• Journal of Space Technology and Applications
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• v.4 no.1
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• pp.62-73
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• 2024

This study analyzed the effectiveness of orbital change through attitude change in nano-satellites operating in low Earth orbit (LEO) without thrusters, focusing on collision avoidance maneuvers. The results revealed that changes in the satellite's cross-sectional area significantly impact its in-track direction, influenced by the aspect ratio of cross-sectional area change and mission altitude. Notably, satellites at lower altitudes demonstrated significant reduction in collision risks with a small amount of attitude change. Through this study, it is judged that the changing the cross-sectional area through attitude maneuver is a sufficiently suitable method in the operation of nano-satellites without thrusters, and is expected to contribute to improving the safety of satellite operations in the New Space era.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.3
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• pp.267-274
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• 2018

Posterior canal benign paroxysmal positional vertigo (PCBPPV) is the most common disease among patients who visited the st. Carollo hospital dizziness center with the head suddenly feeling rolling or rotational dizziness caused by head and body movements. Most patients showed improvements in symptoms after a single treatment. On the other hand, there are more causes requiring multiple treatments. This study examined the factors affecting the canalithiasis repositioning maneuver for symptom recovery of dizziness, which is posterior BPPV. Dizziness patients who visited the dizziness center of PCBPPV were classified. From March 2008 to November 2010, the cure rate of 165 posterior BPPVs patients was investigated. The success rate after the first, second, third, and further treatments was 57.6%, 17.6%, 10.3%, and 14.5%, respectively. The factors affecting treatment of PCBPPVs included traumatic, medical disease, cerebral infarction, small vessel disease, vestbro basilar artery insufficiency (VBI), cerebrovascular disease, brain disease, and vestibuloplasty (P<0.05). Vomiting, nausea, and syncope can be treated easily by considering the factors affecting these treatments. If the related diseases are combined with the treatment of the canalithiasis repositioning maneuver for symptom recovery of dizziness, the results will show an improvement in daily life that is free from painful dizziness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.548-556
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• 2015

The highly maneuverable fighter aircraft such as F-22, F-16 and F-15have the high maneuverability to maximize the combat performance, whereas the high maneuver characteristics might degrade the pilot's mission efficiency due to fatigue's increase by exposing him to the high gravity and, in the worst case, the pilot could face GLOC (Gravity-induced Loss Of Consciousness). The advanced aerospace company has applied the various technologies to improve the pilot's tolerance to the gravity acceleration, in order to prevent the pilot from entering the situation of the loss of consciousness. Especially, the Anti-G Suit(AGS) equipment to protect the pilot against the high gravity in flight could improve the mission success rate by decreasing the pilot's fatigue in the combat maneuver as well as prevent the pilot from facing GLOC. In this paper, a control algorithm is developed and verified to provide an optimal air pressure to AGS according to the gravity increase during the high performance maneuver. This result is expected, as the key technology, to contribute to the KF-X(Korean Fighter eXperimental), project in the near future.

• Membrane Journal
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• v.33 no.4
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• pp.222-232
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• 2023

In this study, a hollow fiber support membrane was prepared by a non-solvent induced phase separation (NIPS) method using a polysulfone (PSf). The prepared hollow fiber support membrane was coated with PDMS and Pebax to prepare a hollow fiber composite membrane. The prepared composite membrane was measured for permeance and selectivity for pure CO₂, H₂, O₂ and N₂. Gas separation performance of the module having the highest selectivity (CO₂/H₂) among the prepared composite membrane modules was measured according to the change in stage cut using simulated gas. The composition of the simulated gas used at this time was 70% CO₂ and 30% H₂. In the 1 stage experiment, it was possible to obtain values of about 60% of H₂ concentration and 12% of H₂ recovery. In order to overcome the low H₂ concentration and recovery, 2 stage serial test was performed, and through this, it was possible to achieve 70% H₂ concentration and 70% recovery. Through this, it was possible to derive a separation process configuration for CO₂/H₂ separation.

• Journal of Space Technology and Applications
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• v.3 no.2
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• pp.165-198
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• 2023

According to the studies recently published through advanced maui optical and space surveillance technologies (AMOS) Conference 2021, LEO conjunction assessment revolves around not on operating satellites but space debris such as rocket bodies and non-operational satellites, hence suggesting a solution through space traffic management. Against this backdrop, the issue of active debris removal (ADR) has emerged to the surface as an international challenge throughout the globe. In step with this, the United Nations General Assembly approved a resolution calling on nations to halt tests of direct-ascent anti-satellites, to which U.S. and twelve other nations included Republic of Korea were original signatories. ADR techniques are also actively being researched in the civil sector, and these commercial services, if successfully developed, could possibly be utilized for military use as well. As such, this paper will help readers' understanding for the current status of ADR techniques, space threat assessments, on-orbit rendezvous and proximity operations by looking at previous cases, reflecting on space-faring nations' ADR techniques and its development probability in relation to space weapons. As a conclusion, this study will propose the needs of developing space propulsion system by understanding Space Maneuver Warfare in preparation for the future space battlefield.

• Journal of Astronomy and Space Sciences
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• v.13 no.1
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• pp.48-54
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• 1996

The generalized linear impulsive correction problem is applied to make a linear programming problem for optimizing trajectory of an orbiting spacecraft. Numerical application for the stationkeeping maneuver problem of geostationary satellite shows that this problem can efficiently find the optimal solution of the stationkeeping parameters, such as velocity changes, and the points of impulse by using the revised simplex method.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.62.1-62.1
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• 2008

• Bulletin of the Korean Space Science Society
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• 1998.10a
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• pp.38-38
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• 1998

No Abstract.See Full-text

• Bulletin of the Korean Space Science Society
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• 1997.04a
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• pp.30.1-30
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• 1997

No Abstract.See Full-text

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.255-256
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• 2013