• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.786-791
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• 2009

This study focus on verification of the thermal efficiency of volumetric air receiver with $5kW_{th}$ Dish-type solar thermal system for high temperature uses by using numerical analysis compare with experimental data including shape change of absorber, direction of inlet and outlet. Porous material for radiation-thermal conversion used in former researches are substituted with the stainless steel wall installed along the spiral shaped flow path. Temperature variation and the flow change at the inside of the absorber has been analyzed by Star-ccm+ Version 3.02. Using the numerical model, the heat transfer characteristics of spiral type receiver for dish-type solar thermal systems are known and the thermal performance of the receiver can be estimated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.179-183
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• 2007

This paper is to implement a low power frequency Shift Keying(FSK) receiver using Xilinx System Generator. The receiver incorporates a 16 point Fast Fourier Transform(FFT) for symbol detection. The design units of the receiver are digital designs for better efficiency and reliability. The receiver functions on one bit data processing and supports data rates 10kbps. In addition CORDIC algorithm is used for avoiding complex multiplications while computing FFT, multiplication of twiddle factor is substituted by rotators. The design and simulation of the receiver is carried out in Simulink, then the simulink model is translated to a hardware model to implement FPGA using Xilinx System Generator and to verify performance.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.6
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• pp.286-295
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• 2006

This paper presents a design of a real-time software GPS receiver which runs on a PC. The software GPS receiver has advantages over conventional hardware based receivers in terms of flexibility and efficiency in application oriented system design and modification. In odor to reduce the processing time of the software operations in the receiver, a shared memory structure is used with a dynamic data control, and the byte-type IF data is processed through an Open Multi-Processing technique in the mixer and integrator which requires the most computational load. A high speed data acquisition device is used to capture the incoming high-rate IF signals. The FFT-IFFT correlation technique is used for initial acquisition and FLL assisted PLL is used for carrier tracking. All software modules are operated in sequence and are synchronized with pre-defined time scheduling. The performance of the designed software GPS receiver is evaluated by running it in real-time using the real GPS signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1488-1494
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• 2008

This paper is to design and implement a low power noncoherent BFSK receiver intended for future deep space communication using Xilinx System generator. The receiver incorporates a 16 point Fast Fourier Transform(FFT) for symbol detection. The design units of the receiver are digital design for better efficiency and reliability. The receiver functions on one bit data processing and supports main data rate 10kbps. In addition CORDIC algorithm is used for avoiding complex multiplications while computing FFT and multiplication of twiddle factor for low power is substituted by rotators. The design and simulation of the receiver is carried out in Simulink then the Simulink model is translated to the hardware model to implement FPGA using Xilinx System Generator and to verify performance.

• Solar Energy
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• v.12 no.1
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• pp.95-102
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• 1992

A small scale solar collector system composed of a Fresnel lens of $0.5m^2$ area as a solar concentrator and a compact fluidized-bed solar receiver was developed. Performance and temperature distribution in the fluidized bed receiver were measured using SiC for particles and air for working fluid. The maximum gas temperature was attained up to 1250K at this moment. In this study, energy efficiency achieved by the present experiment was high for the small scale solar collector system and compact receiver.

• Journal of Communications and Networks
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• v.12 no.6
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• pp.533-543
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• 2010

This paper proposes an orthogonal frequency division multiplexing (OFDM) waveform for the forward link of a fixed broadband satellite system. We focus on the synchronization tasks in the receiver. Our objective is to minimize the required overhead, in order to improve the spectral efficiency with regard to a single carrier waveform system. A non pilot aided algorithm is used for fine synchronization. It is preceded by a coarse synchronization stage, which relies on a limited overhead (short cyclic prefix associated to some pilots). The performance of the proposed receiver is assessed through simulation results.

• Smart Structures and Systems
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• v.3 no.1
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• pp.1-22
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• 2007

The energy efficiency of a self-powered wireless sensing system for pressure monitoring in injection molding is analyzed using Bond graph models. The sensing system, located within the mold cavity, consists of an energy converter, an energy modulator, and a ultrasonic signal transmitter. Pressure variation in the mold cavity is extracted by the energy converter and transmitted through the mold steel to a signal receiver located outside of the mold, in the form of ultrasound pulse trains. Through Bond graph models, the energy efficiency of the sensing system is characterized as a function of the configuration of a piezoceramic stack within the energy converter, the pulsing cycle of the energy modulator, and the thicknesses of the various layers that make up the ultrasonic signal transmitter. The obtained energy models are subsequently utilized to identify the minimum level of signal intensity required to ensure successful detection of the ultrasound pulse trains by the signal receiver. The Bond graph models established have shown to be useful in optimizing the design of the various constituent components within the sensing system to achieve high energy conversion efficiency under a compact size, which are critical to successful embedment within the mold structure.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.739-746
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• 2017

Orthogonal frequency division multiplexing(OFDM) systems have many advantages. However, OFDM systems are much affected by a nonlinear distortion because those systems have a high peak to average power ratio(PAPR) value. A selected mapping technology was suggested to reduce a PAPR value. The technology does not have data loss but receivers need side information to know modified phase sequence. Therefore, side information causes decreased a transmission efficiency. In this paper, we suggest a blind SLM receiver using a cross correlation technology. This receiver does not require side information. The proposed blind SLM receiver calculates sums of cross-correlation between transmitted pilot signals multiplied by each phase sequence and received pilot signals. So, this receiver detects side information which has a maximum sum cross-correlation value. We compared our proposed SLM receiver to a conventional blind SLM receiver through bit error rate(BER) and side information error rate(SIER) performances. Simulation results show that the proposed SLM receiver has improved BER and SIER performances than the conventional SLM receiver.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.62-67
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• 2009

This paper describes the characteristics of scroll type stirling engine receiver. Scroll type stirling engine operated scroll compressor and expander instead of piston. Pass dimension of the receiver was $14(W){\times}14(H)$ mm and total pass length was 5,049 mm. External dimension of the receiver was $300{\times}300mm$. The experimental facility consisted of parabolic dish concentrator, compressor to supply air, triplex air filter, and flowmeter. In this study, basic experimental conditions were set at a inlet pressure of 5 bar and volume flow rate of $25m^3/hr$. As a result, air temperature in receiver at each measuring position of point 1, 2, 3 were $241^{\circ}C$, $465^{\circ}C$, and $542^{\circ}C$ respectively at inlet pressure of 5.5 bar and volume flow rate of $24.6m^3/hr$. As DNI increasing, heat transfer coefficient of the receiver changed from $695W/m^2K$ to $827W/m^2K$. Average heat transfer coefficient of receiver in the experiment was $798W/m^2K$. In addition, receiver efficiency became about 83%.