Search

Iodide ion selective poly(aniline) solid contact electrode based on quinine-Cu ionophore as a sensing material has been successfully developed. The electrode exhibits good linear response of 52.0 mV/decade (at 20 ± 0.2°C, r = 0.9998) within the concentration range of 1 × 10-1 × 10 M KI. The composition of this electrode was quinine-Cu 2.0: PVC 30.0: bis(2-ethylhexyl)sebacate 68.0 (mass). This plasticizer provides the best response characteristics. The electrode shows good selectivity for iodide ion in comparison with any other anions and is suitable for use with aqueous solutions of pH 3.3-9.4. The standard deviations of the measured EMF difference were ±1.4 and ±1.3 mV for iodide sample solutions of 1.0 × 10 M and 1.0 × 10 M, respectively. The stabilization time was less than 10 min and response time was less than 15 sec. [ABSTRACT FROM AUTHOR]

This paper applies stochastic production frontier models with time-varying technical efficiency to a panel data set including hitherto unavailable information on team wage bills from the first division in German professional soccer (the 'Bundesliga') covering the years 1981-2003. We demonstrate that individual teams experience significant variation in technical efficiency over an extended period of 22 seasons while the league's average level of efficiency remains constant over time. More detailed analyses reveal that, first, the decision to fire or to retain the head coach is mainly influenced by changes in managerial efficiency between two adjacent seasons and, second, relegated teams on average experience considerable reductions in technical efficiency compared to the previous season. [ABSTRACT FROM AUTHOR]

Since the Japanese National Baseball team won the inaugural World Baseball Classic, 'small ball' has been accepted, at least by the media, as a mainstream form of baseball management in Korea. Small ball refers to a manager's active intervention or strategy implementation in baseball games. In general, the frequency of managers' orders for play actions such as a sacrifice bunt is higher in Asian baseball than in North American baseball. This paper attempts to statistically test the hypothesis that small ball is effective in winning games by using data from Korean baseball. The panel data analysis of a stochastic production frontier model presents somewhat mixed empirical results, but the overall evidence suggests that small ball actually has detrimental effects on the number of runs scored. [ABSTRACT FROM AUTHOR]

Operations management in a complex manufacturing environment is practiced hierarchically: production planning and scheduling in sequence since the integrated approach is not efficient and practical. Production targets and allocation to the equipment are determined in the planning procedure by considering the only the critical factors, and the detailed scheduling is determined with more information needed to accomplish the production targets provided in the planning step. There is always, therefore, a gap between the planning and scheduling procedure, and some control parameters or factors are used to control those gaps. In this paper an approach connecting two procedures is suggested, which can be applied in the EDS (electrical die sorting) or the probe process in the semiconductor manufacturing. The EDS process requires very flexible operation management since the manufacturing processing time is relatively short and the supply of upstream fabrication and the demand of downstream assembly have to be met simultaneously. Daily planning and scheduling procedure are modeled to minimize the tester change-over within the daily target. Because of the relatively long setup change-over time, daily planning and scheduling have to be performed so that the time needed for the device and probe card change is minimized as possible. Mathematical programming is suggested for the problem, and the modified model is developed which can be solved in a practical computational time on a daily base. The scheduling heuristic with the planning data obtained from the suggested model, is designed, and their performance is evaluated through the computational experiment. [ABSTRACT FROM AUTHOR]

This paper discusses the problem of determining workload in a semiconductor fabrication line for providing robust production control. A mathematical model is proposed to determine the amount of wafers to be processed on equipment in a photolithography process where the setup time is incurred if the type of wafers is changed on the equipment. The objective of the model is to control the fabrication line by maintaining the target work-in-process (WIP) level as close as possible for the purpose of short cycle time and by minimizing the setup time loss for maximal throughput. The proposed model is formulated using mixed integer programming (MIP) to minimize the weighted sum of two objective functions. A heuristic approach is suggested using linear relaxation and its adjustment. Performances are evaluated for the optimal solution with computational cost and for the heuristics. It is shown that the heuristics give good solutions which are 10% away, on average, from the optimal solution, but which can be obtained in a few seconds. [ABSTRACT FROM AUTHOR]

Abstract  The aims of this study were to establish reference data for bone mineral density (BMD) at central skeletal sites using Lunar dual-energy X-ray absorptiometry (DXA), and to estimate the age-and sex-specific prevalence of osteoporosis in a Korean population. We performed a population-based, cross-sectional study. The subjects were 4148 (1810 men and 2338 women) Korean adults, aged 20–79 years. The BMD for central sites (lumbar spine, femoral neck, trochanter, and Ward’s triangle) were measured by DXA. The standardized prevalence of osteoporosis among individual aged 50–79 years in lumbar spine, femoral neck, Ward’s triangle, and trochanter was 40.1%, 12.4%, 28.4%, and 4.4% in women and 6.5%, 5.9%, 3.7%, and 1.6% in men, respectively. In women, peak BMD occurred in the age range 40–49 years for the femoral neck and trochanter, 30–39 years for the lumbar spine, and 20–29 years for Ward’s triangle. In men, peak BMD values were observed at 20–29 years for all measured sites. This study establishes a normative database for BMD at central skeletal sites using dualenergy X-ray absorptiometry and provides more reliable information on the prevalence of osteoporosis in Korea. [ABSTRACT FROM AUTHOR]

Abstract  We examined the relative contribution of body composition to bone mineral density (BMD) at various sites in 1406 Korean rural men and women, aged 19–80 years, from July to August 2004. The BMD was measured at peripheral (distal forearm and calcaneus) and central (lumbar spine at L1–L4, femoral neck, trochanter, and Ward's triangle) using dual-energy X-ray absorptiometry. In multivariate analyses, the linear regression models were adjusted for relevant covariates. In premenopausal women, only lean mass had a significant positive correlation with BMD at all sites. In postmenopausal women, fat mass was significantly positively correlated with BMD at all sites, except the Ward's triangle; fat mass was the only determinant of BMD at the lumbar, distal forearm, and calcaneus sites, whereas both lean and fat mass contributed to BMD at the hip, with the effect of lean mass being slightly greater than that of fat mass. In younger men, lean mass had a significant positive contribution to BMD at all sites, whereas fat mass appeared to contribute negatively to BMD at all sites, except the calcaneus. In older men, lean mass made a significant positive contribution to the BMD at all sites; fat mass also made a significant positive contribution to the BMD at the forearm and calcaneus. These data indicate that in the Korean rural population, lean mass may be an important determinant of the BMD, whereas fat mass may contribute positively to BMD only in postmenopausal women and older men. [ABSTRACT FROM AUTHOR]

Thin film transistor and liquid crystal display (TFT-LCD) fabrication manufacturing is characterised as a re-entrant process, in which a similar sequence of steps is repeated several times. Production control for the re-entrant process is complex, since, without intelligent control, it may incur the congestion of WIP or equipment idleness because of the work in progress (WIP) shortage. In this paper, three kinds of control policies are suggested: push, push-pull and pull types. Exact formulations using linear programming are given, and their performances of solutions are evaluated. It is shown that a pull type control policy gives stable throughput and delivery satisfaction at a small cost and with less production. A push type policy outperforms the other two types in the throughput and manufacturing cycle time. [ABSTRACT FROM AUTHOR]