• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.6
• /
• pp.313-316
• /
• 2006

A method for evaluation of the linearity of both the ratio error and phase angle error in the current transformer(CT) comparison measurement equipment has been developed by employing the standard resistors with negligible AC-DC resistance difference less than $10^{-5}$. The non-reactive standard resistors for the linearity check of the system are used as the external burden connected with the secondary of CT under test. These burdens consist of nine standard resistors, with the nominal resistance of $0.01{\Omega},\;0.1{\Omega},\;0.2{\Omega},\;0.4{\Omega},\;0.6{\Omega},\;1{\Omega},\;2{\Omega},\;4{\Omega}$, and $10{\Omega}$. For linearity check, the developed method has been applied in the CT comparison measurement equipment belonging to the industry.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.443-447
• /
• 1999

The AC drive systems of a voltage source inverter and an induction motor. The inverter non linearity caused by the turn on/off time dependency of the current level in the switching IGBT is described in the first part of this paper. To improve the low-speed drive characteristics, accurate applied voltage calculation is proposed under considerations of the compensations for the quantization error in the digital controller, the forward voltage drop of switching drives and the dead time of the inverter. The experimental studies show the improved drive characteristics.

• Structural Engineering and Mechanics
• /
• v.44 no.3
• /
• pp.339-361
• /
• 2012

Large amplitude free vibration and thermal post-buckling of shear flexible Functionally Graded Material (FGM) beams is studied using finite element formulation based on first order Timoshenko beam theory. Classical boundary conditions are considered. The ends are assumed to be axially immovable. The von-Karman type strain-displacement relations are used to account for geometric non-linearity. For all the boundary conditions considered, hardening type of non-linearity is observed. For large amplitude vibration of FGM beams, a comprehensive study has been carried out with various lengths to height ratios, maximum lateral amplitude to radius of gyration ratios, volume fraction exponents and boundary conditions. It is observed that, for FGM beams, the non-linear frequencies are dependent on the sign of the vibration amplitudes. For thermal post-buckling of FGM beams, the effect of shear flexibility on the structural response is discussed in detail for different volume fraction exponents, length to height ratios and boundary conditions. The effect of shear flexibility is observed to be predominant for clamped beam as compared to simply supported beam.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.4
• /
• pp.1-9
• /
• 2009

In this paper, a small area 12-bit 300MSPS CMOS Digital-to-Analog Converter(DAC) is proposed for display systems. The architecture of the DAC is based on a current steering 6+6 segmented type, which reduces non-linearity error and other secondary effects. In order to improve the linearity and glitch noise, an analog current cell using monitoring bias circuit is designed. For the purpose of reducing chip area and power dissipation, furthermore, a noble self-clocked switching logic is proposed. To verify the performance, it is fabricated with $0.13{\mu}m$ thick-gate 1-poly 6-metal N-well Samsung CMOS technology. The effective chip area is $0.26mm^2$ ($510{\mu}m{\times}510{\mu}m$) with 100mW power consumption. The measured INL (Integrated Non Linearity) and DNL (Differential Non Linearity) are within ${\pm}3LSB$ and ${\pm}1LSB$, respectively. The measured SFDR is about 70dB, when the input frequency is 15MHz at 300MHz clock frequency.

• Clinical Nutrition Research
• /
• v.11 no.3
• /
• pp.214-227
• /
• 2022

Despite controversies, no earlier study has systematically summarized findings from earlier studies on the effect of artichoke supplementation on blood pressure. Therefore, current systematic review and meta-analysis was done on the effect of artichoke supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in adults. Five databases were searched from inception to January 2022 using relevant keywords. All randomized clinical trials investigating the impact of oral artichoke supplementation on any of the blood pressure parameters including SBP or/and DBP were included. Out of 1,507 citations, 7 trials that enrolled 472 subjects were included. Artichoke supplementation resulted in significant reduction in SBP (weighted mean difference [WMD], -2.01 mmHg; 95% confidence interval [CI], -3.78, -0.24; p = 0.026) and DBP (WMD, -1.45 mmHg; 95% CI, -2.81, -0.08; p = 0.038). Greater effects on SBP were detected in trials using ≤ 500 mg artichoke, lasted > 8 weeks, participants aged < 50 years' old and sample size ≤ 70. There was also a similar impact of artichoke on DBP. However, significant non-linear associations were found between artichoke supplementation dosage and study duration with both SBP (for dosage: p_{non-linearity} = 0.002, for duration: p_{non-linearity} = 0.016) and DBP (for dosage: p_{non-linearity} = 0.005, for duration: p_{non-linearity} = 0.003). We found a significant reduction in both SBP and DBP following artichoke supplementation in adults. It could be proposed as a hypotensive supplement in hypertension management.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.2C
• /
• pp.191-199
• /
• 2006

In this paper, we propose a method to implement a predistorter of the $rho$-th order inverse filter structure to prevent signal distortion and spectral re-growth due to the high PAPR (peak-to-average ratio) of the OFDM signals and the non-linearity of high-power amplifiers. We model the memory-less non-linearity of the high-power amplifier with a polynomial model and utilize the inverse of the model, the $rho$-th order inverse filter, for the predistorter. Once the non-linearity is modeled with a polynomial, since we can determine the $rho$-th order inverse filter only with the coefficients of the polynomial, large memory is not required. To update the coefficients of the non-linear high-power amplifier model, we can use LMS or RLS algorithms. The convergence speed is high since the number of coefficients is small, and the computation is simple since manipulation of complex numbers is not necessary.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.10 no.1
• /
• pp.107-115
• /
• 2007

In this paper we confirm the disappearance of dynamic lock-in simply by increasing the dither noise magnitude of the ring laser gyroscope by numerical and experimental method. After that, we numerically study the relation between the dither noise forms and scale factor non-linearities by comparing those of the two case outputs which are individually generated by operating with the two types of dither noise forms. The first one is the simple form composed of consecutive alternations of the random increasing and decreasing parts but maximum and minimum dither envelopes are scarcely changeable. And the second one is similar to the first one but maximum and minimum dither envelopes are randomly changable. As a result, we find that the scale factor non-linearity could be improved by the second one. And we confirm those results by experimental measurements.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.5
• /
• pp.30-36
• /
• 2012

A new BIST(Built-In Self-Test) scheme to test ADC(Analog-to-Digital Converter) with a transition detector is proposed. The proposed BIST is able to replaces histogram method, the most popular approach in static testing of ADC. With a ramp signal as an input test stimulus, the proposed BIST calculates ADC's static parameters such as offset, gain, INL(Integral Non-Linearity) and DNL(Differential Non-Linearity). The three detectors in the proposed BIST can deal with a transient zone problem, a phenomenon due to random noise in real test environments and are cost efficient at various acceptable ranges determined as a test spec. The simulation results validate that our method performs accurate static test and show the reduction of the hardware overhead.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.999-1004
• /
• 2004

A numerical method and algorithms is proposed to perform optimization of non-linear response structures. An analytical and numerical method based finite element method is also proposed for the transformation of non-linear response into linear response. Loads transformed from this method are defined as the equivalent linear loads. With the loads and the transformed response, linear static optimization is performed for nonlinear response structure with geometric and/or material non-linearity. The results of the optimization are compared with them of typical non-linear response optimization using finite difference method. The proposed method is very efficient and derives good solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.888-891
• /
• 2003

This paper describes on the fabrication and characteristics of micro ceramic thin-film type pressure sensors based on Ta-N strain-gauges for high-temperature applications. The Ta-N thin-film strain-gauges are deposited onto thermally oxidized Si diaphragms by RF sputtering in an argon-nitrogen atmosphere($N_2$ gas ratio: 8 %, annealing condition: $900^{\circ}C$, 1 hr.), Patterned on a wheatstone bridge configuration, and use as pressure sensing elements with a high stability and a high gauge factor. The sensitivity is $1.097{\sim}1.21mV/V.kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS. The fabricated pressure sensor presents a lower TCR, non-linearity than existing Si piezoresistive pressure sensors. The fabricated micro ceramic thin-film type pressure sensor is expected to be usefully applied as pressure and load sensors that is operable under high-temperature environments.