• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.10
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• pp.7-13
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• 2010

A compact phase interpolator (PI) based spread spectrum clock generator (SSCG) for electromagnetic interference (EMI) reduction is presented. The proposed SSCG utilizes a digitally controlled phase interpolation technique to achieve triangular frequency modulation with less design complexity and small power and area overhead. The novel SSCG can generate the system clock with a programmable center-spread spectrum range of up to +/- 2 % at 200 MHz, while maintaining the clock duty cycle ratio without distortions. The PI-based SSCG has been designed and evaluated in 0.18-um 1.8-V CMOS technology, which consumes about 5.0 mW at 200MHz and occupies a chip size of $0.092mm^2$ including a DLL.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.152-161
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• 2017

The CBTC(Communication based Train Control) system employed on 2.4GHz ISM band adopt the IEEE802.11.x standard. Therefor communication time delay, distortion and data losses will be produced. To overcome these problems, CPSK(Continuous Phase shift keying) modulated DS/SS(Direct Sequence Spread Spectrum) transmitter with 908MHz carrier frequency is proposed. Through the eye diagram and scatter diagram the performance is analysed. And the phase noise characteristic of the local oscillator is measured about 60dBc/Hz, this means that the phase noise performance is very good compared to the signal. Reference frequency suppression of the 2nd local oscillator is 50dB below compared to the signal. Through the polarities of the complementary signal equally probable, the line spectrum of the output spectrum is eliminated. The nonlinear effects which introduce the spectral spreading or spectral regeneration is reduced remarkably.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.4
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• pp.42-51
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• 2003

In this paper, we are going to analyze on relation of an output spectrum along phase distortion of power amplifier in wireless LAN system, and then considered an ACPR characteristic of power amplifier and consideration of an OFDM method for this. Also, we did implementation for OFDM modulation and transmission section of an IEEE 802.11a standard to have transmission speed of the maximum 54Mbps in order to know an OFDM modulation method and relation of non-linear characteristic of power amplifier. The non-linear characteristic of power amplifier did modeling with AM-to-AM and AM-to-PM, and we analyzed an output spectrum characteristic along phase distortion composed input signal supply for power amplifier. When output spectrum analysis results phase distortion increased, and an AM-to-PM characteristic of power amplifier in 5 degrees, the output spectrum was satisfied with a demand spectrum in P1 dB, but 10-20 degrees were able to confirm what cannot be satisfied with a demand spectrum in phase distortion. Also, an output spectrum of power amplifier by frequency re-growth generated by a non-linear characteristic of power amplifier did not satisfied in P1dE. therefore, a back-off value was requested according to an AM-to-PM distortion degree, and smaller back-off value were able to know what demand became in case of modulation section that used OFDM.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.984-996
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• 2014

In this paper, optimal sensing time allocation for adaptive multiband spectrum sensing-transmission procedure is investigated. The sensing procedure consists of an exploration phase and a detection phase. We first formulate an optimization problem to maximize the throughput by designing not only the overall sensing time, but also the sensing time for every stage in the exploration and detection phases, while keeping the miss detection probability for each channel under a pre-defined threshold. Then, we transform the initial non-convex optimization problem into a convex bilevel optimization problem to make it mathematically tractable. Simulation results show that the optimized sensing time setting in this paper can provide a significant performance gain over the previous studies.

• Korean journal of food and cookery science
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• v.2 no.2
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• pp.16-20
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• 1986

The major pungent component from Korean radish roots was purified by reverse phase high performance liquid chromatography (RPHPLC), and characterized as 4-methylthio-3-butenyl isothiocyanate on the basis of the sensory test (pungency), UV spectrum and mass spectrum analysis. The purified isothiocyanate moved as a single peak(retention time, 5.2 min) in RP-HPLC analysis, and as a single spot(Rf, 0.9) in TLC analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.141-148
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• 2006

This study describes a generation of artificial earthquake wane compatible with seismic design spectrum. In seismic response analysis of building structures, the input ground accelerations have considerable effect on dynamic characteristics of structures. Therefore, it is important to properly select input ground motions for seismic response analysis. In this paper, the artificial earthquake wave are generated according to previously recorded earthquake waves in past earthquake events. The artificial wave have identical phase angles to the recorded earthquake wane, and their overall response spectra are compatible with seismic design spectrum with 5% of critical viscous damping. Each simulated earthquake wave has a identical phase angles to the original recorded ground acceleration, and match to design response spectra in the range of period from 0.02 to 10.0 seconds. It is concluded that the artificial earthquake waves simulated in this paper ate applicable as input ground motions for a seismic response analysis of building structures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.617-623
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• 2013

Accurate prediction of the radiated noise is important to reduce the noise of the washing machine. It is also necessary to predict the excitation force accurately because excitation force can induce noise. In order to predict the excitation force acting on the washing machine, this paper conducts source identification method by use of phase reference spectrum. In this method, the transfer function between the cabinet and the motor through FEM and the measured response from the surface of the cabinet is used. The analysis of the radiation noise from the identified exciting force has been investigated. The comparison between the predicted SPL and the measured SPL at 1m apart from the front side of the washing machine showed good tendency.

• Journal of Powder Materials
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• v.9 no.5
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• pp.341-345
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• 2002

Nanoparticles of $Fe_2O_3$ with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of $\gamma-Fe_2O_3$ and $\alpha-Fe_2O_3$ in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk $\gamma-Fe_2O_3$. The low value of coercivity and saturation magnetization indicate that the $\gamma-Fe_2O_3$ phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk $\gamma-Fe_2O_3$ and $alpha-Fe_2O_3$. A quadrupole line on the center of spectrum represents of superparamagnetic phase of $\gamma-Fe_2O_3$ with a mean particle size of 7 nm or below.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.42-49
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• 2007

This paper implements RFID(radio-frequency identification)System to which the system was apply SS(Spread Spectrum) method. The system designed by using the algorithm for microprocessor with PLL of the receiver, PN spread, modulation and demodulation of the transceiver, and transistor amplifier for the output of stabilized BPSK (Binary Phase Shift Keying) signal. furthermore, it reduced the interference of the signal by designing the micro-strip narrow banded patch antenna, which is convenient for printing and producing, and decreased the volume of filter size in the system. It is also designed for the lower powered system with the possible application to UHF band of $860\sim930MHz$ for the international standard frequency band, which is the quota share of RFID distribution system.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.293-304
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• 2020

In this paper, various modulation techniques, including the legacy Global Navigation Satellite System (GNSS) signal modulation techniques, are introduced and the spectral characteristics and correlation characteristics of signals with various modulation techniques are analyzed based on numerical simulation. With the development of various GNSS services, the limited frequency band has become increasingly saturated, and issues of interoperability and compatibility have emerged in the new GNSS design. Since the efficient allocation of frequency resources is closely related to spectrum design, modulation techniques are one of the important signal design parameters of new signal design. Signal modulation techniques are closely related to various figure of merits (FoMs) as well as spectrum characteristic, and in some cases there is a complicated trade-off between FoMs. Thus, the FoMs associated with modulation technology should be analyzed and the best signal candidates should be chosen carefully via the trade-off analysis for FoMs. In this paper, we define the modulation technique based on Phase Shift Keying (PSK), Binary Offset Carrier (BOC) and Continuous Phase Modulation (CPM) for the design of KPS signals, and the FoMs of signals in terms of spectrum and correlation function are evaluated. Signals with various modulation techniques are implemented through a numerical simulation, and the relevant FoMs are analyzed.