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서영빈 ( Youngbin Seo ),송헌재 ( Heonjae Song ) 한국경제학회 2023 한국경제포럼 Vol.16 No.2
본 연구는 2009년부터 2019년의 한국노동패널 자료와 고용형태별근로실태조사 자료를 사용하여 산업의 여성 비율이 임금에 미치는 영향을 분석하였다. 고정효과모형을 통해 임금 함수를 추정한 주요 결과를 요약하면 다음과 같다. 첫째, 산업의 여성 비율이 증가할수록 임금에 부정적 영향을 미치는 것으로 나타났다. 둘째, 산업의 여성 비율 증가가 여성의 임금보다 남성의 임금에 미치는 부정적인 효과가 더 크게 나타났다. 이러한 결과는 개인의 성향 및 능력보다 근로자가 축적한 인적자본의 차이로 인해 발생했다고 볼 수 있다. 노동시장 진입 이전에 높은 인적자본을 축적하였으나 여성의 경력 단절 이후 낮은 수준에서 형성된 임금으로 인해 노동시장에 재진입하지 않은 결과일 수도 있다. 본 연구의 결과는 산업의 여성 비율 증가가 저임금을 유발하는 현상을 제시하여 여성의 노동시장의 질적 개선과 성별 임금 격차 해결을 위한 노력의 필요성을 강조하는 것으로 해석할 수 있다. This study analyzes the effects of the female ratio in industries on wages using the Korean Labor and Income Panel (KLIPS) from 2009 to 2019 and the Korean Survey Report on Labor Conditions by Employment Type. The main estimation results are summarized as follows. First, the higher the female ratio in industries, the more negatively it affects wages. Second, as the proportion of woman in the industry increases, men’s wages decrease more than women’s wages. These results can be attributed to differences in human capital accumulated by workers rather than individual abilities. We suspect that the reason of these results are the labor choice of Korean women with high human capital who entered high paying jobs hesitate to renter a labor market due to the low expected wages after women’s career break, and it might cause this phenomenon. The results of the study suggest that the quality of women's labor market should be improved and we need to make significant efforts to resolve the gender wage gap.
Youngbin Song,Minhwan Seo,Shina Park,Sang W. Kim 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
Initial parameter variances between cells in battery packs occur in a manufacturing process. Furthermore, this difference is intensified as the pack is being used, resulting in differences in capacity and the state of charge (SOC) between cells. Cell inconsistencies decrease the energy efficiency, and low-capacity cells in packs can occur an internal short circuit (ISC) fault which causes a thermal runaway in severe cases. However, the ISC may be misdiagnosed as cell inconsistencies and vice versa because the impacts of cell inconsistencies and the ISC are similar in particular charge/discharge. In this paper, a model-based cell inconsistency classification method is proposed. The equivalent circuit model of the fresh cell is used as a reference model, making it possible to save efforts in constructing parameter look-up tables for various degrees of aging. In addition, we use the SOC difference feature that can clearly distinguish the effects of inconsistencies and ISC using the reference SOC calculated by the nominal capacity. The proposed method was verified in simulation for various types and degrees of cell inconsistencies and ISC, and accurately identified inconsistent cells and ISC cells, thereby leading to efficient energy use and early detection of the ISC fault.
셀 밸런싱 동작을 고려한 리튬 이온 배터리 팩의 내부 단락 고장 진단
송영빈(Youngbin Song),서민환(Minhwan Seo),박신아(Shina Park),김상우(Sang Woo Kim) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
리튬 이온 배터리의 효율적이고 안전한 사용을 위해 내부 단락 고장 검출은 필수적이다. 고전력을 필요로 하는 어플리케이션에서 사용하는 배터리 팩의 경우 팩 내 셀 간 전압을 균일하게 맞춰주는 셀 밸런싱을 수행한다. 배터리에 병렬로 연결된 저항을 통해 전류를 소산시켜 셀 간 전압 편차를 최소화하는 셀 밸런싱은 내부 단락 고장의 누설 전류와 유사한 동작을 수행하므로 내부 단락 고장 오검출의 원인이 된다. 따라서 본 연구에서는 셀 밸런싱이 동작하는 배터리 팩에서 정확한 고장 셀을 검출하는 모델 기반 내부 단락 고장 검출 방법을 제안한다. 확장 칼만 필터를 통해 측정 셀 전압과 부하 전류로 고장 검출을 위한 feature를 추출하고, 최소 제곱법 알고리즘을 사용하여 고장 셀의 위치 및 고장 정도를 추정한다. MATLAB/Simulink 기반 배터리팩 시뮬레이터를 구현하여 셀 밸런싱 및 내부 단락 고장 조건에서의 시뮬레이션 데이터를 획득하였고, 이를 이용하여 제안 알고리즘을 검증하였다.
Baek, Youngbin,Seo, Dong Kyun,Choi, Jong Ho,Lee, Byeongho,Kim, Yong Hyup,Park, Seung Min,Jung, Jungwoo,Lee, Sangho,Yoon, Jeyong Taylor Francis 2016 Desalination and Water Treatment Vol.57 No.58
<P>Carbon nanotube (CNT) membranes are considered as next-generation membranes for desalination. Among the various types of CNT membranes, vertically aligned (VA) CNT membranes provide rapid water transport. However, when the water permeability of VA CNT membranes are compared with those of the commercial membrane, the VA CNT membranes only showed slightly higher water permeability due to their low pore densities. Additionally, the applicability of VA CNT membranes for desalination has been limited due to their larger pore sizes. Herein, we improved VA CNT membranes in terms of the desalination potential, flux enhancement, and scale-up. For the desalination potential, graphene oxide (GO) or polyamide (PA) were coated on a VA CNT membrane as a selective layer, which showed approximately 40-65% NaCl rejection, respectively. A pretreatment polyelectrolyte coating for a GO-coated VA CNT membrane increased the water permeability by approximately 50%. For the flux enhancement, the water permeability of a VA CNT membrane was nearly doubled when the VA CNT forest was mechanically densified by half. Finally, an enlarged VA CNT forest (2 x 2 cm(2)), sequential VA CNT forests (1 x 1 cm(2)) in a large cast, and an assembly of the VA CNT membrane were suggested as scale-up approaches.</P>
Capacity estimation of lithium-ion batteries under various temperatures using two aging indicators
Minhwan Seo,Youngbin Song,Shina park,Sang Woo Kim 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
Lithium-ion batteries undergo calendar aging and cycle aging, respectively, during storage and usage, and their capacity (an important factor for efficient and safe use of batteries) gradually decreases. Additionally, ambient temperature changes capacity of the battery. Existing methods developed for a specific temperature are difficult to apply to batteries under different temperatures. This study proposes a method to easily estimate capacities of batteries at various temperatures and aging conditions using two aging indicators. Electrochemical characteristics of the battery, which change according to battery aging, can be extracted through measured surface temperatures, terminal voltages, and currents: 1) One is change in entropy of the battery and 2) the other is change in internal resistance of the battery. It is confirmed that two aging indicators (entropy and internal resistance) have a linear relationship with battery aging through the experimental data, and that the linear relationship maintains the identical trend even at various temperatures. The results of estimating the battery capacities using the two aging indicators demonstrate that relative errors are less than 3.11%. Therefore, the proposed method can accurately estimate capacities of batteries in different temperature and aging conditions, and can be easily applied to batteries in various temperature environments.