• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.66-72
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• 2009

In this paper, an efficient frequency offset synchronization structure for OFDM(Orthogonal Frequency Division Multiplexing) is proposed. Conventional CORDIC(Coordinate Rotation Digital Computer) algorithm for frequency offset synchronization utilizes two CORDIC hardware i.e., one is vector mode for phase estimation, the other is rotation mode for compensation. But proposed structure utilizes one CORDIC hardware and divider. Through simulation, it is shown that hardware implementation complexity is reduced compared with conventional structures. The Verilog-HDL coding and front-end chip implementation results for the proposed structure show 22.1% gate count reduction comparison with those of the conventional structure.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.118-125
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• 2008

In this paper, an efficient frequency offset synchronization structure for OFDM(Orthogonal Frequency Division Multiplexing) is proposed. Conventional CORDIC(Coordinate Rotation Digital Computer) algorithm for frequency offset synchronization utilizes two CORDIC hardware i.e., one is vector mode for phase estimation, the other is rotation mode for compensation. But proposed structure utilizes one CORDIC hardware and divider. Through simulation, it is shown that hardware implementation complexity is reduced compared with conventional structures. The Verilog-HDL coding and front-end chip implementation results for the proposed structure show 22.1% gate count reduction comparison with those of the conventional structure.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.121-127
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• 2024

In this paper, FEM (Front-End Module) MMIC, a key component for the application of the satellite communication terminal transmission and reception module of the multi-phase array structure, was designed and verified as a single chip by designing the Power Amplifier (PA) and the Low Noise Amplifier (LNA). It was manufactured using the GaAs PP10 (100nm) process, a compound semiconductor process from Win-semiconductors, and the operating frequency band of 7.2-10.5GHz operation, output 1W, and noise index of 1.5dB or less were secured using a dedicated test board. The developed FEM MMIC can be used as a single chip, and the components PA and LNA can also be used as each device. The developed device will be used in various applications of Minsu/Gunsu using the X band and the localization of overseas parts.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1519-1525
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• 2009

This paper presents a novel passive converter for single phase SRM. The proposed passive converter has additional passive power circuit which is consisted by three diodes and one capacitor in the front-end of conventional asymmetric converter to supply a high negative bias during demagnetization. The high negative bias can reduce the demagnetization time and negative torque from tail current in single phase SRM. So, It can extend positive torque region by the extended turn-off position. In this paper, the structure and operating modes of a novel passive converter are introduced with mathematical model. The proposed single phase SRM using passive converter is verified by the computer simulation and experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.13-21
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• 2005

I consider the structure of steady wave system which is admitted by the continuum equations for materials that undergo phase transformations with exothermic chemical reaction. In particular, the dynamic phase front structures between liquid and gas phases, and solid and liquid phases are computationally investigated. Based on the one-dimensional continuum shock structure analysis, the present approach can estimate the nano-width of waves that are present in combustion. For illustration purpose, n-heptane is used in the evaporation and condensation analysis and HMX is used in the melting and freezing analysis of energetic materials of interest. On-going effort includes extension of this idea to include broad range of liquid and solid fuels, such as rocket propellants.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.4
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• pp.1-5
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• 2011

A new code structure for spectral-amplitude-coding optical CDMA based upon reconstructed modified double weight codes is proposed. The newly proposed code possesses ideal cross-correlation properties. By using fiber Bragg grating(FBG) in front of optical decoder, we can get the improved performance of the proposed system with the consideration of phase-induced intensity noise(PIIN).

• Journal of Power Electronics
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• v.7 no.1
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.31-34
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• 2002

Imaging techniques using x-ray beam at high energies (>6KeV) such as contact radiography, projection microscopy, and tomography have been used to nondestructively discern internal structure of objects in material science, biology, and medicine. This paper introduces the x-ray micro-imaging method using 1B2 micro-probe line of PAL (Pohang Accelerator Laboratory). Cross-sectional information on low electron density materials can be obtained by probing a sample with coherent synchrotron x-ray beam in an in-line holography setup. Living organism such as plants, insects are practically transparent to high energy x-rays and create phase shift images of x-ray wave front. X-ray micro-images of micro-bubbles of $20\~120\;{\mu}m$ diameter in an opaque tube were recorded. Clear phase contrast images were obtained at Interfaces between bubbles and surrounding liquid due to different decrements of refractive index.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2039-2044
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• 2009

The PSK carrier signal recovery circuit using multi-layer coupled line was analyzed and designed. The fabricated carrier recovery 6 port element with multi-layer coupled line structure gets the simple architecture. It is possible to implement the carrier signal recovery circuit of the same structure with the multi-layer six port phase correlator of the direct receiver front-end. Based on the analysis of RML carrier recovery circuit using the multi-layer coupled line 6-port phase correlator, the multi-layer coupled line carrier signal recovery structure for multi-mode coherent demodulation was proposed. The fabricated multi-layer coupled line carrier signal recovery circuit for quadrature phase shift-keying shows a good carrier signal characteristic with a constant phase and phase error below ${\pm}3o$.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.4
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• pp.17-24
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• 2014

In this paper, we propose a CMOS FM RX front-end structure with an automatic tunable input matching network and implement it using a 65nm CMOS technology. The proposed FM RX front-end is designed to change the resonance frequency of the input matching network at the low noise amplifier (LNA) according to the channel frequency selected by a phase-locked loop (PLL) for maintaining almost constant sensitivity level when an embedded antenna type with high frequency selectivity characteristic is used for FM receiver. The simulation results of implemented FM front-end show about 38dB of voltage gain, below 2.5dB of noise figure, and -15.5dBm of input referred intercept point (IIP3) respectively, while drawing only 3.5mA from 1.8V supply voltage including an LO buffer.