Byeong-Yun Chang

Quality factor analysis of metalworking process with AHP

Many manufacturing processes have various factors that affect the quality of the products, and the analysis and optimisation of these factors are critical activities for engineers. Although much research has been done on statistical methods to investigate the effects of these factors on quality metrics, these statistical methods are not always applied in real-world situations because of problems involving data integrity, lack of control/measurement, or technical/administrative constraints. On the other hand, conventional heuristic methods for the selection of critical quality factors are mostly devoid of metrics that can be examined objectively. This study, therefore, implements the analytic hierarchy process (AHP) for the quantitative prioritisation of the control factors involved in a flat end milling manufacturing process. In order to validate the metrics synthesised from the experience of skilled workers, the decision making is followed by a multivariate analysis of the variance based on the general linear model (GLM). The results show that AHP is able to provide fairly reliable metrics about the contribution of process parameters, and the group-wise judgment of qualified experts can improve the consistency of prioritisation.

The Analysis of the Factors Influencing Telecommunication Service Providers Selection on Purchase of Smart Phones

Smart phones become essential goods for our life. As the technology are developing, and the market becomes saturated, it is important to understand the determinants affecting purchase of smart phones. In this paper, to understand these determinants factor analysis and binary logistics regression is used. Toward this, we first define the determinants into 3 categories: customer satisfaction, switching barrier, and switching attractiveness based on literature review. Furthermore, we develop 9 hypotheses to test with survey data using factor analysis and binary logistics regression. The results show that the six factors (data quality, price satisfaction, corporate image, the burden of new contract, attraction of devices and attraction of other competitors) are significant when customers buy smart phones.

An evaluation of federated cloud computing effect with service level

In this paper, we consider a federated cloud computing effect. Cloud computing provides software, platform, and infrastructure as services. Customers pay for the services in a pay-as-you-go model. As an effort of quantifying the effect of cloud computing, this paper evaluates a federated cloud computing network. For the evaluation we studied the simple deterministic demand model and the simple probabilistic demand model. In both cases, the effects of online migration of virtual machines can be clearly identified. Specially, for the probabilistic model we define service level as the proportion of time that the capacity of a data center satisfies the amount of the demand. With the service level concept, the performance of the federation and non-federation can be compared. The models in the paper are basic quantitative ones which can be extended to several other complex models with financial effects.

An Approximation Method for Blocking Probabilities in M/D/1/K1 → ⋅/D/1/K2 Queues

Obtaining exact blocking probabilities for tandem queues with finite capacities is not a trivial problem. In this paper, we propose a computational approximation method using max-plus algebra for computing blocking probability in a Poisson-driven 2-node tandem queue with finite capacities and constant service times. The blocking probability of a finite-capacity queueing system can be obtained from either the tail probability of stationary waiting time or the difference between two expected stationary waiting times at the first node of the corresponding extended 3-node tandem queue. The computational results in this study show that the proposed approach provides a good approximation of the blocking probability, and in particular, it works well under moderately to heavily loaded situations. The proposed approach is not limited to a particular blocking policy, system structure, or service time; hence, it is applicable to general queues with finite buffer capacities and various blocking policies.

Effect of Disease Improvement with Self-Measurement Compliance (Measurement Frequency Level) in SmartCare Hypertension Management Service.

BACKGROUND This studys purpose was to analyze the effect of the SmartCare pilot project, which was conducted in 2011 in South Korea. Recent studies of telehealth mostly compare the intervention group and the control group. Therefore, it is necessary to analyze the disease improvement effect depending on the self-measurement compliance (measurement frequency level) of patients who are receiving the hypertension management services. MATERIALS AND METHODS In the SmartCare center, health managers (nurses, nutritionists, and exercise prescribers) monitored the measurement data transmitted by participants through the SmartCare system. The health managers provided the prevention, consultation, and education services remotely to patients. Of the 231 participants who were enrolled in the study, the final analysis involved 213 individuals who completed their blood pressure measurements and SmartCare services until the end of a 6-month service period. The evaluated measurement group was classified into three groups (Low, Middle, and High) by evenly dividing the monthly average frequency of measurement for 6 months. The evaluation indices were systolic blood pressure (SBP), diastolic blood pressure (DBP), weight, and body mass index (BMI); this information was transmitted through the SmartCare system. RESULTS For changes in the evaluation indices after 6 months compared with the initial baseline, in the Low Group, SBP and DBP slightly decreased, and weight and BMI slightly increased (difference not statistically significant). In the Middle Group, SBP and DBP decreased slightly (difference not statistically significant); however, both weight and BMI decreased (difference statistically significant). In the High Group, SBP, DBP, weight, and BMI decreased (difference statistically significant). CONCLUSIONS Patients who received the SmartCare services with higher measurement frequency levels at home showed greater effectiveness regarding the provided services compared with those patients with lower levels of BP, weight, and BMI control.

A Mathematical Programming Approach for Cloud Service Brokerage

Cloud computing is fast becoming the wave of the future for both home and business computing. Because of this growing acceptance, we can expect an explosion of diverse cloud service providers in the coming years. However, the cloud is not a single entity, rather it is a set of many disconnected islands of application (SaaS), infrastructure (IaaS), and different platform (PaaS) services. Cloud brokering mechanisms are essential to transform the heterogeneous cloud market into a commodity-like service. Cloud service brokers (CSBs) are the new form of business entities to help to aggregate the scattered set of cloud services and make conveniently available to their diverse users. CSBs can reserve a certain percentage of their clients’ (users’) demand and satisfy the remaining portion in an on-demand basis. In doing so, they need to minimize cost of both reserved and on-demand instances as well as the distance of a link between the cloud service provider (CSP) and the user. The study proposes a reservation approach with a mixed integer model to optimizes the cloud service cost and quality.

The Relationship between FDI and Economic Growth: Kazakhstan Case

ABSTRACTIn this paper, we study the relationship between FDI(Foreign Direct Investment) and economic growth in Kazakhstan. For this research, we, first, investigate the factors that affect FDI infow to Kazakhstan since its independence and determine the degree of their influence. Second, we study the impact of FDI per capita on GDP per capita. To achieve these goals, an empirical study is conducted with 18 years data from 1992 to 2009 from World Bank Database. Data are analyzed using multiple linear regression, time series analysis and Granger causality test. The results show that the determinant of FDI is GDP and economic freedom index in Kazakhstan. Economic growth is affected by FDI, too. Specially, FDI is positively related to GDP and economic freedom index. FDI per capitas impact on GDP per capita is 30.4 dollars increase in GDP per capita by one dollar increase in FDI per capital inflow. The results provides useful information for policy makers to improve obtaining large amount of investments and facilitate economic growth.

A study on finding optimal network operators level

This paper considers the optimal staffing level of network operations and management centers in a telecommunication company. This kind of problem is very important for the survival of telecommunication companies since their growth potential is threatened and they need to reduce operating expenditures. To achieve the optimal staffing level, we propose linear programming technique that is one of most frequently used in management science field. We formulate a linear programming model for a network operations management center and give a typical example for the illustration. In addition, we develop a system to implement the linear programming model for a large telecommunication company.