• 한국표면공학회지
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• 제57권1호
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• pp.31-37
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• 2024

The surge in demand for lithium is primarily fueled by the expanding electric vehicle market, the necessity for renewable energy storage, and governmental initiatives aimed at achieving carbon neutrality. This study proposes a straightforward method for lithium extraction utilizing cellulose nanofiber (CNF) via a vacuum filtration process. This approach yields a porous CNF film, showcasing its potential utility as a lithium extractor and indicator. Given its abundance and eco-friendly characteristics, cellulose nanofiber (CNF) emerges as a material offering both economic and environmental advantages over traditional lithium extraction techniques. Hence, this research not only contributes to lithium recovery but also presents a sustainable solution to meet the growing demand for lithium in energy storage technologies.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.733-741
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• 2018

Capacity estimation is indispensable to ensure the safety and reliability of lithium-ion batteries in electric vehicles (EVs). Therefore it's quite necessary to develop an effective on-board capacity estimation technique. Based on experiment, it's found constant current charge time (CCCT) and the capacity have a strong linear correlation when the capacity is more than 80% of its rated value, during which the battery is considered healthy. Thus this paper employs CCCT as the health indicator for on-board capacity estimation by means of relevance vector machine (RVM). As the ambient temperature (AT) dramatically influences the capacity fading, it is added to RVM input to improve the estimation accuracy. The estimations are compared with that via back-propagation neural network (BPNN). The experiments demonstrate that CCCT with AT is highly qualified for on-board capacity estimation of lithium-ion batteries via RVM as the results are more precise and reliable than that calculated by BPNN.

• 방사성폐기물학회지
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• 제18권1호
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• pp.83-90
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• 2020

흑연 동위원소 비율법(GIRM)은 비핵화 검증 도구로써 흑연감속로의 플루토늄 생산량을 예측하는데 사용된다. 원자로가 가동되면 ²³⁸U의 중성자 포획 반응에 의해 플루토늄이 생성되어 축적되고 동시에 흑연 내 불순물도 핵반응을 통해 다른 핵종으로 바뀌기 때문에 플루토늄의 생성량과 불순물의 농도는 일정한 상관 관계를 갖는다. 이러한 상관관계에도 불구하고 어느 특정 시점에서의 불순물의 농도는 불순물의 초기 농도에 의존하기 때문에 불순물의 초기 농도가 알려지지 않으면 불순물의 절대 농도만으로 플루토늄 생산량을 예측하는 것은 불가능하다. 그러나 불순물의 초기 동위원소 비율은 초기 불순물 농도에 상관없이 알려져 있기 때문에 불순물의 동위원소 비율과 플루토늄 생산량의 관계는 흑연감속로에서 플루토늄 생성량을 예측하는 유용한 도구가 될 수 있다. 흑연동위원소 비율법의 지표 원소로 Boron, Lithium, Chlorine, Titanium, Uranium 등이 이용되는 것으로 알려져 있다. 위 지표원소의 동위원소 비와 플루토늄 생성량 사이의 상관 관계가 초기 불순물 농도에 의존하지 않는지를 네 가지 다른 흑연 불순물 조성을 이용하여 평가하였다. ¹⁰B/¹¹B, ³⁶Cl/³⁵Cl, ⁴⁸Ti/⁴⁹Ti, ²³⁵U/²³⁸U은 흑연의 초기 불순물 농도에 상관없이 누적 플루토늄 생성량과 일관된 상관 관계를 갖는다. 이러한 원소들은 다른 원소의 핵반응에 의해 해당 원소의 동위원소가 생성되지 않기 때문이다. 반면 ⁶Li/⁷Li과 플루토늄 생성량의 상관관계는 흑연 내 불순물의 초기 농도에 의존한다. ⁷Li은 ⁶Li의 중성자 포획 반응에 의해서 생성되기도 하지만 ¹⁰B의 (n, α)반응으로도 생성되는 것이 더 지배적이기 때문에 ¹⁰B의 초기 농도가 ⁷Li의 생성량에 영향을 미치는 것이다. 따라서 Lithium은 흑연 동위원소 비율법을 위한 지표 원소로 적절하지 않음을 알 수 있다.

• 한국산업융합학회 논문집
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• 제25권6_3호
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• pp.1275-1284
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• 2022

This study provides an investigating the electrolyte reaction characteristics during thermal runaway of a lithium-ion battery(LIB). Dimethyl carbonate(DMC) is known as the main substance that makes up the electrolyte. The mono-molecular decomposition characteristics of DMC were derived through numerical analysis. Cobalt oxide can release oxygen under high temperature conditions. Also, DMC is converted to CH₄, H₂, CO, and CO₂. Especially, it was found that the decomposition of the DMC begins at a temperature range of 340-350℃, which dramatically increases the internal pressure of the LIB. In the by-products gases, the molar ratio of CO and CO₂ changed according to the molecular structure of DMC and temperature conditions. The correlation of the [CO]/[CO₂] ratio according to the temperature during thermal runaway was derived, and the characteristics of the reaction temperature could be estimated using the molar ratio as an indicator. In addition, the oxidation and decomposition characteristics of DMC according to the residence time for each temperature were estimated. When DMC is exposed to low temperature for a long time, both oxidation and decomposition may occur. There is possibility of not only increasing the internal pressure of the LIB, but also promoting thermal runaway. In this study, internal environment of LIB was identified and the reaction characteristics between the active materials of the cathode and electrolyte were investigated.

• 전력전자학회논문지
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• 제25권5호
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• pp.376-384
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• 2020

An energy storage system is composed of lithium-ion batteries in modern applications. Batteries are regarded as storage devices for renewable and residual energy. The failure of batteries can cause the performance reduction and explosion of battery systems. High maintenance cost is essential when dealing with the problem of battery safety. Therefore an accurate health diagnosis is required to ensure the high reliability of battery systems. A battery pack is a combination of single cells in series and parallel connections. A battery pack has to consider various factors to assess battery health. Battery health involves conventional factors and additional factors, such as cell-to-cell imbalance. For large applications, state-of-health (SOH) can be inaccurate because of the lack of factors that indicate the state of the battery pack. In this study, six characterization factors are proposed for improving the SOH estimation of battery packs. The six proposed characterization factors can be regarded as health indicators (HIs). The six HIs are applied to the principal component analysis (PCA) algorithm. To reflect information regarding capacity, voltage, and temperature, the PCA algorithm extracts new degradation factors by using the six HIs. The new degradation factors are applied to a multiple regression model. Results show the advancement and improvement of SOH estimation.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.68-72
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• 2007

A new PVC membrane potentiometric sensor that is highly selective to Hg2+ ions was prepared, using bis(2-hydroxybenzophenone) butane-2,3-dihydrazone (HBBD) as an excellent hexadendates neutral carrier. The sensor works satisfactorily in the concentration range of 1.0 × 10-6 to 1.0 × 10-1 mol L-1 (detection limit 4 × 10-7 mol L-1) with a Nernstian slope of 29.7 mV per decade. This electrode showed a fast response time (~8 s) and was used for at least 12 weeks without any divergence. The sensor exhibits good Hg2+ selectivity for a broad range of common alkali, alkaline earth, transition and heavy metal ions (lithium, sodium, potassium, magnesium, calcium, copper, nickel, cobalt, zinc, cadmium, lead and lanthanum). The electrode response is pH independent in the range of 1.5-4.0. Furthermore, the developed sensor was successfully used as an indicator electrode in the potentiometric titration of mercury ions with potassium iodide and the direct determination of mercury in some binary and ternary mixtures.

• 전기전자학회논문지
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• 제26권1호
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• pp.10-18
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• 2022

정확한 SOC 추정은 배터리 운영 전략을 제시하는 중요한 지표로 많은 연구가 진행되었다. 기존 연구에서 검증을 위해 주로 사용되던 시뮬레이션 방식은 실제 BMS 환경처럼 실시간 SOC를 추정하기 어렵다. 따라서 본 논문에서는 실시간 배터리 SOC 추정이 가능한 임베디드 시스템을 구현하고 검증 과정에서 발생 가능한 문제 분석을 목표로 한다. 2개의 라즈베리파이 보드로 구성된 환경은 Simscape 배터리에서 측정된 데이터로 EKF 기반 SOC 추정을 진행한다. 검증 단계에서는 온도에 따라 달라지는 배터리 특성을 고려하여, 다양한 주변 온도에서 결과를 확인하였다. 또 임베디드 환경에서 발생하는 오프셋 오류와 패킷 손실에 대비하여, 문제 상황에서 SOC 추정 성능을 검증하였다. 이를 통해 안정범위의 5%내의 오차를 갖는 실시간 SOC 추정이 가능한 임베디드 시스템 구현을 위한 전략을 제시한다.