• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.73-83
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• 2005

On-The-Fly (OTF) observation method is developed for the efficient use of 6 M radio telescope at Seoul Radio Astronomy Observatory (SRAO). This technique, in which data and information of antenna position are recorded synchronously while driving a telescope regularly and rapidly across a field, provides more efficient use of telescope time and better calibration of the acquired data than the traditional point-to-point observation method does. For the realization of the method, we (1) added RT-Linux modules to the existing operating system, (2) replaced digital voltmeter with voltage-to-frequency converter, and (3) modified many SRAO observation programs. By observing Moon and G78.2+2.7 using this method and comparing them with previous observations, we verify the successful operation and efficiency of the OTF observation mode.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.255-260
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• 1992

It is reported on the methodology of signal detection in noise which is based on a comparison of statistical parameters of observation sample from region of frequency-time noise space where a signal may be present and observation sample from region of this noise space and it is known a priori about the latter that the signal is absent in this region.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.690-698
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• 1990

Among the target identification algorithms presented up to now, the NNR algorithm utilize multifrequency and single observation method. But it is generally known that its implementation is extremely difficult. In this paper a new identification algorithm using the single frequency and cumulative observation method was proposed. The simulation result shows that the proposed algorithm with 31 observation and accumulation is more effective and realizable than the NNR with 3 freqnencies when the noise level n is below 0.3.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.36.2-36.2
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• 2016

In mm-VLBI, the quality of observation data is largely affected by atmospheric effect. The most challenging matter is that the phase of correlator output fluctuates rapidly resulting from a variation of atmospheric propagation delay. Consequently, it is demanding to achieve high Signal-to-Noise ratio by integrating data in time domain before calibrating atmospheric delay. However, Korean VLBI Network (KVN) has a unique system to make a 4-frequency (22/43/86/129 GHz) simultaneous observation in mm-wavelength and Frequency Phase Transfer (FPT) calibration technique has effectively removed atmospheric delay in the simultaneous multi-frequency observation of the KVN. For astrometric and astrophysical studies, we evaluated the FPT performance of KVN in various observing conditions. Using the total 38 bright AGNs, we have compared atmospheric conditions such as ground-based weather information, system temperature, atmospheric delay with the calibration results of FPT at 22/43/86/129 GHz during the five experiments in 2013, and quantified its performance in terms of coherence function and Allan variance. We present the analysis result of the relation between the FPT performance and observing conditions.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.349-352
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• 2007

The Fourth Assessment Report of IPCC predicted that global warming is already happening and it should be caused from the increase of greenhouse gases by the extension of human activities. These global changes will give a serious influence for human society. Global environment can be monitored by the earth observation using satellite. For the observation of global climate change and resolving the global warming process, satellite should be useful equipment and its detecting data contribute to social benefits effectively. JAXA (former NASDA) has made a new plan of the Global Change Observation Mission (GCOM) for monitoring of global environmental change. SGLI (Second Generation GLI) onboard GCOM-C (Climate) satellite, which is one of this mission, provides an optical sensor from Near-DV to TIR. Characteristic specifications of SGLI are as follows; 1) 250 m resolutions over land and area along the shore, 2) Three directional polarization observation (red and NIR), and 3) 500 m resolutions temperature over land and area along shore. These characteristics are useful in many fields of social benefits. For example, multi-angular observation and 250 m high frequency observation give new knowledge in monitoring of land vegetation. It is expected that land products with land aerosol information by polarization observation are improved remarkably. We are studying these possibilities by ground data and satellite data.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.617-622
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• 2016

The article describes the determination of the dynamic stability for an observation antenna, considering the rotational speed by the payload driving motor. A finite element model of the observation antenna was made using the solid and beam elements. The connecting parts between the solid and the beam was adequately coupled. The boundary conditions were made by restriction of the degree of freedoms in the supporting points. With the comparison between the modal analysis results and the rotating speed of the payload driving motor, no resonance for the structure of antenna was identified and first natural frequency was determined under 33 Hz (Seismic Cut-Off Frequency). Therefore, the dynamic stability of the antenna was confirmed by the comparism between the seismic safety criterion and the stress results of the dynamic analysis applied the loading conditions and required response spectrum (RRS).

• ETRI Journal
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• v.28 no.3
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• pp.275-281
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• 2006

A very simple and efficient scheme for jitter reduction is proposed for a carrier frequency recovery loop using phase differential frequency estimation, which estimates the current frequency offset based on the difference of the average phases of two successive intervals. Analytical and numerical results presented in this paper show that by simply overlapping the observation intervals by half for frequency offset estimations, both the steady-state and transient performances can be improved. The proposed scheme does not require any additional hardware circuitry, but results in improved performance even with reduced complexity.

• Science of Emotion and Sensibility
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• v.18 no.4
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• pp.3-14
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• 2015

This study has extracted observation data by spatial factor for the analysis of subjects' selective attention with the objects of public space at the entrance of subway stations. The methods extracting observation data can be summarized as the following. First, the frequency analysis by lattice was prevalent for those methods, but there is a limitation to the analysis of the observation data. On the contrary, the method extracting observation data by factor applied in this study can make it clear if any sight is concentrated on any particular factors in a space. Second, the results from the extracted data corresponding to the observation area can be objectified while the method setting up the observation area by applying the radius of fovea. Third, time-sequential trace of observation results of relevant factors was possible through hourly analysis of spatial factors. The consideration of the results of "corresponding spatial scope" which is the object of this study will reveal that the more the observation time, the less the degree of attention it receives. Fourth, the frequency of observation superiority was applied for the analysis of the sections with selective attention by time scope; this revealed that men and women had intensive observation in time scope I (52.4 %) and in time scope IV (24.0 %), respectively.

• English Language & Literature Teaching
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• v.17 no.1
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• pp.17-35
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• 2011

The purpose of this study was to explore the effect of an explicit word instruction for EFL beginning readers and their perception on the learning experience. Data were attained from 16 fourth graders who took English class as a development activity. Data include the results of pre- and post-test of high frequency sight word recognition, oral reading ability, students' survey responses, and teacher observation. The descriptive statistics were obtained for the result of the pre- and post-test. The findings from the student survey and teacher observation were also provided and interpreted to better understand the result of project and students' perception on the learning experience. The followings are the results of this study. The word recognition ability of the students was dramatically improved after the project. The students were satisfied with the overall learning experience perceiving it as helpful and fun learning. They expressed that the explicit word instruction helped their word recognition and reading ability. The results also supported that the confidence of students on their reading ability were heightened. Several suggestions are made for teachers and researchers on the word instruction for young EFL learners who are beginning readers.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.43.2-43.2
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• 2010

Following the success of detecting fringes on KVN (Korean VLBI Network), a phase referencing observation is currently planned in order to achieve a better sensitivity in mm-VLBI. The high frequency observation ($\geq$ 22 GHz), wide bandwidths (~512 MHz) and high speed data recording (~1 Gbps, Mark5B) will result in resolution and sensitivity improvement on KVN. In particular, two powerful techniques of VLBI phase correction by fast-antenna switching and multi-frequency phase referencing are also introduced in KVN, hoping to resolve the problem of atmospheric delay errors which degrade the coherence significantly. In this study, we have compared the expected performance of phase referencing between fast antenna switching and multi-frequency phase referencing and discussed the essential condition and postulates of phase referencing for KVN.