bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrity Assessment and Verification Procedure of Angle-only Data for Low Earth Orbit Space Objects with Optical Wide-field PatroLNetwork (OWL-Net)
Authors: Choi Jin , Jo Jung Hyun , Kim Sooyoung , Yim Hong-Suh , Choi Eun-Jung , Roh Dong-Goo , Kim Myung-Jin , Park Jang-Hyun , Cho Sungki
Published: May 2023

The Optical Wide-field patroL-Network (OWL-Net) is a global optical network for Space Situational Awareness in Korea. The primary operational goal of the OWL-Net is to track Low Earth Orbit (LEO) satellites operated by Korea and to monitor the Geostationary Earth Orbit (GEO) region near the Korean peninsula. To obtain dense measurements on LEO tracking, the chopper system was adopted in the OWL-Net’s back-end system. Dozens of angle-only measurements can be obtained for a single shot with the observation mode for LEO tracking. In previous work, the reduction process of the LEO tracking data was presented, along with the mechanical specification of the back-end system of the OWL-Net. In this research, we describe an integrity assessment method of time-position matching and verification of results from real observations of LEO satellites. The change rate of the angle of each streak in the shot was checked to assess the results of the matching process. The time error due to the chopper rotation motion was corrected after re-matching of time and position. The corrected measurements were compared with the simulated observation data, which were taken from the Consolidated Prediction File from the International Laser Ranging Service. The comparison results are presented in the In-track and Cross-track frame.
Reliability Analysis of the 300W GaInP/GaAs/Ge Solar Cell Array Using PCM
Authors: Shin Goo-Hwan , Kwon Se-Jin , Lee Hu-Seung
Published: May 2023

Spacecraft requires sufficient power in orbit to perform its mission. So as to
comply with system requirements, the sufficient power should be made by a solar cell
array by photovoltaic power conversion. A life time of space program depends on its
mission considering parts reliability and parts grade. Based on the mission life time,
power equipment might be designed to meet specifications. In outer space, solar cell
array might generate the dc power by photovoltaic conversion effects and GaInP/GaAs/Ge
solar cells are used in this study. Space programs that require more than five years
should select parts for high reliability applications. Therefore, reliability analysis
for high reliability applications should be performed to check its fulfilment of the
requirements. This program should also require more five years for its mission and we
performed its analysis using parts count method (PCM) for its reliability. Finally, we
performed reliability analysis and obtained quantitative figures found out 99.9%. In
this study, we presented the reliability analysis of the 300W GaInP/GaAs/Ge solar cell
array.
New Light Curves and Orbital Period Investigations of the Interacting Binary System
UV Piscium
Authors: Jeong Min-Ji , Han Wonyong , Kim Chun-Hwey , Yoon Joh-Na , Kim Hyoun-Woo
Published: May 2023

UV Psc is a typical RS CVn type system undergoing dynamic chromosphere activity.
We performed photometric observations of the system in 2015 and secured new BVR light
curves showing well-defined photometric waves. In this paper, we analyzed the light
curves using Wilson-Devinney binary code and investigated the orbital period of the
system. The combination of our light curve synthesis with the spectroscopic solution
developed by previous investigators yielded the absolute parameters as: M1 = 1.104 ±
0.042 Mⵙ, R1 = 1.165 ± 0.025 Rⵙ, and L1 = 1.361 ± 0.041 Lⵙ for the primary star, and M2
= 0.809 ± 0.082 Mⵙ, R2 = 0.858 ± 0.018 Rⵙ, and L2 = 0.339 ± 0.010 Lⵙ for the secondary
star. The eclipse timing diagram for accurate CCD and photoelectric timings showed that
the orbital period may vary either in a downward parabolic manner or a quasi-sinusoidal
pattern. If the latter is adopted as a probable pattern for the period change, a more
plausible account for the cyclic variation may be the light time effect caused by a
circumbinary object rather than an Applegate-mechanism occurring via variable surface
magnetic field strengths.
Variation of the Hemispheric Asymmetry of the Equatorial Ionization Anomaly with
Solar Cycle
Authors: Kwak Young-Sil , Kil Hyosub , Lee Woo Kyoung , Yang Tae-Yong
Published: May 2023

In solstices during the solar minimum, the hemispheric difference of the
equatorial ionization anomaly (EIA) intensity (hereafter hemispheric asymmetry) is
understood as being opposite in the morning and afternoon. This phenomenon is explained
by the temporal variation of the combined effects of the fountain process and
interhemispheric wind. However, the mechanism applied to the observations during the
solar minimum has not yet been validated with observations made during other periods of
the solar cycle. We investigate the variability of the hemispheric asymmetry with local
time (LT), altitude, season, and solar cycle using the electron density taken by the
CHAllenging Minisatellite Payload satellite and the global total electron content (TEC)
maps acquired during 2001–2008. The electron density profiles provided by the
Constellation Observing System for Meteorology, Ionosphere, and Climate satellites
during 2007–2008 are also used to investigate the variation of the hemispheric asymmetry
with altitude during the solar minimum. During the solar minimum, the location of a
stronger EIA moves from the winter hemisphere to the summer hemisphere around 1200–1400
LT. The reversal of the hemispheric asymmetry is more clearly visible in the F-peak
density than in TEC or in topside plasma density. During the solar maximum, the EIA in
the winter hemisphere is stronger than that in the summer hemisphere in both the morning
and afternoon. When the location of a stronger EIA in the afternoon is viewed as a
function of the year, the transition from the winter hemisphere to the summer hemisphere
occurs near 2004 (yearly average F10.7 index = 106). We discuss the mechanisms that
cause the variation of the hemispheric asymmetry with LT and solar cycle.
Angles-Only Initial Orbit Determination of Low Earth Orbit (LEO) Satellites Using
Real Observational Data
Authors: Hwang Hyewon , Park Sang-Young , Lee Eunji
Published: May 2023

The Optical Wide-field patroL-Network (OWL-Net) is a Korean optical space
surveillance system used to track and monitor objects in space. In this study, the
characteristics of four Initial Orbit Determination (IOD) methods were analyzed using
artificial observational data from Low Earth Orbit satellites, and an appropriate IOD
method was selected for use as the initial value of Precise Orbit Determination using
OWL-Net data. Various simulations were performed according to the properties of
observational data, such as noise level and observational time interval, to confirm the
characteristics of the IOD methods. The IOD results produced via the OWL-Net
observational data were then compared with Two Line Elements data to verify the accuracy
of each IOD method. This paper, thus, suggests the best method for IOD, according to the
properties of angles-only data, for use even when the ephemeris of a satellite is
unknown.
Precise Orbit Determination Based on the Unscented Transform for Optical
Observations
Authors: Hwang Hyewon , Lee Eunji , Park Sang-Young
Published: May 2023

In this study, the precise orbit determination (POD) software is developed for
optical observation. To improve the performance of the estimation algorithm, a nonlinear
batch filter, based on the unscented transform (UT) that overcomes the disadvantages of
the least-squares (LS) batch filter, is utilized. The LS and UT batch filter algorithms
are verified through numerical simulation analysis using artificial optical
measurements. We use the real optical observation data of a low Earth orbit (LEO)
satellite, Cryosat-2, observed from optical wide-field patrol network (OWL-Net), to
verify the performance of the POD software developed. The effects of light travel time,
annual aberration, and diurnal aberration are considered as error models to correct
OWL-Net data. As a result of POD, measurement residual and estimated state vector of the
LS batch filter converge to the local minimum when the initial orbit error is large or
the initial covariance matrix is smaller than the initial error level. However, UT batch
filter converges to the global minimum, irrespective of the initial orbit error and the
initial covariance matrix.
Swarm Satellite Observations of the 21 August 2017 Solar Eclipse
Authors: Hussien Fayrouz , Ghamry Essam , Fathy Adel , Mahrous Salah
Published: May 2023

On 21 August 2017, during 16:49 UT and 20:02 UT period, a total solar eclipse
started. The totality shadow occurred over the United States in time between ~17:15 UT
and ~18:47 UT. When the solar radiation is blocked by the moon, observations of the
ionospheric parameters will be important in the space weather community. Fortunately,
during this eclipse, two Swarm satellites (A and C) flied at about 445 km through lunar
penumbra at local noon of United States in the upper ionosphere. In this work, we
investigate the effect of the solar eclipse on electron density, slant total electron
content (STEC) and electron temperature using data from Swarm mission over United
States. We use calibrated measurements of plasma density and electron temperature. Our
results indicate that: (1) the electron density and STEC have a significant depletion
associated with the eclipse; which could be due to dominance of dissociative
recombination over photoionization caused by the reduction of ionizing extreme
ultraviolet (EUV) radiation during the eclipse time (2) the electron temperature
decreases, compared with a reference day, by up to ~150 K; which could be due to the
decrease in photoelectron heating from reduced photoionization.
Nanosat Formation Flying Design for SNIPE Mission
Authors: Kang Seokju , Song Youngbum , Park Sang-Young
Published: May 2023

This study designs and analyzes satellite formation flying concepts for the Small
scale magNetospheric and Ionospheric Plasma Experiments (SNIPE) mission, that will
observe the near-Earth space environment using four nanosats. To meet the requirements
to achieve the scientific objectives of the SNIPE mission, three formation flying
concepts are analyzed: a crossshape formation, a square-shape formation, and a
cross-track formation. Of the three formation flying scenarios, the crosstrack formation
scenario is selected as the final scenario for the SNIPE mission. The result of this
study suggests a relative orbit control scenario for formation maintenance and
reconfiguration, and the initial relative orbits of the four nanosats meeting the
formation requirements and thrust limitations of the SNIPE mission. The formation flying
scenario is validated by calculating the accumulated total thrust required for the four
nanosats. If the cross-track formation scenario presented in this study is applied to
the SNIPE mission, it is expected that the mission will be successfully accomplished.
Observations of the Polar Ionosphere by the Vertical Incidence Pulsed Ionospheric
Radar at Jang Bogo Station, Antarctica
Authors: Ham Young-Bae , Jee Geonhwa , Lee Changsup , Kwon Hyuk-Jin , Kim Jeong-Han , Zabotin Nikolay , Bullett Terence
Published: May 2023

Korea Polar Research Institute (KOPRI) installed an ionospheric sounding radar
system called Vertical Incidence Pulsed Ionospheric Radar (VIPIR) at Jang Bogo Station
(JBS) in 2015 in order to routinely monitor the state of the ionosphere in the auroral
oval and polar cap regions. Since 2017, after two-year test operation, it has been
continuously operated to produce various ionospheric parameters. In this article, we
will introduce the characteristics of the JBS-VIPIR observations and possible
applications of the data for the study on the polar ionosphere. The JBS-VIPIR utilizes a
log periodic transmit antenna that transmits 0.5–25 MHz radio waves, and a receiving
array of 8 dipole antennas. It is operated in the Dynasonde B-mode pulse scheme and
utilizes the 3-D inversion program, called NeXtYZ, for the data acquisition and
processing, instead of the conventional 1-D inversion procedure as used in the most of
digisonde observations. The JBS-VIPIR outputs include the height profiles of the
electron density, ionospheric tilts, and ion drifts with a 2-minute temporal resolution
in the bottomside ionosphere. With these observations, possible research applications
will be briefly described in combination with other observations for the aurora, the
neutral atmosphere and the magnetosphere simultaneously conducted at JBS.
Linear Instability and Saturation Characteristics of Magnetosonic Waves along the
Magnetic Field Line
Authors: Min Kyungguk , Liu Kaijun
Published: May 2023

Equatorial noise, also known magnetosonic waves (MSWs), are one of the frequently
observed plasma waves in Earth’s inner magnetosphere. Observations have shown that wave
amplitudes maximize at the magnetic equator with a narrow extent in their latitudinal
distribution. It has been understood that waves are generated from an equatorial source
region and confined within a few degrees magnetic latitude. The present study
investigates whether the MSW instability and saturation amplitudes maximize at the
equator, given an energetic proton ring-like distribution derived from an observed wave
event, and using linear instability analysis and particle-in-cell simulations with the
plasma conditions at different latitudes along the dipole magnetic field line. The
results show that waves initially grow fastest (i.e., with the largest growth rate) at
high latitude (20°–25°), but consistent with observations, their saturation amplitudes
maximize within ±10° latitude. On the other hand, the slope of the saturation amplitudes
versus latitude revealed in the present study is not as steep as what the previous
statistical observation results suggest. This may be indicative of some other factors
not considered in the present analyses at play, such as background magnetic field and
plasma inhomogeneities and the propagation effect.
Development of Kinematic Ephemeris Generator for Korea Pathfinder Lunar Orbiter
(KPLO)
Authors: Song Min-Sup , Park Sang-Young , Kim Youngkwang , Yim Jo Ryeong
Published: May 2023

This paper presents a kinematic ephemeris generator for Korea Pathfinder Lunar
Orbiter (KPLO) and its performance test results. The kinematic ephemeris generator
consists of a ground ephemeris compressor and an onboard ephemeris calculator. The
ground ephemeris compressor has to compress desired orbit propagation data by using an
interpolation method in a ground system. The onboard ephemeris calculator can generate
spacecraft ephemeris and the Sun/Moon ephemeris in onboard computer of the KPLO. Among
many interpolation methods, polynomial interpolation with uniform node, Chebyshev
interpolation, Hermite interpolation are tested for their performances. As a result of
the test, it is shown that all the methods have some cases that meet requirements but
there are some performance differences. It is also confirmed that, the Chebyshev
interpolation shows better performance than other methods for spacecraft ephemeris
generation, and the polynomial interpolation with uniform nodes yields good performance
for the Sun/Moon ephemeris generation. Based on these results, a Kinematic ephemeris
generator is developed for the KPLO mission. Then, the developed ephemeris generator can
find an approximating function using interpolation method considering the size and
accuracy of the data to be transmitted.
Ground Tracking Support Condition Effect on Orbit Determination for Korea Pathfinder Lunar Orbiter (KPLO) in Lunar Orbit
Authors: Kim Young-Rok , Song Young-Joo , Park Jae-ik , Lee Donghun , Bae Jonghee , Hong SeungBum , Kim Dae-Kwan , Lee Sang-Ryool
Published: May 2023

The ground tracking support is a critical factor for the navigation performance of spacecraft orbiting around the Moon. Because of the tracking limit of antennas, only a small number of facilities can support lunar missions. Therefore, case studies for various ground tracking support conditions are needed for lunar missions on the stage of preliminary mission analysis. This study analyzes the ground supporting condition effect on orbit determination (OD) of Korea Pathfinder Lunar Orbiter (KPLO) in the lunar orbit. For the assumption of ground support conditions, daily tracking frequency, cut-off angle for low elevation, tracking measurement accuracy, and tracking failure situations were considered. Two antennas of deep space network (DSN) and Korea Deep Space Antenna (KDSA) are utilized for various tracking conditions configuration. For the investigation of the daily tracking frequency effect, three cases (full support, DSN 4 pass/day and KDSA 4 pass/day, and DSN 2 pass/day and KDSA 2 pass/day) are prepared. For the elevation cut-off angle effect, two situations, which are 5 deg and 10 deg, are assumed. Three cases (0%, 30%, and 50% of degradation) were considered for the tracking measurement accuracy effect. Three cases such as no missing, 1-day KDSA missing, and 2-day KDSA missing are assumed for tracking failure effect. For OD, a sequential estimation algorithm was used, and for the OD performance evaluation, position uncertainty, position differences between true and estimated orbits, and orbit overlap precision according to various ground supporting conditions were investigated. Orbit prediction accuracy variations due to ground tracking conditions were also demonstrated. This study provides a guideline for selecting ground tracking support levels and preparing a backup plan for the KPLO lunar mission phase.
Geostationary Satellite Station Keeping Robustness to Loss of Ground
Control
Authors: Woo Hyung Je , Buckwalter Bjorn
Published: May 2023

For the vast majority of geostationary satellites currently in orbit, station
keeping activities including orbit determination and maneuver planning and execution are
ground-directed and dependent on the availability of ground-based satellite control
personnel and facilities. However, a requirement linked to satellite autonomy and
survivability in cases of interrupted ground support is often one of the stipulated
provisions on the satellite platform design. It is especially important for a
geostationary military-purposed satellite to remain within its designated orbital
window, in order to provide reliable uninterrupted telecommunications services, in the
absence of ground-based resources due to warfare or other disasters. In this paper we
investigate factors affecting the robustness of a geostationary satellite’s orbit in
terms of the maximum duration the satellite’s station keeping window can be maintained
without ground intervention. By comparing simulations of orbit evolution, given
different initial conditions and operations strategies, a variation of parameters study
has been performed and we have analyzed which factors the duration is most sensitive to.
This also provides valuable insights into which factors may be worth controlling by a
military or civilian geostationary satellite operator. Our simulations show that the
most beneficial factor for maximizing the time a satellite will remain in the station
keeping window is the operational practice of pre-emptively loading East-West station
keeping maneuvers for automatic execution on board the satellite should ground control
capability be lost. The second most beneficial factor is using short station keeping
maneuver cycle durations.
A Preliminary Impulsive Trajectory Design for (99942) Apophis Rendezvous
Mission
Authors: Kim Pureum , Park Sang-Young , Cho Sungki , Jo Jung Hyun
Published: May 2023

In this study, a preliminary trajectory design is conducted for a conceptual
spacecraft mission to a near-Earth asteroid (NEA) (99942) Apophis, which is expected to
pass by Earth merely 32,000 km from the Earth’s surface in 2029. This close approach
event will provide us with a unique opportunity to study changes induced in asteroids
during close approaches to massive bodies, as well as the general properties of NEAs.
The conceptual mission is set to arrive at and rendezvous with Apophis in 2028 for an
advanced study of the asteroid, and some near-optimal (in terms of fuel consumption)
trajectories under this mission architecture are to be investigated using a global
optimization algorithm called monotonic basin hopping. It is shown that trajectories
with a single swing-by from Venus or Earth, or even simpler ones without gravity assist,
are the most feasible. In addition, launch opportunities in 2029 yield another possible
strategy of leaving Earth around the 2029 close approach event and simply following the
asteroid thereafter, which may be an alternative fuel-efficient option that can be
adopted if advanced studies of Apophis are not required.
The First Report on the Afternoon E -Region Plasma Density Irregularities in Middle
Latitude
Authors: Yang Tae-Yong , Kwak Young-Sil , Lee Jaewook , Park Jaeheung , Choi Seonghwan
Published: May 2023

We report, for the first time, the afternoon (i.e., from noon to sunset time)
observations of the northern mid-latitude E-region field-aligned irregularities (FAIs)
made by the very high frequency (VHF) coherent backscatter radar operated continuously
since 29 December 2009 at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South
Korea. We present the statistical characteristics of the mid-latitude afternoon E-region
FAIs based on the continuous radar observations. Echo signal-to-noise ratio (SNR) of the
afternoon E-region FAIs is found to be as high as 35 dB, mostly occurring around 100–135
km altitudes. Most spectral widths of the afternoon echoes are close to zero, indicating
that the irregularities during the afternoon time are not related to turbulent plasma
motions. The occurrence of afternoon E-regional FAI is observed with significant
seasonal variation, with a maximum in summer and a minimum in winter. Furthermore, to
investigate the afternoon E-region FAIs- Sporadic E (Es) relationship, the FAIs have
also been compared with Es parameters based on observations made from an ionosonde
located at Icheon (37.14°N, 127.54°E, 27.7°N dip latitude), which is 100 km north of
Daejeon. The virtual height of Es (h’Es) is mainly in the height range of 105 km to 110
km, which is 5 km to 10 km greater than the bottom of the FAI. There is no relationship
between the FAI SNR and the highest frequencies (ftEs) (or blanket frequencies (fbEs)).
SNR of FAIs, however, is found to be related well with (ftEs–fbEs).
Preliminary Analysis on Launch Opportunities for Sun-Earth Lagrange Points Mission from NARO Space Center
Authors: Song Young-Joo , Lee Donghun
Published: May 2023

In this work, preliminary launch opportunities from NARO Space Center to the Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points, L1 and L2 points are selected as suitable candidates for, respectively, solar and astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting problem is formulated regarding the location of NARO Space Center and relevant Target Interface Point (TIP) for each different launch date is derived including launch injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more than one year of mission orbit around the Lagrange points, is also derived as an example. Even the current work has been made under many assumptions as there are no specific mission goals currently defined yet, so results from the current work could be a good starting point to extend diversities of future Korean deep-space missions.
Investigation of the Jets of the Blazar 3C 279 with Korean VLBI Network (KVN)
22–129 GHz Observations
Authors: Yoo Sungmin , Lee Sang-Sung , Kim Sang-Hyun , An Hongjun
Published: May 2023

We present analysis results of Korean VLBI Network (KVN) four-band data for the
highly variable blazar 3C 279. We measured the 22, 43, 86, and 129 GHz flux densities
and spectral indices of the source using contemporaneous data taken over 5.6 years. We
used the discrete correlation function to investigate correlations between the radio
emission properties and those measured in the optical (2 × 1014 – 1.5 × 1015 Hz), X-ray
(0.3–10 keV), and gamma-ray (0.1–300 GeV) bands. We found a significant correlation
between the radio spectral index and gamma-ray flux without a time delay and interpreted
the correlation using an extended jet scenario for blazar emission.
Observations of the Aurora by Visible All-Sky Camera at Jang Bogo Station,
Antarctica
Authors: Jee Geonhwa , Ham Young-Bae , Choi Yoonseung , Kim Eunsol , Lee Changsup , Kwon Hyuckjin , Trondsen Trond S. , Kim Ji Eun , Kim Jeong-Han
Published: May 2023

The auroral observation has been started at Jang Bogo Station (JBS), Antarctica
by using a visible All-sky camera (v-ASC) in 2018 to routinely monitor the aurora in
association with the simultaneous observations of the ionosphere, thermosphere and
magnetosphere at the station. In this article, the auroral observations are introduced
with the analysis procedure to recognize the aurora from the v-ASC image data and to
compute the auroral occurrences and the initial results on their spatial and temporal
distributions are presented. The auroral occurrences are mostly confined to the northern
horizon in the evening sector and extend to the zenith from the northwest to cover
almost the entire sky disk over JBS at around 08 MLT (magnetic local time; 03 LT) and
then retract to the northeast in the morning sector. At near the magnetic local noon,
the occurrences are horizontally distributed in the northern sky disk, which shows the
auroral occurrences in the cusp region. The results of the auroral occurrences indicate
that JBS is located most of the time in the polar cap near the poleward boundary of the
auroral oval in the nightside and approaches closer to the oval in the morning sector.
At around 08 MLT (03 LT), JBS is located within the auroral oval and then moves away
from it, finally being located in the cusp region at the magnetic local noon, which
indicates that the location of JBS turns out to be ideal to investigate the
variabilities of the poleward boundary of the auroral oval from long-term observations
of the auroral occurrences. The future plan for the ground auroral observations near JBS
is presented.
Development of a New Pressure-Sinkage Model for Rover Wheel-Lunar Soil Interaction
based on Dimensional Analysis and Bevameter Tests
Authors: Lim Yujin , Le Viet Dinh , Bahati Pierre Anthyme
Published: May 2023

A rover is a planetary surface exploration device designed to move across the
ground on a planet or a planetary-like body. Exploration rovers are increasingly
becoming a vital part of the search for scientific evidence and discoveries on a
planetary satellite of the Sun, such as the Moon or Mars. Reliable behavior and
predictable locomotion of a rover is important. Understanding soil behavior and its
interaction with rover wheels—the terramechanics—is of great importance in rover
exploration performance. Up to now, many researchers have adopted Bekker’s semiempirical
model to predict rover wheelsoil interaction, which is based on the assumption that soil
is deformable when a pressure is applied to it. Despite this basic assumption of the
model, the pressure-sinkage relation is not fully understood, and it continues to
present challenges for rover designers. This article presents a new pressure-sinkage
model based on dimensional analysis (DA) and results of bevameter tests. DA was applied
to the test results in order to propose a new pressure-sinkage model by reducing
physical quantitative parameters. As part of the work, a new bevameter was designed and
built so that it could be successfully used to obtain a proper pressure-sinkage relation
of Korean Lunar Soil Simulant (KLS-1). The new pressure-sinkage model was constructed by
using three different sizes of flat plate diameters of the bevameter. The newly proposed
model was compared successfully with other models for validation purposes.
Empirical Modeling of the Global Distribution of Magnetosonic Waves with Ambient
Plasma Environment using Van Allen Probes
Authors: Kim Kyung-Chan
Published: May 2023

It is suggested that magnetosonic waves (also known as equatorial noise) can
scatter radiation belt electrons in the Earth’s magnetosphere. Therefore, it is
important to understand the global distribution of these waves between the proton
cyclotron frequency and the lower hybrid resonance frequency. In this study, we
developed an empirical model for estimating the global distribution of magnetosonic wave
amplitudes and wave normal angles. The model is based on the entire mission period
(approximately 2012–2019) of observations of Van Allen Probes A and B as a function of
the distance from the Earth (denoted by L*), magnetic local time (MLT), magnetic
latitude (λ), and geomagnetic activity (denoted by the Kp index). In previous studies
the wave distribution inside and outside the plasmasphere were separately investigated
and modeled. Our model, on the other hand, identifies the wave distribution along with
the ambient plasma environment—defined by the ratio of the plasma frequency (fpe) to the
electron cyclotron frequency (fce)—without separately determining the wave distribution
according to the plasmapause location. The model results show that, as Kp increases, the
dayside wave amplitude in the equatorial region intensifies. It thereby propagates the
intense region towards the wider MLT and inward to L* < 4. In contrast, the fpe/fce
ratio decreases with increasing Kp for all regions. Nevertheless, the decreasing aspect
differs between regions above and below L* = 4. This finding implies that the particle
energy and pitch angle that magnetosonic waves can effectively scatter vary depending on
the locations and geomagnetic activity. Our model agrees with the statistically observed
wave distribution and ambient plasma environment with a coefficient of determination of
> 0.9. The model is valid in all MLTs, 2 ≤ L* < 6, |λ| < 20°, and Kp ≤ 6.
Electromagnetic Electron-Cyclotron Wave for Ring Distribution with Alternating
Current (AC) Electric Field in Saturn Magnetosphere
Authors: Haridas Annex Edappattu , Kanwar Shefali , Pandey Rama Shankar
Published: May 2023

During their respective missions, the spacecraft Voyager and Cassini measured
several Saturn magnetosphere parameters at different radial distances. As a result of
information gathered throughout the journey, Voyager 1 discovered hot and cold electron
distribution components, number density, and energy in the 6–18 Rs range. Observations
made by Voyager of intensity fluctuations in the 20–30 keV range show electrons are
situated in the resonance spectrum’s high energy tail. Plasma waves in the magnetosphere
can be used to locate Saturn’s inner magnetosphere’s plasma clusters, which are
controlled by Saturn’s spin. Electromagnetic electron cyclotron (EMEC) wave ring
distribution function has been investigated. Kinetic and linear approaches have been
used to study electromagnetic cyclotron (EMEC) wave propagation. EMEC waves’ stability
can be assessed by analyzing the dispersion relation’s effect on the ring distribution
function. The primary goal of this study is to determine the impact of the magnetosphere
parameters which is observed by Cassini. The magnetosphere of Saturn has also been
observed. When the plasma parameters are increased as the distribution index, the
growth/damping rate increases until the magnetic field model affects the magnetic field
at equator, as can be seen in the graphs. We discuss the outputs of our model in the
context of measurements made in situ by the Cassini spacecraft.
Interaction of Ion Cyclotron Electromagnetic Wave with Energetic Particles in the
Existence of Alternating Electric Field Using Ring Distribution
Authors: Shukla Kumari Neeta , Kumari Jyoti , Pandey Rama Shankar
Published: May 2023

The elements that impact the dynamics and collaborations of waves and particles
in the magnetosphere of planets have been considered here. Saturn’s internal
magnetosphere is determined by substantiated instabilities and discovered to be an
exceptional zone of wave activity. Interchanged instability is found to be one of the
responsible events in view of temperature anisotropy and energization processes of
magnetospheric species. The generated active ions alongside electrons that constitute
the populations of highly magnetized planets like Saturn’s ring electron current are
taken into consideration in the current framework. The previous and similar method of
characteristics and the perturbed distribution function have been used to derive
dispersion relation. In incorporating this investigation, the characteristics of
electromagnetic ion cyclotron wave (EMIC) waves are determined by the composition of
ions in plasmas through which the waves propagate. The effect of ring distribution
illustrates non-monotonous description on growth rate (GR) depending upon plasma
parameters picked out. Observations made by Cassini found appropriate for modern study,
have been applied to the Kronian magnetosphere. Using Maxwellian ring distribution
function of ions and detailed mathematical formulation, an expression for dispersion
relation as well as GR and real frequency (RF) are evaluated. Analysis of plasma
parameters shows that, proliferating EMIC waves are not developed much when propagation
is parallelly aligned with magnetosphere as compared to waves propagating in oblique
direction. GR for the oblique case, is influenced by temperature anisotropy as well as
by alternating current (AC) frequency, whereas it is much affected only by AC frequency
for parallel propagating waves.
Climatology of Equatorial Plasma Bubbles in Ionospheric Connection
Explorer/Far-UltraViolet (ICON/FUV) Limb Images
Authors: Park Jaeheung , Mende Stephen B. , Eastes Richard W. , Frey Harald U.
Published: May 2023

The Far-UltraViolet (FUV) imager onboard the Ionospheric Connection Explorer
(ICON) spacecraft provides two-dimensional limb images of oxygen airglow in the
nightside low-latitude ionosphere that are used to determine the oxygen ion density. As
yet, no FUV limb imager has been used for climatological analyses of Equatorial Plasma
Bubbles (EPBs). To examine the potential of ICON/FUV for this purpose, we statistically
investigate small-scale (~180 km) fluctuations of oxygen ion density in its limb images.
The seasonal-longitudinal variations of the fluctuation level reasonably conform to the
EPB statistics in existing literature. To further validate the ICON/FUV data quality, we
also inspect climatology of the ambient (unfiltered) nightside oxygen ion density. The
ambient density exhibits (1) the well-known zonal wavenumber-4 signatures in the
Equatorial Ionization Anomaly (EIA) and (2) off-equatorial enhancement above the
Caribbean, both of which agree with previous studies. Merits of ICON/FUV observations
over other conventional data sets are discussed in this paper. Furthermore, we suggest
possible directions of future work, e.g., synergy between ICON/FUV and the Global-scale
Observations of the Limb and Disk (GOLD) mission.
On the Influence of the Moment of Inertia of Gas on the Galactic Rotation
Curves
Authors: Portnov Yuriy A.
Published: May 2023

There are two models that explain the rotation curves of galaxies: dark matter,
which gives the missing contribution to the gravitational potential of the standard
theory of gravity, and modified theories of gravity, according to which the
gravitational potential is created by ordinary visible mass. Both models have some
disadvantages. The article offers a new look at the problem of galactic rotation curves.
The author suggests that the moment of inertia creates an additional gravitational
potential along with the mass. The numerical simulation carried out on the example of
fourteen galaxies confirms the validity of such an assumption. This approach makes it
possible to explain the constancy of gas velocities outside the galactic disk without
involving the hypothesis of the existence of dark matter. At the same time, the proposed
approach lacks the disadvantages of modified theories of gravity, where the
gravitational potential is created only by the mass of visible matter.
Analysis of the Tsyganenko Magnetic Field Model Accuracy during Geomagnetic Storm
Times Using the GOES Data
Authors: Song Seok-Min , Min Kyungguk
Published: May 2023

Because of the small number of spacecraft available in the Earth’s magnetosphere
at any given time, it is not possible to obtain direct measurements of the fundamental
quantities, such as the magnetic field and plasma density, with a spatial coverage
necessary for studying, global magnetospheric phenomena. In such cases, empirical as
well as physics-based models are proven to be extremely valuable. This requires not only
having high fidelity and high accuracy models, but also knowing the weakness and
strength of such models. In this study, we assess the accuracy of the widely used
Tsyganenko magnetic field models, T96, T01, and T04, by comparing the calculated
magnetic field with the ones measured in-situ by the GOES satellites during
geomagnetically disturbed times. We first set the baseline accuracy of the models from a
data-model comparison during the intervals of geomagnetically quiet times. During quiet
times, we find that all three models exhibit a systematic error of about 10% in the
magnetic field magnitude, while the error in the field vector direction is on average
less than 1%. We then assess the model accuracy by a data-model comparison during twelve
geomagnetic storm events. We find that the errors in both the magnitude and the
direction are well maintained at the quiet-time level throughout the storm phase, except
during the main phase of the storms in which the largest error can reach 15% on average,
and exceed well over 70% in the worst case. Interestingly, the largest error occurs not
at the Dst minimum but 2–3 hours before the minimum. Finally, the T96 model has
consistently underperformed compared to the other models, likely due to the lack of
computation for the effects of ring current. However, the T96 and T01 models are
accurate enough for most of the time except for highly disturbed periods.
PENENTUAN PENAMPUNGAN KORBAN BANJIR BERBASIS SISTEM INFORMASI GEOGRAFIS
Authors: Zulfikri Ahmad , Nugroho Adhi Santoso  , Rifki Dwi Kurniawan
Published: May 2023

Banjir menjadi sebuah masalah tahunan yang terjadi dibeberapa wilayah di Indonesia. Evakuasi korban  banjir sangat diperlukan dalam rangka meminimalisir adanya korban-korban yang berjatuhan, oleh karena itu perlu dilakukan penentuan terhadap penampungan korban banjir. Tujuan penelitian ini yakni untuk menentukan penampungan korban banji berbasis sistem informasi geografis. Metode yang dipergunakan dalam penelitian ini yaitu mengacu pada penelitian kualitatif dengan studi literatur. Hasil yang didapatkan diantaranya dalam menentukan terhadap dua tahapan yaitu menganalisa determinasi zona banjir (melakukan analisa peta rupa bumi, citra landsat, data curah hujan, dan pembuatan peta buffer sungai) dan menganalisa data (analisa keruangan dan atribut). Simpulan yang dapat diambil dari penelitian ini bahwa penentuan penampungan korban banjir dengan mempergunakan Sistem Informasi Geografis mampu dilakukan dengan pembangunan database dan analisa data, dimulai dengan analisa determinan zona banjir, dan analisa data. Data tersebut yang menjadi acuan untuk menentukan arah yang efektif pada jalur evakuasi bencana banjir pada suatu wilayah tertentu.
EVALUASI USABILITY PORTAL AKADEMIK MAHASISWA MENGGUNAKAN METODE THINK ALOUD (STUDI KASUS: POLITEKNIK KEUANGAN NEGARA STAN)
Authors: Maharani Azzahra Cantika , Retno Indah Rokhmawati  , Yusi Tyroni Mursityo
Published: May 2023

PKN STAN merupakan pendidikan tinggi kedinasan di bawah Badan Pendidikan dan Pelatihan Keuangan (BPPK), Kementerian Keuangan Republik Indonesia, yang menyelenggarakan pendidikan Program Studi Diploma bidang keuangan negara. Untuk menunjang kegiatan akademik, digunakan portal akademik sebagai alat utamanya. Namun, terdapat berbagai masalah pada portal akademik mahasiswa sehingga mengganggu kegiatan akademik. Dari permasalahan tersebut dilakukan evaluasi usability menggunakan metode think aloud untuk mengetahui permasalahan. Dari permasalahan yang ditemukan, diberikan rekomendasi perbaikan antarmuka pengguna yang akan dievaluasi kembali untuk mengetahui perbandingan hasil evaluasi. Penelitian ini menghasilkan data kualitatif yaitu feedback pengguna dan data kuantitatif berupa penilaian tiga aspek usability yaitu efektivitas, efisiensi, dan kepuasan. Hasil evaluasi perbandingan kualitatif menunjukkan perbaikan yang diberikan mendapat lebih banyak respons positif namun masih terdapat respons negatif seperti perlunya penyesuaian terhadap perbaikan dan komponen yang digunakan. Untuk hasil kuantitatif, didapatkan peningkatan tingkat efektivitas sebesar 9,5%, tingkat efisiensi meningkat sebesar 2%, dan nilai rata-rata kepuasan pengguna naik sebesar 21,4.
Global Neurosurgery Assimilation into the Global Surgery Movement
Authors: Ham Edward I , Dada Olaoluwa Ezekiel , Abdi Hodan , Veerappan Vigneshwar Raj , Park Kee B.
Published: May 2023

In 2019, the World Federation of Neurosurgical Societies (WFNS) created the Global Neurosurgery Committee (GNC). The GNC’s Global Action Plan is comprised of 5 objectives: 1) amplifying access to neurosurgical care, 2) aligning global neurosurgical activity, 3) advancing relevant research, especially from low-and-middle-income country (LMIC) authors, 4) assimilating neurosurgical capacity building into surgical systems planning and 5) advocating for (neuro)surgical care within universal health coverage. The goal to assimilate global neurosurgery (GNS) into surgical system planning is further divided into 2 specific goals for 2021: 1) Increasing participation of neurosurgeons in >50% of efforts to strengthen national surgical systems, and 2) increasing the rate of participation by neurosurgeons in major global surgery conferences by >20%. In this paper, the importance of the assimilate objectives will be reviewed, current progress towards the first Assimilate objective will be highlighted, and next steps will be discussed.
The Role of Neurosurgeons in Policy Development: Addressing Unmet Neurosurgical Needs in Low-and-Middle Income Countries
Authors: Ham Edward , Park Kee , Egnor Michael
Published: May 2023

Introduction: Global Neurosurgical (GNS) publications can be classified into two broad categories: 1) clinical research and 2) public health research. To date, most papers and manuscripts have been clinical in nature. However, over the past 5 years, the focus of GNS manuscripts have changed dramatically. A recent scoping review identified public health-oriented GNS manuscripts from 1999 to 2019 and categorized them by the WHO’s six Health System domains (service delivery, workforce, infrastructure, financing, information management, and governance). The objectives of this follow-up study include: 1) updating the literature search done in the scoping review and 2) discussing the importance of comprehensive policy recommendations.

Methods: We searched three databases – PubMed/MEDLINE, CINAHL, and EMBASE – for GNS literature published from June 2019 (the end of previous search date) to December 2020. Afterwards, a title & abstract screening was conducted.

Results: A total of 246 references were found across the three aforementioned databases. After the title & abstract screening, 68 GNS manuscripts were identified. Although a full-text review was not conducted, this cursory search supports the notion that the GNS community is now shifting towards a more holistic, health systems-oriented approach.

One limitation to this search method is the exclusion of commentaries and policy briefs that discussed governance within GNS. For example, the study excluded the Comprehensive Policy Recommendations that have been released by the Program for Global Surgery and Social Change (PGSSC). The first set of recommendations were about head and spine injuries. The second set of recommendations – published at the end of 2021 – focused on policy related to the management of Spina Bifida and Hydrocephalus.

Discussion: The Comprehensive Policy Recommendations clearly highlight how neurosurgeons can influence policy development and implementation. While these publications are a step forward, it is not enough. Moving ahead, the GNS community should: 1) widely disseminate the document to all, 2) selectively distribute the document to Ministries of Health, and 3) conduct more policy-focused research. To adequately address the unmet neurosurgical needs in LMICs, collaboration is paramount. It is time for neurosurgeons to think beyond the operating room.
Advancing Relevant Research
Authors: Abdi Hodan , Boyke Andre E. , Ham Edward , Hamzah Radzi , Negida Ahmed , Rolle Myron , Ammar Adam , Park Kee B.
Published: May 2023

The Global Neurosurgery Committee (GNC) of the World Federation of Neurosurgical Societies (WFNS) launched the Global Action Plan during the 2016 Bogota Declaration on Global Neurosurgery in Colombia in order to coordinate efforts and bring neurosurgeons around the world to address unmet neurosurgical care. The Global Action Plan contains five objectives: Amplify, Align, Advance, Assimilate and Advocate for neurosurgical care.  In this paper, we present the goals and the work of the Advance team. The goal of the Advance objective was to “A. Map research output by region and themes, B. Establish one or more Global Neurosurgery research grant and/or award mechanisms, C. Advocate for Global Neurosurgery category/sections in major neurosurgery journals (3 or more by 2021), D. Establish funding mechanisms for training in future leaders in the public health practice of Global Neurosurgery (2 or more by 2021), E. Inclusion of Global Neurosurgery Sessions in major neurosurgery meetings (>75% by 2021), F. Establish a mentoring relationship between editorial board members from HIC and LMICs (>1 by 2021), and G. Establish a mentoring relationship between authors from HIC and LMICs (>1 by 2021).
Working Out of the Silo of Global Neurosurgery
Authors: Hamzah Radzi , Shlobin Nathan A. , Ip Ho Kei Yuki , Ham Edward , Negida Ahmed , Ammar Adam , Park Kee B.
Published: May 2023

The field of global surgery has gained attention since the publication of the Lancet Commission landmark report in 2015. The authors estimated that 5 billion people worldwide do not have access to safe, affordable surgical and anesthesia services. The paper “Global Neurosurgery: The Unmet Need,” published in 2016, launched the modern global neurosurgery era by advocating for the system-level thinking and programs required to address limited neurosurgical care in low-resource settings.

 

At present, many individuals, academic institutions, governmental agencies, and nongovernmental organizations (NGOs) are involved in the global neurosurgery movement. These include the Program in Global Surgery and Social Change at Harvard Medical School, Duke Global Neurology and Neurosurgery, Weill Cornell Tanzania Neurosurgery Project, CURE Children’s Hospital of Uganda, and the Virtue Foundation in Mongolia. Nonetheless, as global neurosurgery efforts continue to expand, it is essential to align global neurosurgery activity in order to prevent duplication of effort.

 

In 2019, the World Federation of Neurosurgical Societies (WFNS) established the Global Neurosurgery Committee (GNC) to promote access to safe, affordable, and timely neurosurgical care worldwide. The GNC initially included five primary objectives – Amplify, Align, Advance, Assimilate, and Advocate – with the sixth objective, Communication, added in 2021. In this manuscript, we provide an update on the Align objective team.