• 한국지열·수열에너지학회논문집
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• 제18권4호
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• pp.1-11
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• 2022

In this study, the thermal runaway of NCM and LFP batteries were compared and analyzed through numerical analysis under various conditions. Comparing the thermal runaway of the NCM622 (18650) battery cell and the LFP (18650) battery cell through oven test simulation, the LFP battery did not show thermal runaway, whereas the NCM622 battery temperature increased to 710℃ in 12 minutes. To observe the thermal runaway and propagation of the prismatic LFP battery cell, the internal temperature was set at 200℃ and the oven test simulation was conducted. It was found that thermal runaway occurred at 391℃ after 47 minutes. As a result of observing thermal runaway propagation by placing five NCM622 and LFP battery cells, the thermal runaway propagation was clearly observed in the case of the NCM622 battery, but in the case of the LFP battery, thermal runaway was not observed after the first cell. From the third battery cell, it was confirmed that the temperature change was very insignificant, and through this, it is considered that the LFP battery is relatively safe compared to the NCM battery in terms of the thermal runaway propagation of the battery.

• 문화기술의 융합
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• 제9권5호
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• pp.569-582
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• 2023

납축전지는 가장 오래된 충전식 배터리 시스템으로 현재까지 충전식 배터리 분야에서 자리를 지키고 있다. 이 배터리는 다양한 이유로 열폭주 현상이 생기는데 이는 큰 사고로 이어질 가능성이 있다. 그렇기 때문에 열폭주 현상을 예방하는 것은 배터리 관리 시스템의 핵심부분이다. 최근에는 열폭주 위험 배터리 셀을 기계학습으로분류하는 연구가 진행 중이다. 본 논문에서는 비지도학습인 DBSCAN 클러스터링과 통계적 방법을 사용하여 열폭주 위험 셀 탐지 및 검증 알고리즘을 제안하였다. BMS에서 측정한 lead-acid 배터리의 저항 값만을 사용하여 열폭주 위험 셀 분류 실험을 진행하였고 본 논문에서 제안한 알고리즘이 열폭주 위험 셀을 정확히 검출해 냄을 보여주었다. 또한 본 논문에서 제안한 알고리즘을 사용하여 배터리 내 열폭주 위험이 있는 셀과 노이즈가 심한 셀을 분류할 수 있었으며 그리드 서치를 통한 DBSCAN 파라미터 최적화를 통해 열폭주 위험 셀을 초기에 검출해 낼 수 있었다.

• 한국지열·수열에너지학회논문집
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• 제17권2호
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• pp.1-10
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• 2021

Lithium-ion batteries with high energy density, long cycle life and other advantages, have been widely used to energy storage systems(ESS). But as ESS fires frequently occur, the safety concern has become the main obstacle that hinders the large-scale applications of lithium-ion batteries. Especially, thermal runaway is the key scientific problem in battery safety research. Therefore, in this study, we performed a numerical analysis on the thermal runaway phenomenon of NCM111, NCM523 and NCM622 batteries using a two-dimensional analysis model. The results show that the two-dimensional simulation results are generally matched with three-dimensional simulation. Also, In the case of NCM111 with a low Ni content in the temperature range used in this study, thermal runaway phenomenon does occurred very slowly, but as the Ni content is increased, the thermal runaway phenomenon occurs rapidly and the thermal stability tends to be decreased. And, in NCM523 and NCM622 batteries, chain reactions occur almost simultaneously, but in the case of NCM111 battery, it is found that after the SEI(Solid Electrolyte Interface) layer decomposition reaction, the cathode-electrolyte reaction is appeared sequentially. After that, the anodic decomposition reaction is increased and leads to the thermal runaway reaction.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.85-94
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• 2022

To detect anomaly signs of thermal runaway in advance, this study analyzed the signals from various sensors installed in lithium-ion batteries. The thermal runaway mechanism was analyzed, and measurement variables for anomalies of a battery cell were surface temperature, strain, and gas concentration. The changes and characteristics of three variables during the thermal runaway process were analyzed under the abuse environment: the overheat and the overcharge. In experiment, the thermal runaway of the battery proceeded in the initial developing stage, the outgassing stage, and the ignition stage. Analysis from the measured data indicated that the suitable variable to detect all stages of thermal runaway is the surface temperature of the battery, and surface strain is alternative.

• 한국전자파학회논문지
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• 제10권6호
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• pp.910-916
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• 1999

This paper presents the effective improvement of the thermal runaway phenomenon in high power SSPA when the RF input signal is not provided. The total gate resistors are optimized by the experiments and deducing the variation of velocity and currents of thermal runaway, which is based on manufacturer's recommendation. Especially, it is solved the complex thermal runaway that related gate resistors with the gate voltage variable circuit. The result of this paper is able to apply for improving the thermal runaway in existence of high power SSPA for WLL, cellular system and PCS repeater.

• 한국안전학회지
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• 제36권5호
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• pp.1-9
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• 2021

With the convergence of the information and communication technologies, a new age of technological civilization has arrived. This is the age of intelligent revolution, known as the 4th industrial revolution. The 4th industrial revolution is based on technological innovations, such as robots, big data analysis, artificial intelligence, and unmanned transportation facilities. This revolution would interconnect all the people, things, and economy, and hence will lead to the expansion of the industry. A high-density, high-capacity energy technology is required to maintain this interconnection. As a next-generation energy source, lithium-ion batteries are in the spotlight today. However, lithium-ion batteries can cause thermal runaway and fire because of electrical, thermal, and mechanical abuse. In this study, thermal runaway was induced in 72.5 Ah NCM pouch-type lithium-ion batteries because of thermal abuse. The surface of the pouch-type lithium-ion batteries was heated by the hot plate heating method, and the effect of the rate of increase in the surface temperature on the thermal runaway trigger time was analyzed using Minitab 19, a statistical analysis program. The correlation analysis results confirmed that there existed a strong negative relationship between each variable, while the regression analysis demonstrated that the thermal runaway trigger time of lithium-ion batteries can be predicted from the rate of increase in their surface temperature.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.120-125
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• 2011

SPDs are increasingly being used against lightning and switching surge according to the applicable revised standard and equipotential grounding system. SPDs are equipped usually with a MOV voltage regulating element. The MOV, however, always is exposed to the danger of thermal runaway resulting from inrushing temporary overvoltage and deterioration. In this paper, the authors made two prototype SPDs built-in Instantaneous trip device and analyzed their limiting voltage through test of the MOV breakdown. As the result of the analysis, the SPDs built-in Instantaneous trip device was proven to be effective for protecting MOV against thermal runaway and Instantaneous trip device react for limiting voltage is considered that is applicable to SPD.

• 한국안전학회지
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• 제26권5호
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• pp.46-53
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• 2011

The risk assessment of thermal behavior and runaway reaction cased by an exothermic batch process in manufacture of the vinyl acetate resin are described in the present paper. The aim of the study was to evaluate the risk of runaway reaction with operating parameters such as a reaction inhibitor, reaction temperature and a mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed by a sort of calorimetry with the Multimax reactor system as a screening tool to investigate runaway reaction. From the experimental results, it was found that we could occur the auto acceleration for reaction of raw materials with operating parameters over $65^{\circ}C$ of reaction temperature in the vinyl acetate polymerization process.

• 한국지열·수열에너지학회논문집
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• 제17권4호
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• pp.46-58
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• 2021

As accidents with thermal runaway (TR) of lithium-ion batteries occur sporadically, the safety concern is the main obstacle that hinders the large-scale applications of lithium ion batteries. In most accidents, the TR of a single cell occurred first, and then dissipated the heat to the surroundings and triggered the TR of adjacent cells, resulting in TR propagation. Therefore, it is important to understand the mechanism of TR propagation and determine the key parameters during TR propagation in a battery pack. In this study, we performed a numerical analysis on the thermal runaway phenomenon by cathode active materials and appearance sizes in cylindrical lithium-ion batteries using a two-dimensional analysis model. The model results showed that the TR propagation of 21700 type cells (21 mm diameter, 70 mm height) occurs more rapidly than 46800 type cells (46 mm diameter, 80 mm height) and the LFP cell has higher thermal safety than the NCM cell. Especially, we found that the effect of the separator on the occurrence of TR is negligible.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.353-356
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• 2007

This paper presents the thermal and electrical characteristics of ZnO arrester blocks under the AC voltages. The leakage currents of ZnO arrester blocks were measured as a function of time. The temperature distributions of ZnO arrester blocks were observed by the forward looking infrared camera The degradation and thermal runaway of ZnO arrester blocks were closely related with the temperature limit of ZnO arrester blocks which decided heat generation and dissipation As a result, the degradation and thermal runaway of ZnO arrester blocks depend on the temperature and leakage current of ZnO arrester blocks.