• Journal of Power Electronics
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• v.19 no.2
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• pp.529-539
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• 2019

The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.177-180
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• 2004

In this study, we report a novel encapsulation method for longevity of an organic thin-film transistor (OTFT) using pentaceneby means of an adhesive multiplayerincluded Al film. For encapsulation of OTFTs, the Al film adhered onto the OTFT in a dry nitrogen atmosphere using a proper adhesive. A lifetime, which was defined as the time necessary to reduce mobility to 2% of initial mobility value, was observed from the typical $I_{D-VD}$ characteristics of the field-effect transistor (FET). The initial field effect mobility ${\mu}$ was measured to be $2.0{\times}10^{-1}\;cm^2/Vs$. The characterization was maintained for long times in air. No substantial degeneration occurred. The performance and the stability are probably due to the encapsulation effect.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.114-117
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• 1998

This paper highlights new IP network design and internetworking scenarios overlayed on the existing ATM technology network. It describes the proper network configurations to solve the IP/ATM internetworking probrems on the AISN(Advanced Information Superhighway Network). The paper outlines that IP network can be constructed on ATM backbone network. The paper looks at how new design technology is to enhance the AISN in Korea. The paper concludes that new IP network design is applied to AISN and there is enough possibility that AISN can be developed to efficient NGI(Next Generation Internet).

• ETRI Journal
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• v.13 no.2
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• pp.34-41
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• 1991

In this paper, a new distributed parallel algorithm for pattern classification based upon Self-Organizing Neural Network(SONN)[10-12] is developed. This system works without any information about the number of clusters or cluster centers. The SONN model showed good performance for finding classification information, cluster centers, the number of salient clusters and membership information. It took a considerable amount of time in the sequential version if the input data set size is very large. Therefore, design of parallel algorithm is desirous. A new distributed parallel algorithm is developed and experimental results are presented.

• Proceedings of the Korea Association of Information Systems Conference
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• 2005.05a
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• pp.79-92
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• 2005

To query the vast amount of web pages which are available i]l the Internet, it is necessary to extract the encoded information in the web pages for converting it into structured data (e.g. relational data for SQL) or semistructured data (e.g. XML data for XQuery), In this paper, we propose a new web information extraction system, PIES, to convert web information into XML documents. PIES is based on a user-specified target schema and HTML tag pattern descriptions. The web information is extracted by the pattern descriptions and validated by the target schema. We designed a new language to describe extraction rules, and a new regular expression to describe HTML tag patterns. We implemented PIES and applied it to the US patent web site to evaluate its correctness. It successfully extracted more than thousands of US patent data and converted them into XML documents.

• Asia pacific journal of information systems
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• v.11 no.4
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• pp.1-25
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• 2001

Manufacturing firms face a paradigm shift from industrial systems driven by efficiency to post-industrial systems where success depends on a quick-response to customer demands for a variety of high-quality products. In essence, time is becoming a critical dimension for competition. New information technologies allow many firms to pursue time-based competitive strategies. The purpose of this research is to investigate the relationship among the types of information technology, behaviors of suppliers, the structures of new product development processes, and the competitiveness of the firms. The data for this study were collected from 96 Korean manufacturing firms that have implemented certain types of information technologies. Research results from LISREL analysis confirm that the competitiveness comes from product innovation capabilities and innovative product development process. But the linkage between the information technologies and the firms' competitiveness proves to be indirect. Suppliers, organizational culture related to IT, and some other factors also have indirect impact on the competitiveness. A summarized report of other findings is provided as well.

• Korean Journal of Human Ecology
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• v.17 no.2
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• pp.279-292
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• 2008

The concept of "new consumer sovereignty" is playing a significant role in having the initiative of production and consumption of technology and culture trend. Today the 'new consumers' positively use digital and information technology in purchasing. To understand these consumers' new purchase tendency, the study examined the actual conditions 1) of consumers' use of digital and information technology, 2) of digital devide between consumers, and 3) the consumer's attitude to changes of their lifestyle which digital convergence could result in. The subjects were thousand male and female adults. The data were collected from a survey conducted by Embrain, a research firm in Seoul, in the period of June 1st, 2007 ${\sim}$ June 10th, 2007. The results show: 1. Most subjects have computers, their Internet use is their general life, and they have lots of exposure opportunities to digital information. They positively and actively use information technology. 2. Between male and female subjects, and between old and young generation there is a significant digital gap. But the gap between regional areas is statistically not significant. 3. The subject's attitude to digital convergence society shows both positive expectation and negative concerns. Concludingly, to embody a desirable digital convergence society, it is necessary to be searched the ways which can decrease the digital gap and policy to share benefit that information technology can give to consumers.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.457-463
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• 2013

In recent days, cooperative diversity and communication security become important research issues for wireless communications. In this paper, to achieve low probability of interception (LPI) and high throughput in the cooperative single-carrier frequency division multiple access (SC-FDMA) system, a new physical layer transmission scheme is proposed, where a new encryption algorithm is applied and adaptive modulation is further considered based on channel state information (CSI). By doing so, neither relay node nor eavesdropper can intercept the information signals transmitted from user terminal (UT). Simulation results show above new physical layer transmission scheme brings in high transmission safety and secrecy rate. Furthermore, by applying adaptive modulation and coding (AMC) technique according to CSI, transmission throughput can be increased significantly. Additionally, low peak-to-average power ratio (PAPR) characteristic can still be remained due to the uniform distribution of random coefficients used for encryption algorithm.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.470-474
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• 2008

A well-designed computer network technology produces benefits on several fields within the organization, between the organizations(suborganizations) or among different organizations(suborganizations). Network technology streamlines business processes, decision process. Graphs are useful data structures capable of efficiently representing a variety of networks in the various fields. Metagraph is a like graph theoretic construct introduced recently by Basu and Blanning in which there is set to set mapping in place of node to node as in a conventional graph structure. Metagraph is thus a new type of data structure occupying its popularity among the computer scientists very fast. Every graph is special case of Metagraph. In this paper the authors introduce the notion of Meta-Networking as a new network technological representation, which is having all the capabilities of crisp network as well as few additional capabilities. It is expected that the notion of meta-networking will have huge applications in due course. This paper will play the role of introducing this new concept to the network technologists and scientists.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.679-682
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• 2003

We report the suitable SLS (sequential lateral solidification) as a function of laser intensity. Precursor film is changed from 50nm to 100nm and is deposited on glass substrate by PECVD. We can find the suitable SLS length by changing the mask size. In this paper, we present the well-defined grain growth conditions as a function of laser intensity.