Information Quality for Mobile Internet Services: A Theoretical Model with Empirical Validation

Providing customers with high quality of information is a key determinant for the success of the mobile Internet. This study aims at identifying the important dimensions of information quality in increasing user satisfaction and customer loyalty for mobile Internet services. In order to achieve this goal, we propose a general model of information quality with four dimensions. The dimensions were constructed by expanding prior research in information quality in order to reflect the characteristics of the mobile Internet. We hypothesize that the four dimensions are positively related to user satisfaction and customer loyalty, and that their relative importance varies according to user goals. To validate the hypothesized model, we conducted a large-scale Internet survey with mobile Internet users. The results indicate that some dimensions are more important than others in increasing user satisfaction and loyalty, and relative importance of the dimensions varies according to the intended goals of mobile Internet contents

Essays on Childhood Environments and Human Capital Formation

This thesis comprises three papers that examine childhood environment effects on individual cognitive and health outcomes in adulthood. Chapter 2 examines the relationship between fertility and the gender gap in cognitive skills in a society where son preference is prevalent. Drawing on Becker's Quantity-Quality trade-off model, I empirically test if the trade-off between quantity and quality of children is larger for daughters than that for sons. To consider the endogenous nature of the demand for children, I exploit an exogenous variation in fertility due to China's family planning policy. We utilise the policy intensity information collected from hundreds of county gazetteers as an instrument for family size. The main results suggest that an additional sibling widens the gender gap in cognitive test scores by 33.2% of a standard deviation in the rural sample and 9.8% in the urban sample. The pattern is more pronounced in regions with a higher proportion of people who prefer a son over a daughter, and among households who face tighter budget constraints. I also provide suggestive evidence that our findings are strongly associated with belief in a son's role to carry on family lineage in Confucian tradition. Chapter 3 explores childhood environment effects on adult height. Between 1950 to 1990, Chinese average adult height increased more than 1 cm a decade. This is an impressive achievement. This paper describes the trend of adult height growth during this period and explores the reasons behind such a trend. The result suggests that during the 40-year period, the growth of adult height increased, with the most substantial increase occurring in the last decade. One important reason behind the increase in adult height is the continued increase in government per capita spending on health and education throughout the forty-year period. However, the recent impressive growth was mainly due to the market-oriented economic reforms introduced in the 1980s. The observed height growth in the 1980s is a combination of two opposing factors, economic reforms and the introduction of the One Child Policy (OCP). We find that once we control for the 'number of siblings' after the introduction of the OCP, the revealed economic reform effects become much larger. The effect of OCP is, in general, negative on height and, in particular, for rural females owing to the widespread son-preference in the rural society. Chapter 4 tests whether long-term exposure to single-sex schooling is beneficial for female cognitive performance. While recent studies have demonstrated that single-sex schooling improves girls' academic performance, little evidence is available as to how long it can be effective. By exploiting South Korea's random school assignment policy, we attempt to answer this question. The results suggest that attending single-sex schools improves female academic performance for the first three years of exposure, consistent with existing evidence. However, girls exposed to single-sex education for their entire secondary school life perform worse than girls with less exposure at the college entrance exam. The estimates are robust to the inclusion of controls of individual, parental, and school characteristics. These patterns are not clear among boys. We provide suggestive evidence that show a gender-salient environment in single-sex schools may drive the results

Monarch Butterfly Optimization for Facility Layout Design Based on a Single Loop Material Handling Path

Facility layout problems (FLPs) are concerned with the non-overlapping arrangement of facilities. The objective of many FLP-based studies is to minimize the total material handling cost between facilities, which are considered as rectangular blocks of given space. However, it is important to integrate a layout design associated with continual material flow when the system uses circulating material handling equipment. The present study proposes approaches to solve the layout design and shortest single loop material handling path. Monarch butterfly optimization (MBO), a recently-announced meta-heuristic algorithm, is applied to determine the layout configuration. A loop construction method is proposed to construct a single loop material handling path for the given layout in every MBO iteration. A slicing tree structure (STS) is used to represent the layout configuration in solution form. A total of 11 instances are tested to evaluate the algorithm’s performance. The proposed approach generates solutions as intended within a reasonable amount of time

Environmental Monitoring and Risk Assessment of Pharmaceutical Residues Discharged from Large Livestock Complex in the Geum River Basin, South Korea

This study aims to collect water samples from two tributaries within the Geum River basin in South Korea, where large-scale livestock complexes are located, to quantify the measured environmental concentration (MEC) of pharmaceutical residues using a multiresidue analytical method developed with liquid chromatography–tandem mass spectrometry (LC-MS/MS), and to evaluate the environmental risks posed by the detected pharmaceuticals to aquatic organisms. The water samples were collected at a total of 17 points, including up-, middle-, and downstream of the Seoksong and Nonsan-Gangkyoung streams connected to the Geum River, from October 2018 to March 2019. A multiresidue analytical method using LC-MS/MS was developed to quantify 49 pharmaceuticals with hydrophilic lipophilic balance using solid phase extraction. The recovery rates varied between 67.23% and 136.98%, while the limits of quantification were from 3.99 to 46.32 ng/L. Ecotoxicological information on acute and chronic effect endpoints (e.g., EC50, NOEC, etc.) was obtained from the U.S. EPA ECOTOX Knowledgebase. Considering the worst-case scenario, the lowest observed effect endpoint (mainly NOEC) of the most sensitive species was selected, and predicted no effect concentration (PNEC) values were calculated by dividing the endpoint by an assessment factor (AF). The mean, minimum, and maximum MECs of pharmaceuticals were divided by PNECs to calculate risk quotient (RQ). Caffeine was detected in all sampling sites with a detection frequency of 100%. High levels of pharmaceuticals (9.212 μg/L of sulfathiazole, 8.479 μg/L of acetaminophen, and 5.885 μg/L of florfenicol) were detected. The RQ values exceeded 1 and reached up to 84.79 (high risk category) for acetaminophen, and were between 0.11 and 0.83 (moderate risk) for carbamazepine, etc. The RQs for the rest of the 15 substances were below 1 (low risk). In the future, further studies should be conducted to monitor other micropollutants, including industrial chemicals, pesticides, etc., at different locations of the Geum River basin, including livestock farms, pharmaceutical manufacturing facilities, wastewater treatment plants, and other facilities, for long-term period

Explaining trends in adult height in China: 1950 to 1990

This paper explores the changing trend of adult height in China for cohorts born in 1950–90. We use information on household structure and local economic conditions during the individual’s childhood to explain the trend. We find that during the 40-year period, the growth rate of adult height increased, with the most substantial increase occurring in the 1980s. One important contributing factor to the growth of adult height is the continued increase in government per capita spending on health and education. The impressive growth in the 1980s was mainly due to the introduction of market-oriented economic reforms, rather than the advent of the One-Child Policy. We find that the positive effect of economic reforms was larger for urban dwellers than for their rural counterparts and within the rural areas the benefit was far greater for men than for women