• Title/Summary/Keyword: Astronomical observation

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Polarimetry of solar system small bodies using the Seoul National University 61cm telescope and TRIPOL

  • Jin, Sunho;Ishiguro, Masateru;Kwon, Yuna Grace;Geem, Jooyeon;Bach, Yoonsoo P.;Seo, Jinguk;Sasago, Hiroshi;Sato, Shuji
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.64.2-64.2
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    • 2019
  • It is known that lights scattered by comets and asteroids are partially polarized. From polarimetric observations of those objects, we can investigate physical properties, such as albedos, sizes of cometary dust particles and regolith of asteroids. Since the polarization degrees of those objects highly depend on their phase angles (Sun-object-observer's angles), long-term monitoring observations are required. Moreover, comets show unforeseeable activations (i.e., outbursts) which need follow-up observations to understand the mechanism. In order to realize such monitoring and transient observations, we installed the Triple-Range Imager and POLarimeter (TRIPOL) on the 61cm telescope of Seoul National University (Hereafter, SNU) Gwanak campus. With this combination, we can obtain g', r', i' bands photopolarimetric images simultaneously with $8.0^{\prime}{\times}8.0^{\prime}$ field of view and pixel resolution of 0.94" pixel-1. Here, we make a presentation regarding the photometric and polarimetric performances of TRIPOL on the SNU 61cm telescope. In addition, we introduce initial polarimetric results of asteroid and comets with the instruments. First, we determine the limiting magnitudes (defined as magnitudes for S/N=5) of $15.17{\pm}0.06$ (g'-band), $15.68{\pm}0.01$ (r'-band), $16.24{\pm}0.03$ (I'-band), respectively, with total 240-seconds exposure (four 60-seconds exposure images, each was taken at different rotation angle for the half-wave plate). Second, we found that the instrumental polarization is negligibly small, ($-0.32{\pm}0.04%$ in the g', $-0.36{\pm}0.05%$ in the r' and $-0.21{\pm}0.04%$ in the i'-bands), while the polarization efficiencies are large enough to maximize the performance (i.e., $97.52{\pm}0.03%$ in the g', $98.83{\pm}0.02%$ in the r' and $99.15{\pm}0.02%$ in the i'-bands). With the instruments, we made observations of three Jupiter-family comets, 21P/Giacobini-Zinner, 38P/Stephan-Oterma, and 46P/Wirtanen and plan to observe one near-Earth asteroid, (433) Eros, on a trial basis. Especially for comets, we discriminate signals from dust and gas to eliminate gas contamination, which are known to change observed degree of linear polarization, using multi-band images. We confirm that the phase angle dependency of these comets are consistent with previous observations, probably because polarimetric property of Jupiter-family comets are broadly homogeneous unlike asteroids. We will also describe future observation plans using TRIPOL and SNU 61cm telescope.

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A Comparative Analysis of Keywords in Astronomical Journals and Concepts in Secondary School Astronomy Curriculum (최근 천문학 연구 키워드와 천체 분야 교육과정 내용 요소 비교 분석)

  • Shin, Hyeonjeong;Kwon, Woojin;Ga, Seok-Hyun
    • Journal of The Korean Association For Science Education
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    • v.42 no.2
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    • pp.289-309
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    • 2022
  • In recent years, astronomy has been snowballing: including Higgs particle discovery, black hole imaging, extraterrestrial exploration, and deep space observation. Students are also largely interested in astronomy. The purpose of this study is to discover what needs to be improved in the current astronomy curriculum in light of recent scientists' researches and discoveries. We collected keywords from all papers published from 2011 to 2020 in four selected journals-ApJ, ApJL, A&A, and MNRAS- by R package to examine research trends. The curriculum contents were extracted by synthesizing the in-service teachers' coding results in the 2015 revised curriculum document of six subjects (Science, Integrated Science, Earth Science I, Earth Science II, Physics II, Convergence Science). The research results are as follows: first, keywords that appear steadily in astronomy are 'galaxies: formation, galaxy: active, star: formation, accretion, method: numerical.' Second, astronomy curriculum includes all areas except the 'High Energy Astrophysical Phenomena' area within the common science curriculum learned by all students. Third, it is necessary to review the placement of content elements by subject and grade and to consider introducing new concepts based on astronomy research keywords. This is an exploratory study to compare curriculum and the field of scientific research that forms the basis of the subject. We expect to provide implications for a future revision of the astronomy curriculum as a primary ground investigation.

A Study of Hagan's Ungi(河間運氣) theory and its application to modern society (劉河間의 運氣論과 그 運用에 관한 硏究)

  • Lee, Dong-Ho;Park, Chan-Guk
    • Journal of Korean Medical classics
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    • v.13 no.2 s.17
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    • pp.107-107
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    • 2000
  • 1. Ounyukki(五運六氣) theory was first developed from observation of astronomical phenomena. Natural phenomena were explained and incorporated into the concepts of Yukki(六氣), and Ohaeng(五行, the concept that all matter in the world are comprised of five fundamental elements), during Chon-guk(戰國) and Han(漢) periods. In that period. Kanji(干支, the method to present time with ten and twelve different kinds of symbol's combinations) was used to record Ounyukki(五運六氣). Theoretical study of Un-gi(運氣, the abbreviation of Ounyukki) was almost completed in Un-gichilpyon(運氣七篇) of Naekyong(內經). Un-gi(運氣) theory was further studied and considered to be very important socially, as well as medically, in Tang(唐), Song(宋), Kum(金), and Won(元) periods. Hagan(河間) published various studies based on Un-gi(運氣) theory in Kum won(金元) periods. 2. Hagan(河間) realized the limitation of a remedy method, of Sanghan(傷寒) theory. Therefore, he made an assumption that the prevalence of diseases in his period are closely related to Hwayol(火熱, a fire and a super-heat; two things out of Yukki(六氣)). His new theory was a result of the study on Kyongjon(經典, bibles of the oriental medicine) and the phenomena of nature. 3. Hagan(河間) used a combination of two basic theories of Pimuripsang(比物立象) and Hanhaesungjeron(亢害承制論) to make understood Hwayol(火熱) theory, Pimuripsang(比物立象) theory explains a method to appreciate the essence of things by comparing Sang(象, an expression of how something appears on the outside) and then making another Sang(象) from the comparison. Hanhaesungjeron(亢害承制論) is a theory to emphasize the importance of a balance of Yukki(六氣). It is that, if one of the elements is exceeded, other thing in the other five elements dominate the exceeded thing to control it for the balance between Yukki(六氣). In addition, he articulated P'yobon(標本. inside and outside of a thing) theory to differentiate the disease symptoms. These theories will help to distinguish real and fake symptoms of diseases, on which Hagan(河間) emphasized its importance. 4. Hagan(河間) published a new theory to explain Ounyukki(五運六氣) theory based on the observation of the nature and the experience from medical practice. And he added Chobyonggi(燥病機, course and rule causing disease in dry conditions) to Pyonggishipkujo(病機十九條, nineteen course and rule causing disease), it strengthened Pyonggi(病機, course and rule causing disease) theories. Moreover. he utilized Un-gi (運氣) theory in a real life situation by applying Un-giron(運氣論) to diagnosis like Maekchin(脈診, a method to diagnose by taking the pulse) and to prescription. 5. Modern society is an era in which it is hard to appreciate the principles of the changes due to the various unusual weather. Therefore, it is necessary to make a new paradigm using Un-gi(運氣) theory, like Hagan(河間) did in Kumwon(金元) period. 6. Unusual weather changes and the geriatric diseases such as cancer and diabetes, may have Sang(象) of Hwayol(火熱) theory at the other side. These diseases have been and will create more serious problems in modern society. As a method to solve these problems. it seems to be very important to understand and apply Hagan's(河間) Hawyol(火熱) theory to modern society.

A study of Hagan's Ungi(河間運氣) theory and its application to modern society (유하간(劉河間)의 운기론(運氣論)과 그 운용(運用)에 관한 연구(硏究))

  • Lee, Dong-Ho;Park, Chan-Guk
    • Journal of Korean Medical classics
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    • v.13 no.2 s.17
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    • pp.108-145
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    • 2000
  • 1. Ounyukki(五運六氣) theory was first developed from observation of astronomical phenomena. Natural phenomena were explained and incorporated into the concepts of Yukki(六氣), and Ohaeng(五行, the concept that all matter in the world are comprised of five fundamental elements), during Chon-guk(戰國) and Han(漢) periods. In that period. Kanji(干支, the method to present time with ten and twelve different kinds of symbol's combinations) was used to record Ounyukki(五運六氣). Theoretical study of Un-gi(運氣, the abbreviation of Ounyukki) was almost completed in Un-gichilpyon(運氣七篇) of Naekyong(內經). Un-gi(運氣) theory was further studied and considered to be very important socially, as well as medically, in Tang(唐), Song(宋), Kum(金), and Won(元) periods. Hagan(河間) published various studies based on Un-gi(運氣) theory in Kum won(金元) periods. 2. Hagan(河間) realized the limitation of a remedy method, of Sanghan(傷寒) theory. Therefore, he made an assumption that the prevalence of diseases in his period are closely related to Hwayol(火熱, a fire and a super-heat; two things out of Yukki(六氣)). His new theory was a result of the study on Kyongjon(經典, bibles of the oriental medicine) and the phenomena of nature. 3. Hagan(河間) used a combination of two basic theories of Pimuripsang(比物立象) and Hanhaesungjeron(亢害承制論) to make understood Hwayol(火熱) theory, Pimuripsang(比物立象) theory explains a method to appreciate the essence of things by comparing Sang(象, an expression of how something appears on the outside) and then making another Sang(象) from the comparison. Hanhaesungjeron(亢害承制論) is a theory to emphasize the importance of a balance of Yukki(六氣). It is that, if one of the elements is exceeded, other thing in the other five elements dominate the exceeded thing to control it for the balance between Yukki(六氣). In addition, he articulated P'yobon(標本. inside and outside of a thing) theory to differentiate the disease symptoms. These theories will help to distinguish real and fake symptoms of diseases, on which Hagan(河間) emphasized its importance. 4. Hagan(河間) published a new theory to explain Ounyukki(五運六氣) theory based on the observation of the nature and the experience from medical practice. And he added Chobyonggi(燥病機, course and rule causing disease in dry conditions) to Pyonggishipkujo(病機十九條, nineteen course and rule causing disease), it strengthened Pyonggi(病機, course and rule causing disease) theories. Moreover. he utilized Un-gi (運氣) theory in a real life situation by applying Un-giron(運氣論) to diagnosis like Maekchin(脈診, a method to diagnose by taking the pulse) and to prescription. 5. Modern society is an era in which it is hard to appreciate the principles of the changes due to the various unusual weather. Therefore, it is necessary to make a new paradigm using Un-gi(運氣) theory, like Hagan(河間) did in Kumwon(金元) period. 6. Unusual weather changes and the geriatric diseases such as cancer and diabetes, may have Sang(象) of Hwayol(火熱) theory at the other side. These diseases have been and will create more serious problems in modern society. As a method to solve these problems. it seems to be very important to understand and apply Hagan's(河間) Hawyol(火熱) theory to modern society.

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Astronomical Observation Environment Study focusing on Night Sky Brightness Variation under Light Pollution (광해에 따른 밤하늘의 밝기 변화를 중심으로 본 천문 관측 환경)

  • Lee, Jin-Hee;Choe, Seung-Urn;Jung, Jae-Hoon;Woo, Hong-Gyun
    • Journal of the Korean earth science society
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    • v.30 no.3
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    • pp.344-353
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    • 2009
  • By measuring the brightness of night sky, we have investigated light pollution around the observatory in the College of Education, Seoul National University. As a result of measuring the extinction coefficient and photometric constants by standardization, in January 28, 2009, the extinction coefficient found to be $k_B$=0.359 and photometric constant was $C_B$=4.397. In March 27, 2009, extinction coefficients were $k_B$=0.896 and $k_V$=0.725, and photometric constants were $C_B$=6.235 and $C_V$=6.027. Brightness of the night sky was measured from east, west, south, and north each by altitude of $20^{\circ}$, $40^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$. Data reduction and analysis was based on IRAF. Seeings for the each day of observation were 5.1 and 5.7 arcseconds in January 28 and March 27, respectively. Night sky spanned the magnitude range of $16{\leq}m_V$, $m_B{\leq}18$ We found that the brightness of night sky located at downtown was twice to four times brighter. On these observational conditions, limiting magnitude within 40cm-telescope becomes 11-13 magnitudes. Compared with Jan 28 and Mar 27, night sky brightness of January is 1 magnitude fainter than that of March in B filter.

Analysis of Observation Environment with Sky Line and Skyview Factor using Digital Elevation Model (DEM), 3-Dimensional Camera Image and Radiative Transfer Model at Radiation Site, Gangneung-Wonju National University (수치표고모델, 3차원 카메라이미지자료 및 복사모델을 이용한 Sky Line과 Skyview Factor에 따른 강릉원주대학교 복사관측소 관측환경 분석)

  • Jee, Joon-Bum;Zo, Il-Sung;Kim, Bu-Yo;Lee, Kyu-Tae;Jang, Jeong-Pil
    • Atmosphere
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    • v.29 no.1
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    • pp.61-74
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    • 2019
  • To investigate the observational environment, sky line and skyview factor (SVF) are calculated using a digital elevation model (DEM; 10 m spatial resolution) and 3 dimensional (3D) sky image at radiation site, Gangneung-Wonju National University (GWNU). Solar radiation is calculated using GWNU solar radiation model with and without the sky line and the SVF retrieved from the 3D sky image and DEM. When compared with the maximum sky line elevation from Skyview, the result from 3D camera is higher by $3^{\circ}$ and that from DEM is lower by $7^{\circ}$. The SVF calculated from 3D camera, DEM and Skyview is 0.991, 0.998, and 0.993, respectively. When the solar path is analyzed using astronomical solar map with time, the sky line by 3D camera shield the direct solar radiation up to $14^{\circ}$ with solar altitude at winter solstice. The solar radiation is calculated with minutely, and monthly and annual accumulated using the GWNU model. During the summer and winter solstice, the GWNU radiation site is shielded from direct solar radiation by the west mountain 40 and 60 minutes before sunset, respectively. The monthly difference between plane and real surface is up to $29.18M\;m^{-2}$ with 3D camera in November, while that with DEM is $4.87M\;m^{-2}$ in January. The difference in the annual accumulated solar radiation is $208.50M\;m^{-2}$ (2.65%) and $47.96M\;m^{-2}$ (0.63%) with direct solar radiation and $30.93M\;m^{-2}$ (0.58%) and $3.84M\;m^{-2}$ (0.07%) with global solar radiation, respectively.

Development of HTE-STEAM Constellation Education Program Using Astronomical Teaching Aid: Focused on Cultivating Core Competencies for Future Society through the Concept of Space and Time (천문 교구를 활용한 HTE-STEAM 별자리 교육 프로그램 개발 연구 : 시공간 개념을 통한 미래 사회 핵심역량 함양을 중심으로)

  • Ahra Cho;Yonggi Kim
    • Journal of the Korean Society of Earth Science Education
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    • v.17 no.1
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    • pp.34-48
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    • 2024
  • With the global rise in interest in competency-based education, the Ministry of Education of the Republic of Korea outlined six core competencies in the 2015 revised curriculum, essential for future society's 'creative and convergent talent'. This study introduces an HTE-STEAM constellation education program designed to develop the core competencies outlined in the 2015 revised curriculum and address the limitations of hands-on astronomy education. The program's effectiveness was assessed through a pilot test. The program was implemented at G Library, an out-of-school education site in Cheongju-si, Chungcheongbuk-do, targeting students from 3rd to 6th grade. The study's results include: First, the HTE-STEAM program significantly impacted all aspects of the STEAM attitude test except for 'self-concept', particularly influencing 'science and engineering career choice', 'consideration', and 'communication'. Thus, it has led to positive outcomes in the cultivation of future society's core competencies, including 'creative thinking skills', 'communication skills', and 'community skills'. Secondly, the HTE-STEAM constellation education program, despite covering the challenging concept of spacetime, was deemed easy by many students. Observations of students applying the spatial concepts they learned by using teaching aids suggest that the program was effective in enhancing students' understanding of the spatial structure of the sky and the universe. Additionally, this program aligns with the 2022 curriculum's updated standards for understanding the sky's spatial structure. Consequently, the HTE-STEAM constellation education program positively cultivates future society's core competencies and serves as a valuable complement to night observation practices in schools.

Characteristics of Yeong-dae Garden Recorded in Shijing and Mencius, and Its Perception in the Joseon Dynasty (『시경』과 『맹자』에 기록된 영대(靈臺) 원림의 특성과 조선시대 인식)

  • Lim, Hansol
    • Journal of the Korean Institute of Landscape Architecture
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    • v.52 no.4
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    • pp.120-136
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    • 2024
  • Yeong-dae(靈臺), Yeong-yu(靈囿), and Yeong-so(靈沼) - so-called 'Yeong-dae Garden' – appear in the poem 'Dae-ah(大雅)․Yeong-dae(靈臺)' in Shijing(詩經) which is considered the record of the earliest garden in East Asia, in the chapter 'Yanghyewang(梁惠王)' of Mencius(孟子). Focusing on those records, this research clarifies their characteristics and discusses the aspects related to garden practices in the Joseon Dynasty. The Yeong-dae Garden is the garden of King Wen of the Zhou Dynasty, who is considered a sage of Confucianism. It is considered to be the first imperial garden in China, and the basic form of all gardens consists of mountains and water. The characteristics of Yeong-dae Garden can be specified through the texts of Shijing and Mencius, the comments written by Zhu Xi and others, and later literature, such as Sambohwangdo. The characteristics of Yeong-dae Garden are as follows: In terms of form, the three spatial elements corresponding to raised ground, a wide area for raising animals, and a pond with fish form a simple arrangement; in terms of function, it combines observation and rest; and in terms of symbolism, it signifies the companionship of the public sentiment and the leader's sincerity. In literature from the Joseon Dynasty, Yeong-dae Garden mainly appear in historical materials related to the King, and its meaning shows an aspect of differentiation into two functions: an observatory for astronomical observation and a garden for rest and appreciation. For the intellectuals of Joseon who sought to restore an ancient ideal state like the Zhou Dynasty through Zhu Xi's Neo-Confucianism, the Yeong-dae Garden served as a control device to warn against royal garden's practices and a symbolic mechanism to expand its meaning of existence to good politics.

Design of a Wide-band Acousto-Optical Spectrometer for Radio Astronomical Observations (우주전파 관측을 위한 광대역 음향광학 전파분광기 설계)

  • 임인성;민경일;오승엽
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.6
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    • pp.1009-1017
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    • 2001
  • The acousto-optical spectrometer is designed by using 1 GHz bandwidth acousto-optic deflector for radio signal analysis. This system is a high resolution wide band spectrometer which uses I GHz bandwidth and a total of 2,048 channel charge coupled device. When we measured the spectrums of signals deflected by acousto-optical spectrometer, we confirmed the stability of the total system by repetitive observations of the same frequency, and each part of the system worked well. We installed this system onto 60 cm radio telescope, and observed 12CO(J= 1 ∼0) emission lines around CRL 2688, IRC 10216 and NGC 5005 Galaxy center. We could observe effectively very narrow band width radio spectrum as well as wide band radio spectrum. We also confirmed high sensitivity and resolution in observation of 12CO(J-10) omission line of NGC 5005 Galaxy center which is a weak signal.

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Recent Progress of MIRIS Development

  • Han, Won-Yong;Lee, Dae-Hee;Park, Young-Sik;Nam, Uk-Won;Jeong, Woong-Seob;Ree, Chang-Hee;Moon, Bong-Kon;Park, Sung-Joon;Cha, Sang-Mok;Lee, Duk-Hang;Park, Jang-Hyun;;Seon, Kwang-Il;Yang, Sun-Choel;Park, Jong-Oh;Rhee, Seung-Wu;Lee, Hyung-Mok;Matsumoto, Toshio
    • Bulletin of the Korean Space Science Society
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    • 2011.04a
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    • pp.23.4-23.4
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    • 2011
  • MIRIS is the main payload of the Science and Technology Satellite-3 (STSAT-3). which is being developed by KASI for infrared survey observation of the Galactic plane at Paschen alpha wavelength. Wideband filters in I and H band will also be used to observe cosmic infrared background. The MIRIS will perform astronomical observations in the near-infrared wavelengths of 0.9~2 ${\mu}m$ using a 256 ${\times}$ 256 Teledyne PICNIC FPA sensor providing a 3.67 ${\times}$ 3.67 degree field of view with a pixel scale of 51.6 arcsec. The flight model of the MIRIS has been recently developed, The system performance tests have been made in the laboratory, including opto-mechanics test, vibration test, thermal vacuum test and passive cooling test down to 200K, using a thermally controlled vacuum chamber. Several focus tests showed good agreements compared to initial design parameters. Recent efforts are being concentrated to improve the system performances, particularly to reduce readout noise level in electronics. After assembly and integration into the satellite bus, the MIRIS will be launched in 2012.

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