• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.306-313
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• 2004

The microwave discharge ion engine generates plasmas of both the main ion source and the neutralizer using 4㎓ microwave without discharge electrodes and hollow cathodes, so that long life and durability against oxygen and air are expected. The MUSES-C “HAYABUSA” asteroid explorer installing four microwave discharge ion engines “$\mu$10s” was launched into deep space by M-V rocket No.5 on May 9, 2003. After vacuum exposure and several runs of baking for reduction of residual gas the ion engine system established the continuous acceleration of the spacecraft toward the asteroid “ITOKAWA”. The Doppler shift measurement of the communication microwave revealed the performance of ion engines, which is 8mN thrust force for a single unit with 3,200sec specific impulse at 23mN/㎾ thrust power ratio. At the end of 2003 the accumulated operational time exceeded 8,000 hour and unit. HAYABUSA will execute the Earth swing-by on June 2004 and arrive at the asteroid in 2005 and return to Earth in 2007.

• Bulletin of the Korean Space Science Society
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• 2007.10a
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• pp.139-143
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• 2007

Electric propulsion has become a cost effective and sound engineering solution for many space applications. The success of SMART-1 and MUSES-C developed by European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) each proved that even small spacecraft could accomplish planetary mission with electric propulsion systems. A small electric propulsion system which is Hall effect thruster like SMART-1 is under development by SaTReC and GDPL (Glow Discharge Plasma Lab.) in KAIST for the next microsatellite, STSAT-3. To achieve optimized propulsion system, it is very necessary to understand plasma motions of Hall effect thruster. In this paper, we try to approach comprehensive plasma model with the particle simulation complementary to Particle In Cell (PIC) simulation. We think these two different approaches will help experimenters to optimize Hall effect thruster performances.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.314-317
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• 2004

On 9/5/2003, the planet probe “HAYABUSA” as MUSES-C project was launched by The Institute of Space and Astronautical Science. “HAYABUSA” has microwave discharge ion engines and these engines are characterized by their high efficiency and specific impulse in comparison with chemical engine. A large ion engine can be used as a planet explorer, while a small ion engine can be used as attitude control of small satellite. We have been developing a high thrust density microwave discharge ion engine using “Multi-Monopole Antenna”. The performance of this engine are: ion cost of 344W/A, propellant utilization efficiency of 52% and thrust density of 0.055mN/$\textrm{cm}^2$ for Kr gas flow rate of 2.5sccm, microwave(2.45㎓) power of 32W and acceleration voltage of l.4㎸.

• Nutritional Sciences
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• v.7 no.4
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• pp.247-253
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• 2004

This study has investigated the effect of dietary attitudes on nutritional status of nurses living in Kyungnam province. A total of 249 muses working at hospitals in the Kyungnam area participated in this study. The general characteristics and dietary attitudes of the subjects were surveyed using a self-administered questionnaire, and nutrient intakes were examined using one day 24-hour recall method from November 14 to December 20, in 2001. The data of nutrient intakes were analyzed by the Computer Aided Nutritional Analysis Program and then the diet quality was estimated using the Index of Nutritional Quality (INQ). The subjects were classified as the high score group (17.3 %), medium score group (54.2%), and low score group (28.5%) based on dietary attitude score. The results were as follows: Average age of subjects was 27.1 years old, average nursingexperience was 5.7 years, and 70.7% of the subjects graduated from a junior college. The rate of shift work (45.4%) and non-shift work (54.6%) were similar. The average score on dietary attitudes in thehigh score group was 78.8, and those in he medium score group and in the low score group were 58.6 and 40.8 out of 100 points respectively. The average intake of energy (p < 0.001), carbohydrate (p < 0.001), protein (p < 0.05), animal protein (p < 0.01), animal fat (p < 0.05), vitamin $B_1$ (p < 0.01), vitamin $B_2$ (p < 0.0l), niacin (p < 0.001), Ca (p < 0.001), Fe (p < 0.001), animal Fe (p < 0.01), P (p < 0.001), and crude fiber (p < 0.00l), were significantly higher in the high score group than those in the medium score group and low score group. In the high score group, the average intake of protein, vitamin $B_1$, niacin, vitamin C and P were above 125% of the Korean RDA, and in medium score group, those of vitamin C and P, and in low score group, that of vitamin C were above 125% of the Korean RDA. In the high score group, nutrient of intake below 75% of the Korean RDA was Ca, and those in medium score group were vitamin $B_2$, Ca, and Fe, and those in low score group were energy, vitamin $B_2$, Ca and Fe. The intake ratio of Ca and P showed an unbalanceof 1:2, and that of animal protein/plant protein, and that of animal fat/plant fat were high (1.45-1.64) in all group;. The dietary attitude had a positive correlation (p < 0.00l) with nutrition intake except vitamin A and vitamin C.