• Journal of Sensor Science and Technology
• /
• v.24 no.3
• /
• pp.194-201
• /
• 2015

The current sensor is used in industrial devices and power utilities. Core materials of these current sensors are divided into mainly two groups as silicon steel and fermalloy. Silicon steel has a wide saturation bandwidth but low sensitivity during low-current, whereas permalloy has a short saturation bandwidth but high sensitivity during low-current. In this paper, laminated silicon steel and permalloy by equal ratio is proposed to improve the linearity and saturation of current sensor. It is proved that the proposed core material has larger bandwidth than fermalloy as well as higher sensitivity than silicon steel. When comparing simulation results by FLUX 3D, the proposed method has also better performance than the previous core materials.

• ETRI Journal
• /
• v.28 no.2
• /
• pp.175-181
• /
• 2006

A new CMOS voltage-controlled fully-differential transconductor is presented. The basic structure of the proposed transconductor is based on a four-MOS transistor cell operating in the triode or saturation region. It achieves a high linearity range of ${\pm}\;1\;V$ at a 1.5 V supply voltage. The proposed transconductor is used to realize a new fully-differential Gm-C low-pass filter with a minimum number of transconductors and grounded capacitors. PSpice simulation results for the transconductor circuit and its filter application indicating the linearity range and verifying the analytical results using $0.35\;{\mu}m$ technology are also given.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.211-212
• /
• 2006

This paper represents a Doherty amplifier with analog predistorter to improve the linearity of the Doherty amplifier while preserving the high efficiency. A $3^{rd}$-order predistorter cancels $5^{th}$-order intermodulation (IM5) as well as $3^{rd}$-order intermodulation (IM3) components by their same phase difference in the predistorter and Doherty amplifier. This is accomplished by independently controlling their phase by using the phase-controlled error generator in the predistorter. For experimental verification, a $3^{rd}$-order predistorter has been implemented and tested in a 180-W Doherty amplifier at the wide-band code division multiple access (WCDMA) band. The measured results show good performance with the predistortion Doherty amplifier.

• 한국정보통신설비학회:학술대회논문집
• /
• 2005.08a
• /
• pp.149-153
• /
• 2005

The optical fiber micro-cellular system requires the high linearity that determines the quality and capacity of system. Hence, there is a need for improving the linearity in mobile communication system. In order to compensate dispersion-induced signal distortion, we fabricated the optical feedforward transmitter. The compared 3rd-IMD was enhanced by 38 dB for two-tone case and the Adjacent Channel Power Ratio was enhanced by 20 dB for W-CDMA 1 carrier and by 16 dB for W-CDMA 3 carriers. Also, the induced noise level was reduced.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.11
• /
• pp.1934-1939
• /
• 2006

Current digital communication system is selecting very various digital Modulation way. Need linear power amplifier necessarily to reduce interference for contiguity channel maximum in this communication system and at the same time, power amplifier of high efficiency is required. In this paper Compare with result of equilibrium power amplifier that design Doherty power amplifier of way that linearity and efficiency are improved at the same time through simulation optimization techniques and at the same time design through simulation, efficiency 20% linearity showed 10dB that is improved.

• Journal of the Korea Computer Industry Society
• /
• v.6 no.3
• /
• pp.429-436
• /
• 2005

The linear modulation method which has high spectrum efficiency when applying in mobile communication system, the problem occurs. In order to solve like this problem non-linearity characteristic of the power amplifier linearity against the method which it does it investigated. It used a design objection and it implemented the microwave power amplifier. The amplifier which it produces used the micro-strip line and when it imput power 13 dBm from center frequency, the possibility of getting the output power of 28 dBm.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.9
• /
• pp.60-67
• /
• 2007

A signal conditioning circuit for capacitive displacement sensors was developed using a high frequency modulation/demodulation method, and its performance was evaluated. Since capacitive displacement sensors can achieve high resolution and linearity, they have been widely used as precision sensors within the range of several hundred micrometers. However, they inherently have a limitation in low frequency range and some nonlinearity characteristics and so a specially designed signal conditioning circuit is needed to handle these properties. The developed signal processing circuit consists of three parts: linearization, modulation/demodulation, and nonlinearity compensation. Each part was constructed discretely using several IC chips and passive elements. An evaluation system for precision displacement sensors was developed using a laser interferometer, a precision stage, and a PID position controller. The signal processing circuit was tested using the evaluation system in the respect of resolution, repeatability, linearity, and so on. From the experimental results, we know that a highly linear voltage output can be obtained successfully, which is proportional to displacement and the nonlinearity of output is less than 0.02% of full range. However, in the future, further investigation is required to reduce noise level and phase delay due to a low-pass filter. The evaluation system also can be applied effectively to calibration and evaluation of precision sensors and stages.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7A
• /
• pp.738-745
• /
• 2007

The non-linearity of HPA(high power amplifier) which is an important component in modern communications systems introduces AM/AM and AM/PM distortion so that the transmitted signal is deteriorated. And, the I/Q unbalances and phase error which are generated by non-ideal components are inevitable physical phenomena and lead to performance degradation when we implement a practical two-dimensional (2-D) modulation system. In this paper, we provide an exact and general expression involving the 2-D Gaussian Q-function for the error probabilities of arbitrary 2-D signaling with I/Q amplitude and phase unbalances in nonlinear additive white Gaussian noise (AWGN) channels by using the coordinate rotation and shifting technique.

• Analytical Science and Technology
• /
• v.30 no.3
• /
• pp.154-158
• /
• 2017

The Korean Pharmacopoeia (KP XI), British Pharmacopoeia (BP 2013) and Japanese Pharmacopoeia contain monographs for the quality control of raw fusidate sodium and its formulations using high performance liquid chromatography (HPLC). However, the assay method for the determination of fusidate sodium in commercial tablets is titration which is less specific than HPLC. In this study, we present an alternative HPLC method for quantitation of fusidate sodium in tablets. Method validation was performed to determine linearity, precision, accuracy, system suitability, and robustness. The linearity of calibration curves in the desired concentration range was high ($r^2=0.9999$), while the RSDs for intra- and inter-day precision were 0.25-0.37 % and 0.11-0.60 %, respectively. Accuracies ranged from 99.46-100.85 %. Since the system suitability, intermediate-precision and robustness of the assay were satisfactory, this method will be a valuable addition to the Korean Pharmacopoeia (KP XI).

• Korean Journal of Pharmacognosy
• /
• v.40 no.3
• /
• pp.224-228
• /
• 2009

For the quality control of traditional herbal medicine, Galgeun tang, simultaneous determination of glycyrrhizin, paeoniflorin, puerarin, 6-gingerol was established by using a high performance liquid chromatographic (HPLC) method with diode array detector. To separate five four constituents, DIONEX $C_{18}$ column ($5{\mu}m$, $120{\AA}$, $4.6\;mm{\times}150\;mm$) was used with gradient elution system of water and methanol. Validation of the chromatography method was evaluated by linearity, recovery, and precision test. Calibration curve of standard components showed excellent linearity ($R^2$>0.9906). Limits of detection (LOD) and limits of quantification (LOQ) varied from 0.15 to $0.52{\mu}g$/ml and 0.27 to $0.80{\mu}mg$/ml, respectively. The relative standard deviations (RSDs) of data of the intra-day and inter-day experiments were less than 2.88% and 1.21%, respectively. The results of recovery test were ranged from 96.71 to 106.29% with RSD values 0.01-0.80%.