• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.429-438
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• 2011

In this study, the explicit numerical algorithm was proposed to simulate the stress erection process and ultimate-load analysis of the strarch (stressed arch) system. The strarch system is a unique and innovative structural system and member prestress comprising prefabricated plane truss frames erected through a post-tensioning stress erection procedure. The flexible bottom chord, which has sleeve and gap details, is closed by the reaction force of the prestressing tendon. The prestress imposed on the tendon will enable the strarch system to be erected. This post-tensioning process is called "stress erection process." During this process, plastic rigid-body rotation occurs to the flexible top chord due to the excessive amount of plastic strain, and the structural characteristic is unstable. In this study, the dynamic relaxation method (DRM) was adopted to calculate the nonlinear equilibrium equation of the system, and a displacement-based finite-element-formulated filament beam element was used to simulate the nonlinear behavior of the top chord sections of the strarch system. The section of the filament beam element was composed by the amount of filaments, which can be modeled by various material models. The Ramberg-Osgood and bilinear kinematic elastic plastic material models were formulated for the nonlinear material behaviors of the filaments. The numerical results that were obtained in the present study were compared with the experiment results of the stress erection and with the results of the ultimate-load analysis of the strarch unit frame. The results of the present studies are in good agreement with the previous experiment results, and the explicit DRM enabled the analysis of the post-buckling behaviors of the strarch unit frame.

• Tunnel and Underground Space
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• v.19 no.5
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• pp.388-396
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• 2009

Rock bolt is one of the most important supports for tunnelling to prevent excessive ground relaxation at the primary tunnel excavation stage. It forms a ground arch band by confining the ground around a tunnel. Rock bolt has various effects, such as support or hanging effect, internal pressure effect, arching effect, ground improvement effect etc. Most studies on rock bolt focused on the concept of support, but only a few researches on the ground reinforcing effect by pre-tensioning a rock bolts. In this study, large scale model tests are performed to investigate the ground reinforcing effect of rock bolts for regularly jointed rocks. Simple beam model was built to find out the reinforcing effect of jointed rocks, which was reinforced by pre-tensioned rock bolts. Settlement of model beam was analyzed through measuring its sagging for various installation intervals.

• The Korean Journal of Pharmacology
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• v.19 no.2
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• pp.25-34
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• 1983

In this isolated study, it was aimed to elucidate the pharmacological properties of non-cholinergic, non-adrenergic inhibitory responses in the longitudinal strips of rabbit portal vein. 1) The portal vein responded inhibitory to electrical field stimulation in a frequency - and calcium-dependent manner after pretreatment with atropine, guanethidine and ergotamine, simultaneously. 2) When exogenous ATP, ADP, adenosine and cyclic AMP were added, respectively, they only showed the relaxations in the higher concentration without mimicing or affecting the inhibitory response induced by the electrical stimulation. The antagonist of purine substances, neither quinine nor isobutyl-methyl xanthine did influence on the relaxation. 3) The inhibitory response was significantly increased in the presence of $1{\mu}g/ml 4-amino-pyrineine (4-AP) which is $K^+-conduction$ blockade, but higher concentration of 4-AP directly decreased the vascular tone. 4) Though repeated application of ATP revealed the inhibitory effect on the relaxation, however, that of adenosine resulted rather increase of the amplitude. 5) After pretreatment with $^3H-adenosine$, $^3H-efflux$ induced by ATP or adenosine was markedly enhanced, but the electrical stimulation caused less $^3H-efflux$. 6) ^3H-efflux by electrical stimulation was not affected by the administration 4-AP, tetrodotoxin and adenosine.

• Korean Journal of Plant Resources
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• v.33 no.5
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• pp.467-475
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• 2020

The purpose of this study is to investigate the vasodilatation effect of kirenol isolated from Sigesbeckia pubescens on the rabbit basilar artery. In this study, to determine the vasodilatation effect of kirenol on the rabbit basilar artery, arterial rings with intact or damaged endothelium were used for the experiment. And used an organ bath and force transducer were contracted by endothelin. Kirenol, major active constituents of S. pubescens, showed a moderate vasodilatation effect on the basilar arteries of rabbits. Therefore, treatment with kirenol may selectively accelerate cerebral blood flow through dilatation of the basilar artery. This result suggests a potential role of kirenol isolated from S. pubescens as a source of vasodilatation agent.

• Korean Journal of Cognitive Science
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• v.19 no.2
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• pp.163-175
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• 2008

Twelve Japanese students living in South Korea have been examined for their perceptual identification of an initial consonant in Korean syllables with or without a white noise. A confusion matrix was then subject to analyses of additive clustering, individual difference scaling, and probability of information transmission, the results of which were also compared to those of South Koreans. The Japanese in the present experiment confused /다/and/타/ most frequently, followed by /가/ and /카/, /자, 차, 짜/, /타/ and /따/, and so on. The results of additive clustering analysis of the Japanese significantly differed from those of the South Koreans. Individual difference scaling revealed dimensions of sonorant, aspiration and coronal. While South Koreans showed binary values on aspiration and tenseness dimensions, the Japanese did continuous values on such dimensions. An information transmission probability analysis revealed that the Japanese participants could not perceive very well such larynx features as tenseness and aspiration compared to the South Korean participants. The former group, however, perceived very well place of articulation features such as labial and coronal. The present results suggest that an approach dealing with structures of base representations is important in understanding the phonological categories of languages.