• Investigative Magnetic Resonance Imaging
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• 제9권2호
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• pp.117-133
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• 2005

자기공명영상에서 병리구조물을 깨닫기 위해서는 먼저 자기공명영상에서 정상 해부구조물을 깨달아야 한다. 자기공명영상에서 해부구조물을 익히기 위해서는 다음과 같은 학습 자료가 필요하다. 첫째, 온몸의 자기공명영상, 둘째, 수평, 이마 그리고 마루 자기공명영상, 셋째, 자기공명영상에 들어맞는 구역화영상, 넷째, 자기공명영상에 있는 해부구조물의 3차원영상, 넷째, 자기공명영상, 구역화영상 그리고 3차원영상을 볼 수 있는 소프트웨어가 필요하다. 그러나 지금까지 이러한 학습 자료를 구하기 힘들었다. 따라서 이 연구에서는 의과대학 학생과 의사가 자기공명영상에서 정상 해부구조물을 익히는 데 도움을 주는 학습 자료를 다음처럼 만들었다. 표준 체형을 가진 건강한 한국인 남성을 골랐다. 온몸의 자기공명영상 613장을 찍고(slice thickness 3 mm, interslice gap 0 mm, field of view 480mm${\times}$480mm, resolution 512${\times}$512, T1 weighted) 개인용 컴퓨터에 옮겼다. 자기공명영상에 있는 60개의 해부구조물을 구역화해서 구역화영상을 만들었다. 이마, 마루 자기공명영상과 이마, 마루 구역화영상을 만들었다. 구역화영상을 바탕으로 47개 해부구조물의 3차원영상을 수동 표면재구성 방법으로 만들었다. 자기공명영상, 구역화영상, 3차원영상을 볼 수 있는 소프트웨어를 만들었다. 이 연구에서 만든 온몸의 수평, 이마, 마루 자기공명영상, 자기공명영상에 들어맞는 구역화영상, 3차원영상, 소프트웨어와 같은 학습 자료는 의과대학 학생과 의사가 자기공명영상에서 정상 해부구조물을 익히는 데 도움을 줄 것이다. 이 학습 자료는 인터넷이나 CD를 통해서 널리 퍼뜨릴 것이다.

• 전자공학회지
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• 제22권8호
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• pp.33-43
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• 1995

생산시스템 분야에서의 다중로봇시스템에 대한 필요성이 증가되고 있기 때문에, 이에 대한 시스템 성능분석이 우선적으로 필요하다. 본 논문에서는 다중로봇시스템의 성능평가를 위한 컴퓨터 시뮬레이션 방법을 제시한다. 먼저 오류회복 기능만을 고려한 다중로봇시스템에 대하여 여러 가지의 모델링 방법 중에서 확장 페트리 네트 모델을 기초로 하여 컴퓨터 시뮬레이션 하는 과정을 제시하고 제시된 시뮬레이션 방법의 유효성을 입증하기 위하여 부가적으로 큐잉모델을 기초로 한 해석적 수식을 유도하여 두 가지의 결과를 비교해 본다. 그 다음, 오류회복 기능에 덧붙여서 충돌회피 기능을 고려한 다중로봇시스템은 해석적 수식을 유도하기 위해서는 강력한 가정들이 필요하며 이러한 가정들 때문에 실제 시스템을 정확히 모델에 반영하기 어려워진다. 따라서, 그 유효성이 입증된 컴퓨터 시뮬레이션을 이용하면 필요한 최적의 운용 변수를 용이하게 선택할 수 있을 것이다. Since there are Increasing demands for multirobot interconnection systems(MRIS) in Industrial manufacturing system, the performance evaluation of the MRIS is first needed. This thesis presents a computer simulation technique for the performance evaluation of the MRIS. First, we consider a error recoverable MRIS. We adopt the extended Petri net model as a computer simulation model that allows an easy evaluation of the performance. To verify the significance of the proposed computer simulation method, mathematical analysis, which is based on the given queueing model, is carried out with some design issues for the MRIS. In addition to this, it is required to analyze the MRIS considering collision avoidance as well as error recovery. In this case, methematial analysis needs hard assumptions which are the constraints for the precise description of real environment. Thus, we present a computer simulation model and its results suggest an optimal operational strategy for the MRIS under given conditions.

• Investigative Magnetic Resonance Imaging
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• 제20권4호
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• pp.224-230
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• 2016

Purpose: The purpose of this study was to compare the grade of fatty degeneration and atrophy of rotator cuffs on immediate postoperative MRI to those on preoperative MRI in patients with rotator cuff tears. Materials and Methods: Seventy patients were included in this study, who received arthroscopic rotator-cuff repair and underwent both preoperative magnetic resonance imaging (MRI) and immediate postoperative MRI in our institution. Fatty degeneration of rotator cuffs and the atrophy of supraspinatus muscles were evaluated with T1 oblique sagittal images in the Y-shaped view. Fatty degeneration was evaluated using a Goutallier classification system, and the atrophy of supraspinatus muscles was evaluated using a modified tangent sign and a visual occupation ratio. Results: From 70 patients, a total of 100 tendons were repaired: 18, 69, and 13 tendons were treated for subscapularis, supraspinatus, and infraspinatus, respectively. The Goutallier grades (P = 0.012), modified tangent signs (P = 0.000), and visual occupation ratios (P = 0.000) of supraspinatus muscles were significantly decreased in immediate postoperative MRIs when compared to preoperative MRIs. In immediate postoperative MRIs, the Goutallier grades of supraspinatus muscles were decreased by one grade in 18.8% (n = 13) of the patients, and the atrophy of supraspinatus muscles was improved by one grade in 26.1% (n = 18) for modified tangent signs and 21.7% (n = 15) for visual occupation ratios. However, fatty infiltration by the Goutallier grades of subscapularis (P = 1.000) and infraspinatus (P = 0.157) muscles were not significantly changed after arthroscopic surgery. Conclusion: Immediate postoperative MRIs showed a significant improvement of fatty degeneration and muscle atrophy in supraspinatus muscles when compared to preoperative MRIs.

• ETRI Journal
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• 제31권2호
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• pp.237-239
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• 2009

A whole-body voxel model of a 7-year-old male volunteer was developed from 384 axial magnetic resonance images (MRIs). The MRIs were acquired with intervals of 3 mm for the entire body in a body coil. In order to reduce the MRI acquisition time for the child, the repetition and echo times under T1 weighted image were chosen to be 566 ms and 8 ms, respectively. The MRIs were classified according to 30 types of tissues with known electrical parameters. The developed voxel model was adjusted to the physical average of 7-year-old Korean boys. The body weight of the adjusted model, calculated with the mass tissue densities, is within a 6% difference from the 50th percentile weight.

• 한국정보시스템학회:학술대회논문집
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• 한국정보시스템학회 1997년도 추계학술대회논문집 기업경쟁력 향상을 위한 정보통신 기술의 활용
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• pp.437-443
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• 1997

객체를 기반으로 하는 소프트웨어 부품의 재사용은 개별 부품의 효율적 관리와 이 것의 적절한 조합을 통해 소프트웨어 생산성을 극대화한다. 이를 위해서는 클래스 라이브러 리 화에 의한 명확한 식별과 분류, 정제, 저장으로 사용자 요구에 맞는 부품을 쉽게 검색할 수 있으며 새로운 부품의 수정과 합성이 가능한 재사용 시스템이 요구된다. 따라서 본 논문 에서는 객체지향을 기반의 소프트웨어 개발에 있어 브라우징 기법을 적용하여 사용자 요구 에 맞도록 재사용 부품들을 분류, 저장, 검색하여 재상용 할뿐더러 검색된 클래스가 사용자 의 요구에 맞도록 수정-합성 과정을 통해 재사용 가능하게 하는 다중 뷰 재사용 통합 시스 템인 MRIS (Multi-View Reuse Integrated System)를 구현하였다.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.10-17
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• 2018

Purpose: To evaluate interpretation errors involving spine MRIs by residents in their second to fourth year of training, classified as minor, intermediate and major discrepancies, as well as the types of commonly discordant lesions with or without clinical significance. Materials and Methods: A staff radiologist evaluated both preliminary and final reports of 582 spine MRIs performed in the emergency room from March 2011 to February 2013, involving (1) the incidence of report discrepancy, classified as minor if there was sufficient description of the main MR findings without ancillary or incidental lesions not influencing the main diagnosis, treatment, or patients' clinical course; intermediate if the correct diagnosis was made with insufficient or inadequate explanation, potentially influencing treatment or clinical course; and major if the discrepancy affected the main diagnosis; and (2) the common causes of discrepancy. We analyzed the differences in the incidence of discrepancy with respect to the training years of residents, age and sex of patients. Results: Interpretation discrepancy occurred in 229 of the 582 cases (229/582, 39.3%), including 146 minor (146/582, 25.1%), 40 intermediate (40/582, 6.9%), and 43 major cases (43/582, 7.4%). The common causes of major discrepancy were: over-diagnosis of fracture (n = 10), missed cord lesion (n = 9), missed signal abnormalities associated with diffuse marrow (n = 5), and failure to provide differential diagnosis of focal abnormal marrow signal intensity (n = 5). No significant difference was found in the incidence of minor, intermediate, and major discrepancies according to the levels of residency, patients' age or sex. Conclusion: A 7.4% rate of major discrepancies was found in preliminary reporting of emergency MRIs of spine interpreted by radiology residents, probably related to a relative lack of clinical experience, indicating the need for additional training, especially involving spine trauma, spinal cord and bone marrow lesions.

• Wind and Structures
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• 제21권5호
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• pp.489-503
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• 2015

This paper surveys and complements contributions by the National Institute of Standards and Technology to techniques ensuring that the wind tunnel procedure for the design of high-rise structures is based on sound methods and allows unambiguous inter-laboratory comparisons. Developments that enabled substantial advances in these techniques include: Instrumentation for simultaneously measuring pressures at multiple taps; time-domain analysis methods for estimating directional dynamic effects; creation of large simulated extreme directional wind speed data sets; non-parametric methods for estimating mean recurrence intervals (MRIs) of Demand-to-Capacity Indexes (DCIs); and member sizing based on peak DCIs with specified MRIs. To implement these advances changes are needed in the traditional division of tasks between wind and structural engineers. Wind engineers should provide large sets of directional wind speeds, pressure coefficient time series, and estimates of uncertainties in wind speeds and pressure coefficients. Structural engineers should perform the dynamic analyses, estimates of MRIs of wind effects, sensitivity studies, and iterative sizing of structural members. The procedure is transparent, eliminates guesswork inherent in frequency domain methods and due to the lack of pressure measurements, and enables structural engineers to be in full control of the structural design for wind.

• Imaging Science in Dentistry
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• 제42권1호
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• pp.13-18
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• 2012

Purpose : The aim of this study was to investigate the effect of the autologous blood injection (ABI) for chronic recurrent temporomandibular joint (TMJ) dislocation using magnetic resonance imaging (MRI). Materials and Methods : ABI was applied to 14 patients who had chronic recurrent TMJ dislocation. MRIs of the patients were taken and compared before and one month after the injection. Results : All of the patients had no dislocations of their TMJs on clinical examination one month after the injection. In the pre-injection, unilateral or bilateral TMJ dislocations were observed on MRIs in all patients. One month after the injection, TMJ dislocations were not observed in MRI evaluation of any patients. A significant structural change that caused by ABI was not observed. Conclusion : The procedure was easy to perform and it caused no foreign body reaction. However, it was unclear how the procedure prevented the dislocation.

• 대한족부족관절학회지
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• 제7권1호
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• pp.131-134
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• 2003

Most interdigital neuroma can be diagnosed clinically. But, diagnostic local injection method, sonography and magnetic resonance image(MRI) have been used as secondary tests for clinical confirmation or surgery. Recently, there have been active discussions on the method of interdigital neuroma diagnosis for which sonography or MRI is used. For finding out the location or the number of interdigital neuroma particularly in non-typical clinical manifestation or surgery, MRIs, which are exellent in tissue contrast, may be quite helpful. This case had an interdigital neuroma showing non-typical manifestation. MRIs were used for clinical diagnostic confirmation and finding out the location and the number of interdigital neuroma. Thus, the validity along with literary consideration is being reported.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2000년도 동계총회 및 제16회 자기공명 학술발표회
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• pp.44-46
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• 2000