• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.194-201
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• 2007

As the performance of the mobile terminal becomes higher, the power consumption gradually increases. As a result, power management is one of the most important issues in mobile system with battery. In this paper, we describe an DPM(Dynamic Power Management) using DVS(Dynamic Power Management) as a power management mechanism in Qplus operating system. DVS generally considers a specific device such as CPU, whereas we consider the relations with other hardware components as well as each component. We specially focus on the relation between CPU, memory and LCD devices. We also designs a kernel monitor to collect information to decide the policy for power management. According to the experimental results, the proposed method enables to save much power.

• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.42-54
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• 2008

In recent years, embedded systems have been expanding their application domains from traditional embedded systems such as military weapons, robots, satellites and digital convergence systems such as celluar phones, PMP(Portable Multimedia Player), PDAs(Personal Digital Assistants) to Next Generation Personal Computers(NGPCs) such as eating PCs, wearable computers. The NGPCs are network-based, human-centric digital information devices diverged from the traditional PCs used mainly for document writing, internet searching and database management. Wearable computers with battery capacity and memory size limitations have to use real-time operating systems with small footprints and low power management techniques to provide user's QoS in spite of hardware constraints. In this paper, we have designed and implemented a low-power RTOS (called eRTOS) for wearable computers. The implemented eRTOS has 18KB footprints and the dynamic power management and the device power management schemes are adapted in it. Experimental results with wearable computer applications show that the low power techniques could save energy up to 47 %.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.292-295
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• 2001

This paper describes the implementation of UPS system controlled by the DSP. The digital techniques have been used tn overcome the problems of UPS system controlled by analog control circuits. By developing these systems using the digital technique we could increase the reliability and improve the electrical characteristics. And we designed and developed the system which is able to control UPSs and to monitor errors, statuses and actual values transmitted from UPS through internet. The UPSs also impose high demands on battery life time, reliability and energy-efficiency. These requirements can only be met by employing sophisticated battery management system(BMS). Therefore, a highly accurate, universal and inexpensive measuring system for BMS was developed.

• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.1-7
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• 2004

In this paper, the new improved method for photovoltaic system was studied available for a lighting load by measuring the state of charge of lead-acid batteries. Photovoltaic systems has been evaluated as one of the most new and renewable energy and especially, the Stand-Alone Photovoltaic system has been used to a street light, a road sign light, an air caution light, an emergency call. Many Stand-Alone PV system are installed by a group. Although the pre-installation cost of PV system is high and it has not been operated due to the absence of optimal management standards. In this paper, it is proposed a new operating method by the measurement of lead-acid battery's SOC with a Ah balancing.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.131-138
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• 2017

QR/NFC tags have been utilized in various fields like exhibition, museum, and so on, but they have a drawback that they are read-only fundamentally. We devise a novel device called a smart memory tag (below mem-tag) which is supplemented with the write function through combining a flash memory into a NFC tag. A mem-tag is composed of an NFC tag, an MCU, a flash memory, a bluetooth module, and a battery, and is inter-operating with smartphones via bluetooth communication. It can be used in a bulletin board to support writing replies and in a check-in service to verify the presence of the site. What matters is that users' inter-operations are borne to be asynchronous, which leads to the energy consumption to wait for users' actions. Sleep mechanisms and asynchronous MAC protocols used in ubiquotous sensor networks cannot avoid the consumption of battery. In this paper, we propose a touch and play scheme for minimizing the consumption of battery that the MCU wakes up and PLAY when a user TOUCH the mem-tag. We implemented the system to show that our scheme lets the mem-tag work 50 times longer than the sleep and wake-up scheme.

• Smart Structures and Systems
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• v.29 no.5
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• pp.661-675
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• 2022

In this paper, an electric vehicle drives with efficient control and low cost hardware using four quadrant DC converter with Permanent Magnet Direct Current (PMDC) motor fed by DC boost converter is presented. The main idea of this work is to improve the energy efficiency of the conversion chain of an electric vehicle by inserting a boost converter between the battery and the four quadrant-DC motor chopper assembly. Consequently, this method makes it possible to maintain the amplification gain of the 4 quadrant chopper constant regardless of the battery voltage drop and even in the presence of a fault in the battery. One of the most important control problems is control under heavy uncertainty conditions. The higher order sliding mode control technique is introduced for the adjustment of DC bus voltage and mechanical motor speed. To implement the proposed approach in the automotive field, experimental tests were carried out. The performances obtained show the usefulness of this system for a better energy management of an electric vehicle and an ideal control under different operating conditions and constraints, mostly at nominal operation, in the presence of a load torque, when reversing the direction of rotation of the motor speed and even in case of battery chamber failure. The whole system has been tested experimentally and its performance has been analyzed.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.111-115
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• 2012

In this paper, a solar energy powered bicycle linked to a wireless sensor network (WSN) which monitors the transfer of solar energy to an electrical energy storage unit and an analysis of its effectiveness is proposed. In order to achieve this goal, a solar-powered bicycle with an attached ZigBee and a far-end wireless network supervisory system is setup. Experimental results prove that our prototype, solar energy powered bicycle, can achieve enough solar energy for charging a two lead-acid battery pack. As a result, the user, through use of a wireless network in the parking period can be kept aware of the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information of the bicycle through an internet interface.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.72-82
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• 2023

Effective thermal management in a battery electric vehicle (BEV) is crucial for reducing energy consumption and maximizing driving range in cold climates. Consequently, original equipment manufacturers are actively investing in the development of local heating systems. Visualizing occupant thermal behaviors or comfort can readily provide valuable insights that would substantially impact the design and control strategies of such microclimate systems. This study uses MATLAB for three-dimensional visualization of human thermal psychology. The developed program enables qualitative assessment of occupant comfort in BEVs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.317-324
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• 2007

Most conventional hybrid systems using renewable energy sources have been applied for stand-alone operation, but Utility-interface may be an useful and viable option for hybrid systems. Grid-connected operation may have benefits such as reduced losses in power system distribution, utility support in demand side management, and peak load shaving. This paper addresses power control and dynamic performance of a grid-connected PV/wind/BESS hybrid system. At all times the PV way and the wind turbine are individually controlled to generate the maximum energy from given weather conditions. The battery energy storage system (BESS) charges or discharges the battery depending on energy gap between grid invertger generation and production from the PV and wind system. The BESS should be also controlled without too frequently repeated shifts in operation mode, charging or discharging. The grid inverter regulates the generated power injection into the grid. Different control schemes of the grid inverter are presented for different operation modes, which include normal operation, power dispatching, and power smoothing. Simulation results demonstrate that the effectiveness of the proposed power control schemes for the grid-interactive hybrid system.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.364-371
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• 2005

Fuel cell systems(FCS) have a financial and environmental advantage by providing electricity at a high efficiency and useful heat. For use in a residence, a polymer electrolyte fuel cell system(PEFCS) with a battery pack and a hot water storage tank has been modelled and simulated. The system is operated without connection to grid line. Its electric conversion efficiency and heat recovery performance are highly dependent on operation strategies and also on the seasonal thermal and electric load pattern. The output of the fuel cell is controlled stepwise as a function of the state of the battery and/or the storage water tank. In this study various operation strategies for cogeneration fuel cell systems are investigated. Average fuel saving rates at different seasons are calculated to find proper load management strategy. The scheme can be used to determine the optimal operating strategies of PEFCS for residential and building applications.