• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.466-471
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• 2004

Efficient numerical finite element analysis of creeping concrete structures requires the use Kelvin or Maxwell chain model, which is most conveniently identified from a continuous retardation or relaxation spectrum, the spectrum in turn being determined from the given compliance or relaxation function. The method of doing that within the context of solidification theory for creep with aging was previously worked out by Bazant and Xi, but only for the case of a continuous retardation spectrum based on Kelvin chain. The present paper is motivated by the need to incorporate concrete creep into the recently published microplane model M4 for nonlinear triaxial behavior of concrete, including tensile fracturing and behavior under compression. In that context. the Maxwell chain is more effective than Kelvin chain. because of the kinematic constraint of the microplanes used in M4. Determination of the continuous relaxation spectrum for Maxwell chain. based on the solidification theory, is outlined and numerical examples are presented.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.17-26
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• 2008

The traveling salesman problem is to find tours through all cities at minimum cost ; simply visiting the cities only once that a salesman wants to visit. As such, the traveling salesman problem is a NP-complete problem ; an heuristic algorithm is preferred to an exact algorithm. In this paper, we suggest an effective cost relaxation using a candidate arc set which is obtained from a regression function for the traveling salesman problem. The proposed method sufficiently consider the characteristics of cost of arcs compared to existing methods that randomly choose the arcs for relaxation. For test beds, we used 31 instances over 100 cities existing from TSPLIB and randomly generated 100 instances from well-known instance generators. For almost every instances, the proposed method has found efficiently better solutions than the existing method.

• Applied Science and Convergence Technology
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• v.24 no.3
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• pp.47-52
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• 2015

The correlation between admittance and dielectric spectroscopy of dielectric relaxation in lead scandium noibate, have been investigated. Lead scandium niobate, with composition $PbSc_{0.5}Nb_{0.5}O_3$, was prepared by conventional solid state synthesis. Conductance Y'(G), susceptance Y"(B) and capacitance C of lead scandium niobate as a function of frequency and temperature were measured. From the temperature-dependence of RLC circuit, insight into physical significance of the dielectric properties of lead scandium niobate is obtained. The relative strong frequency dependent of dielectric properties in lead scandium niobate is observed, and the phase transition occurred at a broad temperature region. Also, the value of critical exponent ${\gamma}$=1.6 showed on heating process. The long relaxation times part enlarged diffuse by conductivity effects with increasing temperature, and the ordering between $Sc^{3+}$ and $Nb^{5+}$ in PSN influences complex admittance and dielectric properties. Confirmed the typical characteristic of lead-type relaxor in the Raman spectra of lead scandium niobate and major ranges are between 400 and $900cm^{-1}$.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.103-106
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• 2000

We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.514-519
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• 2008

The non-separable quadratic penalty terms create an inherent difficulty when applying the standard augmented Lagrangian relaxation(ALR) method for decomposing the unit commitment problem into independent subproblems. This paper presents a separable augmented Lagrangian relaxation method for solving the unit commitment problem. The proposed method is designed to have a separable structure by introducing the quadratic terms with additional auxiliary terms in the augmented Lagrangian function. Numerical results are presented to validate the effectiveness of the proposed method.

• Journal of Chest Surgery
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• v.28 no.8
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• pp.742-746
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• 1995

The present study was aimed at investigating possible transmitter mechanisms in the endothelial cell layer in regulating the tone of the vascular smooth muscle. The thoracic aorta was isolated from the anesthetized male white rabbits and its helical strips were prepared. Electrical field stimulation was delivered to platinum wire electrodes positioned parallel to the vessel segment preconstricted with phenylephrine [3.5x10-6 mol/L at a distance of 1.5-2.0 mm. The electrical stimulation [70 V, 5 msec, 0.5-200 Hz caused either relaxation only [34% or a biphasic response [prolonged relaxation following a weak and transient contraction, 66% . The relaxation response was frequency- dependent, and at 200 Hz a complete relaxation was noted. Mechanical rubbing of the endothelial layer abolished or greatly attenuated the relaxation. The relaxation was also markedly attenuated in the presence of NG-nitro- L-arginine methyl ester [10-3mol/L or procaine hydrochloride [3.5x10-4mol/L . Tetrodotoxin,guanethidine, atropine or indomethacin failed to block or enhance the relaxation response to electrical field stimulation. It is concluded that the vascular endothelium in the aorta contains diffusible substances that regulates the function of the smooth muscle layer, in which relaxation is more prominent than contraction. Their release by the electrical stimualtion in vitro may not involve classic neuronal transmitter release mechanisms or metabolism of arachidonic acids by cyclooxygenase. The release of the relaxing agents may require an increase in cytosolic calcium level. The chemical nature of the relaxant may be, to a large extent, nitric oxide.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.2
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• pp.93-106
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• 2004

This paper studied a maximal covering location problem with cost restrictions, to maximize level of service within predetermined cost. It is assumed that all demand have to be met. If the demand node is located within a given range, then its demand is assumed to be covered, but if it is not, then its demand is assumed to be uncovered. An uncovered demand is received a service but at an unsatisfactory level. The objective function is to maximize the sum of covered demand, Two heuristics based on the Lagrangean relaxation of allocation and decoupling are presented and tested. Upper bounds are found through a subgradient optimization and lower bounds are by a cutting algorithm suggested in this paper. The cutting algorithm enables the Lagrangean relaxation to be proceeded continually by allowing infeasible solution temporarily when the feasible solution is not easy to find through iterations. The performances are evaluated through computational experiments. It is shown that both heuristics are able to find the optimal solution in a relatively short computational time for the most instances, and that decoupling relaxation outperformed allocation relaxation.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.4
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• pp.1078-1082
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• 2004

The purpose of this study was to investigate the possibility of medicinal plants application as an edible functional food resources. We carried out to develop a traditional functional beverage by using hot-water extraction of 4 medicinal plants(Polygonatun sibiricum, Ophiopogonis radix, Lycii fructus, Schizandriae fructus) and we examined the effects of drink on physiological function in aorta relaxation. Thus, the effect of developed beverage on phenylephrine induced contraction of isolated rat thoracic aorta. Contractile force was measured with force displacement transducer under 1.5g loading tension. Brix, pH and titratable acidity of developed drink were 9.5%, 3.3 and 0.22%. The approximate nutritional composition of beverage was carbohydrate, 5.98%, crude protein, 0.70%, crude fat, 0.20% and crude ash, 0.20%. Developed beverage contained K(4.00 ㎎%), Na(3.68 ㎎%), Ca(2.54 ㎎%), Mg(1.60 ㎎%) and Fe(0.29㎎%). The contraction forces by injection of phenylephrine in isolated thoracic aorta were significantly low in each experimental groups compared with control groups, These results that developed drink with medicinal plants can be used as a functional material to decrease aorta contraction.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.356-358
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• 1989

Linear and nonlinear complex permittivities have been measured for an alternating copolymer of vinylidene cyanide(VSCN) with vinyl propionale(VPr). It is found that the third order permittivity ${\varepsilon}_3$ depends upon frequency according to a function V ${\varepsilon}_3$/ ${1+(j{\omega}{\tau}_3)^{\beta}}^3$ while the linear permittivity ${\varepsilon}_1$obeys a Debye type function ${\nabla}{\varepsilon}_1$/ {1+$(j{\omega}{\tau}_1)^{\beta}$}. Experimental results are well fitled by predicted functions except at low frequency where dc conduction dominates. The relaxation times ${\tau}_1$ and ${\tau}_3$ at same teperature are nealy equal and depend upon temperature according to WLF form. The relaxation strengths ${\nabla}{\varepsilon}_1$ and ${\nabla}{\varepsilon}_3$ have a peak at the vicinity of glass transition temperature (Tg). The strength ${\nabla}{\varepsilon}_1$ has a value of -9 order and ${\nabla}{\varepsilon}_3$ has a negative value of -25 order. The analysis of mechanism by combined knowledge about linear and nonlinear permittivities and dipole moment gives us an imformation of the electrical and thermal dipolar motions in this copolymer.

• YAKHAK HOEJI
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• v.54 no.5
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• pp.392-397
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• 2010

The aim of present study was to investigate the possible influence and related mechanism of additional alcohol on the flavonoid- induced arterial relaxation. Agonist-induced vascular smooth muscle contractions involve the activation of thick or thin filament pathway. However, there are no reports addressing the question whether this pathway is involved in quercetin-induced relaxation cotreated with alcohol in rat aortae contracted with phorbol ester, fluoride or thromboxane $A_2$ mimetic U-46619. We hypothesized that cotreated alcohol plays a role in vascular relaxation evoked by quercetin in rat aortae. Endothelium-denuded arterial rings from male Sprague-Dawley rats were used and isometric contractions were recorded using a computerized data acquisition system. Quercetin inhibited phorbol ester, fluoride or thromboxane $A_2$-induced contraction regardless of endothelial function. However, alcohol didn't decrease any agonist-induced contraction. Interestingly, only in thromboxane $A_2$-induced contraction, synergistic results were observed in aortae denuded and cotreated with quercetin and alcohol suggesting that additional pathways different from antioxidation or endothelial nitric oxide synthesis might be involved in the vasorelaxation. In conclusion, in the agonists-contracted rat aortae, quercetin and alcohol together showed synergistic response regardless of endothelial function in an agonist-dependent manner.