• 반도체디스플레이기술학회지
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• 제13권1호
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• pp.101-108
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• 2014

The battery pack in this research consists of dozens of a small battery for energy storage. And this battery pack charges and discharges repeatedly at high capacity (25 ~ 50 V, 25 ~ 100 A). The high temperature which can be generated in this process has a bad effect to the lifetime and efficiency of batteries. Moreover these factors are related with maintenance cost. Therefore, we need to assess the thermal performance of the battery pack in advance using the experimental or numerical analysis. In this research, we analyzed voltage and surface temperature of one cell battery to calculate heat transfer using the numerical analysis. And the temperature of the battery surfaces and inside of the pack was also analyzed. As a result, we found out the appropriate pack structure which stacked five modules.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.363-364
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• 2017

This paper analyzes switching losses and efficiency depending on SiC and Si devices applied in 3-phase AC/DC Converter for Battery Pack Testing System. The switch elements of the 3-phase AC/DC Converter is compared to Si and SiC-based elements and analyzed through comparison of each switching loss by simulation results.

• 전력전자학회논문지
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• 제24권1호
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• pp.16-24
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• 2019

The performance of the battery management system (BMS) algorithm is important for ensuring the stability and efficient operation of battery packs. Such a performance is determined by the internal parameters of the electrical equivalent circuit model (EECM). This study proposes a performance improvement and verification of battery parameters for the BMS algorithm using electrical experiments and tools. The parameters were extracted through electrical characteristic experiments, and an EECM based on Ah counting was designed. Simulation results using the EECM were compared with actual experimental data to determine the best parameter extraction method.

• 한국수소및신에너지학회논문집
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• 제31권5호
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• pp.489-497
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• 2020

The Li-ion battery is considered to be one of the potential power sources for electric vehicles. In fact, the efficiency, reliability, and cycle life of Li-ion batteries are highly influenced by their thermal conditions. Therefore, a novel thermal management system is highly required to simultaneously achieve high performance and long life of the battery pack. Basically, thermal modeling is a key issue for the novel thermal management of Li-ion battery systems. In this paper, as a basic study for battery thermal modeling, temperature distributions inside the simple Li-ion battery pack (comprises of nine 18650 Li-ion batteries) under a 1C discharging condition were investigated using measurement and computational fluid dynamics (CFD) simulation approaches. The heat flux boundary conditions of battery cells for the CFD thermal analysis of battery pack were provided by the measurement of single battery cell temperature. The temperature distribution inside the battery pack were compared at six monitoring locations. Results show that the accurate estimation of heat flux at the surface of single cylindrical battery is paramount to the prediction of temperature distributions inside the Li-ion battery under various discharging conditions (C-rates). It is considered that the research approach for the estimation of temperature distribution used in this study can be used as a basic tool to understand the thermal behavior of Li-ion battery pack for the construction of effective battery thermal management systems.

• 마이크로전자및패키징학회지
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• 제29권3호
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• pp.13-23
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• 2022

환경이슈로 인해 전기자동차에 대한 수요 및 관심이 급증하고 있다. 전기자동차의 성능 향상에는 핵심 부품인 자동차 배터리의 성능향상, 그리고 배터리 접합기술의 발전이 수반되어야 한다. 알루미늄 합금은 전기자동차 산업에서 가장 폭넓게 사용되는 금속이며, 알루미늄 접합은 전기자동차 이차전지를 구성하는 모든 공정에서 이용된다. 따라서 본 논문에서는 알루미늄, 알루미늄 합금의 특성과 다양한 알루미늄 접합 기술에 대한 지식을 기반으로, 차량용 이차전지에서 이용되는 주요한 접합기술과 차세대 접합기술을 검토한다. 또한 그 과정에서 접합이 이용되는 자동차 이차전지 셀의 구조, '셀-모듈-팩'의 집적 순서와, 접합 기술이 요구하는 다양한 환경적 조건들을 설명한다.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 1부
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• pp.429-434
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• 2007

본 논문에서는 기울임 동작에 기반한 휴대기기 상의 사진 감상 UI를 제시하고 사용성을 평가한다. 기존의 기울임 입력 방식의 세가지 조작성 문제(overshooting, fluctuation, 부분 이미지 제시)를 개선하기 위하여, 사진 위치 및 기울임에 의존하는 사진 이동 제어 dynamics 모델을 제안한다. 본 시스템은 기울임 감지용 가속도 센서, 기울임에 의한 사진 이동 제어 dynamics 모델, 다중모달(시각, 청각, 촉각)을 통한 모델 상태 출력부로 구성된다. 센서 입력과 다중 모달 출력을 위하여, 삼성 MITs 4300 PDA의 배터리 팩을 개조하여 3축 가속도 센서와 진동 출력장치 (VBW32)를 장착하였다. 제안하는 시스템은 기존의 대표적인 사진 감상 입력 방법인 버튼과 iPod wheel과 비교하였다. 정량적 비교를 위하여 7명의 사용자에게 100장의 사진 중 20장을 차례로 검색하는 과제를 부여하면서 수집한 로그를 분석하였으며, 정성적인 비교를 위하여 설문 조사를 실시하였다. 실험 결과 제안한 방법이 기존 기울임 기반 dynamics에 비하여 overshooting 횟수를 30%, 사진간 이동 거리를 25%, 이동 시간을 17% 감소하였다. 또한 제안한 방법이 버튼과 유사한 조작성을 갖고 있으며, 버튼과 iPod보다 더욱 흥미성이 뛰어났다. 상업적으로 뛰어난 성공을 거둔 iPod이 다수의 overshooting 발생으로 실제로는 사용성이 떨어진다는 점이 예상치 못한 흥미로운 발견이었다.

• 한국전기전자재료학회논문지
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• 제31권7호
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• pp.515-520
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• 2018

A large number of lithium-ion batteries are arranged in series and parallel in battery packs, such as those in electric vehicles or energy storage systems. As battery packs age, their output power and energy density drop because of voltage deviation, constant and non-uniform exposure to abnormal environments, and increased contact resistance between batteries; this reduces application system efficiency. Despite the balancing circuit and logic of the battery management system, the output of the battery pack is concentrated in the most severely aged unit cell and the output is frequently limited by power derating. In this study, we implemented a cell imbalance detection algorithm and selected parameters to detect a sudden decrease in battery pack output. In addition, we propose a method to increase efficiency by applying the measured testing values considering the operating conditions and abnormal conditions of the battery pack.

• 전력전자학회논문지
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• 제23권6호
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• pp.408-414
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• 2018

Given that lithium-ion batteries are expected to be used as power sources for electric and hybrid vehicles, thermodynamics experimentation and prediction based on experimental data were performed. Thermal, electrochemical, and electrochemical/electrical-thermal models were used for accurate battery modeling. Various applications of different battery packs were demonstrated, and thermal analysis was performed using the same experimental conditions for square and rectangular battery packs. Accurate thermal analysis for a single cell should be prioritized to determine the thermal behavior of the battery pack. The energy balance equation, which contains heat generation and heat transfer factors, defines the thermal behavior of the battery pack. By comparing battery packs of different shapes tested under the same condition, this study revealed that the rectangular battery pack is superior to the square battery pack in terms of the maximum temperature of inner cells and temperature variation between cells.

• 전력전자학회논문지
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• 제26권6호
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• pp.381-389
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• 2021

Most diagnosis approaches rely on historical failure data that might not be feasible in real operating conditions because the battery voltage and internal parameters are nonlinear according to various operating conditions, such as cell-to-cell configuration and initial condition. To overcome this issue, the estimator and the predictor require integrated approaches that consider comprehensive data, with the degradation process and measured data taken into account. In this paper, vector autoregressive models (VAR) with various parameters that affect overdischarge to the cell in the battery pack were constructed, and the cell-to-cell parameters were identified using an adaptive model to analyze the influence of failure prognosis. The theoretical analysis is validated using experimental results in terms of the feasibility and advantages of fault prognosis.

• 전력전자학회논문지
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• 제26권6호
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• pp.390-396
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• 2021

Lithium-ion batteries have been designed and used as battery packs with series and parallel combinations that are suitable for use. However, due to its internal electrochemical properties, producing the battery's condition at the same value is impossible for individual cells. In addition, the management of characteristic deviations between individual cells is essential for the safe and efficient use of batteries as aging progresses with the use of batteries. In this work, we propose a method to manage deviation properties and detect abnormal behavior in the configuration of a combined battery pack of these multiple battery cells. The proposed method can separate and detect probabilistic low-frequency information according to statistical information based on Z-score. The verification of the proposed algorithm was validated using experimental results from 10S3P battery packs, and the implemented algorithm based on Z-score was validated as a way to effectively manage multiple individual cell information.