• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.39-46
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• 2015

The purpose of this study is to analyze the deflection of the prestressed beams. In this paper, a finite element model for deflections of prestressed beams is presented. Proposed finite element model was verified comparing with existing experimental results, and it showed a good agreement with the experimental results. Also, a parametric study has been conducted to analyze the influence of eccentricity, span-depth ratio, and prestressing force. The finite element model results were compared with hand calculation results. Deflections were increased as the eccentricity decreases, the span-depth ratio increases, and the prestressing force decreases. Hand calculation overestimated the deflection when the eccectricity or prestressing force is too small.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.497-509
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• 2010

Five concrete-encased steel columns using high-strength steel($f_{ys}$=801MPa) and high-strength concrete($f_{ck}$=97.7MPa) were tested to investigate the eccentric axial load-displacement relationship. Test parameters included the type, yield strength, and spacing of lateral reinforcement, and also the eccentricity of axial load. To analyze the behavior of the column specimens, the nonlinear sectional analysis using strain-compatibility and confinement effect was performed. To examine the applicability of existing design codes for the composite sections using high-strength materials, the test results were also compared with the predictions by the nonlinear analysis and the design codes. The confinement effect of lateral reinforcement increased the ductility of concrete, and the moment capacity of the column specimens increased with the ductility of concrete. The prediction by the nonlinear analysis gave good agreement with the test results. On the other hand, the ACI 318 neglecting lateral confinement effect underestimated the strength of the column specimens, and the Eurocode 4 using complete plastic capacity of steel section overestimated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.241-250
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• 2011

The new gerotor developed in this paper has an inner rotor in which a circular arc is inserted between the hypocycloid and epicycloid curves, whereas the outer rotor is designed using the simulation results for the rotor and a modification method. The new gerotor has no cusps and loops and no limit on the eccentricity. We increase the average flow rate by adding a new design parameter, $\gamma$, which is the inclined angle of the inner rotor at the intersection of the hypocycloid and the circular arc. A calculation method to calculate the chamber area is also developed. This method can also be used to calculate the flow rate and flow rate irregularity when the contact points are unknown. The control of eccentricity and $\gamma$ is expected to lead to an efficient rotor.

• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.27-37
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• 2007

This research was conducted to determine the optimum lifting positions on precast concrete slabs for precast concrete pavement construction, based on the analysis of concrete stress distribution under various lifting conditions. To analyze stresses in concrete slabs, the finite element method was implemented and a numerical model of the precast slab that was going to be used in the experimental construction was developed. Changes in the stress distribution due to the lifting angle were investigated because slab lifting is not always performed in the perpendicular direction to the slab surface. In addition, the effect of the lifting level, the distance between the neutral axis of the slab and the lifting point, on the stress distribution was investigated since the lifting point is not always at the neutral axis of the slab. To consider the actual steel design of the precast slab, the effect of the reinforcement near the lifting point was also investigated. From this study, the optimum lifting positions of the precast slabs were determined according to the lifting angle and level, and the results were compared with the lifting positions used in the PCI standards.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.453-461
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• 2014

In this study, the stub columns of built-up H-section and square hollow section subjected to eccentrical loads are tested to evaluate the applicability of the structural members with 800MPa high-strength steel (HSA800) on current design specification. Analytical studies of FE model are conducted to validate the test results and then the verified FE models are used for extensive parametric studies for checking up the applicability of current design code. The parameters are width-to-thickness ratios and axial load ratios. From P-M correlations on parameter models, all stub columns with non-compact sections exceed the current design requirements about axial force and flexural strength ratios are sufficiently secured as the axial load ratios are decreased. The built-up hollow sections with slender section model do not satisfy the current design specification about axial force.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.864-873
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• 2002

Recently, CFT Column has reported a lot of study result, because a CFT column has certain superior structural properties as well as good productivity, execution efficiency, and improved rigidity over existing column. However, CFT column still has problems clearing the capacity evaluation between its steel tube member and high-strength concrete materials. Also, high-strength concrete filled steel square tube column(HCFT) examined numerical value explanatorily about transformation performance(M-ø) of when short-column receives equal flexure-moment from axial stress on research for concrete. hnd, with basis assumption, executed development of analysis program of moment-curvature relation for analytic analysis of transformation performance of HCFT section that get by an experiment. This study investigated to properties of structural(capacity, curvature), through a series of experiments for HCFT with key parameters, such as strength of concrete(600kgf/$\textrm{cm}^2$), D/t ratio, slenderness ratio(λ) and concrete kinds under eccentric load. And, I executed comparative analysis with AISC-LRFD, AIJ and Takanori Sato etc. and experiment result that is capacity design formula.

• Journal of Korean Society of Steel Construction
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• v.29 no.5
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• pp.361-368
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• 2017

ASCE 7-10 defines the torsional irregular structure as the one that has large torsional responses caused by the eccentricity. The code requires that these structures should be designed abide by the torsional provisions. This study evaluates the influence of torsional provisions on the performance of the designed multiple steel moment frames with different eccentricity. In this study, 3D response history analyses are performed. The results show that the moment frame design according to the standard with torsional irregularity provisions showed larger performance as the eccentricity increased and the distribution of plastic hinges similarly to orthopedic structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.195-201
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• 2012

According to many customers' requests, optical measurement module (OMM) applications using automatic measuring devices to measure the machined part rapidly on a machine tool have increased steeply. Touch trigger probes are being used for job setup and feature inspection as automatic measuring devices, and this makes quality checking and machining compensation possible. Therefore, in this study, the use of touch trigger probes for accurate measurement of the machined part has been studied and a macro program for a hole measuring cycle has been developed. This hole is the most common feature to be measured, but conventional methods are still not free from measuring error. In addition, the eccentricity change of the least square circle was simulated according to the roundness error in a hole measurement. To evaluate the reliability of this study, the developed hole-measuring program was executed to measure the hole plate on the machine and verify the roundness error in the eccentricity simulation result.

• Journal of Korean Society of Forest Science
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• v.17 no.1
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• pp.17-22
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• 1973

A study on the wood quality from planted Pinus koraiensis Sieb. et Zucc. has been undertaken by the University Forest in order to gain results of the gross structural features of stem. For this study some groups of trees were felled and several characteristics such as the degree of stem, slenderness, eccentric growth, heartwood diameter, height of butt sweep and butt-swell were analyzed. The results of the study are as follows. 1) The relation between diameter of log and its height in sample trees are nearly parallel to each other. But their degrees of slenderness in logs cut from intermediate and codominant trees are some what gentle as compared with that of logs from dominant tree. 2) The eccentric growth at transverse section of sample trees is generally decreased with the increase of tree height on all sample trees. 3) On the eccentric growth at transverse section of tree, a rather distinct tendency was noticed that all of sample trees showed the direction of eccentric growth in $R_2$ side. 4) Heartwood diameter appeares to become larger as tree growth decrease under same diameter of logs and log diameter in which heartwood appeares is larger in rapid growth rate trees. 5) The maximum height of butt-sweep generally shows that the larger the breast height diameter of tree is, the smaller its height becomes. On the contrary it was noticed that the larger the breast height diameter of trees, the higher the maximum height of butt-swell became. The direction of butt-sweep and butt-swell were shown in $R_1$ side in all sample trees.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.429-435
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• 2012

An abrasion due to continuous friction between a work roll and strip causes the mass of the work roll to be unbalanced in the rolling process. We developed a mathematical model for the rolling mill considering the unbalanced mass and verified the model experimentally. The work roll was approximated as a rigid rotor with eccentricity, and the effect of the unbalanced mass on chatter vibration was investigated. The joint forces computed by quasistatic analysis were applied to the work roll in the rolling mill. Transient responses were obtained, and frequency analysis was performed by solving equations of motion using a direct integration method. Horizontal vibrations were more strongly affected by eccentricity than vertical vibrations. In the horizontal direction, a small eccentricity of 1% of the work roll radius considerably increased the amplitude of the chatter frequency.