Danny I. Cho

A survey of maintenance models for multi-unit systems

This paper surveys the literature related to optimal maintenance and replacement models for multi-unit systems. The emphasis is on work appearing since the 1976 survey A Survey of Maintenance Models: The Control and Surveillance of Deteriorating Systems by W.P. Pierskalla and J.A. Voelker. The literature is divided into five topical categories: machine interference/ repair models, group/ block/ cannibalization/ opportunistic models, inventory/ maintenance models, other maintenance/ replacement models, and inspection/ maintenance models. This paper also provides the reader with a quick guide to a variety of classification schemes. Each of the alternative classification schemes also provides an indication as to the categorization of each of the surveyed articles.

An integrated approach for supplier selection and purchasing decisions

Purpose – The paper seeks to provide academic researchers and practitioners with a better understanding about purchasing strategies through an integrated approach to supplier selection and purchasing decisions.Design/methodology/approach – This paper views supplier selection as a multi‐criteria problem. Through the analytical hierarchy process (AHP), in consideration of both quantitative and qualitative criteria, a set of candidate suppliers is identified. A multi‐objective linear programming (MOLP) model, with multiple objectives and a set of system constraints, is then formulated and solved to allocate the optimum order quantities to the candidate suppliers.Findings – The paper provides tradeoffs among different objectives, which are more consistent with the complexity and nature of the real‐world decision‐making environment. It also offers better information and solutions supporting effective purchasing decisions.Research limitations/implications – The main concept of the proposed approach can be appli...

The digital divide: global and regional ICT leaders and followers

The “digital divide” has sparked serious debates along the lines of economic disparity among world nations. Many in academics and policy circles believe that the digital gap could further widen the economic gap between developed versus developing nations. Among the components that are taken into consideration for measuring and analyzing the digital divide between countries, the information and communication technologies (ICTs) is the key component. This paper adds to the existing body of knowledge on the issue of regional and global digital divide by profiling 192 member countries of the United Nations based on their ICT indicators. Using clustering and statistical analysis, our results identify “leaders” and “followers” in ICT infrastructure and utilization at both regional and global settings. Mina Balliamoune-Lutz is the accepting Associate Editor for this article.

E-Government readiness index: A methodology and analysis

Abstract E-Government has received significant attention as digital technologies transcend private businesses and serve as a basic source of transformation in government functions. One most notable project is the United Nations Public Administration Network (UNPAN) that assesses the e-Government readiness of the 192 member nations according to a quantitative composite index involving website assessment, telecommunication infrastructure, and human resource endowment. However, the UNPAN index, though rich in depth and breadth of data collection, relies on a method that is a simple mathematical average of the values of the variables measured. This paper revisits the UNPAN index and proposes alternative indices based on principal components analysis (PCA). Using the UNPAN survey data, four different versions of the index are presented and the resulting rankings of the nations are examined vis-a-vis the existing ranking. The theoretical and policy implications of the proposed methodology and its results are discussed.

Information and Communications Technology Development and the Digital Divide: A Global and Regional Assessment

The rapid development in information and communications technologies (ICTs) has created a wealth of opportunities for businesses and societies around the world. Yet, the disparity in the ICT adoption between developed and developing countries, often referred to as the Digital Divide, continues to widen. As a result, the digital divide has remained an issue of significant importance to policy-makers and scholars. In an effort to measure the magnitude of the digital divide and monitor how the disparity evolves over time, the United Nations commissioned the development of a comprehensive ICT Development Index (IDI) in 2009. The objective of this paper is to extend the methodology used in the IDI project and other scientific results presented in previous research to measure the digital divide. Using data mining techniques, we analyze ICT profiles from 154 countries to provide a rigorous quantitative assessment of the digital divide. In addition to analyzing the digital divide at the global level, we present our results at a regional level by identifying countries that are leaders and followers in their respective geographical area. Moreover, our analysis found that between 2002 and 2007, nine countries have made a significant progress in ICT adoption such that they have transitioned into a group previously consisting primarily of developed countries.

Analysis of optimal production and advertising policies

Abstract In this paper, the joint production and advertising control model proposed by Parlar is extended to include a time dependent depreciation rate of goodwill (sales), the salvage value of inventory unsold, and the salvage value of goodwill. For an arbitrary form for the production cost function, necessary conditions for optimal production and advertising rates are obtained using the maximum principle. For specific forms (quadratic and linear) for the production cost function, optimal production and advertising policies are investigated. In addition, the solution technique used by Parlar to deal with the pure state inequality constraint is shown to be incorrect, and thus correct analyses to the problem are presented. An algorithm is developed to solve the necessary conditions and numerical examples are presented to illustrate the solution

Structural changes in the demand for wine in Canada

Purpose – The purpose of this paper is to investigate structural changes in the elasticity of demand for wine in the Province of Ontario and in Canada as a whole. It will provide academic researchers and practitioners with a better understanding about structural changes in the levels of wine demand elasticities over time. It will also help the relevant governments and wine business establishments in developing taxation policy and business decisions.Design/methodology/approach – The Kalman filter method, in conjunction with the Chow test, is applied to investigate structural changes in the elasticity of demand for wine. The Chow test is used for primary investigations of structural changes in the elasticity of demand for wine over time, whereas the Kalman filter method provides information about the behavior of the elasticity coefficients over time.Findings – The Chow test reveals that structural changes in wine demand for Ontario are more pronounced than those for Canada as a whole. The Kalman filter resu...

Investigating the Link between Beer Consumption and Economic Conditions in Canada: A Panel Data Analysis

In this paper we examine the link between beer sales, unemployment and other economic variables in Canada using provincial level panel data at monthly frequencies for the period from January 2000 to December 2010. Our panel cointegration test results indicate a stable long-run relationship between beer sales per-capita and the economic variables considered. When we account for this cointegration by specifying panel error correction models we find strong evidence that beer sales in Canada are pro-cyclical with per-capita sales increasing during good economic times as indicated by the levels of unemployment and average hourly earnings. We also find strong evidence of habit persistence in Canadian beer sales as would be expected for an addictive product. The policy implications of these results are discussed.

An objective evaluation of the Ivey Purchasing Managers Index

Purpose – The purpose of this paper is to provide academic researchers and practitioners with a better understanding of the current Ivey Purchasing Managers Index (IPMI), with alternative IPMIs, and with their appropriateness as an indicator of the performance of the Canadian economy.Design/methodology/approach – The paper makes use of principal component analysis to investigate the choice of principal variables for computing new IPMIs based on monthly data for five Ivey indexes for the period from December 2000 to May 2006. Statistical tests were made for the validity of the existing and new IPMIs using two major indicators of Canadian business and economic activities.Findings – The results suggest that a new composite purchasing managers index for Canada similar to its US counterparts be computed based on four identified Ivey indexes. For constructing a simpler and parsimonious IPMI, the results support Iveys current practice of using only one Ivey index, namely, the Purchases index.Research limitation...