• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.8
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• pp.608-614
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• 2018

This paper describes the synthesis method for an adaptive SLB channel, which is robust to interference in the ULA radar system. The SLB channel based on the spatial DLC can be synthesized simply and is effective in blanking the signal coming from the sidelobe. We combined it with adaptive beamforming, which removes the strong interference using its correlation matrix. The adaptive SLB channel would suppress the interference below the noise, so it has good performance in an interference environment. This research will be applicable to planar array systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.541-547
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• 2013

Range resolution is important performance parameter to distinguish a target accurately. The destination of modern radar systems, to overcome the limitations of existing analog radar systems, is to improve the range resolution of the distance with low transmission power. For that reason, the research on pulse compression techniques is briskly studying. In the Receiver, modulation system of transmitted signal which has used in pulse compression technique is divided PM and FM to distinguish a target. In this paper, We analysed and designed the pulse compression signal processing module using the Baker Code which is the one of PM method's.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.43-49
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• 2014

This paper presents a theoretical study of transmission performance for an optical duobinary transmitter employed a Mach-Zehnder modulator and a electrical low pass filter at 40Gbps optical communication links. It depends on the bandwidth of the low pass filter in the transmitter, the optical filter and the filter in the receiver. Also, each filter affected to the various parts of the optical power spectrum. By optimizing the bandwidth of each filter, we could control the side robes and the ripples and improve the dispersion tolerance of the transmission system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.363-368
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• 2003

In this paper, the characteristics of the horn antenna for the high power transfertation system is stuided and several kinds of a horn antenna are compared and finally a conical hem antenna using multi-mode is proposed. In the high power system, the efficiency of power transfer is very important. Therefore the feeding hem of a reflector must have a circular symmetric radiation pattern. And the side lobe must be suppressed to reduce a spillover power loss and interference. By using multi-mode in a circular hem antenna, the whole length can be shorter and the radiation pattern can be adjusted according to the shape and direction of a reflector. This is confirmed by the experiments.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.151-156
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• 1991

In this paper, we propose a new algorithm for designing the R-G filter that has optimum performance in terms of mean square sidelobe level(MSSL) for the Barker code. The advantage of the conventional R-G filter lies in its simple structure so that it can be easily implemented. However, the conventional R-G filter dose not have optimum performances in terms of peak sidelobe level(PSL), mean sidelobe level(MSL), and MSSL. Recently, a(R-G)LP filter of which filter coefficients are obtained by the linear programming algorithm was proposed and known to have optimum performance in PSL. The proposed (R-G)LS filter keeps the simple structure of the conventional R-G filter and has the filter coefficients that minimizes the sidelobe in the least square sense. The analytic results show that the proposed (R-G)LS filter has better performances than the conventional R-G filter in terms of PSL, MSL, and MSSL. Compared with (R-G)LP filter, the proposed (R-G)LS filter has better performances in terms of MSL and MSSL. The proposed filter design algorithm can be applied to the other binary codes such as truncated pseudonoise(PN) codes and concatenated codes.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.5
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• pp.49-59
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• 2022

The SHAPE algorithm has the advantage of being able to shape the pulse spectrum as desired and design it not to distort other characteristics, so it was used in the active sonar pulse design. In this paper, we propose a pulse design using the SHAPE algorithm for a multi-static sonar system to reduce the cross-correlation between frequency-adjacent pulses and prevent the performance degradation of the pulses themselves. The boundary function of the SHAPE algorithm is set to be limited to the pulse bandwidth. As a result of applying the proposed design method to the sinusoidal frequency modulated pulse, the peak cross-correlation level (PCCL), which means the degree of cross-correlation, was reduced by 44.23 dB. Although the PCCL decreased by several tens of dB, no significant change in the ambiguity function was observed, and the integrated sidelobe level (ISL), which means the average value of the side lobe, increased by 11.64 dB.

• The Journal of the Acoustical Society of Korea
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• v.41 no.4
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• pp.446-460
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• 2022

In this paper, we propose an algorithm to improve target detection rate degradation due to direct blast in a bi-static sonar systems with high duty cycle using an adaptive filters. It is very important to suppress the direct blast in the aforementioned sonar systems because it has a fatal effect on the actual system operation. In this paper, the performance was evaluated by applying the Normalized Least Mean Square (NLMS) and Recursive Least Square (RLS) algorithms to the simulation and sea experimental data. The beam signals of the target and direct blast bearings were used as the input and desired signals, respectively. By optimizing the difference between the two signals, the direct blast is removed and only the target signal is remained. As a result of evaluating the results of the matched filter in the simulation, it was confirmed that the direct blast was removed to the noise level in both Linear Frequency Modultated (LFM) and Generalized Sinusoidal Frequency Modulated (GSFM), and in the case of GSFM, the target sidelobe decreased by more than 20 dB, thereby improving performance. In the sea experiment, it was confirmed that the LFM reduced the level of the transmitted direct wave by 10 dB, the GSFM reduced the level of the transmitted direct wave by about 4 dB, and the side lobe of the target decreased by about 4 dB, thereby improving the performance.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1860-1866
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• 2016

Helicopter-related collision accidents with structures mostly occur at landing, especially in a limited visibility environment, which necessitates some secondary equipment like a radar that can generate stationary clutter image. In this paper, we propose an algorithm that makes an image of stationary ground clutter in two dimensional range and azimuth angle domain. We present a mathematical model for the received signals from each clutter patch in the iso range ring and analyze their clutter and Doppler characteristics, assuming that a helicopter-borne radar has a rotational antenna. We propose a filter structure, which suppresses side lobe signal components while extracting a main lobe signal component, and suggest a solution for a problem stemmed from the filtering process. Finally, by conducting a simulation we show the performance of the suggested imaging algorithm on a two dimensional virtual scenario of the topographic clutter.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.3
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• pp.307-317
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• 2019

To develop sustainable new natural anti-aging ingredients from Korean native plants, we investigated the cultivation potential of Nymphoides indica using the eco-friendly aquaponics system, and tested the anti-aging effects from N. indica extracts. N. indica could be grown in aquaponics system using floating leaved deep water culture method, and propagated through rhizome propagation. It was confirmed that the nitrate ($80{\mu}g/mL$), potassium ($63.5{\mu}g/mL$) and water temperature ($25^{\circ}C$) greatly affected the cultivation of the N. indica. In addition, synergistic effects were found when two major components (3,7-di-O-methylquercetin-4'-O-${\beta}$-glucoside & sweroside) were present at more than about $5{\mu}g/mL$. The extract had a significant effect on the recovery of skin cells damaged by environmental pollutant such as $benzo[{\alpha}]pyrene$, ammonium nitrate, formaldehyde. It also suppressed $PGE_2$, $TNF-{\alpha}$ and COX-2, and inhibited the production of MMP-1. Taken together, the results suggested that the standardized extracts of N. indica cultivated in the aquaponics has considerable potential as a new cosmetics ingredient with an anti-aging effect.