Youngsun Kwon

The Value Drivers of US Internet Retailers

This study empirically explores the role of web traffic in explaining the stock prices of e-tailers. In particular, we hypothesize that the actual buy rate is a key value driver of Internet retailers because it represents the direct performance of these firms in the electronic market place. Our empirical analysis indicates that the buy rate is strongly related to the market value of e-tailers in a positive way after controlling for the roles of such financial valuation measures as net income, revenue, sales and marketing expenses, research and development costs, and book value.

Differences between LTE and 3G service customers

This paper assesses the differences between 3G and LTE subscribers.The validity of the traditional determinants of customer satisfaction is tested.The effects of customer satisfaction and switching costs on loyalty are analyzed.This study finds that LTE users care more about data service quality than 3G users. South Korea has now become one of the worlds leading mobile service markets with the launch of its advanced LTE services; the LTE service subscription rate in Korea has exceeded 50% as of November 2013. This development raises the question of how LTE service subscribers may differ from 3G service subscribers. Within the context of this rapidly changing environment of mobile service markets, this study examines the validity of the traditional determinants of customer satisfaction in data-service oriented mobile communications markets, analyzes the effects of customer satisfaction and switching costs on customer loyalty, and assesses the difference between 3G and LTE subscribers with respect to their determinants of customer loyalty. The results show that there are significant differences between 3G and LTE subscribers while traditional factors such as call quality, data quality, customer support, and price perception are still significant determinants of customer satisfaction.

S&T knowledge production from 2000 to 2009 in two periphery countries: Brazil and South Korea

This paper investigates the dynamic evolution profiles of science and technology knowledge production in Brazil and the Republic of Korea from 2000 to 2009. The two countries have followed different models of publication profiles, bioenvironmental model and Japanese model, and they currently belong to periphery countries in terms of the center-periphery framework. Brazil and the Republic of Korea have established a few core disciplines successfully and increased their share in the world publication of scientific papers over the last decade. Notwithstanding the fact that the two countries have recorded sustained growth in the percentage of published scientific papers, South Korea has evolved into a more balanced science and technology knowledge production system, whereas Brazil into the more unbalanced knowledge production system. Core-lagging or periphery-lagging patterns of science production have been revealed in Brazil and indirectly imply that the existing science base has not been fully stimulated or utilized.

Super ray based updates for occupancy maps

We present a novel approach, Super Ray, for efficiently updating map representations such as grids and octrees with point clouds. In this paper, we define a super ray for points as a representative ray to them with an associated frustum. A super ray is constructed in a way that updating those points has the same set of cells accessed during the map update process. As a result, we can perform the update process with a super ray in a single traversal on the map, resulting in performance improvement without compromising any representation accuracy of the map. For constructing super rays efficiently, we propose mapping lines for handling 2-D and 3-D cases from an observation that edges or grid points branch out the access pattern of updating the map. Our method is general enough to be applied for variety of occupancy map structures based on axis-aligned space subdivisions such as grids and octrees. We test our method into indoor and outdoor benchmarks, and achieve 2.5 times on average (up to 3.5 times) performance improvement over the state-of-the-art update method for OctoMap and grid maps.