• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.136-145
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• 2009

This paper proposes control methods and simulation models of a driving system, which consists of converters and inverters, for high speed trains employing multi-level power converters. The control method of a single phase three-level converter for high-speed trains is designed to use DC values instead of instantaneous current values which are usually used in single-phase application, so that it results in a fast and robust voltage control response. In addition, simulation models of Space Vector Pulse Width Modulation (SVPWM) for single phase three-level converters as well as three level inverters are proposed. Experimental results demonstrate the validity of the simulation model for three-level inverters.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.1
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• pp.17-21
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• 2016

This paper investigates the importance of the computational overhead when machine learning methods, such as SVM, LASSO, AdaBoosting and AdaBagging, are used for automatic security classification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1433-1434
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.185-186
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• 2007

• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.444-454
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• 2005

Recently, the requirements of multi-resolution models of a solid model, which represent an object at multiple levels of feature detail, are increasing for engineering tasks such as analysis, network-based collaborative design, and virtual prototyping and manufacturing. The research on this area has focused on several topics: topological frameworks for representing multi-resolution solid models, criteria for the level of detail (LOD), and generation of valid models after rearrangement of features. As a solution to the feature rearrangement problem, the new concept of the effective zone of a feature is introduced in the former part of the paper. In this paper, we propose a feature-based non-manifold modeling system to provide multi-resolution models of a feature-based solid or non-manifold model on the basis of the effective feature zones. To facilitate the implementation, we introduce the class of the multi-resolution feature whose attributes contain all necessary information to build a multi-resolution solid model and extract LOD models from it. In addition, two methods are introduced to accelerate the extraction of LOD models from the multi-resolution modeling database: the one is using an NMT model, known as a merged set, to represent multi-resolution models, and the other is storing differences between adjacent LOD models to accelerate the transition to the other LOD. We also suggest the volume of the feature, regardless of feature type, as a criterion for the LOD. This criterion can be used in a wide range of applications, since there is no distinction between additive and subtractive features unlike the previous method.

• Human Ecology Research
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• v.57 no.3
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• pp.341-352
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• 2019

This study examined the effect of maternal positive parenting attitudes on school adjustment among multi-cultural adolescents in Korea and investigated if multi-cultural adolescents' ego-resiliency mediates the relationship between maternal positive parenting attitudes and school adjustment. We used panel data from the fifth wave (2015) of the Multicultural Adolescents Panel Study (MAPS) collected by the National Youth Policy Institute. Participants were 1,297 multi-cultural adolescents (639 boys, 658 girls) who are second-year middle school students and have foreign mothers. SPSS 25.0 performed descriptive statistical analysis and correlation analysis. The structural equation model (SEM) was estimated with Mplus 5.12. The results of this study were as follows. First, a higher level of maternal positive parenting attitudes were related to higher level of ego-resiliency and school adjustment for multi-cultural adolescents. Second, maternal positive parenting attitudes had an indirect effect on school adjustment for multi-cultural adolescents via ego-resiliency. The results of this study indicate that maternal positive parenting behaviors would help improve the school adjustment of multi-cultural adolescents by increasing the level of ego-resiliency. In addition, the results of this study suggest that improving ego-resiliency for multi-cultural adolescents can be an effective method to help in school adjustment, as well as education for maternal parenting attitude.

• Journal of Distribution Research
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• v.15 no.1
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• pp.25-47
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• 2010

CS is one of the major concerns of managers in the world because it is well known to be a key medium construct for firms' superior outcome. One of the major agents for CS management is retailers. Firms try to manage not only employees but also retailers to promote CS behaviors. And so diverse incentives are used to promote their CS behaviors under diverse channel setting such as multi-channel. However in spite of the rising needs there has been scarce studies on the optimal incentive structure for a manufacturer to offer competing retailers at the multi-channel. In this paper, we try to find better way for a manufacturer to promote the competing retailers' CS behaviors. We investigated how to promote the retailers' CS behavior via game-theoretic modeling. Especially, we focus on the possible incentive, CS bonus type reward introduced in the studies of Hauser, Simester, and Wernerfelt(1994) and Chu and Desai(1995). We build up a multi stage complete information game and derive a subgame perfect equilibrium using backward induction. Stages of the game are as following. (Stage 1) Manufacturer sets wholesale price(w) and CS bonus($\eta$). (Stage 2) Both retailers in competition set CS effort level($e_i$) and retail price($p_i$) simultaneously. (Stage 3) Consumers make purchasing decisions based on the manufacturer's initial reputation and retailers' CS efforts.

• Land and Housing Review
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• v.4 no.4
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• pp.349-360
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• 2013

Recently new town development projects are increasing including more than one local government such as provincial government new town and Wirye new town. Institution improvement for the development and management of complex boundary new town is necessary because present urban development institution is based on the new town of single local government. The concept of multi-level governance provide good conceptual frame in recognizing conflict issues and searching for a collaborative solution in Wirye new town. The purpose of this study is recognizing the conflict issues in the process of development and management and providing the collaborative management method using the conceptual frame of multi-level governance in Wirye new town. For this, we did interviews for the related persons and experts, reference research and professional forum. We drew some implications from the references about urban development and similar cases such as free economic zones. The main results of this study is as in the following. First, we categorised the main conflicts in the development and management in Wirye into 4 sectors, such school, administrative service, utility facilities and urban infrastructures. Then, we analysed the conflict issues of each categories and composed a conflict-structure of Wirye new town. Second, the structure of conflict in Wirye new town is composed of the confrontations between separated management and integrated management and between wide area management and local management. Third, for the cooperative management of Wiyre, we should construct multi-level governance in three dimensions of administrative council, local government association, and special management organization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1693-1713
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• 2018

An important technique used by database administrators (DBAs) is to improve performance in decision-support workloads associated with a Star schema is multi-level partitioning. Queries will then benefit from performance improvements via partition elimination, due to constraints on queries expressed on the dimension tables. As the task of multi-level partitioning can be overwhelming for a DBA we are proposing a wizard that facilitates the task by calculating a partitioning scheme for a particular workload. The system resides completely on a client and interacts with the costing estimation subsystem of the query optimizer via an API over the network, thereby eliminating any need to make changes to the optimizer. In addition, since only cost estimates are needed the wizard overhead is very low. By using a greedy algorithm for search space enumeration over the query predicates in the workload the wizard is efficient with worst-case polynomial complexity. The technology proposed can be applied to any clustering or partitioning scheme in any database management system that provides an interface to the query optimizer. Applied to the Teradata database the technology provides recommendations that outperform a human expert's solution as measured by the total execution time of the workload. We also demonstrate the scalability of our approach when the fact table (and workload) size increases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3208-3229
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• 2017

Rectification is an essential procedure for simplifying the disparity extraction of stereo matching algorithms by removing vertical mismatches between left and right images. To support real-time stereo matching, studies have introduced several look-up table (LUT)- and computational logic (CL)-based rectification approaches. However, to support high-resolution images, the LUT-based approach requires considerable memory resources, and the CL-based approach requires numerous hardware resources for its circuit implementation. Thus, this paper proposes a multi-level accumulation-based rectification method as a simple CL-based method and its circuit implementation. The proposed method, which includes distortion correction, reduces addition operations by 29%, and removes multiplication operations by replacing the complex matrix computations and high-degree polynomial calculations of the conventional rectification with simple multi-level accumulations. The proposed rectification circuit can rectify $1,280{\times}720$ stereo images at a frame rate of 135 fps at a clock frequency of 125 MHz. Because the circuit is fully pipelined, it continuously generates a pair of left and right rectified pixels every cycle after 13-cycle latency plus initial image buffering time. Experimental results show that the proposed method requires significantly fewer hardware resources than the conventional method while the differences between the results of the proposed and conventional full rectifications are negligible.