• 전자공학회논문지S
• /
• 제36S권10호
• /
• pp.40-50
• /
• 1999

서비스의 다양화, 고기능화, 고객의 요구에 부응하는 통신 네트워크에 대한 새로운 요구가 일어나고 있다. 따라서 ATM 전달망의 특징을 이용한 개방형 네트워크 구조에 대한 연구가 활발히 이루어지고 있다. 본 논문에서는 ATM 네트워크의 전달망을 스위치 네트워크로 이용하는 VSN(Virtual Switch Network) 개념을 IMT-2000 스위칭 시스템에 적용하고, 호 처리과정을 이용하여 VSN의 특성을 평가한다. 이 결과를 기본으로 VSN 기반 제어계 집약형 ATM-MSC 노드 구조를 제시하고, 호 처리 절차를 이용하여 VSN의 특성을 평가한다. 그 결과, 3.5msec 정도의 호 처리 지연을 허용하면, CCCP(Call and Connection Control Processor)를 중심으로 반경 100km내에서 VSN을 이용한 ATM-MSC 시스템 구성이 가능함을 나타낸다. 그리고 VSN 개념을 적용한 ATM-MSC 시스템 구성의 가능성과 VSN의 타당성을 분명히 한다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제11권5호
• /
• pp.207-213
• /
• 2007

This study was designed to characterize ureteral smooth muscle motility and also to study the effect of forskolin(FSK) and isoproterenol(ISO) on smooth muscle contractility in murine ureter. High $K^+$(50 mM) produced tonic contraction by $0.17{\pm}0.06mN$(n=19). Neuropeptide and neurotransmitters such as serotonin($5{\mu}M$), histamine($20{\mu}M$), and carbarchol(CCh, $10{\sim}50{\mu}M$) did not produce significant contraction. However, CCh($50{\mu}M$) produced slow phasic contraction in the presence of 25 mM $K^+$. Cyclopiazonic acid(CPA, $10{\mu}M$), SR $Ca^{2+}$-ATPase blocker, produced tonic contraction(0.07 mN). Meanwhile, inhibition of mitochondria by protonophore carbnylcyanide m-chlorophenylhydrazone(CCCP) also produced weak tonic contraction(0.01 mN). The possible involvement of $K^+$ channels was also pursued. Tetraethyl ammonium chloride(TEA, 10 mM), glibenclamide($10{\mu}M$) and quinidine($20{\mu}M$) which are known to block $Ca^{2+}$-activated $K^+$ channels($K_{Ca}$ channel), ATP-sensitive $K^+$ channels($K_{ATP}$) and nonselective $K^+$ channel, respectively, did not elicit any significant effect. However, $Ba^{2+}$($1{\sim}2mM$), blocker of inward rectifier $K^+$ channels($K_{IR}$ channel), produced phasic contraction in a reversible manner, which was blocked by $1{\mu}M$ nicardipine, a blocker of dehydropyridine-sensitive voltage-dependent L-type $Ca^{2+}$ channels($VDCC_L$) in smooth muscle membrane. This $Ba^{2+}$-induced phasic contraction was significantly enhanced by $10{\mu}M$ cyclopiazonic acid(CPA) in the frequency and amplitude. Finally, regulation of $Ba^{2+}$-induced contraction was studied by FSK and ISO which are known as adenylyl cyclase activator and $\beta$-adrenergic receptor agonist, respectively. These drugs significantly suppressed the frequency and amplitude of $Ba^{2+}$-induced contraction(p<0.05). These results suggest that $Ba^{2+}$ produces phasic contraction in murine ureteral smooth muscle which can be regulated by FSK and $\beta$-adrenergic stimulation.