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

• Journal of The Korean Society of Integrative Medicine
• /
• v.8 no.3
• /
• pp.133-142
• /
• 2020

Purpose : The purpose of this study was to investigate the differences in social quotient and sensory processing function between completed-toileting and incomplete-toileting children with autism spectrum disorder (ASD). We aims to provide a basis for the training of children with autism spectrum disorders. Methods : The subjects of this research were children with ASD, aged from 4 to 7, receiving sensory integration therapy at the H-Child Development Research Center in Busan, South Korea. After recruiting 30 parents who had children with ASD, we interviewed them and we divided their children into completed-toileting group and incomplete-toileting group based on the past researches. We assessed them using the Social Maturity Scale and Sensory Profile. Spearman correlation was used to analyze between the sensory processing score and social quotient. Mann-Whitney U test was used to compare the Sensory Profile scores of the two groups. Results : The social quotient was correlated with the sensory processing score in the most of component as for auditory processing, vestibular processing, touch processing, multisensory processing, orosensory processing, except for visual processing. The groups of completed-toileting and incomplete-toileting group showed statistically significant intergroup difference in sensory seeking, emotional reactive, oral-sensory sensitivity, and inattention/distractibility in the sensory factor region. No statistically significant difference from intergroup was observed in any modulation areas, nor in behavioral & emotional response domains. Conclusion : A significant intergroup difference was observed in the most of sensory processing areas, except for modulation areas and behavioral & emotional response domains. The result revealed that toileting is significantly correlated with sensory processing. Therefore, this study suggests that the sensory processing function should be considered in the toilet training of children with ASD.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.1
• /
• pp.69-73
• /
• 2011

In the defence wireless communications, conventional Anti-Jamming techniques(Frequency Hopping/Spread Spectrum or Direct Sequence/Spread Spectrum) are used to overcome a intentional interfering signals which are single/multitone or partial band jammer etc. DS/SS techniques is very strong on tone jamming signal but not to be on a partial band jammer. So FH/SS AJ performances are expected method of an substitution of DS/SS, however FH/SS could not have good performance on some BMTJ(Band Multi-tone Jammer). So this paper proposes FH-CSS (Frequency Hopped - Chirp Spread Spectrum) to get more robustness against jammers(BMTJ, PBNJ) and analyze the AJ performances.

• Journal of electromagnetic engineering and science
• /
• v.8 no.2
• /
• pp.41-46
• /
• 2008

A bandwidth and power efficient high speed ubiquitous sensor network(USN) for realizing a ubiquitous society is a great challenge for researcher community. In this paper we incorporate a cooperative transmission protocol within a special type of multi-code modulation to meet these requirements. Multi-code(Mc) modulation has been developed for high-speed data transmission over wireless channels. We proposed a new class of orthogonal codes for multi-code modulation which is an orthogonal subset of orthogonal codes(OSOC). Our proposed OSOC structure allows us to use only one relay to cooperate M nodes that effectively reduces the bandwidth and power requirement. This protocol is similar to spread-spectrum(SS) technique that can reduce both broad and narrow band jamming.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.12
• /
• pp.608-615
• /
• 2003

This paper describes an implementation of a DSP (Digital Signal Processor) controlled random carrier frequency modulation for the PWM inverter for acoustic noise reduction of induction motors. Real-time generation of the random variable and RPWM(Random PWM) along with the speed control was achieved by DSP TMS320C31. The experimental results show that the voltage and current harmonics are spread to a wide band area and the power spectrum of the acoustic switching noise was spread to create a more appealing, less annoying sound. Also, the speed response of the implemented method and the conventional method is nearly similar to each other from the viewpoint of the v/f constant control.

• ETRI Journal
• /
• v.28 no.1
• /
• pp.95-98
• /
• 2006

In this letter, a novel M-ary code-selected direct sequence (DS) ultra-wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M-ary code-selected direct sequence bipolar pulse amplitude modulation (MCSDS-BPAM) scheme. In this system, a particular DS code sequence is selected by the $log_2M$/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal-to-noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS-BPAM UWB system over an ideal AWGN channel and correlation receivers.

• Journal of Advanced Marine Engineering and Technology
• /
• v.18 no.2
• /
• pp.75-82
• /
• 1994

The existence of peroodic impulse noises in distribution line carrier (DLC) communication system is known to be the most serious obstacle for improving DLC communication quality in reliability and capacity. From the spectral points, impulse noises can be divided into baseband type and modulation type the noise width of whichs are much different each other. With each nose type, this study presents the basic characteristics in relation to what they originate from and how their spectrum properties are revealed. The baseband type impulse noise is normally caused from thyristor circuit running with low switching speed and the modulation type noise from the circuit of switching power supply. The base wave of modulation noise is shown to be the pulsuatic charging current to primary condenser in switching power circuit. The study result indicates also that placing the DLC carrier frequency away the band predominated by modulated noise especially from RCC type switching power circuit is very important in DLC design.

• Journal of the Optical Society of Korea
• /
• v.18 no.1
• /
• pp.15-22
• /
• 2014

We present a novel bandwidth measurement scheme for multimode optical fibers. Amplified spontaneous emission (ASE) radiation was utilized for a source of intrinsically modulated light with a wide modulation bandwidth. In our measurement scheme, the continuous-wave (CW) ASE light that passed through a multimode fiber (MMF) under test was analyzed by the fourth-order power with a high-speed photodetector and an electric spectrum analyzer. The modulation transfer function of the multimode fiber could be directly measured with the photoelectric spectra in the modulation frequency domain. The measurement result of our method was experimentally compared to that of the conventional measurement scheme based on the impulse response measurement. It has been found that our scheme provides a stable measurement means of MMF characterization that is suitable for the field testing due to the simplicity of the system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.2
• /
• pp.425-430
• /
• 2017

This paper presents a novel method for identification of FSK modulated radar signal. Three features which measure the number of frequency tones, the regularity of the frequency shifting, and the diversity of power spectrum of detected radar signal, are introduced. A Two-step combined maximum likelihood classifier was used to identify the details of the detected FSK signal; the modulation order and the use of Costas code. We attempted to divide FSK signal into binary FSK, ternary FSK, 8-ary FSK, and FSK with Costas code of length 7. The simulation results indicated that the proposed methods achieves an averaged identification accuracy was 99.93% at a signal-to-noise of 0 dB.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.1
• /
• pp.11-21
• /
• 2008