• Title/Summary/Keyword: adaptation mechanism

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DC Servo Motor Control using Model Reference Adaptive Fuzzy Controller (모델 기준 적응 퍼지 제어기를 이용한 DC 전동기 제어)

  • Son, Jae-Hyun;Kim, Je-Hong
    • Journal of the Korean Institute of Telematics and Electronics T
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    • v.36T no.4
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    • pp.60-70
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    • 1999
  • In this paper, model reference adaptive fuzzy controller (MRAFC) was proposed in order to overcome the difficulty of extracting rules and defects of the adaptation performance in the FLC. MRAFC comprised inner feedback loop consisting of the FLC and plant, and outer loop consisting of an adaptation mechanism which was designed for tuning a control rule of the FLC. A reference-model was used for design criteria of a fuzzy controller which characterizes and quantizes the control performance required in the overall control system. Tuning control rules of FLC is performed by the adaptation mechanism. The performance of proposed algorithm was verified through experiment for the DC servo motor.

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ROBHAZ-DT : Variable Configuration Double-Track Mobile Robot for Hazardous Environment Applications

  • Changhyun Cho;Park, Changwoo;Sungchul Kang;Kim, Munsang;Lee, Cheonghee;Kwak, Yoon-Keun
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.30.4-30
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    • 2001
  • In this paper, design and integration of a newly developed double-tracked mobile robot called ROBHAZ-DT are introduced. It is designed to carry out military and civil missions in various hazardous environments such as the areas of fire, war, disaster and mine field etc. ROBHAZ-DT is configured with three mechanical bodies, namely front, rear and main body. By using its rotational passive adaptation mechanism equipped between the front and rear bodies, ROBHAZ-DT shows a good mobile capability on uneven terrain including stairs. The passive adaptation mechanism reduces energy consumption and offers simplicity in the design of the ROBHAZ-DT ...

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Bandwidth-Efficient Live Virtual Reality Streaming Scheme for Reducing View Adaptation Delay

  • Lee, Jongmin;Lee, Joohyung;Lim, Jeongyeon;Kim, Maro
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.1
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    • pp.291-304
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    • 2019
  • This paper proposes a dynamic-tiling-based bandwidth-efficient (DTBE) virtual reality (VR) streaming scheme. We consider 360-degree VR contents with multiple view points such as the front, back, upper, and bottom sides. At a given time, the focus of a client is always bound to a certain view among multiple view points. By utilizing this perspective, under our proposed scheme, tiles with high encoding rates are selectively assigned to the focused view where multiple view points consist of multiple tiles with different encoding rates. The other tiles with low encoding rates are assigned to the remaining view points. Furthermore, for reducing view adaptation delay, we design a novel rapid view adaptation mechanism that selectively delivers an I-frame during view point updates by using frame indexing. We implement the proposed scheme on a commercial VR test bed where we adopt the MPEG media transport (MMT) standard with high-efficiency video coding (HEVC) tile modes. The measurement-based experiments show that the proposed scheme achieves an average data usage reduction of almost 65.2% as well as average view adaptation delay reduction of almost 57.7%.

Efficient Video Streaming Mechanism through a New Rate Adaptation Scheme (새로운 전송률 적응기법을 통한 효율적인 비디오 스트림 전송 메커니즘)

  • Lee, Sun-Hun;Chung, Kwang-Sue
    • Journal of Broadcast Engineering
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    • v.14 no.1
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    • pp.44-58
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    • 2009
  • To provide efficient video streaming service over a wireless networks, the rate adaptation scheme should be applied at the low layer and the quality adaptation scheme should be considered at the high layer. In this paper, we propose a new cross-layer design which includes rate adaptation scheme at the MAC/PHY layers and quality control at the application layer. Proposed rate adaptation scheme improves the wireless channel utilization by transmitting the consecutive frames and selects optimal transmission mode by calculating the goodputs for each transmission mode. Based on selected transmission mode, the rate adaptation scheme calculates the rate limits and informs that to the application layer. Then the video streaming application utilizes this rate limits to adjust the quality of the video stream. Through performance evaluations, we prove that our cross-layer design improves the quality of the wireless video streaming service by means of the proposed rate adaptation scheme.

Inter-partner Fit Mechanisms for Sustainable Joint Ventures: Evidence from Japanese Firms in Korea

  • Kim, Jang-Hyun;Yoshimoto, Koji;Bae, Il-Hyun;Yoon, Ki-Chang
    • Journal of Korea Trade
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    • v.25 no.3
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    • pp.134-152
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    • 2021
  • Purpose - Our study aimed to examine the roles of conflict management in maintaining a sustainable good relationship between joint venture (JV) partners. Although the concepts of relational capital, mutual commitment, and cultural adaptation have been neglected in previous research on interorganizational relationships, we treated them as inter-partner fit mechanism capabilities of affecting the level of satisfaction in a relationship with a JV partner. Design/methodology - In order to test hypotheses, we sent a questionnaire to Japanese firms operating JVs in South Korea and asked whether their levels of satisfaction with their JV partners increase when conflict management techniques are used to reduce the conflicts that usually arise between partners. Findings - The results of our study suggested that it is important for firms participating in a JV to construct and reinforce an inter-partner fit mechanism that enables them to maintain a favorable partnership. In addition, we suggested that relational capital, cultural adaptation, and mutual commitment influence conflict reduction and the level of satisfaction experienced in JVs. Moreover, the results showed that conflict management has a significant effect on developing soild partnerships and performance in JV situations. Originality/value - We advanced a new paradigm about conflict management and suggested methods of research propositions that are well grounded in the latest findings in conflict management research pertaining to JVs.

MRAS Speed Estimator Based on Type-1 and Type-2 Fuzzy Logic Controller for the Speed Sensorless DTFC-SVPWM of an Induction Motor Drive

  • Ramesh, Tejavathu;Panda, Anup Kumar;Kumar, S. Shiva
    • Journal of Power Electronics
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    • v.15 no.3
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    • pp.730-740
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    • 2015
  • This paper presents model reference adaptive system speed estimators based on Type-1 and Type-2 fuzzy logic controllers for the speed sensorless direct torque and flux control of an induction motor drive (IMD) using space vector pulse width modulation. A Type-1 fuzzy logic controller (T1FLC) based adaptation mechanism scheme is initially presented to achieve high performance sensorless drive in both transient as well as in steady-state conditions. However, the Type-1 fuzzy sets are certain and cannot work effectively when a higher degree of uncertainties occurs in the system, which can be caused by sudden changes in speed or different load disturbances and, process noise. Therefore, a new Type-2 FLC (T2FLC) - based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties, improve the performance, and is also robust to different load torque and sudden changes in speed conditions. The detailed performance of different adaptation mechanism schemes are performed in a MATLAB/Simulink environment with a speed sensor and sensorless modes of operation when an IMD is operates under different operating conditions, such as no-load, load, and sudden changes in speed. To validate the different control approaches, the system is also implemented on a real-time system, and adequate results are reported for its validation.

Quality Adaptation with Temporal Scalability for Efficient Video Streaming (효율적인 비디오 스트리밍을 위한 일시적인 확장성을 이용한 품질 적응 기법)

  • Lee, Sun-Hun;Chung, Kwang-Sue
    • Journal of KIISE:Information Networking
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    • v.34 no.3
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    • pp.143-155
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    • 2007
  • In video streaming applications over the Internet, TCP-friendly rate control schemes are useful for improving network stability and inter-protocol fairness. However it does not always guarantee a smooth quality for video streaming. To simultaneously satisfy both the network and application requirements, video streaming applications should be quality-adaptive. In this paper, we propose a new quality adaptation mechanism to adjust the quality of congestion controlled video stream by controlling the frame rate. Based on the current network condition, it controls the frame rate and sending rate of video stream. Through the simulation, we prove that our adaptation mechanism appropriately adjusts the quality of video stream while improving network stability.

A flexible mechanism for supporting various profiles in the content adaptation system (콘텐츠 적응화 시스템에서의 다양한 프로파일을 지원하기 위한 유연성 있는 매커니즘)

  • Lim, Mok-Hwa;Chang, Byung-Chul;Kang, Soo-Young;Cha, Jae-Hyuk
    • Journal of Digital Contents Society
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    • v.7 no.1
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    • pp.25-33
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    • 2006
  • As becoming the age of ubiquitous, there are many discussion and publication for standards to express platform profile. These various platform profiles have some problems. The solve these problems, we propose and develop a new posting mechanism which improve the performance of contents adaptation engine by simplifying platform profile and processing various type of platform profiles; we introduce the way to integrate different profiles to solve nut to recognize the profile which is used by different adaptation system and simplify platform profile by grouping the similar attributes of platform profiles. Proposed system can processing different profiles and also the system overhead to processing a profile and creating a dynamic profile has reduced. As a result overall performance of content adaptation system has increased.

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Machine-Learning-Based Link Adaptation for Energy-Efficient MIMO-OFDM Systems (MIMO-OFDM 시스템에서 에너지 효율성을 위한 기계 학습 기반 적응형 전송 기술 및 Feature Space 연구)

  • Oh, Myeung Suk;Kim, Gibum;Park, Hyuncheol
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.5
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    • pp.407-415
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    • 2016
  • Recent wireless communication trends have emphasized the importance of energy-efficient transmission. In this paper, link adaptation with machine learning mechanism for maximum energy efficiency in multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) wireless system is considered. For reflecting frequency-selective MIMO-OFDM channels, two-dimensional capacity(2D-CAP) feature space is proposed. In addition, machine-learning-based bit and power adaptation(ML-BPA) algorithm that performs classification-based link adaptation is presented. Simulation results show that 2D-CAP feature space can represent channel conditions accurately and bring noticeable improvement in link adaptation performance. Compared with other feature spaces, including ordered postprocessing signal-to-noise ratio(ordSNR) feature space, 2D-CAP has distinguished advantages in either efficiency performance or computational complexity.

Metabolomics reveals potential plateau adaptability by regulating inflammatory response and oxidative stress-related metabolism and energy metabolism pathways in yak

  • Huang, Meizhou;Zhang, Xin;Yan, Wenjun;Liu, Jingjing;Wang, Hui
    • Journal of Animal Science and Technology
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    • v.64 no.1
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    • pp.97-109
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    • 2022
  • Species are facing strong selection pressures to adapt to inhospitable high-altitude environments. Yaks are a valuable species and an iconic symbol of the Qinghai-Tibet Plateau. Extensive studies of high-altitude adaptation have been conducted, but few have focused on metabolism. In the present study, we determined the differences in the serum metabolomics between yaks and the closely related species of low-altitude yellow cattle and dairy cows. We generated high-quality metabolite profiling data for 36 samples derived from the three species, and a clear separation trend was obtained between yaks and the other animals from principal component analysis. In addition, we identified a total of 63 differentially expressed metabolites among the three species. Functional analysis revealed that differentially expressed metabolites were related to the innate immune activation, oxidative stress-related metabolism, and energy metabolism in yaks, which indicates the important roles of metabolites in high-altitude adaptation in yaks. The results provide new insights into the mechanism of adaptation or acclimatization to high-altitude environments in yaks and hypoxia-related diseases in humans.