• Structural Engineering and Mechanics
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• v.43 no.3
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• pp.287-309
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• 2012

Precast segmental bridge columns (PSBC) are alternatives for monolithic cast-in-situ concrete columns in bridge substructures, with fast construction speed and structural durability. The analytical tool for common use is demonstrated applicable for seismic performance prediction of PSBCs through experiment conducted earlier. Then the analytical program was used for parameter optimization of PSBC configurations under reversal cyclic loading. Shear strength by pushover analysis was compared with theoretical prediction. Moreover, seismic response of PSBC with energy dissipation (ED) bars was compared with its no ED bar counterpart under three history ground acceleration records. The investigation shows that appropriate ED bar and post-tensioned tendon arrangement is important for higher lateral bearing capacity and good ductility performance of PSBCs.

• Journal of Power Electronics
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• v.14 no.5
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• pp.852-858
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• 2014

A novel 12/10 axial field switched reluctance motor (AF-SRM) is proposed for cooling fan applications in this paper. Unlike from conventional structures, the proposed motor uses the axial field instead of the radio field, the rotor is constructed from a series of discrete segments, and the stator poles are constructed from two types of stator poles: exciting and auxiliary poles. This concept improves the torque capability of a previous design by reducing the copper volume, which leads to a higher efficiency. To verify the proposed structure, the finite element method (FEM) and Matlab-Simulink are employed to get characteristics of the proposed SRM. Finally, a prototype of the proposed motor was tested for characteristic comparisons.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.46-52
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• 2003

In this study, the full scale testing method of the geogrid-reiuorced soil Segmental Retaining Walll(SRW) under the simulated train loading were proposed in order to evaluate the applicability of reinforced soil SRW in railway embankment. The train loading was simulated by the design static wheel load and the impact coefficient due to the train passing velocity. This test was focused on the static performance of reinforced soil SRW in terms of the following measuring systems ; the horizontal earth pressure displacement acting on the facing block and the tensile strain along the geogrid. The data gathered from this full scale testing was compared with numerical analysis results by FLAC.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1217-1221
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• 1998

We present results of molecular dynamic (MD) simulations for the segmental motion of liquid n-heptadecane in order to investigate conformational transitions from one rotational isomeric state to another. The behavior of the hazard plots for n-heptadecane obtained from our MD simulations are compared with that for polymer of Brownian dynamics (BD) study. The transition rate at the ending dihedrals of the n-heptadecane chain is much higher than that at the central dihedrals. In the study of correlation between transitions of neighboring dihedrals, the large value of c2 implies that some 30% of the transitions of the second neighbors can be regarded as following transitions two bonds away in a correlated fashion. Finally the analysis of multiple transitions and the number of times occurred in the initial 0.005 ns are discussed.

• Bulletin of the Korean Chemical Society
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• v.6 no.6
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• pp.354-358
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• 1985

Carbon-13 nuclear spin-lattice relaxation times have been measured over the range of temperature from 213K to 353K for carbons in n-heptane in neat liquid. The experimental data have been analyzed to obtain informations of segmental motions in the chain polymers by employing a model which describes jumps between several discrete states with different lifetimes. The overall reorientation of the molecule is assumed to be isotropic rotational diffusion. From the above analysis the activation energies of each C-C bond reorientation as well as the overall reorientation have been obtained through the Arrhenius-type temperature dependence.

• Structural Engineering and Mechanics
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• v.81 no.4
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• pp.513-522
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• 2022

Steel-concrete composite segments replacing the conventional reinforced concrete segments can provide the rectangular shield tunnel superiorities on bearing capacity, ductility and economy. A simplified model with high-efficiency on computation is proposed for investigating the nonlinear response of the rectangular tunnel lining composed of composite segments. The simulation model is developed by an assembly of nonlinear fiber beam elements and spring elements to express the transfer mechanism of forces through components of composite segments, and radial joints. The simulation is conducted with the considerations of material nonlinearity and geometric nonlinearity associated with the whole loading process. The validity of the model is evaluated through comparison of the proposed nonlinear simulation with results obtained from the full-scale test of the segmental tunnel lining. Furthermore, a parameter study is conducted by means of the simplified model. The results show that the stiffness of the radial joint at haunch of the ling and the thickness of inner steel plate of segments have remarkable influence on the behaviour of the lining.

• The Korean Journal of Nuclear Medicine
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• v.34 no.6
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• pp.487-496
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• 2000

Purpose: The aim of this study is to investigate the reproducibility of the quantitative assessment of segmental wall motion and systolic thickening provided by an automatic quantitation algorithm. Materials and Methods: Tc-99m-MIBI gated myocardial SPECT with dipyridamole stress was performed in 31 patients with known or suspected coronary artery disease (4 with single, 6 with two, 11 with triple vessel disease; ejection fraction $51{\pm}14%$) twice consecutively in the same position. Myocardium was divided into 20 segments. Segmental wall motion and systolic thickening were calculated and expressed in mm and % increase respectively, using $AutoQUANT^{TM}$ software. The reproducibility of this quantitative measurement of wall motion and thickening was tested. Results: Correlations between repeated measurements on consecutive gated SPECT were excellent for wall motion (r=0.95) and systolic thickening (r=0.88). On Bland-Altman analysis, two standard deviation was 2 mm for repeated measurement of segmental wall motion, and 20% for that of systolic thickening. The weighted kappa values of repeated measurements were 0.807 for wall motion and 0.708 for systolic thickening. Sex, perfusion, or segmental location had no influence on reproducibility. Conclusion: Segmental wall motion and systolic thickening quantified using $AutoeUANT^{TM}$ software on gated myocardial SPECT offers good reproducibility and is significantly different when the change is more than 2 mm for wall motion and more than 20% for systolic thickening.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.1
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• pp.98-102
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• 2005

• Physical Therapy Korea
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• v.19 no.2
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• pp.20-28
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• 2012

The lumbar multifidus muscle, which can be separated into deep fascicles (DM) and superficial fascicles (SM), is important for lumbar segmental stability. However, no previous studies have investigated the effect of lumbar stabilization exercises on the thickness of DM and SM. Thus, the purpose of this study was to assess DM thickness after three different lumbar segmental stabilization exercises. In total, 30 healthy male participants were recruited and randomly assigned to one of three exercise groups: hollowing in the quadruped position (H-Quad), contralateral arm and leg lift (CALL), and bilateral arm and leg lift (BALL). Each lumbar segmental stabilization exercise was conducted over 4 weeks. Ultrasonography was used to compare the DM and SM thickness before and after the 4 weeks of exercise. A mixed-model analysis of variance using Scheffe's post-hoc test was used for statistical analysis. The results showed a significant effect for the measurement time (before vs. after 4 weeks of exercise) in the DM (F=31.26, p<.05) and SM (F=4.56, p<.05). At the end of the 4 weeks, the DM thickness had increased significantly in the H-Quad exercise group, and the SM thickness had increased significantly in the CALL and BALL exercise groups. Also in the BALL exercise group, the SM thickness was greater compared with that in the H-Quad exercise group. These findings suggest that the thickness of the DM and SM were increased by different types of lumbar segmental stability exercise after 4 weeks.

• Structural Engineering and Mechanics
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• v.20 no.6
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• pp.673-693
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• 2005

A general step-by-step simulation for the time-dependent analysis of segmentally-erected prestressed concrete box-girder bridges is presented. A three dimensional finite-element model for the balanced-cantilever construction of segmental bridges, including effects of the load history, material nonlinearity, creep, shrinkage, and aging of concrete and the relaxation of prestressing steel was developed using ABAQUS software. The models included three-dimensional shell elements to model the box-girder walls and Rebar elements representing the prestressing tendons. The step-by-step procedure allows simulating the construction stages, effects of time-dependent deformations of materials and changes in the structural system of the bridges. The structural responses during construction and throughout the service life were traced. A comparison of the developed computer simulation with available experimental results was conducted and good agreement was found. Deflection of the bridge deck, changes in stresses and strains and the redistribution of internal forces were calculated for different examples of bridges, built by the balanced-cantilever method, over thirty-year duration. Significant time-dependent effects on the bridge deflections and redistribution of internal forces and stresses were observed. The ultimate load carrying capacities of the bridges and the behavior before collapse were also determined. It was observed that the ultimate load carrying capacity of such bridges decreases with time as a result of time-dependent effects.