• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.529-534
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• 2002

Recently, As the higher frequency in clock of digital system being demanded and the density of circuits gets high for purpose of making light and minimizing system, the study for solution of digital signal distortion being interested. In this paper, the distortion of square pulse caused by dispersion as it propagates along a single microstrip line and crosstalk between lines on the Multi-Transmission Lines (MTL) is investigated. The dispersion and crosstalk of pulse signals is analyzed regarding to the structure of transmission line such as relative permittivity, substrate height, strip width of the microstrip line and pulse width of signal pulse.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권1호
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• pp.40-44
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• 2006

In this paper, the distortion characteristics of an electrical pulse which has a rise/fall time due to the dispersion and the reflection, on nonuniform tapered microstrip lines has investigated in time domain. The transmission characteristics on uniform microstrip lines in time domain had represented already, but the results for the nonuniform tapered microstrip lines not represented yet. We investigated the transmission characteristics for pulse signal on the nonuniform tapered microstrip lines, and the result applied to design of wide band impedance matching circuit in design of MMIC. The voltage and current transfer functions are shown for the tapered line. The dispersion and distortion obtained by using these transfer functions are represented for the nonideal square pulse.

• 센서학회지
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• 제25권1호
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• pp.71-78
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• 2016

PPG signal measured by pulse oximeter can measure pulse and the oxygen saturation of arterial blood. But the PPG signal is distorted by finger movement or other movement in the body. To detect pulse from the PPG signal with motion artifact, we use band pass filter(BPF), Independent component analysis(ICA) and nonlinear autocorrelation(NAC). BPF is used to remove DC component and high frequency noise in the PPG signal with motion artifacts. ICA is used to separate pulse signal and motion artifact. However, pulse signal separated by ICA have no choice but to accompany signal distortion because pulse signal and motion artifact are not completely independent. So, we use nonlinear autocorrelation to emphasize the pure pulse signal from the distorted signal.

• Journal of electromagnetic engineering and science
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• 제3권2호
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• pp.79-85
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• 2003

In this paper, we investigated the degree of compensation for distorted optical pulse of wavelength division multiplexed(WDM) channel with initial frequency chirp generated in optical transmitter. The WDM channel signal distortion is due to chromatic dispersion, self phase modulation(SPM) and cross phase modulation(XPM) in fiber. The considered system is 3 ${\times}$ 40 Gbps intensity modulation direct detection(IM/DD) WDM transmission systems, which adopted mid-span spectral inversion(MSSI) as compensation method. We confirmed that the effect of initial frequency chirp on compensation for signal distortion due to a SPM is gradually decreased as a dispersion coefficient of fiber becomes gradually small. But, in the aspect of a compensation for signal distortion due to both SPM and XPM, the effect of initial frequency chirp on compensation is gradually decreased as a dispersion coefficient of fiber becomes gradually large.

• Journal of Power Electronics
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• 제16권1호
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• pp.388-397
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• 2016

An error-compensated pulse width modulator (ECPWM) is proposed to improve the baseband harmonic performance and the switching loss of voltage source inverters (VSIs). Selecting between harmonic distortion and switching loss is a design tradeoff in the conventional space vector pulse width modulation. In this work, an accumulated difference in produced and desired phase voltages is considered to adjust the reference signal. This mechanism can compensate for the voltage error in the previous carrier period. With error compensation every half-carrier period, the proposed ECPWM allows one-half reduction in carrier frequency without scarifying baseband harmonic distortion. The proposed modulator is applied to a three-phase VSI with R-L load and a motor-speed-control system for experiments. The measured efficiency and operating temperature of switches confirm the effectiveness of the proposed scheme.

• 한국정보통신학회논문지
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• 제17권8호
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• pp.1755-1760
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• 2013

본 논문에서는 마이크로스트립 선로를 따라 펄스가 전송될 때 분산에 의한 펄스의 왜곡특성을 시간영역에서 해석 하였다. 전송선로의 구조, 유전율에 따른 분산특성을 비교 분석하였고, 구형펄스와 가우시안 펄스에 대해 펄스의 폭과 진폭, 그리고 전송속도에 따라 분산특성을 분석하였다. 구형 펄스의 경우 더 높은 고차 고조파 성분을 가지고 있기 때문에 이에 따른 저차 고조파 성분과의 위상 속도 차이가 선로를 따라 진행함에 따라 급격히 나타나서 분산이 심하게 나타났다. 본 연구의 결과는 MIC 또는 MMIC를 설계할 때 펄스전송에서 왜곡을 최소화하기 위해 펄스 폭, 선로의 폭, 기판의 높이 그리고 유전율을 결정하는데 유용하게 사용될 것이다.

• 센서학회지
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• 제26권2호
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• pp.141-147
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• 2017

A pressure sensor in pulse measurement system is a core component for precisely measuring the pulse waveform of radial artery. A pulse sensor signal that measures the pulse wave in contact with the skin is affected by the temperature difference between the ambient temperature and skin surface. In this study, we found experimentally that the signal changes of the pressure sensors and a temperature sensor were caused by the temperature of the wrist surface while the pressure sensor was contacted on the skin surface for measuring pulse wave. To observe the signal change of the pulse sensor caused by temperature increase on sensor surface, Peltier device that can be kept at a set temperature was used. As the temperature of Peltier device was kept at $35^{\circ}C$ (the maximum wrist temperature), the device was put on the pulse sensor surface. The temperature and pressure signals were obtained simultaneously from a temperature sensor and six pressure sensors embedded in the pulse sensor. As a result of signal analysis, the sensor pressure was decreased during temperature increase of pulse sensor surface. In addition, the signal difference ratio of pressure and temperature sensors with respect to thickness of cover layer in pulse sensor was increased exponentially. Therefore, the signal of pressure sensor was modified by the compensation equation derived by the temperature sensor signal. We suggested that the thickness of cover layer in pulse sensor should be designed considering the skin surface temperature.

• 한국자기공명학회논문지
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• 제26권4호
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• pp.51-58
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• 2022

The baseline flattened NMR spectrum has been achieved by several methodologies including pulse manipulation with a series of phase cycling. The background signal inherent in the probe is also main source of baseline distortion both in solution and solid NMR. The simple direct polarization with 90° pulse flipping the magnetization from the z-axis onto the receiver coil requires the strong rf pulse enough to encompass the wide frequency range to excite the resonance of interest nuclei. Albeit the perfect polarization 90° pulse, the signal from the unwanted magnetic fields such as background signal can not be completely suppressed by suitable phase cycling. Moreover, slowly baseline wiggling signal from the low 𝛾 nuclei is not easy to eliminate with multiple pulse manipulation. So there is still need to contrive the new scheme for that purpose in an adroit manner. In this article new triple pulse excitation schemes for TIP and modified DEPTH pulse sequence are analytically examined in terms of arbitrary phase and flip angle of pulse. The suitable phase cycling for these pulse trains is necessary for the good sensitivity and resolution of the spectrum. It is observed that the ¹³C sensitivity TIP experiment is almost equal to the CP/MAS with modified DEPTH sequence, both of which are applicable to both solid and solution state NMR.

• 대한의용생체공학회:의공학회지
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• 제35권6호
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• pp.234-241
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• 2014

This study was designed to investigate the effects of stimulation intensity and inter-electrode distance on the parameters of the measured sensory nerve signal. 30 healthy subjects participated in this study. Sensory nerve signals were elicited by four different pulse amplitudes, i.e., 3, 6, 9, 12 mA, with the pulse width fixed at $500{\mu}s$. The sensory nerve signals elicited by the four different pulse amplitudes were measured by four different inter-electrode distances (20, 30, 40, and 50 mm). We extracted four parameters (pulse amplitude, pulse width, pulse area, and latency time from stimulation) from the sensory nerve signals. The measured pulse amplitude and pulse width were increased when the measuring inter-electrode distance was increased while the stimulating pulse amplitude was fixed. The measured pulse amplitude was saturated with the stimulating pulse amplitudes of over 6 mA while measuring inter-electrode distance. Under the same condition, measured pulse width was increased, and sensory nerve signal was initiated early. Sensory nerve signals, specially those of pulse amplitude, were distorted by a differential amplification method that commonly measures the human body signal. The experimental results indicate that the differential amplification method is required to be replaced when measuring nerve signals. Our observations suggested that the hyperpolarization of the action potential of the sensory nerve signal for preventing distortion could be used to clarify the correlation between the parameters of the sensory nerve signals and quantification of sensations.

• 한국전자파학회논문지
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• 제21권6호
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• pp.553-563
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• 2010

본 논문에서는 UWB 대역에서 최적 임펄스 신호 전송을 위한 테이퍼 슬롯 안테나(Tapered Slot Antenna: TSA) 설계에 대해 연구하였다. UWB 대역에서 동작하는 TSA는 end-fire 특성을 갖는 광대역 안테나로, 펄스 전송을 위한 IR-UWB(Impulse Radio Ultra-Wide Band) 시스템에 적합하다. 지향성 특성을 갖는 테이퍼 슬롯 안테나는 UWB 대역에서 손실이 적고, 임펄스 전송시 최소 에러를 가져야 한다. 전송되는 펄스 왜곡을 최소로 하기 위해 테이퍼 슬롯 안테나 급전부를 구성하는 광대역 임피던스 변환기와 microstrip/slotline 천이부 설계에 대해 연구하였으며, 설계된 테이퍼 슬롯 안테나에 대한 펄스 충실도는 전자기파에 대한 시간 영역 분석이 가능한 CST를 이용한 FDTD(Finite-Difference Time-Domain) 시뮬레이션과 펄스 상관식 유도를 통해 계산하였으며, 제작된 안테나에 대해 두 안테나를 0.5 미터 이격시킨 두 안테나 사이에서 약 93.89 % 정도의 양호한 결과를 얻을 수 있었다. 또한 chirp Z-변환 알고리즘을 유도를 통해, 나노초 이하의 펄스 신호에 대해 zoom-in 기능을 부여함으로써 펄스 신호에 대한 왜곡, 지연 및 분산 특성 등의 분석이 가능하다.