• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.730-735
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• 2004

Nowadays, most small form-factor drives adapt a load/unload mechanism and the flying height of the head becomes more and more low. So, the load/unload velocity also becomes one of the important factors to ensure the reliability of the load/unload operation. To control the load/unload velocity accurately, velocity sensing is most important because there is no special velocity sensor during the load/unload operation. In this paper, we proposed a very practical method that measures the velocity from the BEMF voltage of a VCM. Then, the proposed method is applied to the load/unload velocity control using 2.5' drives in order to verify its usefulness.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.68.5-68
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• 2002

For the performance test of rechargeable electric tools, it is necessary to test under the same condition as the actual operation condition. They are necessary to control the load torque and to acquire the test data with a computer, and it should be convenient to fix the tool on the test equipment for rechargeable electric tools. It consists of torque loading parts, sensing parts and control software. Two hysteresis brakes, connected serially with flexible coupling, were applied to control the load for the test. The sensing part consists of a torque sensor, a rpm detector and a power analyzer. The torque and the rpm were measured in order to calculate the output of the rechargeable electric...

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.335-342
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• 2000

A new control method for a single-phase active power filter, based on a load current estimation using a DC capacitor voltage of active power filter without sensing nonlinear load current, is proposed in this paper. Because the method proposed can remove the load current sensor in comparison with a conventional method sensing the load current and DC capacitor voltage together, it can make the active power filter easy installation, low cost, small size with no performance detriment. In addition, sample-hold technique and proportional control method is adopted to control the DC capacitor voltage and as no delay element such as LPF or PI control in the conventional method is used, the transient response is fast and good. Operation of a single-phase active power filter which consist of eight mode is explained according to utility voltage, compensation current and switch state, and compensation characteristics of active power filter using proposed method is verified by experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.4
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• pp.53-61
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• 1988

Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.50-56
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• 2006

Since most of small form-factor drives have a load/unload mechanism and the flying height of the head is getting lower as the capacity of disk drives increases, the load/unload velocity becomes one of the important factors to ensure the reliability of the load/unload mechanism. To control the load/unload velocity accurately, velocity sensing is essential. In this paper, we introduce a very practical method that acquires the load/unload velocity from the back electromotive force (BEMF) of a voice coil motor (VCM) and propose a calibration method for measuring the BEMF from a given circuit. Moreover, the effect of calibration error and temperature variation on the measurement of BEMF is shown by simulation. Then, this present method is applied to the load/unload velocity controller and is verified from the experimental result.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1934-1937
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• 2005

This paper proposes suitable gait generation for dynamic walking of biped robot with varying load in real time. Author proposes the relationship between ZMP(Zero Moment Point) and measurement from FSR(Force Sensing Register). Simplifying this relationship, it is possible to reduce the computational time and control the biped robot in real time. If the weight of the biped robot varies in order to move some object, then joint trajectories of the the biped robot must be changed. When some object is loaded on the biped robot in it's home position, FSRs can measure the variation of weight. Evaluating the relations between varying load and stable gait of the biped robot, it can walk adaptively. This relation enables the biped robot to walk properly with varying load. The simulation is also represented in this paper which shows proposed relationships.

• Proceedings of the KIPE Conference
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• 2004.11a
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• pp.85-89
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• 2004

This paper presents Power Control and Distribution Unit development of GEO satellite with 3kW power output. The sensing error of bus voltage produce control signal of the shunt switch assembly and battery power converter, and the tolerance of error signals generated decide the stability of proposed system. The dynamic characteristics of main bus according to the load changing and the control logic of FPGA are simulated. In order to verify the proposed design, the simulation and experimental results for solar array shunt switch, battery power converter and bus controller are shown.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.850-856
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• 2001

Even though the hydraulic servo system has been widely used in industrial and military equipments since it has a lot of advantages, it is not easy to design controller due to the high nonlinearities and the parametric uncertainties. The dynamic behavior of the real process in the hydraulic servo system differs from that described by its model because the model is linearized. Another reason of the difference is caused by the variety of parameters, since the system parameters of the dynamic equation are affected by the operating conditions such as temperature and pressure. In this study, the designing process of the MRNC with a PID compensator is introduced and applied to the load sensing hydraulic servo system. The results show that the designed controller guarantees the robust control performance despite of both the nonlinearities and the parametric uncertainties.

• Smart Structures and Systems
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• v.13 no.6
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• pp.993-1014
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• 2014

In civil engineering, revolving structures (RS) are a unique structural form applied in innovative architecture design. Such structures are able to revolve around themselves or along a certain track. However, few studies are dedicated to safety design or health monitoring of RS. In this paper, a wireless dynamic sensing system is developed for RS, and field tests toward a large revolving auditorium are conducted accordingly. At first, a wheel-rail problem is proposed: The internal force redistributes in RS, which is due to wheel-rail irregularity. Then the development of the sensing system for RS is presented. It includes system architecture, network organization, vibrating wire sensor (VWS) nodes and online remote control. To keep the sensor network identifiable during revolving, the addresses of sensor nodes are reassigned dynamically when RS position changes. At last, the system is mounted on a huge outdoor revolving auditorium. Considering the influence of the proposed problem, the RS of the auditorium has been designed conservatively. Two field tests are conducted via the sensing system. In the first test, 2000 people are invited to act as the live load. During the revolving process, data is collected from RS in three different load cases. The other test is the online monitoring for the auditorium during the official performances. In the end, the field-testing result verifies the existence of the wheel-rail problem. The result also indicates the dynamic sensing system is applicable and durable even while RS is rotating.

• ETRI Journal
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• v.37 no.6
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• pp.1154-1164
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• 2015

This paper proposes a fully sensorless driver for a permanent magnet synchronous motor (PMSM) integrated with a digital motor controller and an analog pre-driver, including sensing circuits and estimators. In the motor controller, a position estimator estimates the back electromotive force and rotor position using a sliding-mode observer. In the pre-driver, drivers for the power devices are designed with a level shifter and isolation technique. In addition, a current sensing circuit measures a three-phase current. All of these circuits are integrated in a single chip such that the driver achieves control of the speed with high accuracy. Using an IC fabricated using a $0.18{\mu}m$ BCDMOS process, the performance was verified experimentally. The driver showed stable operation in spite of the variation in speed and load, a similar efficiency near 1% compared to a commercial driver, a low speed error of about 0.1%, and therefore good performance for the PMSM drive.