• 한국국방경영분석학회지
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• 제31권2호
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• pp.1-12
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• 2005

Defense firms' excess profitability by shifting common overhead costs from non-defense sector to defense sector in the award of cost reimbursement type of defense contracts is a widespread conclusion in prior researches. In this paper, we reviewed cost-shifting incentives in defense-contracting firms and extended the analysis of McGowan and Vendrzyk(2002) by applying modified model to Korea Defense Contracts. We formulated six hypotheses to test the relation of cost-shifting and excess profitability regarding market openness, auditing system, ranking in defense contracts, and firm types(sole defense contractors, sole non-defense contractors, and defense and non-defense mixed contractors). But, we could not find any evidence that defense firms shifted costs from non-defense sector to defense sector for the period 1997-2002. The results suggest that the excess profitability of Korea defense firms may not be from the cost-shifting but from other reasons.

• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.354-364
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• 2012

In this paper, a new 2-step quadrature phase-shifting digital holographic optical encryption method using orthogonal polarization is proposed and tolerance errors for this method are analyzed. Unlike the conventional technique using a PZT mirror, the proposed optical setup comprises two input and output polarizers, and one ${\lambda}$/4-plate retarder. This method makes it easier to get a phase shift of ${\pi}$/2 without using a mechanically driven PZT device for phase-shifting and it simplifies the 2-step phase-shifting Mach-Zehnder interferometer setup for optical encryption. The decryption performance and tolerance error analysis for the proposed method are presented. Computer experiments show that the proposed method is an alternate candidate for 2-step quadrature phase-shifting digital holographic optical encryption applications.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.275-280
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• 2008

We propose a method generating elemental images for the integral imaging using 4-step phaseshifting digital holography. Phase shifting digital holography is a way recording the digital hologram by changing the phase of the reference beam and extracting the complex field of the object beam. Since all 3D information is captured by phase-shifting digital holography, the elemental images for any specifications of the lens array can be generated from single phase-shifting digital holography. In experiment, phase-shifting is achieved by rotating half- and quarter- wave plates and the resultant interference patterns are captured by a $3272{\times}2469$ pixel CCD camera with $27{\mu}m{\times}27{\mu}m$ pixel size.

• Journal of the Optical Society of Korea
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• 제13권2호
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• pp.245-250
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• 2009

We propose a digital holographic interference analysis method based on a 2-frame phase-shifting technique for measuring an optical mirror surface. The technique using 2-frame phase-shifting digital interferometry is more efficient than multi-frame phase-shifting techniques because the 2-frame method has the advantage of a reduced number of interferograms, and then takes less time to acquire the wanted topography information from interferograms. In this measurement system, 2-frame phase-shifting digital interferograms are acquired by moving the reference flat mirror surface, which is attached to a piezoelectric transducer, with phase step of 0 or $\pi$/2 in the reference beam path. The measurements are recorded on a CCD detector. The optical interferometry is designed on the basis of polarization characteristics of a polarizing beam splitter. Therefore the noise from outside turbulence can be decreased. The proposed 2-frame algorithm uses the relative phase difference of the neighbor pixels. The experiment has been carried out on an optical mirror which flatness is less than $\lambda$/4. The measurement of the optical mirror surface topography using 2-frame phase-shifting interferometry shows that the peak-to-peak value is calculated to be about $0.1779{\mu}m$, the root-mean-square value is about $0.034{\mu}m$. Thus, the proposed method is expected to be used in nondestructive testing of optical components.

• 한국정밀공학회지
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• 제15권10호
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• pp.96-102
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• 1998

In this study, the theory and application of phase-shifting shadow moire topography is focused on the non-contact measurement of object surfaces for practical use in the field of production engineering. Shadow moire topography has been studied during last few decades in the area of the optical physics, and now its mathmatical theory has been established. Generally, in case of the classical shadow moire topography, the sensitivity is a few tenths of millimeter in best cases. Here we tried the application of phase-shifting method to the conventional shadow moire topography. But the reference grating and the deformed grating are mutually dependent because it is impossible to obtain uniform phase shifts on the whole Held. Therefore it is difficult to use a phase-shifting method in shadow moire topography. However, it was shown that constant phase-shifting was able to be measured by moving both the grating and light source. Finally we obtained a better result by using this procedure and applied the phase-shifting shadow moire to three dimensional object measurement.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.41-46
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• 2007

This article deals with the design and prototyping of Shift-By-Wire system for an automatic transmission equipped vehicle. In order to manipulate the shifting action electronically, Shift-By-Wire system consists of an electronic shift lever, an electric shift actuator and position sensors. The shift lever is designed to transform the driver's shifting command into an electric signal; it includes the position sensor using non-contact type hall sensor and an additional shifting switch acting as Tip-tronic. For the design of an electric shifting actuator, we investigated the stroke angles and shifting efforts of the manual control lever in each shifting section. And the position sensor of the shifting actuator is designed by using a potentiometer with an optical encoder. Finally the prototype of Shift-By-Wire system was built in a conventional 2.4L class SUV vehicle, and we performed road tests in order to verify its performance.

• 한국통신학회논문지
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• 제40권2호
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• pp.372-379
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• 2015

최근 동영상 압축 표준은 세밀한 움직임 정보를 확보하기 위해 1/4 화소 단위의 움직임 예측 알고리즘을 사용하고 있다. 일반적인 동영상 부호화기에서 사용하는 공간 영역에서의 움직임 예측은 부화소 단위 움직임 예측을 위한 보간 기술의 적용으로 인한 계산량 증가 문제가 발생한다. 본 논문에서는 주파수 영역에서 shifting matrix를 이용한 부화소 정밀도의 움직임 예측 알고리즘을 제안한다. 주파수 영역에서 shifting matrix 알고리즘을 사용함으로써 낮은 계산량으로 부화소 움직임 예측을 수행할 수 있었으며, 실험 결과 공간 영역에서의 움직임 예측 알고리즘에 비해 낮은 비트량과 높은 PSNR(peak signal-to-noise ratio)을 제공함을 확인하였다.

• Korean Journal of Mathematics
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• 제26권3호
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• pp.387-403
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• 2018

Shifting, scaling and modulation proprerties for the convolution product of the Fourier-Feynman transform of functionals in a generalized Fresnel class ${\mathcal{F}}_{A1,A2}$ are given. These properties help us to obtain convolution product of new functionals from the convolution product of old functionals which we know their convolution product.

• Korean Journal of Mathematics
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• 제25권3호
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• pp.335-347
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• 2017

Time shifting and frequency shifting proprerties for the Fourier-Feynman transform of functionals in a generalized Fresnel class ${\mathcal{F}}_{A_1,A_2}$ are given. We discuss scaling and modulation proprerties for the Fourier-Feynman transform. These properties help us to obtain Fourier-Feynman transforms of new functionals from the Fourier-Feynman transforms of old functionals which we know their Fourier-Feynman transforms.

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 동계학술발표회 논문집
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• pp.335-336
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• 2006

We propose a method of encryption and decryption of binary data using 2-step phase-shifting digital interferometry. This technique reduces the number of interferograms in the phase-shifting interferometry. The binary data has been expressed with random code and random phase. We remove the dc-term of the phase-shifting digital interferogram to restore the original binary data. Simulation results shows that the proposed technique can be used for binary data encryption and decryption.