• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.899-910
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• 2013

This paper presents a novel lateral stability control system for electric vehicle based on sideslip angle estimation through Kalman filter using the integration of a single antenna GPS receiver and yaw rate sensor. Using multi-rate measurements including yaw rate and course angle, time-varying parameters disappear from the measurement equation of the proposed Kalman filter. Accurate sideslip angle estimation is achieved by treating the combination of model uncertainties and external disturbances as extended states. Active front steering and direct yaw moment are integrated to manipulate sideslip angle and yaw rate of the vehicle. Instead of decoupling control design method, a new control scheme, "two-input two-output controller", is proposed. The extended states are utilized for disturbance rejection that improves the robustness of lateral stability control system. The effectiveness of the proposed methods is verified by computer simulations and experiments.

• 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 Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1325-1332
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• 2009

In this paper, we design a 2.4 GHz bio-radar system that can detect human heartbeat and respiration signals with small size and improved noise performance using single circular-polarized antenna and phase-locked loop. The demonstrated bio-radar system consists of single circular-polarized antenna with $90^{\circ}$ hybrid, low-noise amplifier, power amplifier, voltage-controlled oscillator with phase-locked loop circuits, quadrature demodulator and analog circuits. To realize compact size, the printed annular ring stacked microstrip antenna is integrated on the transceiver circuits, so its dimension is just $40\times40mm^2$. Also, to improve signal-to-noise-ratio performance by phase noise due to transmitter leakage signal, the phase-locked loop circuit is used. The measured results show that the heart rate and respiration accuracy was found to be very high for the distance of 50 cm without the additional digital signal processing.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.2
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• pp.61-71
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• 2018

Existing radio positioning systems have a drawback that the attitude of user's tag is difficult to be determined. Although forward link angle of arrival (FLAOA) technology that uses measurements of array antenna arranged in a tag among the angle of arrival (AOA) technologies can estimate attitude and positioning of tags, it cannot extend the estimated results into three-dimensional (3D) results due to complex non-linear model displayed because of the effects of 3D positioning and attitude in tags. This paper proposed a radio navigation technique that determines 3D attitude and positioning via FLAOA / time of arrival (TOA) integration. According to the order of determining attitude and positioning, two integration techniques were proposed. To analyze the performance of the proposed technique, MATLAB-based simulations were used to verify the performance. The simulation results showed that the first proposed method, TOA-FLAOA integrated technique, showed about 0.15 m of positioning error, and $2-3^{\circ}$ of attitude error performances regardless of the positioning space size whereas the second method, differenced FLAOA-TOA integrated technique, revealed a problem that a positioning error became larger as the size of the positioning space became larger.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.128-134
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• 2012

The performance evaluation and fabrication of integrated-optic electric-field sensor utilizing $Ti:LiNbO_3$ asymmetric Mach-Zehnder intensity modulator with a push-pull lumped electrode and a plate-type probe antenna to measure an electric field strength is described. The modulator has a small device size of $46{\times}7{\times}1\;mm$ and operates at a wavelength $1.3{\mu}m$. The devices are simulated based on the BPM software and fabricated utilizing Ti-diffused $LiNbO_3$ channel optical waveguides. The minimum detectable electric field is 1.02 V/m and 6.91 V/m, corresponding to a dynamic range of ~35 dB and ~10 dB at the frequencies of 500 KHz and 5 MHz, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.77.2-77.2
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• 2015

Recently, metamaterials attracted much attention because of the potential applications for superlens, cloaking and high precision sensors. We developed several dielectric metamaterials for enhancing antireflection or light trapping capability in solar energy harvesting devices. Colloidal lithography and electrochemical anodization process were employed to fabricate self-assembed nano- and microscale dielectric metamaterials in a simple and cost-effective manner. We improved broadband light absorption in c-Si, a-Si, and organic semiconductor layer by employing polystyrene (PS) islands integrated Si conical-frustum arrays, resonant PS nanosphere arrays, and diffusive alumina nanowire arrays, respectively. We also demonstrated thin metal coated alumina nanowire array which is utilized as an efficient light-to-heat conversion layer of solar steam generating devices. The scalable design and adaptable fabrication route to our light management nanostructures will be promising in applications of solar energy harvesting system. On the other hands, broadband invisible cloaks, which continuously work while elastically deforming, are developed using smart metamaterials made of photonic and elastic crystals. A self-adjustable, nearly lossless, and broadband (10-12GHz) smart meatamaterials have great potentials for applications in antenna system and military stealth technology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.193-197
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• 2006

Radiation properties of flush mounted circular patch antennas are investigated. The patch is fed axis-symmetrically by a coaxial cable. Rigorous analysis iscarried out using integral transform and mode matching techniques. The presented method can accommodate a radiating patch, integrated matching section and band pass filter.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.122-127
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• 2012

Post-wall waveguide structures have attracted a great deal of attention for micro- and millimeter-wave applications. One of the waveguide’s applications is a slotted waveguide array. In order to design the slotted array, the characteristics of a slot unit alone on the post-wall waveguide should be investigated. In this paper, a method for extracting the S-parameters of a unit slot is proposed. This simple method requires only two kinds of waveguides: waveguides without a slot unit and waveguides with a slot unit. Three kinds of slot units are fabricated, and the extracted results show a high level of agreement with predicted (simulated) results. With this method, the equivalent slot length can also be found.

• ETRI Journal
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• v.32 no.5
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• pp.827-830
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• 2010

For an adaptive cruise control (ACC) stop-and-go system in automotive applications, three radar sensors are needed because two 24 GHz short range radars are used for object detection in an adjacent lane, and one 77 GHz long-range radar is used for object detection in the center lane. In this letter, we propose a single sensor-based 24 GHz radar with a detection capability of up to 150 m and ${\pm}30^{\circ}$ for an ACC stop-and-go system. The developed radar is highly integrated with a high gain patch antenna, four channel receivers with GaAs RF ICs, and back-end processing board with subspace based digital beam forming algorithm.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.272-275
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• 2001

본 논문에서는 안테나의 위치를 원격에서 제어하고 안테나의 상태를 실시간으로 모니터링할 수 있는 안테나 구동 시스템을 설계하였다. 안테나 구동 시스템은 안테나 포시셔너와 호스트 컴퓨터에서 운용되는 종합관리 소프트웨어로 구성된다. 일반적으로 안테나 포지셔너와 호스트컴퓨터는 멀리 떨어져서 설치가되며 모뎀을 통하여 데이터를 전송하므로, 데이터의 신뢰성을 높이기 위하여 안테나 포지셔너와 호스트컴퓨터간에 주기적인 통신이 이루어지도록 설계하였으며 또한, 데이터 전송 프레임에 오류 검사 바이트를 추가하였다. 종합관리 소프트웨어는 사용자의 편리성을 높이기 위하여 윈도우즈 환경에서 운용되도록 설계하였으며 전자지도에 표시되는 위도, 경도정보를 이용하여 안테나 포지셔너의 구동명령을 계산하고, 사용된 정보를 데이터베이스에 저장할 수 있도록 설계하였다.