• Journal of Power Electronics
• /
• v.6 no.1
• /
• pp.18-28
• /
• 2006

The Electric Power Subsystem (EPS) is one of the most critical systems on any satellite because nearly every subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to withstand radiation, thermal cycling and vacuums in hostile space environments, as well as subsystem degradation over time. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit. After satellite separation from the launch vehicle (LV) to its orbit, in almost all situations, the satellite subsystems (attitude determination and control, communication and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) besides the consumed power in the EPS management device. At this point (separation point, detumbling mode), the satellite's angular motion is high and the orientation of the solar arrays, with respect to the Sun, will change in a non-uniform way, so the amount of power generated by the solar arrays will be affected. The objective of this research is to select satellite EPS component types, to estimate solar array illumination parameters and to determine the efficiency of solar arrays during both detumbling and normal operation modes.

• Journal of Korea Multimedia Society
• /
• v.15 no.12
• /
• pp.1456-1463
• /
• 2012

In this paper, we study the ON/OFF control policy of base stations in two-tier heterogeneous cellular networks to minimize the total power consumption of the system. Using heterogeneous cellular networks is a potential approach of providing higher throughput and coverage compared to conventional networks with only macrocell deployment, but in fact heterogeneous cellular networks often operates regardless of total power consumption, which is a very important issue of modern cellular networks. We propose a policy that controls the activation/deactivation of base stations in heterogeneous cellular networks to minimize total power consumption. Under this policy, the total power consumed can be significantly reduced when the traffic is low while the QoS requirement is satisfied.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.5
• /
• pp.267-270
• /
• 2014

This paper presents the comparative performance of an adaptive FIR filter for a Delayed LMS algorithm. The delayed error signal was used to obtain a Delayed LMS algorithm to allow efficient pipelining for achieving a small critical path and area efficient implementation. This paper presents hardware efficient results (device utilization parameters) and power consumed. The FPGA families (Artix-7, Virtex-7, and Kintex-7) for a low voltage perspective are shown. The synthesis results showed that the artix-7 CMOS family achieves the lowest power consumption of 1.118 mW with 83.18 % device utilization. Different Precision strategies, such as the speed optimization and power optimization, were imposed to achieve these results. The algorithm was implemented using MATLAB (2013b) and synthesized on the Leonardo spectrum.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.7A
• /
• pp.451-466
• /
• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• Proceedings of the KIEE Conference
• /
• 1999.07f
• /
• pp.2626-2627
• /
• 1999

The device we have developed is the automatic shut off equipment which will reduce energy consumption when an equipment is in stand by power state. The principle for this system is when a man is moving, electricity will flow by setting a on-off light system. At night, in the stand-by power state the electric supply will be shut off immediately which will reduce energy consumption. Energy consumed by 24hour operating machines and stand-by electronic devices will be reduced by pulse signals which will give power supply when needed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.10
• /
• pp.630-634
• /
• 2016

In this paper, we analyzed the power consumption and the accumulated energy in HTSC (high-TC superconducting elements) according to the resistance of HTSC element and the winding current of transformer type SFCL (superconducting fault current limiter) using double quench. For the analysis, two different inductances of the one secondary winding among two secondary windings comprising the transformer type SFCL were selected and the short-circuit tests were carried out. The consumed power and the accumulated energy in HTSC element connected into the secondary winding with larger inductance were analyzed to be larger compared to the one connected into the secondary winding with lower inductance.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.286-293
• /
• 2008

DC transit system has been adopted in the metropolitan area, Korea since 1974. EMU in this system always reiterates that acceleration and retardation. When EMU decelerates using electric breaking, regenerative power occurs. Regenerative power can be consumed in vicinity EMC on the same line or in resistor. If DC transit system has inverter for reusing regenerative power, Energy efficiency in DC transit system will be increased. This paper present the developed inverter for regenerative power and its field test. Test result of developed inverter is presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.5
• /
• pp.83-89
• /
• 2004

The importance of the Load Power Factor(LPF) management is newly noticed from the voltage management and operation of the power system due to the rapidly increasing reactive power consumed. Therefore, this paper proposes the regional, seasonal and hourly Representative Model of Load Power Factor(RMLPF) considering load characteristics of all 154/22.9[kV] substations. The RMLPF is used to present a precision improvement of power system analysis and security. Computation of representative model of load utilizes the average flow method based on moving average method. The Energy Management System(EMS) data are used as the source to assess the load power factor.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1885-1886
• /
• 2006

The thermal energy from nuclear fission is transferred to the steam generator which is a kind of a large heat exchanger. After the feedwater is injected into the steam generator and absorbs the thermal energy, it is converted into the steam. This steam goes into the turbine. The balance between the generated energy and the consumed energy is required for the nuclear power plant to be stable. For the purpose of which, the feed water, a parameter for energy transfer, should be controlled in stability. Usually, the nuclear power plants are operated in base load in the view of power system for the stability of fission system. Therefore, though there will be almost no unbalance, there can be some instability from unbalance in case of startup/shutdown or disturbance. In this case, the controllability of feedwater pump is very important for the quick recover of stability.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.1
• /
• pp.54-60
• /
• 2010

This paper presents a new algorithm for determining generator operation point for maintaining stability considering generator faults in Jeju-Haenam HVDC system. As the HVDC system consumes reactive power for the transmission of active power substantially, compensation of reactive power is essential. And the HVDC system is operated on frequency control mode. That is to say, the HVDC system almost manages system frequency. Therefore, we recognized that the Jeju system could be unstable if the reactive power consumed by the HVDC is insufficient when out-of-step occurs with large generators. When the solution of power flow analysis does not converge due to the unstable system phenomenon, we have difficulty in establishing countermeasures as the post-fault information is not available. In this paper, for the purpose of overcoming this difficulty in establishing countermeasures, we introduce the CPF(Continuation Power Flow) algorithm. This paper suggests an algorithm for calculating the output limitation of the generator to maintain the stability in case of generator fault in the Jeju system.