• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.3
• /
• pp.456-463
• /
• 2021

In this paper, Ultra Wide-Band(UWB) radar sensor is employed to detect flying drones and avoid collision in dense clutter environments. UWB signal is preferred when high resolution range measurement is required for moving targets. However, the time varying motion of flying drones may increase clutter noises in return signals and deteriorates the target detection performance, which lead to the performance degradation of anti-collision radars. We adopt a dynamic clutter suppression algorithm to estimate the time-varying distances to the moving drones with enhanced accuracy. A modified Constant False Alarm Rate(CFAR) is developed using an adaptive filter algorithm to suppress clutter while the false detection performance is well maintained. For this purpose, a velocity dependent CFAR algorithm is implemented to eliminate the clutter noise against dynamic target motions. Experiments are performed against flying drones having arbitrary trajectories to verify the performance improvement.

• Journal of IKEEE
• /
• v.27 no.4
• /
• pp.518-523
• /
• 2023

The diagnosis of Inter Turn Short Circuits (ITSC) in induction motors is critical due to the escalating severity of faults resulting from even minor disruptions in the stator windings. However, diagnosing ITSC presents significant challenges due to similarities in noise and losses shared with 3-phase induction motors. Although artificial intelligence techniques have been explored for efficient diagnosis, practical applications heavily rely on model-based methods, necessitating further research to enhance diagnostic performance. This study proposed a diagnostic method applied the Clarke Transformation approach, focusing solely on current components while disregarding changes in rotating flux. Experimental results conducted over a 30-minute period, encompassing both normal and ITSC conditions, demonstrate the effectiveness of the proposed approach, with FAR(False Accept Rates) of 0.2% for normal-to-ITSC FRR(False Rejection Rates) and 0.26% for ITSC-to-normal FRR. These findings underscore the efficacy of the proposed approach.

• Progress in Superconductivity
• /
• v.5 no.1
• /
• pp.50-54
• /
• 2003

We have fabricated $∂^2$$B_{z}$ /$∂x^2$ type planar gradiometers and studied their properties in operation under various field conditions. $YBa_2$$Cu_3$$O_{7}$ film was deposited on $SrTiO_3$ (100) substrate by a pulsed laser deposition (PLD) system and patterned into a device by the photolithography with ion milling technique. The device consists of 3 pickup loops designed symmetrically Inner dimension and the width of the square side loops are 3.6 mm and 1.2 mm, respectively, and the corresponding dimensions of the center loop are 2.0 mm and 1.13 mm. The length of baseline gradiometer is 5.8 mm. Step-edge junction width is 3.0 $\mu\textrm{m}$ and the hole size of the SQUID loop is 3 $\mu\textrm{m}$ ${\times}$ 52 $\mu\textrm{m}$. The SQUID inductance is estimated to be 35 pH. The device was formed on a 20 mm ${\times}$ 10 mm substrate. We have tested the behavior of the device in various field conditions. The unshielded gradiometer was stable under extremely hostile conditions on a laboratory bench. Noise level 0.45 pT/$\textrm{cm}^2$/(equation omitted)Hz and 0.84 pT/$\textrm{cm}^2$/(equation omitted)Hz at 1 Hz for the shielded and the unshielded cases, which correspond to equivalent field noises of 150 fT/(equation omitted)Hz and 280 fT/(equation omitted)Hz, respectively. In spite of the short baseline of 5.8 mm, the high common-mode-rejection-ratio of the gradiometer, $10^3$, allowed us to successfully record magnetocardiogram of a human subject, which demonstrates the feasibility of the design in biomagnetic studies.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.6
• /
• pp.175-181
• /
• 2019

For the purpose of Application to the small radar sensor, the MMIC Chip, which is the core component of the W-band, was designed in Korea according to the characteristics of the transceiver and manufactured by 0.1㎛ GaAs pHEMT process, and compared with the MMIC chip purchased overseas. The noise figure of low noise amplifier, insertion loss of the switch and image rejection performance of the down-converted mixer MMIC chip showed better characteristics than those of commercial chips. The MMIC chip developed in domestic was applied to the transmitter and receiver through W-band waveguide low loss transition structure design and impedance matching to verify the performance after the fabrication is 9.17 dB, which is close to the analysis result. As a result, it is judged that the transceiver can be applied to the small radar sensor better than the MMIC chip purchased overseas.

• Analytical Science and Technology
• /
• v.15 no.5
• /
• pp.417-426
• /
• 2002

Inductively Coupled Plasma Dynamic Reaction Cell Quadrupole Mass Spectrometry (ICP-DRC-QMS) was characterized for the detection of the six naturally occurring calcium isotopes. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. This experiment shows that the potentially interfering ions such as $Ar^+$, ${CO_2}^+$, ${NO_2}^+$, $CNO^+$ at the calcium masses m/z 40, 42, 43, 44 and 48 were removed by flowing $NH_3$ gas at the rate of 0.7 mL/min $NH_3$ as reactive cell gas in the DRC with a RPq value (rejection parameter) of 0.6. The limits of detection for $^{40}Ca$, $^{42}Ca$, $^{43}Ca$, $^{44}Ca$, and $^{48}Ca$ were 1, 29, 169, 34, and 15 pg/mL, respectively. This method was applied to the determination of calcium in synthetic food digest samples (CCQM-P13) provided by LGC for international comparison. The isotope dilution method was used for the determination of calcium in the samples. The uncertainty evaluation was performed according to the ISO/GUM and EURACHEM guidelines. The determined mean concentration and its expanded uncertainty of calcium was ($66.4{\pm}1.2$) mg/kg. In order to assess our method, two reference samples, Riverine Water reference sample (NRCC SLRS-3) and Trace Elements in Water reference sample (NIST SRM 1643d), were analyzed.

• Journal of KSNVE
• /
• v.8 no.5
• /
• pp.964-973
• /
• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• Journal of the Institute of Convergence Signal Processing
• /
• v.9 no.2
• /
• pp.104-111
• /
• 2008

The ECG is biomedical electrical signal occurring on the surface of the body due to the contraction and relaxation of the heart. This signal represents an extremely important measure for health monitoring, as it provides vital information about a patient's cardiac condition and general health. ECG signals are contaminated with high frequency noise such as power line interference, muscle artifact and low frequency nose such as motion artifact. But it is difficult to filter nose from ECG signal, and errors resulting from filtering can distort a ECG signal. The present study implemented a small-size and low-power ECG measurement system that can remove motion artifact for convenient health monitoring during daily life. The implemented ECG monitoring system consists of ECG amplifier, a low power microprocessor, bluetooth module and monitoring program. Amplifier was designed and implemented using low power instrumentation amplifier, and microprocessor was interfaced to the ECG amplifier to collect the data, process, store and feed to a transmitter. And bluetooth module used to wirelessly transmit and receive the vital sign data from the microprocessor to an PC at the receiving site. In order to evaluate the performance of the implemented system, we assessed motion artifact rejection performance in each situation with artificially set condition using adaptive filter.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.42 no.6
• /
• pp.67-76
• /
• 2005

This paper proposes a compact-sized surface myoelectric sensor for the myoelectric hand prosthesis. To fit the surface myoelectric sensor in the socket for the myoelectric hand prosthesis, the sensor should be a compact size. The surface myoelectric sensor is. composed of a skin interface and a single processing circuit that are mounted on a single package. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper we propose two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, we select the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22 mm. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value circuit. We evaluate the proposed sensor from the output characteristics according to the IED and the shape of the reference electrode. From the experimental results we show the surface myoelectric sensor with the 18mm IED and the bar-shaped reference electrode is suitable for the myoelectric hand prosthesis.

• Economic and Environmental Geology
• /
• v.46 no.6
• /
• pp.485-494
• /
• 2013

$CO_2$ Monitoring, Mitigation and Verification (MMV) is the essential part in the Carbon Capture and Storage (CCS) project in order to assure the storage permanence economically and environmentally. In large-scale CCS projects in the world, the seismic time-lapse survey is a key technology for monitoring the behavior of injected $CO_2$. In this study, we developed a basic process procedure for 3-D seismic baseline data from the Aquistore project, Estevan, Canada. Major target formations of Aquistore CCS project are the Winnipeg and the Deadwood sandstone formations located between 1,800 and 1,900 ms in traveltime. The analysis of trace energy and similarity attributes of seismic data followed by spectral decomposition are carried out for the characterization of $CO_2$ injection zone. High trace energies are concentrated in the northern part of the survey area at 1,800 ms and in the southern part at 1,850 ms in traveltime. The sandstone dominant regions are well recognized with high reflectivity by the trace energy analysis. Similarity attributes show two structural discontinuities trending the NW-SE direction at the target depth. Spectral decomposition of 5, 20 and 40 Hz frequency contents discriminated the successive E-W depositional events at the center of the research area. Additional noise rejection and stratigraphic interpretation on the baseline data followed by applying appropriate imaging technique will be helpful to investigate the differences between baseline data and multi-vintage monitor data.