ObjectivesThe purpose of this study was to identify the risk factors of metabolic syndrome (MS) and to analyze the relationship between the risk factors of MS and medical cost of major diseases related to MS in Korean workers, according to the scale of the enterprise.MethodsData was obtained from annual physical examinations, health insurance qualification and premiums, and health insurance benefits of 4,094,217 male and female workers who underwent medical examinations provided by the National Health Insurance Corporation in 2009. Logistic regression analyses were used to the identify risk factors of MS and multiple regression was used to find factors associated with medical expenditures due to major diseases related to MS.ResultThe study found that low-income workers were more likely to work in small-scale enterprises. The prevalence rate of MS in males and females, respectively, was 17.2% and 9.4% in small-scale enterprises, 15.9% and 8.9% in medium-scale enterprises, and 15.9% and 5.5% in large-scale enterprises. The risks of MS increased with age, lower income status, and smoking in small-scale enterprise workers. The medical costs increased in workers with old age and past smoking history. There was also a gender difference in the pattern of medical expenditures related to MS.ConclusionsHealth promotion programs to manage metabolic syndrome should be developed to focus on workers who smoke, drink, and do little exercise in small scale enterprises.

Trends of traction motor of railway vehicles have been shifted from induction motors to permanent magnet motors. Recently, studies have been conducted on dysprosium-free permanent magnets. Dysprosium is a heavy rare earth element that has a great impact on performance of motors. However, dysprosium affects the coercive force of a permanent magnet and can produce irreversible demagnetization. Conventional studies have focused on improving the performance of motors using permanent magnets without heavy rare earth elements. In this study, a robust rotor design process includes the way to restrain irreversible demagnetization using a dysprosium-free permanent magnet. First, the irreversible magnetization of bar-type and V-type magnets, which are basic models of interior permanent magnet synchronous motors, is analyzed. Next, expected demagnetized parts of the main magnets are used as a submagnets, which make magnetic field bypass both sides of the submagnets, and magnets are added in submagnets regions to compensate gap of performance between target model and double type models. Finally, parameter analysis is performed on the design variables of the main magnet. The proposed the robust design process to restrict irreversible demagnetization proves its validity through finite element analysis.

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