• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.647-650
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• 2003

PLC (Power Line Communication) is the communication method using the existing power line installed in houses and offices to convert and transmit high frequency communication signal from tens of KHz to tens of MHz, and receive the filtered signal using high frequency filter The advantage of PLC is that PLC uses the existing power line installed in houses and offices so it does not require separate power line. Easy and convenient access using electric outlets is another advantage of PLC. However, PLC has some disadvantages such as limited transmission power, high load interference and noise, variable signal attenuation, characteristic of impedance, and selective possibility of frequency property. We designed the boiler temperature control system unit by using the PLC modem. We can avoid unnecessary heating of separate temperature control unit, and save the cost accordingly control stability of the proposed system is proven through the experiment.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.33-34
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• 2016

This paper presents a load sharing method based on the low bandwidth communication (LBC) applied to a DC microgrid in order to balance the state of charge (SOC) of the battery units connected in parallel to the common bus. In this method, SOC of each battery unit is transferred to each other through LBC to calculate average SOC value. After that, droop coefficients of battery units are adjusted according to the difference between SOC of each unit and average SOC value of all batteries in the system. The proposed method can effectively balance the SOC of battery units in charging and discharging duration with a simple low bandwidth communication system.

• International Journal of Railway
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• v.2 no.1
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• pp.22-29
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• 2009

A simple pendulum shows how efficient gravity is in recovering energy. Any transportation is a linearly oscillating system; every load gains kinetic energy, but loses the same to come to a stop. The Gravity Power Towers comprise of a set of vertically moving heavy masses coupled, through microprocessor controlled continuously variable gear and cable system, to a horizontally rolling unit on wheels either on rail or road. The heavy masses move vertically up against gravity gaining potential energy while stopping a moving mass; move down under gravity force, giving out energy. The Tower thus accelerates or sustains the speed a rolling unit, and while decelerating, recover the kinetic energy. Speeds of 360 kmph can be attained. Recovery of energy varies from 98.5-70%; the longer the distance between stops, the lesser is recovery. The economical, omnipresent & eternal Gravity Power grants energy independence to many a nation. Global warming reduces.

• Journal of Biosystems Engineering
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• v.37 no.4
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• pp.225-232
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• 2012

Purpose: Accurate monitoring of information from various agricultural vehicles is one of the most important factors for appropriate management strategy of field operations. While there has been a number of study and design on applications of sensors and actuators for data acquisition and control system in tractor, incompatibility between various customized hardware and software has become a major obstacle to the universal deployment in real field operation. International standard for implementation of electronic control unit (ECU) in agricultural vehicles has becoming a mandatory requirement for inter-operation compatibility in the international trade of agricultural vehicle industries. The ISO 11783 standard is basically based upon well known communication technology designated using the controller area network (CAN) bus. While CAN bus could provide 1.0 Mbps of communication speed, the standard only recommended 250 kbps. Methods: This study presents the implementation and evaluation of ISO 11783 for tractor electronic control units (TECU)with a higher transmission rate from multiple ECU than 250 kbps. Throughput and loss rate of the developed prototype were calculated across manipulated bus load for laboratory experimental tests, and the maximum requirement of transmission rate by ISO 11873 was satisfied with lower than 60% of bus load. Results: Field tests with a TECU implemented to process messages from global positioning system (GPS) receiver resulted that the root mean square error of position information was lower than 4 m with 0.5 m/s as a travelling speed. Conclusions: Results of this study represent the utilization of the international standard ISO 11783 to providepractical developments in terms with the inter-operability of TECU.

• Journal of Environmental Impact Assessment
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• v.17 no.1
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• pp.47-56
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• 2008

Total Maximum Daily Load(TMDL) is a core basin management system to assign total emissions of pollutants to unit basin and emission source within a limit of the target water quality and to secure sustainability. considering "Environment and development" together. By current technical guidance of TMDL, the water quality in the riverbed of which the target water quality is noticed, must achieve the target; and the water quality standard for evaluating achievement of the target should be prescribed as non-excessive probability quality of water on the basis of the pertinent water quality documents. Therefore, the study calculated the target water quality by each unit basin which the target water quality must be noticed through the analysis of probability for water quality documents in rivers at the time of establishing a plan, and the study evaluated the achievement possibility of the target water quality by analyzing and comparing the target water quality plan with the standard water quality to evaluate the achievement of the target water quality. As the result, applying the proposed method to Mihocheon River system, it is concluded that selected the target water quality (Each BOD 3.3mg/1 and BOD 3.0mg/1) in Miho A and Musim A is available. Of course, it showed that the target water quality: BOD 2.5mg/1 in Miho A and BOD 3.0mg/1 in Musim A, could be achieved if the small reduction in B unit area was implemented.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.481-493
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• 2009

This study was conducted to performance appraisal of Total Maximum Daily Loads (TMDLs), especially in terms of performance on development & reduction plan and water quality status of unit watershed. Because load allocations for pollution sources were predicted redundantly by uncertainty of prediction, TMDLs master plan has been frequently changed to acquire load allocation for local development. Therefore, It need to be developed more resonable prediction techniques of water pollution sources to preventing the frequent change. It is suggested that the reduction amount have to be distributed properly during the planning period. In other words, it has not to be concentrated on the specific year (especially final year of the planning period). The reason why, if the reduction amount concentrate on the final year of the planning period, allotment loading amount could not be achieved in some cases (e.g., insufficiency of budget, extension of construction duration). If the development plan was developed including uncertain developments, it is necessary to be developed reduction plan considered with them. However, some of the plans in the reduction plan could not be accomplished in some case. Because, it is not considered financial abilities of local governments. Consequently, development plan must be accomplished to avoid uncertain developments, and to consider financial assistance to support the implementation of effective plan. Water quality has been improved in many unit watersheds due to the TMDLs, especially in geum river and yeongsang/seomjin river.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.459-467
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• 2012

In this paper, a grid connected microgrid with multiple inverter-based distributed generators (DGs) is considered. DG in FFC mode regulates the microgrid as a controllable load from the utility point of view as long as its output is within the capacity limit. The transition mode causes a change in frequency of microgrid due to the loss of power transferred between main grid and microgrid. Frequency deviation from the nominal value can exceed the limit if the loss of power is large enough. This paper presents a coordinated control method for inverter-based DGs so that the microgrid is always regulated as a constant load from the utility viewpoint during grid connected mode, and the frequency deviation in the transition mode is minimized. DGs can share the load by changing their control modes between UPC and FFC and stabilize microgrid during transition.

• Journal of the Korea Society for Simulation
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• v.12 no.4
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• pp.51-59
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• 2003

Real-Time applications on Grid environment have several problems in terms of resource management addressed as follows; (1) dynamic resource allocation to provide QoS objectives, (2) heterogeneous resources that is different scale, or capacity in same unit, and (3) resource availability, and resource needs. This paper describes the techniques of resource manager (RM) handling above problems to support QoS of dynamic real-time applications on Grid. The contributions of this paper to solve problems are as follows: unification of dynamic resource requirements among heterogeneous hosts, control of resources in heterogeneous environments, and dynamic load balancing/sharing. Our heuristic allocation scheme works not only 257% better than random, 142% better than round robin, and 36.4% better than least load in QoS sensitivity, but also 38.6% better than random, 28.5% better than round robin, and 31.6% better than least load in QoS.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.305-312
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• 2014

This paper discusses real-time peak shaving algorithms for a large-scale battery energy storage system (BESS). Although several transmission and distribution functions could be implemented for diverse purposes in BESS applications, this paper focuses on a real-time peak shaving algorithm for an energy time shift, considering wind power generation. In a high wind penetration environment, the effective load levels obtained by subtracting the wind generation from the load time series at each long-term cycle time unit are needed for efficient peak shaving. However, errors can exist in the forecast load and wind generation levels, and the real-time peak shaving operation might require a method for wind generation that includes comparatively large forecasting errors. To effectively deal with the errors of wind generation forecasting, this paper proposes a real-time peak shaving algorithm for threshold value-based peak shaving that considers fuzzy wind power generation.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.425-430
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• 2022

A pumped storage power station is an important means to solve the problem of peak load regulation and ensures the safety of power grid operation. The doubly fed variable-speed pumped storage (DFVSPS) system adopts a doubly fed induction machine (DFIM) to replace the synchronous machine used in traditional pumped storage. The stator of DFIM is connected to the power grid, and the three-phase excitation windings are symmetrically distributed on the rotor. Excitation current is supplied by the converter. The active and reactive power of the unit can be quickly adjusted by adjusting the amplitude, frequency, and phase of the rotor-side voltage or current through the converter. Compared with a conventional pumped storage hydropower station (C-PSH), DFVSPS power stations have various operating modes and frequent start-up and shutdown. This study introduces the structure and principle of the DFVSPS unit. Mathematical models of the unit, including a model of DFIM, a model of the pump-turbine, and a model of the converter and its control, are established. Fast power control strategies are proposed for the unit model. A 300 MW model of the DFVSPS unit is established in MATLAB/Simulink, and the response characteristics in generating mode are examined.