• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.81.2-81.2
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• 2019

We develop an image-to-image translation model, which is a popular deep learning method based on conditional Generative Adversarial Networks (cGANs), to generate solar magnetograms and EUV images from sunspot drawings. For this, we train the model using pairs of sunspot drawings from Mount Wilson Observatory (MWO) and their corresponding SDO/HMI magnetograms and SDO/AIA EUV images (512 by 512) from January 2012 to September 2014. We test the model by comparing pairs of actual SDO images (magnetogram and EUV images) and the corresponding AI-generated ones from October to December in 2014. Our results show that bipolar structures and coronal loop structures of AI-generated images are consistent with those of the original ones. We find that their unsigned magnetic fluxes well correlate with those of the original ones with a good correlation coefficient of 0.86. We also obtain pixel-to-pixel correlations EUV images and AI-generated ones. The average correlations of 92 test samples for several SDO lines are very good: 0.88 for AIA 211, 0.87 for AIA 1600 and 0.93 for AIA 1700. These facts imply that AI-generated EUV images quite similar to AIA ones. Applying this model to the Galileo sunspot drawings in 1612, we generate HMI-like magnetograms and AIA-like EUV images of the sunspots. This application will be used to generate solar images using historical sunspot drawings.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.113.2-113.2
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• 2012

An innovative solar observing satellite, Hinode, has successfully observed the detailed evolution of a rapidly developing emerging flux region from the beginning of its appearance at the solar surface. The high spatial and temporal resolution provided by the satellite enables to capture the prominent dynamic processes such as the rotational motion of a polarity region with intense magnetic flux which is reminiscent of a cyclone on the Earth, and a running wave that spreads ahead of this rotating polarity region. This 'solar cyclone' is, on the other hand, generated differently from terrestrial cyclones, and a possible generating mechanism for it is demonstrated with a three-dimensional magnetohydrodynamic simulation of a twisted magnetic flux tube emerging from the solar interior into the solar atmosphere. The simulation shows that the rotational motion is caused by a strong downflow of plasma along the twisted field lines that form a helical pillar standing upright on the Sun.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.52.1-52.1
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• 2019

The Helioseismic and Magnetic Imager (HMI) is the instrument of Solar Dynamics Observatory (SDO) to study the magnetic field and oscillation at the solar surface. The HMI image is not enough to analyze very small magnetic features on solar surface since it has a spatial resolution of one arcsec. Super resolution is a technique that enhances the resolution of a low resolution image. In this study, we use a method for enhancing the solar image resolution using a Deep-learning model which generates a high resolution HMI image from a low resolution HMI image (4 by 4 binning). Deep learning networks try to find the hidden equation between low resolution image and high resolution image from given input and the corresponding output image. In this study, we trained a model based on a very deep residual channel attention networks (RCAN) with HMI images in 2014 and test it with HMI images in 2015. We find that the model achieves high quality results in view of both visual and measures: 31.40 peak signal-to-noise ratio(PSNR), Correlation Coefficient (0.96), Root mean square error (RMSE) is 0.004. This result is much better than the conventional bi-cubic interpolation. We will apply this model to full-resolution SDO/HMI and GST magnetograms.

• The Journal of Sustainable Design and Educational Environment Research
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• v.18 no.4
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• pp.33-43
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• 2019

This study was to research and analyze the concept of school space innovation to aim at the importance of user educational value. The purpose of this study is to analyze the needs of students, teachers, or consumers connected with the educational autonomous innovative curriculum and various school-government educational activities and suggest the ways to link school space innovation to the best possible reflection for demander-centered or the demander needs To this end, the basic concepts of the autonomous education and school space innovation were reviewed, and the literature survey on the revised education curriculum in 2015 and educational autonomous innovation curriculum at the national level, educational goals and basic value-added awareness of the curriculum. The purpose was to research the perception of students and teachers through the survey and analysis of basic values of education, the functions of school education, the direction of school environment and space spatial composition, and school space.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.99.1-99.1
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• 2014

달은 global magnetic fields가 존재하지 않으나, 달 표면에 국지적으로 자기장이 존재하며 이러한 현상의 원인은 계속 연구중이다. 달의 자기이상 현상이 나타나는 지역 중 광학적으로 밝고 어두운 패턴이 관측되는 지역을 Swirl이라한다. Mare Crisium ($17.18^{\circ}N$, $59.1^{\circ}E$)은 표면에 2개의 자기이상 지역과 광학적으로 밝은 지역들이 존재하지만, Swirl로 잘 알려진 Reiner Gamma와 같은 지역의 광학적 밝기와 패턴의 차이가 있다. 이를 위해 본 연구에서는 Lunar Prospector (LP) 위성의 magnetometer (MAG) 자료를 이용하여 자기장 분포에 관한 연구 및 Clementine 위성의 UV/VIS 영상자료를 이용하여 광학적 특성 연구를 진행하였다. LP의 MAG 자료는 Mare Cirisium지역의 22.3 km 고도에서 관측된 744개의 자료를 활용하였으며, Clementine의 영상자료는 750 nm, 950 nm의 반사도에 따른 Optical Maturity (OMAT)를 활용하였다. Mare Crisium의 북쪽지역은 자기이상 현상과 OMAT의 고유특성이 동시에 나타나며 이는 swirl과 유사하다. 특히, Mare Cirisum서쪽에 있는 Proclus crater 잔해 일부가 Mare Crisium의 북쪽지역까지 퍼져있어 이와 관련하여 자기장 존재여부에 따른 광학적 특성의 차이점을 조사하였다. 본 논문에서는 Mare Crisium 지역의 Swirl 진위여부를 추론하며, 본 논문에서 이용한 방법의 유용성에 대하여 검증하고자 한다.

• Bulletin of the Korean Space Science Society
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• 1999.09a
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• pp.78-78
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• 1999

No Abstract, See Full Text

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.108.2-108.2
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• 2014

과거 달 탐사 미션으로 달에는 global magnetic fields는 존재하지 않고 표면에 국부적으로 자기장이 존재함이 확인되었다. 그러나 이렇게 측정된 자기장 데이터는 일정 고도 (> 20 km) 이상에서 측정되었기 때문에, 지표에 비해 그 세기가 매우 약해 자기장의 형태와 분포를 연구하는데 한계가 있다. 보다 자세한 연구를 위해서는 표면에서부터 다양한 고도에 이르는 위치에서 측정된 자기장 데이터가 필요하며, 이는 달 표토의 자화나 Swirl 형성 메커니즘을 이해하는데 중요한 정보이다. 따라서 본 연구에서는 큐브위성을 이용하여 저궤도부터 지표까지의 자기장을 측정하는 방안을 소개한다. 큐브위성은 달 궤도 모선에서 사출되어 자기이상 지역 표면에 충돌하는 임무를 가진다. 자력계는 모선과 큐브위성에 각각 탑재되어 자기장을 측정하며, 모선으로 부터 사출된 큐브위성은 충돌 직전까지 자기장을 측정하고 모선에 습득한 데이터를 실시간으로 전송한다. 이렇게 측정된 자기장 데이터는 모선의 궤도부터 표면에 이르기까지 여러 고도에서 측정되었기 때문에 자기이상 지역의 자기장 구조를 파악하는데 중요한 자료로 활용할 수 있다. 이에 본 연구에서는 달의 자기이상 지역과 큐브위성 임무 설계에 대하여 기술하였다.

• Journal of Astronomy and Space Sciences
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• v.30 no.1
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• pp.25-32
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• 2013

We statistically investigated the properties of low-latitude Pi2 pulsations using Bohyun (BOH, Mlat = $29.8^{\circ}$, L = 1.35) ground magnetometer data in 2008. For this 1-year interval, 582 Pi2 events were identified when BOH was in the nightside from 1800 to 0600 local times. We found the following Pi2 characteristics. (1) The occurrence distribution of Pi2s is relatively constant in local times. (2) The Pi2 frequency varies in local times. That is, Pi2 pulsations in postmidnight sector had higher frequency than in premidnight sector. (3) Pi2 power in premidnight sector is stronger than in postmidnight sector. (4) Pi2 frequency has positive correlation with solar wind speed and AE index. (5) Pi2 power has not a clear correlation with solar wind parameters. This indicates that Pi2 power is not controlled by external sources. (6) It is found that the most probable-time between Pi2 onsets is ${\Delta}t$ ~ 37.5 min: This is interpreted to be the period between Pi2 pulsations when they occur cyclically. We suggest that ${\Delta}t$ ~ 37.5 min is the occurrence rate of reconnection of open field lines in the tail lobe.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.209-218
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• 2020

This paper describes the initial operations and preliminary results of the Instrument for the study of Stable/Storm-time Space (ISSS) onboard the microsatellite Next Generation Small Satellite-1 (NEXTSat-1), which was launched on December 4, 2018 into a sun-synchronous orbit at an altitude of 575 km with an orbital inclination angle of 97.7°. The spacecraft and the instruments have been working normally, and the results from the observations are in agreement with those from other satellites. Nevertheless, improvement in both the spacecraft/instrument operation and the analysis is suggested to produce more fruitful scientific results from the satellite operations. It is expected that the ISSS observations will become the main mission of the NEXTSat-1 at the end of 2020, when the technological experiments and astronomical observations terminate after two years of operation.

• Journal of The Korean Astronomical Society
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• v.55 no.1
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• pp.11-22
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• 2022

We introduce the Transformable Reflective Telescope (TRT) kit that applies an aluminum profile as a base plate for precise, stable, and lightweight optical system. It has been utilized for optical surface measurements, developing alignment and baffle systems, observing celestial objects, and various educational purposes through Research & Education projects. We upgraded the TRT kit using the aluminum profile and truss and isogrid structures for a high-end optical test device that can be used for prototyping of precision telescopes or satellite optical systems. Thanks to the substantial aluminum profile and lightweight design, mechanical deformation by self-weight is reduced to maximum 67.5 ㎛, which is an acceptable misalignment error compared to its tolerance limits. From the analysis results of non-linear vibration simulations, we have verified that the kit survives in harsh vibration environments. The primary mirror and secondary mirror modules are precisely aligned within 50 ㎛ positioning error using the high accuracy surface finished aluminum profile and optomechanical parts. The cross laser module helps to align the secondary mirror to fine-tune the optical system. The TRT kit with the precision aluminum mirror guarantees high quality optical performance of 5.53 ㎛ Full Width at Half Maximum (FWHM) at the field center.