Jae Young Choi

This paper extends the Roll model for implicit bid-ask spreads by incorporating the possi? bility of serial correlation in transaction type. The validity of this formula is examined using intra-day transactions and bid-ask spread data for options traded on the Chicago Board Options Exchange. The results indicate that the model derived here closely esti? mates the effective bid-ask spread in that it explains more than 80 percent of the crosssectional differences in announced bid-ask spreads.

International collaboration in research activities has been highlighted because it offers higher productivity and has a greater impact than non-international collaboration. Given the importance of international collaboration, researchers make strategic decisions on their collaboration modes in the light of their environments and the expected trade-offs, since long-distance research collaboration entails both costs and benefits. By using national data at the project level, this paper examines the

The characteristics of the smart city industry and its effects on the national economy of Korea are investigated using input-output analysis. The definition and industrial classification of a smart city are established using the Delphi technique for experts in various fields, from information and communication technologies (ICT) to governmental policies for urban matters. The results of the analysis, including the production, value added and employment induction effects, show that the smart city

Technology convergence indicates that technologies of different application areas are converted into a new and common unity of technology. Its range spans from inter-field, whereby technologies are converged between heterogeneous fields in homogeneous sector, to a wider inter-sector, whereby technologies belong to heterogeneous technology sector are converged. This paper determined the definition of technology convergence from previous literature and classified patents into technology category d

Contending that collaboration management practices and interpersonal relationships are the main factors in successful collaboration in R&D, scholars have turned their attention to the relationships between collaborators. Internal factors in research collaboration activities are not yet understood at the team level. They are the so-called black box of collaboration study. The purpose of this paper is to empirically demonstrate how factors relating to team characteristics, motivation, and processe

The impedance of the power distribution network (PDN) needs to be minimized in order to prevent unwanted voltage fluctuations at frequencies where current transients occur. To reduce PDN impedance, one can place decoupling capacitors that act as local current sources. However, selecting and placing the right capacitors at the right locations are problematic because of the complexity of modern package and board structures. In addition, decoupling capacitors are not effective at higher frequencies

Since the release of the Apple iPad and the explosion of consumer demand for tablet PCs, a number of companies are entering into the tablet PC market, creating a situation that is becoming more fiercely competitive, complex, and difficult to predict. Under the singularity of the Korean tablet PC market, into which both the iPad and Galaxy Tab (with an Android operating system) were simultaneously released, this study closely analyses consumer preferences for tablet PCs. It uses the Bayesian mixe

This paper proposes and evaluates a new aggregation algorithm in wireless sensor networks with time constraint. In the proposed algorithm, each aggregation node controls its aggregation time in order to aggregate and transfer data from child nodes within a given deadline of the sink node. The objective of the algorithm is to deliver the time constrained data within time bound while reducing the energy consumption resulted from the number of transmissions. Based on the aggregation tree, the propo