• Journal of KIISE:Computing Practices and Letters
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• v.10 no.1
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• pp.25-36
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• 2004

This paper proposes and measures the performance of a distributed EIT (Electrical Impedance Tomography) image reconstruction algorithm which has a master-slave structure. The image construction is a computation based application of which the execute time is proportional to the cube of the unknowns. After receiving a specific frame from the master, each computing node extracts the basic elements by executing the first iteration of Kalman Filter in parallel. Then the master merges the basic element lists into one group and then performs the sequential iterations with the reduced number of unknowns. Every computing node has MATLAB functions as well as extended library implemented for the exchange of MATLAB data structure. The master implements another libraries such as threaded multiplication, partitioned inverse, and fast Jacobian to improve the speed of the serial execution part. The parallel library reduces the reconstruction time of image visualization about by half, while the distributed grouping scheme further reduces by about 12 times for the given target object when there are 4 computing nodes.

• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.42-53
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• 2022

The clinical concept of coronary artery disease (CAD) has seen a paradigm shift over the last decade. CAD is mostly a progressive disease, and patients with CAD can develop acute coronary syndromes at any point in disease progression. In this clinical context, a new term, "chronic coronary syndrome," was published in the 2019 European Society of Cardiology guidelines, reflecting the importance of early diagnosis and active management. Recent advances have been made in the evaluation of CAD using coronary CT angiography (CCTA). The clinical usefulness of CCTA in patients with stable angina or chronic coronary syndrome begins with the detection of early asymptomatic CAD. The characterization of atherosclerotic plaque and its role in determining treatment strategies for CAD have been demonstrated for all stages of the disease. This review describes the pathophysiology of stable angina to aid in the understanding of the clinical applications of CCTA.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.469-474
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• 2005

Tn this study, the noll-destructive computed X-ray tomography was adopted to observe the density distribution of the needle-punched C-C composites nozzle throat. The density distribution of the C-C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of the C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

• Journal of Veterinary Clinics
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• v.31 no.5
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• pp.376-381
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• 2014

In this study, we analyzed the computed tomography (CT) measurements of lung volume and density in dogs with relation to body weight, age, sex, and breed. The multi-detector CT examination of the thorax was performed on dogs without respiratory or cardiovascular diseases. Three-dimensional reconstruction of CT images facilitated measurement of lung volume and density. There was a statistical significant correlation between body weight and lung volume (p < 0.0001). Lung density significantly decreased with an increase in body weight (p = 0.0078). However, no correlation was seen between these lung parameters and either sex or age of the dogs. In conclusion, this study shows that body weight is an important factor to consider when interpreting total lung volume and density values measured by quantitative CT. We highlight the need for further study using quantitative CT in identifying the potential effects of sex, age, and disease status on these parameters.

• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.138-148
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• 2022

Purpose This study evaluated the rates and annual trends of pediatric CT scans in South Korea using a nationwide population-based database. Materials and Methods Data regarding pediatric CT scan usage between 2012 and 2017 were retrieved from the health insurance review and assessment service. Data on the age, sex, diagnosis, and the anatomical area of involved patients were also extracted. Results A total of 576376 CT examinations were performed among 58527528 children aged below 18 years (9.8 scans/1000 children), and the number of CT examinations per 1000 children was noted to have increased by 23.2% from 9.0 in 2012 to 11.0 in 2017. Specifically, the number of CT examinations increased by 32.9% for the 6-12 years of age group (7.4/1000 to 9.8/1000) and by 34.0% for the 13-18 years of age group (11.4/1000 to 15.3/1000). Moreover, majority of the CT scans were limited to the head (39.1%), followed by the extremities (32.5%) and the abdomen (13.7%). Notably, the number of extremity CT scans increased by 83.6% (2.3/1000 to 4.2/1000), and its proportion as compared to other scans increased from 25.3% to 37.7%. Conclusion CT scans in the pediatric population increased continuously from 2012 to 2017 at an annual rate of 4.4%. Therefore, physicians should balance the benefits of CT with its potential harms from associated radiation exposure in pediatric patients.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3275-3284
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• 1998

In this paper, we deseribe a Medical Image Information System. Our system stores and manages 5 dimensional medical image data and provides the 3 dimensional medical data via the Internet. The Internet standard VR format. VRML(Virtual Reality Modeling Language) is used to represent the 3I) medical image data. The 3D images are reconstructed from medical image data which are enerated by medical imaging systems such ans CT(Computerized Tomography). MRI(Magnetic Resonance Imaging). PET(Positron Emission Tomograph), SPECT(Single Photon Emission Compated Tomography). We implemented the medical image information system shich rses a surface-based rendering method for the econstruction of 3D images from 2D medical image data. In order to reduce the size of image files to be transfered via the Internet. The system can reduce more than 50% for the triangles which represent the surfaces of the generated 3D medical images. When we compress the 3D image file, the size of the file can be redued more than 80%. The users can promptly retrieve 3D medical image data through the Internet and view the 3D medical images without a graphical acceleration card, because the images are represented in VRML. The image data are generated by various types of medical imaging systems such as CT, MRI, PET, and SPECT. Our system can display those different types of medical images in the 2D and the 3D formats. The patient information and the diagnostic information are also provided by the system. The system can be used to implement the "Tele medicaine" systems.

• Investigative Magnetic Resonance Imaging
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• v.16 no.2
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• pp.173-176
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• 2012

We report the radiological findings of regional enhancement of the liver adjacent to the right adrenal pheochromocytoma. CT and MRI showed focal strong enhancement of adjacent liver tissue in the arterial phase. However during the delayed phase, the lesion showed iso-attenuation with normal hepatic parenchyma and not delineated. The lesion did not show abnormal signal intensity on neither T1 nor T2 weighted images and indistinguishable from normal parenchyma. The enhancing hepatic lesion was spontaneously regressed on postoperative follow up CT which was taken several months after the adrenalectomy.

• Journal of IKEEE
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• v.20 no.3
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• pp.226-234
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• 2016

Electrical resistance tomography (ERT) is an imaging technique where the internal resistivity distribution inside an object is reconstructed. The ERT image reconstruction is a highly nonlinear ill-posed problem, so regularization methods are used to achieve desired image. The reconstruction outcome is dependent on the type of regularization method employed such as l2-norm, l1-norm, and total variation regularization method. That is, use of an appropriate regularization method considering the flow characteristics is necessary to attain good reconstruction performance. Therefore, in this paper, regularization methods are tested through numerical simulations with different flow conditions and the performance is compared.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1287-1291
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• 2021

Testicular lymphoma is an uncommon testicular tumor that usually presents as a painless mass. It usually shows hypervascularity on color Doppler ultrasound (US) and a mild enhancement on enhanced CT or MRI. We present an unusual case of a testicular lymphoma mimicking a missed testicular torsion in a 67-year-old male patient with right scrotal swelling and intermittent pain for 2 months. Color Doppler US demonstrated the absence of vascularity in the enlarged right testis, and the initial diagnosis was a missed testicular torsion. CT demonstrated a poorly enhancing mass rather than a missed testicular torsion with enhanced small nodular foci at the periphery. The final pathological diagnosis was testicular lymphoma.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.414-418
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• 2006

유비쿼터스 컴퓨팅의 인프라가 되는 센서 네트워크는 매우 작은 하드웨어로 이루어지는 많은 수의 센서 노드들로 구성된다. 이 네트워크의 토폴로지와 라우팅 방식은 그 목적에 따라 결정되어야 하며, 하드웨어 및 소프트웨어도 필요한 경우에는 변경되어야 한다. 따라서 그러한 네트워크를 최적으로 설계하기 위해서는 시스템 동작을 확인하고 성능을 예측할 수 있는 센서 네트워크 시뮬레이터가 필요하다. 현존하는 몇몇 센서 네트워크 시뮬레이터들은 특정 하드웨어나 운영체제에 맞추어 개발되었기 때문에, 그러한 특정 시스템들을 위해서만 사용될 수 있다. 그리고 시스템 설계 상의 주요 이슈가 되는 전력 소모량 및 프로그램 실행 시간을 추정하기 위한 어떤 수단도 지원하지 못하고 있다. 이 연구에서는 기존의 센서 네트워크 시뮬레이터들이 갖고 있는 문제점을 해결한 시뮬레이터를 개발하고, 센서 네트워크의 계층적 라우팅 프로토콜인 LEACH, TEEN, APTEEN의 전력소모량을 시뮬레이션을 이용하여 분석하였다. 시뮬레이션의 작업부하인 명령어 트레이스로는 ATmega128L 마이크로컨트롤러용 크로스컴파일러에 의해 생성된 실행 이미지를 사용하였다. 따라서 각각의 라우팅 프로토콜을 실제 센서 보드에서 동작하는 응용 프로그램으로 구현하고, 컴파일된 실행 이미지를 작업부하로 사용하여 시뮬레이션 하였다. 라우팅 프로그램들은 ETRI의 센서 네트워크 운영체제인 Nano-Q+ 1.6.1을 기반으로 구현되었으며, 하드웨어 플랫폼은 옥타컴의 센서 보드인 Nano-24이다. 시뮬레이션 결과에 따르면, 센서 네트워크는 그 사용 목적에 따라 라우팅 프로토콜을 적절히 선택해야 한다는 것을 알 수 있다. 즉, LEACH는 주기적으로 네트워크의 상황을 체크해야 하는 경우에 적합하고, TEEN은 환경의 변화를 수시로 감지해야 하는 경우에 적합하다. 그리고 APTEEN은 전력소모량과 기능 측면을 모두 고려할 때 가장 효과적인 라우팅 프로토콜이라고 할 수 있다.iRNA 상의 의존관계를 분석할 수 있었다.수안보 등 지역에서 나타난다 이러한 이상대 주변에는 대개 온천이 발달되어 있었거나 새로 개발되어 있는 곳이다. 온천에 이용하고 있는 시추공의 자료는 배제하였으나 온천이응으로 직접적으로 영향을 받지 않은 시추공의 자료는 사용하였다 이러한 온천 주변 지역이라 하더라도 실제는 온천의 pumping 으로 인한 대류현상으로 주변 일대의 온도를 올려놓았기 때문에 비교적 높은 지열류량 값을 보인다. 한편 한반도 남동부 일대는 이번 추가된 자료에 의해 새로운 지열류량 분포 변화가 나타났다 강원 북부 오색온천지역 부근에서 높은 지열류량 분포를 보이며 또한 우리나라 대단층 중의 하나인 양산단층과 같은 방향으로 발달한 밀양단층, 모량단층, 동래단층 등 주변부로 NNE-SSW 방향의 지열류량 이상대가 발달한다. 이것으로 볼 때 지열류량은 지질구조와 무관하지 않음을 파악할 수 있다. 특히 이러한 단층대 주변은 지열수의 순환이 깊은 심도까지 가능하므로 이러한 대류현상으로 지표부근까지 높은 지온 전달이 되어 나타나는 것으로 판단된다.의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{99m}Tc$-transierrin이 감염 병소의 영상진단에 사용될 수 있을 것으로 기대된다.리를 정량화 하였다. 특히 선조체에서의 도파민 유리에 의한 수용체 결합능의 감소는 흡연에 의한 혈중 니코틴의 축적 농도와 양의 상관관계를 보였다(rho=0.9, p=0.04). 결론: $[^{11}C]raclopride$ PET을 이용하여 비흡연 정상인에서 흡연에 의한 도파민 유리를 영상화 및 정량화 하였고, 흡연에 의한 선조체내 도파민 유리는 흡연시 흡수된