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Variation of Floating Potential in the Topside Ionosphere Observed by STSAT-1
Junhyun Lee,Ensang Lee,Jaejin Lee,Khan-Hyuk Kim,Jongho Seon,Dong-Hun Lee,Ho Jin,Eung-Hyun Kim,Hyun-Jin Jeon,Seong-Bin Lim,Taeyoun Kim,Jaewoong Jang,Kyung-Duk Jang,Kwangsun Ryu 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4
In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.
Seunghwi Jo,Si-Bog Park,Mi Jung Kim,Tai Kon Kim,Kyeong Il Park,Junhyun Sung,Un Jin Park,Yee Suk Kim,Byeong Jik Kang,Kyu Hoon Lee 대한재활의학회 2016 Annals of Rehabilitation Medicine Vol.40 No.6
Objective To determine whether there was a difference in balance, proprioception, and skeletal muscle mass among patients who undergo hip fracture surgery relative to and elective total hip replacement (THR). Methods Thirty-one THR patients were enrolled. The patients were categorized into two groups: fracture group (n=15) and non-fracture group (n=16). Berg Balance Scale (BBS) was used to balance the proprioception of the hip joint while a joint position sense (JPS) test was used to evaluate it. Skeletal muscle mass was measured by bioelectrical impedance analysis and expressed as a skeletal muscle mass index (SMI). Quality of life (QOL) was also assessed using a 36-item short form health survey (SF-36). All tests were assessed at 3 months after the surgery. An independent t-test was used to compare the fracture group and non-fracture group. Spearman correlation was used to identify the correlation of each variable. Results In an independent t-test, the BBS score of patients undergoing elective surgery was higher than the BBS score of patients undergoing hip fracture surgery. There was a significant correlation between the BBS and JPS score after a THR. SMI also correlated with the score of BBS.Conclusion It seems that THR patients undergoing surgery for a hip fracture might have more trouble balancing than elective THR patients. Therefore THR patients undergoing hip fracture surgery might need more care during rehabilitation.
Korea Pathfinder Lunar Orbiter Magnetometer Instrument and Initial Data Processing
Wooin Jo,Ho Jin,박현후,장윤호,이성환,김관혁,Ian Garrick-Bethell,신재혁,Seul-Min Baek,Junhyun Lee,손대락,김은혁 한국우주과학회 2023 Journal of Astronomy and Space Sciences Vol.40 No.4
The Korea Pathfinder Lunar Orbiter (KPLO), the first South Korea lunar exploration probe, successfully arrived at the Moon on December, 2022 (UTC), following a 4.5-month ballistic lunar transfer (BLT) trajectory. Since the launch (4 August, 2022), the KPLO magnetometer (KMAG) has carried out various observations during the trans-lunar cruise phase and a 100 km altitude lunar polar orbit. KMAG consists of three fluxgate magnetometers capable of measuring magnetic fields within a ± 1,000 nT range with a resolution of 0.2 nT. The sampling rate is 10 Hz. During the originally planned lifetime of one year, KMAG has been operating successfully while performing observations of lunar crustal magnetic fields, magnetic fields induced in the lunar interior, and various solar wind events. The calibration and offset processes were performed during the TLC phase. In addition, reliabilities of the KMAG lunar magnetic field observations have been verified by comparing them with the surface vector mapping (SVM) data. If the KPLO’s mission orbit during the extended mission phase is close enough to the lunar surface, KMAG will contribute to updating the lunar surface magnetic field map and will provide insights into the lunar interior structure and lunar space environment.