• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.55-64
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• 2006

This work proposes a calibration-free 14b 70MS/s 0.13um CMOS ADC for high-performance integrated systems such as WLAN and high-definition video systems simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs signal insensitive 3-D fully symmetric layout techniques in two MDACs for high matching accuracy without any calibration. A three-stage pipeline architecture minimizes power consumption and chip area at the target resolution and sampling rate. The input SHA with a controlled trans-conductance ratio of two amplifier stages simultaneously achieves high gain and high phase margin with gate-bootstrapped sampling switches for 14b input accuracy at the Nyquist frequency. A back-end sub-ranging flash ADC with open-loop offset cancellation and interpolation achieves 6b accuracy at 70MS/s. Low-noise current and voltage references are employed on chip with optional off-chip reference voltages. The prototype ADC implemented in a 0.13um CMOS is based on a 0.35um minimum channel length for 2.5V applications. The measured DNL and INL are within 0.65LSB and l.80LSB, respectively. The prototype ADC shows maximum SNDR and SFDR of 66dB and 81dB and a power consumption of 235mW at 70MS/s. The active die area is $3.3mm^2$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1250-1259
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• 2012

In this paper, a time-domain comparator is proposed for a successive approximation (SA) analog-to-digital converter (ADC) with a low power and high resolution. The proposed time-domain comparator consists of a voltage-controlled delay converter with a clock feed-through compensation circuit, a time amplifier, and binary phase detector. It has a small input capacitance and compensates the clock feed-through noise. To analyze the performance of the proposed time-domain comparator, two 1V 10-bit 200-kS/s SA ADCs with a different time-domain comparator are implemented by using 0.18-${\mu}m$ 1-poly 6-metal CMOS process. The measured SNDR of the implemented SA ADC is 56.27 dB for the analog input signal of 11.1 kHz, and the clock feed-through compensation circuit and time amplifier of the proposed time-domain comparator enhance the SNDR of about 6 dB. The power consumption and area of the implemented SA ADC are 10.39 ${\mu}W$ and 0.126 mm2, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.471-482
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• 2015

In this paper, design and implementation of the 94 GHz Gunn oscillator and the evaluation of the maximum power of the Gunn diode used in the oscillator are presented. The 94 GHz Gunn oscillator is used InP Gunn diode and designed employing a WR-10 waveguide. The designed oscillator is fabricated through machining and its performance is measured. The fabricated oscillator shows an oscillation frequency of 95 GHz, output power of 12.64 dBm, and phase noise of -92.7 dBc/Hz at 1 MHz offset frequency. To evaluation the maximum power of the InP Gunn diode used in oscillator, the oscillator structure is modified to a structure having a diaphram. The height of thick diaphram which is used in the oscillator is varied. As a result, an oscillator has several different load impedances, which makes it possible to plot $G_L-V^2$ plot at the post plane. Using the $G_L-V^2$ plot, the maximum power of used Gunn diode including post is computed to be 16.8 dBm. Furthermore using the shorted and zero bias Gunn diode, the post loss used for DC biasing can be computed. Using the two losses, The maximum power of a InP Gunn diode is computed to be 18.55 dBm at 95 GHz. This result is close to a datasheet.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1603-1615
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• 2018

In order to achieve the low complexity and area, power in the design of Optical Image Stabilization (OIS) suitable for the smart phone, this paper presents the following design explorations, such as; optimization of gyroscope sampling rate, simple and accurate gyroscope filters, and reduced operating frequency of motion compensation, optimized bit width in ADC and DAC, evaluation of noise effects due to PWM driving. In experiments of gyroscope sampling frequencies, it is found that error values are unvaried in the frequency above 5KHz. The gyroscope filter is efficiently designed by combining the Fuzzy algorithm, to illustrate the reasonable compensation for the angle and phase errors. Further, in the PWM design, the power consumption of 2MHz driving is shown to decrease up to 50% with respect to the linear driving, and the imaging noises are reduced in the driving frequency above 2MHz driving frequency. The operating frequency could be reduced to 5KHz in controller and 10KHz in driver, respectively, in the motion compensation. For ADC and DAC, the optimized exploration experiments verify the minimum bit width of 11bits in ADC as well as 10bits in DAC without the performance degradation.

• Analytical Science and Technology
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• v.18 no.3
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• pp.250-256
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• 2005

A selective method of high performance liquid chromatography with UV detector has been applied to determine 4 tetracycline antibiotics in the animal food, simultaneously. The targets were chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC), and tetracycline (TC) that are used routinely in veterinary medicine for prevention and control of disease. Food samples were beef, pork, chicken, milk, whole egg, flatfish (Limanda yokohamae), jacopever (Sebastes hubbsi), seabream (Chrysophrys major), eel (Anguilla japonica) and lobster (Hommarus americanus). After extracting food samples with 20% trichloroacetic acid and McIlvaine buffer, they were purified by a $C_18$ SPE cartridge with 0.01M methanolic oxalic acid solution. The concentrated residue was re-dissolved in methanol, filtered, cleaned up and analyzed on a $C_18$ column. The mobile phase was a mixture of 0.01M oxalic acid and acetonitrile with a gradient ratio from 85:15 to 60:40. The UV wavelength was 365 nm. The overall recoveries were ranged from 71% to 98% and the limit of detections were 0.022 for CTC, 0.012 for DC and OTC and 0.009 mg/kg for TC at signal/noise > 3, respectively. As results, CTC, DC and TC were not detected in all selected food samples, however, OTC was detected in meat and fishes. The determined level of OTC was 0.04 ppm for pork, 0.17 ppm for flatfish and 0.05 and 0.08 ppm for jacopever, that were within the Maximum Residue Limits (MRLs) in the food.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1797-1806
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• 1998

Future satellite communication systems will be developed at Ka-band (20/30 GHz) owing to the relatively wide frequency allocation and current freedom from terrestrial interference for multimedia services. A serious disadvantage of the Ka-band, however, is the very high atmospheric attenuation in rainy weather. Synchronous CDMA drastically redces the effect of self-noise with several interesting features of CDMA for mobile communications such as fixible freuqncy rese, the capability of performin soft-handover and a lower sensitivity to interference. This paper evaluates the performance of a synchronous CDMA reture link for a Ka-band geostationary satellite communication system. For a fixed satellite channel whose characteristics depend on weather conditions, the signal envelope and phase for this channel is modelled as Gaussian. The bit error and outage probability, and the detection loss due to imperfect chip timing synchronization is analytically evaluated and the system capacity degaradation due to the weather condition is estimated. The two cases consist of the general case in which all users are affected by rain condition, and the worst case in which the reference user is only affected by rain attenuation. the results for two cases of rain condition clearly show that synchronous CDMA eases the power control requirements and has less sensitivity to imperfect power control.

• Journal of the Korean Magnetics Society
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• v.25 no.6
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• pp.189-197
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• 2015

As enforced the regulation of fuel efficiency, the electrification of automotive components in internal combustion vehicle has been applied instead of hydraulic pressure. A typical example of such parts is the EPS (electric power steering), and it is applied to most automotive at present. In electric power steering system, the core component is motor. The reduction of cogging torque and torque ripple is required to improve steering feeling and reduce NVH (Noise Vibration Harshness) in EPS. Generally the skewed design of stator or rotor is applied in order to reduce cogging torque and torque ripple. This paper propose the design and analysis methodology of Brusheless PMSM (Permanent Magnet Synchronous Motor) which is applied to skewed stator. The proposed methodology is as follows: First Intial Design PMSM with skewed stator for EPS, Second Optimal design using RSM (Response surface method), Third Performance Analysis such as Phase Back EMF, Inductance, Load torque using FEA (Finite Element Method). Finally, the reliability of proposed design methodology will be verified through the experiments of prototype sample.

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.79-84
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• 2012

Nano-magnetic materials such as iron-nitrides have been actively studied as an alternative to the application of high density, high performance needs for next generation information storage and also alternative to the rare earth and neodymium magnet. $Fe_4N$ is the basic materials for magnetic storage media and is one of the important magnetic materials in focus because of its higher magnetic recording density and chemical stability. Single phase ${\gamma}^{\prime}-Fe_4N$ nanoparticles have been prepared by a PAD (Plasma Arc Discharge) method and nitriding in a $NH_3-H_2$ mixed gases at temperature, $400^{\circ}C$ for 4 hrs. Also $Fe_{17}Sm_2N_x$ powders were synthesized by nitriding after reduction/diffusion of $Fe_{17}Sm_2$ to compare the magnetic properties with nano-sized $Fe_4N$ particles. The saturation magnetization of $Fe_4N$ and $Fe_{17}Sm_2N_x$ were 149 and 117 emu/g, respectively, but the coercive force was considerably smaller than that of bulk or acicular $Fe_4N$.

• Analytical Science and Technology
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• v.17 no.6
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• pp.520-526
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• 2004

To determine 6 anti-impotence drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil and hongdenafil in food, simultaneously, high performance liquid chromatography was applied. In the case of solid sample, it was extracted in organic solvents after homogenizing with mortar and pestle. Whereas liquid sample was just diluted in water and then extracted in organic solvents. Maximum lengths of UV for targets have been identified on photodiode array spectra. As results, vardenafil, hongdenafil, hydroxyhomosildenafil, sildenafil, homosildenafil, and tadalafil were eluted in order using $C_{18}$ column in acetonitrile containing phosphoric acid as the mobile phase. The maximum wavelength (${\lambda}_{max}$) was 216 nm for vardenafil, 233 and 282 nm for hongdenafil, 222 and 293 nm for hydroxyhomosildenafil, sildenafil and homosildenafil, and 284 nm for tadalafil. The overall recoveries were ranged from 95% to 109% and the limit of detection was about 0.04 mg/kg at signal/noise>3. Levels of targets in the selected food samples were 1.7 (hongdenafil) ~ 63 (tadalafil) mg/one dose.

• Journal of Navigation and Port Research
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• v.43 no.3
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• pp.172-178
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• 2019

Although the needs for providing resilient PNT information are increasing, threats due to the intentional RFI or space weather change are challenging to resolve. eLoran, which is a terrestrial navigation system that use a high-power signal is considered as a best back-up navigation system. Depending on the user's environment in the eLoran system, the user may use one of E-field or H-field antennas. H-field antenna, which has no restriction on setting stable ground and is relatively resistant to noise of general electronic equipment, is composed of two loops, and shows anisotropic gain pattern due to the different measurement at the two loops. Therefore, the H-field antenna's phase estimation value of signal varies depending on its direction even at the static environment. The error due to the direction of the signal should be eliminated if the user want to estimate the own position more precisely. In this paper, a method to compensate the error according to the geometric distribution between the H-field antenna and the transmitting station is proposed. A model was developed to compensate the directional error of H-field antenna based on the signal generated from the eLoran signal simulator. The model is then used to the survey measurement performed in the land area and verify its performance.