• Korean Journal of Materials Research
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• v.31 no.10
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• pp.586-591
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• 2021

This paper proposes a mathematical model that can calculate the luminescence characteristics driven by alternating current (AC) power using the current-voltage-luminance (I-V-L) properties of organic light emitting devices (OLED) driven by direct current power. Fluorescent OLEDs are manufactured to verify the model, and I-V-L characteristics driven by DC and AC are measured. The current efficiency of DC driven OLED can be divided into three sections. Region 1 is a section where the recombination efficiency increases as the carrier reaches the emission layer in proportion to the increase of the DC voltage. Region 2 is a section in which the maximum luminous efficiency is stably maintained. Region 3 is a section where the luminous efficiency decreases due to excess carriers. Therefore, the fitting equation is derived by dividing the current density and luminance of the DC driven OLED into three regions, and the current density and luminance of the AC driven OLED are calculated from the fitting equation. As a result, the measured and calculated values of the AC driving I-V-L characteristics show deviations of 4.7% for current density, 2.9 % for luminance, and 1.9 % for luminous efficiency.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.59-61
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• 2008

Optimal design of the direct-driven PM Wind Generator, combined with DEAS(Dynamic Encoding Algorithm for Searches) and FEM(Finite Element Method), has been proposed to maximize the Annual Energy Production(AEP) over the whole wind speed characterized by the statistical model of wind speed distribution. In particular, DEAS has been contributed to reducing the excessive computing time for the optimization process.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.552-558
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• 2008

Optimal design of the direct-driven Permanent Magnet(PM) wind generator, combined with F.E.A(Finite Element Analysis) and Genetic Algorithm(GA), has been performed to maximize the Annual Energy Production(AEP) over the entire wind speed characterized by the statistical model of wind speed distribution. Particularly, the proposed parallel computing via internet web service has contributed to reducing excessive computing times for optimization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1093-1098
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• 2004

This paper presents a close-loop feedback control scheme, which can simultaneously satisfy multiple conflicting control performances, for a high speed positioning system driven by a brushless D.C. motor. With the dynamic model of the motor and proportional-plus-derivative feedback controllers selected as sample controllers, the convex combined feedback controller is formulated for implementing a direct-drive manipulator. Experimental results show that the developed multiple simultaneous specification(MSS) controller can meet desired control performances; maximum overshoot and rise time.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.110-117
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• 1998

A continuum-based configuration design sensitivity analysis method is developed for kinematically driven mechanical systems. The configuration design variable for mechanical systems is defined. The 3-1-3 Euler angle is employed as the orientation design variable. Kinematic admissibility conditions of configuration design change. Direct differentiation method is used to derive the governing equations of the design sensitivity. Numerical examples are presented to demonstrate the validity and effectiveness of the proposed method.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.15-19
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• 2014

As the space of the wind power generator stator end is limited, it is difficult for us to place the inner evaporative cooling system in it. We use the non-overlapping concentrated windings scheme to solve the placing and cooling problem. The characteristic of a 5MW direct-driven permanent magnet generator with non-overlapping concentrated windings were analyzed under no-load, rating-load and short-circuit by (Finite Element Method) FEM for verification of design. We studied the connection methods of the stator windings and designed the end connection member. The heat dissipation of the stator end was simulated by FEM, the result showed that the end cooling could satisfy the wind generator operation needs. These results show that the direct-driven permanent magnet wind power generators with non-overlapping concentrated windings and inner evaporative cooling system can solve the cooling problem of wind power generator, and obtain good performance at the same time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.149-156
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• 2010

In this paper, the optimal design of a wind generator, implemented with the hybridized GA(Genetic Algorithm) and ES(Expert System), has been performed to maximize the AEP(Annual Energy Production) over the whole wind speed characterized by the statistical model of wind speed distribution. In particular, to solve the problem of calculation iterate, ES finds the superior individual and apply to initial generation of GA and it makes reduction of search domain. Meanwhile, for effective searching in reduced search domain, it propose Intelligent GA algorithm. Also, it shows the results of optimized model 500[kW] wind generator using hybridized algorithm and benchmark result of compare with GA.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.133-139
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• 2003

Direct motor-driven winding has been increasingly applied in winding machinery. However, it is necessary to analyze the kinematics of winding prior to developing the winding control algorithm, because direct motor-driven winding machine should be operated in accordance with the pre-determined kinematic information for the winding control. This paper presents the kinematics of the degressive winding method and its kinematic winding control algorithm in order to wind the required volume of a pirn package in a desired shape. The proposed algorithm can give the appropriate yarn speed, traverse speed, and the spin speed of the spindle at every traverse stroke, which are utilized for controlling the spindle motor and traverse motor of the winding machine. Computer winding simulations showed that the proposed algorithm is successful in the degressive pirn winding.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.1
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• pp.74-84
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• 1991

This paper presents an algorithm for technology-dependent logic optimization and technology mapping, and describes a performance-driven logic synthesis system, SILOS, implemented based on the proposed algorithm. The system analyzes circuits and resynthesizes the critical sections such that generated circuit operates opertes within time constraints, using only gate types supported by library for direct implementation. Experimental results show that the system can be a viable tool in synthesizing high-performance logic circuits.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.11 no.1
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• pp.12-20
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• 2006