• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.5
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• pp.396-401
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• 2017

In this paper, we propose a solution for interference with Bluetooth when connecting Bluetooth and other devices. The random frequency hopping technique is a technique of generating a hopping pattern using the entire Bluetooth channel without considering the interference of the wireless LAN. The proposed adaptive frequency hopping technique is a technique for generating a hopping pattern of Bluetooth channel considering periodic carrier sensing of Bluetooth and considering WLAN interference. Simulation results show that the use of adaptive frequency hopping reduces the packet error rate as the Bluetooth carrier sensing interval decreases even in the congestion of WLAN interference. Especially, the frequency hopping technique improves the average packet error rate by about 13% compared to the adaptive frequency hopping technique.

• Current Optics and Photonics
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• v.1 no.6
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• pp.587-597
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• 2017

The extraction of the valid measurement region from the interference fringe pattern is a significant step when measuring gear tooth flank form deviation with grazing incidence interferometry, which will affect the measurement accuracy. In order to overcome the drawback of the conventionally used method in which the object image pattern must be captured, an improved segmentation approach is proposed in this paper. The interference fringe patterns feature, which is smoothed by the nonlinear diffusion, would be extracted by the structure tensor first. And then they are incorporated into the vector-valued Chan-Vese model to extract the valid measurement region. This method is verified in a variety of interference fringe patterns, and the segmentation results show its feasibility and accuracy.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.111-116
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• 2008

Radar system must estimate exactly quickness and target in interference channel. Because interference of radio channel is multipath channel by artificial structure and nature structure. signal estimation is difficult. As long as, get rid of interference signal have been study digital beamforming, adaptive array antenna and so on. In this paper, proposed SPT-SALCMV beamforming algorithm get rid of coherent interference algorithm and adaptive array antenna. Adaptive array forms null pattern and reduces gains for direction of interference signal. And estimate signal that want by keeping gains of beam pattern changelessly to target signal direction. In this paper, proposed SPT-SALCMV algorithm was exactly received position of target. But general SPT-LCMV algorithm resulted beam error about 30degrees. Therefore, proved that SPT-SALCMV algerian that propose in this paper is more excellent than genaral SPT-LCMV algorithm.

• 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.

• Proceedings of the IEEK Conference
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• summer
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• pp.339-342
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• 2004

In this paper, we investigated methods to reduce SAR(Specific Absorption Rate) value with EMI(Electromagnetic Interference) paint distribution on front case of mobile handset. Simulations for several different EMI patterns were carried out. For the purpose of modeling, we used 3 dimensional CAD(Computer Aided Design) program, `Pro-engineering'. SAR simulation was done with SEMCAD, simulation platform for electromagnetic compatibility antenna design and dosimetry. In order to distinguish the individual pieces and to enable an assignment of the different material properties, each subfile was imported separately. In simulation, folding angle was set to $142^{\circ}.$ If we vary folding angle, different SAR value will be obtained. Among the tested EMI paint patterns, the hairpin pattern showed the best performance, i.e. the decrease efficiency of $16.5\%$ and horizontal-direction zigzag pattern showed the decrease efficiency of $12.2\%$ when we set the completely removed pattern as reference.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.64-76
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• 2001

In this paper, A simple image hologram encryption and decryption technique based on the principle of interference are proposed. The technique using the photorefractive material for getting a stable interference pattern is also proposed. And combine these two techniques, I would like to implement a stable optical information security system. In the encrypting process, I would generate binary phase hologram which can reconstruct original image perfectly, and regard this hologram as original image to be encrypted image. And then the hologram is encrypted as randomly generated binary phase image. Reference image is also generated from the encrypted image by applying interference rule. In the decrypting process, I can get a interference intensity by interfering the reference image and the encrypted image in the interferometer. and transform inferference intensity information into phase information. I recover original image by inverse Fourier transforming the phase information. In this process, the intensity information generated by interference of two images is very sensitive to external vibrations. So, I would like to get a stable interference using the characteristic of SPPCM(self pumped phase conjugate mirror) in photorefractive materials, especially BaTiO₃.

• Korean Journal of Oriental Medicine
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• v.1 no.1
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• pp.273-287
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• 1995

Moire topography, a simple technique for three-dimensional quantitation, was used to provide interference fringe photographs of the human back with sufficient accuracy to be used for detecting patient with asymmetry due to scoliosis, the disease of cervix and lumbar, muscle dysfunction. Contour lines are a suitable and widely accepted method of describing a three-dimensional surface. In the moire technique, contour lines of an object are produced as interference fringes while the object is illuminated by a spotlight through a special grating. The fringe pattern is produced by the interference of the grating and its shadow on the object. A photograph of a moire pattern on the human back will permit an assessment of the overall body shape and the symmetry of the back. This study uses shadow moire topography. Moire topography provides a non-invasive technique for quantifying the shape of the human body. In the use of moire topography for the Oriental Medicine Diagnosis, the strength of moire lies in the ablility to detect change due to deformity of human body.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.130-135
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• 1999

The main scale of linear encoder greatly effects on the precision of displacement measurement. Especially when needing the long range measurement the length of main scale should be increased accordingly. In this paper we propose a linear encoder that uses laser interference pattern as main scale for long range measurement. The linear encoder is similar to Michelson interferometer excepting that the reference mirror is tilted so as to obtain interference fringe pattern and a grating panel is attached on a quadratic photo diodes. Four kinds of grating having phase difference of 0. $\pi$/4, $\pi$/2, 3$\pi$/4 are arranged on the panel. The experimental results show that signals of quadratic photo diode A, B, {{{{ {-}atop {A } }}}} and {{{{ {- } atop {B } }}}} are cosine wavelike and successive signals have phase difference of $\pi$/4 each other. So the proposed method can achieve improved measurement resolution.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.271-274
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• 2002

The 3-D measurement using interference pattern projection is very attractive because of its high measuring speed and high sensitivity. When a sinusoidal amplitude grating was projected on an object, the surface-height distribution of the object is translated into a phase distribution of the deformed grating image. The patters was generated by a interferometer, and a PZT was used to shift the fringes on the target surface. The phase-acquisition algorithms are so sufficiently simple that high-resolution phase maps using a CCD camera can be generated in a short time. A working system requires a interferometer, a PZT, and a detector array interfaced to a microcomputer. Results of measurements on the diffused test objects are described.

• 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.