• 대한원격탐사학회지
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• 제28권3호
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• pp.287-296
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• 2012

Although low spatial resolution satellite images like MODIS and GOCI can be important to observe land surface, it is often difficult to visually interpret the imagery because of the low contrast by prevailing cloud covers. We proposed a simple and adaptive stretching algorithm to enhance image contrast over land areas in cloudy images. The proposed method is basically a linear algorithm that stretches only non-cloud pixels. The adaptive linear stretch method uses two values: the low limit (L) from image statistics and upper limit (U) from low boundary value of cloud pixels. The cloud pixel value was automatically determined by pre-developed empirical function for each spectral band. We used MODIS and GOCI images having various types of cloud distributions and coverage. The adaptive contrast stretching method was evaluated by both visual interpretation and statistical distribution of displayed brightness values.

• 전기전자학회논문지
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• 제22권3호
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• pp.585-589
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• 2018

Consumer demand for high quality image/video services led to growing trend in image quality enhancement study. Therefore, recent years was a period of substantial progress in this research field. Through careful observation of the image quality after processing by image enhancement algorithms, we perceived that the dark region in the image usually suffered loss of contrast to a certain extent. In this paper, the low-light stretch preprocessing algorithm is, hence, proposed to resolve the aforementioned issue. The proposed approach is evaluated qualitatively and quantitatively against the well-known histogram equalization and Photoshop curve adjustment. The evaluation results validate the efficiency and superiority of the low-light stretch over the benchmarking methods. In addition, we also propose the 255MHz-capable hardware implementation to ease the process of incorporating low-light stretch into real-time imaging systems, such as aerial surveillance and monitoring with drones and driving aiding systems.

• 한국멀티미디어학회논문지
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• 제6권6호
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• pp.977-984
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• 2003

본 논문에서는 파노라믹 적외선 영상에서의 영상 향상 기법을 제안하였다. 제안한 기법에서는 먼저 파노라믹 적외선 영상을 작은 부영상으로 나누고, 각 부영상의 통계적 특성을 이용하여 각 부영상에 대하여 대조 확장을 행한다. 그러나 이때 통계적 특성이 다른 인접하는 부영상의 경계 영역에서는 블럭화 현상이 나타난다. 이러한 블럭화 현상을 제거하기 위하여 제안한 기법에서는 수평적으로 인접하는 부영상의 통계적 특성을 이용하여 부영상의 경계영역에 대하여 대조 확장을 행한다. 실험을 통하여 제안한 기법이 효율적으로 시각적인 화질을 개선하였음을 확인하였다.

• 한국생활과학회지
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• 제14권6호
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• pp.995-1006
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• 2005

The purpose of this study was to investigate the wearing sensation and satisfaction of high school girls' winter uniform jackets according to the fabrics and the shapes. The fabrics were divided into four parts of stretch and non-stretch woven fabrics. The shapes were divided into two parts of tight and general types. The results were as followings: 1. In the aspect of the appearance evaluation for the uniform jackets, silhouette and length item showed significant differences in fabric and shape. The non-stretch woven fabric and tight type was more satisfying than the stretch fabric and general type because its silhouette and length were shorter and fitter than the stretch one and general type. The jackets of non-stretch woven fabric of tight type were evaluated as the thinnest in the silhouette and were evaluated as the shortest in the length. Conversely, the jackets of stretch woven fabric of general type were evaluated as the thickest and longest. 2. As for the wearing sensation of school uniform jacket, all test items showed significant differences in fabric and shape. The stretch fabric and general type was more satisfying than the non-stretch woven fabric and tight type because the jacket of stretch fabric and general type was felt more comfortable in activities, and wearing. Accordingly, the appearance evaluation for uniforms' jacket is in sharp contrast with that of wearing sensation.

• 한국운동역학회지
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• 제25권2호
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• pp.149-155
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• 2015

Purpose : Recently, many researchers and golf coachers demonstrated that X-factor and X-factor stretch had a co-relationship with driving distance. However, its relationship is still controversial and ambiguous. Thus, the aim of this study was to examine the relationship among X-factor, X-factor stretch and swing-related factors, including driving distance in elite golfers. Method : Seventeen male elite golfers (handicap: ${\leq}4$) with no history of musculo-skeletal injuries participated in the study. Thirty spherical retro-reflective markers were placed on including the middle point of PSIS, the right/left ASIS, the right/left lateral acromion of the scapula, driver head and shaft grip. All motion capture data was collected at 100Hz using 6 infrared cameras. Carry distance, club speed, ball speed, smash factor, launch angle, and spin rate were collected from radar-based device, TrackMan. Results : Pearson's correlation coefficient method was used to find the correlations among X-factor, X-factor stretch and swing-related factors. Positive correlations between driving distance and other swing-related factors which include club speed(r=.798, p<.001), and ball speed(r=.948, p<.001) were observed. In contrast to the swing-related factors, X-factor and X-factor stretch had no relationship to driving distance. Conclusion : These results indicate that X-factor and X-factor stretch are not key regulators in driving distance.

• 대한의생명과학회지
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• 제11권1호
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• pp.23-29
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• 2005

Molecular imaging with targeted contrast agents enables tissues to be distinguished by detecting specific cell-surface receptors. In the present study, a ligand-targeted acoustic nanoparticle system is used to identify angioplasty-induced expression of tissue factor by smooth muscle cell within carotid arteries. Pig carotid arteries were overstretched with balloon catheters, treated with tissue factor-targeted or a control nanoparticle system, and imaged with intravascular ultrasound before and after treatment. Tissue factor-targeted emulsion bound and increased the echogenicity and gray-scale levels of overstretched smooth muscle cell within the tunica media, versus no change in contralateral control arteries. Expression of stretch-induced tissue factor in carotid artery media was confirmed by immunohistochemistry. The potential for abnormal thrombogenicity of balloon-injured arteries, as reflected by smooth muscle expression of tissue factor, was imaged using a novel, targeted, nanoparticulate ultrasonic contrast agent.

• 대한기계학회논문집B
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• 제21권1호
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• pp.125-131
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• 1997

The extinction of premixed flames under the influence of stretch is studied numerically. A wide range of fuel (hydrogen, ethylene, acetylene, methane, propane and methanol) and air mixtures are established in an opposed jet and their flame properties such as flame speed, flame thickness, thermal diffusivity, and stretch rate at extinction are computed. Computations are made using several chemical kinetic mechanism (Smooke, Kee et al. and Peters). The major result is that, in contrast to the various previous claims of extinction Karlovitz number varying over three orders of magnitude, it is found to be constant around two for all of the mixtures tested. That is, premixed flames are extinguished when the physical flow time decreases (due to increased stretch rate) to the point where it approximately equals the chemical reaction time. Here the relevant chemical reaction time is not the one computed using the one-dimensional flame properties as originally suggested in the formulation of Karlovitz number, but rather it is the one obtained using the stretched flame properties which fully reflect the effect of straining on the flame structure.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1719-1722
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• 2003

Image enhancement를 하기 위한 영상처리 알고리즘 중의 하나인 contrast enhancement 알고리즘은 화면의 flickering 과 같은 부작용과 조절 가능한 contrast enhancement rate 에 대한 구현의 어려움 등으로 실제 TV와 같은 동영상에 적용하기에 어려움이 있었다. 본 논문에서는 Bin Underflow Bin Overflow(BUBO)를 이용하여 동영상에 적용할 경우에도 flickering 등의 부작용이 생기지 않으며 contrast enhancement rate 을 조절할 수 있는 효율적인 알고리즘을 제안한다. 또한 이와 관련하여 영상의 휘도 레벨에 있어서 어두운 영역의 계조와 밝은 영역의 계조를 향상시킬 수 있는 black/white level stretch 알고리즘과 전체 화면의 출력 휘도 레벨에 대한 dynamic range를 유지하면서 brightness를 조절할 수 있는 알고리즘을 제안한다.

• 생태와환경
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• 제40권2호
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• pp.273-284
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• 2007

동물플랑크톤의 공간적 시간적 동태 변화에 대해서 섬진강 중하 류(하구언 댐 무)및 영산강 중 하류(하구언 댐 유)약 100 km구획 내에서 2004년 11월부터 2006년 8월까지 월 간격으로 조사하였다. 두 수계 내 동물플랑크톤 생체량의 공간적 변이는 뚜렷하였다. 영산강 조사 구획 내 총 동물플랑크톤 밀도의 종적 변이는 뚜렷하였다. 강 하류 지역의 하구언 댐으로 향할수록 총 동물플랑크톤 밀도가 증가하였다. 이에 반해 섬진강의 조사 구획 내 총 동물플랑크톤 밀도 변이는 통계적으로 유의하지 않았다. 영산강 구획 내 평균 총 동물플랑크톤 밀도는(평균범위: $199{\sim}817$ 개체수 $L^{-1}$), 3 조사지점, n=20) 섬진강 구획 내 평균 총 동물플랑크톤 밀도(평균범위: $4{\sim}60$개체수 $L^{-1}$, 4 조사지점, n=20)보다 약 $4{\sim}60$ 배 정도 높았다. 영산강 수계(총 동물플랑크톤 밀도의 86% 이상)에서 윤충류의 상대 풍부도는 섬진강 수계에 비해 현저히 높았다. 두 수역에서 우점 한 종은 Polyarthra spp., Brachionus spp., Colurella spp., 및 Keratella spp. 였다. 섬진강 구획 내에서의 요각류의 탄소 생체량은 강 하류로 향할수록 증가하였다(총 동물플랑크톤 탄소 생체량의 40% 이상). 식물플랑크톤에 대한 총 동물플랑크톤 섭식률의 평균 범위는 영산강 구획 내에서는 $21.2{\sim}92.6mL\;L^{-1}\;D^{-1}$이며, 섬진강 구획 내에서는 $2.1{\sim}2.6mL\;L^{-1}\;D^{-1}$의 변동 범위를 보였다. 동물플랑크톤의 섭식률을 고려 해 볼 때, 영산강 구획 내에서 동물플랑크톤에 의한 플랑크톤 먹이환내에서의 역할의 중요성이 섬진강 구획 내에서 보다 상대적으로 높을 것으로 사료된다.

• 한국염색가공학회지
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• 제22권2호
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• pp.173-179
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• 2010

In this study, we determine the stretch and shrinkage properties of conjugated yarns. The shrinkage(%) and elasticity(%) were determined by applying twist conditions of 0, 350, 800, 1000, 1200, 1400, 1600, 2000 T/M (twisting per meter). It is found that the shrinkage(%) and elasticity(%) gradually decreased with increasing T/M. Especially the elasticity(%) dramatically decreased over 1400 T/M condition. In contrast, it is showed that the handle and drapery properties decreased below 1000 T/M, which indicates that the optimal T/M condition could be 1000~1400. The effect of shrinkage(%) and elasticity(%) with different steam setting temperatures (60, 70, 80 and $90^{\circ}C$) was also determined. The shrinkage(%) decreased with increasing setting temperature, while the elasticity not changed. In this context, the optimal steam setting temperature could be $80^{\circ}C$ because it is not easy to weave with the yarns which was set below $80^{\circ}C$. The elasticity(%) decreased with increasing the density of warp and weft. To produce soft handle, excellent drapery and good stretch fabrics, the warp density needs to be reached by 90% of the ideal warp density. In the case of NaOH treatments to the fabrics, the elasticity(%) increased with increasing weight reduction. Therefore, this study have demonstrated that the conjugated yarns with core yarn and the SDY CD(cation dyeable spindraw yarn) as an effect yarn would be appropriate to produce excellent mixture-yarn, which displays clean appearance, good handle and excellent elasticity, The optimized conditions are as follows; 1000~1200 twist per meter, $80^{\circ}C$ steam setting temperature, 90% of ideal warp density and relaxation condition treated with 5g/l NaOH concentration.