• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.563-571
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• 2003

Dysfunction of mesangial cells has been contributed to the onset of diabetic nephropathy. Insulin like growth factors (IGFs) are also implicated in the pathogenesis of diabetic nephropathy. However, it is not yet known about the effect of high glucose on IGF-I and IGF-II secretion in the mesangial cells. Furthermore, the relationship between cAMP and high glucose on the secretion of IGFs was not elucidated. Thus, we examined the mechanisms by which high glucose regulates secretion of IGFs in mesangial cells. Glucose increased IGF-I secretion in a time- (>8 hr) and dose- (>15 mM) dependent manner (p<0.05). Stimulatory effect of high glucose on IGF-I secretion is predominantly observed in 25 mM glucose (high glucose), while 25 mM glucose did not affect cell viability and lactate dehydrogenase release. High glucose also increased IGF-II secretion. The increase of IGF-I and IGF-II secretion is not mediated by osmotic effect, since mannitol and L-glucose did not affect IGF-I and IGF-II secretion. 8-Br-cAMP mimicked high glucose-induced secretion of IGF-I and IGF-II. High glucose-induced stimulation of IGF-I and IGF-II secretion was blocked not by pertussis toxin but by SQ 22536 (adenylate cyclase inhibitor). Rp-cAMP (cAMP antagonist), and myristoylated protein kinase A (PKA) inhibitor amide 14-22 (protein kinase A inhibitor). These results suggest that cAMP/PKA pathways independent of Gi protein may mediate high glucose-induced increase of IGF-I and IGF-II secretion in mesangial cells. Indeed, glucose (>15 mM glucose) increased cAMP formation. In conclusion, high glucose stimulates IGF-I and IGF-II secretion via cAMP/PKA pathway in mesangial cells.

• Korean Journal of Mathematics
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• v.18 no.4
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• pp.395-407
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• 2010

In this paper, we prove the generalized Hyers-Ulam stability of the following quadratic functional equations $$cf\(\sum_{i=1}^{n}x_i\)+\sum_{j=2}^{n}f\(\sum_{i=1}^{n}x_i-(n+c-1)x_j\)\\=(n+c-1)\(f(x_1)+c\sum_{i=2}^{n}f(x_i)+\sum_{i<j,j=3}^{n}\(\sum_{i=2}^{n-1}f(x_i-x_j\)\),\\Q\(\sum_{i=1}^{n}d_ix_i\)+\sum_{1{\leq}i<j{\leq}n}d_id_jQ(x_i-x_j)=\(\sum_{i=1}^{n}d_i\)\(\sum_{i=1}^{n}d_iQ(x_i)\)$$ in random normed spaces.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.40-49
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• 1996

In this paper, we studied channel assignment and handover schemes for the indoor microcell systems. For efficient frequency spectrum reuse we proposed the high quality reassignment (HQR) scheme. Proposed HQR scheme tries to keep the reuse distances small by monitoring C/I of channels being used. To assign a channel for a new or handove call, the scheme checks C/I of all available channels. Then HQR assigns the channel that has C/I near the threshold value, A_TH. The scheme also checks C/I of ongoing calls and continuously reassigns a new channel when needed. It attempts handover not only when C/I gets below a handover threshold value, HO_TH, but also when C/I becomes above a high quality reassignment threshold, H_TH. The performance of the proposed HQR scheme was analyzed by a computer simulation configuraed. The performance of the scheme was also analyzed for various threshold values selected and the results are presented in this paper. The results show that HQR scheme perfomrs better than the scheme adopted for DECT.

• Electrical & Electronic Materials
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• v.1 no.1
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• pp.70-77
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• 1988

This paper describes the influence of the electrode materials, moisture content, electrolyte density, temperature, surface state, ion absorbent on the C.T.I of phenolic resin by the I.E,C, 112 method. C.T.I are increased for electrode materials with low hydrogen overvoltage and high soluble point. Increusing moisture content of samples increased by logarithmical on the droplet number to tracking breakdown. Increasing electrolyte temperature region above 70-80(.deg.C) decreased hydrogen over-voltage, following the density changes are decreased by C.T.I=1/aD$^{2}$-bD+C.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.894-901
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• 2007

This study investigated the effects of cell cultured Acanthopanax senticosus extract (ASE) supplementation and swimming exercise on lipid profiles and carnitine concentrations in C57BL/6J mice fed high fat diets. Male C57BL/6J mice (n=50), aged 4 weeks, were divided into 5 groups based on exercise and/or ASE supplementation (0.5 g/kg of body weight): normal diet (N-C), high fat diet (H-C), high fat diet non-supplement & exercise (H-NSE), high fat diet supplement & no exercise (H-SNE), high fat diet supplement & exercis (H-SE). Liver nonesterified carnitine (NEC) was significantly higher in the H-SNE group than in the H-C group, and liver total carnitine (TCNE) levels were significantly higher in the H-SNE group than in the H-NSE and H-SE groups. Liver and muscle carnitine palmitoyltransferase-I (CPT-I) mRNA levels tended to be higher with ASE supplementation and/or exercise. These results suggest that supplementation with ASE and/or exercise might have a role in improving lipid oxidation.

• Polymer(Korea)
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• v.38 no.4
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• pp.496-501
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• 2014

Polyalphaolefin (PAO) is a synthetic lubricant that is superior to mineral-based lubricants in terms of physical and chemical characteristics such as low pour point (PP), and high viscosity index (VI). This paper first reports a novel preparation route for a synthetic lubricant via alkylation of isoparaffins using a peroxide initiator without olefin. Alkylation of three kinds of isoparaffins such as i-$C_{16}$, i-$C_{18}$, and i-$C_{23}$ as well as alkylation of i-$C_{18}$ with 2-pentene using di-tert butyl peroxide initiator were conducted under various conditions to confirm alkylation reaction from isoparaffins themselves i.e; Single-molecule alkylation. Various properties of each alkylates (VI and PP) were investigated as a synthetic lubricant. Single-molecule alkylation made from i-$C_{16}$ a,nd i-$C_{18}$ showed ultra high VI (>140) and low PP (< $-30^{\circ}C$).

• Journal of Ginseng Research
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• v.33 no.1
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• pp.26-32
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• 2009

Diabetic nephropathy is associated with the dysfunction of proximal tubule cells. Insulin-like growth factor 1(IGF-I) has also been considered to play an important role in the development of diabetic nephropathy. Ginsenosides have been used as a remedy for diabetes in Asian countries. Therefore, we examined the preventive effect of ginsenosides against high glucose-induced alteration of IGF-I secretion in the primary cultured proximal tubule cells. In present study, Ginseng saponin (GS) completely blocked high glucose-induced stimulation of IGF-I secretion in proximal tubule cells, whereas panaxatriol (PI) and panaxadiol (PD) partially suppressed. In addition, high glucose stimulated cAMP formation and protein kinase C(PKC) activity from cytosolic to membrane fraction. GS completely prevented high glucose-induced stimulation of cAMP and PKC activity while PT and PD partially did. Furthermore, high glucose-induced stimulation of IGF-I was blocked by the treatment of PKI (protein kinase A inhibitor) and bisindolylmaleimide I (protein kinase C inhibitor). In conclusion, GS prevented high glucose-induced dysfunction of proximal tubule cells.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.266-271
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• 2014

The Electromagnetic Interference(EMI) generating from corona discharge of transformer area can interference the digital Instrument and Control(I&C) systems located nearby transformers. When the potential gradient of the electric field around the conductor is high enough to form a conductive region but not high enough to cause electrical breakdown to nearby objects, the EMI of corona discharge emits with the conducted and radiated noise and it interferences the signals of the I&C systems. Since digital I&C systems have an efficiency and competitive price, the analog I&C systems have been upgraded and displaced with the digital I&C systems but which have less EMI Immunity. There was no assessment to I&C systems by EMI generating corona discharge nearby transformers. When the safety-related I&C systems are installed in plants, the verification of equipment EMI should be done not in site-specific test but in test facilities. There are the need to do the site-specific EMI evaluation of corona discharge nearby transformers. This paper assesses the margin between plant emission limits and the highest composite plant emission of corona. When the non safety-related I&C systems are placed in transformer area, it suggests the appropriate radiated susceptibility level to EMI of corona discharge.

• IE interfaces
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• v.12 no.2
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• pp.193-204
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• 1999

Development of high technology especially in telecommunication and precise weapon systems will impact the future battle field environment. So it is not difficult to anticipate the environment of military command and control system will be changed rapidly. Considering these future battle field environment, military needs automated C4I (Command, Control, Communication, Computer and Intelligence) system, namely real time decision support system which is combined high technologies. Most of advanced countries have been studied and developed these kinds of systems and already applied these systems in real military operations. In order to take a military initiative in Korea peninsula it is essential to catch up with this trend and procure C4I system. The purpose of this research is to present the method and the direction of optimal C4I system development model. First we survey the related theory about C4I systems. Second we present the conceptual framework for C4I system concept development. Third we model the system using Timed Petri-Net and perform simulation. Finally we analyze the through-put time and suggest alternatives. If we model using the real organization structure, operational tasks and various situations then optimal C4I system would be developed.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.86-89
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• 2004

The present study reports the preparation of a compact ZSM-5 membrane showing high thermal stability and high separation factors, especially n-/i-butane isomers at high temperatures. ZSM-5 membrane was prepared on a porous $\alpha$-Al$_2$O$_3$ tube (an average pore diameter, ca. 100 nm) at 18$0^{\circ}C$ by the seed-assisted crystallization method. The XRD and SEM results showed that a thin zeolite layer (ca. 1 ${\mu}{\textrm}{m}$) was formed on the support surface. The single gas permeances of $N_2$, H$_2$, SF$_{6}$, n-butane, and i-butane were taken at 27$0^{\circ}C$. i-Butane permeance hardly changed after repeated thermal treatments up to 40$0^{\circ}C$, indicating the membrane is thermally stable. On the other hand, other single gas permeances increased when the membrane was further dried at 40$0^{\circ}C$, indicating thermal pretreatment at 27$0^{\circ}C$ could not remove all the adsorbed species in the membrane. i-Butane and SF$_{6}$ permeances were significantly lower than the permeances of smaller molecules, indicating that the membrane has a low concentration of defects. The ideal selectivities at 27$0^{\circ}C$ were 61 for $H_2$/i-butane and 47 for $H_2$/SF$_{6}$. The temperature dependency of n/i-butane ideal selectivities and separation factors for an equimolar n/i-butane mixture was studied. The ideal selectivity showed a maximum of 36 at 30$0^{\circ}C$. The separation factors increased with temperature and reached around 12 at 300-40$0^{\circ}C$, which were much higher than those reported in the literature.ature.