• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1313-1321
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• 2008

outphasing class-E power amplifier using composite right/left-handed transmission lines(CRLH-TL) is proposed at 2.4 GHz. The power combiner including CRLH-TL is designed to suppress the second and third harmonics to increase linearity and the output problem of the conventional outphasing amplifier is also solved by the proposed outphasing amplifier. So the P AE is improved. The measured maximum output power at the fundamental frequency shows 31.8 dBm, whereas the PAE shows 50 % with 14 dBm input power excited. The IMD3 is improved by 5 dB compared to that of conventional outphasing amplifier.

• Rubber Technology
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• v.9 no.1
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• pp.25-28
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• 2008

By combining the multi-faceted environmental responsiveness of polymer hydrogels with photonically active structures, there has been a significant effort to create color-tunable photonic crystal sensors by changing either the periodic spacing of the structure or the dielectric constants of the materials. Here, we show that reversible spiral and helical opal switches with both dimensional and optical functionalities that respond to environmental chemistry can be constructed. When the transparent opal switch is swollen in hydrophilic acetic acid, right-handed spirals and helices that exhibit angularly dependent colors from Bragg diffraction are formed. When the transparent opal switch is swollen in hydrophobic hexane, left-handed spirals which exhibit angularly dependent colors from Bragg diffraction are formed. When the transparent opal switch is swollen in hydrophobic hexane solvent, a left-handed spiral and helix with an angularly independent bluish color is formed. After deswelling, all switches returned back to the transparent planar state. These color-tunable, reversible spiral and helical opal switches can be useful as mechanical actuators, and electrical devices as well as optical components.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.47-53
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• 2015

In this paper, a novel fluid controlled phase tunable line using inkjet printed microfluidic composite right/left-handed(CRLH) transmission line(TL) is proposed. A CRLH-TL prototype has been inkjet-printed on a paper substrate using silver nano particle ink. In addition, a laser-etched microfluidic channel in poly methyl methacrylate(PMMA) has been integrated with the CRLH TL using inkjet-printed SU-8 as a bonding material. The proposed TL provides excellent phase-tuning capability that is dependent on the different fluidic materials used. As the fluid is changed, the proposed TL can have negative-phase, zero-phase, and positive-phase characteristics at 900 MHz and reflection coefficient is maintained to below -10 dB. The performance of the proposed TL is successfully validated using simulation and measurement results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.1
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• pp.21-28
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• 2012

In this paper, we propose a flexible zeroth-order resonant(ZOR) antenna. Its zero phase constant ensures that the antenna performance is independent of substrate deformation. A composite right/left-handed transmission line is designed based on coplanar waveguide technology to realize the zeroth-order resonance phenomenon. The CRLH is an implementation of metamaterial(left handed material) which is composed of shunt inductance and series capacitance. In order to yield additional circuital parameter, chip inductor and gap capacitor is added, respectively. The proposed ZOR antenna provides good performances: reasonable bandwidth(6.5 %) and peak gain(0.69~1.39 dBi). Simulated and measured results show that the antenna's resonant frequencies and radiation patterns are almost unchanged at different curvature diameters of 30, 50, 70 mm, as well as for a flat surface.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.985-991
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• 2008

This paper presents a novel balanced mixer receiver front-end design based on a metamaterial structure applicable to differential-/common-mode excitation. This metamaterial structure functions as a leaky-wave antenna and provides in-trinsic common-mode suppression. Low LO leakage and high RF to LO isolation are achieved without additional filters for LO and RF paths. The metamaterial is based on a unit-cell which under a differential-mode excitation behaves like a composite right/left-handed(CRLH) metamaterial. In contrast, the metamaterial unit-cell is below cut-off under a common-mode excitation. Experimental results are used to verify the proposed metamaterial's differential-/common-mode characteristics. The metamaterial is integrated with a balanced mixer design resulting in an operation frequency range of $1.96{\sim}2.40$ GHz with an optimum mixer conversion loss of 21.1 dB at 2,4 GHz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2032-2037
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• 2010

This paper describes a design of dual band amplifier using left handed (LHJ) transmission line, which is a part of composite right/left handed (CRLH) transmission line. It is well known that CRLH transmission lines show dual band frequency response. At first, two single-band amplifiers for frequency f1 and f2 are designed, and their matching networks at both amplifiers are synthesized into the dual band matching network by adopting CRLH structure. As an example for proving the validity of the proposed design, a dual band amplifier operating at 1800MHz and 2300MHz is designed, fabricated and measured. The simulation and measurement show that the proposed amplifier operates well at the desired dual bands with the gain of 13.65dB and 19dB at 1850MHz and 2360MHz, respectively, and a good matching performances. In addition, a quite good agreement between the simulation and measurement is observed.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.196-201
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• 2013

In this paper, a dual-mode balanced filter with symmetric coupled composite right/left-handed transmission line is introduced. Unlike the other symmetric structure, this configuration has the ability to operate under both common- and differential-mode excitation. These properties are achievable through providing physical short circuit by means of ground vias at the center of each unit-cell along the symmetry plane of the structure. Because the CRLH unit-cells are operated under both common- and differential-mode excitation, we implemented a balanced filter using these properties. To validity these features, a five-cell four port coupled CRLH-TL is simulated, fabricated and measured and the obtained performances agree with the simulation results under both common- and differential-mode excitation.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.423-429
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• 2015

Objective : The purpose of this study was to investigate the effects of a body alignment correction program on asymmetrically developed squash players. Method : 30 experienced squash players who showed asymmetric body development, after evaluation of moire topography contour line shape, were involved in the experiment. All of them were right-handed and had more than five years of experience playing squash. Variables of body composition, moire topography and EMG were statistically compared between pre- and post- application of the 12-week body alignment correction program. The program consisted of 10-minute, left-handed forehand and backhand drive movements and 36 minutes performing 12 different yoga postures. Results : First, the body alignment correction program showed significant effects on the total weight, body fat percentage, and body mass index of the participants. Second, a decrease of right side inclined angles and an increase of left side inclined angles might result in a higher left-right symmetry rate and a better left-right balance; however the data was not statistically significant. Third, the EMG left-right deviation of erector spinae and latissimus decreased and the erector spinae muscle was thought to be more essential for vertebral movement and left-right asymmetry correction. Conclusion : A body alignment correction program, including yoga and opposite side exercises, could reduce left-right asymmetry.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.95-103
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• 2007

The purpose of this study is Muscle Activity for the Upper Extremity and Morto-Seoinage(Two-handed shoulder throw) according to performance levels and elite judo players (G1) and non-elite judo players, namely university players (G2). To achieve this purpose, three players in G1 whose main special skill was Morote-Seoinage and three university judo players(G2) were selected as comparative group. After analysing this study, conclusions were derived as follows. 1. Muscle activity of musculi membri superious to group of Kuzushi to Tsukuri was the highest in left biceps brachii and right biceps brachii in order. On the other hand, G2 was the highest in left biceps brachii and left flexer carpi randialis in order. 2. Intergral electromyogram of according to the phase showed right triceps 1P of left flexer carpi radialis. G1 and G2 of showed left biceps brachii was the highest in 1P and 2P. As a result, extra training of left flexer carpi radialis and left biceps brachii is needed.

• Journal of the Korea Safety Management & Science
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• v.11 no.1
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• pp.35-41
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• 2009

대부분의 사람들은 의식하지 못하지만 세상은 오른손잡이 중심으로 이뤄져 있기 때문에 왼손잡이가 일상적으로 겪는 불편은 상상외로 많다. 우리가 일상에서 많이 사용하는 연장, 주방기구, 사무용품, 가전제품, 가구, 의류, 악기, 의료기기, 스포츠용품, 공공시설 등 이들 대부분이 오른손잡이에게 맞춰져 있어 왼손잡이들은 자신들의 왼팔을 비틀어서 사용하거나 주손이 아닌 오른손으로 부자연스런 자세로 사용할 수밖에 없다. 이에 따라 왼손잡이는 일상생활에 있어서의 상당한 불편을 느낄 뿐만 아니라 작업 능률의 저하, 재해나 상해를 입을 가능성이 높아질 수 있다. 본 연구는 무작위로 선정된 피설문자에 대한 설문 조사를 통하여 손잡이(handedness)와 관련된 통계수치를 제공하고 왼손잡이인 경우 왼손잡이로서 일상생활에서의 불편함, 작업능률의 저하여부, 오른손잡이 전용제품을 사용하여 상해를 입은 경험 등에 대해 조사하였다. 또한 왼손잡이도 편리하게 사용할 수 있으면 하는 제품이나 공공시설 등에 대한 이들의 주관적인 견해에 대해서도 조사하였다. 이를 토대로 왼손잡이를 위한 공구, 주방용품, 문구용품, 스포츠용품, 사무용품 등에 대하여 현재 적용되어 있는 상품에 대한 고찰과 향후 적용 가능 상품 및 공공시설에 대해 제안하였다.