• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.302-310
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• 2002

This paper presents an application of a improved branch exchange (IBE) algorithm with a tie branch power (TBP) flow equation to solve the Optimal Routing problem for operation of a radial Power system including power distribution system. The main objective of the Optimal Routing problem usually is to minimize the network real power loss and to improve the voltage profile in the network. The new BE algorithm adopts newly designed methods which are composed by decision method of maximum loss reduction and new index of loss exchange in loop network Thus, the proposed algorithm in this paper can search the optimal topological structures of distribution feeders by changing the open/closed states of the sectionalizing and tie switches. The proposed algorithm has been evaluated with the practical IEEE 32, 69 bus test systems and KEPCO 148 bus test system to show favorable performance gained.

• Journal of Ship and Ocean Technology
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• v.9 no.1
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• pp.47-63
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• 2005

In the present study, we suggest a new method for designing complex ship hull forms with multiple domain B-spline surfaces accounting for their topological arrangement, where all subdomains are fully defined in terms of form parameters, e.g., positional, differential and integral descriptors. For the construction of complex hull forms, free-form elementary models such as forebody, afterbody and bulbs are united by Boolean operation and blending surfaces in compliance with the sectional area curve (SAC) of the whole ship. This new design process in this paper is called Sectional Area Curve-Balanced Parametric Design (SAC-BPD).

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.34-37
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• 2001

Park et al. [Proc. KFIS Fall Conf. 10(2) (2000), 59-62] defined fuzzy ${\gamma}$-open sets by using an operation ${\gamma}$ on a fts (X, $\tau$) and investigated the related fuzzy topological properties of the associated fuzzy topology $\tau$/seb ${\gamma}$/ and $\tau$. As generalizations of the notion of fuzzy ${\gamma}$-closed sets, we define gf. ${\gamma}$-closed sets and g*f. ${\gamma}$-closed sets and study basic properties of these sets relative to union and intersection. Also, we introduce and study two classes of ftss called fuzzy ${\gamma}$-T* and fuzzy ${\gamma}$-T$_{1}$2/ spaces by using the notions of gf. ${\gamma}$-closed and g*f. ${\gamma}$-closed sets.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.spc1
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• pp.108-118
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• 2024

As shared electric kick scooters spread to cities worldwide as a result of the proliferation of personal mobility, they have emerged as a significant social issue, impacting pedestrian and user safety, as well as urban aesthetics. In this study, we propose solutions to the unique problems associated with shared electric kick scooters, such as illegal parking, charging, and redistribution. Furthermore, we present research on supplementary services utilizing electric kick scooters in urban areas to enhance citizen safety and user satisfaction through the development of an autonomous electric kick scooter system structure and operational strategies. We suggest a low-cost autonomous electric kick scooter structure and propose AI processing, sensor fusion, and system operation methods to add autonomous capabilities to affordable electric kick scooters. Additionally, we propose operational systems and related technologies for offering various supplementary services.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.3
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• pp.12-36
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• 2023

Graph databases, which store different types of data and their relationships modeled as a graph, can be effective in managing and analyzing real estate spatial data linked by complex relationships. However, they are not widely used due to the limited spatial functionalities of graph databases. In this study, we propose a uniform grid-based real estate spatial data management approach using a graph database to respond to various real estate-related spatial questions. By analyzing the real estate community to identify relevant data and utilizing national point numbers as unit grids, we construct a graph schema that linking diverse real estate data, and create a test database. After building a test database, we tested basic topological relationships and spatial functions using the Jackpine benchmark, and further conducted query tests based on various scenarios to verify the appropriateness of the proposed method. The results show that the proposed method successfully executed 25 out of 29 spatial topological relationships and spatial functions, and achieved about 97% accuracy for the 25 functions and 15 scenarios. The significance of this study lies in proposing an efficient data integration method that can respond to real estate-related spatial questions, considering the limited spatial operation capabilities of graph databases. However, there are limitations such as the creation of incorrect spatial topological relationships due to the use of grid-based indexes and inefficiency of queries due to list comparisons, which need to be improved in follow-up studies.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.75-81
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• 2017

This paper presents a design and parallel control strategy of 1.8 kW low-voltage DC-DC converter (LDC) for mild hybrid electric vehicles to improve their power density, system efficiency, and operation stability. Topology and control scheme are important on the LDC for mild hybrid electric vehicles to achieve high system efficiency and power density because of their very low voltage and large current in input and output terminals. Therefore, the optimal topological structure and control algorithm are examined, and a detailed design methodology for the power and control stages is presented. A working sample of 1.8 kW LDC is designed and implemented by applying the adopted topology and control strategy. Experimental results indicate 92.45% of the maximum efficiency and 560 W/l of power density.

• Convergence Security Journal
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• v.10 no.3
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• pp.29-41
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• 2010

Survelliance and Reconnaissance Sensor Network(SRSN) which can collect various tactical information within battlefield in real time plays an important role in NCW environment, of sensor to shooter architecture. However, due to the resource-limited characteristics of sensor nodes and the intrinsic attributes of sensor network such as wireless communication, the SRSN may be vulnerable to various attacks compared to traditional networks. Therefore, in this paper, we propose a new group key management scheme to guarantee confidentiality, integrity, availability, and authentication during the operation of the SRSN. Proposed scheme generates and distributes the group key based on the topological characteristic of the SRSN and the probabilistic key sharing. The communication cost for distributing the group key is O(logn).

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.588-595
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• 2003

High resolution panchromatic satellite images collected by sensors such as IRS-1C/D and KOMPSAT-1 have a spatial resolution of approximately 6 ${\times}$ 6 ㎡, making them very attractive for urban applications. However, the spectral information present in these images is very limited. In order to overcome this limitation, an object-oriented classification approach is used to identify basic land cover types in urban areas. Before an image can be classified it is segmented at different aggregation levels using a multiresolution segmentation approach. In the course of this segmentation various statistical as well as topological information is collected for each segment. Based on this information it is possible to classify image objects and to arrive at much better results than by looking only at single pixels. Using an image recorded by KOMPSAT-1 over the City of Vienna a land cover classification was carried out for two areas. One was used to set up the rules for the different land cover types. The second subset was classified based on these rules, only adjusting some of the functions governing the classification process.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.384-387
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• 1999

In this paper, we have proposed a testing methodology for Speed-Independent asynchronous control circuits using the self-checking property where the circuit detects certain classes of faults during normal operation. To exploit self-checking properties of Speed-Independent circuits, the Proposed methodology generates tests from the specification of the target circuit which describes the behavior of the circuit. The generated tests are applied to a fault-free and a faulty circuit, and target faults can be detected by the comparison of the outputs of the both circuits. For the purpose of efficient comparison, reachability information of the both circuits in the form of BDD's is used and operations are conducted by BDD manipulations. The identification for undetectable faults in testing is also used to increase efficiency of the proposed methodology. The proposed identification uses only topological information of the target circuit and reachability information of the good circuit which was generated in the course of preprocess. Experimental results show that high fault coverage is obtained for synthesized Speed-Independent circuits and the use of the identification process decreases the number of tests and execution time.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.33-42
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• 2002

A method of automatic 3D tunnel modeling is proposed. The proposed method used the parametric representation of geometry and a hierarchical and relational data structure. These two bases provide the generalization and extension for 3D tunnel modeling. Especially, these two fundamentals ion the basis iota representing the characteristics of the tunnel structure for analysis. The constant-curvature characteristic is exploited to generate 3D mesh on the tunnel surface. This is attributed to the advantage that any 2D automatic mesh generation algorithm can be applied to 3D mesh modeling.