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권은성(Eunsung Kwon),박기환(Kyihwan Park) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Non-ferrous metals cannot be magnetically sorted so they use color sorting or hand sorting. Therefore the sorting performance and recycling rate is low. To improve this, researches are being conducted to develop a device for automatic metal sorting system based on the laser induction technology, which is a chemical analysis method. For laser irradiation, the position of the metal on the conveyor must be known. For this task, we use triangulation method using line beam laser and camera. 3D shape can be obtained by triangulation method. In this shape measurement process, when the surface of the metal is highly curved, one metal can be recognized as two. Also, since the process of calculating the shape of actual metal goes frame-by-frame, an object may be divided into two frames therefore two positions can be calculated. For laser irradiation, only one position in one metal should be calculated. Therefore, in this study, we try to determine whether two or more positions are generated from one metal by calculating the distance between the positions of the calculated metal in each frame.
모바일 로봇 네비게이션을 위한 Lock-in Amplifier 방식의 레이저 거리 측정기
윤희선(Heesun Yoon),박기환(Kyihwan Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Map building is the most important thing for the mobile robots navigation. It requires specific vision system such as CCD camera, range finding system, and many other things. Laser range finder has highly collimated beams can be obtained easily, thus achieving lateral resolution, and short wavelengths involved cause the light to be backscattered, rather than reflected by the target. For the signal processing, the Lock-in amplifier system is addressed in this paper. We used a diffused reflected beam to detect phase shift in this system. But this beam is minuteness signal so it can be easily buried in nose. Lock-in amplifier is used to measure the amplitude and phase of signals which are buried in noise.
3 차원 형상 측정을 위한 Z 축 자동 간격 유지 제어 방식의 CCD 레이저 변위 센서 시스템
최교순(Gyosoon Choi),박기환(Kyihwan Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
There are two types for 3-D shape measurement, contact and non-contact types to measure shape data of a model and to know the accuracy of the model. However, the non-contact optical type is superior to the contact type for the convenience and accuracy. Among various non-contact optical types, a type of CCD laser displacement sensor system has the disadvantages of the structure of complicated signal processing and a large amount of data. However, the CCD sensor system is able to acquire each pixel data; therefore, it is easy to process data for user's purpose. In this paper, the CCD laser displacement sensor system of Z-axis constant range control method shows better advantages of linearity and accuracy than the system not using the above constant range control method.
자속 감소를 고려한 와전류식 제동보조장치의 제동력 유한요소해석
박선균(Seon-gyun Bak),박기환(Kyihwan Park),유창희(Chang-hee Yoo) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
와전류 제동장치의 제동 토크는 전자석에 의한 자기장과 회전자의 내측 표면에 생성되는 와전류의 상호 작용에 의해 발생된다. 그러나 와전류에 의해 발생하는 반대 방향의 자속으로 인한 총자속 감소에 의해 특정 속도를 기점으로 토크가 감소하기 시작하여 고속 영역에서 제동 효과가 저하된다. 따라서 와전류로 인한 자속 감소 효과를 고려하는 것이 제동장치의 성능 파악에 필수적이다. 본 연구에서는 유한요소법을 이용하여 회전자의 내부에서 발생하는 와전류와 총자속을 수치적으로 구하였다. 로터와 자극을 구성하는 재질의 투자율의 비선형성도 고려하였다. 해석 결과 제동 토크는 회전 속도가 증가함에 따라 최대점을 지나 감소함을 확인하였다. 해석을 통한 제동 토크와 실험으로 구한 값은 유사한 속도 영역에서 최대치를 보였다. The braking torque for eddy current retarders is the result of interaction of the magnetic flux and eddy currents on the rotor. Meanwhile, the secondary magnetic fluxes induced by eddy currents decrease the net fluxes, resulting in the reduction of braking torques. To calculate the braking torques and estimate the operating speed range accurately, the secondary magnetic effect due to eddy currents is a crucial factor. By using finite element methods, the eddy currents and net magnetic flux on the inner side of the rotor were calculated numerically. The nonlinearity of material permeability of the rotor and the poles was considered. Braking torques with respect to the rotor rpm were diminished after the maximum value. The numerical solution was in fair agreement with the experimental results.