TEMPORARY EMPLOYMENT AND EARNINGS INEQUALITY IN SOUTH KOREA

My dissertation explores the effect of growth of temporary employment on earnings inequality. In the first essay, I find that during a time when there was a nearly 10 percentage points increase in the share of temporary workers in the Korean labor market (but prior to the global recession), the rise in temporary employment can account for a substantial part (20-30 percent) of the growth in overall wage inequality. These results appear to be robust to alternative ways of performing the decomposition, including using the recently developed recentered influence function approach of Firpo, Fortin and Lemieux. In addition, the rise of temporary employment mainly affects the lower-tail of the distribution and fattens the very bottom; female temporary workers in sales and service or doing elementary occupations are the people who suffered from the change the most. In the second essay, joint with Peter Skott, we use an extension of a standard efficiency wage model to explain the wage gap between temporary and permanent workers. Temporary workers have a chance to become permanent; this possibility -- combined with the existence of an employment rent for permanent workers -- gives short-term workers an incentive to work hard. Thus, a high wage to permanent workers serves a dual purpose: it affects the effort of both permanent and temporary workers. Applying the model to the Korean experience, we discuss how institutional changes have contributed to increasing earnings inequality. My third essay explores wage effects of the use of temporary employment upon permanent workers\u27 wage. I propose an idea; as temporary employment grows, the fear of job loss is getting higher and the probability of getting a similar job is getting lower for permanent workers. This lower job insecurity tends to lower their bargaining power, and thus their pay level. Using a firm-level panel, I find that wages for permanent workers decrease as the share of temporary workers increases. The analysis also shows that wages for permanent workers in non-union and small/medium-sized firms have greater negative impacts; this helps explain the evolution of inequality in Korea

Labor Market Reform and Wage Inequality in Korea

Temporary workers make up a sizeable part of the labor force in many countries and typically receive wages that are significantly lower than their permanent counterparts. This paper uses an efficiency wage model to explain the wage gap between temporary and permanent workers. High-performing temporary workers may gain promotion to permanent status, and a high wage to permanent workers therefore serves a dual purpose: it affects the effort of both permanent and temporary workers. Applying the model to the Korean experience, we discuss the effects of the labor market reforms in 1998 on inequality

Technical evolution of liquid crystal displays

Liquid crystal displays (LCDs) have evolved rapidly as a result of fierce competition among the various LCD technologies, and now occupy the largest proportion of the entire display market. The evolution of LCDs continues, with new technologies and new materials in development to replace current devices. This review summarizes the key technologies used in commercially successful LCD products, focusing on the requirements for high-end displays and the benefits of the in-plane switching and multi-domain vertical alignment modes. As in past advances, the development of new materials will play an important role in the continued technical evolution of LCDs.open252

Study on Threat Modeling in Smart Greenhouses

In the era of agriculture 4.0, cutting-edge technologies including Information and communication technology (ICT) is being introduced into traditional agriculture. As farm intelligence emerges as a key area of smart agriculture, the scope of agriculture has expanded from the seed industry to distribution and logistics, however the area that is still most directly connected to the physical agricultural environment is smart farming. Cybersecurity incidents or cybercrimes in smart farming can directly damage crops and harm human safety. Research on individual technical elements that constitute smart farming has been ongoing for a long time relatively, however it has not been long since the work of systematically identifying and classifying threats to smart agriculture as a whole. In this study, STRIDE threat modeling is used to identify cyber threats to greenhouse and make system design more robust. Through this work, we have derived 126 threats and have created 4 types of attack trees. It will be the basis to allow systematic threat classification more clearly in smart greenhouse

Citrus aurantium flavonoids inhibit adipogenesis through the Akt signaling pathway in 3T3-L1 cells

<p>Abstract</p> <p>Background</p> <p>Obesity is a health hazard that is associated with a number of diseases and metabolic abnormalities, such as type-2 diabetes, hypertension, dyslipidemia, and coronary heart disease. In the current study, we investigated the effects of <it>Citrus aurantium </it>flavonoids (CAF) on the inhibition of adipogenesis and adipocyte differentiation in 3T3-L1 cells.</p> <p>Methods</p> <p>During adipocyte differentiation, 3T3-L1 cells were treated with 0, 10, and 50 μg/ml CAF, and then the mRNA and protein expression of adipogenesis-related genes was assayed. We examined the effect of CAF on level of phosphorylated Akt in 3T3-L1 cells treated with CAF at various concentrations during adipocyte differentiation.</p> <p>Results</p> <p>The insulin-induced expression of C/EBPβ and PPARγ mRNA and protein were significantly down-regulated in a dose-dependent manner following CAF treatment. CAF also dramatically decreased the expression of C/EBPα, which is essential for the acquisition of insulin sensitivity by adipocytes. Moreover, the expression of the aP2 and FAS genes, which are involved in lipid metabolism, decreased dramatically upon treatment with CAF. Interestingly, CAF diminished the insulin-stimulated serine phosphorylation of Akt (Ser473) and GSK3β (Ser9), which may reduce glucose uptake in response to insulin and lipid accumulation. Furthermore, CAF not only inhibited triglyceride accumulation during adipogenesis but also contributed to the lipolysis of adipocytes.</p> <p>Conclusions</p> <p>In the present study, we demonstrate that CAF suppressed adipogenesis in 3T3-L1 adipocytes. Our results indicated that CAF down-regulates the expression of C/EBPβ and subsequently inhibits the activation of PPARγ and C/EBPα. The anti-adipogenic activity of CAF was mediated by the inhibition of Akt activation and GSK3β phosphorylation, which induced the down-regulation of lipid accumulation and lipid metabolizing genes, ultimately inhibiting adipocyte differentiation.</p

Is restrictive transfusion sufficient in colorectal cancer surgery? A retrospective study before and during the COVID-19 pandemic in Korea

Purpose Blood transfusion is one of the most common procedures used to treat anemia in colorectal surgery. Despite controversy regarding the adverse effects of blood products, surgeons have maintained standards for administering blood transfusions. However, this trend was restrictive during the COVID-19 pandemic because of a shortage of blood products. In this study, we conducted an analysis to investigate whether the restriction of blood transfusions affected postoperative surgical outcomes. Methods Medical records of 318 patients who underwent surgery for colon and rectal cancer at Ewha Womans University Mokdong Hospital between June 2018 and March 2022 were reviewed retrospectively. The surgical outcomes between the liberal and restrictive transfusion strategies in pre– and post–COVID-19 groups were analyzed. Results In univariate analysis, postoperative transfusion was associated with infectious complications (odds ratio [OR], 1.705; 95% confidence interval [CI], 1.015–2.865; P=0.044). However, postoperative transfusion was not an independent risk factor for the development of infectious complications in multivariate analysis (OR, 1.305; 95% CI, 0.749–2.274; P=0.348). In subgroup analysis, there was no significant association between infectious complications and the hemoglobin threshold level for the administration of a transfusion (OR, 1.249; 95% CI, 0.928–1.682; P=0.142). Conclusion During colorectal surgery, the decision to perform a blood transfusion is an important step in ensuring favorable surgical outcomes. According to the results of this study, restrictive transfusion is sufficient for favorable surgical outcomes compared with liberal transfusion. Therefore, modification of guidelines is suggested to minimize unnecessary transfusion-related side effects and prevent the overuse of blood products

Dectin-1 signaling coordinates innate and adaptive immunity for potent host defense against viral infection

BackgroundMost commercial foot-and-mouth disease (FMD) vaccines have various disadvantages, such as low antibody titers, short-lived effects, compromised host defense, and questionable safety.ObjectivesTo address these shortcomings, we present a novel FMD vaccine containing Dectin-1 agonist, β-D-glucan, as an immunomodulatory adjuvant. The proposed vaccine was developed to effectively coordinate innate and adaptive immunity for potent host defense against viral infection.MethodsWe demonstrated β-D-glucan mediated innate and adaptive immune responses in mice and pigs in vitro and in vivo. The expressions of pattern recognition receptors, cytokines, transcription factors, and co-stimulatory molecules were promoted via FMD vaccine containing β-D-glucan.Resultsβ-D-glucan elicited a robust cellular immune response and early, mid-, and long-term immunity. Moreover, it exhibited potent host defense by modulating host’s innate and adaptive immunity.ConclusionOur study provides a promising approach to overcoming the limitations of conventional FMD vaccines. Based on the proposed vaccine’s safety and efficacy, it represents a breakthrough among next-generation FMD vaccines

Enzymatic properties of the Caenorhabditis elegans Dna2 endonuclease/helicase and a species-specific interaction between RPA and Dna2

In both budding and fission yeasts, a null mutation of the DNA2 gene is lethal. In contrast, a null mutation of Caenorhabditis elegans dna2(+) causes a delayed lethality, allowing survival of some mutant C.elegans adults to F2 generation. In order to understand reasons for this difference in requirement of Dna2 between these organisms, we examined the enzymatic properties of the recombinant C.elegans Dna2 (CeDna2) and its interaction with replication-protein A (RPA) from various sources. Like budding yeast Dna2, CeDna2 possesses DNA-dependent ATPase, helicase and endonuclease activities. The specific activities of both ATPase and endonuclease activities of the CeDna2 were considerably higher than the yeast Dna2 (∼10- and 20-fold, respectively). CeDna2 endonuclease efficiently degraded a short 5′ single-stranded DNA tail (<10 nt) that was hardly cleaved by ScDna2. Both endonuclease and helicase activities of CeDna2 were stimulated by CeRPA, but not by human or yeast RPA, demonstrating a species-specific interaction between Dna2 and RPA. These and other enzymatic properties of CeDna2 described in this paper may shed light on the observation that C.elegans is less stringently dependent on Dna2 for its viability than Saccharomyces cerevisiae. We propose that flaps generated by DNA polymerase δ-mediated displacement DNA synthesis are mostly short in C.elegans eukaryotes, and hence less dependent on Dna2 for viability