• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권5호
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• pp.231-240
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• 2015

의료 영상은 원본 콘텐츠의 품질을 유지하는 것이 중요한 동시에 사생활 보호의 요구가 증가함에 따라서 가역 워터마킹 기술에 대한 필요성이 증가하고 있다. 기존의 가역 워터마킹 알고리즘은 의료 영상이 아닌 일반 영상에서는 고용량 고품질을 유지할 수 있으나 영상 전체에 왜곡을 야기한다. 따라서 촬영 대상물의 품질 유지가 중요한 의료 영상에 직접적으로 적용하기에는 부적합하다는 단점을 가진다. 본 논문에서는 의료 영상의 촬영 대상물 영역의 영상 품질을 유지하며, 워터마크를 효율적으로 삽입할 수 있는 가역 워터마킹 알고리즘을 제안한다. 먼저 대상물과 배경 영역을 분할하기 위한 알고리즘을 설계하고, 그 후에 분할된 대상물과 배경에 대해 추정오차 히스토그램에 기반하여 가역 워터마킹 기법을 적용한다. 대상물 영역에는 삽입 레벨을 낮게 설정하고, 배경 영역에 삽입 레벨을 높게 설정함으로써 대상물의 화질은 최소한으로 변형을 하며 효율적인 삽입이 가능하도록 하였다. 실험에서 다양한 의료 영상에 대하여 제안한 알고리즘을 기존 추정오차 히스토그램 기반 가역 워터마킹 기술과 삽입 용량 및 영상 품질에 대한 비교를 수행하였고, 그 결과 제안하는 알고리즘이 기존 알고리즘에 비해 높은 영상 품질을 유지하면서 우수한 삽입 용량을 얻을 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제12권5호
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• pp.39-54
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• 2012

오늘날 의료정보화 수준향상과 디지털 병원화의 흐름에 따라 PACS는 의료기관의 핵심 인프라 중 하나로 자리매김하였다. 이와 함께 생산되는 디지털 의료영상의 종류 및 의료영상 데이터가 양적으로 급증하고 있으며, 이는 의료영상 데이터의 효과적인 보관을 위한 의료영상 압축을 중요한 요소로 부각시킨다. 현재 의료영상에 관한 사실상의 표준인 DICOM 규격에서는 의료영상 압축을 위하여 무손실 압축기법인 RLE를 명시하고 있으나, 무손실 범용 압축기법인 RLE는 인체의 대칭성을 가지는 많은 의료영상에 적용하면 높은 압축율 기대하기 힘들다. 이 논문에서는 다양한 의료영상 중 대칭 특성을 크게 내포하는 뇌 CT 영상을 대상으로 하여 영상 내 관심영역을 검출하고 대칭특성에 따라 영상의 픽셀 값을 재코딩하는 전처리 하고 영상을 압축하는 기법을 제안한다. 실험에 의하면, 제안한 기법은 RLE 압축과 영상 내 관심영역을 검출하지 않고 압축할 때와 비교하여 높은 압축률을 보인다.

• 국제물리치료학회지
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• 제11권1호
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• pp.2005-2011
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• 2020

Background: Motor imagery is the mental representation of an action without overt movement or muscle activation. However, few previous studies have demonstrated motor imagery training effects as an objective assessment tool in patients with early stroke. Objective: To investigate the effect of motor imagery training on Somatosensory Evoked Potentials (SSEP) and upper limb function of stroke patients. Design: A quasi-experimental study. Methods: Twenty-four patients with stroke were enrolled in this study. All subjects were assigned to the experimental or control group. All participants received traditional occupational therapy for 30 minutes, 5 times a week. The experimental group performed an additional task of motor imagery training (MIT) 20 minutes per day, 5 days a week, for 4 weeks. Both groups were assessed using the SSEP amplitude, Fugl-Meyer assessment of upper extremity (FMA UE) and Wolf motor function test. Results: After the intervention, the experimental group showed significant improvement in SSEP amplitude and FMA UE than did the control group. Conclusion: These findings suggest that the MIT effectively improve the SSEP and upper limb function of stroke patients.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.246-251
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• 1998

This paper proposes a new building segmentation method from 1m resolution imagery using an Active Contour Model, known as "Balloons". The original balloons, which was designed by Cohen(Cohen, 1991) to extract features from medical images, are modified for building segmentation. The proposed method consists of two phases. Firstly, building boundaries are extracted by balloons with a given position on buildings from an operator. Since balloons actively adjust their shapes according to the boundaries, there is no more shape limitations on detecting buildings. Secondly, buildings are segmented by connecting the corners detected from the building boundaries, because most buildings, which are man-made objects, are effectively described by polygons. The test results show that most buildings are segmented efficiently and easily. The proposed method is new and timely as 1m resolution spaceborne imagery will be available in the very near future. The proposed method can be used fur operational building segmentation from such imagery.

• Archives of Plastic Surgery
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• 제42권5호
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• pp.635.1-635.1
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• 2015

• The Journal of Korean Physical Therapy
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• 제25권5호
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• pp.273-281
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• 2013

Purpose: The purpose of this study is to determine the effect of motor imagery training on residual upper extremity strength and activities of daily living of chronic cervical spinal cord injury patients. Methods: Twelve ASIA A B patients, who had more than a 12-month duration of illness and C5 or 6 motor nerve injury level, were randomly divided into experimental group (n=6) and control group (n=6). Patients in the experimental group performed motor imagery training for five minutes prior to general muscle strengthening training, while those in the control group performed general muscle strengthening training only. The training was performed five times per week, 30 minutes per day, for a period of four weeks. General muscle strengthening training consisted of a progressive resistive exercise for residual upper extremity. Motor imagery training consisted of imagining this task performance. Before and after the training, EMG activity using BTS Pocket Electromyography and Spinal Cord Independent Measure III(SCIM III) were compared and analyzed. Results: The residual upper extremity muscle strengths showed improvement in both groups after training. Comparison of muscle strength improvement between the two groups showed a statistically significant improvement in the experimental group compared to the control group (p<0.05). SCIM III measurements showed significant improvement in the scores for Self-care and Transfer items in the experimental group. Conclusion: Motor imagery training was more effective than general muscle strengthening training in improving the residual upper extremity muscle strength and activities of daily living of patients with chronic cervical spinal cord injury.

• 대한의용생체공학회:의공학회지
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• 제43권6호
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• pp.375-381
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• 2022

Brain-computer interface (BCI) is a technology that allows users with motor disturbance to control machines by brainwaves without a physical controller. Motor imagery (MI)-BCI is one of the popular BCI techniques, but it needs a long calibration time for users to perform a mental task that causes high fatigue to the users. MI is reported as showing a similar neural mechanism as motor execution (ME) and motor observation (MO). However, integrative investigations of these three tasks are rarely conducted. In this study, we propose a new paradigm that incorporates three tasks (MI, ME, and MO) and conducted a comparative analysis. For this study, we collected Electroencephalograms (EEG) of motor imagery/execution/observation from 28 healthy subjects and investigated alpha event-related (de)synchronization (ERD/ERS) and classification accuracy (left vs. right motor tasks). As result, we observed ERD and ERS in MI, MO and ME although the timing is different across tasks. In addition, the MI showed strong ERD on the contralateral hemisphere, while the MO showed strong ERD on the ipsilateral side. In the classification analysis using a Riemannian geometry-based classifier, we obtained classification accuracies as MO (66.34%), MI (60.06%) and ME (58.57%). We conclude that there are similarities and differences in fundamental neural mechanisms across the three motor tasks and that these results could be used to advance the current MI-BCI further by incorporating data from ME and MO.

• 대한의용생체공학회:의공학회지
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• 제32권4호
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• pp.295-304
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• 2011

In this study, we evaluated the EEG based BCI algorithm using common spatial pattern to find realistic applicability using neurofeedback EEG based BCI algorithm - EEG mode, feature vector calculation, the number of selected channels, 3 types of classifier, window size is evaluated for 10 subjects. The experimental results have been evaluated depending on conditioned experiment whether neurofeedback is used or not In case of using neurofeedback, a few subjects presented exceptional but general tendency presented the performance improvement Through this study, we found a motivation of development for the specific classifier based BCI system and the assessment evaluation system. We proposed a need for an optimized algorithm applicable to the robust motor imagery evaluation system with more useful functionalities.

• 대한의용생체공학회:의공학회지
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• 제30권5호
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• pp.428-437
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• 2009

The Performance research about EEG-BCI algorithm in BCI-naive subjects is very important for evaluating the applicability to the public. We analyzed the result of the performance evaluation experiment about the EEG-BCI algorithm in BCI-naive subjects on three different aspects. The EEG-BCI algorithm used in this paper is composed of the common spatial pattern(CSP) and the least square linear classifier. CSP is used for obtaining the characteristic of event related desynchronization, and the least square linear classifier classifies the motor imagery EEG data of the left hand or right hand. The performance evaluation experiments about EEG-BCI algorithm is conducted for 40 men and women whose age are 23.87${\pm}$2.47. The performance evaluation about EEG-BCI algorithm in BCI-naive subjects is analyzed in terms of the accuracy, the relation between the information transfer rate and the accuracy, and the performance changes when the different types of cue were used in the training session and testing session. On the result of experiment, BCI-naive group has about 20% subjects whose accuracy exceed 0.7. And this results of the accuracy were not effected significantly by the types of cue. The Information transfer rate is in the inverse proportion to the accuracy. And the accuracy shows the severe deterioration when the motor imagery is less then 2 seconds.

• ETRI Journal
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• 제28권2호
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• pp.162-174
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• 2006

Several photogrammetric and geographic information system applications such as surface matching, object recognition, city modeling, environmental monitoring, and change detection deal with multiple versions of the same surface that have been derived from different sources and/or at different times. Surface registration is a necessary procedure prior to the manipulation of these 3D datasets. This need is also applicable in the field of medical imaging, where imaging modalities such as magnetic resonance imaging (MRI) can provide temporal 3D imagery for monitoring disease progression. This paper will present a general automated surface registration procedure that can establish correspondences between conjugate surface elements. Experimental results using light detection and ranging (LIDAR) and MRI data will verify the feasibility, robustness, and accuracy of this approach.