• International Journal of Precision Engineering and Manufacturing
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• 제4권4호
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• pp.13-18
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• 2003

This paper presents the in-process compensation to control cutter ronout and to improve the machined surface quality. Cutter ronout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by cutter ronout compensation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.453-460
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• 2002

Piezoelectric solids such as PZT and PLZT have been widely used as sensors or actuators for various smart structural systems. The main problem occurring in the applications is that a larger and larger actuation force is required to maximize the function of the system. This naturally leads to local concentrations of electric or stress fields near crack tips or geometric irregularities and thereby results in a nonlinear behavior of the system Hence, it becomes more important to Predict the nonlinear behavior of piezoelectric solids In this Paper we investigate the micro-mechanism of nonlinear behavior in piezoelectric materials and propose constitutive equations. The calculation results obtained from an associated finite element Program are shown to be qualitatively consistent with experiments.

• Nuclear Engineering and Technology
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• 제36권2호
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• pp.184-195
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• 2004

The multi-tasking feature of digital I&C equipment could increase risk concentration because the I&C equipment affects the actuation of the safety functions in several ways. Anticipated Transient without Scram (ATWS) is a typical case of safety function failure in nuclear power plants. In a conventional analysis, mechanical failures are treated as the main contributors of the ATWS. This paper quantitatively presents the probability of the ATWS based on a fault tree analysis of a Korea Standard Nuclear Power Plant is also presented. An analysis of the digital equipment in the digital plant protection system. The results show that the digital system severely affects the ATWS frequency. We also present the results of a sensitivity study, which show the effects of the important factors, and discuss the dependency between human operator failure and digital equipment failure.

• 동력기계공학회지
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• 제15권5호
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• pp.30-36
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• 2011

본 논문은 근수축을 이용한 근육 작용의 운동학을 다룬다. 첫째, 근육 해부학이 미시적 관점의 운동학에 대하여 검토되었으며, 다음으로 거시적 관점의 근육 운동학이 작동 이론을 설명하기 위해 공식화 되었다. 그리고 작동 모델을 평가하기 위해 시뮬레이션 결과가 제시된다. 본 연구는 마이크로미터 거리에 따라 생물학적 분자 운동이 어떻게 거시적 운동으로 바뀌는지를 설명하고 있다. 마지막으로 근육 모델이 거시적/미시적 작동용으로 여러 가지 역학의 형태로 이용될 수 있다는 것을 보인다.

• 한국정밀공학회지
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• 제12권11호
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• pp.125-131
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• 1995

Pneumatic System has been mainly used as main equipment for actuation and control of fluid force in manufacturing industry. For velocity control of piston, meter-out restriction method is used in many cases. In this systems, meter-out restriction method is adopted for analysing the Dynamic Charging and Discharging Process which is Variable Volume Chamber. Experiments has been conducted for different supply pressure condition. As a experimental result, charge side chamber pressure rises to supply pressure rapidily and discharge side chamber pressure decreases. Also, when the air in the cylinder is discharged, tempdrature of air decreases steeply. Restriction of the Cylinder sometimes freeze and it dose not function. The result will be useful for the analysis of pneumatic system.

• 항공우주산업기술동향
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• 제7권2호
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• pp.85-94
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• 2009

전투기에 처음 적용되었던 Fly-By-Wire (전자식 비행제어) 시스템은 여러 가지 장점으로 인해 까다로운 인증과정을 거쳐 민간 항공기에까지 적용되었고, 최근에는 소형제트기까지 적용 범위가 확장되고 있으며 미래에는 대부분 Fly-By-Wire 항공기가 주를 이룰 것으로 전망된다. 본 논문에서는 대형여객에서 소형제트기까지 민간 항공기에 적용되는 Fly-By-Wire 시스템의 구성 및 특성 등에 대하여 기술 하였다. 특히 비행조종컴퓨터 다중화 방안과 데이터 통신 버스, 조종면 작동기, Fly-By-Wire 시스템을 통하여 적용되는 제어 법칙 등에 대한 기술 개발 동향에 대해 고찰하였다.

• Steel and Composite Structures
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• 제31권4호
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• pp.341-359
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• 2019

Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

• 대한기계학회논문집A
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• 제31권11호
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• pp.1069-1076
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT(Quantitative Feedback Theory) is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. Tracking specification is satisfied with upper and lower bound tolerances on the steep response of the system to the reference signal. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• 대한기계학회논문집A
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• 제21권12호
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• pp.2081-2089
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• 1997

Accurate positioning of the throttle valve of a gasoline engine is required to implement various systems such as traction control system(TCS), cruise control system and drive-by-wire system. In this research, position control system has been developed for the throttle actuator system that uses one throttle actuation for small volume and DC servo motor for fast response. In order to drive the DC motor, PWM signal generator and PWM amplifier were built and interfaced to the motor and controller. Also, time delay control(TDC) law has been used as a basic control algorithm. A method of varying the reference model of the TDC according to the size of change in target throttle angle is proposed here. The simulation and experimental results show that both overshoot prevention and fast response are achieved by the TDC technique with this variable reference model.

• Journal of Biosystems Engineering
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• 제30권3호
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• pp.179-184
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• 2005

The purpose of this study was the development of teat-cup attachment module for robot milking system. The teat-cups attachment module was controlled on the two dimensional space independently, Each teat cup of an end effector was independently controlled via two axis control based on the position information data obtained from the image processing system. This system was developed install of all 4 teat cups at the same time after adjusting positions of each teat sequentially. The individual motion system was operated using two servo motors for the high speed of teat position adjustment. The errors fur the individual motion system of teat cups were maximum 1.0mm, minimum 0.0mm, and average 0.6mm. The operating time for adjusting the teat cups position required about 1.0 second. It is envisaged that teat cups attachment module can be applicate to milking robot being developed in consideration of the experiment results for the teat cups operation accuracy and the actuation speed of servo motors.