• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.25-27
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• 2010

This paper presents a gain and phase mismatch calibration technique for an image-reject RF receiver. The gain mismatch is calibrated by directly measuring the output signal amplitudes of two signal paths. The phase mismatch is calibrated by measuring the output amplitude of the final IF output at the image band. The calibration of the gain and phase mismatch is performed at power-up, and the normal operation of the RF receiver does not interfere with the mismatch calibration circuit. To verify the proposed technique, a 2.4-GHz Weaver image-reject receiver with the gain and phase mismatch calibration circuit is implemented in a 0.18-${\mu}m$ CMOS technology. The overall receiver achieves a voltage gain of 45 dB and a noise figure of 4.8 dB. The image rejection ratio(IRR) is improved from 31 dB to 59.76 dB even with 1 dB and $5^{\circ}$ mismatch in gain and phase, respectively.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.4
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• pp.13-22
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• 2018

In this paper, double encryption technology of image based on scramble operation and phase-shifting digital holography is proposed. For the purpose, we perform first encryption digitally using scramble operation for the to be encrypted image, and perform phase modulation to the first encrypted image. Finally, we get the secondary encryption information through the interference between the phase-shifted reference wave and phase modulated image. The decryption process proceeds in the reverse order of the encryption process. The original image is reconstructed by digitally decoding the two encrypted images through a phase shift digital holography technique that appropriately performs arithmetic processing, phase-demodulating and then using the encryption key information used in the scramble operation. The proposed cryptosystem can recover the original image only if both the key information used in the scramble operation, the distance information used in the phase shift digital holography technique, and the wavelength of the light source are known accurately.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1733-1740
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• 2001

A monolithic 5 GHz image reject mixer using a 0.5-m GaAs MESFET technology is designed and simulated. The Mixer exhibits a 13.56 dB down-conversion gain, a SSB (Single SideBand) noise figure of 11.91 dB, an input IP3 (third order intercept point) of -3.73 dBm and a PldB (1-dB compression point) of -11.0 dBm. The critical issue in the image reject mixer is the phase accuracy and magnitude balance of the 90 phase shifting network. The proposed image reject mixer realizes a 90 phase shifter on chip. This phase shifting network does not need any phase adjusting to achieve the phase error specification of 3 over a frequency range from 800 MHz to 1GHz. The simulated overall image rejection ratio is better than 50 dB.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.958-961
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• 1999

A new image encoding and identification scheme is proposed for security verification by using CGH(computer generated hologram), random phase mask, and correlation technique. The encrypted image, which is attached to the security product, is made by multiplying QPH(quadratic phase hologram) using SA(simulated annealing) algorithm with a random phase function. The random phase function plays a role of key when the encrypted image is decrypted. The encrypted image could be optically recovered by 2-f system and automatically verified for personal identification. Simulation results show the proposed method cand be used for the reconstruction and the recognition of the encrypted. Image.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.1-6
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• 1997

This paper presents the theoretical derivaion relating and image correlationcoeffcient capable of assessing image quality, with phase-error variance in antenna aperture domain. We show that when the phase-error variance of a range bin selected as an adaptive beamformer is known, the quality of the reconstructed image is predictable and moreover, the resultant correlation coeffcient is obviously greater than the derive dlower boudn. To support the derivation, real data are used for image formation where the dominant scatterer algorithm (DSA) is applied for phase compensations.

• Journal of the Korean Society of Visualization
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• v.2 no.1
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• pp.39-45
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• 2004

A time-resolved two-phase PIV system using a single camera has been developed, which introduces a method of image separation into respective phase images, and is applied to freely rising single bubble. Gas bubble, tracer particle and background have different gray intensity ranges on the same image frame when reflection and dispersion in the phase interface are intrinsically eliminated by optical filters and fluorescent particles. Further, the signals of the two phases do not interfere with each other. Gas phase velocities are obtained from the separated bubble image by applying the two-frame PTV. On the other hand, liquid phase velocities are obtained from the tracer particle image by applying the cross-correlation algorithm. As a result, the bubble rises rectilinearly just after it is released from an injector and then has a zigzag motion in the far field. From the trajectory of the bubble, it is found that the period of the zigzag motion is closely related to the vortex shedding although the wavelength of it varies along its movement.

• Journal of Science of Art and Design
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• v.1
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• pp.63-93
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• 1999

This treatise begins with finding a meaning of Paul Klee's . It is pretty simpleto choose the square of Klee. The most important formative language for twenty century is abstraction. The element of speaking for abstraction issquare. The artists are trying to contain the nature and universe in the square. The role of magic square consisting with small squares of Klee is crystallized. The other side, the test of this study is a method analysis. The method analysis is changing while concept and style have been changing according to a period. The existing method analysis is an iconology used many times in Art history. This treatise introduces France symbolists, Bernard Cocula and Claude Peyroutet's analysis of a meaning of image(Semantique do l'image) who were applied to Modern Art. based on Iconography. It also applies to analysis of artwork of Klee. Cocula's is developed from one phase to five phase step by step. The first phase deals with an appearance of artwork. Subsequently, the second phase is directly adjacent to personal feeling and impression. This is an adequate method for image study in the analysis of modern arts. This phase makes it a rule to enjoy talking with artworks above all. The third phase begins with this question 'What do you see? (que voyons-nous?).' The applies exhaustively and strictly to complicated image artworks which need an elaborate analysis. It is very hard but audiences must try to maintain neutrality in front of artwork because cord formation and interpretation should be formed objectively. The meaning analysis and interpretation of the forth phase begins with this question 'what is the image rouse'(qu'evoque cote image?).' This phase is the most important in a process of symbolic analysis. The audience investigates personal elements and common elements. The fifth is synthetic analysis and interpretation phase. The synthesis is last phase and it reaches a valuation and a conclusion. Namely, the synthesis phase makes up synthesis conclusion, summarizes image character, and completes value adjudication. Sometimes it completes no conclusions in a silence. This study found a new possible analysis example from Paul Klee's work. The study emphasizes square analysis and interpretation and uses . The analysis of artwork by Cocula's is an example of the most important work of Klee's three artworks. The first analysis of artwork is and the second one is . The third one is . In these analyses, Klee usedmagic square 'to make natural pictorial element and to explain organic living things.'

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.249-254
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• 2003

In this paper, we propose an improved image encryption and decryption method using a phase-encoded virtual image and interference. An original image is simply decrypted by interfering a reference wave with the wave passing through a decrypting key and the encrypted image, where every image has grey level. The proposed encryption is performed by the multiplication of an encrypting key and a phase-encoded virtual image which dose not contain any information for the original image. Therefore even if unauthorized people analyze the encrypted image, they cannot reconstruct the original image. Also grey image encryption can improve the encryption level compared to binary image encryption. Computer simulation and optical experiments confirmed that the proposed technique is a simple for optical encryption.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.165-168
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• 2004

This paper propose a target tracker using phase correlation. The tracker consist of a pre-processing module, a translation estimation module based on phase correlation, a fine motion estimation module applied when confidence rate could not fulfill a threshold value and a reference image update module. The fine motion estimation module measure the shift, rotation and scale of input image compared to reference using Fourier-Mellin transform. Proposed tracker was tested its accuracy and robustness using some real indoor and outdoor image sequences.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.58-59
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• 2003

We propose the optical encryption system using two divided image to hide the original image and a joint transform correlator. The encryption procedure is performed by the Fourier transform of the product of each phase encoded image (divided phase images) and the same random phase image which is generated by computer processing. An autocorrelation term of joint transform correlator contributes to decrypt the original image. This system will be used in optical certification.