• Title/Summary/Keyword: 트레이드오프

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Efficient Spectrum Sensing Based on Evolutionary Game Theory in Cognitive Radio Networks (인지무선 네트워크에서 진화게임을 이용한 효율적인 협력 스펙트럼 센싱 연구)

  • Kang, Keon-Kyu;Yoo, Sang-Jo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39B no.11
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    • pp.790-802
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    • 2014
  • In cognitive radio technology, secondary users can determine the absence of PU by periodic sensing operation and cooperative sensing between SUs yields a significant sensing performance improvement. However, there exists a trade off between the gains in terms of probability of detection of the primary users and the costs of false alarm probability. Therefore, the cooperation group must maintain the suitable size. And secondary users should sense not only the currently using channels and but also other candidates channel to switch in accordance with sudden appearance of the primary user. In this paper, we propose an effective group cooperative sensing algorithm in distributed network situations that is considering both of inband and outband sensing using evolutionary game theory. We derived that the strategy group of secondary users converges to an ESS(Evolutionary sable state). Using a learning algorithm, each secondary user can converge to the ESS without the exchange of information to each other.

The Effect of Low Boiling Point Oxygenates on the Diesel Engine Performance and Emissions (저비점 함산소물질이 디젤기관의 성능과 배기배출물에 미치는 영향)

  • 김봉석;송용식;궁본등
    • Journal of Energy Engineering
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    • v.13 no.1
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    • pp.20-27
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    • 2004
  • In the study, the effect of low boiling point oxygenates in high viscous fuels on the exhaust emissions has been investigated for a single cylinder DI diesel engine. It was tested to estimated change of engine performance and exhaust emission characteristics for the base fuels and low boiling point oxygenates blended fuel which have six kinds of fuels and various mixed rates. The results of the study may be con eluded as follows By blending of various low boiling point oxygenated agents to lower grade fuels, significant improvements were simultaneously obtained in smoke, CO, PM, SOF and BSEC. Especially, these trends were remarkably obtained by retarding injection timing, by decreasing boiling point and increasing blending contents of additives in case of oxygenated agents rather than non-oxygenated agents. Also, it was revealed that when 20 vol.% DMM added to high viscosity fuels and injection timing was retarded, Nox-smoke trade off relationship was much better than that of ordinary diesel fuel. Thus, lower grade fuels with high viscosity could be expected to be used efficiently and cleanly in diesel operation by blending low boiling point oxygenates.

Creative Resolution for Requirement Conflict Using Conflict Resolution Theory of TRIZ (TRIZ의 모순 해결 이론을 이용한 창의적 요구사항 충돌 해결)

  • Jung, Ji-Young;Kim, Jin-Tae;Park, Soo-Yong
    • Journal of KIISE:Software and Applications
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    • v.37 no.5
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    • pp.411-415
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    • 2010
  • The Conflicts between requirements may cause a failure of functions or even project. Currently, most of researches have focused on identifying requirements and some researchers have tried to resolve requirements conflicts but it was only based on requirement priority. This paper proposes the Creative Requirements Conflict Resolution (CRRC) to resolve requirement conflicts in a creative way using TRIZ methodology. TRIZ, which means the theory of solving inventor's problems, is made based on the analysis of over 2 million patent cases and helpful for developing a creative solution to resolve conflicts. CRRC classifies requirement conflicts into groups and then apply TRIZ theory related to each group. At the result of control experiment, CRRC provides the various kinds of creative solution for requirement conflicts.

Analysis of the electrical characteristics of the novel TIGBT with additional pMOS (새로운 구조의 pMOS 삽입형 TIGBT의 전기적 특성 분석)

  • Lee, Hyun-Duck;Won, Jong-Il;Yang, Yil-Suk;Koo, Yong-Seo
    • Journal of IKEEE
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    • v.14 no.1
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    • pp.55-64
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    • 2010
  • In this paper, we proposed the novel TIGBT with an additional p-type MOS structure to achieve the improved trade-off between turn-off and on-state voltage drop(Vce(sat)). These low on-resistance and the fast switching characteristics of the proposed TIGBT are caused by an enhanced electron current injection efficiency which is caused by additional p-type MOS structure. In the simulation result, the proposed TIGBT has the lower on state voltage of 1.67V and the shorter turn-off time of 3.1us than those of the conventional TIGBT(2.25V, 3.4us).

Analysis and Comparison for a 4-Coil Magnetic Resonance Wireless Power Transfer System (4-코일 자기 공진 무선 전력 전송 시스템의 해석법 연구)

  • Lee, Gunbok;Park, Wee Sang
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.2
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    • pp.168-179
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    • 2013
  • The critical point analysis(CA) and impedance matching analysis(IA) are performed and compared for a 4-coil magnetic resonance wireless power transfer system. Because the operating frequency splits at short distance while the efficiency drops drastically at long distance in this system, the optimization technique is needed for either a specific distance or efficiency at the fixed frequency. CA uses the critical point where shows maximum efficiency in the entire range and IA uses the impedance matching technique to achieve maximum efficiency at the specific distance. Comparison result shows that IA is more efficient than CA. Also, it shows one side matching has a tradeoff relationship comparing to both side matching. By using four spiral resonant coils, the analysis was experimentally verified. The measured data agreed well with the calculated data.

A Study on Consideration Factors of Traffic Safety Assessment on the Bridge Design-I (해상교량 건설을 위한 선박통항 안전성 검토요소에 관한 연구-I)

  • Park Young-Soo;Park Jin-Soo;Ko Jae-Yong;Jong Je-Yong;Lee Eun
    • Journal of Navigation and Port Research
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    • v.29 no.1 s.97
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    • pp.71-75
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    • 2005
  • From the viewpoint of navigation safety, it would be best if it's possible to build a bridge whose main span is wide enough, however, sometimes it may not be possible due to geographical or economic reason To construct the bridge on the shipping route, consideration factors for marine traffic safety must be investigated and examined from the viewpoint of marine traffic engineering. This study aims to secure marine traffic safety and maintain smoothly traffic flow through assessment qf these factors. As the first step, examination factors such as traffic volume, ship size and bridge width were assessed quantitatively using marine traffic flow simulation technique.

Simplified Near Optimal Downlink Beamforming Schemes in Multi-Cell Environment (다중 셀 환경에서 적은 복잡도를 갖는 준 최적 하향 빔형성)

  • Yang, Jang-Hoon;Kim, Dong-Ku
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.12C
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    • pp.764-773
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    • 2011
  • Despite enormous performance gain with multi-antenna transmission in the single cell environment, its gain diminishes out in the multi-cell environment due to interference. It is also very hard to solve the efficient downlink beamforming with low complexity in multi-cell environment. First, this paper shows that the asymptotically sum rate optimal downlink beamformings at low and high SNR are maximum ratio transmit (MRT) and zero forcing (ZF) beamforming in the multi-cell system, respectively. Secondly, exploiting the asymptotically optimal downlink beamforming, we develop simple two types of near optimal downlink beamforming schemes having the form of minimum mean squared error (MMSE) beamforming obtained from the dual uplink problem. For each type, three different subclasses are also considered depending on the computational complexity. The simulation results show that the proposed near optimum algorithms provide the trade-off between the complexity and the performance.

Two Aspects of the Game Playing Effect and Attitude toward Game Regulation :Focused on Game Genre (게임 플레이 효과의 양면성과 게임 규제 태도 연구 :게임 장르를 중심으로)

  • Jung, Chang Won
    • The Journal of the Korea Contents Association
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    • v.19 no.12
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    • pp.425-439
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    • 2019
  • This study looks at the social implications of gaming disorder by considering the situation in Korea. Focusing on specificity of game genres, this study analyzed two aspects of the game playing effect-positive(cognitive needs) and negative(game addiction)-and suggested directions for game regulation policies and game addiction studies, since game playing effects are closely related to game regulatory policy. To analyze game effects and attitudes to regulations, this study performed regression analysis based on the online survey. Results show that game playing effects and attitudes toward game regulation differ based on the nature of game genres. While longer gaming increased the effect of addiction, it also increased cognitive needs. Playing roleplaying, Aeon of Strife, and strategy game genres(RAS), which are subject to game regulation, increased game addiction levels but simultaneously contributed to increased cognitive needs. While playing augmented reality genres positively affected cognitive needs, it also showed favorable attitudes to general game regulation.

An Energy-Efficient Data-Centric Routing Algorithm for Wireless Sensor Networks (무선 센서 네트워크에서 에너지 효율적인 데이터 중심 라우팅 알고리즘)

  • Choi, Hyun-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.11
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    • pp.2187-2192
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    • 2016
  • A data-centric routing protocol considering a data aggregation technique at relay nodes is required to increase the lifetime of wireless sensor networks. An energy-efficient data-centric routing algorithm is proposed by considering a tradeoff between acquisition time and energy consumption in the wireless sensor network. First, the proposed routing scheme decides the sink node among all sensor nodes in order to minimize the maximum distance between them. Then, the proposed routing extends its tree structure in a way to minimize the link cost between the connected nodes for reducing energy consumption while minimizing the maximum distance between sensor nodes and a sink node for rapid information gathering. Simulation results show that the proposed data-centric routing algorithm has short information acquisition time and low energy consumption; thus, it achieves high energy efficiency in the wireless sensor network compared to conventional routing algorithms.

A Study on the Electrical Characteristics according to Growth of Trench SiO2 Inside Super Junction IGBT Pillar (Super Junction IGBT 필러 내부 Trench SiO2성장에 따른 전기적 특성에 관한 연구)

  • Lee, Geon Hee;Ahn, Byoung Sup;Kang, Ey Goo
    • Journal of IKEEE
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    • v.25 no.2
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    • pp.344-349
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    • 2021
  • This paper proposes a structure in which Trench SiO2 is grown inside of Super Junction IGBT P-Pillar. When observing the electric field in 3D, we checked the region where the electric field have not affected inside of the P-Pillar. The pillar region's portion resistance is varied by the breakdown voltage and size of each pillar, which reduces the size by growing SiO2 after trenching has no field effect inside of that. At 4.5kV the same breakdown voltage, it was confirmed that the On-state voltage drop improved by about 58%, 19% compared to Field Stop IGBT and conventional Super Junction IGBT.