• Bulletin of the Korean Space Science Society
• /
• 1998.10a
• /
• pp.26.2-26
• /
• 1998

No Abstract.See Full-text

• Publications of The Korean Astronomical Society
• /
• v.15 no.spc1
• /
• pp.119-126
• /
• 2000

The BOES (BOAO Echelle Spectrograph), a fiber-fed echelle spectrograph of the BOAO 1.8 m telescope, has been designed and now is being manufactured. The BOES follows a white pupil design collimated with two off-axis parabolic mirrors. The 136mm collimating beam leaving the 41.59 grooves/mm R4 echelle grating is refocused near the narrow folding mirror. Through the two cross-disperser prisms and $\phi250 mm(f/1.5)$ transmission camera, the beam images on EEV $2k\times4k$ CCD. The BOES can take the wavelength range of 3700 to $10100{\AA}$ at a single spot with spectral resolution R = 20000 to 40000 depending on the fiber set employed. We describe the key sciences and performance, current status of construction, and future plan of the BOES.

• Bulletin of the Korean Space Science Society
• /
• 2000.10a
• /
• pp.54-54
• /
• 2000

No Abstract, See Full Text

• Journal of Korean Association for Spatial Structures
• /
• v.16 no.2
• /
• pp.47-54
• /
• 2016

It is very important to calculate natural frequency of the observatory tower correctly because it is keenly affected by wind response vibration due to its large slenderness ratio, weight and small damping ratio. Additionally, suggestion equation of natural frequency being used in the design phase has considerable difference between actual measured value thereby making it inappropriate to be used in the serviceability design of the observatory tower. Therefore, this paper conducted an ambient vibration measuring on 10 observatory towers through mobile-phone application thereby calculating the natural frequency and comparing the result with the domestic and foreign standards and that of the eigen-value analysis. This paper suggested approximate equation of the natural frequency of the observatory tower; T=0.0266H. The square of the corelation coefficient is 0.940, which is high.

• The Bulletin of The Korean Astronomical Society
• /
• v.25 no.1
• /
• pp.54-54
• /
• 2000

• Bulletin of the Korean Space Science Society
• /
• 2003.10a
• /
• pp.41-41
• /
• 2003

Satellite formation flying is currently an active area of research in the aerospace engineering. There are many categories for this research such as the determination of initial conditions, formation keeping, configuration and reconfiguration. In this study, a tracking controller using sliding mode techniques is designed to control a satellite for the satellite formation flying. In general, Hill's equations are used to describe the relative motion of the follower satellite with respect to the leader satellite. But, the modified Hill's equations considering J2 perturbation were used for the design of sliding mode controller. Sliding mode control law causes the chattering phenomenon because it is a discontinuous control. Dead-zone was used to avoid the chattering. The Extended Kalman filter was applied to estimate the state vector based on the measurements of relative distance and velocity between two satellites.

• Journal of Astronomy and Space Sciences
• /
• v.14 no.2
• /
• pp.259-268
• /
• 1997

We present the development process of a prototype CCD imaging system which is being built at Korea Astronomy Observatory(KAO) for astronomical applications. The CCD imaging system requires very low noise and high stability characteristics and is widely used for astronomical purposes from infrared to ultraviolet wavelength regions. However its system design, particularly for the controller design technique, as heart of the system, is not secured in Korea so far. The prototype electronics developed in this study consists of a signal chip controller which was implemented in an EPLD(Erasable Programable Logic Device) and an analog driver, a video processor with a LN2 cooling cryostat. A PC system was employed to control the whole system and to store the image data considering compatibility of the system. We have successfully obtained the first image in the laboratory with the prototype of this imaging system, and an image of the M15 at Sobaeksan Astronomy Observatory.

• Publications of The Korean Astronomical Society
• /
• v.19 no.1
• /
• pp.65-70
• /
• 2004

An imaging spectrograph concept optimized for extended far-ultraviolet emission sources is presented. Although the design was originally developed for FIMS aboard the first Korean science satellite STSAT-l launched on September 27, 2003, no rigorous theoretical background of the spectrograph design has been published. The spectrograph design employs an off-axis parabolic cylinder mirror in front of a slit that guides lights to a diffraction grating. The concave grating provides moderate spatial resolution over a large field of view. This mapping capability is absent in most astronomical instruments but is crucial to the understanding of the nature of a variety of astrophysical phenomena. The aberration theory presented in this paper can be extended to holographic gratings in order to improve the spatial as well as the spectral resolutions.

• Journal of Ecology and Environment
• /
• v.47 no.4
• /
• pp.187-192
• /
• 2023

The United States (US) National Science Foundation's (NSF's) National Ecological Observatory Network (NEON) is a continental-scale observation facility, constructed and operated by Battelle, that collects long-term ecological data to better understand and forecast how US ecosystems are changing. All data and samples are collected using standardized methods at 81 field sites across the US and are freely and openly available through the NEON data portal, application programming interface (API), and the NEON Biorepository. NSF led a decade-long design process with the research community, including numerous workshops to inform the key features of NEON, culminating in a formal final design review with an expert panel in 2009. The NEON construction phase began in 2012 and was completed in May 2019, when the observatory began the full operations phase. Full operations are defined as all 81 NEON sites completely built and fully operational, with data being collected using instrumented and observational methods. The intent of the NSF is for NEON operations to continue over a 30-year period. Each challenge encountered, problem solved, and risk realized on NEON offers up lessons learned for constructing and operating distributed ecological data collection infrastructure and data networks. NEON's construction phase included offices, labs, towers, aquatic instrumentation, terrestrial sampling plots, permits, development and testing of the instrumentation and associated cyberinfrastructure, and the development of community-supported collection plans. Although colocation of some sites with existing research sites and use of mostly "off the shelf" instrumentation was part of the design, successful completion of the construction phase required the development of new technologies and software for collecting and processing the hundreds of samples and 5.6 billion data records a day produced across NEON. Continued operation of NEON involves reexamining the decisions made in the past and using the input of the scientific community to evolve, upgrade, and improve data collection and resiliency at the field sites. Successes to date include improvements in flexibility and resilience for aquatic infrastructure designs, improved engagement with the scientific community that uses NEON data, and enhanced methods to deal with obsolescence of the instrumentation and infrastructure across the observatory.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.2
• /
• pp.20-30
• /
• 1999

We have made the single side hand filter for the dual channel receiver which is a heterodyne receiver to observe the cosmic radio waves with 100GHz band ranged from 85GHz to 115GHz and 150GHz band ranged from 125GHz to 175GHz simultaneously. We have introduced the filter theory using the principle of the Martion-Puplett interferometer, which has the characteristics of rotated polarization. To reduce the loss of the transmission and beam coupling which are caused from the path difference associated with the intermediate frequency the design and the implementation have been intensely considered. The receiver needs two filters with different characteristics each other. Because each of them has the optimum positions as a function frequency at which the signal frequency is fed to mixer and the image frequency is rejected to the image termination load. The intermediate frequency and its band width have been also evaluated. We have measured the property of two filters using the vector network analyser and the beam measurement system which is made by us. The responses of the filter as a function of the position and the frequency are compared with the theory. It is shown that not only the measured values are very close to the theoretical values, but also the image rejection ratios are better than 22dB for both filters. Through successful observation using a dual channel receiver with two manufactured filters, the performance of the filters has finally verified.