• Title, Summary, Keyword: Transmission efficiency

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Energy Efficiency Analysis of Cellular Downlink Transmission with Network Coding over Rayleigh Fading Channels

  • Zhu, Jia
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.3
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    • pp.446-458
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    • 2013
  • Recently, energy-efficient cellular transmission has received considerable research attention to improve the energy efficiency of wireless communication. In this paper, we consider a cellular network consisting of one base station (BS) and multiple user terminals and explore the network coding for enhancing the energy efficiency of cellular downlink transmission from BS to users. We propose the network coded cellular transmission scheme and conduct its energy consumption analysis with target outage probability and data rate requirements in Rayleigh fading environments. Then, the energy efficiency in Bits-per-Joule is further defined and analyzed to evaluate the number of bits delivered per Joule of energy cost. Numerical results show that the network coded cellular transmission significantly outperforms the traditional cellular transmission in terms of energy efficiency, implying that given a Joule of energy cost, the network coded cellular transmission scheme can deliver more bits than the traditional cellular transmission.

Efficiency Analysis of Magnetic Resonance Wireless Power Transmission using Superconductor Coil According to the Changing Position of Transmission and Receiving Coils (초전도 코일을 적용한 자기공명방식 무선전력전송의 송·수신 코일 배열에 따른 효율 분석)

  • Kang, Min-Sang;Choi, Hyo-Sang;Jeong, In-Sung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.6
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    • pp.776-779
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    • 2014
  • In this paper, we analyzed the efficiency of magnetic resonance wireless power transmission (WPT) using superconductor coil according to the changing position of transmission and receiving coils. We implemented a WPT system using a magnetic resonance at a frequency of 63.1 kHz. Transmission and receiving coils using superconductor coil were wound on a spiral manner of diameter 100mm. For comparison, transmission and receiving coils using normal conductor coil were designed under the same condition. At a distance of 50mm, we measured efficiency when transmission-receiving coils were matched 25%, 50%, 75% and 100%. When a superconductor coil was applied to the transmission and receiving units, efficiency of WPT was very high. In addition, in the case of the superconducting transmission-receiving coils, when coils matched 100% the efficiency was 30% and matched 25% the efficiency was 8%.

Analysis of transmission efficiency of the superconducting resonance coil according the materials of cooling system

  • Lee, Yu-Kyeong;Hwang, Jun-Won;Choi, Hyo-Sang
    • Progress in Superconductivity and Cryogenics
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    • v.18 no.1
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    • pp.46-49
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    • 2016
  • The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

Efficiency Improvement of MLA (Micro Lens Array) using Aperture (Aperture를 이용한 MLA의 효율 개선)

  • Seo, Hyun-Woo;Nam, Min-Woo;Oh, Hae-Kwan;Ahn, Hyo-Chan;Kim, Tae-June;Wei, Chang-Hyun;Lee, Kee-Keun;Yang, Sang-Sik;Song, Yo-Tak
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.1
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    • pp.91-94
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    • 2011
  • This paper presents light transmission efficiency by optical adhesive thickness between MLA and aperture layer and by aperture hole size. The gap between MLA and Aperture layer is adjusted by the shim. The more optical adhesive thickness increases, the better light transmission efficiency increases up to a point. After that, the light transmission efficiency decreases because stray lights cannot transmit through the aperture layer owing to cut-off by aperture layer. And as a result of light transmission efficiency with changing aperture hole size, the light transmission efficiency is proportional to area of aperture hole. The more specified process is made, the better data and sample will be got.

Evaluation of the Photon Transmission Efficiency of Light Guides Used in Scintillation Detectors Using LightTools Code

  • Park, HyeMin;Joo, Koan Sik;Kim, Jeong Ho;Kim, Dong Sung;Park, Ki Hyun;Park, Chan Jong;Han, Woo Jun
    • Journal of Radiation Protection and Research
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    • v.41 no.3
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    • pp.282-285
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    • 2016
  • Background: To optimize the photon transmission efficiency of light guides used in scintillation detectors, LightTools code, which can construct and track light, was used to analyze photon transmission effectiveness with respect to light guides thickness. Materials and Methods: This analysis was carried out using the commercial light guide, N-BK 7 Optical Glass by SCHOTT, as a model for this study. The luminous exitance characteristic of the LYSO scintillator was used to analyze the photon transmission effectiveness according to the thickness of the light guide. Results and Discussion: The results of the simulations showed the effectiveness of the photon transmission according to the thickness of the light guide, which was found to be distributed from 13.38% to 33.57%. In addition, the photon transmission efficiency was found to be the highest for light guides of 4 mm of thickness and a receiving angle of $49^{\circ}$. Conclusion: Through such simulations, it is confirmed that photon transmission efficiency depends on light guide thickness and subsequent changes in the internal angle of reflection. The aim is to produce an actual light guide based on these results and to evaluate its performance.

5.8 GHz Microwave Wireless Power Transmission System Development and Transmission-Efficiency Measurement (5.8 GHz 마이크로파 무선전력전송 시스템 개발 및 전송효율측정)

  • Lee, Seong Hun;Son, Myung Sik
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.4
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    • pp.59-63
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    • 2014
  • Previous studies have selected wireless power transmission system using 2.45 GHz of ISM band, but the researches for 5.8 GHz microwave wireless power transmission have been relatively rare. The 5.8 GHz has some advantages compared with 2.45 GHz. Those are smaller antenna and smaller integrated system for RFIC. In this paper, the 5.8 GHz wireless power transmission system was developed and transmission efficiency was measured according to the distance. A transmitter sent the amplified microwaves through an antenna amplified by a power amplifier of 1W for 5.8 GHz, and a receiver was converted to DC from RF through a RF-DC Converter. In the 1W 5.8GHz wireless power transmission system, the converted currents and voltages were measured to evaluate transmission efficiency at each distance where LED lights up to 1m. The RF-DC Converter is designed and fabricated by impedance matching using full-wave rectifier circuit. The transmission-efficiency of the system shows from 1.05% at 0cm to 0.095% at 100cm by distance.

A Forward Speed Control of Head-feed Combine Using Continuously Variable V-belt Transmission -Transmission Characteristics of CVVT- (V-벨트 무단변속기(無段變速機)를 이용(利用)한 자탈형(自脫型) 콤바인의 주행속도(走行速度) 제어(制御)(II) - V-벨트 무단변속기(無段變速機)의 변속특성(變速特性) -)

  • Choi, K.H.;Ryu, K.H.;Cho, Y.K.;Park, P.K.
    • Journal of Biosystems Engineering
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    • v.16 no.3
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    • pp.239-247
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    • 1991
  • This study was conducted to investigate the feasbility of continuously variable V-belt transmission(CVVT) as automatic power transmission system of combine harvesters. An experimental set-up for testing the performance of CVVT and the automatic transmission system was designed and used to analyze the power transmission characteristics of CVVT. The transmission efficiency of CVVT was increased logarithmically with increase of the load of driven shaft, but was not affected by the speed ratios of transmission. More than 80% of transmission efficiency was obtained in the 25N-m load and more of driven-shaft, and the maximum efficiency was 88~91%. When rapid speed change of the CVVT was attempted, the speed of driven shaft was stabilized within about 0.4 seconds after shift operation in both cases of increasing and decreasing of the speed.

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Gateway Channel Hopping to Improve Transmission Efficiency in Long-range IoT Networks

  • Kim, Dae-Young;Kim, Seokhoon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.3
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    • pp.1599-1610
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    • 2019
  • Intelligent services have expanded as Internet of Things (IoT) technology has evolved and new requirements emerge to accommodate various services. One new requirement is transmitting data over long distances with low-power. Researchers have developed low power wide area (LPWA) network technology to satisfy the requirement; this can improve IoT network infrastructure and increase the range of services. However, network coverage expansion causes several problems. The traffic load is concentrated at a specific gateway, which causes network congestion and leads to decreased transmission efficiency. Therefore, the approach proposed in this paper attempts to recognize and then avoid congestion through gateway channel hopping. The LPWA network employs multiple channels, so wireless channel hopping is available in a gateway. Devices that are not delay sensitive wait for the gateway to reappear on their wireless channel; delay sensitive devices change the wireless channel along the hopping gateway. Thus, the traffic load and congestion in each wireless channel can be reduced improving transmission efficiency. The proposed approach's performance is evaluated by computer simulation and verified in terms of transmission efficiency.

Characteristic of wireless power transmission S-Parameter for a superconductor coil

  • Jeong, In-Sung;Jung, Byung-Ik;Choi, Hyo-Sang
    • Progress in Superconductivity and Cryogenics
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    • v.17 no.1
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    • pp.36-39
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    • 2015
  • Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency.

Characteristics of Wireless Power Transmission applying the superconducting coil (초전도 코일을 적용한 WPT 특성)

  • Jeong, In-Sung;Choi, Hyo-Sang
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.762-766
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    • 2013
  • Interest in Wireless Power Transmission (WPT) technology has been increasing worldwide recently. This trend is proved by commercialized products such as electric toothbrush, wireless razor, and wireless charger for mobile phone battery. Studies for enhancing the applicability of the technology have been continuously conducted. Currently the WPT technology is based on the technologies using microwave, inductively coupling, and magnetic resonance. In the meantime, development of the microwave-based WPT faces difficulty due to health hazards involved in the technology, and application of the WPT technology using inductively coupling is restricted by area due to the problem of transmission length. In comparison, the WPT technology using magnetic resonance draws attention in terms of efficiency and transmission length. In this study, the sending coil based on the WPT technology using magnetic resonance system was replaced with an HTS coil to enhance transmission efficiency. Since the HTS coil has a zero resistance, power transmission loss can be minimized. At the same time, size of the current density could be increased to 100 times or more than typical coils. In addition, through impedance matching of LC device, maximal resonance properties were induced and consequently, frequency selection quality characteristics or Q was enhanced. As a result, the WPT type using the HTS coil showed a longer transmission length and better transmission efficiency compared with the WPT type using typical coils.