Effects of Minimum Wage Increase on Employment in Small and Medium-sized Enterprises in Korea

In Korea, where SMEs dominantly provide most of the jobs in labor market, how SMEs respond to an increase in the minimum wage in terms of employment can be a critical factor of job provision in Korean labor market. This paper mainly examines the effect of the minimum wage increase on employment in SMEs in Korea by using a difference-in-differences methodology, and finds that raising the minimum wage has on average significantly reduced total employment in all sizes of SMEs relative to large enterprises. The finding in this paper suggests that raising the minimum wage rate may incur loss of jobs in Korean labor market

Three-Dimensional Metal-Oxide Nanohelix Arrays Fabricated by Oblique Angle Deposition: Fabrication, Properties, and Applications

Three-dimensional (3D) nanostructured thin films have attracted great attention due to their novel physical, optical, and chemical properties, providing tremendous possibilities for future multifunctional systems and for exploring new physical phenomena. Among various techniques to fabricate 3D nanostructures, oblique angle deposition (OAD) is a very promising method for producing arrays of a variety of 3D nanostructures with excellent controllability, reproducibility, low cost, and compatibility with modern micro-electronic processes. This article presents a comprehensive overview of the principle of OAD, and unique structural and optical properties of OAD-fabricated thin films including excellent crystallinity, accurate tunability of refractive indices, and strong light scattering effect which can be utilized to remarkably enhance performances of various systems such as antireflection coatings, optical filters, photoelectrodes for solar-energy-harvesting cells, and sensing layers for various sensors.1114Ysciescopu

The Social Networks of Korean Female Adult Learners in a Middle School

This study investigates the social networks of Korean female adult learners in middle school through social network analysis and examines the development of these networks by interviewing the main actors involved

Longitudinal Association Between Children’s Callous-Unemotional Traits and Social Competence: Child Executive Function and Maternal Warmth as Moderators

This study examined the longitudinal association between children’s early callous-unemotional (CU) traits and social competence in the transition to school-age, and tested whether this relationship was moderated by child executive function and maternal warmth. Participants were 643 children (49% girls) who were part of the Panel Study on Korean Children (PSKC) of the Korea Institute of Child Care and Education (KICCE). Mothers rated children’s CU at 5 years and executive function at 8 years, and maternal warmth at 5 years. Teachers reported on children’s social competence at 8 years. Results of the model including child executive function as the moderator indicated that deficits in child executive function and child sex (boys) predicted lower social competence. In addition, the moderating effect of executive function on the relationship between CU and social competence approached a trend such that CU predicted lower social competence only for children with lower executive function. In the model that included maternal warmth as a moderator, CU traits was associated with lower social competence, and this effect was more pronounced for boys as indicated by a significant effects of CU × child sex on social competence. The findings are discussed with respect to considering individual and contextual factors by which early CU becomes associated with individual differences in children’s social competence

Coordination tuning of cobalt phosphates towards efficient water oxidation catalyst

The development of efficient and stable water oxidation catalysts is necessary for the realization of practically viable water-splitting systems. Although extensive studies have focused on the metal-oxide catalysts, the effect of metal coordination on the catalytic ability remains still elusive. Here we select four cobalt-based phosphate catalysts with various cobalt-and phosphate-group coordination as a platform to better understand the catalytic activity of cobalt-based materials. Although they exhibit various catalytic activities and stabilities during water oxidation, Na2CoP2O7 with distorted cobalt tetrahedral geometry shows high activity comparable to that of amorphous cobalt phosphate under neutral conditions, along with high structural stability. First-principles calculations suggest that the surface reorganization by the pyrophosphate ligand induces a highly distorted tetrahedral geometry, where water molecules can favourably bind, resulting in a low overpotential (similar to 0.42 eV). Our findings emphasize the importance of local cobalt coordination in the catalysis and suggest the possible effect of polyanions on the water oxidation chemistry.

Establishment of feeder-free culture system for human induced pluripotent stem cell on DAS nanocrystalline graphene

The maintenance of undifferentiated human pluripotent stem cells (hPSC) under xeno-free condition requires the use of human feeder cells or extracellular matrix (ECM) coating. However, human-derived sources may cause human pathogen contamination by viral or non-viral agents to the patients. Here we demonstrate feeder-free and xeno-free culture system for hPSC expansion using diffusion assisted synthesis-grown nanocrystalline graphene (DAS-NG), a synthetic non-biological nanomaterial which completely rule out the concern of human pathogen contamination. DAS-NG exhibited advanced biocompatibilities including surface nanoroughness, oxygen containing functional groups and hydrophilicity. hPSC cultured on DAS-NG could maintain pluripotency in vitro and in vivo, and especially cell adhesion-related gene expression profile was comparable to those of cultured on feeders, while hPSC cultured without DAS-NG differentiated spontaneously with high expression of somatic cell-enriched adhesion genes. This feeder-free and xeno-free culture method using DAS-NG will facilitate the generation of clinical-grade hPSC.ope