• Resources Recycling
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• v.31 no.4
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• pp.3-11
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• 2022

Owing to the increasing demand for electric vehicles (EVs), appropriate management of their waste batteries is required urgently for scrapped vehicles or for addressing battery aging. With respect to technological developments, data-driven diagnosis of waste EV batteries and management technologies have drawn increasing attention. Moreover, robot-based automatic dismantling technologies, which are seemingly interesting, require industrial verifications and linkages with future battery-related database systems. Among these, it is critical to develop and disseminate various advanced battery diagnosis and assessment techniques to improve the efficiency and safety/environment of the recirculation of waste batteries. Incorporation of lithium-related chemical substances in the public pollutant release and transfer register (PRTR) database as well as in-depth risk assessment of gas emissions in waste EV battery combustion and their relevant fire safety are some of the necessary steps. Further research and development thus are needed for optimizing the lifecycle management of waste batteries from various aspects related to data-based diagnosis/classification/disassembly processes as well as reuse/recycling and final disposal. The idea here is that the data should contribute to clean design and manufacturing to reduce the environmental burden and facilitate reuse/recycling in future production of EV batteries. Such optimization should also consider the future technological and market trends.

• Journal of the military operations research society of Korea
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• v.2 no.1
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• pp.163-176
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• 1976

The artillery fire is characterized by great damage that can be inflicted simultaneously to an area through concentrated firing. The field artillery guns used in R.O.K. Army are generally old. Thus high values of their velocity errors cause wide dispersion of shell landings. Therefore effects of the concentrated firing is lessened. In this paper a general model which considers all error factors involved in firing in general, is established first. Then from this a basic model which includes the errors involved in concentrated firing only, such as the ballistic error, velocity error, target density function, and damage function, is extracted. Among many weapon systems now in use a specific one called gun 'A' is selected and its concentration effects are measured through computer simulation. The results show that as the velocity error of a battery increases, its target coverage capability, i. e. concentration effect, decreases. Therefore the need arises for the field artillery commander to know beforehand characteristics, i.e. velocity errors, of the guns in his unit and also to carefully examine the problem of battery arrangement with the gun characteristics in mind in order to maximize the damage effects of his artillery unit.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.119-122
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• 2020

With recent ESS (Energy Storage System) fire accident, the fault protection performance is becoming more important. However, there has never been any experiments with the protection performance on the faults in the ESS system level. In this study, the effect of AC ground fault and IGBT (Insulated Gate Bipolar mode Transistor) short-circuit failure on MW class ESS was performed experimentally for the first time in the world. First of all, the effect of the AC single line ground fault on battery was analyzed. Moreover, the transient voltage was investigated as a function of the battery capacity and the power level. Finally, the breaking capability and insulation performance of ESS were examined under PCS short-circuit fault condition. Through the tests, it was found that ESS protection system safely blocked the faulty current regardless of the faults, whereas the electronic parts such as IGBT and MC (Magnetic Contactor) were broken by the fault current. Also, the electrical breakdown in ESS resulted from the transient voltage during the protection process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.587-593
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• 2021

Since 2017, a total of 29 fire accidents have occurred in energy storage systems (ESSs) as of June 2020. The common mode voltage (CMV) is one of the electrical hazards that is assumed to be a cause of those fire accidents. Several cases of CMV that violate the allowable insulation level of a battery section are being reported in actual ESS operation sites with △-Y winding connections. Thus, this paper evaluates the characteristics of CMV. An ESS site was modeled with an AC grid, PCS, and battery sections using PSCAD/EMTDC software. As a result of a simulation based on the proposed model, it was confirmed that characteristics of CMV vary significantly and are similar to actual measurements, depending on the grounding method of the internal transformer for PCS. The insulation level of the battery section may be severely degraded as the value of CMV exceeds the rated voltage in case of a grounding connection. It was found that the value of CMV dramatically declines when the internal transformer for PCS is operated as non-grounding connection, so it meets the standard insulation level.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.91-97
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• 2020

Lithium-ion batteries (LIBs) have a longer lifespan, higher energy density, and lower self-discharge rates than other batteries, therefore, they are preferred as an Energy Storage System (ESS). However, during years 2017-2019, 28 ESS fire accidents occurred in Korea, and accurate capacity estimation of LIB is essential to ensure safety and reliability during operations. In this study, data-driven modeling that predicts capacity changes according to the charging cycle of LIB was conducted, and developed models were compared their performance for the selection of the optimal machine learning model, which includes the Decision Tree, Ensemble Learning Method, Support Vector Regression, and Gaussian Process Regression (GPR). For model training, lithium battery test data provided by NASA was used, and GPR showed the best prediction performance. Based on this study, we will develop an enhanced LIB capacity prediction and remaining useful life estimation model through additional data training, and improve the performance of anomaly detection and monitoring during operations, enabling safe and stable ESS operations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1555-1570
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• 2016

For monitoring forest fires, a real-time system to prevent fires in wider areas should be supported consistently. However, there has still been a lack of the support for real-time system related to forest fire monitoring. In addition, the 'real-time' processing in a forest fire detection system can lead to excessive consumption of energy. To solve these problems, the intelligent data acquisition of sensing nodes is required, and the maximum energy savings as well as rapid and accurate detection by flame sensors need to be done. In this regard, this paper proposes a node built-in filter algorithm for intelligent data collection of sensing nodes for the rapid detection of forest fires with focus on reducing the power consumption of the remote sensing nodes and providing efficient wireless sensor network-based forest environment monitoring in terms of data transmission, network stability and data acquisition. The experimental result showed that battery life can be extended through the intelligent sampling of remote sensing nodes, and the average accuracy of the measurement of flame detection based on the distance is 44%.

• Fire Science and Engineering
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• v.24 no.6
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• pp.61-68
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• 2010

In this paper, a research and development result for the implementation of single station fixed temperature detector for residential fire prevention is described. The detector was developed for the certification in Japanese market because of very low domestic market situation. It is in the situation that there is no other regulation especially for residential detectors in Korea, Japanese case has been reviewed. Investigation of domestic legal circumstances and a comparative study for the test standard owned by KFI (Korea Institute of Fire Industry & Technology) and JFEII (Japan Fire Equipment Inspection Institute) respectively are also indicated. The detector alarms with a buzzer and an indicating LED. In the implementation ultra low power MCU(Micro Controller Unit) is applied to control the sleeping state and the monitoring state properly with low current consumption. To sense the temperature fast response thermistor is adopted in the design of fixed temperature residential detector. Automatic test function and alarm stop function are also considered in the design. The major factors which influence to current consumption are explained for the purpose of design reference. Main electronics circuit parts related to it's characteristics of the detector are described. It is explained that the measured current and experimental result of the battery discharge can be met over 10 years operation.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.50-55
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• 2023

Lithium-ion secondary batteries are currently in high demand and supply. The purpose of this study is to secure the safety of the process by studying the combustion characteristics of EC(Ethylene Carbonate), Which is mainly used as an electrolyte organic solvent for lithium ion batteries. The flash points of the EC by using Setaflash and Pensky-Martens closed-cup testers were experimented at 141 ℃ and 143 ℃, respectively. The flash points of the EC by Tag and Cleveland open cup testers were experimented at 152 ℃ and 156 ℃, respectively. The AIT(Auto Ignition Temperature) of the EC was experimented at 420 ℃. The LEL(Lower Explosive Limit) calculated by using lower flash point of Setaflash was calculated at 3.6 Vol.%.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.4
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• pp.117-122
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• 2021

In recent years, human damage and loss of money due to various disasters such as typhoons, earthquakes, forest fires, landslides, and wars are steadily occurring, and a lot of manpower and funds are required to prevent and recover them. In this paper, we designed and developed a disaster drone system based on artificial intelligence in order to monitor these various disaster situations in advance and to quickly recognize and respond to disaster occurrence. In this study, multiple disaster drones are used in areas where it is difficult for humans to monitor, and each drone performs an efficient search with an optimal path by applying a deep learning-based optimal path algorithm. In addition, in order to solve the problem of insufficient battery capacity, which is a fundamental problem of drones, the optimal route of each drone is determined using Ant Colony Optimization (ACO) technology. In order to implement the proposed system, it was applied to a forest fire situation among various disaster situations, and a forest fire map was created based on the transmitted data, and a forest fire map was visually shown to the fire fighters dispatched by a drone equipped with a beam projector. In the proposed system, multiple drones can detect a disaster situation in a short time by simultaneously performing optimal path search and object recognition. Based on this research, it can be used to build disaster drone infrastructure, search for victims (sea, mountain, jungle), self-extinguishing fire using drones, and security drones.

• Journal of IKEEE
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• v.23 no.4
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• pp.1280-1287
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• 2019

Grid-connected bidirectional PCS(Power Conditioning System) technology is a technology for implementing distributed renewable energy smart grid. And it is always charged by using power collected from solar modules and commercial grid power among vast smart grid systems, and stored when needed.It is a hybrid energy storage device that allows power to be released into the low voltage system. To this end, a PV input power converter with MPPT function, a bidirectional power converter for battery charging and discharging, and a DC Link input are output to a 3 phase 380V AC system, and if nessary, the bidirectional DC/DC converter We designed and developed a PCS with three power converter structures composed of inverters that perform battery charging. Currently, this system is applied to the site of Jeju, which is vulnerable to power outages and fire accidents.