• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.393-401
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• 2006

Energy consumption is an important design parameter for battery-operated embedded systems. Dynamic power management is one of the most well-known low-power design techniques. This paper proposes an online realtime scheduling algorithm, which we call energy-aware realtime scheduling using slack stealing (EARSS). The proposed algorithm gives the highest priority to the task with the largest degree of device overlap when the slack time exists. Scheduling result enables an efficient power management by reducing the number of state transitions. Experimental results show that the proposed algorithm can save the energy by 23% on average compared to the DPM-enabled system scheduled by the EDF algorithm.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.3
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• pp.151-156
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• 2015

Recently, an embedded flash memory has been widely used for the Internet of Things(IoT). Due to its nonvolatility, economical feasibility, stability, low power usage, and fast speed. With respect to power consumption, the embedded memory system must consider the most significant design factor. The objective of this research is to design high performance and low power NAND flash memory architecture including a dual buffer as a replacement for NOR flash. Simulation shows that the proposed NAND flash system can achieve better performance than a conventional NOR flash memory. Furthermore, the average memory access time of the proposed system is better that of other buffer systems with three times more space. The use of a small buffer results in a significant reduction in power consumption.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.2
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• pp.102-107
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• 2005

This paper presents the comparison and performance analysis for CPL and CMOS based designs. We have developed the Verilog-HDL codes for the proposed designs and simulated them using ModelSim for verifying the logical correctness and the timing properties of the proposed designs. The proposed designs are then analyzed at the layout level using LASI. The layouts of the proposed designs are simulated in Winspice for timing and power characteristics. The result shows that the new circuits presented consistently consume less power than the conventional design of the same circuits. It can also be seen that these circuits have the lesser propagation delay and thus higher speed than the conventional designs.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.88-90
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• 2009

Extremely-Low-Frequency(ELF) magnetic fields are generated around power cables and bus bars in power systems. Such the stray fields may cause disturbances to nearby electronic apparatus and affect even human health. In order to seeking out a proper way to reducing the fields, the first thing to do is to accurately predict field distribution around analysis models of interest. Then, optimization techniques should be applied for finding a more improved design than the initial one. To achieve this goal, commercial electromagnetic software, MagNet, is combined with evolution strategy algorithm. For verification of the proposed method, three-phase power line cables and busbar systems have been tested.

• Journal of the Korean Society of Systems Engineering
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• v.4 no.2
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• pp.45-54
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• 2008

This paper describes an operational concept of the network based future airborne force power using a systems engineering approach. The battlefield is changing to new system of systems that command and control by the network based BM/C4ISR. Also, it is composed of various sensors and shooters in an single theater. Future threats may be characterized as unmanned moving bodies that the strategic effect is great such as UAVs, cruise missile and tactical ballistic missiles. New threats such as low altitude stealth cruise missile may also appear. The implementation of future airborne force power network systems against these future threats is required to complex and integrated approach based on systems engineering. This work developed the operational concepts of the future airborne network system, and then derived the requirements for performing missions effectively. In addition, the scheme of future airborne force power network systems is presented.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.301-304
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• 2001

The analog multiplier is very useful building block in many circuits such as filter, frequency-shifter, and modulators. In recent year, The main design issue of circuit designer is low-voltage/low-power system design, because of all systems are recommended very integrated system and portable system In this paper, the proposed the four-quadrant analog multiplier is using the bulk-driven techniques. The bulk-driven technique is very useful technique in low-voltage system, compare with gate-driven technique. therefore the proposed analog multiplier is operated in 1V supply voltage. And the proposed analog multiplier is low power dissipation compare with the others. therefor the proposed analog multiplier is convenient in low-voltage/low-power in system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.343-346
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• 2009

The grounding system of low voltage power systems is TT grounding system in Korea. In order to follow the international standard, TN grounding system is adopted. However, the performance of grounding systems has not been evaluated. This paper deals with the experimental results of protection ability of grounding system when lightning surge invades to the neutral line of low voltage power system. As a result, the TT grounding system is most frail for the lightning surge and it does not protect the electrical devices. On the other hand, the TN grounding system perfectly protects the electrical equipment and prevents the electric shock for human through the equipotential bonding. In case of TN system with supplement grounding, it is very important to lower the supplement grounding resistance to protect the electrical equipment and electric shock for human.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.1
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• pp.9-14
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• 2008

Since they use the low switching frequency in multilevel inverter systems, they generate the high low frequency harmonic components. Generally, LC filter is used at the output terminal of inverter systems to solve this problem. But it causes a voltage drop at the output terminal by use of damping resistors, and causes the problem in which system efficiency decreases due to power loss of the damping resistor. In this paper, we proposed an output filter design method for NPC three-level inverter systems with low switching frequency. And we analyzed the efficiency of the proposed filter system, and the effectiveness of the proposed system is verified by simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1159-1160
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• 2006

As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, this has raised potential problems of network protection on electrical power system. One of the numerous problems is an Island phenomenon. There has been an argument that because the probability of islanding is extremely low it may be a non-issue in practice. However, there are three counter-arguments: First, the low probability of islanding is based on the assumption of 100% power matching between the PVPCS and the islanded local loads. In fact, an island can be easily formed even without 100% power matching (the power mismatch could be up to 30% if only traditional protections are used, e.g. under/over voltage/frequency). The 30% power-mismatch condition will drastically increase the islanding probability. Second, even with a larger power mismatch, the time for voltage or frequency to deviate sufficient to cause a trip, plus the time required to execute the trip (particularly if conventional switchgear is required to operate), can easily be greater than the typical re-close time on the distribution circuit. And, third, the low-probability argument is based on the study of PVPCS. Especially, if the output power of PVPCS equals to power consumption of local loads, it is very difficult for the PVPCS to sustain the voltage and frequency in an island. Unintentional islanding of PVPCS may result in power-quality issues, interference to grid-protection devices, equipment damage, and even personnel safety hazards. So the verification of anti-islanding performance is strongly needed. In this paper, the authors propose the improved RPV method through considering power quality and anti-islanding capacity of grid-connected three-phase PVPCS in IEEE Std 1547 ("Standard for Interconnecting Distributed Resources to Electric Power Systems"). And the simulation and experimental results are verified.

• New & Renewable Energy
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• v.18 no.3
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• pp.32-42
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• 2022

Rapid spread of intermittent renewable energy has amplified the instability and uncertainty of power systems. The Korea Power Exchange (KPX) promoted efficient management by opening the power brokerage market in 2019. By combining small-scale intermittent renewable energy with a flexible facility through the power brokerage market, the KPX aims to develop a virtual power plant system that will allow the conversion of existing intermittent renewable energy into collective power plants. However, the participation rate of renewable power owners in the power brokerage market is relatively low because other markets such as the small solar power contract market or the Korea Electric Power Corporation power purchase agreement are more profitable. In this study, we used a choice experiment to determine the attributes affecting the participation rate in the power brokerage market for 113 renewable power owners and estimate the value of the power brokerage market. According to the estimation results, a low smart meter installation cost, low profit variations, long contract periods, and few clearances increased the probability of participation. Moreover, the average value of the power brokerage market was estimated to be 2.63 million KRW per power owner.