• 전자공학회논문지 IE
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• v.43 no.4
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• pp.28-36
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• 2006

In this paper, an algorithm to classify the 4 motions of arm and a control system to position control the prosthesis are studied. To classify the 4 motions, we use flex sensors which is electrical resistance type sensor that can measure warp of muscle. The flex sensors are attached to the biceps brchii muscle and coracobrachialis muscle and the sensor signals are passed the sensing system. 4 motion of the forearm - flexion and extension, the pronation and supination are classified from this. Also position of forearm is measured from the classified signals. Finally, A two D.O.F prosthesis arm with RC servo-motor is designed to verify the validity of the algorithm. At this time, fuzzy controller is used to reduce the position error by rotary inertia and noise. From the experiment, the position error had occurred within about 5 degree.

• 기계와재료
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• v.23 no.3
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• pp.96-113
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• 2011

녹색기술 및 친환경 공정의 필요성이 급증함에 따라 재료이용률 향상을 지향하는 차세대 압출공정의 대두가 필요하게 됨에 따라 유압 CNC(Servo) 제어를 이용한 가변단면 압출기술을 개발하게 되었다. 이러한 가변단면 압출(Varied section extrusion, VSE)기술은 공정 중에 압출구를 빠져 나가는 소재의 단면 형상을 변화시켜 재료이용률을 향상을 도모하였으며, 후가공 공정의 생략도 가능하여 국내 압출업체의 생산원가 절감 및 글로벌 기술경쟁력 확보에 큰 도움을 줄 수 있을 것이다. 아직은 소수의 선진국에서 시도한바 있으나 양산품 적용에는 생산원가 및 생산속도, 상품성 등에 문제가 있어 자동차 부품 적용에 한계를 보이고 있는 기술이다. 따라서 본 연구팀이 가변단면 압출용 금형을 포함한 최적의 압출공정 및 양산성 문제의 해결점을 거의 확보하고 있는 단계로 세계를 선도하는 리딩기술(Leading technology)을 보유하게 됨으로써 국가의 기술경쟁력 향상에 중요한 역할을 수행할 수 있을 것이다. 본 연구의 내용을 요약하여 정리해 보면 첫째로는 CNC 제어 가변단면 압출공정에 대하여 자세하게 소개하고 특징 및 장 단점을 설명하였으며, 자동차 부품군에로의 적용에 많은 이점들을 갖고 있음을 설명하였다. 두 번째로는 가변단면 압출을 위한 이동 금형(Moving die)부품을 갖는 구조의 압출금형에 관하여 기존의 압출금형과 비교하여 설명하였으며, 가변단면 압출용 금형의 구조 및 메커니즘의 최적화를 이루고자 하였다. 세 번째로는 가변단면 압출공정을 실현하기 위한 CNC 제어 압출시스템에 대하여 간략히 설명하였다. 네 번째로는 자동차 부품 적용을 위한 정밀 압출공정으로서 가변단면 압출공정에 대하여 유한요소해석을 통하여 가변단면 압출공정 변수 및 금형 변수 등에 대한 엄격한 검토를 선행적으로 수행하여 양산성 확보를 위한 정보들을 분석 정리하였다. 끝으로는 세 가지 단면형태를 갖는 가변단면 압출제 시제품에 대하여 CNC 제어 가변 단면 압출공정의 상용화 가능성을 확인 적용성 검토를 완료하였다. CNC 제어 가변단면 압출기술은 압출공정에 있어서 많은 경험과 기술적 검토가 선행되어져야 하는 고부가가치 성형공정으로써 재료 이용률을 획기적으로 향상시킬 수 있는 압출공법으로 향후 자동차 부품 뿐만아니라 다양한 알루미늄 제품군에 적용이 가능하다고 판단된다.

• Geomechanics and Engineering
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• v.8 no.4
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• pp.541-557
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• 2015

This research aims to analyze the fracture coalescence characteristics of brittle sandstone specimen ($80{\times}160{\times}30mm$ in size) containing various flaws (a single fissure, double squares and combined flaws). Using a rock mechanics servo-controlled testing system, the strength and deformation behaviours of sandstone specimen containing various flaws are experimentally investigated. The results show that the crack initiation stress, uniaxial compressive strength and peak axial strain of specimen containing a single fissure are all higher than those containing double squares, while which are higher than those containing combined flaws. For sandstone specimen containing combined flaws, the uniaxial compressive strength of sandstone increase as fissure angle (${\alpha}$) increases from $30^{\circ}$ to $90^{\circ}$, which indicates that the specimens with steeper fissure angles can support higher axial capacity for ${\alpha}$ greater than $30^{\circ}$. In the entire deformation process of flawed sandstone specimen, crack evolution process is discussed detailed using photographic monitoring technique. For the specimen containing a single fissure, tensile wing cracks are first initiated at the upper and under tips of fissure, and anti-tensile cracks and far-field cracks are also observed in the deformation process; moreover anti-tensile cracks usually accompanies with tensile wing cracks. For the specimen containing double squares, tensile cracks are usually initiated from the top and bottom edge of two squares along the direction of axial stress, and in the process of final unstable failure, more vertical splitting failures are observed in the ligament region. When a single fissure and double squares are formed together into combined flaws, the crack coalescence between the fissure tips and double squares plays a significant role for ultimate failure of the specimen containing combined flaws.

• Journal of the Korean Solar Energy Society
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• v.37 no.1
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• pp.1-14
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• 2017

A series of coupled time domain simulations considering stochastic waves and wind based on five 1-h time-domain analyses are performed in normal operating conditions. Power performance and tower base Fore-Aft bending moment and pitching motion response of the floating spar-buoy wind turbine with 2 MW direct-drive PMSG have been analyzed by using HAWC2 that account for aero-hydro-servo-elastic time domain simulations. When the floating spar-buoy wind turbine is tilted in the wind direction, maximum of platform pitching motion is close to $4^{\circ}$. Statistical characteristics of tower base Fore-Aft bending moment of floating spar-buoy wind turbine are compared to that of land-based wind turbine. Maximum of tower base Fore-Aft bending moment of floating spar-buoy wind turbine and land-based wind is 94,448 kNm, 40,560 kNm respectively. This results is due to changes in blade pitch angle resulting from relative motion between wave and movement of the floating spar-buoy wind turbine.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.197-202
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• 2016

In this paper, we propose optimal smart home security monitoring system. Proposeed optimal smart home security system using the three types of ultrasonic sensors were tested to obtain reliable data. and Using Raspberry Pi3, the smart home security system was implemented. In addition, It was verified through experiments optimal efficiency with a small amount compared to the conventional sensor of the home security system by the two ultrasonic sensors located in the optimal position. It was able to use two ultrasonic sensors to determine whether the intruder's highly efficient and reliable intrusion, and connect the servo motor at the bottom of the camera so you can shoot adjusted to the attacker's location to shoot the intruder's image. In addition, by using a Web server and stored the recorded image and two ultrasonic sensor data and provide a Web page for a user to monitor at all remote locations.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.274-283
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• 2006

The Permanent Magnet Synchronous Motor(PMSM) drive systems with ball-screw, gear and timing-belt are widely used in industrial applications such as NC machine, machine tools, robots and factory automation. These systems have torsional vibration in torque transmission from servo motor to mechanical load due to the mechanical couplings. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the mechanical plant. This paper presents adaptive notch filter with auto searching function of vibration frequency to reject the mechanical vibration of linear feeder system with PMSM. The proposed adaptive notch filter can suppress the torque command signal of PMSM in the resonant bandwidth for reject the mechanical torsional vibration. However, the resonant frequency can vary with conditions of mechanical load system and coupling devices, adaptive notch filter can auto search the vibration frequency and suppress the vibration signal bandwidth. Computer simulation and experimental results shows the verification of the proposed adaptive notch filter in linear feeder system with PMSM.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.534-539
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• 2008

This paper is about intelligent hexapod robot for the support walking of the aged person. The robot using various sensors and small camera has various abilities of forward backward walking, turing left or right, control the speed of walking, avoiding the obstacles and detecting risky situation of fire or gas. To let the aged feel soft and safe walking, we used special servo motor and developed hexapod walking mechanism and effective algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.248-253
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• 2015

In order to adapt to human's life and perform missions, a humanoid robot needs a height at least similar with children's. In this paper, we proposed a humanoid robot which is like a child who is taller than 1m. We presented showing the humanoid robot's kinematics, designing of a three-dimensional model, developing mechanisms, and the hardware structures using servo motors and compact size PC. Through this process, we designed and manufactured child humanoid robot 'CHARLES(Cognitive Humanoid Autonomous Robot with Learning and Evolutionary Systems)' that is robot is 1m 10cm tall and 8.16kg in weight. For robot's walking, we applied to ZMP-based walking technique and the creation algorithm is applied for walking patterns. Through experiments, we analyzed walking patterns according to the creation and changing parameter values.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.437-442
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• 2014

Recently, the needs for the development and application of the micro marine robot (MMR) which has the advantages in terms of size and cost are increasing. However, the basis is very short in the domestic. While the obstacle avoidance sonar (OAS) which was optimized in terms of size and performance and has the ability of 4-directional detection was developed for the obstacle avoidance of the micro surface robot (MSR) fortunately, the problem that the detection performance is degraded according to the shape of the obstacle because of using the fixed sonar-beam with the limited beam width and detection range exists. To solve this problem, the MSR mechanism that implements the rotating sonar-beam using the spur gear and the servo motor is proposed in this paper. To verify the performance of the proposed mechanism, the wall-tracking of the MSR is considered and the comparison and analysis in term of detection performance and actuation command is performed with conventional fixed sonar-beam. The test results show the validity of the proposed mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.431-438
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• 2016

Recently, concerns about the environment are becoming more important because of global warming and the exhaustion of earth's resources. In the aviation and automobile industries, the application of light materials is increasingly important for eco-friendly and effective. Carbon Fiber Reinforced Plastics is a composite material which great formability and the high strength of carbon fiber. CFRP, which is both light and strong, is hard to manufacture. In addition, CFRP machining has a high chance of defects. This research discusses the development of a manufacturing system package for CFRP machining. It involving CFRP Drilling/Water-jet Manufacturing Machines, Inspection/Post-processing Systems, CNC platform for an EtherCAT servo Communication, Flexible Manufacturing Systems and CFRP machining Processes.