• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1156-1161
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• 2007

Edge representing the boundary between two regions with the large briskness difference in mage includes diverse information about object. Therefore, this information has been utilized in fields such as image segmentation and object recognition. There are many kinds of edge according to duration time and the amplitude of brightness variation and edge is generally detected through the differential. Recently, in fields of image processing and computer vision, edge detection methods have been proposed to use in specific applications. Hence, in this paper the wavelet function for improved edge detection properties was proposed and detected line-edge components of images and its performance was proven through simulations.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.703-706
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• 2004

나선형 CT 혈관촬영에서 획득한 영상의 분석를 통해서 폐색전증이 의심되는 부위를 자동으로 검출하는 방법으로, 연구 대상은 20명의 환자를 대상으로 분석하였으며 CT 검사 후 방사선과 의사가 정상소견을 받은 환자 5명과 폐색전증이 있는 판독소견을 가진 15명을 대상으로 비교 분석하였다. CT 검사하는 동안에 조영제를 투입하면, 폐색전증이 발생한 부위는 조영제 양과 분포가 불균등하여 명암값이 낮게 검출된다. 검출방법으로는 전처리 작업으로 폐영역만을 분할하고, 분할된 폐영역에서 혈관을 찾기 위해 모폴로지기법를 적용하여 세선화(thinning) 작업을 진행한다. 다음 공정으로는 경계선을 찾아 local watershed를 적용하여 혈관을 검출하고, 검출된 혈관내에서 원형모델을 적용하여 모폴로지(morphology)을 통해 국소 부위의 미세한 농도변화를 인지하여 색전이 발생한 영역을 자동검출하였다. 본 논문의 자동검출시스템에서는 색전증이 있는 경우에 true positive의 발생빈도는 case 당 4.5개가 검출되었다. 정상인의 경우에도 혈류의 흐름, 혈류의 분기점, 노이즈로 인한 false positive의 빈도는 case 당 2.6개가 발생하여 전체적으로 false positive는 5.2개가 검출되었다. 본 논문은 false positive의 비율이 높게 검출되었지만 폐영역 CT 검사의 컴퓨터지원진단시스템(computer aided diagnosis)의 향후 연구과제에 방향을 제시할 수 있을 것이라 사료된다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.1
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• pp.8-15
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• 2021

Micro-LEDs can be applied to various parts of a product. However, it has disadvantages compared to general LEDs in large displays such as low efficiency, intensity, and contrast ratio, among others, owing to their short history of study. The simulations were carried out using ray-tracing software to investigate the change in light intensity and light distribution according to pattern shapes on the sapphire substrate of the flip-chip micro-LED (FC μ-LED) array. Three patterns-concave square patterns, convex square patterns, and Ag coated convex patterns-which existed on the opposite side of FC μ-LEDs (115 ㎛ × 115 ㎛) array, were applied. The intensity of FC μ-LEDs on the center of the receivers depends on the pattern depth with shape. The concave square patterns having FC μ-LEDs arrays show that decreasing intensity as the patterns depth. On the contrary, the convex square patterns having FC μ-LEDs arrays shows that increasing intensity as the patterns depth. In addition, the highest intensity shows that FC μ-LEDs having Ag-coated convex patterns on the opposite side of sapphire lead to a reduction in light crosstalk owing to the Ag film.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.631-637
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• 1999

An investigation was carried out to study the effects of aging time, storage temperature, and drying type on the physical, chemical and sensory properties of Korean rice cake. Water content and cooking properties were significantly influenced by aging time and storage temperature. However, aging time did not affect the soup turbidity. Difference in water content was noticeable by drying type. The microwave treated rice cake (MW) showed a higher water content than the other ones. The lightness (L-value) was not affected by the aging time and drying type. Rice cake storaged at 4oC showed the highest L-value. The textural properties of rice cake were influenced by the all sources of variables. There was a significant difference in hardness between microwave and hot air treated rice cake (MWH), and microwave and vacuum treated rice cake (MWV). In the sensory properties, mean intensities of all attributes except chewiness were significantly different among drying types. The MWV showed a higher acceptability than the MW and the MWH. Scanning electron photomicrographs revealed that the MWV has more porous structure. The MWV was the most desirable one as determined by the physical, chemical and sensory evaluation.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.114-123
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• 2014

Vehicle Black Box (Event Data Recorder EDR) only recognizes the general surrounding environments of load. In addition, general EDR is difficult to recognize the images of a sudden illumination change. It appears that the lens is being a severe distortion. Therefore, general EDR does not provide the clues of the circumstances of the accident. To solve this problem, we estimate the value of Normalized Luminance Descriptor(NLD) and Normalized Contrast Descriptor(NCD). Illumination change is corrected using Normalized Image Quality(NIQ). Second, we are corrected lens distortion using model of Field Of View(FOV) based on designed method of fisheye lens. As a result, we propose integration algorithm of two methods that correct distortions of images using each Gamma Correction and Lens Correction in parallel.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.161-168
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• 2008

We propose a novel bistable nematic liquid crystal cell, which has a dual-frequency liquid crystal material and pixel-isolating polymer wall formed by an anisotropic phase separation of a mixture of liquid crystals and UV-curable pre-polymers. The proposed cell has two stable states of left- and right-handed ${\pi}$-twist. The switching between the two states is achieved by using a sequential waveform of low and high frequencies. A transmissive bistable liquid crystal display is designed, which achieves high contrast ratio by using the proposed cell and optical films.

• Journal of the Korea Society of Computer and Information
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• v.14 no.11
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• pp.61-71
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• 2009

Vehicle license plate is the only way to check the registrated information of a vehicle. Many works have been devoted to the vision system of recognizing the license plate, which has been widely used to control an illegal parking. However, it is difficult to correctly segment characters on the license plate since an illumination is affected by a weather change and a neighboring obstacles. This paper proposes a robust method of segmenting the character of the license plate on irregular illumination condition. The proposed method enhance the contrast of license plate images using the Chi-Square probability density function. For segmenting characters on the license plate, binary images with the high quality are gained by applying the adaptive threshold. Preprocessing and labeling algorithm are used to eliminate noises existing during the whole segmentation process. Finally, profiling method is applied to segment characters on license plate from binary images.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.93-101
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• 1998

The present study was conducted to investigate the structural changes in rat cornes. Sixty eyes from one-day-old uneyed rats, fourty eyes from 10-weeks-old adult rats were used. With the increase of age, the epithelial layer was thickened by the addition of new successive cellular layers. Then, the new-born rat's epithelial cells formed a pentagonal shape, and the quality of decidual cells showed a high electron-density, although the boundary between cells was distinctive. The newly produced cells showed a low electron-density so that there was the distinctive difference between light and darkness. In Bowman's layer, collagen fibrils demonstrate a regularly arranged structure along with the age. In stroma's layer, the density of keratocytes was decreased and thereby progressively flattened during the development. The collagenous layer of the adult rats was more distinctive than that of the new-born rats in a form of vertical and horizontal parallel alignment running vertically and horizontally. Descemet's membrane changed its structure significantly along with the age. It changed the shape from "banded-layer" to "non-banded layer" gradually. The thickness was also increased along with the age. Regardless of developmental stages, the endothelium is usually monolayer. During the developmental process, endothelial cells disappeared, so the density of endothelium was also decreased. The empty spaces were replaced by the expansion of adjacent cells.

• Journal of the Korea Institute of Building Construction
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• v.13 no.6
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• pp.530-540
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• 2013

The business environment that affects the management performance can be characterized by each Strategic Business Unit (SBU) since construction companies win overseas contracts due to the fairly good construction situations while experience a decline in the local housing market. Environmental changes can alter the strategic importance of the SBU when measuring the management performance. However, large construction companies apply BSC (Balanced Score Card) for collective calculation to determine the management performance, making it difficult to reflect the strategic importance of SBU. This method may create a distorted image of management performance that fails to take environmental changes into consideration, and as such it needs to be improved. Yet, there are no studies on the weight of each SBU considering environmental changes. Thus, the current study intends to analyze the weight of SBU for company-wide measurement of the performance of large construction companies. In addition, a model for analysis of SBU importance is proposed to respond to the constantly changing environmental situations and to modify the weight. For analysis of SBU weight, a questionnaire was conducted with 23 experts and hands-on workers, and the questionnaire result was quantitatively analyzed by applying the FD-AHP method. It is expected that the result will enable a model to be proposed to calculate the weight per division in a manner that reflects environmental changes and minimizes strategic distortion when measuring the management performance of large construction companies.

• Progress in Medical Physics
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• v.19 no.4
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• pp.269-275
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• 2008

Although MR imaging is generally applicable to depict knee joint deterioration it, is sometimes occurred to mis-read and mis-diagnose the common knee joint diseases. In this study, we employed magnetization transfer ratio (MTR) method to improve the diagnosis of the various knee joint diseases. Spin-echo (SE) T2-weighted images (TR/TE 3,400-3,500/90-100 ms) were obtained in seven cases of knee joint deterioration, FSE T2-weighted images (TR/TE 4,500-5,000/100-108 ms) were obtained in seven cases of knee joint deterioration, gradient-echo (GRE) T2-weighted images (TR/TE 9/4.56/$50^{\circ}$ flip angle, NEX 1) were obtained in 3 cases of knee joint deterioration, In six cases of knee joint deterioration, fat suppression was performed using a T2-weighted short T1/tau inverse recovery (STIR) sequence (TR/TE =2,894-3,215 ms/70 ms, NEX 3, ETL 9). Calculation of MTR for individual pixels was performed on registration of unsaturated and saturated images. After processing to make MTR images, the images were displayed in gray color. For improving diagnosis, three-dimensional isotropic volume images, the MR tristimulus color mapping and the MTR map was employed. MTR images showed diagnostic images quality to assess the patients' pathologies. The intensity difference between MTR images and conventional MRI was seen on the color bar. The profile graph on MTR imaging effect showed a quantitative measure of the relative decrease in signal intensity due to the MT pulse. To diagnose the pathologies of the knee joint, the profile graph data was shown on the image as a small cross. The present study indicated that MTR images in the knee joint were feasible. Investigation of physical change on MTR imaging enables to provide us more insight in the physical and technical basis of MTR imaging. MTR images could be useful for rapid assessment of diseases that we examine unambiguous contrast in MT images of knee disorder patients.