New social risks, Korean families, and policy challenges

노트 : Paper to be presented in the Panel‘New Social Risks and New Family - Changing Paradigm of Asian Way of Welfare?’The 4th Annual East Asian Social Policy research network International ConferenceUniversity of Tokyo, Tokyo, JapanOctober 20 - 21, 200

Exploring Nanoscale Optoelectronic Properties of Kesterite- and Perovskite-based Devices

Emerging photovoltaic materials such as kesterite and perovskite for optoelectronic devices have inevitable defects that affect the device performance. Therefore, examining the optoelectronic properties of defects is crucial to improve the device performance. Scanning probe microscopy (SPM) is one of the essential techniques to investigate various properties of materials at nanoscale with high resolution. This thesis focuses on characterising kesterite and perovskite using SPM technique to elucidate nanoscale charge transport properties. This primary objective of the first part of this thesis is to understand the effect of compositional variation of kesterite on optoelectronic properties at nanoscale by controlling tin content during the precursor process. This work demonstrated the highest A-type [ZnCu + VCu] defect and altered distribution of sulfur with high near-surface accumulation at an optimised compositional ratio. This synergetic outcome facilitated carrier separation across grain boundaries (GBs). Moreover, the open-circuit voltage deficit was significantly reduced at an optimum compositional ratio owing to improving charge transport through GBs, thereby exhibiting an improved power conversion efficiency. Furthermore, this thesis examines the effect of passivation strategies in halide perovskite for indoor applications using phenethylammonium iodide (PEAI) and lead(II) chloride (PbCl2). A homogenous charge separation across a surface of perovskite was observed when an adequate amount of PEAI was deposited on the perovskite surface. In addition, incorporation of PbCl2 facilitated effective charge transport through GBs. Both strategies facilitated carrier transport towards the surface of perovskite with less ion migration and reduced non-radiative recombination, thereby improving the performance of indoor perovskite solar cells. Finally, another aspect of this thesis is to investigate the optoelectronic properties of two-dimensional perovskite single crystal (butylammonium lead bromide, BA2PbBr4) and elucidate their effect of these optoelectronic properties on the performance of photodetectors (PDs). Accumulation of charge carriers increased at edges with increasing the edge height. Furthermore, the existence of multiple sub-bandgap states in BA2PbBr4, and increasing electron transitions from sub-bandgap states with higher edge height were observed with increasing edge height. This work suggests that edge-height dependence of charge-carrier behaviour in BA2PbBr4 can be utilised in broadband PDs

Writing Instruction in the Middle Grades: A Cross-Cultural Inquiry of Teacher Perceptions and Practices in South Korea and the United States

Despite its importance in promoting student academic achievement and career development, writing pedagogy has received little emphasis in research and professional development efforts. The purpose of this study was to examine teacher perceptions and practices of writing in the middle grades from a cross-cultural perspective. 16 middle-grade teachers from South Korea and one state within the United States were recruited for a semi-structured interview. Transcripts of the interview responses were analyzed, using a constant comparison method. The findings showed that teachers’ instructional practices in writing were contextualized with their personal and professional knowledge and experiences. Country specific patterns were found in teacher perceptions of best practices in writing instruction while cross-cultural patterns were observed in the ways that teachers differentiated instruction for struggling writers and motivated them to write

Threatened or Threatening?: Securitization of the Yemeni Asylum Seekers in South Korea

The arrival of many Yemeni people on Jeju Island in 2018 to seek asylum became a mega-political issue in South Korea. This article investigates two questions. First, how and why have Yemeni asylum seekers suddenly become the focus of securitization concerns in South Korea? And second, how have these concerns affected the governments responses? We argue that three key factors—the influence of media on the refugee crisis in Europe, the Yemenis race, gender, and religious background, and South Koreas internal political and economic situation—have intersected with each other and produced the securitization of Yemeni migration. Amidst highly contested political debates on the protection of forced migrants in South Korea, the state has strictly controlled the border but showed contradictory refugee policies

Acm1 is a negative regulator of the Cdh1-dependent anaphase-promoting complex/cyclosome in budding yeast

Cdh1 is a coactivator of the anaphase-promoting complex/cyclosome (APC/C) and contributes to mitotic exit and G(1) maintenance by facilitating the polyubiquitination and subsequent proteolysis of specific substrates. Here, we report that budding yeast Cdh1 is a component of a cell cycle-regulated complex that includes the 14-3-3 homologs Bmh1 and Bmh2 and a previously uncharacterized protein, which we name Acm1 (Apc/c(Cdh1) modulator 1). Association of Cdh1 with Bmh1 and Bmh2 requires Acm1, and the Acm1 protein is cell cycle regulated, appearing late in G(1) and disappearing in late M. In acm1 Delta strains, Cdh1 localization to the bud neck and association with two substrates, Clb2 and Hsl1, were strongly enhanced. Several lines of evidence suggest that Acm1 can suppress APC/C-Cdh1-mediated proteolysis of mitotic cyclins. First, overexpression of Acm1 fully restored viability to cells expressing toxic levels of Cdh1 or a constitutively active Cdh1 mutant lacking inhibitory phosphorylation sites. Second, overexpression of Acm1 was toxic in sic1 Delta cells. Third, ACM1 deletion exacerbated a low-penetrance elongated-bud phenotype caused by modest overexpression of Cdh1. This bud elongation was independent of the morphogenesis checkpoint, and the combination of acm1 Delta and hsl1 Delta resulted in a dramatic enhancement of bud elongation and G(2)/M delay. Effects on bud elongation were attenuated when Cdh1 was replaced with a mutant lacking the C-terminal IR dipeptide, suggesting that APC/C-dependent proteolysis is required for this phenotype. We propose that Acm1 and Bmh1/Bmh2 constitute a specialized inhibitor of APC/C-Cdh1

Primary segmental volvulus of the ileum mimicking meconium plug syndrome

Primary segmental volvulus (PSV) of the ileum in neonate occurs rarely but shows an aggressive clinical course. Thus, early diagnosis is important to prevent necrosis and perforation of the intestine. We report a case of PSV of the ileum in a 2-day-old female neonate whose clinical features and radiologic findings appeared to be meconium plug syndrome

Characterization of eight novel proteins with male germ cell-specific expression in mouse

<p>Abstract</p> <p>Background</p> <p>Spermatogenesis and fertilization are highly unique processes. Discovery and characterization of germ cell-specific genes are important for the understanding of these reproductive processes. We investigated eight proteins encoded by novel spermatogenic cell-specific genes previously identified from the mouse round spermatid UniGene library.</p> <p>Methods</p> <p>Polyclonal antibodies were generated against the novel proteins and western blot analysis was performed with various protein samples. Germ cell specificity was investigated using testes from germ cell-less mutant mice. Developmental expression pattern was examined in testicular germ cells, testicular sperm and mature sperm. Subcellular localization was assessed by cell surface biotin labeling and trypsinization. Protein localization and properties in sperm were investigated by separation of head and tail fractions, and extractabilities by a non-ionic detergent and urea.</p> <p>Results</p> <p>The authenticity of the eight novel proteins and their specificity to spermatogenic cells were confirmed. In examining the developmental expression patterns, we found the presence of four proteins only in testicular germ cells, a single protein in testicular germ cells and testicular sperm, and three proteins in the testicular stages and mature sperm from the epididymis. Further analysis of the three proteins present in sperm disclosed that one is located at the surface of the acrosomal region and the other two are associated with cytoskeletal structures in the sperm flagellum. We name the genes for these sperm proteins Shsp1 (Sperm head surface protein 1), Sfap1 (Sperm flagellum associated protein 1) and Sfap2 (Sperm flagellum associated protein 2).</p> <p>Conclusion</p> <p>We analyzed eight novel germ cell-specific proteins, providing new and inclusive information about their developmental and cellular characteristics. Our findings will facilitate future investigation into the biological roles of these novel proteins in spermatogenesis and sperm functions.</p

Decoupling Bimolecular Recombination Mechanisms in Perovskite Thin Films Using Photoluminescence Quantum Yield

We present a novel analytical model for analysing the spectral photoluminescence quantum yield of non-planar semiconductor thin films. This model considers the escape probability of luminescence and is applied to triple-cation perovskite thin films with a 1-Sun photoluminescence quantum yield approaching 25%. By using our model, we can decouple the internal radiative, external radiative, and non-radiative bi-molecular recombination coefficients. Unlike other techniques that measure these coefficients separately, our proposed method circumvents experimental uncertainties by avoiding the need for multiple photoluminescence measurement techniques. We validate our model by comparing the extracted implied open-circuit voltage, effective luminescence escape probabilities, absorptivity, and absorption coefficient with values obtained using established methods and found that our results are consistent with previous findings. Next, we compare the implied 1-Sun radiative open-circuit voltage and radiative recombination current obtained from our method with literature values. We then convert the implied open-circuit voltage and implied radiative open-circuit voltage to the injection-dependent apparent-effective and apparent-radiative carrier lifetimes, which allow us to decouple the different recombination coefficients. Using this lifetime analysis, we predict the efficiency losses due to each recombination mechanism. Finally, by comparing several different thicknesses, we conclude that the non-radiative bimolecular recombination is likely caused by surface recombination. Our proposed analytical model provides a reliable method for analysing the spectral photoluminescence quantum yield of semiconductor thin films, which will facilitate further research into the photovoltaic properties of these materials.Comment: Main text: 11 figures, 7 tables Supplemental Material: 42 figures, 7 table

Decoupling Bimolecular Recombination Mechanisms in Perovskite Thin Films Using Photoluminescence Quantum Yield

We present a novel analytical model for analysing the spectral photoluminescence quantum yield of non-planar semiconductor thin films. This model considers the escape probability of luminescence and is applied to triple-cation perovskite thin films with a 1-Sun photoluminescence quantum yield approaching 25%. By using our model, we can decouple the internal radiative, external radiative, and non-radiative bi-molecular recombination coefficients. Unlike other techniques that measure these coefficients separately, our proposed method circumvents experimental uncertainties by avoiding the need for multiple photoluminescence measurement techniques. We validate our model by comparing the extracted implied open-circuit voltage, effective luminescence escape probabilities, absorptivity, and absorption coefficient with values obtained using established methods and found that our results are consistent with previous findings. Next, we compare the implied 1-Sun radiative open-circuit voltage and radiative recombination current obtained from our method with literature values. We then convert the implied open-circuit voltage and implied radiative open-circuit voltage to the injection-dependent apparent-effective and apparent-radiative carrier lifetimes, which allow us to decouple the different recombination coefficients. Using this lifetime analysis, we predict the efficiency losses due to each recombination mechanism. Our proposed analytical model provides a reliable method for analysing the spectral photoluminescence quantum yield of semiconductor thin films, which will facilitate further research into the photovoltaic properties of these materials

Surface Saturation Current Densities of Perovskite Thin Films from Suns-Photoluminescence Quantum Yield Measurements

We present a simple, yet powerful analysis of Suns-photoluminescence quantum yield measurements that can be used to determine the surface saturation current densities of thin film semiconductors. We apply the method to state-of-the-art polycrystalline perovskite thin films of varying absorber thickness. We show that the non-radiative bimolecular recombination in these samples originates from the surfaces. To the best of our knowledge, this is the first study to demonstrate and quantify non-linear (bimolecular) surface recombination in perovskite thin films