• Journal of the Korean Society of Radiology
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• v.85 no.3
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• pp.607-617
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• 2024

Purpose Recent studies have demonstrated the usefulness of diffusion-weighted MR neurography (DW MRN) for assessing nerve roots. This study aimed to evaluate the utility of DW MRN with a unidirectional motion-probing gradient (MPG) for the lumbar nerve roots at 1.5T MR. Materials and Methods Sixty-four lumbar spine MRI scans with DW MRN using anteroposterior unidirectional MPG were retrospectively analyzed. Any changes in the 512 lumbar spinal nerve roots from L3 to S1 were evaluated using T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE T1WI), and DW MRN, with agreement and correlation analysis. Results T2WI revealed compression of 78 nerve roots, and CE T1WI revealed 52 instances of nerve root enhancement. Sixty-seven nerve roots showed swelling and hyperintensity on DW MRN. A total of 42 nerve roots showed changes in the CE T1WI and DW MRN sequences. Moderate to substantial agreement and moderate positive correlation were observed between DW MRN and CE T1WI, as well as DW MRN and T2WI (κ = 0.59-0.65, ρ = 0.600-0.653). Conclusion DW MRN with unidirectional anteroposterior MPG can help evaluate neuritisrelated changes in spinal nerve roots and could serve as a sequence capable of complementing or substituting gadolinium CE imaging.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.361-363
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• 2013

비파괴 검사란 재료나 제품을 원형과 기능에 변화를 주지 않고 실시하여 원하는 정보를 획득할 수 있는 검사를 의미한다. 비파괴검사는 점검자의 육안 조사를 통한 수작업으로 이루어지고 있기 때문에 점검자의 주관이 개입되며, 점검자에 따라 검사 결과의 차이가 있을 수 있으므로 신뢰도의 차이가 발생하게 된다. 그러므로 본 논문에서는 비파괴 검사를 이용하여 획득한 세라믹 소재 영상에서 효율적으로 결함을 검출하는 방법을 제안한다. 제안된 방법은 세라믹 소재 영상에 가우시안 필터링 기법을 적용하여 잡음을 제거하고, Ends-in Search Stretching 기법을 적용하여 명암 대비를 강조한다. 명암 대비가 강조된 영상에 샤프닝 기법을 적용하여 윤곽선을 강조한다. 윤곽선이 강조된 영상에 $3{\times}3 $ Roberts 마스크를 적용하여 강조된 윤곽선을 추출하고, Glassfire 기법을 적용하여 라벨링한 후, 시그마 퍼지 이진화 기법과 형태학적 정보를 이용하여 잡음을 제거하고 결함 영역을 검출한다. 제안된 방법을 세라믹 소재 영상을 대상으로 실험한 결과, 효율적으로 결함을 검출하는 것을 확인할 수 있었다.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.149-154
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• 2011

The purpose of this study was to examine the usefulness of diffusion weighted images in breast MRI by performing a quantitative comparative analysis in patients diagnosed with DCIS. On a 3.0T MR scanner, diffusion weighted images and ADC map images were obtained from 20 patients histologically diagnosed with ductal carcinoma in situ (DCIS). The findings from the quantitative image analysis are the following: The diffusion weighted images showed higher SNR and CNR at the lesion area. In addition, the ADC values were lower at the lesion area.

• The Korean Journal of Archival Studies
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• no.50
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• pp.5-60
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• 2016

This paper considers the relationship between ethics and archives by asking the question "who is the archivist?". Aside from this, the researcher also emphasized the following theses. First, archival science should search for ethics as a discourse and not just the Code of Ethics. Second, an archivist should state his/her view in their archives field. Third, archival science should search for both personal and practical knowledge. Aside from these, this article argues also that an epistemological approach is necessary for ethics.

• Education of Primary School Mathematics
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• v.26 no.4
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• pp.257-275
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• 2023

In this study, we designed and implemented a instruction emphasizing mathematical argument for fifth-grade students and analyzed the teaching practices. Through a literature review related to instruction emphasizing mathematical argument, we organized a teaching model of five phases that explain why the general claim that the sum of consecutive odd numbers equals a square number is true: 1) noticing patterns, 2) articulating conjectures, 3) representing through visual model, 4) arguing based on representation, 5) comparing and contrasting. Then, we analyzed the argumentation stream by phases to observe how the instruction emphasizing mathematical argument is implemented in the elementary classroom. Based on the results of this study, we discuss the implications of teaching a mathematical argument in elementary school.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.135-141
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• 1997

Purpose: To assess the usefulness of breath-hold fast MR imaging of liver with fat suppression (FS) by application of chemical saturation technique in the diagnosis of regional fatty changes suspected in sonography. Materials and Methods: Thirteen patients who had focal lesions with diffuse, homogeneous signal changes after FS through chemical saturation technique without additional changes of imaging parameter during MR imaging of liver were selected. T1-weighted fast low-angle shot and T2-weighted turbo spin-echo sequences were obtained with or without FS during each single breath-holding session. Subjective changes of signal intensity between the pre-FS and the FS images were compared with the sonographic findings in each lesion. Results: Seven lesions of decreased signal intensity after FS on T1 or T2-weighted images, including three lesions only at FS T1 images, were regarded as focal fat infiltration. All seven lesions had compatible sonographic findings as homogenously echogenic areas. Another six lesions of subjectively increased signal intensity including two lesions only at FS T2 images were regarded as focal fat sparing. All six lesions had sonographic findings as homogenous echo poor areas suggesting focal fat sparing. In cases regarded as fat infiltration, score changes were more prominent at FS T1 images than FS T2 images(p=0.0002). In cases regarded as fat sparing, score changes were more prominent at FS T2 images than FS T1 images(p=0.042). Conclusion: Breath-hold fast T1 and T2-weighted MR imaging with and without chemical saturation pre-pulse may be sufficient for characterization of regional fatty changes in the differential diagnosis of focal hepatic lesion found at sonography.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.116-123
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• 2003

Purpose : The present study was undertaken to evaluate the usefulness of cerebral diffusion (DWI) and perfusion MR imaging (PWI) in rabbit models with hyperacute cerebral ischemic infarction. Materials and Methods : Experimental cerebral infarction were induced by direct injection of mixture of Histoacryl glue, lipiodol, and tungsten powder into the internal cerebral artery of 6 New-Zealand white rabbits, and they underwent conventional T1 and T2 weighted MR imaging, DWI, and PWI within 1 hour after the occlusion of internal cerebral artery. The PWI scan for each rabbit was obtained at the level of lateral ventricle and 1cm cranial to the basal ganglia. By postprocessing using special imaging software, perfusion images including cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) maps were obtained. The detection of infarcted lesion were evaluated on both perfusion maps and DWI. MTT difference time were measured in the perfusion defect lesion and symmetric contralateral normal cerebral hemisphere. Results : In all rabbits, there was no abnormal signal intensity on T2WI. But on DWI, abnormal high signal intensity, suggesting cerebral infarction, were detected in all rabbits. PWI (rCBV, CBF and MTT map) also showed perfusion defect in all rabbits. In four rabbits, the calculated square of perfusion defect in MTT map is larger than that of CBF map and in two rabbits, the calculated size of perfusion defect in MTT map and CBF map is same. Any rabbits do not show larger perfusion defect on CBF map than MTT map. In comparison between CBF map and DWI, 3 rabbits show larger square of lesion on CBF map than on DWI. The others shows same square of lesion on both technique. The size of lesion shown in 6 MTT map were larger than DWI. In three cases, the size of lesion shown in CBF map is equal to DWI. But these were smaller than MTT map. The calculated square of lesion in CBF map, equal to that of DWI and smaller than MTT map was three. And in one case, the calculated square of perfusion defect in MTT map was largest, and that of DWI was smallest. Conclusion : DWI and PWI may be useful in diagnosing hyperacute cerebral ischemic infarction and in e-valuating the cerebral hemodynamics in the rabbits.

• Proceedings of the KGS Conference
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• 2002.11a
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• pp.123-126
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• 2002

교수-학습 방법 발전이 필요하다는 논리와 관련해서 선진국들의 교육 추세를 눈여겨볼 필요가 있다. 첫째, 교육이라는 행위가 교사가 주도하는 교수(teaching, instruction)로부터 학생이 주도하는 학습 (learning)으로 바뀌어 가는 추세이고, 둘째, 학습에 있어서 자극-반응 모델에 기초한 반응에는 강조를 두지 않고 인지(cognition), 즉 지각과 사고를 강조하고 있는 추세이며, 셋째, 따라서 학생이 학습을 제대로 해 가는 데 필요한 여러 가지 방략(strategy), 가령 구성적 방략이나, 비고츠키 모델 등이 개발되거나 원용되고 때로는 기존 방략들(탐구적 방법, 문제해결 방법 등)이 재 강조되면서, 그 방략들이 학생들에게 유효하도록 가르쳐 지고 있는 실정이다.(중략)

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.1006-1008
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• 2011

화장품 시장은 유통에 따라서 가격, 디자인, 제품 등의 요소가 결정되는 특수한 성격이 강하다. 본 연구에서는 화장품 특판 시장에서 나타나는 디자인적 차별성을 살펴 보고 향후 발전 방안을 모색해보고자 하는데 있다. 연구결과, 바디케어 특판 화장품의 경우 차별화를 강조한 형태, 함량을 강조한 형태, 사용자의 사용성을 강조한 형태등이 가장 큰 고려 대상이었다. 그리고 특판 시장의 경우에는 가격 경쟁력 문제를 디자인으로 보완할 수 있는 부분이 있다는 것을 알 수 있었다.

• Communications of Mathematical Education
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• v.10
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• pp.221-236
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• 2000

오늘날 우리의 교육은 교육과정에 나와 있는 내용의 구성에 대해서는 어떤 부분을 강조해야 하는가? 그리고 왜 강조해야 하는가?에 대해서 학생들에게 잘 전달하지 않은 채, 어려운 공식 ${\cdot}$ 원리 ${\cdot}$ 법칙 등의 유도와 문제풀이 등으로 인해 학생들은 점점 수학에 대해 흥미를 잃고 있다. 본 연구에서는 현행 고등학교 수학에서의 미분과 적분 단원의 내용 구성에 있어서 문제점을 살펴보고, 수학 학습이 학습자에게 좀더 의미 있는 활동이 되도록 미분과 적분 단원의 내용에 대한 바람직한 지도계열에 대해서 살펴보고, 지도시 특히 강조해야 할 점들을 대학수학에서의 이론적 배경을 토대로 살펴본다.