• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.229-231
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• 2000

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2016.09a
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• pp.135-138
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• 2016

• Journal of Korean Society of Transportation
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• v.33 no.2
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• pp.204-213
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• 2015

The congestion of pedestrians impedes the utilization efficiency of a subway station. Conflicts among pedestrians due to unseparated pedestrian flows not only increase the impedance of pedestrian mobility but also negatively affect on pedestrian safety. This paper analyzes the travel characteristics of bi-directional pedestrian flow based on microscopic movements, and evaluates the operation efficiency on separating the traffic line. The subway station was simulated in a 2-D grid structure by applying Discrete Element Method, and the movement is organized in each cell of the grid. As a result, the model explicates that separating the traffic line and encouraging the 'Keep right rule' would be mostly effective for the conflicting flows. Therefore, applying the 'Walking Guidance System' would be efficient to improve the pedestrian convenience and mobility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.9
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• pp.817-824
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• 2010

An improved spray model of a pressure-swirl atomizer was developed and the grid dependency of the model was investigated. Since the Lagrangian-Eulerian approach was adopted for tracking droplets, very small grids could not be used. However, in order to detect swirl flow accurately, small grids were needed because of the consideration of swirl injection. In order to overcome these limitations, numerical studies were performed by using various grids with cell sizes ranging from 10.0 $\times$ 10 mm to 0.625 $\times$ 0.625 mm. From these calculated results, it was observed that the most efficient grid cell size was 1.25 $\times$ 1.25 mm.

• Journal of IKEEE
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• v.24 no.1
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• pp.364-367
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• 2020

This paper presents the off-grid PV-ESS system of sequential voltage control method applied to OR logic gate. The conventional off-grid PV-ESS system with the low-voltage series connection has problems due to capacity expansion. To solve these problems, this paper proposes a noble PV-ESS system with high efficiency and low cost by applying sequential voltage control technique of the high-voltage series connection of analog circuit type. The input voltage of DC to AC inverter can be converted from the low-voltage by the combinations of series connection of the conventional cascaded 24V solar cell unit modules to the high-voltage of 384V in battery. The output voltage of the battery was 384V as the each input voltage of three phase DC to AC inverter, and the each output voltage of three phase 10kW DC to AC inverter is designed to be AC380V@60Hz as the line to line rms voltage value. To prove the validity of the theoretical analysis by PSIM simulation, the operating characteristics of sequential voltage control system with OR logic gate were confirmed through experiment results.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.567-576
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• 2003

Spatial data mining, i.e., discovery of interesting characteristics and patterns that may implicitly exists in spatial databases, is a challenging task due to the huge amounts of spatial data. Clustering algorithms are attractive for the task of class identification in spatial databases. Several methods for spatial clustering have been presented in recent years, but have the following several drawbacks increase costs due to computing distance among objects and process only memory-resident data. In this paper, we propose an efficient grid cell based spatial clustering method for spatial data mining. It focuses on resolving disadvantages of existing clustering algorithms. In details, it aims to reduce cost further for good efficiency on large databases. To do this, we devise a spatial clustering algorithm based on grid ceil structures including cell relationships.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.153-156
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• 2007

This paper presents the design, development and performance of a power conditioning system (PCS) for application to a 250kW Molten Carbonate Fuel Cell (MCFC) generation system. A DSP controller was used to control the dc-dc and dc-ac converter operation for grid connection and power injection to the grid. The controller must also supervise the total PCS operation while communicating with the fuel cell system controller. A control method for parallel operation of dc-dc converters was proposed and verified. A 250kW prototype was successfully built and tested. Experimental performances are compared to minimum target requirements of the PCS for MCFC.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.530-532
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• 2007

This paper presents the design, development and performance of a power conditioning system (PCS) for application to a 250kW Molten Carbonate Fuel Cell (MCFC) generation system. A DSP controller was used to control the dc-dc and dc-ac converter operation for grid connection and power injection to the grid. The controller must also supervise the total PCS operation while communicating with the fuel cell system controller. A control method for parallel operation of dc-dc converters was proposed and verified. A 250kW prototype was successfully built and tested. Experimental performances are compared to minimum target requirements of the PCS for MCFC.

• Journal of Software Assessment and Valuation
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• v.17 no.2
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• pp.151-159
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• 2021

To derive grid lines for analyzing a table layout, line image enhancement techniques are studying such as various filtering or morphology methods. In spite of line image enhancement, it is still hard to extract line components and to express table cell's layout logically in which the cutting points are exist on the line or the tables are skewing . In this paper, we proposed a line tracking algorithm to extract line components under the cutting points on the line or the skewing lines. The table document layout analysis algorithm is prepared by searching grid-lines, line crossing points and gird-cell using line tracking algorithm. Simulation results show that the proposed method derive 96.4% table document analysis result with average 0.41sec processing times.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.127-131
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• 2005

The paper addresses modeling and analysis of a grid-connected photovoltaic generation system (PV system). PSCAD/EMIDC. an industry standard simulation tool for studying the transient behavior of electric power system and apparatus. is used to conduct all aspects of model implementation and to carry out extensive simulation study. An equivalent circuit model of a solar cell has been used for modeling solar array. A PWM voltage source inverter (VSI) and its current control scheme have been implemented. A maximum power point tracking (MPPT) technique is employed for drawing the maximum available energy from the PV array. Comprehensive simulation results are presented to examine PV array behaviors and PV system control performance in response to irradiation changes. In addition, dynamic responses of PV array and system to network fault conditions are simulated and analysed