• Progress in Medical Physics
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• v.24 no.1
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• pp.1-24
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• 2013

As image-guided radiation therapy (IGRT) has been commonly used for more accurate patient setup and monitoring tumor movement during radiation therapy, the necessity for management of imaging dose is increased. However, it has not been an interest issue to radiation therapy communities because the imaging dose is much lower than the therapeutic dose. However, since the cumulative dose from 4DCT and repeated imaging for daily setup verificationin would not be ignorable, appropriate dose management based on ALARA (As Low As Reasonably Achievable) principle is required. In this study, we aimed that (1) survey on imaging equipments and modalities used for IGRT, (2) estimation of IGRT imaging dose depending on treatment types and equipments, (3) collecting data of effective dose on treatment sites from each equipment and imaging protocol, and thus finally provide guideline for imaging dose reduction and optimization.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.1
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• pp.1-10
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• 2010

Purpose: The effect of artifact was analyzed, which occurs from fiducial marker during the liver Image Guided Radiation Therapy (IGRT) using the fiducial marker. Materials and Methods: The size of artifact of fixed fiducial marker and length of mobile fiducial marker locus were measured using the On-Board Imager system (OBI) and CT simulator, and 2D-2D matching and 3D-3D matching were carried out, respectively, and at this time, the coordinates transition value of couch was analyzed. Results: The measurement of fixed fiducial marker artifact size indicated CT 4.90, 8.10, 12.90, 19.70 mm and OBI 5.60, 10.60, 14.70, 29.40 mm based on the reference CT slice thickness of 1.25, 2.50, 5.00, and 10.00 mm. Meanwhile, the measurement of mobile fiducial marker locus length indicated CT 42.00, 43.10, 46.50 mm, and OBI 43.40, 46.00, 49.30 mm. The coordinates transition of 1.00, 2.00, and 8.00 mm occurred between 2D-2D matching and 3D-3D matching. Conclusion: It was confirmed that the therapy error increased during IGRT due to the influence of artifact when CT slice thickness increased. Thus, it may be desirable to acquire the image less than 2.50 mm in slice thickness when IGRT is implemented using the fiducial marker.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.144-144
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• 2012

하천 제방의 안정성을 평가하기 위해서는 홍수시 제방 주변의 흐름특성을 분석하는 것이 필요하다. 일반적으로 홍수시 유속은 측정된 홍수량을 이용한 단면평균유속을 이용하여 평가를 하고 있기 때문에 제방 주변의 흐름특성을 정확하게 분석하는데 한계가 있다. 이를 개선하기 위해서는 홍수시 제방 주변의 유속을 측정하여야 하는데 접근이 어렵고 위험하기 때문에 봉부자 또는 유속계를 이용한 유속측정이 어려운 실정이다. 이와 같은 경우 제방 주변의 영상 분석을 이용한 표면영상유속계의 활용이 좋은 대안이 될 수 있다. 표면영상유속계의 경우 원거리에서도 줌을 이용하여 영상을 획득할 수 있고, 측정 시간이 짧기 때문에 제방 주변의 유속을 간편하게 측정 가능하다. 하지만 표면영상유속계(SIV)는 영상좌표와 물리좌표 사이의 좌표 변환을 필요로 한다. 종전까지는 일반적으로 8-변수 좌표 변환법이 널리 이용되었으나, 이 방법은 최소한 4점 이상의 참조점이 필요하기 때문에 수면위에 참조점을 설치해야 하는 어려움이 있다. 또한, 내삽을 하는 방법이기 때문에 참조점 내부의 점에 대해서는 비교적 정확한 변환이 가능하지만, 참조점 외부의 좌표들에 대해서는 부정확한 변환이 되는 단점이 있었다. 따라서 본 연구에서는 카메라 모형을 이용하여, 새로운 좌표 변환식을 유도하였다. 이 영상좌표 변환식은 참조점을 이용하지 않으며, 수면과 카메라간의 연직 거리와 카메라의 기울어진 각도만을 이용하여 좌표 변환이 가능한 방법이다. 참조점을 필요로 하지 않기 때문에 측량의 번거로움이 없으며, 변환식내에서 내삽을 하지 않기 때문에 영상 전체에 대해 고른 좌표 변환이 가능한 장점을 지니고 있다.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2603-2605
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• 2004

적외선 영상 시뮬레이션 시스템(IIRSS : Imaging Infrared Simulation System)은 적외선 영상 센서를 탑재한 유도무기체계의 종말 호밍 단계에서의 체계 유도조종 성능 및 기능을 시험평가하기 위한 목적으로 연구 개발되었다. 적외선 영상 시뮬레이션 시스템은 체계성능을 단계적이고 종합적인 시험평가를 위하여 표적 주위 환경에 대하여 사실적이고, 동적인 실시간 시뮬레이션 환경이 제공되어야한다. 시뮬레이터 개발에 있어서 주요 관련 기술은 지형, 지물에 대한 3차원 모델링, 대기투과효과 모델링 및 합성된 적외선 영상의 실시간 렌더링 기술 등이다. 본 논문에서는 적외선 센서 시뮬레이션의 방법으로써 HILS(Hardware-in-The-Loop Simulation)를 위한 시뮬레이터 구성, 적외선 영상 생성을 위한 도구와 절차 및 시뮬레이션 방안에 대하여 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.907-914
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• 1997

The conventional decoding procedure for the images encoded using fractal contractive transformation algorithms is performed by applying the transformations iteratively for an arbirary initial image. In this paper, we showed that the atractor image can be obtained analytically when the image is encoded using the fractal algorithm proposed by Monro and Dudbridge, in which the corresponding domain block for a range block is fixed. Using the analytical formula, we can obtain the attractor image without iteration procedure. Computer simulation results for various test images show that we can increase the image decoding speed by more than five times when we use the analytical formula compared to the previous iteration methods. Also we confirmed that the real time decoding by software on PD is possible for the moving picture with QCIF formats.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1233-1243
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• 2023

Percutaneous ultrasound-guided biopsy is useful for the pathologic confirmation of variable body lesions to establish diagnostic and therapeutic approaches. However, deep pelvic lesions are a challenge for pathologic diagnoses because of the presence of the bowel, bladder, major vessels, and pelvic bones which make a percutaneous approach difficult and dangerous. In female, the vagina is elastic and near the pelvic internal organs. Therefore, transvaginal ultrasound may serve as an effective and safe guide for the pathologic diagnosis of pelvis lesions. This review aimed to introduce the indications for, and the method of transvaginal ultrasoundguided biopsy, and to describe the reported diagnostic accuracy and safety.

• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.339-346
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• 2003

MRI provides anatomical structure information with superb spatial resolution that can be utilized in clinical surgeries. Advanced image processing techniques in conjunction with the MRI-guided surgery is expected to be of great importance in brain surgeries in the near future. In this paper, we introduce an image-guided surgery technique using the stereo matching method. To perform image-guided biopsy operations, we made MRI markers, camera markers and a detection probe marker. To evaluate the accuracy of the image-guided system. we made a silicone phantom. Using the phantom and markers, we have performed MRI-guided experiments with a 1.5 Tesla MRI system. It has been verified from phantom experiments that our system has a positioning error less than 1.5%. Compared with other image guided surgery system, our system shows better positioning accuracy.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.12
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• pp.947-954
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• 2017

In case of a fire in urban large structures such as super high-rise buildings, evacuation guidance must be provided to the occupants in order to minimize human deaths and injuries. Therefore, it is essential to provide emergency evacuation guidance when a major fire occurs. In order to effectively support evacuation guidance, it is important to identify major items such as fire location, occupant position, escape route, etc. Also, it is important to quickly identify evacuation areas where residents can safely evacuate from a fire. In this paper, we analyze the CCTV video and propose a method of measuring visibility of the evacuation zone from the smoke caused by the fire in order to determine the safety of evacuation area. To do this, we first extract the background video from the smoke video to measure the visibility of the specific area due to smoke. After generating an edge-extracted image for the extracted background video, the degree of visibility is measured by calculating the change in the edge strength due to smoke.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.256-264
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• 2012

The directional algebraic reconstruction technique (DART) using the trigonometric current pattern is one of the image reconstruction algorithms in electrical impedance tomography (EIT). This method needs to compute resistances between electrode pairs as using relation between the injected currents and measured voltages for the reconstruction of the inner image. The delay time is incurred in this process. Therefore this paper proposes modified directional algebraic reconstruction technique (mDART) using the adjacent current pattern instead of the trigonometric current pattern to solve the delay time for initial resistance values. The proposed method uses measured voltages instead of computed resistances in the reconstruction algorithm. Hence this method can eliminate the delay time because it does not use the resistances. In conclusion, the proposed method improves image quality and image reconstruction time by using the adjacent current pattern. To prove performance of the proposed method, we carried on computer simulation of various cases.

• Physical Therapy Korea
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• v.8 no.4
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• pp.91-99
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• 2001

뇌 손상 후 급성기에 기능의 자발적인 회복이 일어나지만 환자들은 환측의 상지를 잘 사용하지 못하게 된다. 그 결과 원하는 움직임을 억제하는 상황을 발생시키는데 이것을 학습 무사용 증후군(learned nonu se syndrome)이라 한다. 이러한 학습 무사용 증후군을 치료하기 위해 억제-유도 치료(constraint-induced therapy)가 고안되었다. 억제-유도 치료는 연속되는 몇 주간에 걸쳐 매일 많은 시간 동안 건측의 상지를 묶어두고 환측 상지를 사용하게 하여 기능을 반복 학습하게 함으로써 기능을 증진시키는 방법이다. 이미 여러 연구자들이 경두개 자기자극(transcranial magnetic stimulation), 움직임 관련 피질전위(movement-related cortical potential), 기능적 자기공명 영상기법(functional magnetic resonance imaging) 등을 통하여 억제-유도 치료 후 운동피질영역에서의 재조직화를 보고함으로써 기능 증진과 관련된 회복 기전을 뒷받침하고 있다. 억제-유도 치료의 영역은 확대되어 뇌졸중, 척수손상, 고관절 치환술 후로 하지에서의 기능증진을 위하여 연구가 진행되고 있으며 특히 뇌졸중 후 실어증 환자에서 새로운 방법으로 제시되고 있다. 따라서, 억제-유도 치료는 신경학적인 손상 후 움직임의 재활에 있어서 치료-유도를 통한 중추신경계의 회복에 효과적으로 작용할 수 있다.