• Journal of Convergence for Information Technology
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• v.10 no.3
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• pp.16-21
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• 2020

This paper describes the jamming characteristics of a stand-off jammer jamming the LPI radar. The LPI radar reduces the side lobes of the receiving antenna to reduce the effect of jamming. It is easy a radar to predict the effect of jamming on a self-protection jammer where the jammer is in the same position as the target. However, for stand-off jammer jamming at different locations from the target, the prediction of jamming effect is complex. In this paper, the jamming effect of LPI radar is analyzed using signal to jamming ratio and burn-through range. Also, when the antenna's side lobe decreases below -30 dB, the stand-off jamming effect in the side lobe direction is weak. So we proposed a new jamming method for the main lobe and analyzed the jamming effect. This study is expected to be useful for the design and operation of aircraft jammers.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.2
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• pp.61-70
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• 1984

This paper examines the array antenna theory, basic relations between the array size (aperture) and its beamwidth and resultant patterns. This paper also provides array antenna system design criteria, mainly maximizing the signal-to-noise ratio (SNR) and its corresponding optimum array structure and weight functions. Explicit new expressions for array performance are also illustrated in terms of the array output SNR. An example is provided for a 37-element planar array to explicitly illustrate the beam-forming and nulling operations of the array. Fundamentals of sidelobe canceller (SLC) systems have been discussed along with a derivation of new SLC equations for optimum weights.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.388-402
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• 2000

The radiation characteristics of leaky antenna from the dielectric-coated conducting cylinder with periodic corrugation are investigated theoretically for the infinite and finite periodic structures. For the infinite periodic structure, mode-matching method is applied. The integral equation is derived for the finite periodic structure by use of the Fourier transform and mode expansion and a simultaneous linear equation is obtained. The influences of the corrugation slot width, corrugation depth, dielectric thickness, cylinder radius, and finite corrugation number on the radiation characteristics (leakage constant, phase constant, and radiation pattern) are investigated. The results of the finite periodic corrugations are compared with those of the infinite extent structure and good agreement is found. To reduce high side lobe levels of the uniform finite periodic structure, tapering process on the beginning and end section of antenna and nonuniform quasi-period slot arrays are considered. Especially, for the corrugation period, width and depth used for a corrugated surface wave antenna, through the proper tapering process, end-fire radiation pattern with reduced side lobe levels is given.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.15-18
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• 2000

회전기에서 발생하는 소음성 잡음의 경우 능동잡음 제어를 이용 진폭이 상대적으로 큰 주기성 저주파 잡음 제어로 상당한 감쇄효과를 얻을 수 있다. 본 논문에서는 주기적 저주파 잡음을 효과적으로 제거하는 부밴드 능동잡음제어 구조를 제안하였다 이 구조에서는 QMF를 이용, 진폭이 큰 주기적 저주파신호를 분리하여 적응측엽제거 원리를 적용하여 저주파 신호를 제거한다. QMF에서 발생하는 지연은 각 필터를 통과한 신호경로에 적응필터를 사용하여 보상하였다. 그리고 적응필터 성능향상을 위해 최적 적응이득을 해석적으로 구하여 사용하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.1
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• pp.39-44
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• 1984

Three types of parabolic antenna to reduce the sidelobes and backlobe are compared to determine the best suppressive effect under same conditions which are side rim loading parabilic antenna, flanged prabolic antenna. The hooded parabolic antenna adhered polyurethan form impregnated carbon powder in shows the best shape of suppressed the side back lobes that is 5 to 10 dB suppression of sidelobe and 15dB suppression of back lobe for E-plane.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.1-11
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• 1999

An immunohisochemical study on the cerebral ganglion of the African giant snail, Achatina fulica. was conducted by applying the AB/AY staining and the avidin-bovine-peroxidase complex staining methods. The followings are the results obtained throughout the study. The cerebral ganglion of Achatina fulica is an ellipsoidal body of 2 x 1 mm in size, which is connected by the cerebral commissure of 1 mm in diameter. The cross-section through the cerebral ganglion, shaped like a butterfly, is divided into the medio-dorsal parts, the latero-dorsal parts, the caudo-dorsal parts, and the lateral lobes. In the medio-dorsal and latero-dorsal parts, the LG cells and the DG cells are found mixed, although the LG cells are dominant. In lateral lobe, however, the Y cells are quite dominant, while the LG cells and the DG cells are seldom found. The LG cells are 20-70 $\mu\textrm{m}$ in sizes and circular or ellipsoidal in shapes. They are stained light green with the AB/AY. 1 - 3 nucleoli are found in karyolymph, where granular chromantins are evenly distributed. In cytoplasm, it is found that the secretory granules are evenly developed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.152-155
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• 2013

In this paper, the reduction of the figure of merit depending on the increased spill-over when the parabolic reflector is cut off partially for low-profile configuration in the satellite broadcast receiving antenna is analyzed. Also for the accurate analysis and simulation, it is considered that the noise temperature is increased due to the effect of ground thermal noise toword the sidelobes and back lobes when the antenna is tracked from $0^{\circ}$ to $60^{\circ}$ in elevation angle, and that the total noise temperature is increased because to the noise figure of LNA. As the results, noise temperature is increased up to about 15K and G/T ratio is decreased to about 2.5dB, when the reflector is cut 35% off partially.

• Journal of Biomedical Engineering Research
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• v.20 no.4
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• pp.503-513
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• 1999

A general expression for the beam patterns of various synthetic aperture(SA) techniques was derived based on a unified SA model. This model was used to analyze and compare the performance of existing SA methods. Based on the theoretical studies, we propose a new synthetic aperture technique that is best suitable for the linear-scan imaging. The proposed method enables dynamic tow-way focusing in real imaging so that the B-mode image resolution can be greatly improved. Compared to the conventional focusing technique, the focused beam pattern by the proposed shows the mainlobe width reduced by half and comparable sidelobe levels. Computer simulation results demonstrated the validity of the theoretical analysis and the proposed SA method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.7
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• pp.571-575
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• 2017

This paper presents a C-band bi-directional T/R chipset in $0.13{\mu}m$ TSMC CMOS technology for phased array antenna. The T/R chipset, which is a key component of phased array antenna, consists of a 6 bit phase shifter, a 6 bit step attenuator, and three bi-directional gain amplifiers. The phase shifter is controlled up to $354^{\circ}$ with $5.625^{\circ}$ phase step for precise beam steering. The step attenuator is also controlled up to 31.5 dB with 0.5 dB attenuation step for the side lobe level rejection. The LDO(Low Drop Output) regulator for stable 1.2 V DC power and the SPI(Serial Peripheral Interface) for digital control are integrated in the chipset. The chip size is $2.5{\times}1.5mm^2$ including pads.

• Animal Systematics, Evolution and Diversity
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• v.9 no.2
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• pp.69-86
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• 1993

The larval stages of Hemigrapsus sanguineus were reared in the laboratory and described with illustrative figures. Five zoeal and one megalopal stages were found in the complete larval development. At 25^{\circ}C.$, the megalopa and the first crab instar were attained in 18 and 31 days after hatching, respectively. The first zoeal larva of H. sanguineus showed the characteristics ~ h i c h coincide with those of the same genus by bearing lateral spines on carapace, B-types of telson and antenna, 1 +5 setae on the endopod of maxillule, and 2 + 2 setae on the endopod of maxilla. Morphological features of H. sanguineus larvae were compared to the previous descriptions of larvae of the same genus and morphological differences among them were discussed.