• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1009-1012
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• 2008

The fiber dispersion performance in fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the fiber dispersion performance in the composite PVA-ECC(Polyvinyl alcohol-Engineered Cementitious Composite) is extremely challenging because of the low contrast of PVA fibers with the cement-based matrix. In the present work, an enhanced fiber detection technique is developed and demonstrated. Using a fluorescence technique on the PVA-ECC, PVA fibers are observed as green dots in the cross-section of the composite. After capturing the fluorescence image with a Charged Couple Device(CCD) camera through a microscope. The fibers are more accurately detected by employing a series of process based on a categorization, watershed segmentation, and morphological reconstruction.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.148-156
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• 2007

The fiber dispersion in fiber-reinferced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the fiber dispersion in the composite PVA-ECC (polyvinyl alcohol-engineered cementitious composite) is extremely challenging because of the low contrast of PVA fibers with the cement-based matrix. In the present work, a new evaluation method is developed and demonstrated. Using a fluorescence technique on the PVA-ECC, PVA fibers are observed as green dots in the cross-section of the composite. After capturing the fluorescence image with a charged couple device (CCD) camera through a microscope, the fiber dispersion is evaluated using an image processing technique and statistical tools. In this image processing technique, the fibers are more accurately detected by employing an enhanced algorithm developed based on a discriminant method and watershed segmentation. The influence of fiber orientation on the fiber dispersion evaluation was also investigated via shape analyses of fiber images.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.587-596
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• 2009

The fiber bridging model is the crucial factor to predict or analyze the tensile behavior of fiber reinforced cementitious composites. This paper presents the fiber bridging constitutive law considering the distribution of fiber inclined angle and the number of fibers in engineered cementitious composites. The distribution of fiber inclined angle and the number of fibers are measured and analyzed by the image processing technique. The fiber distribution are considerably different from those obtained by assuming two- or three-dimensional random distributions for the fiber inclined angle. The simulation of the uniaxial tension behavior was performed considering the distribution of fiber inclined angle and number of fibers measured by the sectional image analysis. The simulation results exhibit multiple cracking and strain hardening behavior that correspond well with test results.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.513-522
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• 2008

The fiber dispersion performance in fiber-reinforced cementitious composites is a crucial factor with respect to achieving desired mechanical performance. However, evaluation of the fiber dispersion performance in the composite PVA-ECC (Polyvinyl alcohol-Engineered Cementitious Composite) is extremely challenging because of the low contrast of PVA fibers with the cement-based matrix. In the present work, an enhanced fiber detection technique is developed and demonstrated. Using a fluorescence technique on the PVA-ECC, PVA fibers are observed as green dots in the cross-section of the composite. After capturing the fluorescence image with a Charged Couple Device (CCD) camera through a microscope. The fibers are more accurately detected by employing a series of process based on a categorization, watershed segmentation, and morphological reconstruction.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.296-300
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• 1998

섬유산업내의 정보를 수집하고 체계화하여 경쟁력이 있는 제품을 생산해 내는데 있어서 데이타 베이스를 제공하는 일은 중요하다. 그 일부로서 제품의 경쟁력과 부가가치를 향상시킬수 있는 상표가 가지는 영향은 매우 크다고 볼 수 있다. 따라서 국내외 많은 선행 연구자들은 상표의 인지도, 상표 이미지와 상표 포지셔닝에 관하여 연구하였으며 의복의 구매행동과의 관련성을 규명하고자 하였다.[1,3,5](중략)

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2003.11a
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• pp.1381-1385
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• 2003

본 연구에서는 이미지 분석기법으로부터 측정된 표면섬유과 가와바타 측정법에 의해 측정된 직물의 표면특성과 주관적 거칠기, 따뜻함간의 관계를 고찰하였다. 시료로는 춘추용 수트직물로 사용되는 평직과 능직의 소모직물 32종을 사용하였다. 표면섬유의 분석을 위해서 이미지 분석장치로부터 촬영된 직물 표면 이미지로부터 단위길이의 직물안에 들어가는 표면섬유의 총길이(Fiber Aggregate Length)가 측정되었다. 직물의 주관적 평가를 위해 일관성 테스트와 평가능력 향상 훈련을 마친 20명 패널을 대상으로 기준직물을 제시한 9 의미미분척도를 사용하여 직물의 거칠기와 따뜻함에 대해 평가하였다. 직물의 표면섬유와 주관적인 거칠기, 따뜻함간의 상관성이 분석되었고, 직물의 표면 특성, 표면섬유로부터 직물의 감각을 판별하는 판별식을 도출하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.235-238
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• 2009

최근 생활수준의 향상으로 의복의 기능성이 중시되면서, 건강, 감성, 쾌적 등에 대한 욕구를 충족시킬 수 있는 건강 소재 개발에 대한 연구와 니트에 관한 선호도 및 감성연구는 활발히 진행되고 있다. 그러나 현재까지 건강 니트 소재의 감각 및 감성이미지에 관한 연구는 부족한 실정이다. 본 연구는 키토산 섬유와 서스 섬유의 니트 소재를 편성한 다음 최종 소비자의 감각과 감성이미지에 미치는 영향을 연구하여 실제 건강 니트 소재를 기획하는데 필요한 정보를 제시하고자 한다. 본 연구에서 키토산 섬유와 서스 섬유를 회색계열로 변화를 주어 10 게이지의 컴퓨터 자동 횡편기로 5 종의 평편 시료를 편성하였고 20 대 남녀 대학생 69 명을 대상으로 5 종의 시료($20\;cm{\times}15\;cm$)를 랜덤한 순서로 제시하여 눈으로 시료를 보고 직접 만지면서 평가하도록 하였으며, 감각 18 개와 감성 22 개, 선호도 3 개의 총 43 개 형용사로 이루어진 7 점 척도를 사용하였다. 건강 니트 소재의 감각 및 감성 이미지를 요인 분석한 결과, 감각요인은 '부피감', '요철감', '신축감', '현시감', 변형감'의 5 가지 요인, 감성요인은 '온유감', '안정감', '고급감', '활동감'의 4 가지 요인으로 분류되었다. 색 속성 중 명도 수준별 감각요인 및 감성요인 중 '요철감'과 '안정감'의 매우 유의한 차이가 나타났다. 고명도, 저명도 수준은 울퉁불퉁하고 오톨도톨하지만 안정적이고 깨끗한 이미지로 느끼는 것으로 나타났고 중간 명도수준은 '요철감'과 '안정감'이 감소되었다. 차콜색의 키토산 100%와 연회씩의 서스 100%의 경우 울퉁불퉁하고 오톨도톨하지만 안정적이고 깨끗한 이미지로 느끼는 것으로 나타났고, 차콜색 키토산섬유와 연회색 서스섬유를 혼방하여 편성한 경우 '요철감'과 '안정감'이 감소되었다.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.731-739
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• 2008

To evaluate the fiber orientation characteristics and estimate its effect on the flexural strength of steel fiber reinforced ultra high strength concrete with directions of concrete placing, we developed an image processing technique and carried out the flexural test to quantify the effect of fiber orientation characteristics on the flexural strength as well. The image processing technique developed in this study could evaluate quantitatively the fiber orientation property by the use of dispersion coefficient, the number of fibers in a unit area, and fiber orientation. It was also found that the fiber orientation characteristics were dependent on the direction of concrete placing. Fiber orientation characteristic was revealed to strongly affect the ultimate flexural strength, while hardly affecting the first cracking strength. Theoretical model for flexural strength was applied to compare with test results, which exhibited a good agreement.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.5
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• pp.323-330
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• 2023

The development of an analysis model that reflects the microstructure characteristics of polyvinyl alcohol (PVA) fiber-reinforced cementitious composites, which have a highly complex microstructure, enables synergy between efficient material design and real experiments. PVA fiber orientations are an important factor that influences the mechanical behavior of PVA fiber-reinforced cementitious composites. Owing to the difficulty in distinguishing the gray level value obtained from micro-CT images of PVA fibers from adjacent phases, fiber segmentation is time-consuming work. In this study, a micro-CT test with a voxel size of 0.65 ㎛³ was performed to investigate the three-dimensional distribution of fibers. To segment the fibers and generate training data, histogram, morphology, and gradient-based phase-segmentation methods were used. A U-net model was proposed to segment fibers from micro-CT images of PVA fiber-reinforced cementitious composites. Data augmentation was applied to increase the accuracy of the training, using a total of 1024 images as training data. The performance of the model was evaluated using accuracy, precision, recall, and F1 score. The trained model achieved a high fiber segmentation performance and efficiency, and the approach can be applied to other specimens as well.

• Proceedings of the Korean Fiber Society Conference
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• 1999.10a
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• pp.179-182
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• 1999