• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.668-676
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• 2018

In satellite communications, a modulation technique with a low peak-to-average power ratio, high transmission efficiency, and low bit error rate(BER) is required, and differential amplitude and phase shift keying(DAPSK) modulation technique has been appraised as a technology that meets these requirements. However, because conventional DAPSK modulation uses a regular constellation diagram, the Euclidean distance between the symbols in the inner concentric circles of the constellation are quite short. Such a characteristic degrades the BER. In this paper, we propose a DAPSK system that uses an efficient constellation assignment to improve the performance of existing DAPSK systems and evaluate the performance of the proposed scheme. From the simulation results, we confirm that the proposed 16-DAPSK system achieves an signal-to-noise ratio gain of 0.8 dB over the conventional approach at a BER condition of $10^{-4}$ when the number of symbols used in the symbol detector of the receiver is 2.

• Journal of Broadcast Engineering
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• v.20 no.3
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• pp.398-407
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• 2015

Compressive sensing (CS) has drawn much interest as a novel sampling technique that enables sparse signal to be sampled under the Nyquitst/Shannon rate. By noting that the block-based CS can still keep spatial correlation in measurement domain, this paper proposes to adapt sampling rate of each block in frame according to its characteristic defined by edge information. Specifically, those blocks containing more edges are assigned more measurements utilizing block-wise correlation in measurement domain without knowledge about full sampling frame. For natural image, the proposed adaptive rate allocation shows considerable improvement compared with fixed subrate block-based CS in both terms of objective (up to 3.29 dB gain) and subjective qualities.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.647-650
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• 2013

HEVC RExt(High Efficiency Video Coding Range Extension) set a goal to support RGB/YUV 4:2:2 4:4:4 color sampling and over 10 bit-depth images. Unlike the previous 4:2:0 color sampling images, RGB images have the high correlation in inter-color planes. Using this characteristic, some methods which are contributed in JCT-VC standardization meetings estimate the pixel values of inter-color plane. But when we use the estimation of inter-color plane in RGB images, high frequency components of RGB images are caused to reduce the coding efficiency because they usually have the low inter-color plane correlation. Therefore, in this paper, we propose an adaptive low pass filtering method in the inter-color plane estimation. Using this method, we can improve the estimation efficiency of inter-color plane in RGB images. The experimental results with HEVC RExt RGB test sequences show that the proposed method has 0.6% BD(Bjontegaard Distortion)-rate gain and some increased complexity compared to the previous inter-color plane estimation method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.1-8
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• 2005

In this paper, design and implement 60W Doherty power amplifiers for 3GPP repeater and base station transceiver system. Efficiency improvement and high power property of Doherty power amplifier is distinguishable; however implementation of assistance amplifer is difficult, though. To solve the problem, therefore, GCHD (Gate Control Hybrid Doherty) power amplifier is embodied to gate bias adjusament circuit of assistance amplifier to General Doherty power amplifier. Experiment result shows that $2.11\~2.17GHz$, 3GPP operating frequency band, with 62.55 dB gain, PEP output is 50,76 dBm, W-CDMA average power is 47.81 dBm, and -40.05 dBc ACLR characteristic in 5MHz offset frequency band. Each of the parameter satisfied amplifier specification which we want to design. Especially, GCHD power amplifier shows proper efficiency performance improvement in uniformity ACLR than general power amplifier.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.301-306
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• 2015

An ultra-compact and wideband low noise amplifier (LNA) in a quad flat non-leaded (QFN) package is presented. The LNA monolithic microwave integrated circuit (MMIC) is implemented in a $0.25{\mu}m$ GaN IC technology on a Silicon Carbide (SiC) substrate provided by Triquint. A source degeneration inductor and a gate inductor are used to obtain the noise and input matching simultaneously. The resistive feedback and inductor peaking techniques are employed to achieve a wideband characteristic. The LNA chip is mounted in the $3{\times}3-mm^2$ QFN package and measured. The supply voltages for the first and second stages are 14 V and 7 V, respectively, and the total current is 70 mA. The highest gain is 13.5 dB around the mid-band, and -3 dB frequencies are observed at 0.7 and 12 GHz. Input and output return losses ($S_{11}$ and $S_{22}$) of less than -10 dB measure from 1 to 12 GHz; there is an absolute bandwidth of 11 GHz and a fractional bandwidth of 169%. Across the bandwidth, the noise figures (NFs) are between 3 and 5 dB, while the output-referred third-order intercept points (OIP3s) are between 26 and 28 dBm. The overall chip size with all bonding pads is $1.1{\times}0.9mm^2$. To the best of our knowledge, this LNA shows the best figure-of-merit (FoM) compared with other published GaN LNAs with the same gate length.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.922-929
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• 2007

In this paper, a rectangular loop array antenna for beam scanning is designed. A program using RWG MoM(Rao Wilton Glisson Method of Moment) is developed for SEP(Scan Element Pattern) theoretically. Simulation results obtained by using a commercial software tool, MWS are compared with the MoM results to confirm the validity of the program. Also these results are compared with the measured ones for the case of an $8{\times}5$ subarray. The fabricated $8{\times}5$ subarray showed a flat gain characteristic in the elevation scan range of ${\pm}45^{\circ}$ in the E-plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.286-297
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• 2017

This paper is a study of 6~18 GHz wideband high power amplifier which is composed of 10 single amplifier and coaxial type spatial power combiner. The property of this spatial power combiner is on a similar principle to antipodal antenna radiation mechanism. Therefore, the key structure of proposed spatial power combiner is the antipodal finline PCB board and the finline curve shape is numerically synthesized by using Klopfensein's optimum impedance taper. The measured CW output power of spatial combined high power amplifier is nearly 50 W. In conclusion we prove the good combining performance between the spatial power combiner and 10 single amplifier over 6~18 GHz frequency ranges. Also, we developed the key component PA and MFC MMIC which controls the phase and gain of the each amplifier, The main characteristic of MFC MMIC is to maximize combining efficiency of power amplifier.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.1
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• pp.80-88
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• 2016

Twenty crossbred steers ($400{\pm}40.1kg$ of initial body weight) were used to assess the effects of a dietary supplementation with crude glycerin (CG) as a substitute for corn grain on performance, carcass traits, and meat quality. Four isocaloric and isonitrogenous diets were offered to the experimental animals (5 steers per treatment) for 121 days using randomized complete block design. The steers individually received dietary treatments containing 0%, 7%, 14%, and 21% of CG (88.91% pure) on a dry matter (DM) basis. The diets were offered ad libitum as total mixed rations twice daily. Weight gain and carcass traits were determined. At the end of the experimental period, the harvest data and carcass characteristics of the steers were recorded, and meat quality was determined. No significant effect of CG inclusion was observed in any of the growth performance and carcass characteristics traits studied. Also, there were no apparent effects of diets (p>0.05) on meat quality (pH, water holding capacity, drip losses, and cooking losses). The study concluded that CG could be used as a substitute for corn grain up to the level of approximately 21% of DM in the diets of finishing steers.

• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.376-380
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• 2014

In the present study, oblique L-shaped monopole slot antenna with broadband characteristic is newly proposed. For bandwidth enhancement as well as size reduction, L-shaped slot with two open-terminations on the ground edge is used. The lower part of L-shaped slot comprises oblique form for bandwidth enhancement in low frequency band, whereas its higher part comprise tapered form for its enhancement in high frequency band. The short-circuit terminated microstrip line which is generally known to be more useful for bandwidth enhancement than open-circuit termination is used. The measured impedance bandwidth($S_{11}{\leq}-10dB$) and gain of the fabricated antenna have been observed to be 4.72 GHz (2.28~7 GHz) and more than 3dBi over the passband respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.5
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• pp.607-613
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• 2010

The influence of dietary supplementation with blended essential oil on growth performance, nutrient digestibility, blood profiles and fecal characteristics was evaluated in 125 crossed ((Duroc ${\times}$Yorkshire) ${\times}$Landrace) pigs (6.21${\pm}$0.20 kg initial body weight and 21 d average age). The pigs were allotted to the following treatments: i) NC (antibiotic free diet), ii) PC (NC diet+44 ppm tylosin), iii) T1 (NC diet+0.1% essential oil), iv) T2 (NC diet+0.1% essential oil (with 0.3% Benzoic acid)) and v) T3 (NC+22 ppm tylosin and 0.05% essential oil). Average daily gain (ADG) was improved in the T2 group on d 14 (p<0.05). In addition, nutrient digestibility was partially affected (both positively and negatively) by the treatments. Furthermore, the immune system was stimulated and the fecal pH and fecal noxious gases were improved in pigs that received the diets supplemented with essential oil (p<0.05). The appearance and score of diarrhea also tended to be lower in pigs that were subjected to the essential oil treatments. Collectively, the results of this study indicate that supplementation of the diet with blended essential oils could replace treatment with antibiotics to improve growth performance and fecal characteristics.