• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.336-339
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• 2001

In this study an experimental investigation was conducted to find the grinding characteristics of ceramics, as compared to STDll and SUS304 materials. The grinding force and the microscopic observation of the workpieces were obtained in surface grinding. It has been found that the grinding force of ceramics is relatively low as compared to that of steels and that CBN wheel has an excellent performance.

• 국토계획
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• 제54권2호
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• pp.5-16
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• 2019

The purpose of this study is to analyze the spatial characteristics of business-type-changed parcel in the Hongik-University commercial area, from the view point of commercial gentrification. A commercial gentrification occurs through a business-type-change in a spatial basic unit (microscopic spatial unit such as parcel) of an area which has not been considered in relavent policies and research. So, this study analyzed the spatial characteristics of business-type-changed parcels using the Cox's proportional hazard regression model. The main results of this study are as follows. First, as new developments in the adjacent area occur, the business-type-change probability increases. Second, by the commercial area division, the business-type-change probability is different. Finally, the accessibility is better, the probability is higher. These results could suggest that a consideration of the spatial characteristics form microscopic viewpoint is necessary to understand the commercial gentrification. And these could be used as basic data for a gentrification diagnostic and management system, which can predict gentrification from the view point of business-type-change on the basis of a parcel.

• Tribology and Lubricants
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• 제27권3호
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• pp.147-155
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• 2011

The ceramic coatings are excellent materials of cutting tools and sliding parts. To evaluate the wear characteristics of very thin ceramic coated layer, it is very important to investigate its wear process microscopically. An effective method for investigating the wear of a thin layer is the observation of wear process in microscopic detail using in-situ system. In this study, using the SEM Tribosystem as in-situ system, the microscopic wear mode of TiN coatings was investigated in repeated sliding. As results, four modes were observed for TiN coatings: Ploughing, powder formation, flake formation and coating delimitation. The observation of the microscopic wear by in-situ system can clarify the allowable stress of TiN coating.

• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1177-1186
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• 2004

In this paper, the spray atomization characteristics of a gasoline direct-injection injector were investigated experimentally and numerically. To visualize the developing spray process, a laser sheet method with a Nd :YAG laser was utilized. The microscopic atomization characteristics such as the droplet size and velocity distribution were also obtained by using a phase Doppler particle analyzer system at the 5 ㎫ of injection pressure. With the experiments, the calculations of spray atomization were conducted by using the KIVA code with the LISA-DDB breakup model. Based on the agreement with the experimental results, the prediction accuracy of LISA-DDB breakup model was investigated in terms of the spray shapes, spray tip penetration, SMD distribution, and axial mean velocity. The results of this study provides the macroscopic and microscopic characteristics of the spray atomization, and prediction accuracy of the LISA-DDB model.

• 정보통신설비학회논문지
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• 제8권4호
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• pp.170-181
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• 2009

When a slow-moving vehicle occupies one of the lanes of a multi-lane highway, it often causes queuing behind, unlike one is caused by an actual stoppage on that lane. This happens when the traffic flow rate upstream from the slow vehicle exceeds a certain critical value. This phenomena is called as the Moving Bottleneck, defined by Gazis and Herman (1992), Newell (1998) [3], and Munoz and Daganzo (2002), who conducted the flow estimates of upstream and downstream and considered slow-moving vehicle speed and the flow ratio exceeding slow vehicle and the microscopic traffic flow characteristics of moving bottleneck. But, a study of delay on moving bottleneck was not conducted until now. So this study provides a average delay time model related to upstream flow and the speed of slow vehicle. We have chosen the two-lane highway and homogeneous traffic flow. A slow-moving vehicle occupies one of the two lanes. Average delay time value is a result of AIMSUN[9], the microscopic traffic flow simulator. We developed a multiple regression model based on that value. Average delay time has a high value when the speed of slow vehicle is decreased and traffic flow is increased. Conclusively, the model is formulated by the negative exponential function.

• 비파괴검사학회지
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• 제19권1호
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• pp.25-33
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• 1999

콘크리트는 다상(multi-phase)의 재료로서 구성되어지는 복합재료의 일종으로써 준취성(quasi-brittle)적인 재료적 특성을 가지고 있기 때문에 실제 복잡한 미시적 파괴특성을 나타낸다. 따라서 콘크리트 구조물의 안전성 확보를 위해서는 먼저 하중의 증가에 따른 콘크리트 내부의 변형특성 및 미시적 파손기구를 파악하여야 하며, 특히 실제 구조물에 있어서는 이들 특성들을 비파괴적으로 상시 (on-line) 모니터링 하여야 할 필요가 있다. 따라서 본 연구에서는 3점 굽힘 하중을 받는 콘크리트 부재의 미시적 파손기구 및 각 파손기구에 대한 AE 특성을 명확히 함으로써 콘크리트 부재의 미시적 손상 및 파괴 특성을 비파괴적으로 평가하고 AE 발생원 위치 추정 기법을 이용하여 균열 발생 및 진전거동을 평가하였다.

• 한국공작기계학회논문집
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• 제11권1호
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• pp.26-31
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• 2002

In this study an experimental investigation was conducted to find the grinding characteristics of ceramics, STD11 and STS304 materials. The grinding force and the microscopic observation of the workpieces were obtained in surface grinding. Grinding characteristics of ceramics were inspected through the microscopic examination the cutting force, and the surface roughness. It has been found that the finding force of ceramics is relatively low as compared to that of steels and that CBN wheel has an excellent performance. The surface roughness was measured according to the feedrate and the depth of out.

• 한국농공학회논문집
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• 제52권4호
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• pp.93-101
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• 2010

The purpose of this study is to provide basic data for utilization in environment-friendly and economically outstanding CSG construction method by physical and mechanical properties of CSG materials including characteristics of uniaxial compressive strength, microscopic structure and freezing and thawing resistance in accordance with the cement content and curing time of the cement, and size of specimen. In this study, specimens with cement content of 4, 6, 8 and 10% of the total weight were, and, in order to examine the characteristics of the sizes of specimen, specimens with ${\Phi}50{\times}100mm$, ${\Phi}100{\times}200mm$ and ${\Phi}150{\times}300mm$ were manufactured to assess the features including compressive strength, microscopic structure, freezing and thawing, and degree of wet-dry. As results, it was found that with greater size specimen or contents of cement in the specimen, compressive strength, freezing and thawing resistance, and wet-dry resistance increase. Moreover, reactive products for each size of specimen were examined and it was possible to verify that some typical needle structured ettringite was generated due to blending of cement through microscopic structure analysis such as SEM and EDS analysis.

• Tuberculosis and Respiratory Diseases
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• 제72권2호
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• pp.197-202
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• 2012

Microscopic polyangiitis is a necrotizing vasculitis, characterized by inflammation of small vessels (capillaries, venules, and arterioles) with few or no immune deposits. The kidneys are the most commonly affected organs and are involved in 90% of patients, whereas pulmonary involvement occurs in a minority of cases (10% to 30%). In cases of lung disease, diffuse alveolar hemorrhage with pulmonary capillaritis is the most common manifestation. Microscopic polyangiitis is strongly associated with antineutrophil cytoplasmic autoantibody, which is a useful diagnostic serological marker. We report a case of microscopic polyangiitis presented as pleural effusion in a 67-year-old female. Pleural effusions have been reported in some cases previously, but the number of cases were small and their characteristics have not been well described. This report describes characteristic findings of pleural fluid and its histological features in a case of microscopic polyangiitis.

• 대한화학회지
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• 제67권4호
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• pp.241-252
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• 2023

이 연구는 학생들이 어려워하는 화학의 여러 개념 중 하나인 동적 평형에 대한 학생의 이해를 높이는 것을 목적으로 한다. 동적 평형은 입자들의 끊임없는 움직임과 상호 작용을 미시적으로 이해하고, 이를 통해 발현되는 거시적인 특성을 이해할 수 있도록 실제와 표상이 겹친 준미시적 수준으로 다루어야 한다. 하지만 9종의 화학 I 교과서를 분석한 결과 평형에 대한 표현 방식은 다소 한계가 있었다. 준미시적 표상 접근을 통해 평형을 이해할 수 있는 전략으로 스크래치를 활용한 수업을 4차시로 구안 하였고, 56명 학생을 대상으로 실행하였다. 4차시 수업은 6단계로 구성이 되며, 단계적으로 평형을 이해하도록 설계하였다. 사전 검사와 사후 검사를 비교한 결과, 학생들이 화학 평형에 대해 미시적 설명과 거시적 설명을 모두 옳게 하는 학생이 크게 증가하였다. 이를 통해 준미시적 표상의 접근 방식으로 스크래치를 활용한 수업의 적용 가능성을 엿볼 수 있었다.