• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권1호
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• pp.22.4-23
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• 2008

• 천문학회보
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• 제34권2호
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• pp.28.1-28.1
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• 2009

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.138-143
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• 2017

A performance analysis for a pulsed plasma thruster(PPT) has been conducted to predict the thrust and current change. Two models were implemented - a one-dimensional lumped circuit analysis model and the Teflon ablation model provided by Michael Keidar. The circuit model incorporating resistance and inductance models was adapted to predict the magnitude of the discharge current. Numerical simulations like current discharge rates with different voltages were reasonably well compared with experimental data. The effects of Teflon ablation on thruster characteristics were investigated.

• 한국멀티미디어학회논문지
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• 제19권1호
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• pp.80-85
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• 2016

It costs high in both memory usage and time consuming to sample the space to compute charge density and calculate electric field on that with large size of plasma data. In real-time and interactive application, accelerating the compute time is critical problem. In this paper, we suggest new method to visualize electric field by using convolution theorem, and the parallel computing to accelerate computing time by using GPGPU. We conduct a simulation that compare running time between the methods with convolution and without convolution. We discussed the method of visualization of multivariate data in three dimensional space using colored volume rendering and surface construction.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.167-170
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• 2005

The mechanism of striation in the coplanar- and matrix-type plasma display panel (PDP) cells has been studied using the particle-in-cell Monte-Carlo Collision (PIC-MCC) model. The striation formation is related to the ionization energy of neutral atoms and the well-like deformation of space potential by space charge distribution. Negative wall charge accumulation by electrons on the MgO surface of the anode region is also one of the key factors for the formation of striation. The clearness of the striation phenomenon in PIC-MCC code in comparison with fluid code can be explained by using nonlocal electron kinetic effect.

• Journal of Astronomy and Space Sciences
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• 제31권1호
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• pp.73-81
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• 2014

A package of space science instruments, dubbed the Instruments for the Study of Space Storms (ISSS), is proposed for the Next Generation Small Satellite-1 (NEXTSat-1), which is scheduled for launch in May 2016. This paper describes the instrument designs and science missions of the ISSS. The ISSS configuration in NEXTSat-1 is as follows: the space radiation monitoring instruments consist of medium energy particle detector (MEPD) and high energy particle detector (HEPD); the space plasma instruments consist of a Langmuir probe (LP), a retarding potential analyzer (RPA), and an ion drift meter (IDM). The space radiation monitoring instruments (MEPD and HEPD) measure electrons and protons in parallel and perpendicular directions to the geomagnetic field in the sub-auroral region, and they have a minimum time resolution of 50 msec for locating the region of the particle interactions with whistler mode waves and electromagnetic ion cyclotron (EMIC) waves. The MEPD measures electrons and protons with energies of tens of keV to ~400 keV, and the HEPD measures electrons with energies of ~100 keV to > ~1 MeV and protons with energies of ~10 MeV. The space plasma instruments (LP, RPA, and IDM) observe irregularities in the low altitude ionosphere, and the results will be compared with the scintillations of the GPS signals. In particular, the LP is designed to have a sampling rate of 50 Hz in order to detect these small-scale irregularities.

• 천문학회보
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• 제38권2호
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• pp.88.1-88.1
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• 2013

We have investigated vertical motions of plasma in the pores and changes of the motions with height by using high time and spatial resolutions data obtained by the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST). We infer the LOS velocity by applying the bisector method to the wings of CaII 854.2 nm line profile. We find that (1) upflow velocity in the pores decreases with height and turns into downward in the upper chromosphere; (2) 3 min and 5 min oscillations are found from the Doppler velocity in the pore at various wavelengths from the wing (${\pm}2.35{\AA}$) to the core (${\pm}1.25{\AA}$) of the CaII line; and (3) power of high (low) frequency oscillation obtained from the CaII intensity increases (decreases) with height. We discuss the physical implications of our results in view of the connection of LOS plasma flows in a concentrated magnetic flux (pore) between the photosphere and the low chromosphere.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2006년도 한국우주과학회보 제15권2호
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• pp.52-52
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• 2006

Many spacecraft failures and anomalies have been attributed to energetic electrons in the Earth's magnetosphere. While the dynamics of these electrons have been studied extensively for several decades, the fundamental question of how they are accelerated is not fully resolved. Proposed theories have not been successful in explaining fast high energy increase such as REE (Relativistic electron enhancement). In this presentation, we show observations of energetic electron precipitation measured by the Korean satellite, STSAT-1 which simultaneously detect (100ev - 20 keV) and (170 - 360 keV) energy electrons at the 680 km orbit, when the RES event observed at the geosynchronous orbit on October 13, 2004. STSAT-1 observed intense electron precipitation in both energy ranges occurred in the midnight sector clearly demonstrating that electrons having wide energy band are injected from the plasma sheet. To make the balance between loss and injection, the injected electron flux should be also large. In this situation, the injected electrons can be trapped into the magnetosphere and produce REE, though they have low e-folding energies. We propose this plasma sheet injection might be the primary source of relativistic electron (1 MeV) flux increases.

• 천문학회지
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• 제56권2호
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• pp.225-229
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• 2023

We investigated an emerging magnetic loop dynamically formed on the Sun, which has the effective footpoint heating source that may play a key role in heating a solar atmosphere with free magnetic energy in it. It is suggested that the heating source could be related to local compression of a plasma in the emerging loop by means of Lorentz force, which converts the magnetic energy to the internal energy of the plasma that is used to reaccelerate a decelerated downflow along the loop, eventually generating the source when the kinetic energy of the downflow is thermalized. By analyzing very high-cadense data obtained from a magnetohydrodynamic simulation, we demonstrate how the local compression is activated to trigger the generation of the heating source. This reveals a characteristic of the emerging loop that experiences a dynamic loop-loop interaction, which causes the local compression and makes the plasma gain the internal energy converted from the magnetic energy in the atmosphere. What determines the characteristic that could distinguish an illuminated emerging loop from a nonilluminated one is discussed.

• 한국항공우주학회지
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• 제47권2호
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• pp.90-97
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• 2019

스파크제트 액츄에이터는 플라즈마 합성 제트 액츄에이터(plasma synthetic jet actuator, PSJA)라고도 불리는 능동 유동 제어 장치로, 초음속 유동의 제어 가능성이 있어 많은 연구가 진행 중이다. 이 액츄에이터는 아크 플라즈마를 이용해 캐비티(cavity) 내부에 에너지를 주입하여 온도와 압력을 상승시킨다. 온도와 압력이 상승한 캐비티에서 오리피스(orifice)를 통해 압력파와 제트가 분출되어 외부 유동에 교란을 준다. 플라즈마의 영향으로 캐비티 유동은 고온, 고압의 평형 유동이 되기 때문에 스파크제트 액츄에이터의 유동 해석을 위해선 공기의 평형 상태를 고려해야 한다. 본 연구에서는 평형 유동의 특성을 고려하여 스파크제트 액츄에이터 유동 해석을 위한 수치해석 프로그램을 개발했다. 개발된 프로그램의 검증으로 문헌에서 얻을 수 있는 실험 결과와 시간에 따른 제트의 위치를 비교했다. 또한 상온, 상압의 무풍에서 액츄에이터의 추력 특성을 분석했다.