• Composites Research
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• 제12권1호
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• pp.37-46
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• 1999

본 연구에서는 직접 설계 제작된 금형을 사용하여 임의의 적층각을 갖는 복합재 원통셸을 제작하였으며, 양단자유와 양단고정 경계조건에 대한 진동해석 및 모드시험을 수행하였다. 실험으로부터 구해진 고유진동수와 모드형상결과를 이론 및 유한요소해석 결과와 비교하였고 서로 잘 일치함을 확인하였다. 따라서 이러한 결과로부터 본 연구의 복합재 원통셸을 제작방법이 실험실 수준에서 손쉽게 고품질의 복합재 원통셸을 제작하는 성형법 연구에 기여할 수 있음을 알 수 있었다.

• 한국항공우주학회지
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• 제34권6호
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• pp.1-9
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• 2006

본 연구의 목적은 여러 가지 비행 모드 상의 로터 성능을 효율적으로 예측하는 것이다. 헬리콥터의 공력 특성을 예측하기 위한 비정상 source-doublet 패널 기법 기반의 수치 기법을 개발하였다. 후류의 형상 예측에는 시간 전진 자유후류모델이 사용되었다. 점성에 의한 확산을 고려한 후류의 roll-up 모사를 위하여 후류의 doublet 패널은 같은 강도의 와류고리로 대체하여 계산하였다. 후류와 양력면의 충돌 문제는 표면격자 내부에 들어간 와류고리의 포텐셜값을 제거하여 해결하였다. 제자리비행의 해석 시에 나타나는 와류 불안정성의 해결에는 slow starting과 vortex core growth 모델을 사용하였다. 로터 공력 해석 프로그램은 제자리비행과 전진비행에 대한 실험 결과와 비교하여 검증하였으며, 실험치와 일치하는 결과를 얻을 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.71-79
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• 2002

The characteristics of the catalytically supported combustion with Pd and Pd/Pt based catalyst using the bench-scaled high pressure combustor have been investigated up to 5atm. This study aimed to investigate combustion characteristics of the stable flame attached to the exit of catalyst bed and NOx emissions with respect to the position of axial and radial direction in the combustor. NOx emissions were increased along the axial distance after the catalyst bed exit and radially decreased from the center to the wall of the combustor. At the higher pressure, the NOx emission decreased slightly due to the lower flame temperature in the combustor at the high pressure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.413-418
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• 1996

Alternate pirn winding is more difficult to control than others because starting points of its traverse strokes are changed alternately through the winding operations. However, the alternate pirn winding is ye useful method because the yarn can be hardly broken when it is unwinded from full packaged bobbin. This paper presents kinematic control algorithm for the alternate pirn. The proposed algorithm can decide the values of control variables such as bobbin speed and traverse speed from the given input parameters and constraints by using the kinematic relations of the winding mechanism. The compute simulations and experimental verifications of the developed winding control algorithm are carried out It is concluded that the proposed algorithm is an efficient and reliable alternative to traditional trial and error control methods.

• 한국정밀공학회지
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• 제32권2호
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• pp.173-178
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• 2015

Laser-assisted machining (LAM) is an effective machining method for processing difficult-to-cut materials. Prediction and estimation of preheating effect of the LAM is difficult because of moving heat source. So it is necessary to study the preheating effect of the laser heat source irradiated on the curved surfaces of workpieces of various shape. In this paper, thermal analysis of the LAM for 3-dimentional workpiece with cylindrical shape was performed. The results of this analysis can be applied to obtain the optimal preheating method and path for LAM of 3-dimensional workpiece.

• 한국통신학회논문지
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• 제31권4C호
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• pp.400-406
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• 2006

3차원 정보 복원이나 형상 복원, 가상 물체 삽입 등의 과정을 수행하기 위해서는 영상 촬영에 사용된 카메라의 위치와 방향, 그리고 초점 거리 등의 변수가 필요하다. 본 논문에서는 이차원 영상간의 대응관계를 이용하여 카메라 내부 변수인 초점 거리를 추정하는 셀프 캘리브레이션(self-calibration) 과정에서 특징점의 위치가 초점 거리 추정에 미치는 영향을 분석하였다. 캘리브레이션에 사용하는 특징점과 주점과의 거리에 따라 초점 거리 추정 결과에 미치는 영향을 시뮬레이션을 통하여 검증하고, 이를 바탕으로 오차 민감도를 줄일 수 있는 특징점 선택 방법을 제안한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.404-409
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• 2000

The determination of surface morphology is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe morphology of various rubbed surface, the wear test was carried out under different experimental conditions in lubricating wear. And fractal descriptors was applied to rubbed surface of hydraulic driving material with image processing system. These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Morphology of rubbed surface can be effectively obtained by fractal dimensions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.950-953
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• 2002

Trepan prevents wear of an inside part of a bearing when the initial shaft rotates. It continuously contacts with the eccentric part of the shaft in rotation and is loaded repeatedly. Therefore, even if an early crack of a trepan part is small, a crack progresses by a repeated load. If a crack progresses, very small chips come out. This is pill in the rotor and prevents rotation of the compressor. There can be leaks in a microgroove and extreme wear can occur due to lack of oil on the surface contact pan. Therefore, this study was carried out to compare and investigate trepan strength and deflection characteristics between trepan locations and dimension changes using a finite element method and search a motor bearing for a model with bigger stiffness of a trepan part and the same deflection. And then. five different types of the oil groove model were chosen to prevent small crack and considered also machining ability and the analysis was carried out on oil feeding flow.

• 한국정밀공학회지
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• 제28권5호
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• pp.578-584
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• 2011

In mechanical cutting process, burr was generated at workpiece by cutting tool generally. It is working disturbance during manufacturing process. Besides burr was taken shape relatively large size more micro scale machining than macro scale machining. Many researches have been studied to remove micro burr(de-burring), because it was negative effect for accuracy of machining shape. However, micro de-burring was constrained by burr height, micro feature and so on. In this paper, experimental research was carried out to compare de-burring characteristics of $Al_2O_3$ abrasive and polymer.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.53-58
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• 2001

Fractal dimension is the method to measure the roughness and the irregularity of something that cannot be defined obviously by Euclidean dimension. And the analysis method of this dimension don't need perfect, accurate boundary and color like analysis lot diameter, perimeter, aspect or reflectivity of wear particles or surface. If we arranged the morphological characteristic of various wear particle by using the characteristic of fractal dimension, it might be very efficient to the diagnosis of driving condition. In order to describe morphology of various wear particle, the wear test was carried out under friction experimental conditions. And fractal descriptors was applied to boundary and surface of wear particle with image processing system. These descriptors to analyze shape and surface wear particle are boundary fractal dimension and surface fractal dimension.