• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.35-38
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• 2004

부틸알데히드로 오염된 대상 부지에 Biosparging 공법의 현장 적용을 위해 적정 공기 주입 압력 조건을 도출한 결과, 주 오염층인 자갈질 모래층에 공기주입 가능 파괴압력(Pe)는 약 300mmAq로 측정되었으며 4,500mmAq 압력 조건에서는 용존 산소농도의 영향 반경이 약 3 m로 나타났다. 위의 조건을 적용하여 약 150일간 운전한 결과, 영양물질을 투입하지 않은 초기 90일 동안 최고농도 대비 약 90%가 저감되었으며 그 이후에 영양물질을 투입하여 초기 최고 농도 대비 96%가 저감되어 복원목표치인 50ppm을 모든 지역에서 만족시켰다. 또한 생분해 반응속도가 k=0.03/day로 나타나 휘발성이 낮고 생분 해도가 뛰어난 부틸알데히드로 오염된 자갈질 모래층에 Biosparging공법이 성공적으로 적용된 사례이다.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.48-55
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• 2020

The use of temporary Gondola has been steadily increasing. The temporary Gondola is required to get a safety certification review during installation and to be inspected during use within every six months. Most of them, however, are dismantled before six months, and inappropriate activities are conducted frequently for shorter working hours and convenience of work. In this study, the characteristics of the temporary Gondola and the domestic accident cases that occurred over the past 10 years(2008-2017) are analyzed for the type of accident, the state of the accident by year, and the actions of the workers in the event of an accident. Also comprehensive accident reduction measures were proposed by identifying the fundamental causes of temporary Gondola accidents, problems of existing preventive measures, and system defects by utilizing Bow-Tie techniques.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.85-88
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• 2001

Since mountainous area has access restrictions for field work, assessors need to establish a conceptual model of the contamination prior to the field investigation. In this study we established a conceptual model of the contamination based on site inspection and geological survey, followed by the field investigation for the petroleum spill site. In the conceptual model, we estimated that tile contamination should have spread by groundwater and topographical characteristics within the top soil layer. The spread of contamination through rock was not considered in the conceptual model due to impermeable characteristics of metasyenite. The contaminated environmental media of the petroleum spill site include soil and groundwater. According to the analysis result of the contamination, the volume of contaminated soil is estimated approximately 4, 150 cubic meters (7, 055 ton) with most contaminants existing along the groundwater flow within top soil layer.

• The Mathematical Education
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• v.45 no.3 s.114
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• pp.367-373
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• 2006

This study suggests that it is necessary to prove that the values of three areas of a triangle, which are obtained by the multiplication of the respective base and its corresponding height, are the same. It also seeks to deeply understand the meaning of Area formula of triangles by exploring some questions raised in the analysis of the proof. Area formula of triangles expresses the invariance of congruence and additivity on one hand, and the uniqueness of parallel line, one of the characteristics of Euclidean geometry, on the other. This discussion can be applied to introducing and developing exploratory learning on area in that it revisits the ordinary thinking on area.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.93-101
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• 2002

The effect of nonlinear friction in the low velocity is dominant in precise controlled mechanisms and it is difficult to identify the friction effect. The friction model which Canudas suggested so called, LuGre model is well expressed the friction effect as Streibeck in the law velocity. But it\`s model parameters were estimated continuously in operation for precise control. This paper suggests the sliding mode controller and observer for compensating the friction effect. Experimental results for a ball-screw system show that the proposed method has a good performance especially in the low velocity.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.433-435
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• 2008

본 연구에서는 MR 유체를 특징으로 하는 대시포트형 마운트를 제안하고, 자극 형상의 변화가 MR유체 마운트의 감쇠력에 미치는 영향에 대하여 고찰하였다. 제안된 MR유체 마운트의 코어부에 발생하는 자기 특성에 대하여 살펴보기 위하여 자극(Magnetic pole)의 유효길이와 코어 중심부의 구조를 달리하여 대시포트를 제작하였다. 등가자기회로를 이용한 대략적인 계산방법에 의한 결과 자극의 유효길이가 증가할수록 자기저항은 감소하는 경향을 나타내지만, 그 밖의 설계인자들의 영향은 작게 나타났다. 상용해석프로그램을 이용하여 등가자기회로 결과와 비교를 하였으며, 대시포트 마운트를 제작하여 자극의 유효길이 변화에 대한 감쇠력의 변화를 실험적으로 비교하였다.

• Journal for History of Mathematics
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• v.30 no.5
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• pp.261-287
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• 2017

De Zolt's axiom which is a precise formulation of Euclid's Common Notion 5, "the whole is greater than the part", for the notion of 'content' holds in any Hilbert plane. In this article, we study the history of de Zolt's axiom which has its origin in Euclid's Common Notions, and introduce an example of a plane geometry in which de Zolt's axiom does not hold. We show that there is no area function in this geometry and every square is equidecomposable with a square which is properly contained in the first one. From this we also show that there are two equidecomposable rectangles which have the same base and do not have the same altitude, and there is a rectangle which is equicomplementable with an emptyset.

• Food Science and Preservation
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• v.2 no.1
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• pp.147-154
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• 1995

The influence of packaging methods(punched, vacuum, shrinked), mature stages(mature-green, completely ripe) and storage temperatures(5$^{\circ}C$, $25^{\circ}C$) on the shelf-life and quality were Investigated in tomatoes. Weight-loss was reduced by the treatment of polyethylene film packaging(vacuum>shrinked>punched) and the effect was more outstanding at 5$^{\circ}C$ than $25^{\circ}C$. The soluble solid content of completely ripe tomato was higher than mature green tomato, but acidity and firmness were lower. Soluble solid contents increased in the begining and decreased after that. Acidity and firmness de creased gradually during the storage. The decrease of acidity and firmness in mature-green tomato was lower than completely ripe one, at 5$^{\circ}C$ than $25^{\circ}C$ and shrinked packaging than non packaging. The shelf-life of mature-green tomato in shrinker packaging was longest, 17 days at $25^{\circ}C$ and 21 days at 5$^{\circ}C$.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.281-284
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• 2019

본 논문은 CNN (Convolution Neural Networks)의 첫 번째 컨볼루션층(convolution layer)을 RGB-csb(RGB channel separation block)로 대체하여 입력 영상의 RGB 값을 특징 맵에 적용시켜 정확성을 제고시킬 수 있는 선행연구 결과에 추가적으로, 훈련 및 시험 영상 수에 따른 분석을 통하여 정확도 향상방법을 제안한다. 제안한 방법은 영상의 개수가 작을수록 각 학습 간의 정확도 편차가 크게 나타나는 불안정성은 있지만 기존 CNN모델에 비하여 정확도 차이가 증가함을 알 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.27-29
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• 2022

최근 인공지능 애플리케이션이 많이 사용되고 이러한 애플리케이션에서 데이터 희소성이 높아지고 있어 이러한 희소 데이터를 효율적으로 처리하기 위한 하드웨어 구조들이 많이 소개되고 있다. 본 논문에서는 희소 데이터 처리 시 전력 소모량을 낮출 수 있는 새로운 하드웨어 구조를 제안한다. 일반적인 인공지능 하드웨어에서 많이 사용되는 시스톨릭 어레이 구조를 기반으로 하며, 제안된 저전력 PE 가 희소 데이터 처리시 희소하지 않은 데이터 처리 시보다 최대 2 배의 전력 소모량을 줄일 수 있는 것으로 나타났다.