• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.2
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• pp.133-139
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• 1982

One of factors that affect combustion in the cylinder of the engine is to keep a greater energy in the ignition system to minimize pollutant emissions and to increase its performance of the low temperature. This paper reviews theoretically the state and input variables of the ignition system from the state transition equation. Effects on characteristics of the system such as primary current, secondary available voltage and spark duration by reducing the pre-resistance from 3.5 to 0 ohm in 12V system is experimentally investigated when the ignition coil has a primary resistance of 1.5 ohms ad the dwell angle of the breaker point is 43.2 degrees (0.75 radian). Advantages and limitations for using the low resistance of the primary circuit are also presented to optimize the performance of the ignition system with the breaker point.

• Biomedical Science Letters
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• v.11 no.1
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• pp.79-84
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• 2005

This study was performed to determine whether postprandial hypertriglyceridemia can affect the endothelial function. Endothelial function was assessed by flow-mediated endothelium-dependent brachial artery vasodilation (FMD) which was defined as percentile changes of diameter. Thirty one patients were enrolled in this study. The serum lipid profiles and FMD were measured at fasting, and after low fat and high fat meals. The serum triglycerides at 2 hours after a high fat meal were significantly increased compared to those measured at 2 hours after a low-fat meal and at fasting state (P<0.05). The FMD was transiently decreased (P<0.0001) from $11.4{\pm}3.2\%$ at fasting state to $6.5{\pm}2.5\%$ after a high-fat meal. The FMD was inversely related with postprandial hypertriglyceridemia (P<0.05). In conclusion, this study may suggest that postprandial hypertriglyceridemia causes endothelial dysfunction.

• Nutrition Research and Practice
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• v.4 no.6
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• pp.528-534
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• 2010

This study explores the influence of health behaviors and individual attributes on adolescent overweight and obesity using data from Wave II (Add Health). Structural equation model/ path analysis using maximum likelihood estimation was utilized to analyze the relationships of health behaviors and attributes with obesity. Results of the model reveal that the causal paths (adolescents' attributes and health behaviors) for overweight and obesity were different for African American and Caucasian adolescents. Generally, African Americans were more susceptible to overweight and obesity than Caucasians. Although increasing levels of vigorous physical activities lowers the risk for obesity among African American and Caucasian adolescents alike, low family SES and being sedentary were associated with overweight and obesity among Caucasians. No significant associations were found among African Americans. Increased hours of sleep at night relate positively with obesity among African Americans. These findings suggest important elements in the consideration of race in developing effective intervention and prevention approaches for curbing the obesity epidemic among U.S. adolescents.

• Journal of the Korea Safety Management & Science
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• v.9 no.3
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• pp.29-40
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• 2007

The state and its proper countermeasures of unreported industrial accidents in Gyungbuk area was investigated throughout a survey research. The goal of the study was to identify major factors that affect the number and causes of unreported accidents. Results from the survey indicated that significant number of unreported accidents exists especially in the small and medium sized industries. Types of the accidents, amount of increase in the insurance cost and level of the governmental enforcement due to the accidents were the major factors for deciding whether to report or not. These results suggested more compromising actions have to be taken by the government for revealing the present but unreported industrial accidents. A more efficient way for preventing the industrial accidents can be considered on the basis of true understanding about real industrial accident statistics.

• Transactions of Materials Processing
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• v.10 no.3
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• pp.223-234
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• 2001

The characteristics of thixoforming process can decrease liquid segregation because of the improvement in fluidity in a globular microstructure state and utilizes flow without an air entrapment. Therefore, in order to obtain the sound parts of metal matrix composites by using thixoforming process which has co-existing solidus-liquidus phase, it is very important to design a die shape property and to obtain the fabrication conditions which affect the unifomity of the solid fraction on unfilling state and various defects throughout the fabricated parts. The die designs and fabrication conditions to obtain the good piston part are proposed for thixoforging process of metal matrix composites. When reheated metal matrix composites billets were transferred to the closed die gate, thixoforging were carried out under the various pressure(60, 80, 100MPa) with controled forging speed. The mechanical properties such as hardness and tensile strength for thixoforged parts have been investigated after T6 heat treatment.

• Journal of Magnetics
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• v.13 no.1
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• pp.1-6
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• 2008

MacDonald and co-workers recently predicted that high current densities could affect the magnetic order of antiferromagnetic (AFM) multilayers, in ways similar to those that occur in ferromagnetic (F) multilayers, and that changes in AFM magnetic order can produce an antiferromagnetic Giant Magnetoresistance (AGMR). Four groups have now studied current-driven effects on exchange bias at F/AFM interfaces. In this paper, we first briefly review the main predictions by MacDonald and co-workers, and then the results of experiments on exchange bias that these predictions stimulated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.57-63
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• 2015

Fault currents characteristics contain decaying DC offset. First cycle peak value of fault currents is higher than steady-state fault current value. These characteristics can affect the operation of protective device. To reduce the asymmetric fault current, the method using a series connection of two hybrid-type Superconducting Fault Current Limiter(SFCL) components, an auxiliary SFCL and a main SFCL, has been proposed. The auxiliary SFCL limits the first half cycle fault current, while main SFCL limits the steady state fault currents. This paper proposed a decision method of the optimal insertion resistance of auxiliary and main SFCL components. To verify the effectiveness of proposed scheme, the various simulations are performed by using Electromagnetic Transient Program(EMTP).

• International Journal of Human Ecology
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• v.6 no.1
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• pp.1-16
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• 2005

Due to increasing life expectancy, Americans live nearly 20 years after retirement. During this period, elderly persons have to stretch finances to manage the level of living without earnings. However, decision making ability decreases with age. One coping strategy for this problem would be seeking help from others. We examine factors affecting elderly persons' assistance use with respect to financial management using the 2000 Health and Retirement Study (N=3,823). It was found that age, education, health status, and ethnicity significantly affect elderly persons' financial management assistance use. The older-olds, those with lower educational attainment and poorer health status were more likely to use financial management assistance. However, Hispanic elderly were less likely to use financial management assistance.

• International Journal of Human Ecology
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• v.13 no.1
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• pp.159-169
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• 2012

This study examined how financial education, impulsive buying, and socio-demographic factors affect saving behavior of 500 Korean college students. The descriptive results show that students who received financial education reported more positive saving behavior compared to students who did not receive financial education in school. The OLS results indicate that all else being equal, students with financial education reported more positive saving behavior than those without financial education. As predictors of saving behavior among Korean college students, the OLS results also reveal that impulsive buying, gender, and age were statistically significant. This study concludes that receiving financial education early, such as in elementary school, plays an important role in determining the saving behavior of Korean college students.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.45-51
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• 2004

Initial flame development and propagation were visualized under different fuel injection timings to relate the initial flame development to the engine stability in a port injection SI engine. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Stratification state was controlled by varying injection timing. Under each injection condition, the flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flame. The flame stability was estimated by the weighted average of flame area, luminosity, and standard deviation of flame area. Results show that stratification state according to injection timing did not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability governs the engine stability and lean misfire limit.