• Journal of Electrical Engineering and Technology
• /
• v.10 no.2
• /
• pp.465-473
• /
• 2015

The increasing need to improve transient security assessment of existing or forecasted operating conditions of networks by power system operators is major concern of the power system security monitoring problem at the Energy Management Systems. This paper proposes a preventive control of transient stability with generation rescheduling based on rotor trajectory index obtained using time domain simulations. This index may help power engineers in making operational decision and to obtain a generation configuration with better transient security dispatch. The effectiveness of the proposed methodology is demonstrated on IEEE 39-bus New England system for a three phase fault at different loading conditions with single and multiple line outage cases.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.5
• /
• pp.1983-1988
• /
• 2015

This paper proposes the enhanced application of superconducting magnetic energy storage (SMES) for the effective compensation of power fluctuations based on the interleaving technique. With increases in demand for renewable energy based photovoltaic (PV) generation system, the output power fluctuations from PV generation system due to sudden changes in environmental conditions can cause serious problems such as grid voltage and frequency variations. To solve this problem, the SMES system is applied with its superior characteristics with respect to high power density, fast response for charge and discharge operations, system efficiency, etc. In particular, the compensation capability is effectively improved by the proposed interleaving technique based on its parallel structure. The dynamic performance of the system designed using the proposed method is evaluated with several case studies through time-domain simulations.

• Journal of the Korean Society of Industry Convergence
• /
• v.11 no.2
• /
• pp.83-91
• /
• 2008

GMAW(Gas Metal Arc Welding) processes are usually used in industrial side in order to get its high productivity. But those are only adopted in the semi-automated welding equipment because of a lot of welding spatters. Many industrial robot actually percents from being engaged in the welding processes. The welding spatter problem of causes blocking them being a fully automated welding process.This study was carried out to investigate the optimal conditions for minimizing welding spatter generation at GMAW robot. The spatter can be significantly reduced below 2% of welding spatter generation at the following conditions ; First, below 18V at the wire-feed rate 2.0mm/min Second, below 23V at the wire-feed rate 3.6mm/min Third, below 24V at the wire-feed rate 5.5mm/min.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.1 no.2
• /
• pp.64-72
• /
• 2006

The long propagation delay over satellite internet causes degradation of TCP performance in slow start phase. Especially, web traffic performance is greatly reduced by low throughput in slow start phase. To improve web traffic performance, we propose the Dynamic ACK Generation Scheme which generates ACKs and considers sender RTO in PEP (Performance Enhancing Proxy). The Normal ACK generation mechanism improves TCP throughput, and also decreases sender RTO. if PEP stops generating ACKs, TCP performance will be reduced by frequent RTO expiration. To solve this problem, our scheme adjusts RTO using ACK generation interval. And it supports retransmission mechanism for loss recovery in PEP. The results of the performance analysis provide a good evidence to demonstrate the efficiency of our mechanisms over satellite internet.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.12
• /
• pp.603-610
• /
• 2002

In this paper, a new economic dispatch algorithm for unit commitment is proposed to improve both the accuracy of the final solution and the calculation speed of economic dispatch. By using the inverse incremental cost functions, economic dispatch can be transformed into a simple optimization problem associated with an n-th order polynomial equation. The proposed method remarkably reduces the computation time with adaptability to any higher order generation cost functions. The proposed method is tested with sample system, which shows that the proposed algorithm yields more accurate and economical generation scheduling results with high computation speed.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.325-332
• /
• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cutting pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.9
• /
• pp.761-773
• /
• 1991

In this paper, an algorithm for automatic schematic generation which creates schematic diagram from netlist are proposed. The important objectives on schematic generation are readability and clarity of resulting schematics. Each stage of generation should aim at enhancing these objectives. For this reason, schematic generation problem is divided into 5 subproblems` preprocessing, logical placement, pin assignment and improvement of placement, global routing, and detailed routing. The algorithm is implemented in C language, and it generates schematics from the results of logic synthesis in order to make it east for designers to understand the design and reflect their knowledge into design.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.1
• /
• pp.213-223
• /
• 2016

The validity of landfill gas models is an important problem considering that they are frequently used for landfill-site-related policy making and energy recovery planning. In this study, the Monte Carlo method was applied to an landfill gas generation model in order to enhance conformity. Results show that the relative mean deviation between measured data and modeled results (MD) decreased from 19.8% to 11.7% after applying the uncertainty range of Intergovernmental Panel on Climate Change (IPCC) to the methane-generation potential and reaction constants. Additionally, when let reaction constant adjust derived errors from all other modeling components, such as model logic, gauging waste, and measured methane data, MD decreased to 6.6% and the disparity in total methane generation quantity to 2.1%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.11
• /
• pp.67-72
• /
• 2011

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, for high efficiency of power generation per natural light unit area is needed to sun tracking system. And it is needed to condensed light generator for reducer of equipment expense. As method of solving this problem, this paper is developed multi-flat reflector sun tracking system for sun photocell maximum power generation. The system is consisted of multi-flat reflector and two axes machinery and sun location perceiver and AVR controller. GaAs 3J cell generated 6.75 times power more than silicon cell by times condensing light system. As a result, condensing light system of multi-flat reflector generated maximum power and showed reducing costs to photovoltaic generator.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.366-368
• /
• 2003

In this paper, a parametric evaluation method of protection ability is proposed. The adequacy of every parameter is evaluated for the setting rules. Then the results are combined to give protection level of a whole protective system. The setting rules are categorized into three groups for hierarchical calculation. The proposed scheme is applied to a location problem of a new protective device to show its effectiveness.