• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.116-120
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• 2001

The impactive Pressure wave induced by pyro valve in the pressurization system of KSR-III may result in fatal failure or malfunction of valves, so it is important to know the pressure wave characteristic in the pressurization system. An unsteady flow analysis in the simplified pressurization system was peformed by Finite difference method.

• Journal of the Korean Society of Safety
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• v.2 no.3
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• pp.21-27
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• 1987

The effect of plastic deformation in an interfacial crack is considered. Yield zones are assumed to have the form of a strip along the interface. The crack is subjected to mode III loads at infinity and lies along the interface of two semi-infinite planes with different material properties. The size of the yield zones, the relation between the size of the yield zone and CTOD are obtained in a closed form solution. The J integral also can be obtained in a closed form Solution.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.3
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• pp.159-169
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• 2019

Purpose: The purpose of this study was to provide an effective method of exercise therapy for patients with cervicogenic headache. Methods: The subjects were divided into the following three groups according to the intervention received: cervix-stabilizing exercise (n=12, group 1), transcranial direct current stimulation (n=12, group 2), and cervix-stabilizing exercise combined with transcranial direct current stimulation (n=12, group 3). The intragroup and intergroup differences in muscle characteristics and neck disability index were compared and analyzed. Results: The comparison and analysis of the changes in muscle tone and post hoc analysis revealed statistically significant intragroup decreases in the upper trapezius and suboccipitals in groups I and III, and statistically significant intergroup differences in the upper trapezius, with greater changes in group III than in group II, and in the suboccipitals, with greater changes in groupIII than in groups Iand II. The comparison and analysis of the change in muscle stiffness and post hoc analysis revealed a statistically significanti ntra group decrease in the upper trapezius in group Iand suboccipitals in group III, and a statistically significant intergroup difference in both muscles, with greater change in group III than in group II. The comparison and analysis of change in neck disability index and post hoc analysis revealed a statistically significant intragroup decrease in all the three groups and a statistically significant intergroup difference, with greater change in group III than in groups I and II. Conclusion: The neck-stabilizing exercise and transcranial direct current stimulation were shown to be effective in decreasing the tone of the cervical muscles by stabilizing the cervical bone and improving muscle durability, and in improving the movement and limitation of joint range of motion by decreasing muscle tone and stiffness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.725-728
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• 2004

In this study, the effect of mode II by variation of multilevel loading direction was experimentally investigated in the fatigue crack propagation behavior. To generate mixed-mode I+II loading state, the compact tension shear(CTS) specimen and loading device were used in this tests. The experimental method divided into three steps and three cases that were step I(0$^{\circ}$), step II(30$^{\circ}$, 60$^{\circ}$, 90$^{\circ}$),step III(0$^{\circ}$) and case I(0$^{\circ}$ ⇒ 30$^{\circ}$ ⇒ 0$^{\circ}$), case II(0$^{\circ}$ ⇒ 60$^{\circ}$ ⇒ 0$^{\circ}$), case III(0$^{\circ}$ ⇒ 90$^{\circ}$ ⇒ 0$^{\circ}$). The result of test, the step II affected to the step III in the all case. Specially, The fatigue crack propagation rate was faster and the fatigue life was smaller than of mixed mode I+II(30$^{\circ}$,60$^{\circ}$) due to the effect of mode II in the step III of the case III

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.64.2-64.2
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• 2017

The Population III (Pop III) stars are thought to be massive. If massive Pop III stars form binary system and they experience mass transfer via the Roche lobe overflow, this may significantly change the properties of the system. For example, mass transfer in such system may shorten the period of the system, forming short period binary black hole (BBH) system, which is the most promising candidate for recently detected gravitational wave radiation sources. Also, there is an expectation that due to the stripped envelope of donor star by mass transfer, this system can play a significant role in the cosmic reionization by emitting more UV photons. However, this outcome highly depends on the initial properties of the system. We perform grid calculation on Pop III binary models with various initial primary masses (20 ~ 100 solar mass), initial separations, and initial mass ratios (q = 0.5 ~ 0.9). We find that 1) in most cases binary models show no increase in the number of ionizing photons and 2) formation of short period BBH system via mass transfer is highly unlikely.

• Korean Journal of Pharmacognosy
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• v.26 no.4
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• pp.385-389
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• 1995

MeOH extract of Gastrodia elata was fractionated to five solvent fractions, hexane fr (fr I), 90% MeOH fr (fr II), EtOAc fr (fr III), BuOH fr (fr IV) and $H_2O$ fr (fr V). Among the five fractions, fr II, III and IV showed platelet anti-aggregating effects against ADP or collagen induced rat platelet aggregation in vitro. Fr II , III and IV were also tested in vivo, in the mouse and rat models of thrombosis. Oral administration of fr II, III or IV enhanced the recovery from the thrombotic shock in the mouse model of thrombosis to 32-40% from 17% of recovery with the control group of mice. Treatment with fr II, III or IV also attenuated the sudden reduction in the blood platelet count following intravenous collagen injection to rat. The above results were indicative of the presence of anti-platelet and anti-thrombotic components in this plant.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.81-84
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• 1999

The aqueous geochemical characteristics of Cr(III) and Cr(Ⅵ) in environmental systems are very different from one another: Cr(Ⅵ) is highly soluble, mobile and toxic relative to Cr(III) Reduction of Cr(Ⅵ) to Cr(III) are beneficial in aquatic systems because of the transformation of a highly mobile and toxic species to one having a low solubility in water, thus simultaneously decreasing chromium mobility and toxicity. Fe(II) species are excellent reductants for transforming Cr(Ⅵ) to Cr(III), and in addition, keeping Cr(III) concentrations below the drinking water standard of 52 ppb at pH values between 5 and 11. Investigations of the effects of NOM on Cr(Ⅵ) reduction are for examining the feasibility of using ferrous iron to reduce hexavalent chromium in subsurface environments. Experiments in the presence of soils, however, showed that the solid phase consumes some of the reducing capacity of Fe(II) and makes the overall reduction kinetics slower. The soil components bring about consumption of the ferrous iron reductant. Particular attention is devoted to the complexation of Fe(II) by NOM and the subsequent effect on Cr(Ⅵ) reduction. Cr(Ⅵ) reduction rate by Fe(II) was affected by the presence of NOM (humic acid), The effects of humic acid was different from the solution pH values and the concentration of humic acid. It was probably due to the reactions between humic acid and Cr(Ⅵ), humic acid and Fe(II), and between Cr(Ⅵ) and Fe(II), at each pH.

• Advances in environmental research
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• v.1 no.2
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• pp.167-179
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• 2012

Pistachio shell (Pistacia vera) (PS), a low-cost material, has been utilized for the removal of the Cr(VI) ions after treatment with citric acid. Batch experimental steps were applied to obtain Cr(VI) ion adsorption details for the equilibrium between Cr(VI) and modified pistachio shell (MPS). The influences of contact time, pH, adsorbent dose and initial chromium concentration on the adsorption performance of MPS was investigated in detail. The results displayed that adsorption of Cr(VI) by MPS reached to equilibrium after 2 h and after that a little change of Cr(VI) removal efficiency was observed. The sorption percent is higher at lower pH and lower chromium concentration. Two possible mechanisms for reduction of Cr(VI) to Cr(III) can be suggested in Cr(VI) removal. In the first mechanism, Cr(VI) is reduced to Cr(III) by surface electron-donor groups of the adsorbent and the reduced Cr(III) forms complexes with adsorbent or remains in the solution. This Cr(III) is not adsorbed by adsorbent at pH 1.8. But in second mechanism, the adsorption-coupled reduction of Cr(VI) to Cr(III) occurred on the adsorbent sites. The equilibrium sorption capacity of Cr(VI) ion after 2 h was 64.35 mg/g for MPS.

• Journal of the Korean Chemical Society
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• v.68 no.3
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• pp.139-145
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• 2024

This study aims to elucidate the mechanism involved in the hydrolysis of the hexacyanoferrate(III) complex ion (Fe(CN)₆^3-) and the mechanism leading to the formation of Prussian blue (Fe^III₄[Fe_II(CN)₆]₃·xH₂O, PB) in acidic aqueous solutions at moderately elevated temperatures. Hydrolysis constitutes a crucial step in generating PB through the widely used single-source or precursor method. Recent PB syntheses predominantly rely on the single-source method, where hexacyanoferrate(II/III) is the exclusive reactant, as opposed to the co-precipitation method employing bare metal ions and hexacyanometalate ions. Despite the widespread adoption of the single-source method, mechanistic exploration remains largely unexplored and speculative. Utilizing UV-vis spectrophotometry, negative-ion mode liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and a devised reaction, this study identifies crucial intermediates, including aqueous Fe^2+/3+ ions and hydrocyanic acid (HCN) in the solution. These two intermediates eventually combine to form thermodynamically stable PB. The findings presented in this research significantly contribute to understanding the fundamental mechanism underlying the acid-catalyzed hydrolysis of the hexacyanoferrate(III) complex ion and the subsequent formation of PB, as proposed in the sequential mechanism introduced herein. This finding might contribute to the cost-effective synthesis of PB by incorporating diverse metal ions and potassium cyanide.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.2
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• pp.99-103
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• 1997

The bacteriophages lytic for Vibrio furnissi, Vibrio fluvialis and Vibrio parahaemolyticus were isolated from fish gills and shellfish. Nucleic acid of bacteriophages was prepared and restriction endonuclease profile was compared. All isolates contained deoxyribonucleic acid. V. furnissi bacteriophage from fish gills showed 2 bands with Bgl II, 1 with Pst, 3 with Hind III, I with Bam HI and 2 with EcoR 1. V fluvialis phage represented 7 fragments with Bgl II, 1 with Pst, 4 with Hind III, and 2 with EcoR 1. V. parahamolyticus produced 13 sites with Hind III and 4 sites with EcoR 1. The fragment types were varied depending on the phage isolation. All three phages were digested with Hind III and EcoR I with different sizes. V. furnissi phage were digested with 5 different restriction enzymes.