• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2555-2575
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• 2017

This paper presents a dual exposure fusion method for image enhancement. Images taken with a short exposure time usually contain a sharp structure, but they are dark and are prone to be contaminated by noise. In contrast, long-exposure images are bright and noise-free, but usually suffer from blurring artifacts. Thus, we fuse the dual exposures to generate an enhanced image that is well-exposed, noise-free, and blur-free. To this end, we present a new scale-space patch-match method to find correspondences between the short and long exposures so that proper color components can be combined within a proposed dual non-local (DNL) means framework. We also present a residual filtering method that eliminates the structure component in the estimated noise image in order to obtain a sharper and further enhanced image. To this end, the entropy is utilized to determine the proper size of the filtering window. Experimental results show that our method generates ghost-free, noise-free, and blur-free enhanced images from the short and long exposure pairs for various dynamic scenes.

• 한국농공학회논문집
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• 제46권3호
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• pp.65-72
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• 2004

Modern underground and tunnel works that the wet type shotcrete is getting widely designed and applied in a large scale project. Further to its applications, the needs of improving the performance of the shotcrete, such as new and developed additives and accelerators fur increasing the performance of shotcrete, become the most important issue in the field. The main objective of this study evaluated to performance of steel fiber reinforced shotcrete using alkali free based accelerator for the durability and high quality of shotcrete. The major test variables are accelerator type and its dosage. One type silicate based accelerator and one type aluminate based accelerator and one type alkali free based accelerator were used. The dosage of accelerators is determined by the manufactures and laboratory test condition. Compressive strength test results showed that the dosage of silicate and aluminate based accelerators caused reduction of mechanical properties of shotcrete. Compressive strength of alkali free based accelerator is more stable than of silicate and aluminate based accelerators. Also, according to the compressive strength and flexural test results, it was found that steel fiber reinforced shotcrete used alkali free based accelerator could attain significant improvement in the mechanical and flexural performance.

• Wind and Structures
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• 제2권4호
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• pp.253-266
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• 1999

This paper presents the effects of free-stream turbulence on streamwise surface pressure fluctuations on two-dimensional rectangular cylinders. Particular attention is given to possible effects of turbulence integral scale on fluctuation and peak pressures. The mean, standard deviation, peak pressure coefficients, spectra and cross-correlation of fluctuating pressures were measured to investigate the nature of the separation and reattachment phenomenon in turbulent flows over a wide range of turbulence intensity and integral scale.

• Journal of the Korean Statistical Society
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• 제9권2호
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• pp.181-193
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• 1980

A class of nonparametric estimators of the ratio of scale parameters is proposed. The estimators are based on the distribution-free rank-like test suggested by Fligner and Killeen (1976). An explicit form of the estimator is the median of the ratios of absolute deviations from the combined sample median. A small-sample Monte Carlo study shows that the proposed estimator is more efficient than the Bhattacharyya (1977) estimator. The proposed estimator is is reasonably insensitive to small failures in the assumption of equal medians. A modified estimator is also considered when the meidans are unequal.

• Wind and Structures
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• 제6권6호
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• pp.419-436
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• 2003

Large-eddy simulations of the flow around a circular cylinder at a Reynolds number, based on cylinder diameter and free-stream velocity, $Re_D=2{\times}10^4$ are presented. Three different dynamic subgrid-scale models are used, viz. the dynamic eddy-viscosity model and two different mixed two-parameter models. The sensitivity to grid refinement in the spanwise and radial directions is systematically investigated. For the highest resolution considered, the effects of subgrid-scale modeling are also discussed in detail. In particular, it is shown that SGS modeling has a significant influence on the low-frequency modulations of the aerodynamics loads, which are related to significant changes in the near wake structure.

• 천문학회지
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• 제34권4호
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• pp.181-190
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• 2001

The advent of robust, reliable and accurate higher order Godunov schemes for many of the systems of equations of interest in computational astrophysics has made it important to understand how to solve them in multi-scale fashion. This is so because the physics associated with astrophysical phenomena evolves in multi-scale fashion and we wish to arrive at a multi-scale simulational capability to represent the physics. Because astrophysical systems have magnetic fields, multi-scale magnetohydrodynamics (MHD) is of especial interest. In this paper we first discuss general issues in adaptive mesh refinement (AMR), We then focus on the important issues in carrying out divergence-free AMR-MHD and catalogue the progress we have made in that area. We show that AMR methods lend themselves to easy parallelization. We then discuss applications of the RIEMANN framework for AMR-MHD to problems in computational astophysics.

• KSBB Journal
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• 제21권4호
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• pp.306-311
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• 2006

세포의 보존은 세포의 배양에 있어서 필수 불가결한 요건으로서 세포주의 다양한 특성에 따라 적합한 방법이 확립되어야 한다. 본 연구에서는 산업용 세포주인 CHO 세포의 단기간 저온보존 기술의 확립을 목표로 진행되었으며 다양한 조건을 통해 가장 안정적인 저온보존 방법을 수립하였다. 저온보존 방법에 있어서 가장 중요한 요인은 온도로서 $4^{\circ}C$ 저온보존이 세포 보존에 필수적인 조건으로 나타났으며 $20^{\circ}C$ 실온보존에서는 세포의 급격한 사멸이 관찰되었다. 보존형태는 용기를 눕힌 상태로 서서히 회전시켜 현탁 보존하는 방법이 용기를 세우거나 눕혀 보관하는 방법에 비해 높은 생존율을 나타내었다. 또한 저온보존 시 새로운 배지로 교환한 후 보존하는 방법이 배양에 사용된 배지를 그대로 사용한 보존 방법보다 세포의 성장 회복율에서 우수한 것으로 나타났다. 하지만 $4^{\circ}C$에서 rolling을 통한 현탁 보존을 할 경우에는 배지의 교환 없이도 안정적으로 세포보존이 가능한 것으로 나타났다. 저온보존에 가장 적합한 세포의 농도는 실험결과 $1.0{\times}10^6{\sim}5.0{\times}10^6cells/m{\ell}$ 범위로 나타났으며 혐기적인 상태로 보존하는 것이 공기가 존재하는 보존방법 보다 비교적 우수한 보존 결과를 나타내었다. 이상의 결과를 바탕으로 무혈청 배지의 저온보존액으로서의 안정성과 첨가물에 의한 보존효율의 향상을 평가하였다. 실험결과 저온보존 후 10일간은 높은 세포 생존율과 함께 정상적인 세포 성장 회복을 보이는 것으로 나타났으며 ${\alpha}$-tocopherol과 retinoic acid를 첨가한 저온보존액의 경우에는 더욱 우수한 세포 생존율을 보임을 확인하였다. 마지막으로 이렇게 확립된 방법을 이용하여 1 L 용량의 저온보존 실험을 수행한 결과, 앞선 실험에서와 유사한 경향의 세포 보존 능력을 확인할 수 있었다. 이러한 결과를 종합해 볼 때 산업용 세포주로 널리 사용되는 CHO 세포의 저온보존은 본 연구에서 확립된 방법을 통해 단기간 동안 안정적으로 수행될 수 있을 것으로 사료되며 대용량 저온보존의 적용 가능성도 확인하였다. 대용량 배양에서의 단기간 보존기술에 대한 연구가 앞으로 더 많이 수행된다면 실제 배양 공정에서도 저온보존 기술의 적용이 가능할 것으로 판단된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1998년도 학술발표회 논문집
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• pp.3-3
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• 1998

In this pressentation it is argued that the heterogeneity of a hydrologic attribute which may seem to be nonstationary at one scale, may become stationary at a larger scale. The fundamental reason for transformation from nonstationarity to stationarity whith the increase in scale is the phenomenon of coarse-graining of the hydrologic processes with increasing scale. Due to the phenomenon of aliasing, a particular scale hydrologic process heterogeneity which is observed as a nonstationary process at that scale, may be observed as a stationary process at a higher(larger) scale whose size is bigger than the stationary extent of the lower scale heterogeneity. As one goes through a hierarchical sequence of larger and larger scales for observations, one would eliminate nonstationarities which emerge at some lower scales at the expense of losing information on the high frequency fluctuations of the lower scale heterogeneities which will no longer be observed at the larger sampling scales. We call this phenimenon as the "coarse-graining in hydrologic observations". In this presentation, it is also argued that by the coarse-graining of hydrologic processes due to the averaging and aliasing operations at increasing scales, the conservation laws corresponging to these scales may still be quite parsimonious, and need not be more complicated as the scales get larger. It is shown that shen a higher(larger) scale process is formed by averaging a lower(smaller) scale process in time or space, the high frequency components of the lower scale process will be eliminated by the averaging operation. Thereby, the resuliiting average hydrologic dynamics, free from the effects of the high frequency components of the lower scale process, can still be quite simple in form. This is demonstrated by means of some recent upscaling work on the solute teansport conservation equation for hetergeneous aquifers. By means of this solute transport example, it is also shown that for the ensemble average form of a hydrologic conservation equation to be equivalent to its volume-average form at any scale, the parameter functions of that conservation equation at the immediately lower scale must be ergodic.

• 한국콘텐츠학회논문지
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• 제16권10호
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• pp.711-718
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• 2016

본 연구는 이중과제 훈련이 만성기 뇌졸중 환자들의 균형 능력 및 상지기능에 미치는 효과를 알아보고자 실시되었다. 경상북도 A병원에 내원한 뇌졸중 17명을 대상으로 하였으며, 이중과제 훈련은 전 후 평가를 제외한 총 4주 동안 주 5회 30분씩 실시하였다. 평가도구는 버그균형 척도(Berg Balance Scale), BTS FreeEMG 300(BTS FreeEMG 300, BTS, Italy)이 사용되었다. 연구 결과 이중과제 훈련 실시 전에 비하여 실시 후 만성기 뇌졸중 환자들의 BBS 점수에서 유의미한 변화가 나타났고(p<.05), CCR값에서도 어깨 및 팔꿈치 관절 동작 모두에서 음의 값이 나타나 긍정적인 변화가 있었다. 본 연구의 결과로 볼 때 이중과제 훈련이 만성기 뇌졸중 환자들의 균형 능력 및 상지기능 향상에 긍정적인 효과의 가능성을 확인할 수 있었다.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.82-88
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• 2014

Using low outdoor temperature, free cooling system is used in a data center or industrial air-conditioning for energy saving. Because use of IT equipment has increased in some office building recently, there is a growing trend towards using free cooing system. Free cooling system performance is influenced by outdoor temperature. Therefore the performance is different with regions. In this study, performance characteristic of free cooling system is analysed and energy reduction is compared with some regions. Selected regions are 4 cities; including Ulsan analyzed in preceding research, Seoul, ChunCheon and Daejeon. The Aspentech software HYSYS 8.0v was used to conduct the analysis of free cooling system based on temperature per hour of 4 cities in 2013, respectively. The main result is following as. Free cooing system in this study has energy saving effect when outdoor temperature below $7^{\circ}C$. Becuase temperature of Chuncheon is relatively low, using free cooling system can conserve most air-conditioning energy. Energy reduction amount of Seoul is 11%, Chuncheon is 17.5%, Deajeon is 15%, Ulsan is 14%. In case of large scale of air-conditioning, it is reasonable to use free cooling system although the system is used in Seoul.