• 대한의용생체공학회:의공학회지
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• 제35권5호
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• pp.132-141
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• 2014

In an ordinary CT scan, a large number of projections with full field-of-view (FFOV) are necessary to reconstruct high resolution images. However, excessive x-ray dosage is a great concern in FFOV scan. Region-of-interest (ROI) CT or sparse-view CT is considered to be a solution to reduce x-ray dosage in CT scanning, but it suffers from bright-band artifacts or streak artifacts giving contrast anomaly in the reconstructed image. In this study, we propose an image reconstruction method to eliminate the bright-band artifacts and the streak artifacts simultaneously. In addition to the ROI scan for the interior projection data with relatively high sampling rate in the view direction, we get sparse-view exterior projection data with much lower sampling rate. Then, we reconstruct images by solving a constrained total variation (TV) minimization problem for the interior projection data, which is assisted by the exterior projection data in the compressed sensing (CS) framework. For the interior image reconstruction assisted by the exterior projection data, we implemented the proposed method which enforces dual data fidelity terms and a TV term. The proposed method has effectively suppressed the bright-band artifacts around the ROI boundary and the streak artifacts in the ROI image. We expect the proposed method can be used for low-dose CT scans based on limited x-ray exposure to a small ROI in the human body.

• 대한방사선기술학회지:방사선기술과학
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• 제46권5호
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• pp.417-425
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• 2023

The glomerular filtration rate (GFR) has been the subject of much research as a key indicator for diagnosing, treating, and monitoring kidney function. The gamma camera method (Gates method) is simple and allows simultaneous acquisition of GFR and renal scintigraphy for each kidney, however its accuracy is inferior. This study aimed to investigate changes in GFR depending on how region of interest (ROI) are set up, which is one of many factors influencing accuracy. GFR was calculated by setting the ROI for each phase of the image acquisition time (Gates-1: 0~1 minutes, Gates-2: 1~3 minutes, Gates-3: 3~27 minutes), and statistical significance was verified based on probability value 0.05 through ANOVA analysis. While there was no statistically significant difference among results from Gates-1, 2, 3 (p=0.481>0.05), overall results from the Gates method tended to overestimate compared to those from the multiple blood sampling-dual exponential (MBSDE) method. When comparing averages between phases, results from Gates-2 were most similar to those from the MBSDE method. Moreover, paired t-test p-values between MBSDE method and phases were as follows Gates-1: 0.021 (p<0.05), Gates-2: 0.280 (p>0.05), and Gates-3: 0.164 (p>0.05) indicating that only Gates-1 had statistically significant differences compared with MBSDE method. Thus, setting ROI around 2~3 minutes is calculated can aid in accurately determining GFR when Gates Method.

• Current Optics and Photonics
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• 제1권3호
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• pp.239-246
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• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• 한국멀티미디어학회논문지
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• 제18권1호
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• pp.1-8
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• 2015

In recent years, ear has emerged as a new biometric trait, because it has advantage of higher user acceptance than fingerprint and can be captured at remote distance in an indoor or outdoor environment. This paper proposes an individual identification method using ear region based on SIFT(shift invariant feature transform). Unlike most of the previous studies using rectangle shape for extracting a region of interest(ROI), this study sets an ROI as a flexible expanded region including ear. It also presents an effective extraction and matching method for SIFT keypoints. Experiments for evaluating the performance of the proposed method were performed on IITD public database. It showed correct identification rate of 98.89%, and it showed 98.44% with a deformed dataset of 20% occlusion. These results show that the proposed method is effective in ear recognition and robust to occlusion.

• 한국컴퓨터정보학회논문지
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• 제19권8호
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• pp.35-44
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• 2014

본 논문에서는 효율적인 핸드 마우스를 위한 3D 포인팅 인터페이스에 대해 제안한다. 제안하는 방법에서는 조명과 환경 변화에 강건하기 위해 깊이영상을 이용하고, 손바닥의 법선벡터를 이용하여 3D 포인팅을 구성한다. 먼저, 손 영역 검출과 추적은 기존 방법을 이용하고, 이로부터 획득한 정보를 바탕으로 손바닥의 영역을 예측하여 관심 영역을 획득한다. 관심 영역을 획득하면, 해당 영역을 평면의 방정식으로 근사시키고, 법선 벡터를 추출한다. 다음으로, 안정적인 제어를 위해 추출한 법선 벡터를 이용하여 보간을 수행하고, 교점을 검출한다. 검출된 교점은 안정성과 효율성을 위해 시그모이드 함수를 이용한 동적 가중치가 적용되고, 최종적으로 2D 좌표계로 변환된다. 본 논문에서는 관심 영역, 방향 벡터 검출 방법에 대해 설명하고 안정적인 제어를 위한 보간 방법과 동적 가중치 적용방법에 대해 제안한다. 마지막으로 제안된 3D 포인팅의 정성적, 정량적 분석을 통해 안정적인 제어 가능성을 입증한다.

• 한국통신학회논문지
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• 제38C권12호
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• pp.1114-1125
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• 2013

License Plate Detection (LPD) is a key component in automatic license plate recognition system. Despite the success of License Plate Recognition (LPR) methods in the past decades, the problem is quite a challenge due to the diversity of plate formats and multiform outdoor illumination conditions during image acquisition. This paper aims at automatical detection of car license plates via image processing techniques. In this paper, we proposed a real-time and robust method for license plate detection using Heuristic Energy Map(HEM). In the vehicle image, the region of license plate contains many components or edges. We obtain the edge energy values of an image by using the box filter and search for the license plate region with high energy values. Using this energy value information or Heuristic Energy Map(HEM), we can easily detect the license plate region from vehicle image with a very high possibilities. The proposed method consists two main steps: Region of Interest (ROI) Detection and License Plate Detection. This method has better performance in speed and accuracy than the most of existing methods used for license plate detection. The proposed method can detect a license plate within 130 milliseconds and its detection rate is 99.2% on a 3.10-GHz Intel Core i3-2100(with 4.00 GB of RAM) personal computer.

• 디지털융복합연구
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• 제10권7호
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• pp.123-128
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• 2012

본 논문에서는 보다 정확한 물체 인식을 위하여 물체의 특징점 검출 시스템을 제안한다. 물체의 특징점 검출 시스템은 학습 단계와 검출 단계로 구분된다. 학습 단계에서는 각 특징점의 탐색영역을 설정하기 위한 관심영역모델과 탐색영역에서 특징점을 검출하기 위한 각 특징점별 검출기를 생성한다. 검출 단계에서는 학습 단계에서 생성했던 관심영역모델을 이용하여 입력 영상에서 각각의 특징점의 탐색영역을 설정한다. 시스템에서 검출하고자 하는 특징점 검출 방법은 고속 푸리에 변환을 이용하기 때문에 검출 속도가 빠르며 물체의 추적 시 실패하는 확률이 낮아진다. 제안하는 방법을 개발하여 실험 영상에 적용한 결과 추적하고자 하는 물체가 불규칙적인 속도로 움직일 때에도 안정적으로 추적함을 알 수 있었다. 실험 결과는 기존의 방법들에서 사용되었던 다양한 데이터 집합에 적용하였을 때 우수한 성능을 보여준다.

• 한국음향학회지
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• 제37권2호
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• pp.118-128
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• 2018

본 논문은 사이드 스캔 소나 영상을 컨볼루션 신경망으로 학습하여 수중물체를 탐색하는 방법을 다루었다. 사이드 스캔 소나 영상을 사람이 직접 분석하던 방법에서 컨볼루션 신경망 알고리즘이 보강되면 분석의 효율성을 높일 수 있다. 연구에 사용한 사이드 스캔 소나의 영상 데이터는 미 해군 수상전센터에서 공개한 자료이고 4종류의 합성수중물체로 구성되었다. 컨볼루션 신경망 알고리즘은 관심영역 기반으로 학습하는 Faster R-CNN(Region based Convolutional Neural Networks)을 기본으로 하며 신경망의 세부사항을 보유한 데이터에 적합하도록 구성하였다. 연구의 결과를 정밀도-재현율 곡선으로 비교하였고 소나 영상 데이터에 지정한 관심영역의 변경이 탐지성능에 미치는 영향을 검토함으로써 컨볼루션 신경망의 수중물체 탐지 적용성에 대해 살펴보았다.

• Journal of Information Processing Systems
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• 제11권4호
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• pp.601-615
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• 2015

Region of interest (ROI) is the most informative part of a medical image and mostly has been used as a major part of watermark. Various shapes ROIs selection have been reported in region-based watermarking techniques. In region-based watermarking schemes an image region of non-interest (RONI) is the second important part of the image and is used mostly for watermark encapsulation. In online healthcare systems the ROI wrong selection by missing some important portions of the image to be part of ROI can create problem at the destination. This paper discusses the complete medical image availability in original at destination using the whole image as a watermark for authentication, tamper localization and lossless recovery (WITALLOR). The WITALLOR watermarking scheme ensures the complete image security without of ROI selection at the source point as compared to the other region-based watermarking techniques. The complete image is compressed using the Lempel-Ziv-Welch (LZW) lossless compression technique to get the watermark in reduced number of bits. Bits reduction occurs to a number that can be completely encapsulated into image. The watermark is randomly encapsulated at the least significant bits (LSBs) of the image without caring of the ROI and RONI to keep the image perceptual degradation negligible. After communication, the watermark is retrieved, decompressed and used for authentication of the whole image, tamper detection, localization and lossless recovery. WITALLOR scheme is capable of any number of tampers detection and recovery at any part of the image. The complete authentic image gives the opportunity to conduct an image based analysis of medical problem without restriction to a fixed ROI.

• 한국정보통신학회논문지
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• 제11권11호
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• pp.2127-2134
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• 2007

전자적인 학습은 이동성 및 접근의 용이성, 즉시성, 유연성을 제공하여 학습자의 시간적인 제약을 극복할 수 있었으나 유선 컴퓨터상에서 공간에 의한 제약은 많은 문제로 남아있다. 따라서 이런 전자적인 학습은 학습자에게 시간과 공간적인 제약을 극복할 수 있는 모바일 학습 환경으로 변화하는 추세이다. 그러나 모바일 디바이스들은 작은 디스플레이 사이즈로 인하여 실시간 동영상에서 제공되는 학습 내용을 정확하게 인식하기는 어려운 실정이다. 따라서 본 논문은 실시간 학습 영상을 관심 영역에 대한 학습 영역을 추출하고 작은 디스플레이 디바이스 사이즈에 적절한 영상 크기로 축소하여 무선 PDA에 디스플레이하는 기법을 제안한다. 실험 결과, 다양한 강의 영상에서 학습 내용 중심의 영역을 적응적으로 추출하고, 사용자 디바이스 사이즈에 적합한 영역을 효과적으로 계산함으로써 계산에 소요되는 시간을 크게 줄일 수 있었다.