Network Marketing on a Small-World Network

We investigate a dynamic model of network marketing in a small-world network structure artificially constructed similarly to the Watts-Strogatz network model. Different from the traditional marketing, consumers can also play the role of the manufacturer's selling agents in network marketing, which is stimulated by the referral fee the manufacturer offers. As the wiring probability $\alpha$ is increased from zero to unity, the network changes from the one-dimensional regular directed network to the star network where all but one player are connected to one consumer. The price $p$ of the product and the referral fee $r$ are used as free parameters to maximize the profit of the manufacturer. It is observed that at $\alpha=0$ the maximized profit is constant independent of the network size $N$ while at $\alpha \neq 0$, it increases linearly with $N$. This is in parallel to the small-world transition. It is also revealed that while the optimal value of $p$ stays at an almost constant level in a broad range of $\alpha$, that of $r$ is sensitive to a change in the network structure. The consumer surplus is also studied and discussed.Comment: 12 pages, to appear in Physica

Experimental Study on the Subcooled Boiling Flow via Optical Measurement Techniques

A series of experimental work to investigate the subcooled boiling flow in a vertical square upward flow channel is described. As experimental methods, high-speed photography and infrared (IR) thermometry were employed simultaneously. The research scope explored includes (i) measurement issues of fundamental bubble parameters through visualization, (ii) experimental methodology to achieve both enhanced two-phase flow visualization and accurate wall temperature measurement, and (iii) measurement of diverse aspects of bubble dynamics as well as wall heat transfer by applying the verified experimental approach. Before producing the actual data, substantial effort was first made to identify the critical measurement issues of fundamental bubble parameters in a forced convective boiling system. Those issues have never been explicitly addressed in previous studies despite the possibly critical impacts on the experimental results. Thus, a series of systematic experimental investigations was performed to uncover those issues and to verify the errors created by not addressing them, based on which more suitable ways of observing and characterizing such parameters through experiments were discussed. Then, an experimental strategy to achieve high-fidelity optical measurements using both high-speed photography and IR thermometry was established. To attain the goal, the important issues such as test section design, IR thermal imaging issues, visualization strategy, wall temperature tracking method, and experimental validations were extensively addressed. Also, the feasibility of current experimental approach was demonstrated through the subcooled flow boiling experiment. Finally, by employing the experimental strategy established, an experimental investigation of the subcooled boiling flow was conducted. The experiment was performed in a vertical square upward flow channel using refrigerant NovecTM 7000, in which a single nucleation site was purposely activated for a fundamental study of subcooled flow boiling process. The various aspects of bubble behavior under different subcooled flow boiling conditions were examined using both micro- and macroscopic views of high-speed cameras while measuring the wall temperature/heat flux with IR thermometry. Additionally, based on the measurements of various bubble parameters as well as wall heat transfer, relevant relations among those parameters and the underlying mechanisms were intensively discussed

The Fiscal Burden of Korean Reunification: A Generational Accounting Approach

This paper uses Generational Accounting to assess the fiscal impacts of Korean reunification. Our findings suggest that early reunification will result in a large increase in the fiscal burden for most current and future generations of South Koreans. The Korean reunification's fiscal impact appears much larger than that of German reunification, due to a wider gap in productivity between the two Koreas and North Korea's much larger share of the unified country's population. The projected large-scale fiscal burden on South Korea is attributable primarily to the rapid increase in social welfare expenditure for North Korean residents, rather than to the direct reconstruction cost of the North Korean economic system after the disintegration of its old economic regime.

Non-financial hurdles for human capital accumulation : landownership in Korea under Japanese rule

This paper suggests that inequality in landownership is a nonfinancial hurdle for human capital accumulation. It is the first to present evidence that inequality in landownership had an adverse effect on the level of public education in the Korean colonial period. Using a fixed effects model, the present research exploits variations in inequality in land concentration across regions in Korea and accounts for the unobserved heterogeneity across these regions. The analysis establishes a highly significant adverse effect of Land inequality on education in the Korean colonial period

A neo-Schumpeterian perspective on the analytical macroeconomic framework : the expanded reproduction system

This study aims to introduce a new analytical macroeconomic framework, the expanded reproduction system, that combines the accumulated wisdom of several contemporary economic models while also compensating for their shortcomings. This new framework may be used to study macroeconomic phenomena from both the supply and demand side over a number of different time intervals. Furthermore, as we account for both new product and productivity innovations, we are able to account for both qualitative and quantitative developments within the economy

Clinical analysis of pediatric patients who visited Masan Samsung Emergency Center

Purpose : Through a clinical and retrospective analysis of pediatric patients who visited the Regional Emergency Medical Center of Masan Samsung Hospital from January 2007 to December 2008, we characterized pediatric and adolescent emergency patients to improve emergency care in future. Methods : We reviewed the medical records of 14,065 pediatric patients below 19 years of age. Results : The male to female ratio was 1.5:1, and the most common age group was less than 3 years (49.6%). The peak month was May (10.0%), the peak day of the week was Sunday (24.7%), and the peak time of day was 20:00&amp&#59;#8211&#59;20:59 (8.5%). There was no difference in the number of visits per day based on weather (sunny, rain [below 10 mm per day], snow, and fog) or daily temperature difference&#59; however, visits increased on sandy, dusty days and decreased on rainy days with more than 10 mm of rain per day. Based on the international classification of disease (ICD)-10 system, the most common disease code was code R (symptoms, sign, and abnormal clinical laboratory finding) (31.5%), and the most common symptom was fever (13.1%). Final outcomes were discharged (73.8%), admitted (25.7%), transferred (0.4%), and expired (0.1%). In adolescent patients aged 15&amp&#59;#8211&#59;19 years, the most common disease code was Injury &amp&#59; Poisoning (code S&amp&#59;T, 36.9%)&#59; the most common symptom was abdominal pain (9.6%). Conclusion : Pediatric patients visiting the emergency center were most likely to be male and under 3 years of age and to visit between 20:00 and 21:00 on Sundays and in May, and the most common symptom was fever. Differences between adolescents and pediatric patients showed that adolescents had a higher visiting rate with abdominal pain and a larger temperature difference