• Journal of Broadcast Engineering
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• v.25 no.4
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• pp.497-506
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• 2020

A chameleonic surface proposed in this study was a pin-art and 3D display device for generating arbitrary shapes. A smooth and continuous surface was formed using slim telescopic actuators and high-elasticity composite material. Realistic 3D shapes were continuously generated by projecting dynamic mapping images on the surface. A slim telescopic actuator was designed to show long strokes and minimize area for staking. A 3D shape was formed by thrusting and extruding the high-elasticity material using multiple telescopic actuators. This structure was advantageous for generating arbitrary continuous surface, projecting dynamic images and lightening weight. Because of real-time synchronization, a distributed controller based on EtherCAT was applied to operate hundreds of telescopic actuators smoothly. Integrated operating software consecutively generated realistic scenes by coordinating extruded shapes and projecting 3D image from multiple projectors. An opera content was optimized for the chameleon surface and showed to an audience in an actual concert.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3173-3185
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• 1996

Multi-model vibration control of laminated composites plates for various fiver orientations has been carried out by making use of piezolectric materials(PZT) as sensors and actuators. Cantilever plate is used as a specimen to test multi-modal vibration supression under random exitation. Impulse technique is applied to determine the natural frequency, the damping ratio(.zeta.) and the modal damping(2.zeta..omega.) of the first bending and the trosion modes. Two independent controllers are implemented to control the two modes simultaneously and established digitally on the basis of the direct negative velocity feedback control with collocated sensor/actuator. Experimental results for various fiber orientations and feedback gains are compared with finite element analysis considering stiffnesses and dampings of piezoeletiric sensors, actuators and bonding layer.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.83-89
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• 2008

This paper presents the dynamic analysis and input shaping control of a positioning stage. Vibration characteristics of the positioning stage are affected not only by the structural dynamics but also by the servo actuators that consist of the mechanism; driving motor and controller. This paper proposes an integrated dynamic model to accommodate both the structural dynamics and the servo actuators. Theoretical modal analysis with a commercial finite element code is carried out to investigate the dynamic characteristics of the experimental positioning stage. Experiments are performed to validate the theoretical modal analysis and estimate the equivalent stiffness due to the servo actuators. This paper deals with an input shaping scheme to suppress vibration of the positioning stage. Input shapers are systematically implemented for the positioning stage in consideration of its dynamics. The effects of servo control gain are also investigated. The experiments show that input shaping effectively removes residual vibrations and then improves the performance of positioning stage.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.482-490
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• 2023

With the advent of the Fourth Industrial Revolution, many companies are developing Smart Ships to enable autonomous navigation, unmanned operation, and cost-effective shipping. In order to facilitate the operation of these Smart Ships, significant emphasis is being placed on improving external communication capabilities and developing autonomous navigation systems. Moreover, unmanned ship operation necessitates replacing of all visually observed conditions with sensors, leading to an inevitable increase in the number of sensors and actuators compared to traditional methods. However, in South Korea, the communication network for sensors and actuators primarily relies on the conventional 1:1 hardwired wiring, with the use of higher-level communication networks when necessary. Therefore, in this paper, we introduce the AS-Interface protocol, which is used for monitoring and controlling sensors and actuators, with the expectation that it will greatly contribute to the development of future Smart Ships by reducing production time, costs, and maintenance duration.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.190-197
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• 2011

In industrial distributed control systems, sensors collect data from the physical environment periodically and transmit them to the actuators, which process the control operations based on the received data. For the effective operation of the control systems, the data transmitted by the sensors has to be delivered to the actuators reliably within the deadline, and if the message reception rate of the actuators becomes lower than a threshold, then the performance of the control systems drops greatly. This paper suggests a message routing protocol to transmit periodic messages reliably in a distributed control system based on wireless sensor networks. For reliable message transmission, the proposed protocol selects a routing path whose end-to-end message reception rate is the highest before transmitting data messages. The proposed protocol has the capability of maintaining a target message reception rate for each flow. To maintain the required target reception rate, each destination monitors the actual message reception rate periodically and transmits a feedback message to the source if it drops below the target reception rate. On receiving the feedback message, the source tries to find a new path which can satisfy the target rate. The performance of the proposed protocol has been evaluated using simulation and compared with other protocols in terms of the message reception rate, the message delay and delay jitter, and so on. The simulation results show that the proposed protocol has a higher message reception rate and comparable message delay and delay jitter to other protocols. The simulation results also show that the proposed protocol has an ability to adapt well to the dynamic network traffic change.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.73-77
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• 2004

This paper presents a PC-based controller of industrial SFFS(Solid Freeform Fabrication System). The SFFS has multiple sub-controllers for the building room, the powder room, the temperature, and the density of oxygen in the chambers. Hence the main PC-based controller should effectively and timely send commands to the sub-controllers, and monitor the overall SLS process. The required actuators and sensors are selected to optimize the overall performance of the SFFS.

• 대한공업교육학회지
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• v.34 no.2
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• pp.396-410
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• 2009

The goal of this work is to present an advanced method of an estimation of the Modeling Uncertainties coming up in industrial rigid robot's manipulator and actuators. First, with the given physical robot model, the motion equation was derived. Considering a fictitious model, a new extended motion equation is developed. Based on this extended model, an observer and observer bank are designed for the estimation of modeling uncertainties which are involving the effects of gravity, friction, mass unbalance, and Coriolis which show the nonlinear characteristics in operation states.

• Prospectives of Industrial Chemistry
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• v.24 no.6
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• pp.19-31
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• 2021

자극응답성 액정 엘라스토머(liquid crystal elastomer)는 하이드로겔(hydrogel), 형상 기억 고분자(shape memory polymer)와 더불어 생체 특성을 모방한 인공 근육, 소프트 액추에이터 및 소프트 로봇을 위한 스마트 소재로 최근 높은 관심을 받고 있다. 특히, 액정 엘라스토머는 고무 탄성과 액정 이방성이 결합된 비등방성 탄성 고분자로, 열, 빛, 전기 및 수분과 같은 외부자극에 반응하여 가역적이며, 액정 분자들의 배향조절을 통한 프로그램된 변형이 가능하다. 액정 엘라스토머가 개념 증명을 하는 수준을 넘어 실제로 유용한 소프트 액추에이터 및 로봇 시스템에 적용되기 위해서는 우수한 구동력 및 작업 용량, 높은 구동 변형률, 빠른 응답 시간, 낮은 구동 온도, 다양한 외부 자극반응성 및 높은 에너지 전환 효율 등을 확보하는 것이 중요하다. 본 기고문에서는 액정 엘라스토머의 개념에 대해 소개하고, 이러한 소재가 소프트 액추에이터로써 광범위하게 활용될 수 있도록 다양한 성능들을 향상시킬 수 있는 방법에 대해 소개하고자 한다.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.161-171
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• 2002

This paper presents a linear motor, which generates large thrust with a low operating rate. In industrial fields there is a need for actuators that work with a low duty cycle but generate large thrusts. An example of such a case is provided by the actuators for ejector mechanisms in electric injection molding machines. The ordinary LSM (linear synchronous motor) is unsuitable for this large-thrust and low-operating-rate usage, because of its large size and high cost. This paper contains experimental results on linear motors that can generate large thrusts for a short time, and which can be cheaply produced. The described linear motor could be contained space of $250mm \times250mm\times 250mm$ and generate a maximum thrust of about 20000 N at a current of 250 A.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.1-5
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• 2011

Electronics in modern life have become more miniaturized and precise and new technology of electronic components has made these trends possible. The explosive demand of electronic components needs more high-speed and accurate performance of manufacturing processes. For high-speed actuation, solenoids, voice coil motors and piezo motors have been used. A solenoid actuator characterized by low price, available small size, and convenience is one of the main components of production equipments requiring compact and high-speed actuators. Since these actuators show millisecond order responsiveness, the improvement of 1~2msec is very important in industrial applications. In this paper, the mathematical model of the solenoid is formulated and simulated using SIMULINK$^{(R)}$. To verify the model, the responses for step input with open-loop control is obtained and compared with the simulation result. In order to improve the responsiveness, Hold voltage method is introduced and optimal value between spring constant and hold voltage is suggested.