• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.987-992
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• 1992

In recent years, induction motor is applied for several industrial actuatung parts instead of direct current motor because of the robust construction, nonexpensive and maintenance-free actuator etc. and having capability of speed control according to development of power electrounics and microprocessor techniques. In the paper, a microprocessor-based digital control approach for spped control of induction motor system is presented by considering a simple modelling equation as the system expression equation of induction motor and using the self tuning control and torque effdforward control method. As the model equation of the induction motor system, we use a second order differential equation which is well known in the modeling equation is induced form the control theory stand point such tath we can describe usually the motor system connected by inverter, generator and load etc. The effectiveness of the control system composed by the above mentioned design concept is illustrated by the expermental result in the presence of step reference change and generator load variation.

• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.264-272
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• 1998

This paper proposes a fault detection and recovery mechanism for a fault-tolerant Mini-MAP system, and provides detailed techniques for its implementation. This paper considers the fault-tolerant Mini-MAP system which has dual layer structure from the LLC sublayer down to the physical layer to cope with the faults of those layers. For a good fault detection, a redundant and hierarchical fault supervision architecture is proposed and its implementation technique for a stable detection operation is provided. Information for the fault location is provided from data reported with a fault detection and obtained by an additional network diagnosis. The faults are recovered by the stand-by sparing method applied for a dual network composed of two equivalent networks. A network switch mechanism is proposed to achieve a reliable and stable network function. A fault-tolerant Mini-MAP system is implemented by applying the proposed fault detection and recovery mechanism.

• 한국전자통신학회논문지
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• 제18권3호
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• pp.459-464
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• 2023

본 논문은 태양광을 이용하여 에너지를 발전하여 생성되는 전력으로 각종 센서 및 환경 모니터링이 가능하도록 계통 독립형 전력을 공급한다. 생산된 잉여 전력은 리튬 배터리에 저장시켜 태양광이 없는 환경에서도 컨테이너 하우스가 원활한 구동이 가능하도록 설계하였다. 긴 장마나 폭설로 인하여 태양광 생성이 어려우면 디젤발전으로 시스템이 멈추지 않고 구동할 수 있도록 하였다. 태양광 및 전력 관리를 위해 BMS(Battery Management System)를 구축하여 태양광 방/충전 및 사용량을 모니터링한다. 각종 센싱 데이터를 자동으로 기록하고 전송되며, 컴퓨터 및 스마트폰 앱을 통해 무선 모니터링이 가능하도록 설계하였다. 본 연구에서 제안하는 컨테이너 하우스는 계통 전원이 없는 오지, 공원, 행사장, 공사현장 등에서 최적의 에너지 운영을 수행함으로써 효율적인 에너지 관리가 가능하다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.719-720
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• 2004

A multi-megawatt long pulse ion source (LPIS) of neutral beam injector was developed for the KSTAR. Beam extraction experiments of the LPIS were carried out at the neutral beam test stand (NBTS). Design requirements for the ion source were 120 kV/65 A deuterium beam and a 300 s pulse length. A maximum ion density of $9.1310^{11}$ $cm^{-3}$ was measured by using electric probes, and an optimum arc efficiency of 0.46 A/kW was estimated with ion saturation current of the probes, arc power, and total beam area. An arcing problem, caused by the structural defect of decelerating grid supporter, in the third gap was solved by the blocking of backstream ion particles, originated from the plasma in the neutralizer duct, through the unnecessary spaces on the side of grid supporter. A maximum drain power of 1.5 MW (i.e. 70 kV/21 A) with hydrogen was measured for a pulse duration of 0.5 s. Optimum beam perveance was ranged from 0.75 to 0.85. An improved design of accelerator for the effective control of beam particle trajectory should provide higher beam perveance.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.765-768
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• 2003

In the end of a production line a new built power converter has to undergo a series of stress tests. This can be achieved by connecting it to a dynamometer consisting of a three-phase machine joined by a rigid shaft to a DC load machine. The latter is controlled to create some specific load characteristic needed for the test. In this paper a test method is proposed, in which no mechanical equipment is needed. The suggested test stand consists only of a converter to be tested and a simulator converter. Both devices are connected back-to-back on the AC-side via smoothing reactors. The simulator operates in real-time as an equivalent load circuit, so that the device under test will only notice the behaviour of a three-phase machine under consideration of the load.

• 전기학회논문지P
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• 제57권2호
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• pp.202-208
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• 2008

Condition monitoring technologies allow achieving this goal by minimizing downtime through the integrated planning and scheduling of repairs indicated by condition monitoring techniques. Thermal runaways induced by conduction problems deteriorate insulating material and cause disruptive dielectric discharges resulting in arcing faults. Therefore, having the ability to directly measure the temperature of the contacts while in service will provide more information to determine the true condition of the equipment. It allows connective measures to be taken to prevent upcoming failure. Continuous temperature monitoring and event recording provides information on the energized equipment's response to normal and emergency conditions. On-line temperature monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the monitored equipment and optimize facility operations. Using wireless technique eliminates any need for special cables and wires with lower installation costs if compared to other types of online condition monitoring equipment. In addition, wireless temperature monitoring works well under difficult conditions in strategically important locations. Wireless technology for on -line condition monitoring of energized equipment is applicable both as stand alone system and with an interface for power quality monitoring system. The paper presents the results of wireless temperature monitoring: of electrical equipment at a power plant.

• 조명전기설비학회논문지
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• 제24권5호
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• pp.129-135
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• 2010

화석에너지의 고갈과 환경오염 문제를 해결하기 위한 대안인 신재생 에너지를 이용하는 분산발전 시스템은 핵심 구성 요소인 PWM 인버터의 전력제어가 요구된다. 본 논문에서는 단상 계통연계 인버터 시스템의 전력제어를 위해 계통 임피던스를 고려한 SRF(synchronous-reference-frame) 전력제어 방법을 제안한다. 제안한 SRF 전력제어 방법은 복잡한 계통 임피던스의 추정 없이 계통 임피던스의 공칭값(nominal value)에 기반해 단상 인버터에 전압 기준값(reference)을 제공하여 독립운전 모드와 계통연계 모드에서 모두 운전이 가능함을 나타내었다. 또한, 유효전력과 무효전력의 독립적인 제어가 가능한 장점을 가진다. 계통을 포함하는 시뮬레이션을 통해 제안한 SRF 전력제어 방법의 타당성을 검증한다. 시뮬레이션 결과는 제안한 SRF 전력제어 방법을 통해 단상 계통연계 인버터 시스템의 전력 흐름을 적절히 제어할 수 있음을 보여주고 있다.

• Nuclear Engineering and Technology
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• 제36권4호
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• 비파괴검사학회지
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• 제32권6호
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• pp.661-668
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• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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• pp.80-85
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• 2008

A PVIB(Photovoltaic in Building) system is united by a constituent outer covering and can expect dual effects that reduce expenses for the establishment of a PV system. It is a profitable technology because it does not need a building as it is a stand alone PV system. This paper presents design, operational features analysis, and PCS(Power Conditioning System) of grid-connected 30kW PVIB set up on the library of Dongshin University. For a sustainable photovoltaic system in this area, the data of the PVIB system are collected and analyzed by monitoring system using LabView. PCS of the grid-connected PVIB system, also, is designed for optimal operation with characteristics suggested in this paper.