• Structural Engineering and Mechanics
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• v.47 no.3
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• pp.383-399
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• 2013

High-strength strands are widely used as a key structural element in cable-stayed bridges and prestressed concrete structures. Conventional strands for stay cable and tendons in prestressed concrete structures are ${\phi}$15.7mm coated seven-wire strands and ${\phi}15.2mm$ uncoated seven-wire strands, respectively, but the ultimate strengths of both strands are 1860MPa. The objective of this paper is to investigate the tensile behavior of a newly developed ${\phi}15.7mm$ 2,200 MPa coated strand and a ${\phi}15.2mm$ 2,400 MPa uncoated strand according to various types of mono anchorages and to propose appropriate anchorages for both strands. Finite element analyses were initially performed to find how the geometry of the anchor head affects the interaction among the anchor head, the wedge and the strand and to find how it affects the stress distributions in both parts. Tensile tests for the new strands were carried out with seven different types of mono anchorages. The test results were compared to each other and to the results obtained from the tensile tests with a grip condition. From the analysis and the test results, desirable mono anchorages for the new strands are suggested.

• Journal of the Korean Chemical Society
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• v.14 no.1
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• pp.51-59
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• 1970

The apparent molal volumes(${\phi}_v$) of the homologous salts $RNH_3Cl$, where R varies from methyl-($CH_{3^-}$) to n-butyl-(n-$C_4H_{9^-}$) in a series of methanol-water mixtures have been determined at 30$^{\circ}C$ by means of a float method to fifth decimal places down to 0.01 m. The values of ${\phi}_r$ extrapolated to infinite dilution give partial molal volumes $\bar{V}^{\circ}$which varies considerably in accordance with the solvent composition. that is, mole fraction of methanol. The experimental results are discussed in terms of the varying size and charge effect, hydrophobic nature of the solute species, and also the additivity relationship between successive homologous and the structure of the binary solvent. The results indicate that at 0.1 mole fraction methanol the enhanced structuredness of water cause a minimum in the partial molal volumes of cations $\bar{V}^{\circ}_+$, while at 0.4 mole fraction the solvent structure is such that the free volume is a minimum but the effect of electrostriction is a maximum.

• Journal of KIISE:Software and Applications
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• v.30 no.7_8
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• pp.642-648
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• 2003

In this paper, we are interested in checking equivalence of FSMs(finite state machines). Two FSMs are equivalent if and only if their responses are always equal with each other with respect to the same external stimuli. Equivalence checking FSMs makes complicated FSM be substituted for simpler one, if they are equivalent. We can also determine the system satisfies the requirements, if they are all written in FSMs. In this paper, we regard equivalence checking problem as model checking one. For doing so, we construct the product model $M ={M_A} {\beta}{M_B} from two FSMs ${M_A} and {M_B}$. And we also get the temporal logic formula ${\Phi}$ from the equivalence checking definition. Then, we can check with model checker whether if satisfies ${\Phi}$, written $M= {.\Phi}$. Two FSMs are equivalent, if $M= {.\Phi}$ Otherwise, it is not equivalent. In that case, model checker generates counterexamples which explain why FSMs are not equivalent. In summary, we solve the equivalence checking problem with model checking techniques. As a result of applying to several examples, we have many satisfiable results.

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.2
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• pp.93-100
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• 2002

Comparison results of callus formation ratio from seed explants, callus sizes, regeneration ratios from callus and regeneration efficiency [calculated by following formular; callus formation ratio(%) ${\times}$ regeneration ratio(%)/100] for 27 ochardgrass (Dactylis glomerata L.)varieties imported and Hapsung 2 developed in Korea are as follows; 1. Among ochardgrass varieties showing more than 50% callus formation ratios, the descending order of callus formation ratio after bedding the seed explants for 4 weeks was 93M>Sparta> Pizza>Condor>Lidaglo>Glorus>Hapsung 2>Frode. 2. The callus sizes after bedding for 4 weeks were in the range of $\Phi$ 0.43cm~4.2cm in which there was 10 times size difference between the largest one and the smallest one but most of them were between ${\Phi}2.5cm~4cm$. 3. The regeneration ratio from callus among varieties were in the range of 0~36% and descending order of the upper 6 varieties was Plano>Akimidori>Justus>Lidacta>Currie>Hall mark. 4. The regeneration efficiency which is calculated by the ratios of regeneration from seed explant numbers was between 0 to 17.4% among which Justus showed the highest value in the 4-week treatment. 5. The correlation between callus formation ratios and the callus sizes, callus formation ratios and regeneration efficiency, and callus sizes and regeneration efficiency were r=0.5765, r=0.6365 and r=0.6246, respectively in 4-week callus and all the correlations were significant on the 1% level. 6. In 6-week callus, the descending order callus formation ratios from seed explants fur the best 6 varieties was Condor>Sparta>93 M>Justus>Potomac>Lidaglo>Frode. 7. The callus sizes formed were between ${\Phi}1.5~5.7cm$ in which Sparta, the largest one of ${\Phi}5.7cm$ was five times larger than the smallest one. The callus size of the control variety, Hapsung 2 was ${\Phi}3.8cm$, which belonged to a larger size. 8. Regeneration ratio showed a great deviation among varieties from 6-week old calli by showing from 0% to 100% in which all the calli were regenerated in Piano while no callus was regenerated in Juno. 9. The range of regeneration efficiency was between 0~28% among varieties in which the values from 6-week callus treatment were larger than those from 4-week callus treatment. Especially, the value of Potomac in 6-week was 3 times larger than that in 4-week. 10. The correlation between callus formation ratios and the callus sizes, callus formation ratios and regeneration efficiency, and callus sizes and regeneration efficiency were r=0.5369, r=0.6683 and r=0.5937. respectively in 6-week callus, and all the correlations were significant on the 1% level.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.1
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• pp.10-16
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• 2004

The aim of this study is to investigate the process conditions on the microstructual changes and mechanical properties of large 7175 aluminum ring roll forgings. The billets range from 370 mm to 720 mm in diameter were homogenized and ring roll forged after direct chill casting. The tensile properties of ring roll forged specimen manufactured with ${\Phi}370mm$ billets were superior to those of ${\Phi}720mm$ billets under $T_6$ condition. Also, these properties showed better than those of military specification under $T_{74}$ treatment. The impact value of ring roll forged specimen under $T_{74}$ treatment increased up to 20% than that of $T_6$ condition. The fracture toughness of ring roll forged specimen manufactured with ${\Phi}370mm$ cast billet showed nearly same level of ${\Phi}720mm$ billet which was processed using MF or Cog free forging followed by ring roll forging.

• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.95-101
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• 1996

Variations of the leakage current behaviors and interface potential barrier $({\Phi}_B)$ of rf-sputter deposited (Ba, Sr)$TiO_3$ (BST) thin films with thicknesses ranging from 20 nm to 150nm are investigated as a function of the thickness and bias voltages. The top and bottom electrodes are dc-sputter-deposited Pt films. ${\Phi}_B$ critically depends on the BST film deposition temperature, postannealing atmosphere and time after the annealing. The postannealing under $N_2$ atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the ${\Phi}_B$ from about 2.4 eV to 1.6 eV due to the oxidation. ${\Phi}_B$ is not so dependent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films show Shottky emission current.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.33-42
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• 2002

Copolymerization of ${\alpha}$-Methylstyrene(AMS) with Acrylonitrile(AN) was carried out with benzoylperoxide(BPO) as an initiator in toluene at $80^{\circ}C$ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters and 3 hours, respectively. The monomer reactivity ratios, $r_{AMS}$ and $r_{AN}$ determined by both the Kele$T{\"{u}}d\"{o}s$ method and the Fineman-Ross method were $r_{AMS}$=0.16(0.14), $r_{AN}$=0.04(0.06). The cross-termination factor ${\Phi}$ of the copolymer over the entire AMS composition ranged from 0.75 to 0.92. The ${\Phi}$ factors of poly(AMS-co-AN) were increased with increasing AMS content. The simulated conversions and copolymerization rates were compared with the experimental results. It was observed that the average time to reach dynamic steady-state was three times the residence time.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4210-4214
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• 2011

Quasiclassical trajectory (QCT) calculations of Ne + ${H_2}^+$ reaction have been carried out on the adiabatic potential energy surface of the ground state $1^2$ A'. The reaction probability of the title reaction for J = 0 has been calculated, and the QCT result is consistent with the previous quantum mechanical wave packet result. Quasiclassical trajectory calculations of the four polarization-dependent differential cross sections have been carried out in the center of mass (CM) frame. The P(${\theta}_r$), P(${\phi}_r$) and P(${\theta}_r$, ${\phi}_r$) distributions, the k-k'-j' correlation and the angular distribution of product rotational vectors are presented in the form of polar plots. Due to the well in $1^2$ A' PES, the reagent vibrational excitation has greater influence on the polarization of the product rotational angular momentum vectors j' than the collision energy.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.68-74
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• 1993

The mixed convection heat transfer has been studied numerically for misaligned and parrallel arrays of two flat plates at 100.leg.Re.leg.700, 0.1.leg.B.leg.1.0, 0.2.leg.leg.PHI.$_{R}$.leg.1Gr=10$^{4}$ and Pr=0.71. For misaligned plates and parallel plates, the optimum plate spacings move to the narrow spacing as Reynolds number and .PHI.$_{R}$ increase and can be expressed by the correlation equations at Gr=10$^{4}$. The optimum plate spacings for parallel plates sharply move to the narrow spacing compared with misaligned plates. The maximum mean Nusselt number of parallel plates shows higher value than that of misaligned plates and can be expressed by the correlation equations at Gr=10$^{4}$.EX>.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.626-630
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• 2006

This study investigates the effects of Interaural Cross-correlation(IACC) and its variation on annoyance of the heavy-weight impact sounds. Subjects evaluated the annoyance of the heavy-weight floor impact sounds recorded in rooms of apartments which have different sound insulation treatments; furnished and occupied conditions are characterized by the ACF/IACF factors. A paired comparison test was conducted using the impact sound sources whose IACC and variation of IACC values were different. It was found that IACC is inversely correlated with the scale value(r=-0.62) whereas the variation of IACC is not(r=-0.34). On the contrary, ${\Phi}(0)$ is highly correlated with scale value of annoyance and ${\Phi}(0)$ is need to be controlled as constant to find the effect of IACC on annoyance.