• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.456-464
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• 2013

Passive sonar in submarine can detect the target in long range and can attack using it. There are many noises which can be received at passive sonar of submarine. When noise received in the sonar it make diverse interference pattern depend on the ocean ambient and movement scenario. Interference pattern can be explained by theory of waveguide invariant. In this paper, analyze the interference pattern according to the relative motions of surface ship and submarine. And analyze the occurrence reason of 2 kinds of interference patterns those are usually display on the submarine console. The results show that if relative speed of submarine and target increase then gradient of interference pattern will increase. And closest point approach of submarine and target decrease then gradient of interference pattern will increase. Bathtube pattern usually appear when target pass though close to submarine and Pinetree pattern appear target pass though above of submarine.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.5
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• pp.348-357
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• 2005

We have tried to analyze the SEMG interference pattern quantitatively and automatically using T/A variables ZC, TN, mSA, mSD, UCA, AIPEA, ACT and NSS. For the analysis, we have carried out experiments on 14 SEMG interference patterns recorded from the biceps brachii, first dorsal interosseus and abductor policis brevis muscles. Emphasis was placed on the following 3 points in the experiments. 1) Suitable amplitude threshold for the automatic detection of the T/A variables. 2) Variation of the T/A variables to varying $\%$MVC. 3) Variation of the T/A variables to the sustained contraction for 30 seconds. Results of the experiments showed that T/A analysis of the SEMG interference Pattern can be effective tools for diagnostic purposes instead of the conventional NEMG method.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.80-86
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• 2005

Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.377-383
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• 1996

Recently, a new technique called Electronic Speckle Pattern Inteferometry(ESPI) has been developed to overcome the drawbacks of existing holography. This technique enable real-time interference fringes to be displayed directly on TV monitor without recourse to any form of photographic processing. This research was carried out for the purpose of applying the vibration analysis method employing Electronic Speckle Pattern Interference technique to the vibration analysis of uniform rectangular cantilever plate, The natural vibration frequencies found by ESPI were in fair agreement with theoretical eigen frequencies acquired using theoretical formula G. B. Warburton proposed.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.98-104
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• 1998

Recently. a new technique called Electronic Speckle Pattern Interferometry(ESPI) has been developed to overcome the drawbacks of existing holography. This technique enable real-time interference fringes to be displayed directly on TV monitor without recourse to any form of photographic processing. This research was carried out for the purpose of applying the vibration analysis method employing Electronic Speckle Pattern Interference technique to the vibration analysis of uniform rectangular cantilever plate. The natural vibration frequencies found by ESPI were in fair agreement with theoretical eigen frequencies acquired using theoretical formula G. B. Warburton proposed.

• International journal of advanced smart convergence
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• v.2 no.1
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• pp.21-23
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• 2013

The antenna pattern in this case has a main beam pointed in the desired signal direction, and has a null in the direction of the interference.The conventional antenna pattern concepts of beam width, side lobes, and main beams are not used, as the antenna weights are designed to achieve a set performance criterion such as maximization of the output SNR.A new direction of arrival estimation method using effects of model errors and sensitivity analysis is proposed. Two subspaces are used to form a signal space whose phase shift between the reference signal and its effects of model error signal. Through simulation, the performance showed that the proposed method leads to increased resolution and improved accuracy of DOA estimation relative to those achieved with existing method. Since a desired signal is obtained after interference rejection through correction effects of model error, the effect of channel interference on the estimation is significantly reduced.

• Journal of Advanced Navigation Technology
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• v.21 no.6
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• pp.593-600
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• 2017

This paper analyzes the performances of direction finding, interference cancellation, and beamforming performance by array antenna pattern measurement distance between the center of array antenna and reference emitter. Array antenna is widely adopted for example as wireless communications, radar, and sonar. In order to use array antenna, array antenna pattern must be known and it can be measured in anechoic chamber. However, the size of anechoic chamber is generally limited. So measurement error of array antenna can be occurred and this could effect performance decrease of direction finding, interference cancellation, and beamforming. It is verified by computer simulation that the performances of direction finding, interference cancellation, and beamforming by array antenna pattern measurement distance.

• The Journal of the Acoustical Society of Korea
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• v.22 no.7
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• pp.554-561
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• 2003

Results of the numerical simulation and experimental data analysis for identification of mode cutoff frequency and estimation of sound speed of seabed from the spectrum of acoustic signal received at fixed source-receiver range are presented. Model simulations for Pekeris waveguide show that the frequency-dependent propagation loss and interference pattern are closely related to mode cutoff frequencies and it could be possible to the identify them from the changes of interference pattern. The concept considered at numerical simulations is applied to signals acquired at sea test. Cutoff frequency and sound speed of seabed are estimated from the interference pattern of measured signal. Propagation loss predicted using the estimated sound speed of seabed as model input parameter shows similar estimation result compared to propagation loss derived from measured data.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.32-40
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• 2015

In this paper, the optimum antenna placement is analyzed by considering the interference between airborne antennas mounted on the unmanned aerial vehicle(UAV). The analysis is implemented by selecting the antennas that the distance and operational frequency band between airborne antennas is close to each other among the omni-directional antennas. The analyzed antennas are the control datalink, TCAS(Traffic Collision & Avoidance System), IFF(Identification Friend or Foe), GPS(Global Positioning System), and RALT(Radar ALTimeter) antennas. There are three steps for the optimum antenna placement analysis. The first step is selecting the antenna position having the optimum properties by monitoring the variation of radiation pattern and return loss by the fuselage of UAV after selecting the initial antenna position considering the antenna use, type, and radiation pattern. The second one is analyzing the interference strength between airborne antennas considering the coupling between airborne antennas, spurious of transmitting antenna, and minimum receiving level of receiving antenna. In case of generating the interference, the antenna position without interference is selected by analyzing the minimum separation distance without interference. The last one is confirming the measure to reject the frequency interference by the frequency separation analysis between airborne antennas in case that the intereference is not rejected by the additional distance separation between airborne antennas. This analysis procedure can be efficiently used to select the optimum antenna placement without interference by predicting the interference between airborne antennas in the development stage.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.113-119
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• 1998

Recently Electronic Speckle Pattern Interferometry(ESPI) has been studied because it has the advantages to be able to measure the whole-field surface deformations of engineering components and materials in industrial areas with noncontact. The speckle patterns to be formed with interference phenomena of scattering light from rough surfaces illuminated by laser light have phase informations of surface deformations. In this study we used this interference phenomena and the phase shifting method to measure the inplane deformations, together with the use of digital image equipment to process the informations contained in the speckle pattern and to display consequent interferograms on TV monitor. FEA was performed before experiments and we obtained good agreement between the experimental results and FEA.