• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.926-932
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• 2017

Image distortion can occur when photographing deep sea targets with an optical camera. This problem arises because sunlight is not sufficiently transmitted due to seawater and various floating particles of dust. Particularly, color distortion takes place, causing green and blue color channels to be over emphasized due to water depth, while distortion of boundaries also occurs due to light refraction by seawater and floating particles of dust. These distortions degrade the overall quality of underwater images. In this paper, we analyze underwater images of the bottom of vessels. Based on the results, we propose a technique for color correction and edge enhancement. Experimental results show that the proposed method increases edge clarity by 3.39 % compared to the effective edges of the original underwater image. In addition, a quantitative evaluation and subjective image quality evaluation were concurrently performed. As a result, it was confirmed that object boundaries became clear with color correction. The color correction and contour enhancement method proposed in this paper can be applied in various fields requiring underwater imaging in the future.

• Journal of the Korean Society of Radiology
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• v.8 no.5
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• pp.271-278
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• 2014

The purpose of this study is to know optimized fat suppression techniques for brachial plexus compared with STIR and SPAIR T1, T2 techniques. A total of 30 normal volunteers without brachial plexus disease were studied on a 3.0 T MRI scanner. As an analytical method, SNR, CNR, 4-point grading scale were evaluated by using three pulse sequences. As a quantitative analysis, the SNR, CNR for SPAIR T1 technique provided high value in branchial plexus roots (03.07, -2.25), branchial plexus trunks(06.70, 36.31)(p<0.05). As a qualitative Analysis, The visibility for delineation of brachial plexus, fat suppression, artifact was significantly better on SPAIR T1(3.2, 3.6, 3.4) technique(p<0.05).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.178-181
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• 2012

본 논문에서는 퍼지 콘트라스트와 HOG 기법을 이용한 감시 시스템을 제안한다. 제안된 감시 시스템은 감시 영상에서 명암 대비를 강조하기 위해 퍼지 콘트라스트 기법을 적용한 후, 감시 전/후 영상에 Substraction기법을 적용한다. Substraction 기법이 적용된 영상에서 히스토그램의 변화가 클 경우에는 침입자의 침입으로 간주한다. 침입으로 간주된 영상에서 감시 대상의 물체를 감시할 영상과 침입자를 실시간으로 추적하기 위한 영상으로 구분한다. 감시 대상의 물체를 감시할 영상에서는 퍼지 이진화를 적용한다. 퍼지 이진화를 적용한 영상에서 Blob 기법을 적용하여 객체화한 후, 침입된 침입자의 영상을 저장한다. 침입자를 실시간으로 추적할 영상에서는 HOG 기법을 적용한 후, SVM을 이용하여 움직이는 사람의 객체를 추적한다. 제안된 방법을 실시간 영상에 적용한 결과, 제안된 감시 시스템이 효율적으로 침입자를 감시하는 것을 확인할 수 있었다.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.119-128
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• 2007

Purpose : The purpose of this study was a phantom study to measure the diffusion properties of water molecules by steady-state free precession diffusion-weighted imaging (SSFP- DWI) with a low b-value and to determine if this sequence might be useful for application to the evaluation of bone marrow pathology. Materials and methods : 1. The phantom study: A phantom study using two diffusion weighted sequences for the evaluation of the diffusion coefficient was performed. Three water-containing cylinders at different temperatures were designed: phantom A was $3^{\circ}C$, B was $23^{\circ}C$ and C was $63^{\circ}C$. Both SSFP and echo planar imaging (EPI) sequences (b-value: $1000s/mm^2$) were performed for comparison of the diffusion properties. The Signal to noise ratios (SNR) and apparent diffusion coefficient (ADC) values of the three phantoms using each diffusion-weighted sequence were assessed. 2. The Clinical study: SSFP-DWI was performed in 28 patients [sacral insufficiency fractures (10), osteoporotic lumbar compression fractures (10), malignant compression fractures (8)]. To measure the ADC maps, a diffusion-weighted single shot stimulated echo-acquisition mode sequence ($650s/mm^2$) was obtained using the same 1.5-T MR imager Results : For the phantom study, the signal intensity on the SSFP as well as the classic EPI-based DWI was decreased as the temperature increased in phantom A to C. The ADC values of the phantoms on EPI-DWI were $0.13{\times}10^{-3}mm^2/s$ in phantom A, $0.22{\times}10^{-3}mm^2/s$ in B and $0.37{\times}10^{-3}mm^2/s$. in C. The SSFP can be regarded as a DWI sequence in view of the series of signal decreases. Conclusion : Bone marrow pathologies with different diffusion coefficients were evaluated by SSFP-DWI. All benign fractures were hypointense compared to the adjacent normal bone marrow where as the malignant fractures were hyperintense compared to the adjacent normal bone marrow.

• Investigative Magnetic Resonance Imaging
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• v.6 no.2
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• pp.166-172
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• 2002

Purpose : To evaluate the usefulness of diffusion-weighted imaging(DWI) and quantitative apparent diffusion coefficient (ADC) maps in the patients with spinal cord infarction. Materials and methods : We studied 6 patients presented symptoms with spinal cord infarction, retrospectively (3 men and 3 women). We obtained multi-shot echo planar-based, DWI using 1.5T MR scanner at 5.4 mean days after the onset of ischemic symptoms. In six patients, signal intensity was acquired at conventional b value $1000s/\textrm{mm}^2$). The ADC value for the normal spinal cord and for infarcted lesions was measured from the trace ADC maps by using regions of interest positioned over the spinal cord. We analyzed signal intensity of lesion on MRI and DWI, and compared with ADC values in infarcted lesions and normal site. Results : T1-weighted MR image showed isosignal intensity in four of six patients and low signal intensity in two of six. T2-weighted MR image demonstrated high signal intensity in all of six. All DWI were considered to be diagnostic. All of six depicted a bright signal intensity on DWI. ADC values of infarcted lesion were measured lower than that of normal spinal cord on ADC map. The differences in ADC values between infarcted and normal spinal cord were significantly different (p＜0.05). Conclusion : It is possible to obtain DWI and ADC map of the spinal cord and DWI may be useful in the early diagnosis and localization of lesion site in patients with spinal cord infarction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4962-4969
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• 2013

The purpose of this experiment is to evaluate of optimized FS techniques for T2 weighted abdominal MRI compared of TSE-SPIR fat suppression and GE-PROSET fat suppression. All MR examinations were performed on a 1.5 T(Philips, Medical System, Achieva) scanner using 16 channel mult-coils. All images were performed in the axial plane using TSE-SPIR and GE-PROSET. The mean SNRs of the retroperitoneal and mesenteric fat for TSE-SPIR and GE-PROSET were 31.50, 4.15 and 32.39, 7.03. The mean CNRs of the bowel and retroperitoneal, mesenteric fat for TSE-SPIR and GE-PROSET were 52.69, 74.54 and 26.12, 68.78). The delineation of bowel wall margins with TSE-SPIR(2.4) and GE-PROSET(1.8) were significantly improved using TSE-SPIR. The delineation of pancreas wall with TSE-SPIR(1.90), GE-PROSET(2.80) were significantly improved using GE-PROSET. In conclusion, TSE-SPIR fat suppression was superior to GE-PROSET fat suppression in T2 WI FS abdominal MRI.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.724-726
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• 2005

지금까지의 컴퓨터 그래픽스의 방향은 사진과 유사하게 표현하는 Photorealism이 강세였으나, 최근 각종 기술문서나 의학, 교육등 많은 분야에서 사진과 같은 컴퓨터 그래픽스보다는 사물의 특징을 강조하고, 불필요한 부분을 생략해서 표현하는 비사실적 렌더링(Non-Photorealistic Rendering)분야가 새롭게 떠오르고 있다. 비실사기법을 통해 생성된 이미지는 사물의 특징을 부각시켜 시현함으로서 사진과 같은 사실적인 묘사보다는 사물의 특징을 통한 의미전달에 초점을 둔 렌더링 기법이라 할 수 있다. 비실사기법에는 수채화, 수묵화, 유화, 목탄화, 데생과 같은 미술기법과 만화와 같이 표현하는 Cartoon Rendering등 다양한 분야가 있지만 본 논문에서는 모든 그림의 기본 요소가 되는 정을 이용하여 사물을 표현하는 점묘법을 적용한 비실사기법에 대해서 이미 발표된 논문을 살펴보고, 새로운 기법을 제안하고자 한다.

• Spatial Information Research
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• v.13 no.4 s.35
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• pp.345-354
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• 2005

Super resolution image reconstruction method refers to image processing algorithms that produce a high resolution(HR) image from observed several low resolution(LR) images of the same scene. This method has proven to be useful in many practical cases where multiple frames of the same scene can be obtained, such as satellite imaging, video surveillance, video enhancement and restoration, digital mosaicking, and medical imaging. In this paper, we applied the super resolution reconstruction method in spatial domain to video sequences. Test images are adjacently sampled images from continuous video sequences and are overlapped at high rate. We constructed the observation model between the HR images and LR images applied with the Maximum A Posteriori(MAP) reconstruction method which is one of the major methods in the super resolution grid construction. Based on the MAP method, we reconstructed high resolution images from low resolution images and compared the results with those from other known interpolation methods.

• Journal of Broadcast Engineering
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• v.3 no.1
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• pp.39-49
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• 1998

머지않아 가상현실 기법은 TV 프로그램 제작에 큰 영향을 미칠 것이다. 한 예로서, 이미 수년 전부터 가상 스튜디오는 제한적으로나마 프로그램 제작에 도입되기 시작하였다. 본 논문에서는 가상현실 기법을 이용한 또 다른 응용시스템을 소개한다. 가상 스테이지라고 이름 붙인 본 시스템은 가상 스튜디오와 개념적으로 흡사하나 가상세계 참여자의 상호작용을 더욱 강조하고 있다. 본 연구에서 가상 스테이지는 일종의 카라오케 형태로 구현되었으나 실제로는 TV쇼 프로그램 등, 다양한 프로그램 제작에 사용 가능하다.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.73-75
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• 2012

최근 스마트폰 사용자가 증가함에 따라 스마트폰 사용에 대한 공공장소에서의 에티켓에 대한 중요성이 강조되고 있다. 그럼에도 불구하고 사용자가 도서관 등 정숙을 지켜야 할 장소에서 휴대 전화에 의해 발생되는 소음을 완전히 차단하지 못하고 있다. 본 논문에서는 이러한 문제를 해결하기 위해 스마트폰의 위치 기반 서비스를 이용하여 위치 정보를 분석하고 그 장소에 맞는 볼륨, 진동 등과 같은 모바일 디바이스의 설정을 자동 또는 수동으로 변경할 수 있게 해주는 기법을 적용한 어플리케이션을 제안한다.