• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.95-100
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• 2007

In this paper, a twice folded TEM horn antenna for 70 kV impulse high power system is proposed. The length reduction of 50 % is achieved by folding a conventional TEM horn antenna twice. The array elements are fed by the stripline power divider using the Chebyshev transformer. The power divider feeds four TEM horn antenna elements with an in-phased uniform power, and it covers a wide bandwidth ($150\;MHz\;{\sim}\;768\;MHz$, VSWR<2.0). Considering the air breakdown at peak 70 kV impulse, the proposed antenna maintains the 25 mm gaps between conducting plates. The dimension of the twice folded horn antenna is $1730\;{\times}\;1600\;{\times}\;300$ (mm3), and the operating frequency is from 152 MHz to 750 MHz under 10 dB return loss. The peak gains are measured from 6.77 dBi to 10.70 dBi at $400\;MHz\;{\sim}\;750\;MHz$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.111-118
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• 2005

The shape of vertical pattern of base station antenna affects greatly quality of the communication of not only a service zone but also adjacent cells and then it is an important point to be considered in designing cell coverage. Currently type of vertical patterns to be applied to base station antenna are divided into five classes. In designing antenna, these five classes are applied solely or compositely according to the environment to be used antenna. In this paper, the dual polarized antenna for base station that is with a continuous electrical down tilting and with a shaped beam pattern, that an upper side lobe is suppressed and a lower null is filled, is designed and fabricated for synthesizing of the shape beant the pattern synthesis methods proposed by R. S. Elliott is used sequentially and for the electrical don tilting, the phased array theory is applied. Measured results show the down tilting range from 0° to 14°, the gain of Min. 13.3dBi and the upper side lobe of Max. -23dB. And we verified that upper side lobe is not to vary greatly and null filling performance is favorable overall.

• Journal of IKEEE
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• v.24 no.2
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• pp.536-542
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• 2020

This paper presents a nature-inspired wideband sprout-leaf shaped antenna with end-fire radiation pattern. A sprout-leaf shape angled-radiator was designed for wide beamwidth radiation patterns for motion detection sensors. An extended and truncated ground plane was used as a reflector for end-fire radiation patterns. To feed the balanced radiator, a broadband microstrip (MS) to coplanar stripline (CPS) balun was utilized with excellent amplitude and phase balance. The proposed antenna demonstrates wide frequency bandwidth from 8.5 to 14.5 GHz with wide beamwidth and the radiation efficiency of 90%. The measured gain is from 4 to 5 dBi and front-to-back ratio was 10 to 20 dB. It has been shown that the proposed antenna can be used for imaging sensors, phased array systems, and radars that require a wide bandwidth and a directional radiation pattern.

• Spatial Information Research
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• v.22 no.1
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• pp.27-33
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• 2014

Considering the wide coverage, the transparency from climate condition, Interferometric Synthetic Aperture Radar (InSAR) possesses a great potential for the landcover classification as shown in many precedent researches. In addition to the merits of InSAR products for the landcover classification, the time series analysis of InSAR pairs can provide a highly reliable basis to interpret landcover. We applied such idea with the test site in Mountain Baekdu located on the border between North Korea and China. Since it is recently noted as the potential volcanic activation site, the landcover especially the vegetation distribution information is highly essential to validate the reliability of Differential Interferometric Synthetic Aperture Radar (DInSAR) over Mt. Baekdu. The algorithms combining the auxiliary information from Moderate Resolution Imaging Spectroradiometer (MODIS) to analyze the phase coherence and backscatter coefficient of Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) was established. The results using InSAR signatures from two polarization modes of ALOS PALSAR showed high reliability for mining landcover and spatial distribution.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.85-91
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• 2004

The land mobile antenna for two-way communication using geostationary satellite consists of a transmitting and receiving systems. The transmitting system plays the role of sending the signal to the satellite while the receiving system does the role of receiving signal from the satellite and tacking the target satellite. Especially, the land mobile antenna for satellite communication must be met with the international regulation such as antenna pattern, transmitting power and tracking error to protect the damage of the neighbor satellites. On the other hand, this paper thoroughly examined a receiving system to satisfy a stable satellite tracking performance and antenna pattern specified by the international regulation for Ku-band geostationary satellite.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1128-1136
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• 2012

In this paper, we propose an electrically tilting system based on a null-steering in order to solve the problem of the shadowing loss caused by the mechanically tilted antenna system in mobile services. Especially, we improve the downward shadowing loss by eliminating or moving the vertical beampattern nulls between $-30^{\circ}{\sim}0^{\circ}$ to be able to tilt the downward beampattern between $-10^{\circ}{\sim}0^{\circ}$. The antenna has 14.5 dBi gain and side lobe level (SLL) is lower than -18 dB within downward tilting range. The isolation of polarization is greater than 30 dB when running in electric tilt down to $-10^{\circ}$. To verify this paper, we made the base-station antenna for W-CDMA and beam tilting devices, and verified the performances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.307-311
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• 2012

In this paper, a novel particle swarm optimization method based on IE3D is used to design a mobile communication Microstrip Patch Antenna. The aim of the thesis is to Design and fabricate an inset fed rectangular Microstrip Antenna and study the effect of antenna dimensions Length (L), Width (W) and substrate parameters relative Dielectric constant (${\varepsilon}r$), substrate thickness on Radiation parameters of Band width. When the antenna was designed, a dual-band, dual-polarized antenna was used to secure the bandwidth and improve performance, and a coaxial probe feeding method so that the phased array of antenna is easy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.316-319
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• 2012

In this paper, a novel particle swarm optimization method based on IE3D is used to design a mobile communication Microstrip Patch Antenna. The aim of the thesis is to Design and fabricate an inset fed rectangular Microstrip Antenna and study the effect of antenna dimensions Length (L), Width (W) and substrate parameters relative Dielectric constant (${\varepsilon}r$), substrate thickness on Radiation parameters of Band width. When the antenna was designed, a dual-band, dual-polarized antenna was used to secure the bandwidth and improve performance, and a coaxial probe feeding method so that the phased array of antenna is easy.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.248-255
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• 2009

After several damages by PWSCC were found in the world, USNRC and PNNL(Pacific Northwest National Laboratory) started the research on PWSCC under the project name of PINC. The aim of the project was 1) to fabricate representative NDE mock-ups with flaws to simulate PWSCCs, 2) to identify and quantitatively assess NDE methods for accurately detecting, sizing and characterizing PWSCCs, 3) to document the range of locations and morphologies of PWSCCs and 4) to incorporate results with other results of ongoing PWSCC research programs, as appropriate. Korea nuclear industries have also been participating in the project. Thermally and mechanically cracked-four mockups were prepared and phased array and manual ultrasonic testing(UT) techniques were applied. The results and lessons learned from the preliminary RRT are summarized as follows: 1) Korea RRT teams performed the RRT successfully. 2) Crack detection probability of the participating organizations was an average 87%, 80% and 80% respectively. 3) RMS error of the crack sizing showed comparatively good results. 4) The lessons learned may be helpful to perform the PINC RRT and PSI /ISI in Korea in the future.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.4
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• pp.391-402
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• 2016

Among the various remote sensing sensors compared to the electro-optical sensors, SAR (Synthetic Aperture Radar) is very suitable for assessing damaged areas induced by disaster events owing to its all-weather day and night acquisition capability and sensitivity to geometric variables. The conventional CD (Change Detection) method that uses two-date data is typically used for mapping damage over extensive areas in a short time, but because data from only two dates are used, the information used in the conventional CD is limited. In this paper, we propose a novel CD method that is extended to use data consisting of two pre-disaster SAR data and one post-disaster SAR data. The proposed CD method detects changes by using a similarity weight image derived from the neighborhood information of a pixel in the data from the three dates. We conducted an experiment using three single polarization ALOS PALSAR (Advanced Land Observing Satellite/Phased Array Type L-Band) data collected over Miyagi, Japan which was seriously damaged by the 2011 east Japan tsunami. The results demonstrated that the mapping accuracy for damaged areas can be improved by about 26% with an increase of the g-mean compared to the conventional CD method. These improved results prove the performance of our proposed CD method and show that the proposed CD method is more suitable than the conventional CD method for detecting damaged areas induced by disaster.