• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.11
• /
• pp.1235-1239
• /
• 2010

In this work, a wideband technique has been proposed that improves the IF bandwidth of mixers and a 24-GHz down-conversion mixer employing the proposed technique has been designed and fabricated based on 0.13-${\mu}m$ RFCMOS technology. The mixer showed the conversion gain of $2.7{\pm}1.5$ dB from DC to 5.25 GHz IF for a fixed LO frequency of 24 GHz. Measured P-1dB and LO-RF isolation was -8.7 dBm and 21 dB, respectively. The mixer draws DC current of 10.6 mA from 1.3 V supply.

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.8
• /
• pp.42-47
• /
• 1999

In this paper, a mixture interacting multiple model (MIMM) algorithm is proposed to enhance speech contaminated by additive nonstationary noise. In this approach, a mixture hidden filter model (HFM) is used to model the clean speech and the noise process is modeled by a single hidden filter. The MIMM algorithm, however. needs large computation time because it is a recursive method based on multiple Kalman filters with mixture HFM. Thereby, a computationally efficient implementation of the algorithm is developed by exploiting the structure of the Kalman filtering equation. The simulation results show that the proposed method offers performance gain compared to the previous results in [4,5] with slightly increased complexity.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.4
• /
• pp.54-59
• /
• 2003

In this paper, a cylindrical dielectric antenna with dielectric clad is designed and analyzed. Design parameters of a cylindrical dielectric resonator antenna are calculated from the wave equation of cylindrical dielectric. The variations of characteristics of the antenna are analyzed as varying the thickness and the relative permittivity of its clad. From the results, when the ratio of the outside radius of the dielectric clad to the radius of the cylindrical dielectric is 1.3 and the relative permittivity of the dielectric clad is one-third of the cylindrical dielectric resonator antenna, the relative bandwidth of the antenna is 49%, which is improved by 2.3 times than the cylindrical dielectric resonator antennas. However, the thickness and the relative permittivity of the dielectric clad have not effect on the radiation pattern, beamwidth and gain of the antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.4
• /
• pp.427-432
• /
• 2010

To reduce the outage probability and to increase the transmission capacity, the importance of repeaters in cellular systems is increasing. But a RF(Radio Frequency) repeater has a problem that the output of the transmit antenna is partially feedback to the receive antenna, which is feedback interference. In this paper, we proposed adaptive Sign-Sign LMS(Least Mean Square) algorithm using correlations for the performance enhancement of RF repeater. The weight vector is updated by using sign of input signal and error signal to the least squared error of the conventional algorithms. When compared with the conventional method, the proposed canceller achieves the maximum 10 dB performance gain in terms of the MSE(Mean Square Error).

• Proceedings of the Korea Contents Association Conference
• /
• 2004.05a
• /
• pp.423-428
• /
• 2004

In this paper, STBC (Space Time Block Code) is applied to the WB system and frequency repeated diversity is used to get the 4-th order space time diversity gain. The performance of が STDB-OFDM system is analyzed by computer simulation. As a result of simulation, proposed W system can reduce the complexity that is introduced by increasing number of transmit antenna and show the same performance of 4 antennas with only using 2. Proposed system shows the enhancement of 7.1 dB compared to the general UWB OFDM and 1.9 dB compared to UWB STBC-OFDM.

• Nutrition Research and Practice
• /
• v.1 no.3
• /
• pp.175-179
• /
• 2007

The present study was performed to elucidate the hypocholesterolemic action of chitosan on the diet-induced hypercholesterolemia in rats. Male Sprague-Dawley rats (n=24) were fed with chitosan-free diet (Control), diets containing 2% or 5% chitosan for 4 weeks. Hypercholesterolemia was induced by adding 1% cholesterol and 0.5% cholic acid to all diets. Body weight gain and food intake of rats did not differ among the groups. The chitosan treated groups showed significant improvement in the plasma concentration of total cholesterol and LDL-cholesterol compared to the control group (p<0.05). Also, the chitosan treated groups decreased the liver concentration of total lipid and total cholesterol compared to the control group (p<0.05). The activity of hepatic cholesterol $7{\alpha}-hydroxylase$ (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids, was increased by 123% and 165% for the 2% or 5% chitosan diets, respectively. These findings suggest that enhancement of hepatic CYP7A1 activity may be a mechanism, which can partially account for the hypocholesterolemic effect of dietary chitosan in cholesterol metabolism.

• Proceedings of the Korea Institute of Convergence Signal Processing
• /
• 2006.06a
• /
• pp.53-56
• /
• 2006

In this paper, we present the algorithm to enhance the high frequency components of the image by subtracting smoothing version of an image from the original image. In a word, this is the technique to get more a precise and vivid image. The method of Gaussian smoothing is accepted to get the components of the flat image. Moreover we need to consider the size of the gain of the proposed filter in order to preserve the overall brightness of a image. Based on the algorithm verified by MATLAB, we can obtain more vivid and fuller detail of the image than an original image.

• Journal of the Korea Society of Computer and Information
• /
• v.4 no.4
• /
• pp.185-192
• /
• 1999

In this paper. for $\pi$/4 and $\pi$/8 PSK. we proposed to condition to obtain coding gain increasing states, by design encoder of analytical method with minimal complexity in limited bandwidth and power channels. In order to improve the bit error rate(BER), comparing Ungerboeck designed the TCM. we propose MTCM(Multiple trellis-coded modulation) with multiplicity(k＝2), by optimum encoder design. By design encoder of analytical method. the trellis encoder can be minimal complexity and the decoder be used Viterbi decoder(MLSE). When compared to the TCM and MTCM with AWGN channels. the condition of performance enhancement of the MTCM with multiplicity(k＝2) is the case of parallel transition in TCM systems. without alternating data transmission rate in bandwidth and power limited channels.

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.620-625
• /
• 2014

The effect of polyvinyl alcohol/polyamide-epichlorohydrin (PVA/PAE) complex strengthening additive on dry and wet strength and surface properties of paper was investigated. The enhancements of dry and wet strength and dimensional stability were found when PVA/PAE was applied as a complex strengthening additive compared with the cases of applying individual PVA or PAE. This was understood as physical crosslinking between PVA and PAE in the PVA/PAE complex strength additive. This complex strengthening additive also lowered surface roughness and increased sizing. As a result, PVA/PAE complex strengthening additive provided the distinctive gain dot in printed papers.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.4
• /
• pp.443-450
• /
• 2016

The linearization technique for low noise amplifier (LNA) has been implemented in standard $0.18-{\mu}m$ BiCMOS process. The MOS-BJT derivative superposition (MBDS) technique exploits a parallel LC tank in the emitter of bipolar transistor to reduce the second-order non-linear coefficient ($g_{m2}$) which limits the enhancement of linearity performance. Two feedback capacitances are used in parallel with the base-collector and gate-drain capacitances to adjust the phase of third-order non-linear coefficients of bipolar and MOS transistors to improve the linearity characteristics. The MBDS technique is also employed cascode configuration to further reduce the second-order nonlinear coefficient. The proposed LNA exhibits gain of 9.3 dB and noise figure (NF) of 2.3 dB at 2 GHz. The excellent IIP3 of 20 dBm and low-power power consumption of 5.14 mW at the power supply of 1 V are achieved. The input return loss ($S_{11}$) and output return loss ($S_{22}$) are kept below - 10 dB and -15 dB, respectively. The reverse isolation ($S_{12}$) is better than -50 dB.