• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.66-68
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• 2011

Chollian is a geostationary satellite, and its bipropellant propulsion system is mainly composed of one main engine for orbit transfer and fourteen thrusters for on-station operations. The Chollian was launched successfully at Kourou Space Center in French Guiana. After it separated from the launcher, the propulsion system was initialised automatically. Then three times of main engine firing were successfully performed, and the target obit insertion was accomplished. This paper details the major CPS events during LEOP phase for the Chollian satellite.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.207-210
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• 2011

Chollian bipropellant propulsion system is composed of one main engine for orbit transfer and fourteen thrusters for on-station operations. The design and analyses of the propulsion system were carried out in the framework of international collaboration. Following the system integration and testings required, the Chollian was transported to Kourou Space Center in French Guiana and launched successfully. After it separated from the launcher, the propulsion system was initialised automatically. Then three times of main engine firing were successfully performed, and the target obit insertion was accomplished.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.753-760
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• 2011

The satellite Chollian was successfully launched on June 27, 2010 and is expected to perform its communication, oceanographic, and meteorological duties for seven years. The follow-up launch of the Chollian satellite is already being planned, and diverse studies are under way to enable the use of the Korean satellite data. Studies are also being actively conducted in and out of Korea to visualize the meteorological data on the open-source virtual globes. The meteorological data include ground observation, satellite, and digital-model data. In this study, an efficient three-dimensional technique was developed to visualize typhoons on the virtual globes using the Chollian satellite data. This study was conducted to provide service to the public via the scientific visualization of the satellite image data, and to create an efficient satellite image analysis environment for meteorological researchers.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.94-100
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• 2011

This paper gives a brief overview of the COMS CPS development process from start to finish. The manufacturing techniques used for CPS were founded on established generic processes that have been developed and proven on previous satellite programs, and have used the expertise and facilities in the framework of international collaboration. Manufacture and testing of the CPS were successfully accomplished, and COMS CPS demonstrated good performance in the launch phase.

• Journal of the Korean Society for Library and Information Science
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• v.24
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• pp.171-204
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• 1993

The purpose of this study is to verify the hypothesis that the contents and range of library services are changed as the use of videotex systems increases. 1000 members of Chollian II were chosen as subjects for this study and the questionnaire was posted to them. The returned responses to questionnaire were analyzed with the statistical software packages 'SAS PC' and 'STATGRAPHICS'. The findings and conclusions of this study are summarised as follows: 1. Users of Chollian II make more use of videotex systems in seeking daily information than in seeking scholarly and professional information. It seems desirable to co-ordinate the services of videotex systems and libraries by redefining the traditional boundary of the two systems. Users will then conveniently get daily information through videotex servics, scholarly and professional information through the reference service of libraries. 2. Sex does not make any significant difference in the use of videotex systems. Most frequent use of videotex systems is made by those at the age of thirties. Businessmen and enterprisers make the most frequent use of videotex systems. Those of higher education are the best users. 3. As the use of videotex systems increases, use of newspapers and periodicals decreases while its increase rarely has influence on the use of library materials. 4. There is limited correlation between the use of videotex systems and that of library services. The increase of the use of videotex systems does not significantly increase or decrease the use of libraries. It changes, however, the pattern and methods of information services provided by libraries. 5. Users of special libraries make the most frequent use of videotex systems and there is not much difference in the use by users of other kinds of libraries.

• Journal of the Korean Solar Energy Society
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• v.39 no.3
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• pp.47-57
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• 2019

Clear sky indices were estimated by various ways based on in-situ observation and satellite-derived solar irradiance. In principle, clear sky index defined by clear sky solar irradiance indicates the impacts of cloud on the incoming solar irradiance. However, clear sky index widely used in energy sciences is formulated by extraterrestrial irradiance, which implies the extinction of solar irradiance due to mainly aerosol, water vapor and clouds drops. This study examined the relative difference of clear sky indices and then major characteristics of clear sky irradiance when sky is clear are investigated. Clear sky is defined when clear sky index based on clear sky irradiance is higher than 0.9. In contrast, clear sky index defined by extraterrestrial irradiance is distributed between 0.4 and 0.8. When aerosol optical depth and air mass coefficient are relative larger, solar irradiance is lower due to enhanced extinction, which leads to the lower value of clear sky index defined by extraterrestrial irradiance.

• The Plant Pathology Journal
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• v.15 no.6
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• pp.340-344
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• 1999

Fungicide-resistant isolates of Monilinia fructicola grew readily on media amended with 0.1, 1.0, 10, 100 and $1,000\mu\textrm{g}$ a.i./ml of carendazim, benomyl, or thiophanate-methyl. However, sensitive isolates did not grow on media amended even with $0.1\mu\textrm{g}$ a.i./ml of carbendazim, $1.0\mu\textrm{g}$ a.i./ml of benomyl or thiophanate-methyl. The fitness compositions including mycelial growth on fungicide-free medium, sporulation on fungicide-free medium and pear, and virulence on pear were not different between resistant and sensitive isolates. The resistant isolates persisted carbendazim resistance during multiple subdulturing and long term storage. The competitive ability of resistant isolates obtained from peach orchards in Korea was similar to those of sensitive isolates.

• Korean Security Journal
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• no.6
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• pp.195-213
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• 2003

This is a case study on the violent collective activities of spectators in professional soccer games. The purpose of this study is to examine the reasons and the processes of the activities. In order to achieve the purpose well, I analyzed two cases of violent collective activities in spectators of professional soccer games that were held on June 24 and July 28 in 2001. The data for this study was collected from 14 kinds of daily newspapers from June 10 to August 20 in 2001 to maintain the objective validity of the outline, the reasons, and the processes of the violent collective activities of spectators in two cases. The data was collected from Korea Integrated News Database System(KINDS) of Korea Press Foundation, and Chollian, on-line service of DACOM, for its efficiency, accuracy and promptness. On the basis of the above-mentioned method as well as the consequences of data analysis, I've reached to a conclusion as follows. The reasons of the violent collective activities of spectators in professional soccer games were the mass effect, the activities of players, umpires and the results of games, etc. The violent collective activities of spectators in professional soccer games need pre-requirements and have relationships with special affairs that are developed in a regular sequence. In other words, a collective activity gives an effect on another one directly or indirectly. Therefore, this study shows that we can reduce or prevent the damages by the violent collective activities of spectators in sport games when we analyze the processes of collective activities and make a previous counter-measure for that.

• Journal of Information Technology Application
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• v.3 no.4
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• pp.93-117
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• 2001

Computer-based on-line communications help to exchange easily information for us. For this reason, on-line communication expands personal computer users'information availability and furnishes users with interactive communication capability. This research focused on the pattern the use of on-line communication and such individual-level factors that are believed to affect on the use of this technology as personal psychological traits and perceived usefulness of the technology. Data were collected from randomly selected samples out of registered college or office worker members of Korean on-line communication services such HiTel, Chollian, Nownuri, and Unitel. The result of the study showed that perceived usefulness of the on-line services affects the level of use most strongly. Individual psychological style was also related to some aspects of the use of on-line communication. Specifically, the more introvert the users, the higher was the level of use of on-line communication.

• Journal of the Korean earth science society
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• v.39 no.2
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• pp.131-138
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• 2018

The purpose of this study is to improve the quantitative precipitation estimation method based on satellite brightness temperature. The non-linear equation for rainfall estimation is improved by analysing precipitation cases around the Korean peninsula in summer. Radar reflectivity is adopted the CAPPI 1.5 and CMAX composite fields that provided by the Korea Meteorological Agency (KMA). In addition, the satellite data are used infrared, water vapor and visible channel measured from meteorological imager sensor mounted on the Chollian satellite. The improved algorithm is compared with the results of the A-E method and CRR analytic function. POD, FAR and CSI are 0.67, 0.76 and 0.21, respectively. The MAE and RMSE are 2.49 and 6.18 mm/h. As the quantitative error was reduced in comparison to A-E and qualitative accuracy increased in compare with CRR, the disadvantage of both algorithms are complemented. The method of estimating precipitation through a relational expression can be used for short-term forecasting because of allowing precipitation estimation in a short time without going through complicated algorithms.