• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.709-710
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• 2024

Super resolution에서 High-frequency Details를 개선하는 것이 최근 문제이다. 기존에는 Super resolution을 Regression task로 접근하므로써 L2 Loss를 사용하여 이미지가 흐릿하게 되었다. 이를 해결하기위해, Classification task로 바꾸므로써 Cross Entropy Loss을 적용하여 Cross-entropy Super-resolution (CS)를 설계한다. CS를 통해 선명도와 Details이 개선되지만, 저주파의 CE Loss 학습으로인한 Black Artifacts가 발생한다. 그래서, L2 Loss는 저주파와 같이 큰 신호에 더 초점을 맞추므로, 성능 개선을 위해 저주파를 L2 Loss에서, 고주파를 CE Loss에서 학습시킨 Frequency-specific Cross-entropy Super-resolution (FCS)을 제안한다. 우리는 왜곡에 강하며 Human의 인식과 유사한 측정지표인 Learned Perceptual Image Patch Similarity (LPIPS)로 평가한다. 실험한 모든 데이터 셋에서 우리의 FCS는 Baseline보다 LPIPS가 약 1.7배 정도 개선되었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.75-80
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• 2003

This paper presents novel compact circularly polarized(CP) operation of a annular ring slot antenna with a 45$^{\circ}$truncated in the patch and a cross-slot of unequal slot lengths. A simple configuration based on a cross-slot of unequal slot lengths on the annular ring patch is adopted to realize a small-size element antenna and used a proximity coupled feed method. Experimental results show that much wider impedance bandwidth of 7.74 % and axial ratio bandwidth of 1.9 % in GPS band(1.5 GHz).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1178-1183
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• 2004

In this paper, a novel microstrip patch antenna with switchable polarization is proposed. The proposed antenna has a simple structure, consisting of a square radiating patch, a pair of L-type spur-lines, and a microstrip line feed. It can produce either linear polarization or circular polarization by setting the diode on or off From the measured results, low cross polarization levels when operated in the linear polarization, and good axial ratios in the circular state have been observed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1164-1170
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• 2005

This paper presents a dual-band, dual-polarized microstrip patch antenna with simple dual-probe feed. The inter-port isolation and cross-polarization are greatly improved by designing feed structure with annular gap between patch and feed-probe. Measured results show that the antenna's inter-port isolation and cross-polarization in each -10 dB return loss bandwidth of $1.84\;GHz\~l.93\;GHz$ and $2.62\;GHz\~2.81\;GHz$ are greater than 21 dB, greater than 22.2 dB and greater than 27 dB, greater than 19 dB, respectively. The antenna gain is about 6.9 dBi in both frequency bands.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1138-1147
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• 1999

In this paper, two types of $2\times2$ Rx/Tx microstrip patch antenna are proposed to implement Ku-band satellite communications. The single-fed dual resonance patch antenna as the first type derives perpendicular polarizations at two resonant frequencies from a single patch radiator, using aperture coupling via a bended single-feeding line and a cross-shaped slot. The double-fed dual resonance patch antenna as the second type implements dual resonance with mutually orthogonal polarizations by mixing the two feeding mechanisms of the microstrip line and the aperture coupling. Especially, in the double-fed dual resonance antenna case, air-gap is introduced to broaden the bandwidth. Through measurement, each of the two types of antenna was verified to function properly both Rx and Tx. The double-fed dual resonance antenna shows excellent performance in the bandwidth and the crosspolarization characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.475-485
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• 2010

This paper proposes a novel concept for a microstrip resonator that can function as a filter and as an antenna at the same time. The proposed structure consists of an outer ring, an open loop-type inner ring, a circular patch, and three ports. The frequencies where the proposed structure works as a filter and as an antenna, respectively, are determined primarily by the radius of the inner ring and the circular patch. The measured results show that, when the microstrip resonator operates as a filtering device, this filter has about 15.1 % bandwidth at the center frequency of 0.63 GHz and a minimum insertion loss of 1.5 dB within passband. There are three transmission zeros at 0.52 GHz, 1.14 GHz, and 2.22 GHz. In the upper stopband, cross coupling - taking place at the stub of the outer ring - and the open loop-type inner ring produce one transmission zero each. The circular patch generates the dual-mode property of the filter and another transmission zero, whose location can be easily adjusted by altering the size of the circular patch. The proposed structure works as an antenna at 2.7 GHz, showing a gain of 3.8 dBi. Compared to a conventional patch antenna, the proposed structure has a similar antenna gain. At the resonant frequencies of the filter and the antenna, high isolation(less than -25 dB) between the filter port and the antenna port can be obtained.

• Smart Structures and Systems
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• v.5 no.4
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• pp.329-344
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• 2009

Ultrasonic chaotic excitations combined with sensor prediction algorithms have shown the ability to identify incipient damage (loss of preload) in a bolted joint. In this study we examine a physical experiment on a single-bolt aluminum lap joint as well as a three-dimensional physics-based simulation designed to model the behavior of guided ultrasonic waves through a similarly configured joint. A multiple bolt frame structure is also experimentally examined. In the physical experiment each signal is imparted to the structure through a macro-fiber composite (MFC) patch on one side of the lap joint and sensed using an equivalent MFC patch on the opposite side of the joint. The model applies the waveform via direct nodal displacement and 'senses' the resulting displacement using an average of the nodal strain over an area equivalent to the MFC patch. A novel statistical classification feature is developed from information theory concepts of cross-prediction and interdependence. This damage detection algorithm is used to evaluate multiple damage levels and locations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.27-37
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• 2001

The design, fabrication, and an experimental implementation of the strip patch antenna coupled with a H-shaped aperture arc presented in this paper. The proposed antenna has the wide bandwidth, high gain, and low cross-polarization levels. We measured the VSWR, smith chart impedance characteristic, co/cross polarization pattern, gain, and so on. The measured bandwidth of this antenna is 47.1 %. To reduce the back lobe and increase the gain, when the reflector is used, cross polarization level is below -18.2dB at E-plane and below 25.7 dB at H -plane. The maximum gain at 2.05 GHz is also 10.4 dBi and the 3 dB gain bandwidth with center frequency at 2.17 GHz is 24 %, which is the wide bandwidth. This antenna can find applications in mobile communication, wireless LAN, RF communication system, and so on.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1037-1044
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• 2021

In this paper, we propose DLP(Dual Linear Polarization) array antenna for 3.5 GHz band. The proposed antenna has 1×4 array antenna and design two port network. A cross shape is inserted at the bottom of the patch for impedance matching. The size of each patch antenna is 18.85 mm(W1)×18.85 mm(L1), array antenna is designed on the FR-4 substrate, which is 236.0 mm(W)×60.2 mm(L), thickness (h) 1.6 mm, and the dielectric constant is 4.3. From the fabrication and measurement results, bandwidths of 70 MHz (3.54 to 3.61 GHz) for input port 1, 75 MHz (3.55 to 3.625 GHz) for input port 2 are obtained on the basis of -10 dB return loss and transmission coefficient S21 is under the -20 dB. Also, cross polarization between two port obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1159-1165
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• 2008

In this paper, a single-feed equilateral-triangular microstrip antenna with truncated corners is used for achieving diverse radiation polarization. The proposed antenna is excited by a microstrip line, which is place parallel to an oblique side of the equilateral-triangular patch. Depending on whether the three identically-sized comers of the triangular patch are cut or not, the equilateral-triangular microstrip antenna shows linear polarization(LP) or left-hand circular polarization(LHCP) or Tight-hand circular polarization(RHCP). Based on the equilateral-triangular microstrip antenna with truncated corners, a novel reconfigurable microstrip antenna with switchable polarization sense is also proposed. The proposed reconfigurable antenna has a simple structure, consisting of a corner-truncated triangular patch, a small triangular conductor, and a microstrip line. Using a biased PIN diode between the patch and the small triangular conductor, it can produce LP or RHCP according to bias voltages. From the measured results, low cross polarization level when operated in the linear state and good axial ratio in the circular state are observed.