• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.270-277
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• 2013

In this paper, we propose a wideband ridge SIW(Ridge Substrate Integrated Waveguide)-to-SIW(Substrate Integrated Waveguide) transition. The proposed transition structure is designed to acquire a wide bandwidth by inserting through via holes at the regular interval for an impedance matching and an E-field mode matching method. The measurement results show a fractional bandwidth is 29.1 % at 20 dB return loss from the center frequency(11 GHz). The maximum insertion loss is 0.49 dB from 9.21 GHz to 12.41 GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.317-322
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• 2005

Synthetic Aperture Radars(SAR) are used mainly for high-resolution imaging of the terrain. This paper describes the 16$\times$16 array antenna designed for an X-band, automobile-based SAR(AutoSAR) system. This antenna has the structure of several layers such as radome, radiators, slots, feed network, and honeycomb cores. Each layer is adhesively bonded to meet different combination of structural and electrical design requirements. Using the Strip-Slot-Foam-Inverted-Patch(SSFIP) structure and dogbone slots, a wide bandwidth and a structural hardness were achieved. Measurement results were compared with simulation results. It was observed that the SAR antenna had a bandwidth of 1.7 GHz, side-lobe levels of less than -20 dB, half-power beamwidth of 5$^{\circ}$, and gains of 25.0 dBi. The observed results show that the designed array antenna is suitable for the broadband AutoSAR system.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.91-94
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• 2003

In this paper, we achieve implementation of a Time-Frequency Domain Reflectometry(TFDR) system through comparatively low performance(100MS/s) PCI extensions for Instrumentation(PXI). The TFDR is the general methodology of Time Domain Reflectometry(TDR) and Frequency Domain Reflectometry(FDR). This methodology is robust in Gaussian noises, because the fixed frequency bandwidth is used. Moreover, the methodology can get more information of the fault by using the normalized time-frequency cross correlation function. The Arbitrary Waveform Generator(AWG) module generates the input signal, and the digital oscilloscope module acquires the input and reflected signals, while PXI controller module performs the control of the total PXI modules and execution of the main algorithm. The maximum range of measurement and the blind spot are calculated according ta variations of time duration and frequency bandwidth. On the basis of above calculations, the algorithm and the design of input signals used in the TFDR system are verified by real experiments. The correlation function is added to the TDR methodology for reduction of the blind spot in the TFDR system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1183-1187
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• 2005

In this paper, a weathercock-shaped microstrip patch antenna for application in 5.25GHz band wireless LAN is designed and fabricated. To obtain sufficient bandwidth in VSWR<2, the T-slot is inserted on the patch, the coaxial probe source is used. The measured result of fabricated antenna obtained 350MHz or about $7.62\%$ bandwidth in VSWR<2 referenced to the center frequency, the gain of 5.25${\~}$6.70dBi. The experimental 3-dB beam width is shown to be broad across the pass band in azimuth and elevation at $80.32^{\circ}$ and $83.88^{\circ}$, in several.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.65-71
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• 2009

In this paper, we propose an aircraft on-glass antenna for FM radio reception. To obtain broad matching bandwidth, we employed a multiple loop as the basic antenna structure, and the shape of the loops mimics the frame of a window in order to ensure pilots' field of view as large as possible. The detailed design parameters of the multi-loop structure were determined using a Pareto genetic algorithm with a full wave EM simulation tool. The optimized on-glass antenna was built and installed on a Korean utility helicopter (KUH) The measurement results showed a half power matching bandwidth of about 63.3 %, average vertical bore-sight gain of about -12.98 dBi in the FM band.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.4886-4907
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• 2019

The use of mobile devices is increasing in multimedia applications. The multimedia contents are delivered to mobile users over heterogeneous networks. Due to fluctuation in bandwidth and user mobility, the service providers are facing difficulties in providing Quality of Service (QoS) guaranteed delivery for multimedia applications. Multimedia applications depend on QoS parameters such as delay, bandwidth, and jitter to offer better user experience. The existing schemes use the single source and multisource delivery but are unable to balance between stream quality and network congestion for mobile users. We proposed a Quality Oriented Multimedia Content Delivery Scheme (QOMCDS) for the mobile cloud to deliver better quality multimedia contents for the mobile user. The multimedia contents are delivered to the mobile device based on the device's parameters and network environment. The objective video quality assessment models like Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), and Video Quality Measurement (VQM) are used to measure the quality of the video. The client side Quality of Experience metric such as Startup delay, Rebuffering events, and Bitrate switch count was used for evaluation. The proposed scheme is evaluated using dash.js and is compared to existing schemes. The results show significant improvement over existing multimedia content delivery schemes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.194-198
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• 2004

This paper presents a broadband compact microstrip antenna design with four U slots on the ground plane by using of genetic algorithm. FDTD method is used as fitness function for antenna analysis, and length of rectangular patch, length of ground plane slot, distance from center point to feed point is used as optimization parameter for maximum bandwidth and minimum size. The measurement result of implemented antenna present 10 dB bandwidth of 15.63 ％ and peak gain of 3.61 dBi in the 2.445 GHz, and antenna has a reduced patch size of 54.8 ％ compare with normal microstrip antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.996-1005
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• 2000

This paper proposed a novel broadband ceramic dielectric antenna by improving the conventional broadband technique that very high permittivity material is attaching to one side of low permittivity material. The broadband ceramic dielectric antenna can be designed by using our proposed method, and it overcomes the disadvantage of narrow bandwidth problem. For the proposed ceramic dielectric antenna, a 10 dB return-loss bandwidth of 33.9% has been achieved. The measurement and numerical results(Finite Element Method) are performed and confirmed to a good agreement with each other. The proposed ceramic dielectric antenna is designed and implemented to extend enough the coverage of dual band (PCS+IMT-2000).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.625-632
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• 2002

In this paper, a wide band modified inverted-F type antenna printed on a high dielectric ceramic material is designed and fabricated. This antenna is designed to have optimum antenna characteristics analyzing the effects of design parameters such as printed antenna pattern, ceramic dielectric material dimension and dielectric constant on antenna characteristics using the commercial simulation tool HFSS. The fabricated antenna's width, length and height are 8 mm, 8 mm and 3 mm, respectively. Measurement results show that it has -10 dB bandwidth of 270 MHz which satisfies the IMT-2000 bandwidth required for handset and that its maximum radiation gain is 2 dBi.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.50-56
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• 2014

This paper describes the design, fabrication, and measurement of a 4-port femtocell MIMO antenna for LTE 700MHz(Band12, 13, 14, 17, 28, 44) applications. Based on microstrip patch antenna, an impedance matching is achieved by short pin. In order to obtain sufficient bandwidth and isolation between antenna elements in a limited dimension, a cross decoupler is used. With a Voltage Standing Wave Ratio (VSWR)${\leq}2$, the measured result of the fabricated antenna provides 105MHz(0.698~0.803MHZ) bandwidth and shows the gain with 1.97dBi and isolation above 13dB. As one of the key parameters for MIMO performance evaluation, correlation coefficient of MIMO is achieved within 0.2.