• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.547-552
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• 1989

Single mode optical fiber interferometeric sensors using phase tracking homodyne detection are typically susceptible to environmentally induced temperature fluctuations and other types of disturbances. In this paper compensator is described, which is a simple and effective phase tracking feedback electronic circuit must be output signal stabilized to achieve maximln sensitivity and linearity of Mach-Zehnder fiber-optic interferomter in the presence of differential phase drift. The phase tracking range of the piezoelectric cylinder in the reference arm is .+-.3.7.pi.rad, and the probe mass about 1 gram in the sensing ann was used for measurements of the gravity acceleration.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.5
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• pp.152-161
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• 1989

Conventional design methods for CTD (charge transfer devices) FIR filters, whose coefficients consist of +1, 0, and -1, do not guarantee the phase linearity of the resulting filter, To obtain the linear phase filter, in this paper, an improved algorithm is presented based on the symmetry property of the linear phase filter coefficients. It has been shown that the proposed algorithm results in the linear phase filter and that the computational complexity of the proposed algorithm is reduced by an half of that in the existing method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.2032-2038
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• 1989

Single mode optical fiber interferometeric sensors using phase tracking homodyne detection are typically susceptible to environmentally indured temperature fluctuations and other types of disturbances. A simple and effective phase tracking feedback electronic circuit for compensator is described to achieve stabilizing signal output, maximum sensitivity and linearity in the fiber optic Mach-Zehnder infterferometer in the presence of differential phase drift. The phase tracking range of the piezoelectric cyclinder in the reference arm is \ulcorner.7 \ulcornerad and the prabe mass about 1 gram in the sensing arm was used for measurements of the gravity acceleration.

• Proceedings of the KIEE Conference
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• summer
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• pp.1025-1027
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• 2004

Recently, the Single phase SRM has been researched and developed in many appliances with various types. This paper presents a theoretical representation of the phase inductance of a single phase SRM, as function of position and current, taking into account the non-linearity of the magnetic circuit. The method is based on the Fourier series expansion. the theoretical expressions for the calculation of instantaneous phase inductance, flux linkage, coenergy and electromagnetic torque as a function of rotor position and winding currents are derived. And it is compared with the results of the finite element analysis.

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.1-5
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• 2016

In this paper, High Power Pulsed Amplifier with wide-band characteristic is implemented for L-band Navigational Aid(NAVAID). Due to the characteristics of L-Band NAVAID, implemented SSPA is demanded characteristics of high RF power, high linearity and high efficiency. Therefore, in this paper, efficiency characteristic is improved by modified class F technique. And linearity characteristic is improved by balance structure using hybrid coupler, $2^{nd}$ & $3^{rd}$ harmonic trap and anti-phase technique using non-linear characteristics of drive amplifier. Implemented SSPA shows that bandwidth of 300MHz, RF Output power of 1.5KW and efficiency of 55%.

• Analytical Science and Technology
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• v.36 no.6
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• pp.281-290
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• 2023

Zidovudine is an antiretroviral agent prescribed for the prevention and treatment of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). It is typically recommended to be used in combination with other antiretroviral drugs. Zidovudine has the potential to generate N-nitrosodimethylamine (NDMA) in the presence of dimethylamine and nitrite salt under acidic reaction conditions during the drug manufacturing process. NDMA is a potent human carcinogen that may be detected in drug substances or drug products. An analytical method was developed to determine NDMA in pharmaceuticals including zidovudine using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The analysis involved reversed-phase chromatography on a Kinetex F5 column with a mobile phase comprising water-acetonitrile mixtures. The detection of positively charged ions was conducted using atmospheric pressure chemical ionization (APCI). The calibration curve demonstrated excellent linearity (r = 0.9997) across the range of 1-50 ng/mL with a highly sensitive limit of detection (LOD) at 0.3 ng/mL. The developed method underwent thorough validation for specificity, linearity, accuracy, precision, robustness, and system suitability. This sensitive and specific analytical method was applied for detecting NDMA in zidovudine drug substance and its formulation currently available in the market, indicating its suitability for drug quality management purposes.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.229-235
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• 2014

This paper presents the Doherty power amplifier with a digitally controlled analog predistorter circuit of Scintera Corp. to produce high power efficiency and high linearity performance. The analog predistorter improves the linearity performance because of controlling amplitude and phase values of input signal in order to improve intermodulation performance of power amplifier. Also, the power amplifier is designed by the Doherty technology to obtain the high efficiency performance. To validate the Scintera's analog predistorter, we are implemented the power amplifier with Doherty method at center frequency 2150 MHz. Compared with the balanced amplifier, the power amplifier is improved above 11% enhanced efficiency and more than 15 dB ACPR improvement.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.450-455
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• 1995

A three-dimensional numerical tool is developed to calculate the potential distribution, electric field, and conductance for any types of conductance probes immersed in the wavy liquid film with various shapes of its free surface. The tool is validated against various analytical solutions. It is applied to find out the characteristics of the wire-wire probe, the flush-wire probe and the flush-flush probe in terms of resolution, linearity, and sensitivity. The wire-wire probe shows high resolution and excellent linearity for various film thickness, but comparably low sensitivity for low film thickness fixed. The flush-wire probe shows good linearity and high sensitivity for varying film thickness, but resolution degrading with an increase in film thickness. In order to check the applicability of the three types of probes in the real situation, the Korteweg-de Vries(KdV) two-dimensional solitary wave is simulated. The wire-wire probe is strongly affected by the installation direction of the two wires; when the wires are installed perpendicularly to the flow direction, the wire-wire probe shows large distortion of the solitary wave. In order to measure the transverse profile of waves, the wire-wire probes and the flush-wire probes are required to be separately installed 2mm and 2mm, respectively.

• Journal of electromagnetic engineering and science
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• v.7 no.2
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• pp.91-95
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• 2007

In this paper, a new linearization method has been proposed for a CMOS low noise amplifier(LNA) using the Post IM3 Compensator. The fundamental operating theory of the proposed method is to cancel the IM3 components of the LNA output signal by generating another IM3 components, which are out-phase with respect to that of the LNA, from the Post IM3 Compensator. A single stage common-source LNA has been designed to verify the linearity improvement of the proposed method through $0.13{\mu}m$ RF CMOS process for WiBro system. The designed LNA achieves +7.8 dBm of input-referred 3^{rd}$-order intercept point (IIP3) with 13.2 dB of Power Gain, 1.3 dB of noise figure and 5.7mA @1.5V power consumption. IIP3 is compared with a conventional single stage common-source LNA, and it shows IIP3 is increased by +12.5 dB without degrading other features such as gain and noise figure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.433-437
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• 2015

We have designed and fabricated a low power and high linearity up down convertor for wireless repeaters using $0.35{\mu}m$ SiGe Bipolar CMOS technology. Repeater is composed of a wideband up/down converting mixer, programmable gain amplifiers (PGA), input buffer, LO buffer, filter driver amplifier and integer-N phase locked loop (PLL). As of the measurement results, OIP3 of the down conversion mixer and up conversion mixer are 32 dBm and 17.8 dBm, respectively. The total dynamic gain range is 31 dB with 1 dB gain step resolution. The adjacent channel leakage ratio (ACLR) is 59.9 dBc. The total power consumption is 240 mA at 3.3 V.