Younghak Lee

Dynamic Simulation of Discontinuously Arranged Electromagnets for Passive Tray Levitation

For a highly clean vacuum environment, magnetic levitation is plausible technology because of its noncontact nature. Especially, due to the potential occurrence of an electric spark in spite of low voltage in a vacuum a passive tray without any circuits is required. In consideration of spatial limitation and cost reduction, the electromagnets of the passive tray levitation should be located discontinuously. This paper presents the characteristic analysis of the passive tray levitation system according to an interval of discontinuously arranged electromagnets. For doing this, the 3D dynamic model, which consists of the mechanical components, joints, and force elements, is proposed to predict the levitation stability.

Behavior of Pore Water Pressure of Agricultural Reservoir According to Raising Embankment

In this study, an experiment with large-scale model was performed according to raising embankment in order to investigate the cause of collapse by a change in water level of reservoir. Also, the settlement and pore water pressure by high water level and a rapid drawdown were compared and analyzed. After raising embankment for inclined core, there was no infiltration by leakage. For the vertical core, the pore water pressure showed a largely change by faster infiltration of pore water than in the inclined core. In a rapid drawdown, inclined core was remained stable but vertical core showed a largely change in pore water pressure. A settlement after a raising embankment showed a larger measure of settlement than before the raising embankment. The leakage quantity before a raising embankment and an inclined extension showed no leakage. Leakage in vertical extension was measured 160 . From the result, a instrument system that can accurately estimate a change of pore water pressure shall be established for a rational maintenance and stabilization of raising embankment for agricultural reservoir.

Passive Maglev Carrier Control with Consideration of Pitch Motion

This research aims to develop core technologies for passive carrier (no power in carrier itself) transfer system. The technologies are passive levitation, propulsion, and guidance, which can be great benefits for semiconductor and display manufacturing industries. Passive maglev carrier is necessary to precise position control for quiet and stable transfer operation. However, the structural characteristics of carrier and the installation errors of gap sensors cause the pitch motion. Hence, the controller design in consideration of pitch motion is required. This study deals with the reduction control of carrier pitch motion. PDA controller and PDA controller with pitch control are proposed to compare the pitch angle analysis. The pitch angle and the levitation precision are measured by experiment. Finally, the optimized design of pitch controller is presented and the effects are discussed. † Corresponding Author, einses@kimm.re.kr C 2016 The Korean Society of Mechanical Engineers 이영학 · 김창현 · 하창완 · 박도영 · 양석조 · 임재원 214

The Eosinophil Count Tends to Be Negatively Associated with Levels of Serum Glucose in Patients with Adrenal Cushing Syndrome

Background Cushing syndrome is characterized by glucose intolerance, cardiovascular disease, and an enhanced systemic inflammatory response caused by chronic exposure to excess cortisol. Eosinopenia is frequently observed in patients with adrenal Cushing syndrome, but the relationship between the eosinophil count in peripheral blood and indicators of glucose level in patients with adrenal Cushing syndrome has not been determined. Methods A retrospective study was undertaken of the clinical and laboratory findings of 40 patients diagnosed with adrenal Cushing syndrome at Chungnam National University Hospital from January 2006 to December 2016. Clinical characteristics, complete blood cell counts with white blood cell differential, measures of their endocrine function, description of imaging studies, and pathologic findings were obtained from their medical records. Results Eosinophil composition and count were restored by surgical treatment of all of the patients with adrenal Cushing disease. The eosinophil count was inversely correlated with serum and urine cortisol, glycated hemoglobin, and inflammatory markers in the patients with adrenal Cushing syndrome. Conclusion Smaller eosinophil populations in patients with adrenal Cushing syndrome tend to be correlated with higher levels of blood sugar and glycated hemoglobin. This study suggests that peripheral blood eosinophil composition or count may be associated with serum glucose levels in patients with adrenal Cushing syndrome.

Design and control characteristics of guidance system for passive maglev transport system

Recent OLED display manufacturing process requires non-contact conveyor systems not generating particles to increase productivity. To avoid supplying power and heating in vacuum, a passive maglev transport system can be a promising solution because it has no actuators in moving carriers and all actuating electromagnets are installed on the ground. In this paper, we deal with the design and control characteristics of the guidance system for the passive maglev transport system. The proposed guidance system can generate bi-directional motion using one electromagnet and the guidance system is designed and analyzed in details using FEM tools. The guidance control characteristics were analyzed through impact tests using the manufactured passive maglev transport system.