• 천문학논총
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• 제33권1호
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• pp.1-7
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• 2018

In order to encourage collaboration with North Korea in astronomy research field, we have studied the astronomical almanacs published in South and North Korea. The almanac contains fundamental astronomical data including not only daily calendar data but also unique characteristics selected by necessity in each country. We compared the South and North Korean astronomical almanacs in terms of contents, detailed descriptions, unique items, and so forth. We used the 2017 almanac for South Korea and 1993 almanac which is useful for this research for North Korea. We found that there were several differences between South and North Korean almanacs. The North Korean almanac is published for the astronomer or navigator, thus it has supplementary information about spherical astronomy such as precession of the north pole and position of celestial bodies. Whereas the South Korean almanac is published for the general public, and it distinctively contains luni-solar calendar, 24 solar terms, national holidays, etc. This study could be helpful for research cooperation between South and North Korea in astronomy.

• 천문학논총
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• 제31권3호
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• pp.57-63
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• 2016

We summarize our preliminary study on the research cooperation method in the astronomy field between Republic of Korea (South Korea) and Democratic People's Republic of Korea (North Korea). To investigate the recent astronomical activities of North Korea, we have surveyed the published records of research papers and international collaborations associated with North Korean astronomers. We found only 4 astronomical papers among the identified 260 SCI papers related to North Korean researchers for the past 11 years. North Korean astronomers had very few interactions with the international astronomical society before rejoining IAU in 2012. Recently, North Korea made several astronomical research exchanges with China and Netherlands. They seemed to attend several international conferences and present their research results. We have studied possibilities to establish international networks to encourage the cooperation between South and North, and suggest to start collaboration in the historical astronomy. The collaboration can be expanded gradually to other fields in astronomy. There are many obvious political difficulties to have interactions with North Koreans. However, it will be necessary to make a long-term plan considering the reunification.

• 천문학논총
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• 제39권2호
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• pp.39-51
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• 2024

Since the division of the Korean Peninsula in 1948, South and North Korea have independently developed their astronomical almanacs: Ryeokseo at the Korea Astronomy and Space Science Institute in South Korea and Cheonmunryeok at the Pyongyang Astronomical Observatory in North Korea. This study compares Ryeokseo and Cheonmunryeok for the year 2015, focusing on publication systems, content, terminology, and differences in data calculation methods. Additionally, it examines the calendars of South and North Korea from 2018 to 2023, analyzing similarities and differences in the representation of calendrical dates, public holidays, and other related aspects. The findings reveal that while the structure and content of the astronomical almanacs are similar in both countries, notable variances exist in the versions of ephemerides, time scales, and calculation precision. Consequently, identical data points are often recorded with slightly different values in each country's almanacs. Furthermore, approximately 28% of the terms used in North Korea's astronomical almanac are either not utilized in South Korea or have different definitions. Regarding calendar systems, those of South and North Korea are largely similar, resulting in no significant discrepancies in dates. However, there are notable differences in the observance of public holidays. While traditional holidays are common to both, most holidays are distinctively celebrated. Notably, North Korea does not observe religious holidays, and many of its holidays are associated with the regime.

• Journal of Astronomy and Space Sciences
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• 제24권2호
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• pp.91-98
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• 2007

The existence of the North-South asymmetry of the solar activity is widely accepted even though the phenomenon is not yet satisfactorily understood. We have studied the temporal variations in the North-South asymmetry of the sunspot area during the period from May in 1874 to April in 2007. The combined data have been examined for periodicity in the solar activity North-South asymmetry. We have found that (i) solar northern and southern hemispheres show an asymmetric behavior, in terms of a sunspot area, (ii) sunspot areas in northern and southern hemispheres show clearly the 11 year periodicity when they were analyzed separately, as they do when analyzed together, (iii) in addition to the general 11 year periodicity in both northern and southern hemisphere solar activities, there are also noticeable shorter periodicities other than the 11 year periodicity in the asymmetry in North-South activity. Finally, we conclude by pointing out the importance of studying the North-South asymmetry of the solar activity.

• 천문학회보
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• 제46권2호
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• pp.63.1-63.1
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• 2021

We present status of solar astronomy in North Korea through analysis of research papers written by North Korea scientists. For the study, we collected 42 papers published in North Korea and international journals. We have analyzed the papers statistically according to three criteria such as research subject, research field, and research members. The main research subjects are the sunspot (28%), observation system (21%), and space environments (19%). The research fields are distributed with data analysis (50%), numerical method (29%), and instrument development (21%). There have been 25 and 9 researchers in the solar astronomy and space environment, respectively since 1995. North Korea's solar research activities were also investigated in three area: instrument, solar physics, and international research linkage. PAO(Pyongyang Astronomical Observatory) has operated two of sunspot telescope and solar horizontal telescope for spectroscopy and polarimetry, but there is no specific information on solar radio telescopes. North Korea has cooperated in solar research with Europe and China. We expect that the results of this study will be used as useful resource in supporting astronomical cooperation between South and North Korea in the future.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.25-30
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• 2009

태양의 북-남 비대칭성을 고려하여 태양활동과 기후변화 사이의 관계에 대하여 연구하였다. 이를 위해 흑점 수와 지구연평균 기온아노말리(temperature anomalies) 시계열을 이용하여 이동 상관계수를 계산하였고 상관계수의 부호가 바뀌는 시점을 태양의 북-남 비대칭성의 부호가 바뀌는 시점과 비교하였다. 상관계수의 부호는 1907년을 기준으로 음의 상관에서 양의 상관으로 바뀌었고 1985년을 기준으로 양의 상관이 을의 상관으로 바뀌었다. 이 둔 시점은 태양의 북-남 비대칭성의 부호가 바뀌는 시점과 잘 일치하였다. 흑점 수에 대한 기온아노말리 변화 그래프를 통해 태양활동과 기후변화 사이의 관계가 1907년과 1985년으로 나뉘어진 세 기간으로 분류되었고 각 기간에 대해서 기온아노말리의 흑점 수에 대한 상관계수를 계산하였다. 이를 통해 태양의 남반구에서 태양활동이 강할 때는 태양활동과 기후변화의 관계가 음의 상관을 보이고 북반구의 태양활동이 강할 때는 양의 상관을 보인다는 것을 확인하였다.

• Journal of Astronomy and Space Sciences
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• 제36권4호
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• pp.225-234
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• 2019

We explore the associations between the total sunspot area, solar north-south asymmetry, and Southern Oscillation Index and the physical characteristics of clouds by calculating normalized cross-correlations, motivated by the idea that the galactic cosmic ray influx modulated by solar activity may cause changes in cloud coverage, and in turn the Earth's climate. Unlike previous studies based on the relative difference, we have employed cloud data as a whole time-series without detrending. We found that the coverage of high-level and low-level cloud is at a maximum when the solar north-south asymmetry is close to the minimum, and one or two years after the solar north-south asymmetry is at a maximum, respectively. The global surface air temperature is at a maximum five years after the solar north-south asymmetry is at a maximum, and the optical depth is at a minimum when the solar north-south asymmetry is at a maximum. We also found that during the descending period of solar activity, the coverage of low-level cloud is at a maximum, and global surface air temperature and cloud optical depth are at a minimum, and that the total column water vapor is at a maximum one or two years after the solar maximum.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.251-253
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• 2004

Automated east/west and north/south station-keeping maneuvers were simulated for the geostationary COMS (Communication, Ocean and Meteorological Satellite) satellite that will be launched around year 2008, The satellite has to be maintained within ${\pm}0.05^{\circ}$ at the nominal longitude of $128.2^{\circ}\;E$. The general perturbation method was used to keep the position of the geostationary satellite. Weekly based east/west and biweekly based north/south station-keeping maneuvers were investigated. The sun pointing perigee control method and two-bum strategy were used for the east/west station-keeping maneuver. Switching the right ascension of the ascending node to descending node was adopted for the north/south station-keeping maneuver. One year station-keeping maneuver was demonstrated and various station-keeping orbital parameters were analyzed.

• 천문학논총
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• 제36권2호
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• pp.37-45
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• 2021

We have analyzed 42 research papers regarding on the solar astronomy written by North Korea scientists to investigate the current status of astronomical activities in North Korea. The papers are surveyed from the 'Bulletin of Astronomy', the 'Physics', the 'Bulletin of Academy of Science', and the 'Natural Science' in North Korea, and SCI journals. In addition, we refer to the presentation material announced in the 2015 IAU by director of Pyongyang Astronomical Observatory (PAO) and the 2013 OAD/IAU reports. We have analyzed the papers statistically according to three criteria such as research subject, research field, and research members. The main research subjects are the sunspot (28%), observation system (21%), and space environments (19%). The research fields are distributed with data analysis (50%), numerical method (29%), and instrument development (21%). There have been 25 and 9 researchers in the solar astronomy and space environment, respectively since 1995. North Korea's solar research activities were also investigated in three area: instrument, solar physics, and international research linkage. PAO has operated two of sunspot telescope and solar horizontal telescope for spectroscopy and polarimetry, but there is no specific information on solar radio telescopes. North Korea has cooperated in solar research with Europe and China. We expect that the results of this study will be used as useful resource in supporting astronomical cooperation between South and North Korea in the future.

• Journal of Astronomy and Space Sciences
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• 제24권4호
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• pp.261-268
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• 2007

We have studied the temporal variation in the North-South asymmetry of the sunspot area during the period from 1874 to 2007. Though the 9-year periodicity is commonly reported, shorter periodicities is still under study. We employ the cepstrum analysis method to analyze the noisy power spectrum of the North-South asymmetry. We demonstrate that the cleaned power spectrum shows reduction of the spurious back-ground noise level. Some of short period peaks in the power spectrum disappear after deconvolution. It should be, however, pointed out that power spectrum might look less noisy because of a filtering process during deconvolution. We conclude by pointing out that a more sophisticate filtering algorithm is required to produce a precise and reliable periodicity estimate.