• 방송공학회논문지
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• 제11권4호
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• pp.386-395
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• 2006

다시점 영상 부호화 기술은 다시점 카메라로부터 취득된 다수의 영상을 부호화하는 기술로 매우 효율적인 압축 기술이 요구된다. 이를 위해 시점 간 예측 기술을 사용하고 있으나 예측 기법의 개선만으로는 전반적인 압축 성능 향상에는 한계를 보인다. 따라서 본 논문에서는 역양자화기의 성능 개선을 통해 다시점 영상 부호화의 압축 효율을 보다 향상 시키고자 한다. 다시점 영상 부호화는 기본적으로 H.264/AVC를 기반으로 구현되어 있으므로 H.264/AVC의 양자화/역양자화 기법을 그대로 사용하고 있다. 기존 양자화/역양자화 기법의 문제점은 부호화해야 하는 오류 신호들의 확률 분포가 라플라시안 분포를 갖는다는 가정 하에 양자화기와 역양자화기가 설계되어 있어 입력되는 신호가 라플라시안 분포를 따르지 않을 경우 성능이 떨어진다. 이와 같은 오류 신호의 실제 확률 분호와 양자화/역양자화기의 확률 분포 불일치 문제로 인한 압축 효율 저하 문제를 해결하기 위해 본 논문에서는 양자화 계수 분포 기반의 효율적 역양자화 기법을 제안하다. 추가적인 정보의 전송 없이 복호기에 전송된 양자화 계수들을 이용하여 원본 오류 신호의 확률 분포를 예측하고 이를 바탕으로 보다 정확한 역양자화 값을 찾아내어 압축 성능을 개선한다. 다양한 실험 결과 제안하는 알고리듬은 기존 알고리듬에 비해 높은 비트율에서 최대 1.5 dB에서 최소 0.6 dB의 성능향상을 보인다.

• 한국유체기계학회 논문집
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• 제11권6호
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• pp.18-23
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• 2008

In this paper, effects of inlet shape on the performance of a submerged cargo pump were numerically studied using a commercial CFD code ANSYS-CFX. The inlet shape, especially the gap between pump and suction well, is an important parameter in a point of view of performances of submerged cargo pump due to its effects on the residual and also hydraulic performance of the pump, respectively. To investigate the optimized gap, the overall performance degradations were calculated with the gap. In addition to that, the flow field through the gap was investigated to explain the effect of velocity non-uniformity on the performance of the pump impeller.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1582-1590
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• 2011

An analysis of the railroad industry for R&D investments has been insufficient whereas there are lots of analysis of accumulation of technology, economic performances and ripple effects for macroscopic view and other industry of R&D investments. This study decided intellectual rights, patent, and paper as common indicators of scientific and technological performances for setting up performance targets through surveying and analysis of preceding study and verified a appropriateness of scientific and technological performances for railroad R&D 11 projects which were successfully finished. Preceding study has been set up performance targets by research investments as input, but this study made a performance target by model through a cross-sectional and residual analysis of performances of railroad R&D 11 Projects in applying research investments, capital investments, inner labor cost and inner labor cost per man and research time as inputs, and verified a validity and a empirical analysis through analysis of other project.

• 한국화재소방학회논문지
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• 제1권1호
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• pp.19-26
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• 1987

In this study, fire resistance of steel fiber reinforced concrete was investigated Cylindrical and prismatic specimens made of Ordinary Portland Cement plain concrete and steel fiber reinforced concrete were exposed to heating in accordance with a standard time-temperature curve as specified in KS·F22 57, method of fire resistance test for structural parts of buildings, the period of heating was 1 hour and 2 hours. After the fire resistance test, mechanical properties of specimens such as compressive and bending strength, stress-strain curve, static and dynamic modulus of elasticity and bending toughness were investigated. Also the cracks and spallings of the specimens were observed. From the test results, it was confirmed that steel fiber reinforced concrete has a excellent fire resistance than plain concrete in the view of higher residual strength of concrete and smaller crackings because of steel fibers in concrete.

• Communications for Statistical Applications and Methods
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• 제18권4호
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• pp.485-493
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• 2011

The proportional likelihood ratio order is an extension of the likelihood ratio order for the non-negative absolutely continuous random variables. In addition, the Lindley distribution has been over looked as a mixture of two exponential distributions due to the popularity of the exponential distribution. In this paper, we first recalled the above concepts and then obtained various properties of the Lindley distribution due to the proportional likelihood ratio order. These results are more general than the likelihood ratio ordering aspects related to this distribution. Finally, we discussed the proportional likelihood ratio ordering in view of the weighted version of the Lindley distribution.

• 한국생산제조학회지
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• 제19권5호
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• pp.616-621
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• 2010

New type of the base material of the light-emitting diode requires copper wafer in view of heat and electrical conductance. Therefore, polishing process of the substrate level is needed to get a nanometer level of surface roughness as compared with pattern structure of nano-size in the semiconductor industry. In this paper, a series of lapping and polishing technique is shown for the rough and deflected copper substrate of thickness 3mm. Lapping by sand papers tried air cooling method. And two steps of polishing used the diamond abrasives and the $Al_2O_3$ slurry of size 100mm considering the residual scratch. White-light interferometer proved successfully a mirror-like surface roughness of Ra 6nm on the area of $0.56mm{\times}0.42mm$.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.752-756
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• 2002

Variable weld bead penetrations related to the base metal chemistry of stainless steels in GTA welding have been under constant investigations due to their industrial implications. It has been proposed that among other elements, the sulfur content of steels determines the weld pool geometry, particularly its penetration. It is suggested that the surface tension temperature gradient of steels becomes positive with appropriate dosing in sulfur and results in inward melt flow, propitious for deeper welds. However, the chemistry of industrial steels is complex due to the presence of multiple minor elements either deliberately added or remnant impurity traces. With this in view, investigations on 41 austenitic and nine martensitic stainless steels were carried to see if there existed any possible relation between the weld profile and some of the designated elements. The results suggest no direct correlation between sulfur or any other major or trace element and weld penetration. At first glance the results are contradictory to what is often asserted.

• Journal of Welding and Joining
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• 제18권3호
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• pp.68-75
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• 2000

The incomplete penetration(IP) discontinuity in butt joint weld, which is detected during safety analysis of the steel bridge by nondestructive evaluation(NDE) method, is classified as unacceptable defect according to the NDE codes and standards. In fact, there are a little allowance in butt joint weld in the view point of design criterion, and also detected IP discontinuity should be classified and evaluated for the fatigue strength and residual life estimation. In this study, we performed fatigue test to evaluate the fatigue strength of high strength steel(SWS490A) containing IP discontinuities in various size, the results compared and classified according to the bridge construction standard specification which published by korea administration of construction and traffic. Experimental results could be used to evaluate and estimate the IP discontinuities considering different stress range in butt joint bridge weld during periodic safety inspection.

• 한국통신학회논문지
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• 제27권3A호
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• pp.249-257
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• 2002

본 논문에서는 스테레오/다시점 영상을 효율적으로 압축할 수 있는 차 영상 부호화 방법을 제안한다. 예측된 영상과 원 영상의 차이 정보를 보다 효율적으로 전송하기 위하여 DCT를 기반으로 차 영상 부호화를 하게 되는데 DCT 계수들의 방향성을 이용하여 양자화 및 스캔 방법을 각 블록의 특성에 따라 다르게 적용하였다. 특히 다시점 영상의 부호화는 첫 번째 시점 영상을 기준 영상으로 정하여 나머지 시점 영상을 기준 영상으로부터 변이를 추정하여 복원하는 방식과 다시점 영상 중 가려진 영역의 비율을 고려하여 가려진 영역이 상대적으로 제일 적은 영상을 기준 영상으로 설정하여 나머지 영상을 변이 추정하여 복원하는 방법으로 나누어 실험하였다. 실험 결과 모든 압축률에 대하여 제안 방식이 기존의 차 영상 부호화 방법보다 우수함을 확인하였고, 가려진 영역의 상대적인 비율을 고려하여 다시점 영상을 부호화한 제안 방식이 기존의 방식 및 첫 번째 시점을 기준 영상으로 설정하여 부호화한 제안 방식보다 우수함을 확인하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.62-74
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• 2001

Present paper describes the principles of PIV measurement approaching from the analytical view, which enables to explain the general form of principles covering all the PIV measurement, and that gives theoretical basis for its higher measurement performances. The explanation of the measurement principles started from the definition of governing equation in differential form as same as the gradient method, and the integral along the particle path line was executed to show the principle of the correlation method with same basis. The integral processes clearly shows the analytical reason why the correlation peak gives the terminal point of path line, and how the effects of deformation and rotation of fluid appears in the correlation map. These results have no differences from our experiences and understandings of the conventional PIV measurement definition in final form. However, the analytical approach enable to understand those facts a priori, and it makes easy to achieve the innovative higher performances of measurement. Analytical explanation clearly shows the behavior of the residual errors caused by the fluid motion, and it enables to analyze the measurement uncertainty theoretically.