• Earthquakes and Structures
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• v.10 no.5
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• pp.1111-1123
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• 2016

To study seismic performance of steel frame-bent structure, one specimen with one-tenth scale, three-bay, and five-story was tested under reversed cyclic lateral load. The entire loading process and failure mode were observed, and the seismic performance indexes including hysteretic loops, skeleton curve, ductility, load bearing capacity, drift ratio, energy dissipation capacity and stiffness degradation were analyzed. The results show that the steel frame-bent structure has good seismic performance. And the ductility and the energy dissipation capacity were good, the hysteresis loops were in spindle shape, which shape were full and had larger area. The ultimate elastic-plastic drift ratio is larger than the limit value specified by seismic code, showing the high capacity of collapse resistance. It can be helpful to design this kind of structure in high-risk seismic zone.

• Structural Engineering and Mechanics
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• v.15 no.3
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• pp.345-365
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• 2003

The adoption of fibre reinforced polymer (FRP) rebars (whose behaviour is elastic-brittle) in reinforced concrete (RC) cross sections requires the assessment of the influence of time-dependent behaviour of concrete on the load-carrying capacity of these sections. This paper presents a method of computing the load-carrying capacity of sections that are at first submitted to a constant long-term service load and then overloaded up to ultimate load. The method solves first a non-linear visco-elastic problem, and then a non-linear instantaneous analysis up to ultimate load that takes into account the self-equilibrated stress distribution previously computed. This method is then adopted to perform a parametric analysis that shows that creep and shrinkage of concrete increase the load-carrying capacity of the cross section reinforced with FRP and allows for the suggestion of simple design rules.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.208-218
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• 1996

Performance of a VM heat pump is considerably affected by various losses, such as enthalpy dump, reheat loss, pumping loss, conduction loss and shuttle loss. A second-order analysis model of VM heat pumps, which allows consideration of the major losses, was presented. Actual heat transfer rates for heat exchangers were calculated from the heat transfer rates obtained by the adiabatic analysis and various losses. New effective temperatures of heat exchangers were calculated from the actual heat transfer rates and the mean heat transfer coefficients until there was no appreciable change in the effective temperatures. Effects of design parameters, such as phase angle, swept volume ratio, regenerator length and speed on heating capacity, cooling capacity and COP were shown.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.185-194
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• 2004

To evaluate seismic performance of reinforced concrete piers two procedures for capacity spectrum method are presented. The capacity spectrum procedures include the reduction factor-ductility-period($R_{\mu}-{\mu}-T$)relationship in order to construct the inelastic demand spectra from the elastic demand spectra. Application of the procedures are illustrated by example analysis. Maximum displacements estimated by the procedures are compared to those by inelastic time history analysis for several artificial earthquakes. The results show that the maximum displacements estimated by the procedures are, on overall, smaller than those by the inelastic time history analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1369-1376
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• 2005

In case of the drainage type tunnel, the residual water pressure is likely to act on the tunnel lining due to the decrease of water-passing capacity of the filter material. Therefore, this study discussions a method to predict the lining load with the consideration of water passing capacity of the filter material through the literature review and numerical analysis. It is expected from the results of case studies that the design load acting on the concrete lining in the drainage type tunnel could be assumed to be about 50% of the hydrostatic water pressure in steady-state ground-water condition.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.220-225
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• 1993

This paper is an experimental study on shear capacity of the high strength lightweight reinforced concrete beams with shear-depth ratio between 1.5 and 2.5. Thirteen T & rectangular beams were tested to determine their diagonal cracking and ultimate shear capacity. The major variables are shear span-depth ratio (a/d=1.5, 2.0, 2.5), concrete compressive strength(f'c=210, 24., 270㎏/㎠) and tensile steel ratio( =0.6, 1.2%). Based on results obtained from experiment of high strength lightweight reinforced concrete Beam & normal concrete, the following conclusions were drawn. (1) The shear capacity of high-strength lightweight concrete is less 15% than that of normal concrete under same condition. (2) As the results of Comparing this experimental datas with other various formulas. It is regarded that ACI 318-89 shear strength formula related tensile strength is proper to design formula of shear strength of high-strength lightweight reinforced concrete using lightweight concrete.

• Steel and Composite Structures
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• v.25 no.4
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• pp.473-484
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• 2017

In this study a seismic retrofit scheme for a building structure was presented using steel plate slit dampers. The energy dissipation capacity of the slit damper used in the retrofit was verified by cyclic loading test. Genetic algorithm was applied to find out the optimum locations of the slit dampers satisfying the target displacement. The seismic retrofit of the model structure using the slit dampers was compared with the retrofit with enlarging shear walls. A simple damper distribution method was proposed using the capacity spectrum method along with the damper distribution pattern proportional to the inter-story drifts. The validity of the simple story-wise damper distribution procedure was verified by comparing the results of genetic algorithm. It was observed that the capacity-spectrum method combined with the simple damper distribution pattern leaded to satisfactory story-wise distribution of dampers compatible with the optimum solution obtained from genetic algorithm.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.9
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• pp.622-629
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• 2004

In practical control systems, the capacity of actuators is limited and this degrades the system performances and it is often a source of instability. To use full capacity of actuators, we adopt the gain scheduled control permitting the over saturation in controls. The basic idea of gain scheduled control is to use a higher gain control when the state variables are smaller and a lower gain control when the state variables are larger. First, we derive a constant H control and a reachable set while satisfying the degree of over saturation. Next, we divide this set into nested subsets and find $H_{\infty}$ controls at rack subsets while satisfying the degree of over saturation. Finally, the control gain is applied according to the status of states. Note that all procedures are done by solving linear matrix inequalities(LMI). Finally, we show the validity and applicability of our proposed control using the simulations of a six-story building subjected to the earthquake excitation.

• 유체기계공업학회:학술대회논문집
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• 1998.02a
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• pp.3-10
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• 1998

The situation frequently occurs in which the input torque capacity of the converter should be changed. It is known that the modification of the ou angles of the torque converter elements is suitable for such situation with diameter of flow path of the converter maintained. But so far it has been, predict correctly the converter characteristics as well as the effects of oulet torque capacity in the past numerical methods. In the present numeric introducing the interrow mixing planes, the torque capacity was satifactorily and it was shown that the torque capacity could be effectively changed by the oulet blade angles of pump and stator.

• Journal of Power System Engineering
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• v.22 no.1
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• pp.87-93
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• 2018

Specimens were machined out from hot-rolled AZ31 magnesium alloy, and deformed at 623K with rolling reduction of 30%. After hot rolling, specimens were annealed at various range of temperature and time. In this study, static recrystallization was occurred during heat treatment, however, variation of main component and intensity of texture was not revealed. The results of microstructure observation, damping capacity test and dislocation mechanism indicated that increasing of damping capacity was caused by grain growth. It means that grain size is effective factor to damping capacity.