containment analysis models have a number of shortcomings. One of them is on the calculational model of short term (0~2sec) pressure difference. The pressure differences between subcompartments are dependent on the flow rate, fluid density, head loss coefficient, and flow area ratio. It, however, is not known that any of them is largely attributed to the disagreement of pressure difference between the measured and the calculated values. In this study, the head loss coefficients are expressed with another form to improve the analytic model. The pressure and the pressure difference are evaluated by using COMPARE code with new correlation, and the results show better agreements with experimental values for V.42 test, but overestimate the measured values for V, 43 and underestimate for V.44.

• Herbal Formula Science
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• v.16 no.1
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• pp.79-94
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• 2008

Although inflammatory mediators such as nitric oxide(NO) and pro-inflammatory cytokines are involved in host defense mechanism, these overproduction contributes to the pathogenesis of several diseases such as otitis media, hearing loss, periodontitis, bacterial sepsis, rheumatoid arthritis, chronic inflammation and autoimmune diseases. We investigate the anti-inflammatory effects of water extract from Ji-Pae-San(JPSWE) fomulated with Angelica dahurica plus Fritillaria Verticillata, Angelica dahurica(ADWE), and Fritillaria Verticillata(FUVE) in vitro and in vivo. Each extract inhibited the production of inflammatory mediators(NO, $IL-1{\beta}$, IL-6, $TNF-{\alpha}$, and prostaglandin $E_2$) and the expression of inducible NO synthase(iNOS) and cyclooxygenase-2(COX-2) in lipopolysaccharide(LPS)-stimulated RAW 264.7 macrophages in a dose-dependent manner. These inhibitory effects were synergistically increased by their combination. JPSWE also inhibited $TNF-{\alpha}$, $IL-1{\beta}$, IL-6. and $PGE_2$ production as well as COX activity in LPS-stimulated mice. Moreover, JPSWE significantly suppressed death by LPS-septic shock in mice(survival rate: 100%). These results suggest that Ji-Pae-San may be useful for therapeutic drugs against inflammatory immune diseases, probably by suppressing the production of inflammatory mediators.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.10a
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• pp.365-373
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• 1999

Recently, numerous studies have demonstrated that artificial intelligence such as neural networks can be an alternative methodology for classification problems to which traditional statistical methods have long been applied. In building neural network model, the selection of independent and dependent variables should be approached with great care and should be treated as a model construction process. Irrespective of the efficiency of a learning procedure in terms of convergence, generalization and stability, the ultimate performance of the estimator will depend on the relevance of the selected input variables and the quality of the data used. Approaches developed in statistical methods such as correlation analysis and stepwise selection method are often very useful. These methods, however, may not be the optimal ones for the development of neural network models. In this paper, we propose a genetic algorithms approach to find an optimal or near optimal input variables for neural network modeling. The proposed approach is demonstrated by applications to bankruptcy prediction modeling. Our experimental results show that this approach increases overall classification accuracy rate significantly.