• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.13-18
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• 2019

The domestic overhead transmission lines use a vertical configuration and reverse phase arrangement, but when there is a limitation in steel tower height because the transmission lines pass a height limit zone or special zone, an application of triangular arrangement is necessary, and a study on the optimal phase arrangement to minimize inductive interference for this is necessary. If conductor arrangement are changed, the action of electrostatic induction and electromagnetic induction becomes different from before changes, so the changed conductor arrangement should be reviewed in terms of inductive interference. So this paper presents an optimal phase arrangement to reduce inductive interference by calculating electrostatic induction and electromagnetic induction according to conductor arrangement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.211-216
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• 1986

This paper presents theoretical analysis and experimental results on an improved interference rejection circuit in the presence of continuous wave interference at center frequency, particularly in a wide-band communication systems. This circuit is based upon a phase locked loop for estimating the CW interference phase and the MSE technique to minimize the estimation error. Therefore, the introduced rejection circuit that minimized the estimated phase error outperforms the rejection circuit with phase estimation only. As a result of experiment, we confirm that this proposed rejection circuit gives a high degree of interference rejection performances when the input J/S is large.

• Journal of IKEEE
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• v.23 no.1
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• pp.302-305
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• 2019

Non-orthogonal multiple access (NOMA) has been considered for the fifth generation (5G) mobile networks to provide high system capacity and low latency. We calculate the channel capacity for the weak channel user in NOMA and the channel capacity region for NOMA. In this paper, Gaussian mixture channel is compared to the additive white Gaussian noise (AWGN) channel. Gaussian mixture channel is modeled when we assume the practical signal modulation for the inter user interference, such as the binary phase shift keying (BPSK) modulation. It is shown that the channel capacity with BPSK inter user interference is better than that with Gaussian inter user interference. We also show that the channel capacity region with BPSK inter user interference is larger than that with Gaussian inter user interference. As a result, NOMA could perform better in the practical environments.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8C
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• pp.827-834
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• 2003

In this paper, we implemented an optical information security system using computer generated hologram based on the principle of interference and BaTiO$_3$that is photorefractive material. First of all, we would generate binary phase hologram which can reconstruct the original image perfectly, and regard this hologram as the image to be encrypted. And then applying the interference rule to the hologram, encrypted and reference (fkey information) images are generated. In the decrypting process, we can get an interference intensity by interfering the reference image and the encrypted image in the Mach-Zehnder interferometer. and transforming interference intensity information into phase information using LCD(liquid crystal display) and finally 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, we get a stable interference using the characteristic of SPPCM(self pumped phase conjugate mirror) of BaTiO$_3$that is photorefractive material. The proposed method has an advantage of double image encryption by encrypting the hologram of the image instead of original image.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.109-116
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• 2004

Bent-axis piston pump have been commonly used in hydraulic systems because of high pressure level, best efficiency, low shear force on pistons and low operating costs. The other side, they have a few demerits like that they have the relatively high number of moving parts and more discharge pressure ripples. Especially, the discharge pressure ripples bring about vibrations and noises in hydraulic system components such as connecting pipes and control valves, so that these deteriorate the stability and accuracy of the systems. Therefore, the hydraulic systems having the bent-axis piston pump require the methods to reduce the discharge pressure ripples. So, the purpose of this paper is to reduce the discharge pressure ripples by the phase interference of pressure wave and to develope the analysis model of the pumps to predict the discharge pressure ripples. In this paper, the analysis model of the bent-axis piston pump was developed using the AMESim software, and the reliability of that was verified by the comparison with the experimental results. The hydraulic pipeline with a parallel line was used as the method to generate the phase interference of pressure wave. the dynamics characteristics of the hydraulic pipeline with a parallel line were analyzed by a transfer matrix method. the usefulness of the phase interference of pressure wave was investigated through the experiment and simulation. The results from the experiment and simulation said that the phase interference of pressure wave by the hydraulic pipeline with a parallel line could reduce the discharge pressure wave of the pump well. The analysis model of the bent-axis piston pump developed in this paper and the method of the phase interference by the hydraulic pipeline with a parallel line are expected to be helpful to achieve the design of the pump and to reduce the discharge pressure wave of the pump effectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.156-160
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• 2007

Surface plasmon resonance(SPR) has been widely studied for biological and chemical sensing applications. The present study conducts numerical simulation for the single and bimetallic layer SPR configurations by using the multiple beam interference matrix(MBIM) method to investigate the influence of wave interference and complex refractive indices of materials on optical characteristics such as reflectance and optical phase shift which are used for sensing. First, calculated reflectances are compared with experimental data for validation. In addition, in the single film structures this study finds out the appropriate film thicknesses with minimum reflectance for cases of gold film and silver film. For a bimetallic silver-gold film structure, in particular, the bimetallic film thicknesses that has the minimum reflectance are found 36 nm for silver and 5 nm for gold. From the results, the use of phase shift would be useful compared to reflectance in determining the SPR configuration because the phase shift becomes more sensitive than reflectance.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.239-243
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• 1992

We have investigeted the interference phenomena of the second harmonic waves of Nd:YAG laser generated at KDP single crystals and the nitrogen CARS signals. To get the phase difference between the successively generated nonlinear optical signals, a phase shifting unit made of BK-7 glass and a high pressure gas cell are used. Coherence lengths of several samples for the nonlinear signals are measured. Adjusting the thickness of the phase shifting unit where the CARS signals make destructive interference completely, the CARS spectrum of nitrogen suppressed over wide wavelength range is obtained. Also, we have observed the change in degree of suppression of the spectrum for the variation of the thickeness of the phase shifting unit.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.240-245
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• 2014

How well the self-interference cancellation (SIC) technique performs is a primary issue in realizing an in-band full-duplex (FD) wireless communication system. One factor affecting its performance is channel estimation error on the self-interference channel. We propose a new analog SIC scheme which is robust to channel estimation error. It uses phase rotators in the radio frequency (RF) chain. We also derive closed-form equations for the residual self-interference of the proposed and the conventional schemes. The analytical and numerical results show that the residual self-interference under the proposed SIC scheme is less than that using the conventional scheme, even though channel estimation error is present.