• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.81-82
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• 2016

In this paper, a design method for a compact log-periodic half-bow-tie dipole array antenna for an operation in UWB band is studied. The proposed antenna is miniaturized by using half-bow-tie shaped dipole elements instead of strip-type dipole elements, which are commonly used in general log-periodic dipole array antenna, and by reducing the element spacing. The effects of the flare angle of the half-bow-tie elements and the element spacing on input reflection coefficient and realized gain characteristics of the proposed log-periodic antenna are analyzed. The optimized antenna is designed on FR4 substrate, and it operates in the frequency band of 3.05-13.96 GHz for a VSWR < 2, which assures the operation in the UWB band.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4095-4100
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• 2011

In this paper, a log periodic bow-tie dipole array (LPBDA) antenna for UWB communications is investigated. Bow-tie shaped dipole elements are used instead of general dipole elements for LPDA antennas and the input reflection coefficient and realized gain characteristics of the LPBDA as a function of a flare angle are analyzed. It turns out that as the flare angle of the bow-tie dipole elements is increased, the lowest operating frequency is shifted toward lower frequency and the operating frequency band is increased, but the average gain is decreased. However, the gain variation of the LPBDA is much decreased and the front-back ratio is improved compared to the LPDA. Standard LPDA and LPBDA with a flare angle of 13 degrees are fabricated on an FR4 substrate with a dielectric constant of 4.4 and a thickness of 1.6 mm. Measured gain for the LPDA ranges from 4 to 6.5 dBi at 3.1 to 10.6 GHz band, while that for the LPBDA is in the range of 4.2 to 5 dBi.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1057-1062
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• 2016

In this paper, a design method for a compact log-perio dic half-bow-tie dipole array antenna for an operation in a UWB band(3.1-10.6 GHz) is studied. The proposed antenna is miniaturized by using half-bow-tie shaped dipole elements instead of strip-type dipole elements, which are commonly used in a general log-periodic dipole array(LPDA) antenna, and by reducing the element spacing. The effects of the flare angle of the half-bow-tie elements and the spacing factor on input reflection coefficient and realized gain characteristics of the proposed log-periodic antenna are analyzed. The optimized antenna is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 2.95-11.31 GHz for a VSWR < 2, which assures the operation in the UWB band. In addition, the length and width of the proposed antenna are reduced to 32.1 % and 18.3 %, respectively, compared to the LPDA antenna.

• ETRI Journal
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• v.34 no.1
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• pp.118-121
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• 2012

In this letter, a miniaturized log-periodic dipole array (LPDA) antenna operating from 1 GHz to 6 GHz is proposed for portable direction finding applications. To reduce the lateral size of an LPDA antenna, bow-tie elements and a top-loading technique are utilized and spacing factor is decreased to reduce the spacing between the LPDA elements. The proposed miniaturized LPDA antenna has the measured gain and front-to-back ratio ranging from 1.2 dBi to 3 dBi and from 7 dB to 22 dB, respectively.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.49-56
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• 2017

This paper proposes a method to improve the left right discrimination performance by eliminating the imaginary target based on the frequency features of the beam pattern for bow array. The beamwidth of the imaginary target is wider than that of the real target. If an azimuth axis is considered as a time axis, the real and the imaginary targets can be assumed as high and low frequencies, respectively. To eliminate the imaginary target which has a low frequency component, we design a cut-off frequency of the High Pass Filter (HPF) using the back-lobe imaginary beamwidth. The real target is estimated by eliminating the imaginary target by applying HPF to the entire power of the beamformer output. Computer simulations show that the proposed method can increase the left right discrimination performance above 8 dB on average.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.33-39
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• 2008

In this paper, a broadband rectangular reflector antenna with 16-array elements for WiBro/WiMAX band(2.3${\sim}$3.5 GHz) is designed, and its radiation characteristics are investigated. The designed antenna is composed of the IBBD(Integrated Balun Bow-tie Dipole) elements and has the feed circuit at the rear of the reflector to reduce the unwanted electromagnetic wave from it. To confirm the broadband characteristics of the designed antenna, test antenna is fabricated and its radiation characteristics are measured, compared with calculated results. The measured results show good agreement with the calculated results. As a result of measurements, 1.8GHz of bandwidth(VSWR<1.6) is achieved at $2.06{\sim}3.89GHz$ and the antenna gain over 10.3 dBi. We confirm that the designed antenna can be used as a broadband antenna for WiBro/WiMAX.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.617-635
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• 2020

The purpose of this study is to discuss how to improve the maneuverability of lifting and diving for underwater vehicle's vertical motion. Therefore, to solve these problems, applied the 3-D numerical simulation, Taguchi's Design of Experiment (DOE), and intelligent parameter design methods, etc. We planned four steps as follows: firstly, we applied the 2-D flow simulation with NACA series, and then through the Taguchi's dynamic method to analyze the sensitivity (β). Secondly, take the data of pitching torque and total resistance from the Taguchi orthogonal array (L9), the ignal-to-noise ratio (SNR), and analysis each factorial contribution by ANOVA. Thirdly, used Radial Basis Function Network (RBFN) method to train the non-linear meta-modeling and found out the best factorial combination by Particle Swarm Optimization (PSO) and Weighted Percentage Reduction of Quality Loss (WPRQL). Finally, the application of the above methods gives the global optimum for multi-quality characteristics and the robust design configuration, including L/D is 9.4:1, the foreplane on the hull (Bow-2), and position of the sail is 0.25 Ls from the bow. The result shows that the total quality is improved by 86.03% in comparison with the original design.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1033-1038
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• 2022

In this paper, the design of a printed dipole antenna fed by broadside coupled striplines (BCS) for the 3.5GHz band is described. The two fins of the bow tie are, respectively, on the two sides of the substrate. The feeding balanced lines adopted for 1×2 array are the BCS. The obtained numerical results are in good agreement with experimental data. Through experiments with printed dipole antennas of various extended angles, the printed dipole antenna exhibits the wide bandwidth in the desired frequency band, which has a bandwidth of 28% for VSWR < 2.0 : 1. And within this bandwidth, This printed dipole antenna achieves a stable radiation pattern. It is found that the narrow band and feeding for array characteristic which is a disadvantage of the conventional printed dipole antenna can be improved. The radiation pattern showed omnidirectional characteristics and the maximum gain was about 4.4dBi.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.107-113
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• 2014

The icebreaking research vessel, ARAON had her second ice trial in the Arctic Sea from 16th July to 12th August 2010. During the voyage, the local ice loads acting on the bow of port side were measured from 14 strain gauges. The measurements were also carried out in ice waters with various ice concentration ratio as well as the icebreaking performance tests. In this study, the ice loads measured during the 'general' operation in ice waters were analyzed. As a first step, the relationship between the location of strain gauges and the ice loads were investigated, and then the possibility for observation of higher ice loads was estimated based on the probability density function. The relationship between the ship speed and the ice load was also investigated. 718 peak stresses data higher than 20 MPa obtained from strain gauges array attached in longitudinally and vertically was analyzed. In general, the ice load increases as the ship speed increases in the low ship speed range, and ice load decreases as the ship speed is greater than a certain speed.