• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.679-684
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• 2023

Venous puncture is widely used to obtain blood samples for pathological examination. Because the invasive venipuncture method using a needle is repeatedly performed, the pain suffered by the patient increases, so our research team pre-developed a miniaturized near-infrared (NIR) imaging system in advance. To improve the image quality of the acquired NIR images, this study aims to model the non-local means (NLM) algorithm, which is well known to be efficient in noise reduction, and analyze its applicability in the system. The developed NIR imaging system is based on the principle that infrared rays pass through dichroic and long-pass filters and are detected by a CMOS sensor module. The proposed NLM algorithm is modeled based on the principle of replacing the pixel from which noise is to be removed with a value that reflects the distances between surrounding pixels. After acquiring an NIR image with a central wavelength of 850 nm, the NLM algorithm was applied to segment the final vein area through histogram equalization. As a result, the coefficient of variation of the NIR image of the vein using the NLM algorithm was 0.247 on average, which was an excellent result compared to conventional filtering methods. In addition, the dice similarity coefficient value of the NLM algorithm was improved by 62.91 and 9.40%, respectively, compared to the median filter and total variation methods. In conclusion, we demonstrated that the NLM algorithm can acquire accurate segmentation of veins acquired with a NIR imaging system.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.8-17
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• 2008

This paper proposes a robust license plate extraction method from images taken under unconstrained environments. Utilization of the color and the edge information in complementary fashion makes the proposed method deal with not only various lighting conditions, hilt blocking artifacts frequently observed in compressed images. Computational complexity is significantly reduced by applying Hough transform to estimate the skew angle, and subsequent do-skewing procedure only to the candidate regions. The true plate region is determined from the candidates under examination using clues including the aspect ratio, the number of zero crossings from vertical scan lines, and the number of connected components. The performance of the proposed method is evaluated using compressed images collected under various realistic circumstances. The experimental results show 94.9% of correct license plate extraction rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2530-2538
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• 2015

The pixel value of depth image is depth value so that different objects which are placed on nearby position have similar pixel value. Moreover, the pixels of depth image have distinct pixel values compared to adjacent pixels while those of color image has very similar values. Accordingly distorted depth image of multiview video plus depth (MVD) needs proper error concealment methods considering the characteristics of depth image when transmission errors are happened. In this paper, classifying regions of depth image to consider edge directions and then applying adaptive error concealment methods to each region are proposed. Recovered depth images utilize with multiview video data to synthesize intermediate-view point video. The synthesized view is evaluated by objective quality metrics to demonstrate proposed method performance.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.51-57
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• 2005

In this paper, we propose an adaptive contrast control method for the flat real-time processing. The proposed method has employed probability density function(PDF) in order to control a sudden change in image-brightness. In addition, the proposed algerian obtains the maximum contrast without affecting the processed image. In order to reduce hardware complexity, we have utilized approximated CDF based on sampling values. Visual test and standard deviation of their histogram have been introduced to evaluate the resultant output images of at: proposed method and the original ones.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.46-49
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• 2019

본 논문에서는 구역을 나눔으로써 상황에 따라 강조하고 싶은 부분을 부각시키는 방법을 활용하여 히스토그램을 처리하는 기법을 제안한다. 기존의 히스토그램 스케일링과 평활화 방법은 간단한 알고리듬으로 사용이 편하지만 쓸 수 없는 상황이 존재한다. 먼저 히스토그램 스케일링에서는 사진이 갖고 있는 명암 최댓값과 최솟값을 늘리는 방법이지만, 범위를 늘릴 수 없는 경우에는 이 방법이 제한된다. 히스토그램 평활화는 사진이 갖고 있는 명암의 히스토그램 누적분포함수 (CDF)가 일정한 기울기를 갖게 변환하는 방법이다. 이 방법에서는 밝기 변화가 거의 없었던 부분에서 품질이 낮아지는 단점이 있다. 제안하는 알고리듬은 영상에서 강조하고 싶은 부분을 설정한 뒤, 구역을 나눔으로써 기존의 히스토그램 스케일링과 히스토그램 평활화의 단점을 개선했다. 제안한 알고리듬을 평가하기 위해서 주관적인 지표로 20명을 대상으로 설문을 진행하였다. 블라인드 테스트로 원본과, 기존의 히스토그램 처리 기법을 이용한 영상, 제안된 히스토그램 처리 기법을 이용한 영상을 비교하였다. 실험 결과를 통해 제안된 알고리듬이 기존의 알고리듬보다 영상의 화질을 개선했음을 확인했다.

• Journal of IKEEE
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• v.22 no.1
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• pp.68-73
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• 2018

In this paper, we propose an efficient algorithm for mapping a $360^{\circ}$ circular image to a planar image. The proposed algorithm consists of obtaining size of the planar image, calculating the distance between the camera and the planar image, calculating horizontal angle of camera and planar image, calculating vertical angle between camera and planar image, calculating the position of a pixel that matches pixels in a $360^{\circ}$ circular image to pixels in a planar image. Experiments were performed to evaluate the efficient algorithm for mapping the proposed $360^{\circ}$ circular image to the plane image. The reconstruction rate of the mapped plane image was confirmed 99% and the image quality of the mapped plane image was confirmed 72%. Since the results were higher than the standard values of commercial software, the effectiveness of the algorithm was confirmed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.77-80
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• 2009

3차원 영상 처리 기술과 3차원 디스플레이의 발전은 3차원 영상 시장의 빠른 발전을 가져왔고 차세대 방송 기술로 큰 관심을 받고 있다. 하지만 3차원 영상은 시청할 때 눈의 피로, 어지럼증과 같은 현상이 일어날 수 있으며, 왜곡된 3차원 영상이 인체에 해로운 영향을 미칠 수도 있다. 이는 3차원 영상 산업의 활성화를 위해서 가장 시급히 해결되어야 할 문제이다. 현재 3차원 디스플레이는 스테레오 방식과 함께 1view 1depth 다시점 방식이 개발되었다. 특히 1view 1depth 다시점 디스플레이에서 깊이 영상의 공간적/시간적으로 복잡한 정도는 피로감을 일으키는 주요 요소이며 이는 1view 1depth 영상을 통해 직접 연구할 수 있다. 본 논문에서는 1view 1depth 디스플레이에서 주관적인 피로도와 큰 상관도를 가지는 깊이 영상의 특성 측정 방법을 제안한다. 1view 1depth 디스플레이에서 view 영상은 양호한 화질을 가정하였으며 피로감에 큰 영향을 미치는 깊이 영상 정보만 사용하여 공간적, 시간적인 특성을 분석한다. 공간적 복잡도는 각 프레임에 대하여 깊이 영상 내 화소 값의 분산 값을 취하여 공간적으로 깊이 값의 분포와 구조의 복잡한 정도를 측정하고, 시간적 복잡도는 연속적인 프레임에 대하여 동일한 화소위치에서 화소 값 차이의 분산 값을 사용한다. 또한 공간적/시간적 평균값의 측정하여 피로감에 영향을 주는 요인으로 사용하였다. 결과적으로 측정한 값들을 바탕으로 주관적인 피로도 평가와 유사성을 가지도록 모델링하여 3차원 영상의 피로도를 예측한다.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.1004-1013
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• 2012

3D images and videos are required viewers to wear 3D glasses. According to the data, about half of Korean people wear glasses or contact lens and this implies 3D video viewers may have a trouble due to putting a pair of 3D glasses atop their glasses. The purpose of this study is to examine gamers' perceived characteristics, presence, and fatigue according to video gaming display (2D vs. 3D) and glasses whether wearing or not. The results show that the interaction effect of the display and wearing glasses was statistically significant in the perceived presence, and the main effect of the display was statistically significant in the perceived characteristics and fatigue.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.23-30
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• 2018

To evaluate the effect of patient size on effective dose and image quality for Digital Chest Tomosynthesis(DTS) using additional 0.3 mm copper filtration. Eighty artificial nodules were placed in the thorax phantom("Lungman," Kyoto Kagaku, Japan), and Digital Chest Tomosynthesis(DTS) images of the phantom were acquired both with and without added 0.3 mm Cu filtration. To simulate patients of three sizes: small, average size and oversize, one or two 20-mm-thick layer of PMMA(polymethyl methacrylatek) blocks were placed on the phantom. The Effective dose was calculated using Monte Carlo simulations. Two evaluations of image quality methods have been employed. Three readers counted the number of nodules detected in the lung, and the measured contrast-to-noise ratios(CNRs) were used. Data were analyzed statistically. The ED reduced $26{\mu}Sv$ in a phantom, $33{\mu}Sv$ in one 20-mm-thick layer of PMMA block placed on the phantom, and $48{\mu}Sv$ in two 20-mm-thick layer of PMMA blocks placed on the phantom. The Effective dose(ED) differences between DTS with and without filtration were significant(p<0.05). In particular, when we used two 20-mm-thick layer of PMMA blocks placed on the phantom, the ED was significantly reduced by 36% compared with those without additional filtration. Nodule detection sensitivities were not different between with and without added filtration. Differences of CNRs were statistically insignificant(p>0.05). Use of additional filtration allows a considerable dose reduction during Digital Chest Tomosynthesis(DTS) without loss of image quality. In particular, additional filtration showed outstanding result for effective dose reduction on two 20-mm-thick layer of PMMA blocks placed on the phantom. It applies to overweight patients.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.53-63
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• 2006

A discrete wavelet transform(DWT)-based image watermarking algorithm is proposed in this paper, the proposed method decompose the original image into four subsampled images. Subsampled images are transformed by 2 level DWT, respectively. The proposed method embeds the watermark into one of the subsampled DWT images using edge table that represents dege characteristics of the original image. Without an original image, a watermark is extracted through comparison one subsampled DWT image inserted the watermark with the rest of the submapled DWT images. many exiting methodes do not adequately estimate edge regions where intensities are changed abruptly. The proposed method address with an edge table. Also, even if the watermark is embedded into a low frequency area, our method preserves the image quality. The vality of the proposed method is demonstrated through the PSNR test and subjective image quality that human eyes feel.