• Cross-Cultural Studies
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• v.35
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• pp.185-214
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• 2014

This paper presents an investigation into the forms of master archer Huhdai Mergen from Mongolian mythology and his character through archery. In Mongolian mythology, master archer Huhdai Mergen is usually connected to the regulation of the sun, the moon, and the stars in Heaven and the creation of stars. Such a series of acts are conducted through archery, which used to be performed as an incantatory ritual to resolve a disaster in life, dispel an evil spirit, and pray for affluence as well as for hunting. In Mongolian mythology, Huhdai Mergen is a master archer and hunter that rises to Heaven while hunting a deer and becomes Sirius with the deer becoming Orion. The Mongolian have believed that the two constellations protect them since ancient times. While Orion is related to the deer totem, Huhdai Mergen or Sirius is related to the wolf totem faith. Huhdai Mergen takes too much pride in his archery skills and ends up causing damage to himself, which can be understood as a pattern of controlling the power of personified Huhdai Mergen through excessive natural force. He also has something to do with Polaris, which is regarded as the stake to bind his horse to by the Mongolian. They also believe that their ancestral gods reside in the horse stake or column. The stake is the residence of Huhdai Mergen protecting the Mongolian people, which reflects his aspect as an ancestral god. He is also depicted as the god of thunder and lightning born in a cow. The stones he throws and the arrows he shoots in Heaven are the embodiments of thunder and lightning. The Mongolian have understood lightning of dispelling an evil spirit and striking wicked things as the arrow of Huhdai Mergen. The god of thunder and lightning has the attributes of a fertility god such as eliminating bad devils and bringing affluence. Huhdai Mergen is also manifested as the creator to create the earth and the savior to save mankind. Such forms all derive from his archery skills.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.187-195
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• 2019

The purpose of this study is to investigate the effect of tourism councils on the activation of rural tourism by comparing the rural tourism sites with the tourism councils and the rural tourism sites without tourism councils. The comparative indicators were divided into statistical quantitative indicators such as number of tourists, sales volume, and income level, and qualitative indicators of satisfaction, return visit, and word of mouth intentions. As a result of the study, it was found that all the items of the quantitative and qualitative indicators were active in the rural tourism area where the tourism council was composed. This can be attributed to the fact that the members of the tourism council consist of administrative agencies, experts, tourism operators, experts, etc., and constantly develop strategic programs such as diverse opinions and unique constellations. Therefore, in order to revitalize rural tourism in the future, it can be said that the tourism council should be constructed, and institutional devices should be prepared so that experts and residents in each field can participate equally.

• Korean Journal of Remote Sensing
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• v.38 no.5_2
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• pp.661-667
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• 2022

As remote sensing and GIS have been considered to be essential technologies for disasters information production, researches on developing methods for analyzing spatial data, and developing new technologies for such purposes, have been actively conducted. Especially, it is assumed that the use of remote sensing and GIS for disaster management will continue to develop thanks to the launch of recent satellite constellations, the use of various remote sensing platforms, the improvement of acquired data processing and storage capacity, and the advancement of artificial intelligence technology. This spatial issue presents 10 research papers regarding ship detection, building information extraction, ocean environment monitoring, flood monitoring, forest fire detection, and decision making using remote sensing and GIS technologies, which can be applied at the disaster prediction, monitoring and response stages. It is anticipated that the papers published in this special issue could be a valuable reference for developing technologies for disaster management and academic advancement of related fields.

• Journal of Space Technology and Applications
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• v.2 no.1
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• pp.1-12
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• 2022

In this paper, we described the development of a drag augmentation device for nanosatellite. Recently, space industry has entered the New Space era, and barriers to entry into Low Earth Orbit (LEO) for artificial objects such as small rockets and nanosatellite mega constellations have been significantly lowered. As a result, the number of space debris is increasing exponentially, and it is approaching as a major threat to satellite currently in operation as well as satellites to be launched in near future. To prevent this, international organizations like Inter-Agency Space Debris Coordination Committee (IADC) have been proposed space debris mitigation guidelines. The Korea Aerospace Research Institute (KARI) conducted KARI Rendezvous & Docking demonstration SATellite (KARDSAT) project, the first nanosatellites for rendezvous and docking technology demonstration in Korea, and we also developed drag augmentation device for KARDSAT Target nanosatellite that complied with the international guideline of post-mission disposal.

• Journal of Korean Elementary Science Education
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• v.41 no.1
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• pp.93-105
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• 2022

This study investigated the aspects of how three preservice elementary school teachers conducted the data-text transforming discourses in their science simulation teaching and how their epistemological conversations worked for learners' construction of scientific knowledge. Three preservice teachers, who had presented simulation teaching on the seasonal change of constellations, participated in the study. The results revealed that one preservice teacher, who had implemented the transforming discourses of data-to-evidence and model-to-explanation, appeared to facilitate learners' knowledge construction. The other two preservice teachers had difficulty helping learners construct science knowledge due to their lack of transforming discourses. What we should consider for improving preservice elementary school teachers' teaching competencies was discussed based on a detailed comparison of three cases of preservice teachers' data-text transforming.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.8-16
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• 2022

This paper presents the orbital control for positioning micro synthetic aperture radar (SAR) satellites for all-weather monitoring around the Korean Peninsula. In Small SAR technology experimental project (S-STEP) developed in Korea, multiple satellites are placed at equal intervals in multiple orbital planes to secure an average revisit period for the region around the Korean Peninsula. Satellites entering the same orbital plane use ion thrusters to control their orbits and the separation velocity from the launch vehicle to distribute them evenly across the orbit. For an orbital that places the satellites equally spaced in the same orbital plane, the shape of the satellite constellation is formed by adjusting the difference in drift rates between the satellites. This paper presents, different types of satellite constellations, and the results of satellite constellation placement according to launch strategies are presented. In addition, a method and limitations in shortening the duration of orbital deployment are presented.

• International Journal of Computer Science & Network Security
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• v.23 no.5
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• pp.172-178
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• 2023

In this paper, performance of autoencoder based OFDM communication systems is compared with IEEE 802.11a Wireless Lan System (Wi-Fi). The proposed autoencoder based OFDM system is composed of the following steps. First, one sub-carrier's transmitter - channel - receiver system is created by autoencoder. Then learning process of the one sub-carrier autoencoder generates constellation map. Secondly, using the plural sub-carrier autoencoder systems, parallel bundle is configured with inserting IFFT and FFT before and after the channel to configure OFDM system. Finally, the receiver part of the OFDM communication system was updated by re-learning process for adapting channel condition such as multipath channel. For performance comparison, IEEE802.11a and the proposed autoencoder based OFDM system are compared. For channel estimation, Wi-Fi uses initial long preamble to measure channel condition. but Autoencoder needs re-learning process to create an equalizer which compensate a distortion caused by the transmission channel. Therefore, this autoencoder based system has basic advantage to the Wi-Fi system. For the comparison of the system, additive random noise and 2-wave and 4-wave multipaths are assumed in the transmission path with no inter-symbol interference. A simulation was performed to compare the conventional type and the autoencoder. As a result of the simulation, the autoencoder properly generated automatic constellations with QPSK, 16QAM, and 64QAM. In the previous simulation, the received data was relearned, thus the performance was poor, but the performance improved by making the initial value of reception a random number. A function equivalent to an equalizer for multipath channels has been realized in OFDM systems. As a future task, there is not include error correction at this time, we plan to make further improvements by incorporating error correction in the future.

• Publications of The Korean Astronomical Society
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• v.39 no.1
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• pp.1-12
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• 2024

In this study, we investigated the time signal devices of Deungnu (circa 1270) and Gungnu (1354), the water clocks produced during the Yuan Dynasty (1271-1368). These clocks influenced Heumgyeonggaknu (1438) of the Joseon Dynasty (1392-1910), exemplifying the automatic water clocks of the Yuan Dynasty. Deungnu, Gungnu, and Heumgyeonggaknu can be considered as automatic mechanical clocks capable of performances. The Jega-Yeoksang-Jip (Collection of Calendrical and Astronomical Theories of Various Chinese Masters) contains records of Deungnu extracted from the History of the Yuan Dynasty. We interpreted these records and analyzed reproduction models and technical data previously produced in China. The time signal device of Deungnu featured a four-story structure, with the top floor displaying the four divine constellations, the third floor showcasing models of these divinities, the second floor holding 12-h jacks and a 100-Mark ring, and the first floor with four musicians and a 100-Mark Time-Signal Puppet providing a variety of visual attractions. We developed a 3D model of Deungnu, proposing two possible mechanical devices to ensure that the Time-Signal Puppet simultaneously pointed to the 100-Mark graduations in the east, west, south, and north windows: one model reduced the rotation ratio of the 100-Mark ring to 1/4, whereas the other model maintained the rotation ratio using four separate 100-Mark rings. The power system of Deungnu was influenced by Suunuisangdae (the water-driven astronomical clock tower) of the Northern Song Dynasty (960-1127); this method was also applied to Heumgyeonggaknu in the Joseon Dynasty. In conclusion, these automatic water clocks of East Asia from the 13th to 15th centuries symbolized creativity and excellence, representing scientific devices that were the epitome of clock-making technology in their times.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.3
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• pp.221-235
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• 2024

Errors included in Global Navigation Satellite System (GNSS) measurements degrade the performance of user position estimation but can be mitigated by spatial correlation properties. Augmentation systems providing correction data can be broadly categorized into State Space Representation (SSR) and Observation Space Representation (OSR) methods. The satellite-based cm-level augmentation service based on the SSR broadcasts correction data via satellite signals, unlike the traditional Real-Time Kinematic (RTK) and Network RTK methods, which use OSR. To provide a large amount of correction data via the limited bandwidth of the satellite communication, efficient message structure design considering service area, correction generation, and broadcast intervals is necessary. For systematic message design, it is necessary to analyze the influence of error components included in GNSS measurements. In this study, errors in satellite orbits, satellite clocks for GPS, Galileo, BeiDou, and QZSS satellite constellations ionospheric and tropospheric delays over one year were analyzed, and their spatial decorrelations and linear modeling characteristics were examined.

• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.181-198
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• 2008

Designing satellite constellations providing partial coverage of certain regions becomes more important as small low-altitude satellites receives an increasing attention due to its cost-effectiveness analysis. Generally, Walker's method is a standard constellation method for global coverage but not effective for partial coverage. The purpose of this study is to design optimal constellation of satellites for effective observation in Korean peninsula regions. In this study, a new constellation design method is presented for partial coverage, using direct control of satellites' orbital elements. And also, a ground repeating circular orbit is considered for each satellite's orbit with the Earth oblateness effect. As the results, at least four satellites are required to observe the Korean peninsula regions effectively when minimum elevation angle is assumed as 12 degrees. The results from new method are better than those from the best Walker method. The proposed algorithm will be useful to design satellite constellation missions of Korea in future.