• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.233-236
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• 2012

본 연구에서는 변성기용으로 사용되는 에폭시 복합체에 대해 절연 파괴 실험을 하고 그 데이터를 와이블 분포 확률을 이용해서 시뮬레이션을 하였다. 에스테르기의 기여에 의한 가교밀도 때문에 저온에서 경화제가 증가할수록 파괴강도가 증가하고 충진제를 첨가한 시료들의 파괴강도는 비충진 시료들의 경우 보다 더 낮았는데 이는 충진제 첨가가 계면을 형성하고 전하가 축적되어 분자의 이동도가 증가되고, 전계가 집중되어 전자 가속화 및 전자 사태의 성장이 초기에 도달되기 때문으로 사료된다. 또한 와이블 분포의 분석으로부터 허용 절연파괴 확률이 0.1[%]로 주어질 때, 인가 전계값은 21.5[kV/mm] 이하가 되어야 함을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.238-239
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• 2005

With the aim of developing XLPE insulation for extra high voltage cable, we investigated the morphology of cross-linked polyethylene. We used a kind of base materials and additives, and controlled curing condition and amount of additives. The effect of addition of additives on morphology of XLPE such as lamellar density, orientation and additive layer were analyzed using TEM analysis. We applied this result to diffused additive amount was analyzed using FT-IR analysis, and the change of microstructure as the degree of additive diffusion was analyzed using TEM analysis.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.375-378
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• 2004

In this paper, we fabricated pantacene TFTs using PVP copolymer and cross-linked PVP as gate insulator on glass and plastic (PET) substrate. Depending on the density of PVP and poly (melamine-co-formaldehyde) the performance has been changed. We obtained the best performance with the mobility of 0.12cm2/V sec and the on/off current ratio of $1.19{\times}10^6$ for the case of $10wt\%$ PVP copolymer mixed with $5wt\%$ poly(melamine-co-formaldehyde). Additionally using OTFTs with the above PVP gate insulator, we fabricated the integrated circuit including inverter which produced the gain of 5.56 on the glass substrate and gain of 9.7 on the plastic (PET) substrate. And the threshold voltage was respectively +8V and +14v$ldots$

• CELLMED
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• v.10 no.4
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• pp.31.1-31.6
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• 2020

Introduction: Dyslipidaemia is directly associated with cardiovascular diseases. Temperament, the unique constitutional make-up of an individual, is responsible for one's personality traits, physical appearances, and disease predispositions. The rising prevalence of dyslipidaemia becomes a challenge to control morbidity and mortality due to cardiovascular diseases. Objective: To study clinical patterns and risk factors of dyslipidaemia and its association with temperament at the individual level was the main objective of this study. Materials and Methods: It was a descriptive and analytical cross sectional study. The participants (n=88) were screened on the basis of raised serum lipid profile from the outpatient department of National Research Institute of Unani Medicine for Skin Disorders, Hyderabad. The data were collected on a case record form designed for this study and analyzed retrospectively. Results: In this study, there were 57% participants (n=50) of phlegmatic temperament in which mean total cholesterol, triglycerides, low density lipoprotein- cholesterol and high density lipoprotein-cholesterol were 230.92 (±49.48) mg/dl, 182.34 (±110.61) mg/dl, 153.24 (±50.21) mg/dl and 46.3 (±10.83) mg/dl respectively. Discussion: This study showed the prevalence of different clinical patterns of dyslipidaemia in the population and the phlegmatic participants were dyslipidaemic in a higher percentage. The prevalence of dyslipidaemia in phlegmatic participants may be linked to the constitutional make-up of the individual. The temperament of an individual may be considered as one of the risk factors for dyslipidaemia. Conclusion: It was concluded that the temperament of an individual may be used as a screening tool to predict the individual's tendency to develop dyslipidaemia.

• Journal of Nutrition and Health
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• v.36 no.2
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• pp.175-182
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• 2003

This study was conducted to examine whether bone mineral density changes in 55 young Korean college women aged 19 to 26 years over 2 years and nutritional and biochemical factors are related. Bone mineral density (BMD) was measured in the spine (LS), femoral neck (FN), ward's triangle (WT), and femoral trochanter (FT) by dual energy X-ray absorptiometry three times at one-year intervals. Serum osteocalcin (OC), parathyroid hormone (PTH), and urinary cross-linked N-teleopeptides of type collagen (NTx) were measured. Dietary intake was assessed 8 times with 24-hour recall method. Physical activity (PA) was obtained by questionnaire and body fat content was measured by bioelectrical impedance analysis at baseline and after 2 years. Analyses were performed on 34 subjects with all three BMD measurements. The BMDs at the lumbar spine gradually increased over 2 years, while the BMDs of three sites at the femur were sustained or increased. The mean OC, PTH had a similar pattern with the change of BMD at the femur. The mean NTx decreased over 2 years but was still higher than those in other studies. BMI, body fat, vitamin A and zinc intake had a significant correlation with LS-BMD. Femur, PTH, body fat, vitamin A, vitamin B$_2$and calcium intake had a significant correlation with WT-BMD and was mostly influenced by diet. By multiple regression analysis, it was shown that the significant factors affecting the LS-BMD were BMI and vitamin A intake and those affecting FN and WT were age, BMI, PTH and calcium intake. These results indicate that some Korean women still experience increases in BMD and that this was associated with PTH and vitamin A and calcium intake. Therefore, proper diet and diet management is needed to increase changes in BMD among college women.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.621-626
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• 2010

Anion exchange membranes can be used for reverse electrodialysis for electric energy generation, and capacitive deionization for water purification, as well as electrodialysis for desalination. In this study, anion exchange membranes of poly((vinylbenzyl) trimethylammonium chloride-2-hydroxyethyl methacrylate)/poly(vinyl alcohol) were prepared through the polymerization of (vinylbenzyl)trimethylammonium chloride and 2-hydroxyethyl methacrylate in aqueous poly(vinyl alcohol) solutions, esterification with glutaric acid, and cross-linking reaction with glutaraldehyde. We investigated electrochemical properties for the anion exchange membranes prepared according to experimental conditions. Ion exchange capacity and electrical resistance for the membranes were changed with a variation in the monomer ratio in polymerization. Water uptake and conductivity for the membranes decreased with an increase in the content of glutaric acid in esterification. The change in the time of crosslinking reaction with the formed film and glutaraldehyde affected electrochemical properties such as water uptake, conductivity, or transport number for the membranes. Chronopotentiometry and limiting current density for the anion exchange membranes prepared were measured.

• Membrane Journal
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• v.10 no.3
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• pp.148-154
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• 2000

Poly(vinyl alcohol)(PVA)/sulfur-siccinic acid(SSA) membrane performances have been studied for the vapor permeation separation of methyl tort-butyl ether(MTBE)/methanol mixtures with varying operation temperatures, amount of cross-linking agents, and feed compositions. 1'here are two factors, the membrane network and the hydrogen bonding, in the swelling measurements of PVA/SSA membranes. These two factors act interdependently on the membrane swelling. The sulfuric acid group in SSA took an important role in the membrane performance. The cross-linking effect might be more dominant than the hydrogen bonding effect due to the sulfuric acid group at 7% SSA membrane. Hydrogen bonding effect was more important for 5% SSA membrane. In vapor permeation, density or concentration of methanol in vapor feed is lower than that of methanol in liquid feed, as a result, the hydrogen bonding portion between the solvent and the hydroxyl group in PVA is reduced in vapor permeation. In this case, the 7% SSA membrane shows the highest separation factor of 2187 with the flux of 4.84g/$m^2$hr for MTBE/methanol=80/20 mixtures at 3$0^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.593-602
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• 1988

Polymer-supported crown ethers (Ps-CE) which can be used for phase-transfer catalyst (PTC) were synthesized for the purpose of allowing reusable function to ordinary crown ethers, and the kinetics of the liquid-solid-liquid triphase-catalyzed nucleophilic displacement reaction of iodide (aqueous phase) on 1-bromooctane (organic phase) using synthesized Ps-CE (solid) were studied. Ps-CE were obtained by grafting of hydroxymethyl crown ethers to 1~2% cross-linked chloromethylated polystyrene. All reactions followed a pseudo-first order dependency on the 1-bromooctane concentration and the observed rate constants $(k_{obsd})$ were linearly related to the molar equivalents of Ps-CE, and were subjected to the influence of cross-linking density of polymer backbone, solvent and the reaction temperature. The catalytic activity of Ps-CE was also compared with that of structurally similar soluble crown ethers, and used Ps-CE were easily recovered after the reaction by simple filtration and could be reused without loss of catalytic activity in the same anionic displacement reaction. Enthalpies and entropies of activation associated with the displacement were 10~20kcal $mol^{-1}, 20~55eu. respectively, and the free energy of activation was ~30kcal mol^{-1}$.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.3
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• pp.121-127
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• 2007

In this study, we investigated the therapeutic effects of a novel formulation of low-dose calcium and vitamin $D_3$ blended with Rehmannia glutinosa Libosch and Eleutherococcus senticosus Max (RE+), in postmenopausal women. The controls were given either a placebo or high dose calcium and vitamin $D_3$ (Ca + D). Bone mineral density (BMD) in the L2-3 lumber spines and femur regions was assessed, and serum osteocalcin, bone-specific alkaline phosphatase (BALP), and cross-linked N-telopeptide of type I collagen (NTx) were used as markers of osteoblast and osteoclast activity. Furthermore, all variables were measured before and after 6 and 12 months of treatment. The osteocalcin level was higher in the RE+ group, and BALP was almost the same in all groups. Serum NTx was significantly decreased in the RE+ group after 12 months (p<0.05). The NTx in the Ca + D and placebo groups showed no significant change. The decrease of femur BMD was further demonstrated in the placebo group, but significantly increased in the RE+ group after 6 and 12 months of treatment (p<0.05). There were significant differences in the percent changes of femur BMD between the placebo and RE+ groups (p<0.01) and Ca+D and RE+ groups (p<0.05). The decrease of spine BMD in the placebo group was inhibited both in the Ca + D and RE+ groups, however, there was significant difference only between the placebo and RE+ groups (p<0.05). These findings suggest that continuous oral therapy of the RE+ formulation reduces rapidly decreasing bone mineral density in postmenopausal women more effectively than high doses of calcium and vitamin $D_3$ alone by inhibiting osteoclastic activity. Therefore, it seems that the RE+ has its own antiosteoporotic effects. We suggest larger clinical studies to determine the most efficacious dosage and benefits of this novel treatment.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.71-76
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• 2013

The effect of zirconate having - NH functional group on the T-peel and lap shear strength of $CaCO_3$ containing structural epoxy adhesive for car body assembly was investigated. Curing behavior of epoxy adhesive samples were investigated by differential scanning calorimeter (DSC) techniques. The addition of zirconate up to 7.5 phr did not affect the curing mechanism of epoxy adhesive. While the small amount of zirconate addition less than 1.1 phr increased the cross-linking density, the excess addition of zirconate resulted in the increase of uncross-linked impurity. From the increase of T-peel and lap shear strength and the change of fracture mode from the adhesive failure to the mixed one, it was considered that the small addition of zirconate was effective in improving the adhesion strength of epoxy adhesive to the adherend and inorganic filler surfaces. The formation of uncross-linked impurity with the excess addition of zirconate was considered to decrease the joint strength by decreasing the cohesive strength of the cured epoxy.