• Journal of Communications and Networks
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• v.16 no.4
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• pp.371-377
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• 2014

Localized topology control is attractive for obtaining reduced network graphs with desirable features such as sparser connectivity and reduced transmit powers. In this paper, we focus on studying how to prolong network lifetime in the context of localized topology control for wireless multi-hop networks. For this purpose, we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hop neighborhood topology. In order to achieve long network lifetime, we introduce a new metric for characterizing the energy criticality status of each link in the network. Each node independently builds a local energy-efficient spanning tree for finding a reduced neighbor set while maximally avoiding using energy-critical links in its neighborhood for the local spanning tree construction. We present the detailed design description of our algorithm. The computational complexity of the proposed algorithm is deduced to be O(mlog n), where m and n represent the number of links and nodes in a node's one-hop neighborhood, respectively. Simulation results show that our algorithm significantly outperforms existing work in terms of network lifetime.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1570-1578
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• 2000

A quadrature pair of filter banks that are composed of a pair of cosine and sine modulated filter banks is applied to MC-CDMA data transmultiplexing in the view point of mitigating inter-channel interferences. Exploiting superior capabilities of wavelet properties in composing the filter banks the proposed scheme is capable of compromising inter-channel interference problems better than the conventional DFT-based MC-CDMA due to superior subchannelization effects. To verify the behavior of our proposed MC-CDMA system based on the quadrature filter banks the reverse-link bit error rates with respect to signal-to-noise ratio under Rayleigth fading and additive white Gaussian noise channel environments are computed. The results show an improved system performance over the conventional MC-CDMA in the view point of minimizing interference effects.

• Journal of Power Electronics
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• v.3 no.4
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• pp.230-238
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• 2003

Electric vehicles (EV) demands for greater acceleration, performance and vehicle range in pure electric vehicles plus mandated requirements to further reduce emissions in hybrid electric vehicles (HEV) increase the appeal for combined on-board energy storage systems and generators. And the power electronics plays an important role in providing an interface between fuel cells (FC) and loads. This paper deals with a multiple input DC-DC power converter devoted to combine the power flowing of multi-source on energy systems. The multi-source is composed of (i) FC system as a prime power demands, (ii) super capacitor banks as energy storage devices for high and intense power demands, (iii) superconducting magnetic energy storage system (SMES), (iv) multiple input DC-DC power converter and (v) a three phase inverter-fed permanent magnet synchronous motor as a drive. In this system, It is used super capacitor banks and superconducting magnetic energy replaces from the battery system. The modeling and transient performance simulation is effective for reducing transient influence caused by sudden charge of effective load. The main purpose of power electronic converters is to convert the DC power output from the fuel cell and other to a suitable AC voltage, which can be connected to electric loads directly (PMSM). The fuel cell and other output is connected to the DC-DC converter, which regulates the DC link voltage.

• Journal of Korea Planning Association
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• v.54 no.4
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• pp.26-37
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• 2019

It is necessary to implement a wide range of housing welfare policies that citizens can experience in order to improve residents' the quality of life, as it emphasizes the balance of supply and management of public housing. The purpose of this study is to analyze the factors affecting residential satisfaction considering the three hierarchical levels of individual, household, and area. In the background of the study, the individuals' quality-of-life satisfaction determined not only by the individual but also by the various influencing environmental factors. This study targets 1,736 households, 3,239 persons in 464 areas in Seoul. The main research results are as follows. At the level one, there were influencing factors such as age(-), education level and income, and housing area per person, recipient of basic living(-), period(-) and RIR (at the level two). At the level three, west-south region(-) and social mix affect the complex of public housing. In consideration of living infrastructure, the closer to public transportation, public facilities, and medical facilities, the higher the satisfaction of public housing. The results of this analysis suggest that public support needs to focus on individual household members, but there is a need for ways to link it with the complex and the region.

• The KIPS Transactions:PartB
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• v.12B no.1 s.97
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• pp.81-90
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• 2005

In this paper, we propose a novel approach which models multilingual story link detection by adapting the features such as timelines and multilingual spaces as weighting components to give distinctive weights to terms related to events. On timelines term significance is calculated by comparing term distribution of the documents on that day with that on the total document collection reported, and used to represent the document vectors on that day. Since two languages can provide more information than one language, term significance is measured on each language space and used to refer the other language space as a bridge on multilingual spaces. Evaluating the method on Korean and Japanese news articles, our method achieved $14.3{\%}\;and\;16.7{\%}$ improvement for mono- and multi-lingual story pairs, and for multilingual story pairs, respectively. By measuring the space density, the proposed weighting components are verified with a high density of the intra-event stories and a low density of the inter-events stories. This result indicates that the proposed method is helpful for multilingual story link detection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.555-567
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• 2010

Unlike single-hop systems, multi-hop systems that use relay nodes assign a part of the overall resources to relay communications. If efficient resource allocation schemes are not adopted, this leads to a loss of resources. Moreover, because we may not be able to guarantee high-link performance due to the adjacent-cell interference in relay-based cellular systems, resource efficiency can be severely decreased. In this paper, we propose efficient resource allocation schemes for downlink relay-based networks in 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution)-Advanced systems. Unlike conventional schemes that have static resource regions for each data link, the proposed schemes dynamically allocate the resources of each link to resource blocks, by considering the channel state and the capacity of each link. We also propose resource overlapping schemes in which two different links overlap at the same resource region, so as to improve cell or user throughput performance. The proposed resource overlapping schemes do not require additional processes such as interference cancellation in users, thank to considering additional interference from resource overlapping in advance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.879-888
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• 2000

In this paper, the performance of IS-95B CDMA system adopting multi-code scheme for data service on the forward link is obtained by theoretical analysis and computer simulation. The wireless channel is assumed to include AWGN, MUI(Multi-User Interference), and MPI(Multi-Path Interference), and multipath Rayleigh fading modeled by TDL(Tapped Delay Line). To obtain actual performance, IS-95B system using PN codes(M-sequence) concatenated with Walsh codes is considered. The BER performance of voice/data service satisfying QoS requirement and the maximum capacity of voice users is derived in terms of various system parameters(voice activity factor, required SNR of voice/data users, the number of multi-codes, the number of voice/data users.,etc.). As a result, under the condition that the maximum allowable number of voice user is 38 in voice only system, as the number of multi-code is decreased by 1, the maximum allowable number of voice user is increased by 5% for system with 1 data user and 22.3% for system with 4 data users. Therefore, it is possible to increase maximum allowable number of users in IS-95B CDMA system by appropriate control of the number of multi-codes and required SNR according to channel environment and traffic characteristic.

• Journal of Convergence Society for SMB
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• v.6 no.4
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• pp.17-23
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• 2016

With the advance of ICT, the Internet has been creating new services in various fields. However, due to the architectural problem of the Internet, it may inhibit the development of network architectures and various services. Network virtualization is being investigated as an alternative to overcome the architectural problem of the Internet and a virtual network resource allocation algorithm is a very important issue. In this paper, we propose a multiple path resource allocation algorithm with shared backup bandwidth in order to overcome single link failure. It will be improved survivability of the virtual networks. Through our experiments, we confirmed that the multi-path creation time of the proposed algorithm has about 50% performance improvement than previous works.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.209-215
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• 2006

Now, in this paper, going to present you with an Idea related to a new inverter of multi-step voltage source, that Is, the double-connected 12-step inverter with an auxiliary circuit. It possibly can be 24-step inverter with 3-phase voltage source which will enable us make full application even to medium and high power-level Motor drive, UPS, STATCOM, SVC, etc. in which the PWM method could not be employed. 24-step operation can be obtained from the link between the existing 12-step inverter and the additional auxiliary circuit in which the transformer of auxiliary circuit generates ripple voltage delivered to the inverter. Through a lot of experiments and simulations, (from which the validity of this scheme is confirmed,) we came to the conclusion that the increase of the primary winding number on transformer by 2N(N=1,2,3....) leads to the 12M-step(M=2,3,4...) inverter. The validity of the proposed scheme is confirmed by the simulated and experimental results.

• Journal of the Korean Society of Costume
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• v.59 no.3
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• pp.145-156
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• 2009

This study proposes the product development through an organic link with multi-faceted analysis on the archetype of traditional costumes culture. In order to find ways to develop cultural products, Jogakbo was selected, and the research result is as following. 1. Analysis on the types of Jogakbo products sold in the market shows that there are not only living, stationary, and fashion items, but also DIY packages. In terms of materials used, most of these Jogakbo products were made of fabric or mixture of different materials. These products displayed similar tendency by reflecting formative characteristics of Jogakbo. 2. This study analyzed the color, surface composition, material, manufacturing, and usage of Jogakbo. The rotor of Jogakbo is mostly composed of mono tone colors or Obangsac(five-element colors). The mono tone colors carries environmentally friendly meaning as it is using the natural color and Obangsac means harmony. Moreover, the surface composition of Jogakbo represents the expansion through connection and its material is also meaningful in that it is recycling. Manufacturing of Jogakbo has educational significance, fortune-wishing characteristics, decorative function, it also gives a gratification of handcraft. The usage of Jogakbo is a multi-(unctional article whose form is determined by an item that is held inside it. 3. Through the analysis on Jogakbo, this study presents the baby wear in relation to the ere-friendliness of colors, brooch sets using the surface composition, dresses using recycling fabric, children's educational instruments with educational significance, as well as multi-functional packages in regards to usage of Jogakbo.