• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.20-27
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• 2022

This article aims to develop an algorithm that detects fire pump defects by analyzing the current signals of an induction motor, which are triggered by changes in the flow rate and pressure of multistage volute pumps that are used for fire services. The operational status of the pumps was categorized into three: first, normal operation; second, a defect that is caused by a change in the current value; and third, a defect occasioned by a change in current, pressure, and flow rate. When a fire pump was in normal operation, the motor's operating current was measured between 5.06 A and 6.9 A, the flow rate was estimated at 0-0.27 m³/min, and the pressure ranged from 0 to 0.47 MPa. In the event that a defect was caused by an abnormal current value in the motor, it was attributed to the pump's adherence. Furthermore, if there was no source of water, the defect was considered to have been induced by phase-loss operation, no-load operation, or run-stop operation, with the current value of each scenario being measured at > 52.8 A, < 4.13 A, > 45.15 A, and < 3.8 A, respectively, placing its overall range between 0 and 50 A. The sources of defects were detected based on an analysis of the flow rate, pressure, and current, which represent the following causes: air inflow into the casing, inadequate suction of water, and reverse-phase operation, respectively. Each cause entailed the following values: when air seeped into the casing, the pressure was measured at 0.24 MPa irrespective of changes in the flow rate; when there was inadequate suction of water, the pressure was recorded between 0 and 0.05 MPa despite changes in the flow rate; and when the power line's reverse-phase loss was the cause of the defect, the pressure was measured at 0.33 MPa for a flow rate of 0 L/min, and a higher flow rate decreased the pressure to nearly 0 MPa. The results of this study will enable engineers to develop a pump defect detection algorithm that is based on an analysis of current, and this algorithm will facilitate the execution of a program that will control a fire pump defect detection system.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.653-661
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• 2016

This paper proposes a capacitance estimation method of the dc-link capacitor for brushless DC motor (BLDCM) drive systems. In order to estimate the dc-link capacitance, the BLDCM is operated in quadrant-II or -IV among four-quadrant operation. Quadrant-II and -IV are called reverse braking and forward braking, respectively. During the braking operation of the BLDCM, the capacitor is charged by the phase current and then the voltage is increased during the braking operation time. The capacitor current and voltage can be obtained by using the phase current sensor of BLDCM and the dc-link voltage sensor. The capacitance and be easily obtained by the voltage equation of the capacitor. The proposed method guarantees the reliable and simple calculation of the dc-link capacitance without additional hardware system except several the sensors already installed for the motor control system. The effectiveness of the proposed method is verified through both the simulation and experimental results.

• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.82-91
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• 2004

This article deals with a minimum energy control law of S-CVT connected to a dc motor. The S-CVT can smoothly transit between the forward, neutral, and reverse states without any brakes or clutches, and its compact and simple design and its relatively simple control make it particularly effective for mechanical systems in which excessively large torques are not required. And such an S-CVT equipped power transmission has the advantage of being able to operate the power sources in their regions of maximum efficiency, thereby improving the energy efficiency of the transmission system. The S-CVT was intended to primarily for use in small power capacity transmissions, thus a dc motor was considered here as the power source. We first review the structure and operating principles of the S-CVT, including experimental results of its performance. And then we describe a minimum energy control law of S-CVT connected to a do motor. To do this, we describe the results of an analysis of the dynamics of an S-CVT equipped power transmission and the power efficiency of a DC motor. The minimum energy control design is carried out via B-spline parameterization. And we show numerical results obtained from simulations illustrate the validity of our minimum energy control design, benchmarked with a computed torque control algorithm for S-CVT.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.3
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• pp.7-12
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• 2007

This paper presents an energy saving hydrostatic pressure exchanger for sea water desalination equipment. In a reverse osmosis(RO) system for desalinating sea water, more than 70 percent of the supplied sea water, brines which were impassable through RO membrane are bypassed, resulting in high energy losses. In this paper, a hydrostatic pressure exchanger consisting of an embedded water hydraulic piston motor and a water hydraulic piston pump was proposed and investigated in order to recover the energy of the bypassed brines. The pressurized brines are supplied to the embedded water hydraulic piston motor as power sources and the water hydraulic piston pump is driven by the output torque of the embedded water hydraulic piston motor as well as electric motor. Consequently, the energy of the bypassed brines can be recovered. To examine the electric energy saving characteristics of the hydrostatic pressure exchanger, a simulation model was constructed using commercial software and experiments were conducted. Through the results of simulation and experiment, the feasibility of the electric energy saving effect of the proposed hydrostatic pressure exchanger was investigated.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.16-23
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• 2018

PM synchronous motor may be rotated to an arbitrary direction and speed by outside wind under natural condition in cases where the fan is applied outside, such as in vehicle radiators and outdoor air-conditioners. Sensorless controls that cannot detect rotor position requires additional sensorless control algorithm because a rotor is rotated by an external load. In this study, the sensorless control of a PM synchronous motor under naturally rotating condition is proposed. The natural rotation conditions are classified as forward high-speed rotation, reverse high-speed rotation, and low-speed rotation. Experiment results verify the performance of the sensorless control, including the rotor speed and position detection at natural rotation mode and switch to the closed-loop sensorless control.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.57-62
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• 2019

In this paper, oneM2M based data monitoring and acquisition system is designed and implemented to measure and transmit the voltage, current, temperature, acceleration and vibration of the motor. The proposed system can detect electrical faults (overcurrent, reverse phase, phase loss, ground fault) and mechanical faults (MC counter, motor operation time, bearing and winding temperature, motor speed, insulation resistance). The system consists of sensor data collection, web server, php, database, wired/wireless communication system. The insulation resistance and the motor speed were measured, and the experimental results were similar for both the test resistance value and the reference input value.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.237-243
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• 2002

A centrifugal compressor of 50HP for reverse brayton cryocooler using neon as a coolent has been developed. It has relatively low total-to-total pressure ratio but mass flow rate is very small and the voting gas, neon, has greater specific heat ratio than air. It was essential to have very high rotational speed of 100,000 RPM. The efficiency of compressor has great effects on overall system and the COP of cryocooler. To meet the design requirement of the compressor efficiency and to minimized the required rotational speed, highly efficiency impeller having low specific speed was designed. To maintain the overall system efficient high, gas bearing of bump type and high speed permanent magnet synchronus motor was developed and adopted. In this paper, design and performance prediction results of the compressor impeller is presented.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.287-289
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• 2011

본 논문은 인피니언 테크놀로지스의 RC-IGBT (Reverse Conducting Isolated Gate Bipolar Transistor)와 SOI 드라이브 IC(Integrated Circuit)를 사용한 DIL(Dual-In-Line) 구조의 저전력 모듈인 CIPOS TM (Control Integrated POwer System) 제품을 소개한다. 이 전력 모듈은 최적의 게이트 구동회로, 트렌치 필드스톱의 RC-IGBT를 사용하여 기존의 IGBT 와 Diode를 사용하는 구조에서 최소화 된 패키지 크기를 사용하여 높은 효율을 구현할 수 있다. 본 논문을 통하여 인버터의 어플리케이션에 적합하게 설계된 전력모듈에 대한 소개와 그 특징 및 시스템 구성을 위한 고려사항에 대하여 기술하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.3
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• pp.250-256
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• 1985

With the advant of thryistors having large peak inverse voltages, current-source inverters are becoming very popular to feed induction motors. But it is very difficult to analysis the commutation. Since the actual variation of current during commutation is neither instantaneous nor linear and is effected by many parameters. Minimized bias-time of reverse voltages during commutation is expressed in term of machine parameters, capacitor voltage, load current and so on. The minimized bias-time is computed with y and z and also the commuation mechanism is tested on 2.2 kw induction motor. The computed results are compared with the experimental results, and the results give a good information for designing the commutation mechanism.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.493-501
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• 2012

A rotational force generator for molten metal is developed using a linear motor design technology. Also, the developed device is applied to reproduce aluminum scraps and easy to control the rotate, stop, and forward and reverse rotation of molten metal. In addition, the developed device improves the melting speed and reproduction rate about 250 (%) and 96-99 (%), respectively, compared to the conventional handmade methods. Because it generates almost no dusts, it can improve working environments in a factory. Also, it has no losses in energy because it directly melts scraps. The device generates small amounts of the loss in refractory materials and aluminum caused by its oxidation because the molten metal is continuously rotated in which the loss and oxidized aluminum are the problems in the conventional melting and holding furnaces. Thus, it is possible to extend the life of furnaces and to produce high quality aluminum products.