• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.58-62
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• 2001

본 논문에서는 IMT-2000 통신방식 중 cdma-2000 방식의 시스템을 이용하여 이동통신 단말기 RF System에 미치는 위상 잡음의 영향성을 분석하였다. cdma-2000의 표준안인 TIA/EIA에서 권고한 IS-98-C 를 기초로 하여 위상 잡음 특성의 요구 조건을 유도하였다. 현재 상용화 된 부품을 이용하여 RF 시스템을 설계하여 위상 잡음 특성을 분석하였고 시스템에 가장 큰 영향을 미치는 oscillator의 위상 잡음의 양을 변화시켜 시스템에 미치는 영향을 Constellation Diagram과 Eye Diagram으로 제시 하였다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.4
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• pp.3-10
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• 2005

Every cell position of a maximum-length 90/150 cellular automata(CA) generates the same pseudo-noise(PN) sequence corresponding to the characteristic polynomial of the CA with a phase shift. Unlike LFSRs, the phase shift is generally different between stages of a CA. In this paper, we propose an algorithm to compute relative phase shifts between stage of a CA. Our algorithm does not need Shank's algorithm to compute relative phase shifts and does not need any previous phase shifts to compute a phase shift. Moreover it is done in time $O(2^n)$.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.182-188
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• 2002

We have analyzed the phase-calculation-error of a three-dimensional shape measurement system using the projection of phase shifted fringe patterns. In this study, we have dealt various errors; an error caused by the variation of quantization levels, an error caused by the defocus of fringe pattern projected images, an error caused by phase-shifting errors, an error caused by the intensity variation of the background and modulation amplitude of fringe pattern projected images during the projection of multiple patterns, an error caused by the distortion of sinusoidal shape of a fringe pattern. The results will contribute to the design of a three-dimensional shape measurment system and give an important meaning to the calculation and the analysis of the accuracy of a system.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.328-334
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• 1999

Methylene blue-sensitized photopolymerizable material based on acrylamide is investigated with two-wave energy coupling experiments. Differently from other studies, self-diffraction oscillations are observed and the grating phase is determined without applying external electric fields, moving nonlinear materials, and phase shifting one of two writing beams. The phase grating showed a phase shift of $\pm$50$^{\circ}$ with respect to the intensity grating. Modified Kogelnik's coupled wave equation considering the mixed gratings of phase and absorption gratings and nonzero spatial phase shifts of the gratings with respect to the intensity interference patterns formed during the two-wave energy coupling is discussed in detail to understand these phenomenon.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.229-236
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• 2008

Recently, multilevel H-bridge inverters have become popular in medium to high power ac drive applications. One of significant advantages of them is low harmonic contents in their input line currents thanks to the transformer with multiple phase-shifted secondary windings. This paper attempts to provide basic guidelines for the design of the phase shifting transformer windings and theoretical analysis of input line current harmonics of H-bridge inverters. The part I provides the derivation of basic relationships between input and output current of the transformer and the relationship between the phase shifting characteristics and design aspects of the transformer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.174-174
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• 2004

본 논문에서는 4변이 고정된 정사각형 알루미늄 평판의 진동 진폭을 측정하기 위하여, 기존의 위상 이동 ESP떼 스트로보스코프식 조사를 적용한 스트로보스코픽 ESPI 기법을 이용하였다. 일반적으로 시간평균 ESPI를 이용하면 진동하고 있는 대상체의 정성적인 진동 패턴을 측정할 수 있다. 그러나 시간평균 ESPI로는 진동하고 있는 대상체의 두께방향으로의 진폭량을 측정하기는 어렵다. 또한 일반적인 위상이동법을 적용시킬 경우, 대상체가 진동을 하게 됨으로써 정확한 진동 진폭을 측정하기 어렵다.(중략)

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.217-224
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• 1994

The combination of both phase-shifting convolution and 2-bit quantization smoothing filter was used to reduce speckle noise from saw-tooth speckle fringes phase map, obtained in phase-shifting speckle interferometer. The phase-shifting convolution showed the noise reduction capability of speckle fringe without destroying edge information across 271 jump. Also, it was shown that the 2-bit quantization smoothing filter was superior to average, low-pass filter and median filter in speeding up smoothing process and enhancing SIN ratio. Finally, a path dependent unwrapping algorithm was used to unwrap a noise reduced 271 modulo speckle phasemap. semap.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2507-2513
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• 2010

In this paper, we show that the shrinking generator with two LFSR whose characteristic polynomials are primitive is an interleaving generator and analyze phase shifts in shrunken sequence. Also for a given intercepted sequence of shrunken sequence, we propose. the method of reconstructing some deterministic bits of the shrunken sequence using phase shifts.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.51-56
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• 1995

일방향 흐름에 표면파가 중복하여 작용할 때 해저면 마찰력의 증가로 토사이동량의 증대가 예상된다. 표면파는 왕복운동 특성을 갖고 있으며, 유속과 해저전단력간의 위상차와 해저잔단력과 토사이동발생 시각간의 위상차가 존재하기 때문에 토사이동량 산정에 많은 어려움이 따른다. 그러나 이렇게 복잡한 현상이 내포되어 있음에도 불구하고 일반적인 기법으로 하천 토사이동량 산정식을 수정하거나 비례상수를 재조정하여 파와 해류에 의한 토사이동량을 산정해 왔다. (중략)

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.516-520
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• 2005

We proposed an efficient phase stepping method for the use in fiber-optic ESPI. To improve phase-stepping accuracy and efficiency, a fiber-optic Michelson interferometer was phase-modulated by a ramp-driven fiber stretcher, resulting in 4$\pi$ phase excursion in the PD interference signal. The zero-crossing points of the signal, which have consecutive $\pi$ phase difference, were carefully detected and used to generate trigger signals for the CCD camera. From the experimental results by using this algorithm, $\pi$/2 phase-stepping errors between the speckle patterns were measured to be less than 0.6 mrad with 100 Hz image capture speed. Also it has been shown that the error from the nonlinear phase modulation and environmental perturbations could be minimized without any feedback algorithm.