• Journal of the Korean Solar Energy Society
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• v.40 no.3
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• pp.21-31
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• 2020

The government mandates gradually zero energy building and Photovoltaic power generation systems installed in buildings are emerging as the most realistic alternative to increase the independence rate of building energy. In this study, we propose a method to reduce the power consumption of households by increasing the PV capacity of balconies and applying the method used the charged electric power stored in batteries after sunset. In order to evaluate the electric power energy savings of the residential BESS, a balcony PV 1.2 kW and a battery pack 2 kWh were installed for 9 houses in 4 apartments in Seoul and Gyeonggi-do. The BESS is charged when the balcony PV is generated electric power, and when solar power generation is finished, it supplies power to the electric appliances connected to the load. As a result of installing the solar PV module 1.2 kW and 2 kWh class BESS for 3 households located in Seoul and Gyeonggi-do, the average electric power consumption saving rate was 40%. The reduction in electricity consumption in the case of zero generation surplus power by maximizing the utilization rate of BESS has been improved to about 53%. Therefore, in order to increase the self-sufficiency rate of electric energy in apartment houses, it is effective to increase the solar photovoltaic capacity of the balcony and apply the residential BESS. In the future, it is believed that the balcony PV and home BESS will play a key role in achieving mandatory zero-energy housing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.403-408
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• 2016

Lithium-ion batteries are commonly employed in hybrid electric vehicles (HEVs), and achieving high energy density in the battery has been one of the most critical issues in the automotive industry. Because liquid cooling containing antifreeze is important in automotive batteries to enable cold starts, an effective geometric configuration for high-cooling performance should be carefully investigated. Battery cooling with antifreeze has also been considered to realize successful cold starts. In this article, we theoretically investigate a specific property of an antifreeze cooling battery system, and we perform numerical modeling to satisfy the required thermal specifications. Because a typical battery system in HEVs consists of multiple stacked battery cells, the cooling performance is determined mainly by the special properties of antifreeze in the coolant passage, which dissipates heat generated from the battery cells. We propose that the required cooling performance can be realized by performing numerical simulations of different geometric configurations for battery cooling. Furthermore, we perform a theoretical analysis as a design guideline to optimize the cooling performance with minimum power consumption by the cooling pump.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.43-49
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• 2021

This research shows how is designed, and its performance is evaluated on the ground for the VTOL drone before the flight test initiates. The targeted drone weight is approximately 45 kg including battery packs, and 4 motors are utilized to produce thrust and control directions. 30 min flight schedules were simulated to estimate the total power consumptions which result in 2.4 kWh. Then, two packs of 13-cells lithium-polymer battery with operating voltage ranging between 54 V and 44 V with up to 4 C-rate were fabricated to safely operate a VTOL drone. Moreover, the battery management system was installed to prevent over and under-voltage and over-current while running a battery system. To finally verify battery's performance, we conducted a ground evaluation for discharging battery tests at -10 ℃, 25 ℃ and 40 ℃, resulting in satisfying simulated power consumption conditions for flight schedules.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1196-1199
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• 2017

A series-hybrid power system was designed for quad-tilt prop UAV and the characteristics was analysed. The power system consists of a 4.5kW rotary engine-generator and a li-battery as power sources, a power controller manages the overall power and supplies to the vehicle system. The output power of the engine is to be matched with the generator performance considering mechanical driving loss and generating efficiency, and also loss for charging and discharging of the battery energy. It is applied that the constant speed operation of the engine-generator to minimize overall fuel consumption by integrating the generating power and the battery energy, consequentially the battery capacity and characteristics could be important factors for improvement of the system efficiency.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.258-263
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• 2011

In this paper, a high quality battery charge-discharge controller for new & renewal energy power generation system is designed. The proposed new controller has a function to manipulate the battery charging current precisely and it is suitable for various batteries including Lead-Acid battery generally used for solar power generation system. LCD display function is implemented to enhanced the user's convenience and minimization of standby power consumption is realized by optimal design using CAD tools.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_1
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• pp.669-681
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• 2021

As the supply of xEV in Korea is rapidly increasing, the amount of waste batteries is expected to increase rapidly, but the current recycling system for waste xEV batteries is very insufficient. In order to properly utilize the xEV reusable battery module, it is essential to classify it into a type that has similar discharge characteristics to the current state of health(SOH), which is the discharge capacity of the battery. This paper proposes a system that can minimize the exchange of energy with the KEPCO system by using the charging/discharging method by circulating power between batteries in order to minimize the power consumption when charging and discharging waste batteries. In the proposed system, a function to measure parameters during the charging/discharging test of the waste battery was implemented to build a customized big date for the test waste battery. In addition, the dynamic characteristics of the proposed circuit were analyzed using PSIM, which is useful for power electronics analysis, and the validity of the proposed circuit was verified through experiments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.393-401
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• 2024

Recently, the Internet of Things (IoT) has been widely used in industries and daily life that directly affect human safety, life, and assets. However, IoT devices, which need to meet low-cost, lightweight, and low-power requirements, face a significant problem of shortened battery lifetime due to battery draining attacks and interference. To solve this problem, the 802.11ba standard for the Wake-up Receiver (WuR) has emerged, this feature is playing a crucial role in minimizing energy consumption. However, the WuR protocol did not consider security mechanisms in order to reduce latency and overhead. Therefore, in this study, anAdaptive Power Saving Mechanism (APSM) is proposed for low-power WuR to counter battery draining attacks. APSM can minimize abnormally occurring power consumption by exponentially increasing power-saving time in environments prone to attacks. According to experimental results, the proposed APSM improved energy consumption efficiency by a minimum of 13.77% compared to the traditional Legacy Power Saving Mechanism (LPSM) when attack traffic ratio is 10% or more of the total traffic.

• KIISE Transactions on Computing Practices
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• v.23 no.5
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• pp.328-333
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• 2017

Mobile game apps, which are popular in various mobile devices, tend to be power-hungry and rapidly drain the device's battery. Since a long battery lifetime is a key design requirement of mobile devices, reducing the power consumption of mobile game apps has become an important research topic. In this paper, we investigate the power consumption characteristics of popular mobile games with multiple threads, focusing on the inter-thread. From our power measurement study of popular mobile game apps, we observed that some of these apps have abnormally high-load threads that barely affect the user's gaming experience, despite the high energy consumption. In order to reduce the wasted power from these abnormal threads, we propose a novel technique that detects such abnormal threads during run time and reduces their power consumption without degrading user experience. Our experimental results on an Android smartphone show that the proposed technique can reduce the energy consumption of mobile game apps by up to 58% without any negative impact on the user's gaming experience.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1455-1463
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• 2017

Global economy has recorded low growth, low consumption, high unemployment rate, high risk, short boom and long recession. As a result, maritime economy declines and the reduction of maintenance costs is inevitable. Thus, Studies such as green ship, eco ship, and smart ship are being actively conducted to save energy of ship. Power management system that use batteries in green ship is an important research area. In this paper, we analyze the heavy load control of a power management system of a general ship using only a generator, and study a heavy load control algorithm for a battery connected power management system. To study this, a structure of battery connected power management system is proposed and a battery connected power simulator was constructed based on the proposed system. Through the simulator, the operation of the battery according to the heavy load control is defined and confirmed in the battery connected power management system.

• Journal of Information Technology Services
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• v.6 no.1
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• pp.141-149
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• 2007

Sensor node's mobility brings new challenges to data dissemination in large sensor networks. Frequent location updates of sensor nodes can lead to both excessive drain of sensor's limited battery supply and increased collisions in wireless transmissions. Conventional studies for routing protocols in wireless sensor networks are not enough to cover energy consumption and migration of sensor nodes. This study proposes a dynamic routing protocol based on the SPIN considering energy consumption and the migration, and also shows the effectiveness of the proposed routing protocol.