ANALYSIS ON LEXICAL DENSITY AND SOPHISTICATION IN KOREAN LEARNERS’ SPOKEN LANGUAGE

The proficiency level of second language development can be judged by the learner’s output and be used to estimate the learner’s stage of learning. The linguistic production can be used to see how a learner’s language knowledge has been internalized. In this case, factors such as accuracy, fluency, and complexity can be considered. In this study, lexical density and sophistication were analyzed in Korean learners’ spoken production as an aspect of measuring lexical complexity. The lexical density and sophistication scores were obtained from 44 students’ spoken data whose language proficiency varied from intermediate (level 3 and 4) to advanced (level 5 and 6). Also, using one-way ANOVA, statistical analysis was conducted on the differences according to the proficiency of each level. As a result, the lexical density score showed little difference according to the proficiency level, however the difference was statistically not significant. However, in the case of lexical sophistication score, the scores of advanced students were higher the intermediate students. The level of lexical sophistication corresponded with the proficiency level increased, and the differences were statistically significant

UNDERSTANDING THE IMPACT OF INSTAGRAM SPONSORED ADS: MESSAGE EXPLICITNESS AND MODERATING FACTORS ON CONSUMER PERCEPTION AND BEHAVIOR

This experimental study aims to explore how Instagram sponsored advertisements impact consumer perception and behaviors, focusing on the overarching Persuasion Knowledge Model (PKM) theory. The study consists of two distinct experiments, each examining different moderators while maintaining a central emphasis on message explicitness and its interaction with other variables. In Study 1, participants were exposed to Instagram sponsored ads featuring different levels of message explicitness (explicit vs. implicit) and varying product types (utilitarian vs. hedonic). The main outcome variable assessed was immediate purchase intent. The mediators, persuasion knowledge, and perceived deceptiveness, were also analyzed to understand their impact on the correlation between message explicitness, product type, and purchase intent. The results supported the impact of perceived deceptiveness on immediate purchase intent. In Study 2, the focus remained on message explicitness (explicit vs. implicit), but the moderator shifted to ad skepticism, a continuous variable. Like the first study, the analysis included mediation by persuasion knowledge and perceived deceptiveness. The findings revealed a noteworthy difference between explicit and implicit messages concerning perceived deceptiveness. Both studies employed random participant assignment to distinct experimental conditions to ensure unbiased outcomes. Data collection occurred through online surveys, and a total of 298 participants took part in the study. The discoveries from this dissertation furnish valuable insights into the efficacy of Instagram sponsored ads and illuminate the significance of message explicitness and moderating factors in shaping consumer perceptions and behaviors. The findings of the study enhance our understanding of PKM in the realm of social media sponsored advertising, providing meaningful guidance to marketers and advertisers in crafting more impactful and targeted ad campaigns across Instagram and other social platforms. Ultimately, this research aids in advancing knowledge within the realm of sponsored advertising on social media and its impact on consumer behavior

Essays on corporate finance and product market competition

textThis dissertation contains two essays on the aggressive behavior of corporations in product market competition. In the first essay, I investigate how market structure can impact a firm's risk of facing predation by rivals, and hence, its financial policy decisions. Using a simple model, I demonstrate that a firm faces a greater predation threat when it meets the same competitor in many markets, as this competitor is able to internalize more of the benefit, degrading the firm's ability to compete in the future through aggressive actions today. I then test the predictions of the model using 2003-2011 panel data on store location across retail store chains in the US. I find that firms tend to expand more aggressively in markets shared with a competitor experiencing a substantial increase in leverage, or a decline in a credit rating, when they face that competitor in more of the other markets. The expansion relationship was found to be stronger in data from the 2008-2009 financial crisis, a period when difficulty in rolling over or obtaining new debt made it especially hard for weak firms to absorb losses. I also show that a firm facing the same competitors in many markets choose lower levels of leverage and that it decreases that leverage when a merger in the industry increases the amount of competitive overlap it has with other firms. These results suggest that firms are aware of the predation risk due to a competitive overlap and select financial policies to minimize this risk. In the second essay, I study the impact of internally generated funds on product market competition. More specifically, I investigate the idea that firms compete aggressively when their competitors face cash flow shortfalls. Testing this idea is challenging because competitor's cash flow changes are potentially endogenous with respect to firm's behavior. I address this problem in three ways. First, I investigate firm's reaction in a given market when its competitors face cash flow shortfalls outside of that market; this analysis is conducted using store location data on retail store chains. Second, I focus on the 2008-2009 financial crisis period in which retail store chains were hit by a negative demand shock which was hardly expected ex ante. Finally, I use a shock to local economic conditions which varies across markets and the different distributions of store locations across firms as instruments for the changes in competitors' cash flows. I find that a firm expands more in a given market in which it competes with rivals which face a more negative cash flow shortfall in the other markets. This relation is stronger when the competitors were highly leveraged before the crisis. Finally, I illustrate evidence that a firm responds more aggressively to competitor's cash flow shortfalls if it competes with that competitor in many of the same markets; this result is consistent with the prediction of the model in Chapter 1. These essays contribute to the literature by adding new evidence on the predatory behavior of corporations in product market competition.Financ

Contribution of the family environment to depression in Korean adults with epilepsy

AbstractPurposeDepression is common in adults with epilepsy and an important factor that affects quality of life in these individuals. However, there are few studies on the interactions between epilepsy and family factors in adults and we here investigate this association.MethodsThis cross-sectional, multicenter study collected data on 391 adults with epilepsy and their caregivers recruited from 27 hospitals throughout Korea. The Beck Depression Inventory (BDI), Stigma Scale, and Caregiver Burden Inventory (CBI) were used to evaluate the study population. Multivariate analysis was conducted using hierarchical linear regression. The Sobel test and structural equation modeling were used to examine interrelationships among the potential factors.ResultsThe mean patient BDI score was 16.3 (SD=11.1). Depressive symptoms (BDI≥10) were in 68.3% and 57.0% in patients and their caregivers, respectively. Hierarchical linear regression analysis only identified caregiver BDI (β=0.219; p<0.001) as an independent factor related to patient BDI. The mediational model suggested that caregiver BDI mediated the effects of other family factors on patient BDI: caregiver's educational level (p=0.002), caregiver's CBI score (p<0.001), caregiver's Stigma Scale score (p<0.001), and family APGAR score (p<0.001). In addition, structural equation modeling showed that the relation between caregiver and patient BDI was unidirectional.ConclusionCaregiver depression is the most important contributor to depression in adults with epilepsy. The other family factors such as caregiver's perception of burden and the level of family function are indirectly correlated with patient depression via the mediating effects of caregiver depression

A Model for Sustainable Courier Services: Vehicle Routing with Exclusive Lanes

In Southeast Asian cities, it is common for logistic companies to operate a heterogeneous fleet of delivery vehicles with motorcycles being the preferred vehicle to handle the final phase of delivery. In such scenarios, heterogeneous fleet vehicle routing problem (HFVRP) is generally applied to plan an optimal delivery. However, in many downtown cores of large and rapidly developing Southeast Asian cities, HFVRP is neither viable nor reliable because of road usage restrictions. The purpose of this article is to develop and test a different approach that accurately takes these restrictions into account and provides viable and more sustainable results. Restrictions in this paper refer to situations of urban areas in Vietnam where (i) certain vehicle types are prohibited in specified areas or where narrow alleyways limit the utilization of vehicles that exceed the road capacity and (ii) certain roads are exclusive to certain vehicle types. In networks, limited access and exclusive lanes are represented as links, or arcs, exclusive to one or another. Taking these limitations into consideration, we have developed a unique model, which we have termed Vehicle Routing Problem with Exclusive Links (VRP-EL). The model was validated and tested for its performance on scenarios with varying ratios of exclusive links. Scenarios up to 500 customers were tested on a meta-heuristic algorithm, simulated annealing. VRP-EL produces realistic outcomes. Limiting certain links to be selected according to vehicle types increases overall travel distance. However, this increase outweighs the cost of re-planning and rerouting had they not been constrained initially. The reduction in traveling distance leads to fossil fuel reduction for the overall system. The estimation of reduced carbon emissions through applying the proposed model is presented. Considering the severe traffic congestion and carbon emissions caused by motorcycles in Vietnam, the proposed model leads to a sustainable road environment. Document type: Articl

CD4+ T cells from MHC II-dependent thymocyte–thymocyte interaction provide efficient help for B cells

Recently, a novel CD4+ T-cell developmental pathway was reported that generates thymocyte–thymocyte (T–T) CD4+ T cells. We established a mouse system (CIITAtgCIITApIV−/−) where thymic positive selection occurred only by major histocompatibility complex (MHC) class II+ thymocytes. T–T CD4+ T cells selected via MHC class II-dependent T–T interaction are comprised of PLZF-negative and innate PLZF-positive populations. Until recently, the functional role of the PLZF-negative population was unclear. In this study, we demonstrate that naïve T–T CD4+ T cells provide B-cell help to a level comparable with that of naïve conventional CD4+ T cells. Considering the absence of PLZF expression in naïve T–T CD4+ T cells, these results suggest that PLZF-negative naïve T–T CD4+ T cells are functionally equivalent to conventional naïve CD4+ T cells in terms of B-cell help

Gravitational-wave Electromagnetic Counterpart Korean Observatory (GECKO): GECKO Follow-up Observation of GW190425

One of the keys to the success of multimessenger astronomy is the rapid identification of the electromagnetic wave counterpart, kilonova (KN), of the gravitational-wave (GW) event. Despite its importance, it is hard to find a KN associated with a GW event, due to a poorly constrained GW localization map and numerous signals that could be confused as a KN. Here, we present the Gravitational-wave Electromagnetic wave Counterpart Korean Observatory (GECKO) project, the GECKO observation of GW190425, and prospects of GECKO in the fourth observing run (O4) of the GW detectors. We outline our follow-up observation strategies during O3. In particular, we describe our galaxy-targeted observation criteria that prioritize based on galaxy properties. Armed with this strategy, we performed an optical and/or near-infrared follow-up observation of GW190425, the first binary neutron star merger event during the O3 run. Despite a vast localization area of 7460 deg^2, we observed 621 host galaxy candidates, corresponding to 29.5% of the scores we assigned, with most of them observed within the first 3 days of the GW event. Ten transients were discovered during this search, including a new transient with a host galaxy. No plausible KN was found, but we were still able to constrain the properties of potential KNe using upper limits. The GECKO observation demonstrates that GECKO can possibly uncover a GW170817-like KN at a distance less than 200 Mpc if the localization area is of the order of hundreds of square degrees, providing a bright prospect for the identification of GW electromagnetic wave counterparts during the O4 run.Comment: 35 pages, 19 figures Accepted for publication in Ap