Sung-Min Jeon

This study examines the dynamics of the digital divide between middle- and low-income groups of 44 African countries in the context of three technologies – mobile cellular, Internet, and fixed broadband – from 2000 to 2015. At the macro level, the relative digital divide has been narrowing at the annual rates from 11.3% to 0.72%, while the absolute digital divide has been widening at the annual rates from 31.33% to 17.11%. At the microlevel, convergence analysis indicates that a catch-up process

Shortly after Groupon started its business in 2008, selling one deal a day with substantial price discounts, daily-deal sites became new online shopping places for many people. Starting with Groupon, most daily-deal sites required that voucher sales be higher than a predetermined number before deals become active. This feature, known as the “tipping point,” was a unique characteristic of the daily-deal business and is identified as one of the most prominent features of social shopping. Most dail

With the recent acceleration in AI adoption and significant investments being made by many countries, the concern regarding the AI divide is becoming increasingly prevalent. We attempt to determine whether countries that have fallen behind in AI development can catch up to those leading the charge over time. Specifically, this study examines the dynamics of the AI divide on AI investments, robotics, AI start-ups, and AI patents in 34–57 countries, analyzing the data sets from Stanford AI Index R

Projections of long-term carbon dioxide (CO2) emissions in the literature vary over a wide range depending on both socio-economic development and mitigation policy. Therefore, any attempt to improve the accuracy of such projections is important. We present a simple aggregate model to project the future carbon intensity of economic output, which is then used to forecast energy-related CO2 emissions through 2040 for seven countries and three regions of the world. Our projection results are compare

A notion of almost minimizers is introduced for certain variational problems governed by the fractional Laplacian, with the help of the Caffarelli–Silvestre extension. In particular, almost fractional harmonic functions and almost minimizers for the fractional obstacle problem with zero obstacle are treated. It is shown that for a certain range of parameters, almost minimizers are almost Lipschitz or <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/Mat

In this paper we introduce a notion of almost minimizers for certain variational problems governed by the fractional Laplacian, with the help of the Caffarelli-Silvestre extension. In particular, we study almost fractional harmonic functions and almost minimizers for the fractional obstacle problem with zero obstacle. We show that for a certain range of parameters, almost minimizers are almost Lipschitz or $C^{1,β}$-regular.

We consider Anzellotti-type almost minimizers for the thin obstacle (or Signorini) problem with zero thin obstacle and establish their $C^{1,β}$ regularity on the either side of the thin manifold, the optimal growth away from the free boundary, the $C^{1,γ}$ regularity of the regular part of the free boundary, as well as a structural theorem for the singular set. The analysis of the free boundary is based on a successful adaptation of energy methods such as a one-parameter family of Weiss-type m

We study almost minimizers for the thin obstacle problem with variable Hölder continuous coefficients and zero thin obstacle, and establish their C^{1,\beta} regularity on the either side of the thin space. Under an additional assumption of quasisymmetry, we establish the optimal growth of almost minimizers as well as the regularity of the regular set and a structural theorem on the singular set. The proofs are based on the generalization of Weiss- and Almgren-type monotonicity formulas for almo