• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.147-158
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• 2020

In this paper, we will review the thruster based reaction wheel momentum dumping method for low Earth orbit satellite. Thruster based momentum dumping is widely used in GEO satellites by performing momentum dumping and attitude control using thrusters at the specific time. LEO satellite should perform momentum dumping at any time, thus it is not appropriate to use GEO satellite's momentum dumping method. In this research, we will review the method for LEO satellite, which perform momentum dumping always and use reaction wheels for attitude control during dumping. To reduce thruster's valve on and off counts, we propose to use the maximum pulse width for thruster operation. To prevent attitude error increase by thrusters, we adjust the thruster operation interval. Through simulation, we verify the proposed method's effects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.371-378
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• 2019

High precision pointing satellite uses the reaction wheels for the attitude control and their momentum dumping is performed by the three magnetic torquers. In this paper, the effects of one magnetic torquer's failure on the momentum dumping will be reviewed. When the satellite on the high inclination angle orbit holds LVLH (Local Vertical Local Horizontal) attitude, pitch axis magnetic torquer failure causes the momentum dumping failure. But in case of other torquer's failure, momentum dumping is still possible with degraded dumping performance. When pitch axis magnetic torquer fails, momentum dumping is possible by changing the satellite attitude. This paper propose the satellite attitude change to make the momentum dumping possible when pitch axis magnetic torquer fails. In addition, if torquer arrangement is modified, momentum dumping is always possible regardless of any torquer's failure.

• International Commerce and Information Review
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• v.14 no.1
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• pp.3-22
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• 2012

China has used the Antidumping policy as a trade protection tool against Japanese products due to reduce the deficit of trade balance of payment, boost the economic growth and protect its weak industries. This paper investigates whether there is a connection between the China's macroeconomic activity and pressures for protection to Japanese products under antidumping measures with using the current data that come from the WTO, World Bank for 1997 to 2010. The result suggests that pressures for protection under Antidumping measure against exporting of Japanese products to China have increased during periods of macroeconomic weakness like high unemployment, larger deficit of trade balance and decreased during periods of macroeconomic strength.

• Product Safety
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• s.82
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• pp.44-47
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• 2000

• International Commerce and Information Review
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• v.15 no.3
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• pp.245-262
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• 2013

The transaction size between South Korea and the European Union (EU) had increased by more than two times among 2003 to 2008. With rapid growth of transaction, the EU was becoming important transaction object of South Korea gradually. EU has used the Antidumping policy as a trade protection tool against Korean products due to reduce the deficit of trade balance of payment, boost the economic growth and protect its weak industries. This paper investigates whether there is a connection between the EU's macroeconomic activity and pressures for protection to Korean products under antidumping measures with using the current data that come from the WTO, World Bank for 2004 to 2012. The result suggests that pressures for protection under Antidumping measure against exporting of Korean products to EU have increased during periods of macroeconomic weakness of low GDP growth, larger deficit of trade balance, however, has not significantly affected during periods of high unemployment.

• International Commerce and Information Review
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• v.16 no.1
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• pp.117-142
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• 2014

China having largest market in the world, has been criticized by its trading partner countries due to its unfair trade practices, particularly in the field of anti-dumping regulation. The main reasons for such criticism seem to come from the incomplete anti-dumping law as instrument to protect the industry concerned. In 2001, though new anti-dumping law was established to replace the former one by revising it to meet the needs for economic development which should be secured for china to take part in the competition world as the new member of WTO. The provisions concerned have been evaluated not to be sufficient and efficient from the viewpoint of the safeguard mechanism, while are required to be modified to meet the real world of international trade law. I consider that as the biggest partner of chinese trade activity, we will need to maintain a well understanding of the Chinese anti-dumping regulations. So this report conducts the Chinese anti-dumping regulations, compares between the chinese regulations and the WTO agreement, and studies deeply in to the problems and the improvements of the Chinese anti-dumping regulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.81-88
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• 2005

This paper analyzes the fuel consumption for the momentum dumping of the COMS which has a single solar array system. First, numerical analyses are conducted to find an optimal momentum dumping time considering the COMS configuration. It is assumed that the momentum dumping is conducted once a day and at a fixed time of a day. Secondly, in an effort to reduce the momentum dumping fuel consumption, this paper proposes a new approach which combines the momentum dumping and the ordinary north/south stationkeeping. Finally, to evaluate the proposed technique, the stationkeeping simulations are conducted and analyzed.

• Journal of Korean Electronics
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• v.15 no.1
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• pp.110-115
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• 1995

• Journal of Korean Electronics
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• v.15 no.10
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• pp.13-21
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• 1995

• Journal of Korean Electronics
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• v.15 no.2
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• pp.74-82
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• 1995