• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.794_795
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• 2009

This paper presents an analysis method for a permanent magnet excited Transverse Flux Linear Motor (TFLM) with spiral core in a mover. The spiral core is used as mover core in order to make 3-dimensional magnetic flux path at the TFLM which has 3-dimensional magnetic flux flow. Magnetic field is analyzed by three-dimensional Equivalent Magnetic Circuit Network (EMCN) method. And an imaginary part, 'flux barrier,' is introduced to consider the spiral core characteristic. The computed thrust forces is compared to the measured results to show the effect of presented analysis method.

• 대한의용생체공학회:의공학회지
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• 제19권3호
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• pp.243-250
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• 1998

초고속 자기공명 영상 기법의 일종인 나선 주사 영상의 재구성을 위하여 k-공간에서 극좌표와 직각 좌표계를 기초로한 재구성방법들을 분석하였다. 나선 주사 영상의 재구성은 나선 궤적상에서 측정된 데이터를 극좌표나 직각 좌표계로 변환시키기 위하여 보간 기술들이 사용된다. 나선주사 영상의 다양한 재구성 알고리즘들을 시험하여 보았고, 재구성된 영상의 질을 비교하였다. 본 연구진이 제안한 투영 영역에서 dc-offset보정을 한 향상된 재구성 알고리즘이 시뮬레이션을 통하여 가장 우수한 것으로 나타났다. 또한, 기존의 재구성 방법들에서 나타났던 영상 artifact도 제안된 방법에서는 완전히 사라짐을 확인할 수 있었다.

• Investigative Magnetic Resonance Imaging
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• 제1권1호
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• pp.154-161
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• 1997

목적: 횡격막 파열은 그 진단이 어렵고 지연되는 경우가 많으며, 진단이 늦어지면 유병율과 사망율이 높아지므로 조기진다는 매우 중요하다. 저자들은 최근 많이 이용되는 영상진단법인 나선형 CT와 자기공명영상, 그리고 초음파건사중 어떤 방법이 가장 예민하고 정확한 진단방법인지 동물실험 모델을 통하여 평가하고자 하였다. 대상 및 방법: 토끼에서 인위적으로 횡격막파열을 대, 중, 소로 만든 후 1일, 3일, 7일째 나선형 CT와 자기공명영상, 그리고 초음파검사를 동시에 시행하였다. 결과: 횡격막파열의 진단 민감도와 특이도는 초음파검사가 94.4%와 92.9%, 자기 공명영상이 54.0%와 85.75, 나선형 CT가 46.0%와 78.6%이었다. 횡격막 파열의 진단은 초음파검사, 자기공명영상, 나선형 CT순으로 정확하였으며 초음파 검사가 자기공명영상이나 나선형 CT보다 유의하게 우월하였고(P<0.05), 자기공명영상과 나선형 CT는 유의한 차이가 없었다. 초음파검사는 파열의 크기와 상관없이 횡격막파열의 구별이 용이하였고 자기공명영상과 나선형 CT는 파열의 크기가 클수록 횡격막파열의 구별이 용이하였으나 통계적으로 유의한 차이는 없었다(P>0.05). 수술후 1일에는 전예에서 늑막삼출액이나 혈흉을 동반하였다. 이때에는 초음파나 자기공명영상이 나선형 CT에 비해 우월하였다. 시간경과에 따랄 초음파검사와 자기공명영상은 진단율이 상대적으로 저하되었으나 통게적으로 유의한 차이는 없었다(P>0.05) 탈장을 동반한 경우에는 진단의 민감도가 자기공명영상, 나선형 CT, 초음파검사순으로 높았으며 초음파검사가 상대적으로 낮았다. 그러나 통계적으로 유의한 차이는 없었다(P>0.05). 결론: 초음파검사가 횡격막파열의 진단에 가장 유용한 것으로 밝혀졌으며, 이러한 결과는 앞으로 임상에 적용하여 검증되어야 할 필요가 있다고 생각된다.

• Journal of Yeungnam Medical Science
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• 제31권2호
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• pp.109-112
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• 2014

A pulmonary artery sling is a very rare congenital abnormality in which the left pulmonary artery rises from the posterior surface of the right pulmonary artery and then passes between the trachea and the esophagus, causing tracheal compression. It is associated with tracheo-bronchial abnormalities (50%) and cardiovascular abnormalities (30%). It may produce respiratory symptoms through the airway compression of the abnormal left pulmonary artery and congenital abnormalities associated with it. Because most (90%) pulmonary artery sling patients present symptoms during infancy, their condition is often diagnosed in the first year of life. However, a pulmonary artery sling is occasionally found in adults. It is usually asymptomatic and found incidentally. This is a very rare case of an asymptomatic pulmonary artery sling in an adult. A 38-year-old man presented symptoms of mild exertional dyspnea. His spiral computed tomography showed a pulmonary artery sling. He was discharged without specific treatment because his symptoms improved without specific treatment and might not have been associated with a pulmonary artery sling. We report an adult case of an asymptomatic pulmonary artery sling diagnosed via spiral computed tomography, accompanied by a literature review.

• Korean Journal of Radiology
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• 제1권3호
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• pp.135-141
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• 2000

Objective: To compare the clinical utility of the different imaging techniques used for the evaluation of tracheobronchial diseases. Materials and Methods: Forty-one patients with tracheobronchial diseases [tuberculosis (n = 18), bronchogenic carcinoma (n = 10), congenital abnormality (n = 3), post-operative stenosis (n = 2), and others (n = 8)] underwent chest radiography and spiral CT. Two sets of scan data were obtained: one from routine thick-section axial images and the other from thin-section axial images. Multiplanar reconstruction (MPR) and shaded surface display (SSD) images were obtained from thin-section data. Applying a 5-point scale, two observers compared chest radiography, routine CT, thin-section spiral CT, MPR and SSD imaging with regard to the detection, localization, extent, and characterization of a lesion, information on its relationship with adjacent structures, and overall information. Results: SSD images were the most informative with regard to the detection (3.95±0.31), localization (3.95±0.22) and extent of a lesion (3.85±0.42), and overall information (3.83±0.44), while thin-section spiral CT scans provided most information regarding its relationship with adjacent structures (3.56±0.50) and characterization of the lesion (3.51±0.61). Conclusion: SSD images and thin-section spiral CT scans can provide valuable information for the evaluation of tracheobronchial disease.

• Imaging Science in Dentistry
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• 제43권2호
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• pp.63-69
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• 2013

After over one decade development, cone beam computed tomography (CBCT) has been widely accepted for clinical application in almost every field of dentistry. Meanwhile, the radiation dose of CBCT to patient has also caused broad concern. According to the literature, the effective radiation doses of CBCTs in nowadays market fall into a considerably wide range that is from $19{\mu}Sv$ to $1073{\mu}Sv$ and closely related to the imaging detector, field of view, and voxel sizes used for scanning. To deeply understand the potential risk from CBCT, this report also reviewed the effective doses from literatures on intra-oral radiograph, panoramic radiograph, lateral and posteroanterior cephalometric radiograph, multi-slice CT, and so on. The protection effect of thyroid collar and leaded glasses were also reviewed.

• 한국임상수의학회지
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• 제20권4호
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• pp.519-522
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• 2003

An appearance of herniated intervertebral disc into thoracolumbar vertebral canal was evaluated in two patients using computed tomography (CT). Before CT scanning, plain radiography and myelography were performed in both cases. CT images were compared to those of myelography. Dogs were positioned in sternal recumbency under inhalation anesthesia and transverse slices with 2 mm thickness were obtained around thoracolumbar region. The transverse CT images were examined using both vertebral and spiral window mode. The most common findings on CT images were loss of vertebral canal epidural fat, bulging of vertebral canal disc margins, displacement of spinal cord and flatted vertebral canal. Whereas, narrowed intervertebral disc space and simple extradural pattern were the main findings on plain and contrast radiographs. CT imges showed the extent of the herniated disc lesion, type II intervertebral disc hernation, and the displacement of spinal cord in detail in both occations. It is considered that degree and precise localization of the intervertebral disc herniation and subtle lesion of spinal cord could be identified accurately using computed tomography.

• Imaging Science in Dentistry
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• 제37권4호
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• pp.191-195
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• 2007

Purpose: To study the intra- and interobserver agreement of multidetector row computed tomography (MDCT) in interpretation of degenerative changes of the mandibular condyle. Materials and Methods: Five observers independently evaluated one hundred temporomandibular joint MDCT images for signs of osteophytes, erosion, sclerosis and flattening. The intra- and interobserver agreements were calculated by using Kappa statistics. Results: The intraobserver agreement was substantial for erosion (k=0.75), flattening (k=0.74) and sclerosis (k=0.72) and almost perfect for osteophytes (k=0.84). The interobserver agreement was fair for flattening (k=0.39), moderate for erosion (k=0.58) and sclerosis (k=0.48) and substantial for osteophytes (k=0.75). Conclusion: This study shows that we can expect good agreement for the presence of osteophytes, but not for flattening in the interpretation of MDCT images of the condyle.

• Imaging Science in Dentistry
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• 제44권3호
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• pp.177-183
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• 2014

Recent research in endodontics has highlighted the need for three-dimensional imaging in the clinical arena as well as in research. Three-dimensional imaging using computed tomography (CT) has been used in endodontics over the past decade. Three types of CT scans have been studied in endodontics, namely cone-beam CT, spiral CT, and peripheral quantitative CT. Contemporary endodontics places an emphasis on the use of cone-beam CT for an accurate diagnosis of parameters that cannot be visualized on a two-dimensional image. This review discusses the role of CT in endodontics, pertaining to its importance in the diagnosis of root canal anatomy, detection of periradicular lesions, diagnosis of trauma and resorption, presurgical assessment, and evaluation of the treatment outcome.

• 한국전산유체공학회지
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• 제16권1호
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• pp.90-95
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• 2011

The Navier-Stokes equations are solved to study the flow characteristics of a micro viscous pump. The viscous micropump is consisted of a stationary disk with a spiral shaped channel and a rotating disk. A simple geometrical model for the tip clearance is proposed and validated by comparing computed flow rate with corresponding experimental data. Present numerical solutions show satisfactory agreement with the corresponding experimental data. The tip clearance effect is found to become significant as the rotational speed increases. As the pressure load increases, a reversed flow region is seen to form near the stationary disk. The height of the channel is shown to be optimized in terms of the flow rate for a given rotational speed and pressure load. The optimal height of the channel becomes small as the rotational speed decreases or the pressure load increases. The flow rate of the pump is found to be in proportion to the width of channel.