• 제목/요약/키워드: Jangho

검색결과 102건 처리시간 0.023초

Energy-Efficient Opportunistic Interference Alignment With MMSE Receiver

  • Shin, Won-Yong;Yoon, Jangho
    • IEIE Transactions on Smart Processing and Computing
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    • 제3권2호
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    • pp.83-87
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    • 2014
  • This paper introduces a refined opportunistic interference alignment (OIA) technique that uses minimum mean square error (MMSE) detection at the receivers in multiple-input multiple-output multi-cell uplink networks. In the OIA scheme under consideration, each user performs the optimal transmit beamforming and power control to minimize the level of interference generated to the other-cell base stations, as in the conventional energy-efficient OIA. The result showed that owing to the enhanced receiver structure, the OIA scheme shows much higher sum-rates than those of the conventional OIA with zero-forcing detection for all signal-to-noise ratio regions.

수직축 건물풍력발전기와 연동된 윈드가이드의 유동특성해석 (Flow Characteristics Analysis of Wind guide in Conjunction of Vertical Axis Building Wind Turbine)

  • 손영우;김용이;이장호
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2011년도 추계학술대회 초록집
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    • pp.34.2-34.2
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    • 2011
  • Wind guide can be installed on the top of buildings to collect wind. In this study, optimum shape of wind guide is developed, and proposed to combinate with the vertical wind turbine. Impact of parameters for wind guide is analyzed with several cases planned by Taguchi test plan. Front angle, rear angle, and roof angle are selected as key variables and changed into four different levels. By the experimental plan, totally, 64 cases are reduced to 16 cases of analysis. With optimum design of wind guide, the installed vertical axis wind turbines can be operated with maximum power output.

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Review of the Improvement Plans on Catenary Systems for Speed Increase in Gyeongbu High-Speed Line

  • Eum, Ki Young;Yun, Jangho;Lee, Kiwon;Kim, Jung Hwan
    • International Journal of Railway
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    • 제6권2호
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    • pp.64-68
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    • 2013
  • In recent years, the speed of a train has been recognized as one of the important factors to determine the competitiveness as a mean of transportation. In line with this, infrastructure improvements and enhancements are being made with increases in the speed of train. Accordingly, there is a need to establish plans for infrastructure improvements through a comprehensive analysis of signals, track/civil engineering, catenary and environment, etc. to improve the speed of a train of high-speed train service sections in Korea. This study proposes improvement plans for catenary systems by investigating the possibility of improvements through performance analysis of catenary equipment by speed increase based on the analysis on catenary systems in Gyeongbu high-speed line, and analysis the applicability of catenary improvements and economic feasibility.

CONDUIT을 이용한 헬리콥터 조종성에 대한 비행제어법칙 설계 및 최적화 (Control Law Design Optimization for Helicopter Handling Qualities Using CONDUIT)

  • 이장호;김응태;이석천;유혁
    • 항공우주시스템공학회지
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    • 제6권2호
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    • pp.23-27
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    • 2012
  • The evaluation of simulation models against ADS-33 quantitative rotorcraft handling qualities metrics has, in the past, been a time consuming effort, involving many individual analyses in both the time and frequency domains. Manual tuning of control system parameters to meet handling qualities and performance specifications has been cumbersome and complicated. Performing rigorous trade-off studies for numerous variations in the control system is too time consuming to be practicable. With the complex interaction of time- and frequency based specifications for the closed- and broken-loop responses, it is difficult to know if the design makes the most effective use of the available control power. The Control Designer's Unified Interface (CONDUIT) software makes possible rapid optimization and trade-offs of design configurations against handling qualities specifications.

다분지 응축기의 냉매유량 분배에 미치는 중력의 영향을 고려한 해석방법 (Analysis of the Gravity Effect on the Distribution of Refrigerant Flow in a Multi-circuit Condenser)

  • 이장호;김무환
    • 설비공학논문집
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    • 제16권12호
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    • pp.1167-1174
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    • 2004
  • The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

Investigation on Performance Characteristics of IPM for Electric Vehicles Considering Driving Conditions and Pole-Slot Combinations

  • Seo, Jangho
    • Journal of Magnetics
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    • 제18권3호
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    • pp.268-275
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    • 2013
  • This paper shows the characteristics of performance for interior permanent magnet machine (IPM) considering driving conditions such as maximum torque per ampere (MTPA) and flux-weakening control especially in terms of harmonic loss. In particular, based on finite element analysis (FEA), permanent magnet (PM) eddycurrent loss and the harmonic iron loss have been computed where the models have been intentionally designed to identify the effects of pole-slot combinations on the loss while maintaining the required power for electric vehicle. From the analysis results, it was shown that the rotor iron loss and PM eddy-current loss of machine employing fractional slot winding are extremely large at load condition. Furthermore, it was revealed that the harmonic iron loss at high-speed operation is mainly distributed over stator teeth and rotor surface, which may aggravate cooling system of the rotor structure in the vehicle.

연안환경 모니터링을 위한 홍합(Mytilus coruscus)의 체내 수은 함량 분석 (Determination of Mercury in Korean Mussels (Mytilus coruscus) for Marine Environmental Monitoring)

  • 이수용;이장호
    • 한국환경과학회지
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    • 제27권12호
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    • pp.1291-1298
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    • 2018
  • Marine ecosystems are frequently exposed to a variety of chronic and acute pollutants derived from anthropogenic production and consumption activities. Mussels are sessile (can provide location-specific information), medium-sized (have enough tissue matrix for chemical analysis) filter-feeders (show accumulation of pollutant chemicals from seawater). These biological and ecological characteristics make mussels virtually ideal for pollution monitoring. In this study, Korean mussels (Mytilus coruscus) were collected from nine different sites situated along the coasts of the western sea to the eastern sea of Korea in 2017. Total mercury concentration was highest (mean ${\pm}$ standard error, $92.7{\pm}3.5ng/g\;dry$) on Baengnyeongdo Island in the western sea, and the sites in the southern sea showed the lowest mean concentrations (42.3 - 44.5 ng/g dry). These results were discussed in terms of possible pollution sources.

블록체인에서 디지털서명 국내외 동향 분석 (An Analysis on Trend of Digital Signature in Blockchain)

  • 나장호;김혜영
    • 한국정보처리학회:학술대회논문집
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    • 한국정보처리학회 2022년도 춘계학술발표대회
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    • pp.268-271
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    • 2022
  • 본 논문은 블록체인에서 사용 중인 디지털서명을 국내외 동향으로 분석하여 향후 기존 디지털서명 기술이 새로운 대안의 디지털서명으로 대체될지 전망을 분석하였다. 디지털서명의 국내외 동향은 해시함수, 타원곡선, 디지털서명 알고리즘 등으로 구별하여 파악하였다. 디지털서명의 해외 동향에서는 ECDSA 외에 몇몇 새로운 알고리즘 도입이 진행 중에 있었지만 국내 동향에서는 단 하나의 사례도 찾기 힘들 정도로 여전히 대부분 업체에서는 ECDSA를 사용 중에 있었다. 아직까지 국내에서는 ECDSA의 채택률이 압도적이지만 해외에서는 조금씩 새로운 디지털서명을 채택 중에 있었다. 향후에는 ECDSA의 채택률이 줄어들고 새로운 디지털서명의 채택률이 올라갈 것으로 예상된다.

중등기하에서 Freudenthal의 수학화 활동을 위한 학습자료 개발과 적용 (Development and Application of Learning Materials for Freudenthal's Mathematising Activities in the Middle School Geometry)

  • 최종철;김홍철
    • 한국학교수학회논문집
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    • 제11권1호
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    • pp.69-96
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    • 2008
  • 본 논문은 현행 중등수학에서 기하교육의 문제점을 인식하고 Freudenthal의 학습이론에 토대를 둔 수학화 활동에 적합한 학습자료의 개발 및 교수-학습활동에 따른 수학화 과정을 분석하는데 그 목적이 있다. 이를 위해 중학교 수학 8-나 단계 기하영역을 중심으로 Freudenthal의 학습 이론과 관련된 활동 중심의 학습자료와 van Hiele의 학습 단계 이론을 토대로 교수-학습 모형을 개발하여 수업에 적용한 후 수학화 활동의 효과를 분석한다.

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스마트 SNS 맵: 위치 정보를 기반으로 한 스마트 소셜 네트워크 서비스 데이터 맵핑 및 시각화 시스템 (Smart SNS Map: Location-based Social Network Service Data Mapping and Visualization System)

  • 윤장호;이승훈;김현철
    • 한국멀티미디어학회논문지
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    • 제19권2호
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    • pp.428-435
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    • 2016
  • Hundreds of millions of new posts and information are being uploaded and propagated everyday on Online Social Networks(OSN) like Twitter, Facebook, or Instagram. This paper proposes and implements a GPS-location based SNS data mapping, analysis, and visualization system, called Smart SNS Map, which collects SNS data from Twitter and Instagram using hundreds of PlanetLab nodes distributed across the globe. Like no other previous systems, our system uniquely supports a variety of functions, including GPS-location based mapping of collected tweets and Instagram photos, keyword-based tweet or photo searching, real-time heat-map visualization of tweets and instagram photos, sentiment analysis, word cloud visualization, etc. Overall, a system like this, admittedly still in a prototype phase though, is expected to serve a role as a sort of social weather station sooner or later, which will help people understand what are happening around the SNS users, systems, society, and how they feel about them, as well as how they change over time and/or space.