The Influence of Sense of School Community on Korean Students’ Life Satisfaction and Comparison of Sense of Community for Students’ Gender and High School Specialties

The purpose of this study was to compare the sense of community of South Korean high school students as measured by a Korean version of the Sense of Community Index 2 (KSCI2) and examine the effect of two factors of the KSCI2, reinforcement of needs and influence, on students’ life satisfaction as measured by the Satisfaction with Life Scale (SWLS). A total of 375 Korean high school students provided usable data from three vocational high schools specializing in agriculture, electronics and engineering, and business and marketing, and one Meister high school specializing in automotive. Descriptive statistics, independent t-test, one-way ANOVA, and path analysis with structural equation modeling (SEM), were performed to analyze data. Findings suggested that there were statistically significant differences in reinforcement of needs, influence, and life satisfaction, for the gender of students and school specialties. First, male students scored higher than female students on reinforcement of needs and influence. Next, male students were more satisfied with their lives than female students. For reinforcement of needs, students specializing in automotive scored higher than those specializing in business and marketing. For influence, students specializing in automotive scored higher than those specializing in all the other three specialties. Finally, both factors of reinforcement of needs and influence had positive effects on students’ life satisfaction. Implications and suggestions for further studies are discussed

Essays on Energy Efficiency and Pricing Behavior in the U.S. Automobile Market: Evidence from Hybrid Electric Vehicles

This dissertation consists of three essays on the energy efficiency and pricing behavior of firms in the U.S. automobile market with a focus on Hybrid Electric Vehicles (HEVs). The first essay analyzes the market share of HEVs and evaluates consumers\u27 willingness to pay (WTP) for future fuel cost savings by purchasing fuel efficient HEVs. Estimates of consumers\u27 WTP for future fuel cost savings and the finding of an implicit discount rate of 8.35%~14.35% suggest that consumers undervalue future fuel cost savings from purchasing HEVs, and that consumers want a return on their investment on fuel cost saving HEV technology in 7~11 years. The second essay empirically investigates the existence of quality-based price discrimination in the U.S. automobile market. By estimating a structural model of demand and supply in the automobile market, I can recover marginal costs, markups and percentage markups for all vehicle models sold between 2000 and 2013. The extent of price discrimination is then examined by comparing markup and percentage markup differences between HEVs and gasoline vehicles. The results demonstrate that automobile manufactures charge both higher markups and higher percentage markups on their HEV models. On average, HEVs have higher markups by 11.1% compared to gasoline vehicles, and Toyota, a leader in the HEV market, charges higher markups on their HEV models compared to other manufacturers. The Toyota Prius, the top-selling hybrid car in the U.S. market, particularly enjoys a higher markup and percentage markup than other competitive vehicles. The third essay provides a model of the automobile market where consumers have heterogeneous preferences, caring about both the environment and the physical quality of the product—specifically its fuel economy. Many of the results found by the model are to be expected: consumers buy fewer vehicles when the environmental damages (emissions) and prices of vehicles increase; more vehicles are sold when vehicles are equipped with better fuel technology; and consumers buy fewer vehicles as they become more pro-environmental. One unexpected finding stands out: a tax on gasoline vehicles always decreases total emissions, while a subsidy for environmentally friendly HEV adoption may not

Muscular Activity Patterns in 1-Legged vs. 2-Legged Pedaling

Background: One-legged pedaling is of interest to elite cyclists and clinicians. However, muscular usage in 1-legged vs. 2-legged pedaling is not fully understood. Thus, the study was aimed to examine changes in leg muscle activation patterns between 2-legged and 1-legged pedaling. Methods: Fifteen healthy young recreational cyclists performed both 1-legged and 2-legged pedaling trials at about 30 Watt per leg. Surface electromyography electrodes were placed on 10 major muscles of the left leg. Linear envelope electromyography data were integrated to quantify muscle activities for each crank cycle quadrant to evaluate muscle activation changes. Results: Overall, the prescribed constant power requirements led to reduced downstroke crank torque and extension-related muscle activities (vastus lateralis, vastus medialis, and soleus) in 1-legged pedaling. Flexion-related muscle activities (biceps femoris long head, semitendinosus, lateral gastrocnemius, medial gastrocnemius, tensor fasciae latae, and tibialis anterior) in the upstroke phase increased to compensate for the absence of contralateral leg crank torque. During the upstroke, simultaneous increases were seen in the hamstrings and uni-articular knee extensors, and in the ankle plantarflexors and dorsiflexors. At the top of the crank cycle, greater hip flexor activity stabilized the pelvis. Conclusion: The observed changes in muscle activities are due to a variety of changes in mechanical aspects of the pedaling motion when pedaling with only 1 leg, including altered crank torque patterns without the contralateral leg, reduced pelvis stability, and increased knee and ankle stiffness during the upstroke

A Linear Time Algorithm for Constructing Hierarchical Overlap Graphs

The hierarchical overlap graph (HOG) is a graph that encodes overlaps from a given set P of n strings, as the overlap graph does. A best known algorithm constructs HOG in O(||P|| log n) time and O(||P||) space, where ||P|| is the sum of lengths of the strings in P. In this paper we present a new algorithm to construct HOG in O(||P||) time and space. Hence, the construction time and space of HOG are better than those of the overlap graph, which are O(||P|| + n^2).Comment: 8 pages, 2 figures, submitted to CPM 202

Trends and educational variation in the association between spouses' marital histories in South Korea, 1993-2017

Background: Marriages between divorced and never-married individuals indicate a society's openness to divorce and have implications for children's well-being. Few studies have examined the association between spouses' marital histories, its educational variation, and the trends therein outside of the United States. Objective: Little is known about trends in assortative mating by marital history in more traditional societies, where stigma against divorce often remains. This study examined the changing patterns of assortative mating by marital history in South Korea across 25 single-year marriage cohorts, 1993-2017. Methods: Calculating the odds ratios from two-by-two marriage tables classifying spouses' marital histories and also applying individual-level logistic regression models to 7,451,399 marriages formed from 1993 to 2017, we investigated trends in the association between spouses' marital histories. We further explored heterogeneity in the strength of the association between spouses' marital histories and its trends over time by spouses' educational combinations. Results: The association between spouses' marital histories has declined over time across all educational groups. However, crossing boundaries of marital history is most difficult in marriages where the man and woman are both college-educated and is easiest in marriages where the man and woman are both non-college-educated. Contribution: We document the trends in marital history homogamy (which has not received much attention in the literature) in Korea, with distinctive contexts of divorce and remarriage. Presenting educational patterns in the association between spouses' marital histories is another contribution

Investigating Influence of Hydrological Regime on Organic Matters Characteristic in a Korean Watershed

Source tracking of dissolved organic matter (DOM) is important to manage water quality in rivers. However, it is difficult to find the source of this DOM because various DOMs can be added from the river watershed. Moreover, the DOM composition can be changed due to environmental conditions. This study investigated the change of organic matter characteristics in the Taewha River of Ulsan City, Korea, before and after rainfall. A Soil and Water Assessment Tool (SWAT) was used to simulate water flow from various sources, and dissolved organic matter characterization was conducted in terms of molecular size distribution, hydrophobicity, fluorescence excitation and emission, and molecular composition. From the results, it was found that lateral flow transported hydrophobic and large-molecule organic matter after rainfall. According to the orbitrap mass spectrometer analysis, the major molecular compound of the DOM was lignin. Coupling the SWAT model with organic matter characterization was an effective approach to find sources of DOM in river

Preparation of a Microporous Polyurethane Film with Negative Surface Charge for siRNA Delivery via Stent

Polyurethane (PU) and polyethylene glycol (PEG) were used to prepare a porous stent-covering material for the controlled delivery of small interfering RNA (siRNA). Microporous polymer films were prepared using a blend of polyurethane and water-soluble polyethylene glycol by the solution casting method; the PEG component was extracted in water to make the film microporous. This film was dipped in 2% poly(methyl methacrylate-co-methacrylic acid) solution to coat the polymer film with the anionic polyelectrolyte. The chemical components of the film surface were characterized by Fourier Transform Infrared (FTIR) spectroscopy and its structural morphology was examined by scanning electron microscopy (SEM). The effect of the negatively charged surface after attachment of a fluorescein isothiocyanate- (FITC-) labeled siRNA-polyethyleneimine complex onto the microporous polyurethane film and the controlled release of the complex from the film was investigated by fluorescence microscopy. Fluorescence microscopy showed the PU surface with intense fluorescence by the aggregates of the FITC-labeled-siRNA-PEI complex (measuring up to few microns in size); additionally, the negatively charged PU surface revealed broad and diffuse fluorescence. These results suggest that the construction of negatively charged microporous polyurethane films is feasible and could be applied for enhancing the efficiency of siRNA delivery via a stent-covering polyurethane film

A Novel Function Complexity-Based Code Migration Policy for Reducing Power Consumption

Embedded system designs have changed greatly owing to rapid developments in both hardware and software technology. Typical design should consider hardware limitations, such as size, weight, or battery capacity. In other words, the designs are heavily dependent on the hardware component. Since hardware can deteriorate and degenerate, hardware-aware software design is needed to achieve power-efficient embedded systems. Studies usually focus on the microprocessor in terms of optimizing power consumption. Besides computation, however, the system also consumes power when executing programs. A lot of memory accesses result in the entire execution, it should be considered to minimize for more efficient designs. Modern embedded systems often use heterogeneous memory to benefit from different characteristics of memory devices. This study aims to optimize the power efficiency of heterogeneous memory in embedded systems. We have proposed a detailed function complexity concept to identify specific function units in a program that consume less power in migrated memory. Using the function complexity, function selection algorithm is proposed to select a unique function which improves most after the migration. Experiments and quantitative analyses with various benchmarks have been performed to prove the validity of the proposed algorithm. Power consumption is successfully minimized by migrating certain function of a program in low-power memory