• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.153-154
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• 2008

This paper presents a window-based software package for the education and training for the reduction of power system by using locational marginal price (LMP), clustering, and similarity indices of each bus. The developed package consists of three modules: 1) the LMP module, 2) the Clustering module and 3) the Reduction module. Each module has a separated and interactive interface window. First of all, LMPs are created in the LMP module, and then the Clustering module carries out clustering based on the results of the LMP module. Finally, groups created in this Clustering module are reduced by using the similarity indices of each bus. The developed package displays a variety of tables for results of the LMPs of base network, voltages, phases and power flow of reduced network so that the user can easily understand the reduction of network. To demonstrate the performance of the developed package, it is tested for the IEEE 39-bus power system.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.382-388
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• 2017

In response to the global warming crisis, the Kyoto protocol was established by major developed countries in 1997. The Paris Agreement, which imposes a carbon reduction obligation for both developed countries and developing countries, was signed in 2015. Regulations and efforts to reduce greenhouse gas emissions accordingly have been implemented. In this study, we analyzed the reduction of carbon emissions computerizing of the traditional project management system for efficient railway construction at Korea Rail Network Authority. We suggest a model that measures two major effects of carbon reduction, stemming from transportation and from a decrease of paper use. In this paper, we calculate the amount of carbon reduction and the economic effect of carbon reduction with application of the construction project management system at Korea Rail Network Authority. The model and methodology in this study are expected to be helpful to measure the carbon reduction performance for similar e-transformation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.153-165
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• 2006

A damage in a structure changes its dynamic characteristics such as natural frequencies, damping ratios, and the mode shapes. In this paper the effort has been spent in obtaining the characteristics of the reduction ratio in natural frequencies and the damage detection is performed using the reduction ratios. Most of the emphasis has been on using the artificial neural network to determine the location and the extent of the damage as well as the existence of the damage. The data for learning and verifying neural network were obtained from the analytical analysis. The data have no errors. Considering the real measurements the data including errors which are difference this study between other studies also were used for neural network. The position and extent of the damage can be detected using the neural network trained by reduction ratios of natural frequencies.

• Journal of the Korea Society for Simulation
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• v.5 no.1
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• pp.91-106
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• 1996

Control Variate (CV) is very useful technique for variance reduction in a wide class of queueing network simulations. However, the loss in variance reduction caused by the estimation of the optimum control coefficients is an increasing function of the number of control variables. Therefore, in some situations, it is required to select an optimal set of control variables to maximize the variance reduction . In this paper, we develop the Adaptive Control Variates (ACV) method which selects an optimal set of control variates during the simulation adatively. ACV is useful to maximize the simulation efficiency when we need iterated simulations to find an optimal solution. One such an example is the Simulated Annealing (SA) because, in SA algorithm, we have to repeat in calculating the objective function values at each temperature, The ACV can also be applied to the queueing network optimization problems to find an optimal input parameters (such as service rates) to maximize the throughput rate with a certain cost constraint.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.241-247
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• 2001

Network reconfiguration in distribution systems is realized by changing the status of sectionalizing switches, and is usually done for loss reduction of load balancing in the system. This paper presents an effective heuristic based switching scheme to solve the distribution feeder loss reduction problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to apply a proposed technique called cyclic best first search. the proposed algorithm identify the most effective the set of switch status configuration of distribution system for loss reduction. To demonstrate the validity of the proposed algorithm, numerical calculations are carried out the 32, 69 bus system models.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.686-688
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• 1996

Network reconfiguration is performed by opening/closing two types of switches, tie and sectionalizing switches. A whole feeder, or part of a feeder, may be served from another feeder by closing a tie switch linking the two while an appropriate sectionalizing switch must be opened to maintain radial structures. In loss reduction, the problem is to identify tie and sectionalizing switches that should be closed and opened, respectively, to achieve a maximum loss reduction. In this paper, it is introduced to propose the reconfiguration plan for loss reduction by using the Civanlar's loss reduction formular.

• ETRI Journal
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• v.40 no.3
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• pp.355-365
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• 2018

The increase in data traffic calls for investment in mobile networks; however, the saturating revenue of mobile broadband and increasing capital expenditure are discouraging mobile operators from investing in next-generation mobile networks. Mobile network sharing is a viable solution for operators and regulators to resolve this dilemma. This research uses a difference-in-differences analysis of 33 operators (including 11 control operators) to empirically evaluate the cost reduction effect of mobile network sharing. The results indicate a reduction in overall operating expenditure and short-term capital expenditure by national roaming. This finding implies that future technology and standards development should focus on flexible network operation and maintenance, energy efficiency, and maximizing economies of scale in radio access networks. Furthermore, mobile network sharing will become more viable and relevant in a 5G network deployment as spectrum bands are likely to increase the total cost of ownership of mobile networks and technical enablers will facilitate network sharing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.410-415
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• 2004

The oscillation of the fluid caused by external forces is call ed sloshing, which occurs in moving vehicles with contained liquid masses, such as trucks, railroad cars, aircraft, and liquid rocket. This sloshing effect could be a severe problem in vehicle stability and control. In this study, the optimization design technique for reduction of the sloshing using evolutionary method is suggested. Two evolutionary methods are employed, respectively the artificial neural network(ANN) and genetic algorithm. An artificial neural network is used for the analysis of sloshing and genetic algorithm is adopted as optimization algorithm. As a result of optimization design, the optimized size and location of the baffle is presented

• ETRI Journal
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• v.25 no.6
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• pp.531-534
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• 2003

This report describes the effect of optical delay on the suppression of the power transient excursion in a combined gain-controlled erbium-doped fiber amplifier with an internal optical feedback loop (OFL). A simple homogeneous model showed that the optical delay caused a phase change in the oscillation of the surviving and laser channels, which resulted in a reduction of the overall power transient excursion. In addition to the reduction, a real system with a 1528.7-nm OFL shifted the oscillation upward or downward according to channel removal or addition, whereas another one with a 1560.9-nm OFL did not. This different transient behavior reflected a control-wavelength dependence on optical automatic gain control, where spectral-hole burning dominated over relaxation oscillation for 1528.7 nm, and vice versa for 1560.9 nm.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.11a
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• pp.147-161
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• 1997

In the future, the performance of B-lSDN offering the multimedia and a various service depends on the performance of switch that is the important factor consisting of network. Bufferless banyan network consisted of MIN(multistage interconnection network) selected for- the fabric of ATM switch and has a limitation of performance because of blocking. Input buffered banyan networks with FIFO(first-in first-out) buffering scheme for the reduction of blocking and the cell bypass queueing theory for the reduction of HOL(head of line) blocking were seperately compared of the performance of switch. Specially input buffered banyan networks were applied monotonic buffering scheme that was proposed. As a result of simulation, Buffered Banyan Network with cell bypass queueing theory showed better performance than FIFO type input buffered Banyan network. Monotonic increase buffering scheme showed better performance than Monotonic decrease buffering scheme.