• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.131-132
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• 2015

본 논문에서는 국제 규정에서 요구되는 고전압에 대한 전기적 안전성 확보를 위한 설계 기준 및 배터리 관리 시스템의 절연 설계 방법에 대해서 살펴보았다. 아울러 고전압 안전성 상태를 감시하는 지락파괴 감시기능의 동작 해석에 대한 연구를 진행하였으며, 실험을 통하여 그에 대한 타당성을 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.175-181
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• 2016

In the conventional E-bike, a 42 V/10 A Li-ion battery drives a 24 V/10 A BLDC motor via a 6-switch PWM DC/AC inverter. The major problems of the conventional battery-fed motor drive systems are listed as follows. To charge the battery, an external battery charger (adapter) is required, which degrades the portability of E-bike users. In addition, given the high-frequency operation of the motor drive inverter, the switching losses are significant, which degrades the whole power efficiency. High-voltage batteries (42 V) require a complex battery management system (BMS), which degrades the reliability of the battery pack. In this paper, an embedded boost-converter battery charger for E-bikes is proposed. The variable output boost converter, which converts 16.8 V battery voltage to the required variable voltage of the inverter input, can use a low-voltage battery and thus improve the reliability of batteries. By varying the inverter input voltage via boost converter, a DC link voltage control method can be applied to reduce the switching frequency of the inverter, which improves the whole power efficiency. Given that the function of a flyback charger is integrated in the proposed boost converter, the portability of the E-bike user can be maximized by excluding an external adapter. The validity of the proposed circuit will be confirmed by operation mode analysis and simulation. Moreover, experimental results of integrative charger using Li-ion battery and 200 W motor test will be showed with a prototype sample as well.

• Journal of Information Technology Applications and Management
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• v.30 no.1
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• pp.1-9
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• 2023

Interest in the future of the battery market is growing as Tesla announces plans to increase production of electric vehicles and to produce batteries. Tesla announced an action plan to reduce battery prices by 56% through 'Battery Day', which included expansion of factories to internalize batteries and improvement of materials and production technology. In the trend of automobile electrification, the expansion of the battery market, which accounts for 40% of the cost of electric vehicles, is inevitable, and the size of the electric vehicle battery market in 2026 is expected to increase more than five times compared to 2016. With the development of materials and process technology, the energy density of electric vehicle batteries is increasing while the price is decreasing. Soon, electric vehicles and internal combustion locomotives are expected to compete on the same line. Recently, the mileage of electric vehicles is approaching that of an internal combustion locomotive due to the installation of high-capacity batteries. In the EV battery market, Korean, Chinese and Japanese companies are fiercely competing. Based on market share in the first half of 2020, LG Chem, CATL, and Panasonic are leading the EV battery supply, and the top 10 companies included 3 Korean companies, 5 Chinese companies, and 2 Japanese companies. All-solid, lithium-sulfur, sodium-ion, and lithium air batteries are being discussed as the next-generation batteries after lithium-ion, among which all-solid-state batteries are the most active. All-solid-state batteries can dramatically improve stability and charging speed by using a solid electrolyte, and are excellent in terms of technology readiness level (TRL) among various technology alternatives. In order to increase the competitiveness of the battery industry in the future, efforts to increase the productivity and economy of electric vehicle batteries are also required along with the development of next-generation battery technology.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.495-502
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• 2020

In this paper, a power management circuit was designed to drive the emergency lighting LED in the underground facility for public utilities using magnetic energy harvest. The magnetic energy harvest consists of a harvest elements and power management circuits. The proposed circuit was made of a rectifier, a battery charging circuit, and an LED driving circuit. In normal times, the battery is charged with the harvested power, and in the event of an emergency, the energy stored in the battery is used to drive the LED. As a result of the measurement, it took two minutes to charge the 47 mF capacitor. This is the amount of power that can drive an LED for emergency lighting for about three and a half minutes. Through this, it was confirmed that the power management circuit for magnetic energy harvest proposed in this paper can be used as an emergency lighting LED-driven power device in an underground facility for public utilities where it is difficult to draw separate power.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.83-92
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• 2020

In this paper, we propose an efficient session management scheme for low-latency communications in 5G systems. The main idea of the proposed scheme is to prevent unnecessary reattempt signalling overhead when the session establishment for low-latency communications fails. Also, this method avoids network resource waste and battery drain of mobile devices. If a UE(User Equipment) fails to establish an Always-on PDU session for low-latency communications with the 5G systems because of network failure or resource unavailability, the proposed method prevents the UE's re-establishment of the Always-on PDU session by the specific information in the NAS(Non-Stratum) message from the 5G systems. Through simulation, we show that the proposed efficient session management scheme (ESMS) minimizes unnecessary signalling overhead and improves battery efficiency of mobile devices compared to existing legacy mechanism in 5G systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.1
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• pp.170-176
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• 2009

The efficiently power management is an important requirement traditionally in the mobile communication system which uses battery as their power source. Especially, it has been emphasized in the most devices, which has to provide high performance and various functions with an extended operating time. In this article, the adaptive power management technique for the core CPU unit in Embedded systems used widely for the mobile system thanks to its advantage on power consumption and physical size, is proposed.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1119-1120
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• 2008

The efficiently power management is an important requirement traditionally in the mobile communication system which uses battery as their power source. Especially, it has been emphasized in the most recent devices, which has to provide high performance and various functions with an extended operating time. In this article, the adaptive power management technique for the core processor unit in embedded systems used widely for the mobile system thanks to its advantage on power consumption and physical size, is proposed.

• Journal of Aerospace System Engineering
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• v.8 no.4
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• pp.7-17
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• 2014

Objective of this paper is to introduce a new technology known as prognostics and health management (PHM) which enables a real-time life prediction for safety critical systems under extreme loading conditions. In the PHM, Bayesian framework is employed to account for uncertainties and probabilities arising in the overall process including condition monitoring, fault severity estimation and failure predictions. Three applications - aircraft fuselage crack, gearbox spall and battery capacity degradation are taken to illustrate the approach, in which the life is predicted and validated by end-of-life results. The PHM technology may allow new maintenance strategy that achieves higher degree of safety while reducing the cost in effective manner.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.1
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• pp.1-7
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• 2006

In this paper, a novel power management structure for an energy harvesting pervasive system is proposed. The system considers the power state of each subsystem to assign proper power sources. The switch matrix structure utilizes each power source to reduce the peak current of the battery. The power management structure can be interfaced to an embedded system power supply without significant design change.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.1
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• pp.130-136
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• 2009

A lumped parameter model of Li-ion battery in hybrid electric vehicle(HEV) is constructed and system parameters are identified by using recursive least square estimation for different C-rates, SOCs and temperatures. The system characteristics of pole and zero in frequency domain are analyzed with the parameters obtained from different conditions. The parameterized model of Li-ion battery indicates highly dependant of temperatures. The system pole and internal resistance changes 6.6 and 18 times at $-20^{\circ}C$, comparing with those at $25^{\circ}C$, respectively. These results will be utilized on constructing model-based state observer or an on-line identification and an adaptation of the model parameters in battery management systems for hybrid electric vehicle applications.