• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2147-2150
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• 2003

Recently, many technologies of the P.L.C (Power Line Carrier) are introduced for an efficient communication. P.L.C communication sends information in the carrier signals by conduction over the power wire. An arc detector is proposed in this paper for the effective transmission. The Power Line Carrier has an advantage in low cost because it uses existent power line. It can be easily applied anywhere that a power line socket is available. But the P.L.C. is very noisy, because many electronic devices in generate electronic noise in modulated signals. This problem should be considered carefully in the design of the arc detector system using P.L.C in railway. The proposed system can be applied for monitoring the arc detector system and the arc locator system in railway. Hence the system will be able to exchange the arc information to be T.C.M.S. (Train Control Management System), bogies and even between a station and trains in railway and use to suspicion fire in train.

• 한국멀티미디어학회논문지
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• 제11권5호
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• pp.641-650
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• 2008

휴대 기기의 보급 확대에 따라 작은 배터리의 사용 시간 연장을 위해 배터리의 전력 관리 기법이 필요하다. 기존의 전력 관리 기법들은 전압 변경에 따른 오버헤드를 고려하지 않거나 부분적으로 고려하였다. 따라서 전압 변경 오버헤드는 개인용 멀티미디어 시스템의 실시간 태스크의 스케줄을 보장 못하는 경우가 발생할 수 있다. 본 논문은 전압 변경 오버헤드를 고려하면서 시스템의 이용률 정보를 바탕으로 사용 가능한 주파수의 개수와 연속된 주파수 사이의 간격을 조절하여 소비 전력을 줄이는 전력 관리 알고리즘을 제안한다. 본 알고리즘은 주파수 변경 회수를 줄여 기존의 CC RT-DVS 방법과 smoothing 방법에 비해 10에서 25%정도 소비 전력을 절감할 수 있다.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.927-933
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• 2014

CN(Communication Network)기반의 선박 전력관리 시스템은 선박의 안정적인 항해를 위한 가장 중요한 필수요소이다. 따라서 대부분의 선박은 안전을 목적으로 맥동 부하에 대응하기 위해 필요 용량보다 더 큰 용량의 발전기를 설치한다. 하지만 이러한 비교적 큰 용량의 발전기는 낮은 전력부하에서 발전기의 저부하 손실과 효율을 감소시키는 단점을 지니고 있다. 이에 따라 본 논문에서는 선박의 맥동부하를 방지하기 위한 보조전력을 적용한 하이브리드형 전력시스템을 제안하며, 전력시스템 설계를 위해 실 선박의 운항 데이터를 바탕으로 NI사의 LabVIEW를 이용하여 시뮬레이션을 진행하였다. 시뮬레이션을 통하여 안전항해를 위한 보조전력시스템과 연계한 하이브리드형 전력시스템의 적용방안을 제안한다.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3361-3379
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• 2022

A nuclear power plant (NPP) piping is designed against low-frequency earthquakes. However, earthquakes that can occur at NPP sites in the eastern part of the United States, northern Europe, and Korea are high-frequency earthquakes. Therefore, this study conducts bi-directional shaking table tests on actual-scale NPP piping and studies the response characteristics of low- and high-frequency earthquake motions. Such response characteristics are analyzed by comparing several responses that occur in the piping. Also, based on the test results, a piping numerical analysis model is developed and validated. The piping seismic performance under high-frequency earthquakes is derived. Consequently, the high-frequency excitation caused a large amplification in the measured peak acceleration responses compared to the low-frequency excitation. Conversely, concerning relative displacements, strains, and normal stresses, low-frequency excitation responses were larger than high-frequency excitation responses. Main peak relative displacements and peak normal stresses were 60%-69% and 24%-49% smaller in the high-frequency earthquake response than the low-frequency earthquake response. This phenomenon was noticeable when the earthquake motion intensity was large. The piping numerical model simulated the main natural frequencies and relative displacement responses well. Finally, for the stress limit state, the seismic performance for high-frequency earthquakes was about 2.7 times greater than for low-frequency earthquakes.

• 한국정보통신학회논문지
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• 제23권8호
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• pp.923-929
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• 2019

자율운항선박의 기반은 추진시스템의 안정성이 중요하며, 추진체계의 안정성을 위하여 다중 발전 체계 및 추진체계를 갖추어야한다. 기존 선박에서는 안정성을 위하여 높은 발전 용량을 산정하며, 그 결과 저부하 운전으로 인한 경제성 하락을 야기한다. 이를 해결하기 위해서는 전력체계의 최적화를 통하여 발전 체계의 경량화와 효율의 증가가 필요하다. 본 논문에서는 전기추진선박용 OPMS(Optimization Power Management System)를 구축한다. OPMS는 하이브리드형 발전시스템, 에너지저장시스템, 부하제어시스템으로 구성된다. 발전시스템은 이중연료엔진, 에너지저장시스템은 배터리, 부하제어시스템은 추진 부하, 상용 부하, 불규칙 부하, 화물 기기 관련 부하, 갑판 부하로 구성된다. 각 시스템별 기기들의 특성에 대하여 모델링하여 전력체계를 구축하였다. 실험을 위하여 선박 운용에 따른 시나리오를 작성하고 안정성 및 경제성을 기존의 전기추진선박과 비교하였다. 실험의 결과 발전기의 비교적 적은 시간 투입으로 같은 전력량을 공급함으로써 선박의 LNG 1.3%, Main Fuel 0.3%, Pilot Fuel 35.1%의 연료소모량 감소를 통하여 경제성 및 안정성을 확인하였다.

• 한국지능시스템학회논문지
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• 제26권5호
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• pp.351-360
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• 2016

Rapid population growth with high living standards and high electronics use for personal comfort has raised the electricity demand exponentially. To fulfill this elevated demand, conventional energy sources are shifting towards low production cost and long term usable alternative energy sources. Hybrid renewable energy systems (HRES) are becoming popular as stand-alone power systems for providing electricity in remote areas due to advancement in renewable energy technologies and subsequent rise in prices of petroleum products. Wind and solar power are considered feasible replacement to fossil fuels as the prediction of the fuel shortage in the near future, forced all operators involved in energy production to explore this new and clean source of power. Presented paper proposes fuzzy logic based Energy Management System (EMS) for Wind Turbine (WT), Photo Voltaic (PV) and Diesel Generator (DG) hybrid micro-grid configuration. Battery backup system is introduced for worst environmental conditions or high load demands. Dump load along with dump load controller is implemented for over voltage and over speed protection. Fuzzy logic based supervisory control system performs the power flow control between different scenarios such as battery charging, battery backup, dump load activation and DG backup in most intellectual way.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2134-2143
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• 2018

This work introduces a fault diagnosis method for transformer based on self-powered radio frequency identification (RFID) sensor tag and improved Hilbert-Huang transform (HHT). Consisted by RFID tag chip, power management circuit, MCU and accelerometer, the developed RFID sensor tag is used to acquire and wirelessly transmit the vibration signal. A customized power management including solar panel, low dropout (LDO) voltage regulator, supercapacitor and corresponding charging circuit is presented to guarantee constant DC power for the sensor tag. An improved band restricted empirical mode decomposition (BREMD) which is optimized by quantum-behaved particle swarm optimization (QPSO) algorithm is proposed to deal with the raw vibration signal. Compared with traditional methods, this improved BREMD method shows great superiority in reducing mode aliasing. Then, a promising fault diagnosis approach on the basis of Hilbert marginal spectrum variations is brought up. The measured results show that the presented power management circuit can generate 2.5V DC voltage for the rest of the sensor tag. The developed sensor tag can achieve a reliable communication distance of 17.8m in the test environment. Furthermore, the measurement results indicate the promising performance of fault diagnosis for transformer.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1345-1356
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• 2021

Damage to nuclear power plants causes human casualties and environmental disasters. There are electrical facilities that control safety-related devices in nuclear power plants, and seismic performance is required for them. The 2016 Gyeongju earthquake had many high-frequency components. Therefore, there is a high possibility that an earthquake involving many high frequency components will occur in South Korea. As such, it is necessary to examine the safety of nuclear power plants against an earthquake with many high-frequency components. In this study, the shaking table test of electrical facilities was conducted against the design earthquake for nuclear power plants with a large low-frequency components and an earthquake with a large high-frequency components. The response characteristics of the earthquake with a large high-frequency components were identified by deriving the amplification factors of the response through the shaking table test. In addition, safety of electrical facility against the two aforementioned types of earthquakes with different seismic characteristics was confirmed through limit-state seismic tests. The electrical facility that was performed to the shaking table test in this study was a motor control center (MCC).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.370-372
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• 2005

Inconveniences which might arise in transmitting measured biological data based on cable protocols generally are recognized critical points in tele-monitoring environment and also restrict the mobility of the user. a. Especially, activity monitoring which is importantly recognized as a core parameter in ubiquitous healthcare arena and weight management, pervasive and wireless measuring technology is most needed. In this paper, we would like to suggest lower power, miniaturized communication system in order to solve the above problems. The suggested system is powered by small coin-size battery. Also, The suggested system is compared with a blue-tooth module which is generally available in the commercial market. Even though, the suggested system didn't have higher transmission rate, its low power consumption make the suggested system would be feasible in ubiquitous monitoring of biological signals in ubiquitous healthcare arena.

• Journal of Power Electronics
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• 제18권1호
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• pp.129-136
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• 2018

An accurate state-of-charge (SOC) estimation ensures the reliable and efficient operation of a lithium-ion battery management system. On the basis of a combined electrochemical model, this study adopts the forgetting factor least squares algorithm to identify battery parameters and eliminate the influence of test conditions. Then, it implements online SOC estimation with high accuracy and low run time by utilizing the low computational complexity of the unscented Kalman filter (UKF) and the rapid convergence of a particle filter (PF). The PF algorithm is adopted to decrease convergence time when the initial error is large; otherwise, the UKF algorithm is used to approximate the actual SOC with low computational complexity. The effect of the number of sampling particles in the PF is also evaluated. Finally, experimental results are used to verify the superiority of the combined method over other individual algorithms.