• 한국세라믹학회지
• /
• 제32권4호
• /
• pp.471-481
• /
• 1995

Unirradiated UO2 pellets were pulverized by oxidation in air at 40$0^{\circ}C$, and the oxidized powders were reduced in H2 and CO atmospheres at $600^{\circ}C$. During the oxidation of UO2 at 40$0^{\circ}C$, intergranular cracks which caused the spallation were mainly developed by the volume contraction due to the formation of intermediate phase (U4O9 or U3O7). As oxidation proceeded, U3O8 finally formed. As the oxidation/reduction cycles were repeated, the powder surface became coarser, specific surface area was increased and average particle size was decreased. The sintered densities of the powder were increased by the oxidation/reduction cycle due to the characteristic changes of the powder.

• 시스템엔지니어링학술지
• /
• 제12권2호
• /
• pp.29-38
• /
• 2016

The threats around Korea Peninsula have been dramatically increased because North Korea is developing the Nuclear ballistic missile, Submarine launched ballistic missile(SLBM), and many kinds of weapons for sudden provocations. Therefore, ROK navy needs the cutting-edge warship combat systems in order to defeat the enemy threats effectively in the sea. The paper analyzes current warship combat system acquisition process and studies US navy and other advanced countries acquisition process and their contraction trends. After that, the paper proposes the optimal acquisition process of warship combat system for the ROK navy based on our current situation and other advanced countries acquisition trends. The paper will dedicate the next generation warship combat system acquisition process.

• 한국환경과학회지
• /
• 제17권7호
• /
• pp.809-816
• /
• 2008

The oriental ore minerals, which mainly consisted of talc, actinolite, sericite, and halloysite were developed, and then used to examine the healing effect on the skin wound in rats. Full-thickness square wounds were formed on the backs of rats after the hairs on the dorsal surface were shaved. The ore minerals were applied to examine the healing effect from day 0 to 15 after wounding. Notable wound healings in terms of congestion around the wound, wound contraction and epithelialization were found in ore mineral-treated groups. Moreover, microscopic results revealed the formation of epithelial layer, hair follicles and progressive angiogenesis in ore mineral-treated groups, while complete epithelial layer could not be found in the control. These results suggest that ore minerals from Korean indigenous ores may have wound healing effect on the skin injury in rats.

• 한국세라믹학회지
• /
• 제11권2호
• /
• pp.17-21
• /
• 1974

Miscibility of barium sulfate in tricalcium silicate was investigated by firing 3CaCO3·SiO2 mixture containing barium sulfate at 1530℃. Added amount of barium sulfate to the mixture was zero to 5 mole % with intervals of 1 mole %. Lattice parametres were also calculated. Results were as follow; 1) Dissolution of barium sulfate in tricalcium silicate does not alter the symmetry in room temperature, but influences it's polymorphic transition forms, temperatures and thermal effects; modification triclinic Ⅱ is stabilized in room temperature. 2) Barium sulfate dissolves about up to 2 mole % in tricalcium silicate and more than this amount, tricalcium silicate formation is inhibited. 3) Unit cell volume of tricalcium silicate is slightly decreased with dissolution of barium sulfate, mainly because of contraction in c axis.

• Journal of Pharmaceutical Investigation
• /
• 제14권2호
• /
• pp.86-91
• /
• 1984

A ginseng preparation (GP) consisting of ginseng ex., lycium fructus ex., four kinds of vitamines and caffein was evaluated for acute toxicity and general pharmacology. Average lethal doses $(LD_{50})$ of GP in male mice were 2,988mg/kg (i.p.) and more than 3g/kg (p.o.). In dosage of 300 and 900mg/kg (p.o.) showed no analgesic activity in both tests of the writhing method induced by acetic acid and of tail pressure method and no effect on the pentetrazole-induced convulsion. However, it appeared to have a hypothermic action only in dose of 900mg/kg. The duration of hypnosis induced by hexobarbital sodium in mice was shortened by GP, being probably due to caffein. GP Produced no marked contraction of isolated ileum and uterus in high concentrations of up to $1{\pm}10^{-3}g/ml$. These results suggested that GP did not show any considerable central nervous depressant activity and exhibited very weak actue toxicity in mice.

• 생약학회지
• /
• 제18권4호
• /
• pp.241-248
• /
• 1987

Woohwangchungsim-Won has been widely used for the treatment of appoplexy, hypertension, arteriosclerosis, insomnia and cerebrovascular accident, etc in oriental hospital and pharmacy. In order to investigate the efficacy of Woohwangchungsim-Won, the water extract of it were bioassayed for isolated ileum, blood vessels, blood pressure, heart and diuresis. The results of this studies were as follows; Spontaneous motilities of isolated ileum of mice were strongly suppressed, and contraction of isolated ileum of mice and guinea-pigs induced by acetylcholine chloride, barium chloride and histamine were inhibited. Vaso-dilating action due to vascular smooth muscle relaxation in frogs and rabbits, and hypotensive action in anesthetized rabbits were noted. Negative inotropic action on the isolated frog heart and diuretic effect in rabbits were shown.

• 반도체디스플레이기술학회지
• /
• 제16권4호
• /
• pp.25-29
• /
• 2017

In this paper, we have studied the deformation problem of the scaffold caused by the FDM type 3D printer. The Practical TRIZ technique was used to solve the deformation problem of the scaffold generated from the adhesion surface between the scaffold and the bed. The Practical TRIZ methodology was used to derive the solution and the experiment was conducted on the derived solution. As a result of evaluating the experimental results obtained for the solution, it was found that the deformation of the scaffold was much improved to the satisfactory level.

• Nonlinear Functional Analysis and Applications
• /
• 제28권2호
• /
• pp.473-495
• /
• 2023

The use of mathematical modelling in the study of epidemiological disorders continues to grow substantially. In order to better support global policy initiatives and explain the possible consequence of an outbreak, mathematical models were constructed to forecast how epidemic illnesses spread. In this paper, fractional derivatives and (${\varpi}$ - F_𝓒)-contractions are used to explore the existence and uniqueness solutions of the novel coronavirus-19 model.

• 대한본초학회지
• /
• 제25권4호
• /
• pp.17-21
• /
• 2010

Objectives : The aim of this study was to evaluate the differential mechnism of vasodilation of alcohol steamed Rhei Tangutici Radix et Rhizoma. (ART) and Rhei Tangutici Radix et Rhizoma. (RT) in rat thoracic aorta. Methods : Rat aortic ring preparations were mounted in organ baths with oxygenated (95% $O_2$-5% $CO_2$) Krebs-Ringer bicarbonate solutions at $37{\pm}0.5^{\circ}C$ and subjected to contractions or relaxations. Results : ART exerted vasorelaxation on phenylephrine(PE)-induced contraction in a dose dependent manner. Vasorelaxation effects of ART and RT were endothelium-independent. In the $Ca^{2+}$-free high KCl (60 mM) baths, the contraction of aortic rings induced by accumulative addition of $Ca^{2+}$ (0.3-10.0 mM) was significantly reduced by pre-treatment with both ART and RT for 10 min. The magnitude of vasodilatation was biggerin ART. Moreover, verapamil ($0.001{\mu}M$) and diltiazem ($10{\mu}M$), voltage operative $Ca^{2+}$channel blockers, attenuated the relaxation effect of ART but not that of RT. In the absence of extracellular $Ca^{2+}$, pre-incubation of the aortic rings with RT ($1.0mg/m{\ell}$) significantly reduced the contraction caused by PE but not that of ART. $K^+$ channel inhibitors such as glibenclamide (Gli, $10^{-5}M$), tetraethylammonium (TEA, 1 mM) and 4-aminopyridine (4-AP, 0.2 mM) significantly reduced the ART's vasorelaxation efficacy, but not that of RT. However, the relaxation effects of ART and RT were not inhibited by pre-treatment with indomethacin ($10^{-5}M$), and atropine ($10^{-6}M$). Conclusions : These results suggest that the endothelium-independent relaxation is due to inhibition of $Ca^{2+}$ influx via the suppression of $Ca^{2+}$ release from intracelluar store in RT but via both voltage operative $Ca^{2+}$channel blockage and $K^+$ channel activation in ART.

• 대한약리학회지
• /
• 제10권1호
• /
• pp.55-59
• /
• 1974

Further elucidation of the mechanism of halothane's negative inotropic action has resulted from a study of the effect of various substrates on halothane-depressed rat atria. Approximately 6 mg% halothane was required to maintain a 50% depression of the contractility of rat atria suspended in a modified Krebs-Ringer bicarbonate glucose medium, pH 7.4, $30^{\circ}C$ for 2hr. Both lactate and acetate were found to restore partially the contractility of halothane-depressed atria. The maximally effective concentration of lactate was 5 mM; for acetate it was 2.5mM. Neither 5 nor 20 mM of additional glucose was effective in restoring the force of contraction of halothane-depressed atria. The results are consistent with the hypothesis that halothane exerts at least a part of its negative inotropic effect on rat atria by inhibiting either the uptake or utilization of glucose by the myocardium. The site of blockade must be prior to the conversion of pyruvate to acetyl CoA. In our previous report dealing with the mechanism of cardiac depressant action of inhalation anesthetic halothane, it has been demonstrated that: 1) approximately 6 mg/100 ml halothane is required to maintain 50% depression of the force of contraction of isolated rat atria in Krebs-Ringer bicarbonate glucose medium; 2) pyruvate partially restores the contractility of halothane-depressed atria, but has no effect on normal atria; the partial recovery of depressed atria by the addition of sodium pyruvate is due to the effect of the pyruvate ion itself, not to the sodium ion; 4) addition of pyruvate, to atria depressed with hypertonic medium, produced only further depression. From these findings we concluded that the cardiac depressant action of halothane on rat atria is a manifestation of inhibition of glucose uptake or utilization. The present studies were undertaken to observe the effect of other substrates on halothane-depressed atria in order to substantiate our conclusion. As with the case of pyruvate, lactate and acetate also partially restored the force of contraction of halothane-depressed atria. These data are consistent with the hypothesis that halothane inhibits glucose uptake or utilization in the glycolytic cycle of the myocardium.