• 대한전기학회논문지:시스템및제어부문D
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• 제53권7호
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• pp.501-508
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• 2004

In this paper, a coordinated scheduling algorithm is proposed to reduce end-to-end delay in distributed control of systems. For the algorithm, the analysis of practical end-to-end delay in the worst case is performed priory with considering implementation of the systems. The end-to-end delay is composed of the delay caused by multi-task scheduling of operating systems, the delay caused by network communications, and the delay caused by asynchronous timing between operating systems and network communications. Through some simulation tests based on CAN(Controller Area Network), the proposed worst case end-to-end delay analysis is validated. Through the simulation tests, it is also shown that a real-time distributed control system designed to existing worst case delay cannot guarantee end-to-end time constraints. With the analysis, a coordinated scheduling algorithm is proposed here. The coordinated scheduling algorithm is focused on the reduction of the delay caused by asynchronous timing between operating systems and network communications. Online deadline assignment strategy is proposed for the scheduling. The performance enhancement of the distributed control systems by the scheduling algorithm is shown through simulation tests.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.321-325
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• 2000

To obtain precise surface and high productivity, high speed end milling has been studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other researchers. Between simulated results and experiment results, good agreements were obtained.

• 대한기계학회논문집A
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• 제25권2호
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• pp.228-234
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• 2001

To obtain precise machined surface and high productivity in machining, high speed end milling has beed studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other investigators. Good agreements were obtained between simulated results and experimental results.

• Journal of Astronomy and Space Sciences
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• 제24권1호
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• pp.69-78
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• 2007

Earth-Sun-Heliosphere Interactions Experiments(EARTHSHINE) 미션의 주 탑재체인 Albedo Monitor and Radiometer(Amon-Ra) 광학계는 최초로 제1 라그랑제 지점(Lagrange point 1) 주위의 혜일로(Halo) 궤도에 위치하여 태양 복사 활동 및 지구 반사율 변화를 1% 정확도 이내로 측정함으로서 현존하는 지구 반사율 추이의 모순을 해결할 수 있는 과학적 측정 자료를 제시하는데 그 목적을 가지고 있다. 이에 이미 개발된 광학 성능 검증용 Amon-Ra 광학계의 가시광채널 시험 모델 및 광선 추적 기법을 이용한 통합적 광선 추적 end-to-end 과학 임무 성능 평가 수치 모사 기법을 확립하였으며, 개발된 기법을 이용하여 실제 제작된 Amon-Ra 광학계를 제1라그랑제 지점에 위치시키고 태양과 지구 밝기를 다양하게 변화시킨 후 광학계에 입사되는 에너지 복사량을 수치 모사로 측정하였다. 관측된 지구 및 태양 밝기로부터 지구 반사율 변환을 위하여 각 분포 모델(GLobal Angular Distribution Model, ADM)을 이용하였으며 수치 모사에 의한 지구 반사율 측정 결과를 Amon-Ra 광학계의 측정 오차 범위인 ${\pm}0.28%$와 비교함으로서 개발된 end-to-end 성능 검증 기법의 계산 정밀도를 확인하였다. 이는 기존의 광학계 성능 검증법의 한계를 뛰어넘어 광학계 성능 평가를 실시간으로 검증할 수 있다는 점에서 큰 의의를 지닌다.

• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.369-374
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• 2011

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

• 한국정밀공학회지
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• 제23권6호
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• pp.151-159
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• 2006

This paper describes a design process of end-milling cutters: solid model of the designed cutter is constructed along with computation of cutter geometry, and the wheel geometry as well as wheel positioning data f3r fabricating end-mills with required cutter geometry is calculated. In the process, the main idea is to use the cutting simulation method by which the machined shape of an end-milling cutter is obtained via Boolean operation between a given grinding wheel and a cylindrical workpiece (raw stock). Major design parameters of a cutter such as rake angle, inner radius can be verified by interrogating the section profile of its solid model. We studied relations between various dimensional parameters and proposed an iterative approach to obtain the required geometry of a grinding wheel and the CL data for machining an end-milling cutter satisfying the design parameters. This research has been implemented on a commercial CAD system by use of the API function programming, and is currently used by a tool maker in Korea. It can eliminate producing a physical prototype during the design stage, and it can be used for virtual cutting test and analysis as well.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.850-853
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• 2004

The development of 3D CAM system for the manufacturing of end mills becomes a key approach to save the time and reduce cost for end mills manufacturing. This paper presents the calculation and simulation of end mill tools CNC machining bases on 5-axes CNC grinding machine tool. In this study describes the process of generation and simulation of grinding point data between the tool and the grinding wheels through the machined time. Depend on input data of end mill geometry, wheels geometry, wheel setting, machine setting the end mill configuration and NC code for machining will be generated and visualized in 3 dimension before machining. The 3D visualizations of end mill manufacturing was generated by using OpenGL in C++. The development software was designed by using Microsoft Visual C++, which has many advantages for users, saving time and reducing manufacturing cost.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.928-933
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• 2004

A new approach for modelling and simulation of the cutting forces in end milling processes is presented. In this approach, the cutting forces in end milling are modelled based on a predictive machining theory, in which the machining characteristic factors are predicted from input data of fundamental workpiece material properties, tool geometry and cutting conditions. In the model, each tooth of a end milling cutter is divided into a number of slices along the cutter axis. The cutting action of each of the slices is modelled as an oblique cutting process. For the first slice of each tooth, it is modelled as oblique cutting with end cutting edge effect, whereas the cutting actions of other slices are modelled as oblique cutting without end cutting edge effect. The cutting forces in the oblique cutting processes are predicted using a predictive machining theory. The total cutting forces acting on the cutter is obtained as the sum of the forces at all the cutting slices of all the teeth. A Windows-based simulation system for the cutting forces in end milling is developed using the model. Experimental milling tests have been conducted to verify the simulation system.

• 정보처리학회논문지C
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• 제18C권1호
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• pp.31-44
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• 2011

네트워크 기반의 적절한 컴퓨팅은 네트워크 대역폭의 가용성에 의존한다. 백본 네트워크 용량과 액세스 네트워크 상에 심각한 버틀넥이 발생하여 ISP 사업자와 고객 간의 갭이 발생된다면 그만큼 ISP 사업자는 사업에 불이익을 초래할 수 있다. 이러한 상황이 발생되기 이전 ISP 사업자가 트래픽량 예측과 종단간 오버로드가 높은 링크 구간을 감지할 수 있다면 ISP 사업자와 고객 간의 갭은 그만큼 줄어 들 수 있을 것으로 판단된다. 따라서 본 논문은 트래픽량 예측과 종단간 오버로드가 높은 링크 구간을 감지 가능한 소프트웨어로 ACE, ADM, Flow Analysis를 소개한다. 이들 툴을 이용하여 전자상거래의 연속적인 트랜잭션을 실망에서 측정한 후 측정된 네트워크 데이터를 가상 망 환경에 임포트하고 백그라운드 트래픽을 생성한다. 이와 같은 가상 망 환경을 토대로 점차적인 사용자 수 증가에 따른 트래픽량 예측과 링크 로드가 높은 구간을 시뮬레이션 결과로 알 수 있었다.

• 한국공작기계학회논문집
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• 제17권1호
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• pp.113-119
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• 2008

The purpose of the present paper is to investigate the optimal shape of the brake tube-end and flare nut for automobiles using the $DEFORM^{TM}-3D$, finite element code. A flare nut is a small and important part used to join a brake tube-end in automobiles. In this instance, we studied the optimal forging processes for the tube-end and flare nut. Finite element analysis has been carried out to predict an optimal shape of the tube-end and flare nut. Also the simulation results were reflected to the forging processes design for the tube-end and flare nut. The shape of the tube-end and flare nut is in agreement with the finite element simulation and the test results.