• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.36.1-36.1
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• 2018

Understanding the origin of strong galactic outflows and the suppression of star formation in dwarf galaxies is a key problem in galaxy formation. Using a set of radiation-hydrodynamic simulations of an isolated dwarf galaxy, we show that the momentum transferred from resonantly scattered Lyman-alpha(LyA) photons can suppress star formation by a factor of two in metal-poor galaxies by regulating the dynamics of star-forming clouds before the onset of supernova explosions (SNe). This is possible because each LyA photon resonantly scatters and imparts ~10-300 times greater momentum than in the single scattering limit. Consequently, the number of star clusters predicted in the simulations is reduced by a factor of ~5, compared to the model without the early feedback. More importantly, we find that galactic outflows become weaker in the presence of strong LyA radiation feedback, as star formation and associated SNe become less bursty. We also examine a model in which radiation field is arbitrarily enhanced by a factor of up to 10, and reach the same conclusion. The typical mass-loading factors in our metal-poor dwarf system are estimated to be ~5-10 near the mid-plane, while it is reduced to ~1 at larger radii.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.2
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• pp.299-307
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• 2009

The purposes of this study ate to evaluate sensibility performance of metallic Jacquard fabrics, and to contribute to the research and development of the women's suit made of the metallic Jacquard fabrics. eight fabrics were woven with two kinds of warp yarns(nylon and rayon) and weft yarn blended with various contents(0, 7, 14, 21%) of metallic yarn. The sensibility performances such as sensory, touch preference and buying preference for memory fabrics of the metallic Jacquard fabrics were evaluated, and mechanical properties were measured by KES-FB system. The correlation between the mechanical properties and the sensibility performance were analyzed. As the metal fiber content increased, the sensory evaluation value of lustered, wrinkly, sandy, rustle and stiff increased, the sensory evaluation value of slippery and damp decreased. As the metal fiber content increased, the touch preference decreased and the buying preference increased. The touch preference had negative correlation with the metal fiber content, but the buying preference had positive correlation with it.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.39-50
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• 2005

Electrolytic reduction of uranium oxide to uranium metal was studied in a $LiCl-Li_{2}O$ molten salt system. The reduction mechanism of the uranium oxide to a uranium metal has been studied by means of a cyclic voltammetry. Effects of the layer thickness of the uranium oxide and the thickness of the MgO on the overpotential of the cathode and the anode were investigated by means of a chronopotentiometry. From the cyclic voltamograms, the decomposition potentials of the metal oxides are the determining factors for the mechanism of the reduction of the uranium oxide in a $LiCl-3\;wt{\%} Li_{2}O$ molten salt and the two mechanisms of the electrolytic reduction were considered with regards to the applied cathode potential. In the chronopotentiograms, the exchange current and the transfer coefficient based on the Tafel behavior were obtained with regard to the layer thickness of the uranium oxide which is loaded into the porous MgO membrane and the thickness of the porous MgO membrane. The maximum allowable currents for the changes of the layer thickness of the uranium oxide and the thickness of the MgO membrane were also obtained from the limiting potential which is the decomposition potential of LiCl.

• Steel and Composite Structures
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• v.17 no.2
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• pp.145-157
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• 2014

This study aimed to investigate the fatigue crack growth behavior of a kind of fiber metal laminates (FML) under four different stress levels. The FML specimen consists of three 2024-T3 aluminum alloy sheets and two layers of glass/epoxy composite lamina. Tensile-tensile cyclic fatigue tests were conducted on centrally notched specimen at four stress levels with various maximum values. A digital camera system was used to take photos of the propagating cracks on both sides of the specimens. Image processing software was adopted to accurately measure the length of the cracks on each photo. The test results show that: (1) a-N and da/dN-a curves of FML specimens can be divided into transient crack growth segment, steady state crack growth segment and accelerated crack growth segment; (2) compared to 2024-T3 aluminum alloy, the fatigue properties of FML are much better; (3) da/dN-${\Delta}K$ curves of FML specimens can be divided into fatigue crack growth rate decrease segment and fatigue crack growth rate increase segment; (3) the maximum stress level has a large influence on a-N, da/dN-a and da/dN-${\Delta}K$ curves of FML specimens; (4) the fatigue crack growth rate da/dN presents a nonlinear accelerated increasing trend to the maximum stress level; (5) the maximum stress level has an almost linear relationship with the stress intensity factor ${\Delta}K$.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.685-689
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• 2000

The complexation reaction between Pb2+,TI and Cd2+ions and macrocyclic ligands, 18-crown-6 ( 18C6) and dibenzo- 18-crown-6 (DB 18C6), was studied in dimethylsulfoxide (DMSO)-nitromethane (NM) and dimethyl-formamide (DMF)-nitromethane binary system s by square wave polarography (SWP) technique. The stoichiometry and stability of the complexes were determined by monitoring the shifts in half-waves or peak potentials of the polarographic waves of metal ions against the Iigand concentration. In most cases, the stability constants of complexes increase with increasing amounts of the nitromethane in mixed binary solvents used in this study. The complexes formed between 18C6 and DB18C6 and these metal cations in all cases had a stoichiometry of 1 : 1. The results obtained show that there is an inverse relationship between the formation constant of complexes and the donor number of solvents based on a Gatmann donocity scale and the stability constants show a high sensitivity to the composition of the mixed solvent systems. A linear behavior was observed for variation of log Kf of I8C6 complexes vs the composition of the mixed solvent systems in NM/DMSO and NM/DMF,but a non-linear behavior was observed in the case of DB 18C6 complexes in these binary systems. In most of the systems investigated, the Pb2+ cation forms a more stable complex with the 18C6 than other two cations and the order of selectivity of this Iigand for cations is: Pb2+ > TI+,Cd2+.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.737-750
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• 2022

Timber-Concrete Composite construction system consists of combining timber beam or deck and concrete with different connectors. Different fastener types are used in Timber-Concrete Composite systems. In this paper, the effects of two types of fasteners on structural behavior are compared. First, the notches were opened on timber beam, and combined with reinforced concrete slab by fasteners. This system is called as Notched Connection System. Then, timber beam and reinforced concrete slab were combined by new type designed fasteners in another model. This system is called as Notched-Slab Approach. Two laboratory models were constructed and bending tests were performed to examine the fasteners' effectiveness. Bending test results have shown that heavy damage to concrete slab occurs in Notched Connection System applications and the system becomes unusable. However, in Notched-Slab Approach applications, the damage concentrated on the fastener in the metal notch created in the slab, and no damage occurred in the concrete slab. In addition, non-destructive experimental measurements were conducted to determine the dynamic characteristics. To validate the experimental results, initial finite element models of both systems were constituted in ANSYS software using orthotropic material properties, and numerical dynamic characteristics were calculated. Finite element models of Timber-Concrete Composite systems are updated to minimize the differences by manual model updating procedure using some uncertain parameters such as material properties and boundary conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.300-304
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• 2010

This study was performed to development a dental three-dimensional laser scanning system and measure the accuracy of new adjustable upper dental impression tray. The metal stock, individual, and new adjustable stock trays were used for 30 stone casts(10 casts each) duplicated a resin master model of maxilla. The dental stone was poured in a vinyl polysiloxane impressions and allowed to set for on hour. The master model and the duplicated casts were digitized using an dental scanning system. The distance between the reference points were measured and analyzed on the graphic image of 3D graphic software of CATIA. The statistical significance of the differences between the groups was determined by a two-way ANOVA. There were no significant differences between the accuracies of the adjustable stock tray and the master model except only anterior arch width on the upper arch. The adjustable upper stock tray showed clinically acceptable accuracies of the study cast produced by them.

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1012-1019
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• 2004

The synthesis of novel group 9 metal complexes containing the S,S'-chelate ligands, $Li_2S_2C_2B_{10}H_{10}$ (2a) and $LiS(S=PMe_2)C_2B_{10}H_{10$} (2b), is described. Two new dinuclear complexes of the type $[{(cod)M}_2(S,S'-S_2C_2B_{10}H_{10})]$ (cod = 1,5-cyclooctadiene; M = Rh (3a), or Ir (3b)) were synthesized by the reaction of chloridebridged dimers $[M({\mu}-Cl)(cod)]_2$ with one molar equivalent of the corresponding dilithium dithiolato ligand $Li_2S_2C_2B_{10}H_{10}$ (2a). X-ray crystal structure analysis of 3a revealed a dinuclear structure in which each (cod)Rh unit is attached to a distinct sulfur atom of a 1,2-dithio-o-carboranyl ligand (2a). Additionally, the electrochemical properties of 3a and 3b were investigated by cyclic voltammetry. In an analogous manner, reaction of the lithium dithiolato ligand $LiS(S=PMe_2)C_2B_{10}H_{10}$ (2b) with $Cp^{\ast}CoI_2(CO)$ produced a mononuclear dithiolato complex, $[Cp^{\ast}CoI{(S,S'-S(S=PMe_2)C_2B_{10}H_{10})}]$ (4), which was characterized by single-crystal X-ray analysis.

• Analytical Science and Technology
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• v.19 no.4
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• pp.309-315
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• 2006

Two piperazine-templated metal sulfate complexes, $(C_4N_2H_{12})[Ni(H_2O)_6](SO_4)_2$, I and ($C_4N_2H_{12}$) $[Co(H_2O)_6](SO_4)_2$, II, have been synthesized by hydro/solvothermal reactions and their crystal structures analyzed by single crystal X-ray diffraction methods. Complex I crystallizes in the monoclinic system, $P2_1/n$ space group, a=12.920(3), b=10.616(2), $c=13.303(2){\AA}$, ${\beta}=114.09(1)^{\circ}$, Z=4, $R_1=0.030$ for 3683 reflections; II: monoclinic $P2_1/n$, a=12.906(3), b=10.711(2), $c=13.303(2){\AA}$, ${\beta}=114.10(2)^{\circ}$, Z=4, $R_1=0.032$ for 4010 reflections. The crystal structures of the piperazine-templated metal(II) sulfates demonstrate zero-dimensional compound constituted by diprotonated piperazine cations, metal(II) cations and sulfate anions. The structures of complex I and II are substantially isostructural to that of the previously reported our piperazine-templated copper(II) sulfate complex $(C_4N_2H_{12})[Cu(H_2O)_6](SO_4)_2$. The central metal(II) atoms are coordinated by six water molecules in the octahedral geometry. The crystal structures are stabilized by three-dimensional networks of the $O_{water}-H{\cdots}O_{sulfate}$ and $N_{pip}-H{\cdots}O_{sulfate}$ hydrogen bonds between the water molecules and sulfate anions and protonated piperazine cations. Based on the results of thermal analysis, the thermal decomposition reactions of the complex I was analyzed to have three distinctive stages whereas the complex II proceed through several stages.