• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1919-1925
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• 2001

Overhead cranes consist of trolley, girder, rope, objects, trolley motor, girder motor, and hoist motor. If objects are regarded as mass point, and the acceleration of hoisting motion for objects is neglected, analytical model of overhead cranes becomes a nonlinear model because the length of a rope changes. Equations of motion this model is derived of simultaneous differential equations fur motors and object. Positions of the model are controlled by optimal inputs which obtain from a nonlinear optimal control method. From the results of computer simulation, even if initial states of objects suing, it is founded that position of overhead cranes is controlled, and that swing of objects is suppressed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.655-664
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• 2009

This paper, Part 1, describes the effective dual-input PSS parameter design procedure for the IEEE Type PSS2A against the Dangjin 612 MVA thermal plant's EX2000 excitation system. The suggested tuning technique used the model-based PSS tuning method and consisted of three steps: 1) generation system modeling; 2) determination of PSS2A model parameters using linear, time-domain transient and 3-phase simultaneous analyses, and 3) field testing and verification, which are described in Part 2. The effective PSS2A model parameters of EX2000 system in the Dangjin T/P #4 were designed according to the suggested procedure, and verified by using three analyses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.157-165
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• 2002

Nonlinear analysis of the reinforced concrete beam subjected to torsion is presented. Seventeen equations involving seventeen variables are derived from the equilibrium equation, compatibility equation, and the material constitutive laws to solve the torsion problem. Newton method was used to solve the nonlinear simultaneous equations and efficient algorithms are proposed. Present model covers the behavior of reinforced concrete beam under pure torsion from service load range to ultimate stage. Tensile resistance of concrete after cracking is appropriately considered. The softened concrete truss model and the average stress-strain relations of concrete and steel are used. To verify the validity of present model, the nominal torsional moment strengths according to ACI-99 code and the ultimate torsional moment by present model are compared to experimental torsional strengths of 55 test specimens found in literature. The ultimate torsional moment strengths by the present model show good results.

• Wind and Structures
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• v.4 no.4
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• pp.279-298
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• 2001

The greatest suction on the cladding of flat roof low-rise buildings is known to occur beneath the conical vortices that form along the roof edges for cornering winds. In a companion paper, a model of the vortex flow mechanism has been developed which can be used to connect the surface pressure beneath the vortex to adjacent flow conditions. The flow model is experimentally validated in this paper using simultaneous velocity and surface pressure measurement on a 1 : 50 model of the Texas Tech University experimental building in a wind tunnel simulated atmospheric boundary layer. Flow visualization gives further insight into the nature of peak suction events. The flow model is shown to account for the increase in suction towards the roof corner as well as the presence of the highest suction at wind angles of $60^{\circ}$. It includes a parameter describing vortex suction strength, which is shown to be related to the nature of the reattachment, and also suggests how different components of upstream turbulence could influence the surface pressure.

• Journal of Power Electronics
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• v.19 no.2
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• pp.497-508
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• 2019

The predictive speed control (PSC) strategy can realize the simultaneous control of speed and current by using one cost function. As a model-based control method, the performance of the PSC is vulnerable to model mismatches such as load torque disturbances and parameter uncertainties. To solve this problem, this paper presents a robust predictive speed control (RPSC) strategy for surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed RPSC uses extended state observers (ESOs) to estimate the lumped disturbances caused by load torque changes and parameter mismatches. The observer-based prediction model is then compensated by using the estimated disturbances. The introduction of ESOs can achieve robustness against predictive model uncertainties. In addition, a modified cost function is designed to further suppress load torque disturbances. The performance of the proposed RPSC scheme has been corroborated by experimental results under the condition of load torque changes and parameter mismatches.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.26 no.3
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• pp.156-184
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• 2022

In this article, we propose a novel variational model for restoring color images corrupted by mixed multiplicative Gamma noise and additive Gaussian noise. The model involves a data-fidelity term that characterizes the mixed noise as an infimal convolution of two noise distributions and the saturation-value total variation (SVTV) regularization. The data-fidelity term facilitates suitable separation of the multiplicative Gamma and Gaussian noise components, promoting simultaneous elimination of the mixed noise. Furthermore, the SVTV regularization enables adequate denoising of homogeneous regions, while maintaining edges and details and diminishing the color artifacts induced by noise. To solve the proposed nonconvex model, we exploit an alternating minimization approach, and then the alternating direction method of multipliers is adopted for solving subproblems. This contributes to an efficient iterative algorithm. The experimental results demonstrate the superior performance of the proposed model compared to other existing or related models, with regard to visual inspection and image quality measurements.

• Journal of Korean Society of Transportation
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• v.9 no.2
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• pp.121-126
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• 1991

Wilson made an importent contribution to develop a trip distribution model with the general form of gravity model which is an entropy maximization program. Also Wilson suggested a technique which is called the "iterative balancing method" for soving the model. This te-chnique however is not stable to find solution because it is a heuristic method and sometimes does not converge to the correct solution. In this paper a new solution method using a numerical method for solving the non-linear simultaneous equation system is developed and evaluated in both computers VAX 8700 and PC/AT 286 The result of this method and Wilson's method are compared with each other. Wilson's method resulted in inferior solutions measured by the final norm of residuals.

• Korean Journal of Environmental Biology
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• v.26 no.1
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• pp.1-7
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• 2008

A mathematical model for the synergistic interaction of physical and chemical environmental agents was suggested for quantitative prediction of irreversibly damaged cells after combined exposures. The model took into account the synergistic interaction of agents and was based on the supposition that additional effective damages responsible for the synergy are irreversible and originated from an interaction of ineffective sublesions. The experimental results regarding the irreversible component of radiation damage of diploid yeast cells simultaneous exposed to heat with ionizing radiation ($^{60}Co$) or UV light (254 nm) are presented. It was shown that the cell ability of the liquid holding recovery decreased with an increase in the temperature, at which the exposure was occurred. A good correspondence between experimental results and model prediction was demonstrated. The importance of the results obtained for the interpretation of the mechanism of synergistic interaction of various environmental factors is discussed.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.610-614
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• 2002

Time-mean and absolute geostrophic velocities of the Kuroshio current south of Japan are derived from TOPEX/Poseidon altimeter data using a Gaussian jet model. When compared with simultaneous measurements from a shipboard acoustic Doppler current profiler (ADCP) at two intersection points, the altimetric and ADCP absolute velocities correlate well with the correlation of 0.55 to 0.74. The time-mean velocity is accurate to 1 cm s$^{-1}$ to 5 cm s$^{-1}$. The errors in the absolute and the mean velocities are similar to those reported previously far other currents. The comparable performance suggests the Gaussian jet model is a promising methodology for determining absolute geostrophic velocities, noting that in this region the Kuroshio does not meander sufficiently, which provides unfavorable environment for the performance of the Gaussian jet model.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.6
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• pp.839-846
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• 2013

In this paper, an effort has been made to design and develop an optimized programming model for Real-time Ship Management System. Replacing the conventional interrupt-driven programming model, an embedded real-time operating system (RTOS) has been implemented on the system, allowing processes to run virtually simultaneous and multitasking. Data management algorithms are designed and developed in the RTOS to facilitate data distribution amongst tasks and optimize the CPU processing time through intelligent resource utilization. Finally, data lost in the system has been minimized via the improvement of data processing rate under the optimized programming model.