• Tribology and Lubricants
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• v.34 no.1
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• pp.16-22
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• 2018

Cylindrical turbine guide bearings (TGBs) with simple plain pads have conventionally been used in vertical hydro-power turbine-generator applications in order to provide turbine runner shafts with smooth rotation guides and supports. To overcome low-load/low-eccentricity performance drawbacks, such as very low film stiffness and lack of design credibility in the stiffness values themselves, of conventional cylindrical TGBs, the introduction of a rotational-directional leading-edge taper to each partitioned pad, simply pad leading-edge taper, has been found to be very effective in enhancing their design-application availability and usefulness. In this study, we investigate the effects of taper angle and length for given taper heights in detail in order to systematically establish the effectiveness of design on the performance improvement of vertical hydro-power application cylindrical TGBs with pad leading-edge tapers. The analysis results with $4-Pad{\times}1-Row$ cylindrical TGBs show that the lubrication performance of the cylindrical TGBs is optimized with an approximate taper angle ratio of 0.8 and taper length ratio of 0.9. We conclude that the introduction of pad leading-edge tapers along with the optimization of taper designs can be very effective in improving the overall operation reliability of cylindrical TGBs and the rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems as well, to which the TGBs are applied.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.3
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• pp.29-34
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• 2008

Demand for car navigation systems has been an explosive increase because of prevalence of owner-drivers, spare time spread, and so on. In addition, car navigation systems are achieving a rapid growth to be the important part of telematics industry with services such as real-time traffic information and DMB(Digital Multimedia Broadcasting). The network data, one of the composition components in car navigation systems, is most important component because that is abstract of real world road network and base data in pathfinding. However most of the car navigation systems have been stand-alone system. Thus user's network data becomes outdated according to the time passing and does not reflect the change of road information in real world. To overcome this problem, users have to update network data in car navigation systems periodically. This method is quite cumbersome process. For this reason, this study proposed a new update method to serve the difference network data on user's device and the real world in real time, and simulated to verify.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.155-164
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• 2009

Digital Content Marketplace based on Interactive Media is defmed as the marketplace for content service between contents supplier and consumer through iDTV environment. This Marketplace is increasing interest to u-Life service with Digital Environment. To Interactive Media, it can contribute to enhance its effectiveness by developing various contents and service model in the initial phase of broadcasting-communication convergence. This study designed metadata using Digital Content marketplace based on Interactive Media. Specially the matadata designing include recommendation-tag for supply supplementary content. It can support self-directed action. Through basic metadata with weight value, it is designed to support supplementary content customer to want on the marketplace. Recommendation-System can be built by many method and to recommend the service content including explicit properties using collaborative filtering method can solve limitations in existing content recommendation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.66-72
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• 2011

In Japan, the specification for digital terrestrial television broadcasting systems has been approved for employing a transmission scheme for ISDB-T, which can accommodate HDTV service and portable mobile reception by adapting segmentation of frequency. In this paper, we have developed 3.5 inch mobile TV according to One-Seg system and presented the results of our development. In addition, we introduce two diversity schemes to compensate the defect that signal is interrupted when the portable TV is moving fast. In order to achieve a reliable communication in One-Seg system, we introduce STD(space time diversity) which uses more than 2 antennas at TX and cooperative reception diversity which utilizes signal-exchanging between different mobile terminals. And, its performance enhancements to reception reliability of previous system are evaluated by computer simulations.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.35-42
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• 2008

In this paper, we propose a fast coeff_token decoding method based on the re-constructed VLCT. Since the conventional decoding method is still based on large memory accesses, it is not suitable for the multimedia services such as PMP, PMB, DVH-H where fast decoding and low power consumption are required. Based on the analysis for the codeword structure, new structure of the codeword and the corresponding memory architecture are developed in this paper. The simulation results show that the proposed algorithm achieves memory access saving from 10% to 57%, compared to the conventional decoding method. This meant that the issues of tow power consumption and high speed decoding can be resolved without video-quality and coding efficiency degradation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1057-1063
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• 2007

To analyze the performance of mobile communication systems, the exact information of the carrier-to-interference ratio is important. Under the presence of an interferer in a cell, the carrier-to-interference ratio of the receiver is determined by the ratio between the informer-receiver distance$(d_0)$ and the receiver-interferer distance$(d_1)$. In this paper, we derive the carrier-to-interference distribution based on $d_0/d_1$ values using the geometric relation among the informer, interferer and receiver, and confirm its exactness using the simulation result. We also apply the derivation result to a system with the adjacent channel interference, and analyze the outage probability.

• Journal of Digital Contents Society
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• v.15 no.5
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• pp.631-642
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• 2014

The main memory DBMS is operated which the contents of the table that resides on a disk at the same time as the drive is in the memory. However, because the main memory DBMS stores the data and transaction log file using the disk file system, there are a limit to the speed at which the CPU accesses the memory. In this paper, I evaluated the performance through analysis of the application side difference the technology that has been implemented in Altibase system of main memory DBMS and Sybase of disk-based DBMS. When the application performance of main memory DBMS is in comparison with the disk-based DBMS, the performance of main memory DBMS was outperformed 1.24~3.36 times in the single soccer game, and was outperformed 1.29~7.9 times in the soccer game / special soccer. The result of sale transaction response time showed a fast response time of 1.78 ~ 6.09 times.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.137-148
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• 2007

Due to the advance of technology, the technology of various media is rapidly converged into digital technology. However, the conversion into digital radio is not achieved in korea yet. This paper is to suggest the best method of digital conversion of radio in korea by examining some conversion examples in foreign countries. In addition, the survey results on radio audience attitude is analysed by 2,000 audience samples in Korea based on the literature analysis. Radio is the unique media which have the strengths such as mobility, individuality, presence, broad coverage and instant. Most of all, radio cannot help keeping continuously the public broadcasting service in the future. So, the conversion into digital radio is crucial to sustain the competitiveness in digital media environment. This paper suggested that the digital conversion of radio broadcasting needs DRM transmission and should pursuit the policy which is distinguished between a AM and a standard FM, and between domestic broadcast and an international broadcast. Additionally, this paper proposed that we need to develop the multiple device for receiving of signal and the setting of standard technology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.315-320
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• 2010

In this paper, an internal TDMB(Terrestrial Digital Multimedia Broadcasting) antenna for mobile phone is proposed. The overall dimension of designed antenna with substrate is 30 mm$\times$5 mm$\times$0.6 mm. The proposed antenna consists of a meander type radiator which is connected front- and back-plane of Kapton substrate by via hole and parasitic element for tuning the resonant frequency. And to compensate the electric length of desired frequency, passive inductor is used for matching element. Measured gain of the implemented antenna -17.6 dBi at 174 MHz, -13.01 dBi at 195 MHz, and -14.9 dBi at 216 MHz.

• Information and Communications Magazine
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• v.25 no.1
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• pp.5-11
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• 2008

우리 경제의 성장잠재력 저하에 대한 우려가 심화되는 상황에서 국민소득 2만불 시대 견인을 위해 2004년 수립한 IT 산업 발전전략이 IT839이다. 신성장동력 핵심기술 개발 등 IT839전략에 힘입어 세계 최초로 WiBro, DMB 기술개발과 국제표준화에 성공하는 등 IT분야 기술개발을 주도하여, 선진국과의 기술격차가 1년 이상 단축되었으며, 특히, 이동통신 DIV 분야는 미국, 일본 등 선진국 수준으로 경쟁력이 향상되는 성과를 보았다. 한편, 최근 IT를 둘러싸고 있는 환경은 IT를 기반으로한 융복합화 진전, 글로벌화 심화, 인터넷 확산과 웹의 진전이다. 2008년에는 이런 환경변화 속에서 IT산업의 지속적인 성장을 위한 전략을 수립.추진할 계획이다. 무선 융합환경에서 신시장 창출 및 선점, 고부가가치 IT산업의 집중 육성, IT중소기업, 핵심인력 양성 등 경쟁력 향상을 위한 기반 구축도 강화한다. IT R&D 정책은 기초 원천기술분야 R&D 투자비중을 확대하고, IT와 비IT융합 등 융합분야 기술개발 투자도 확대할 것이다. 혁신형 IT 중소기업 육성을 위해 민간 정책협력 네트워크인 IT전문협의회 운영을 개선하고, 중소기업의 원가절감을 위한 공통서비스 확대, 대 중소 기업의 상생협력을 제도화는 등 IT정책 인프라도 고도화한다. 또한, 반도체, 디스플레이 이후의 글로벌 주력품목군으로 IT SoC, u-센서, IT-BT-NT 융합분야 등 3대 핵심분야를 선정하여 집중 육성하고, 부품기업간 협업 활성화를 적극 유도할 것이다. 시장이 원하는 글로벌 수준의 인재양성을 목표로 공학교육인증 확산, IT 융합분야를 중심으로 대학의 R&D 지원도 강화하며, 전공역략을 갖춘 IT 전문인력, 석박사급 핵심 연구개발 인력, IT재직자 교육 등 시장이 원하는 맞춤형 인력양성도 병행 추진한다. 마지막으로 SW산업의 글로벌 경쟁력을 제고하고 신시장 창출을 위해 노력도 강화한다. 조선, 자동차 등 비 IT분야의 SW활용을 확산하기 위한 선도프로젝트를 추진하고, 틈새분야 중 세계적 시장점유율을 갖춘 중소기업 제품에 임베디드SW를 탑재하여 첨단기능을 구현하는 시범사업도 적극 추진할 계획이다.