• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.189-199
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• 2007

In this paper, we describe the proposed KVN (Korean VLBI Network) clock system in order to make the observation of the VLBI effectively. In general, the GPS system is widely used for the time information in the single dish observation. In the case of VLBI observation, a very high precise frequency standard is needed to perform the observation in accordance with the observation frequency using the radio telescope with over 100km distance. The objective of the high precise clock system is to insert the time-tagging information to the observed data and to synchronize it with the same clock in overall equipments which used in station. The AHM (Active Hydrogen Maser) and clock system are basically used as a frequency standard equipments at VLBI station. This system is also adopted in KVN. The proposed KVN clock system at each station consists of the AHM, GPS time comparator, standard clock system, time distributor, and frequency standard distributor. The basic experiments were performed to check the AHM system specification and to verify the effectiveness of implemented KVN clock system. In this paper, we briefly introduce the KVN clock system configuration and experimental results.

• Korean Institute of Interior Design Journal
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• v.16 no.2 s.61
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• pp.131-138
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• 2007

Relationship between body and space is fundamental in space design. The perception and concept of human body in each age directly affected the space makings of that time. Thoughts on human body are related to various periodical backgrounds such as culture, art, technology and etc. Body-Space relationship has been changed through different epochs and is being changed in the present time too. In contemporary cities, architectural programs has been fragmented and activities of individuals become more articulated. The rigidity of each architectural program has been forced to be more flexible amalgamation of diverse behaviors by dynamic urban time-space formations and patterns. Based on this current situations, new experimental designs that question the existing preconceived relationship between body and space in different views. These design experiments attempt to overcome the solid physical fixation of architectural buildings and to directly relate human body to intelligent devices, technologies, machines as well as spaces. This research focus on the innovative design projects in which body, machine, space are smartly compound as one organization. The purpose of this study is to examine the new Body-Space relationship as well as some relevant case projects in contemporary fashion, furniture, interior design and architecture.

• ETRI Journal
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• v.26 no.6
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• pp.565-574
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• 2004

Differential unitary space-time modulation (DUSTM) has emerged as a promising technique to obtain spatial diversity without intractable channel estimation. This paper presents a study of the application of DUSTM on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with frequency-selective fading channels. From the view of a correlation analysis between subcarriers of OFDM, we obtain the maximum achievable diversity of DUSTM on MIMO-OFDM systems. Moreover, an efficient implementation strategy based on subcarrier reconstruction is proposed, which transmits all the signals of one signal matrix in one OFDM transmission and performs differential processing between two adjacent OFDM blocks. The proposed method is capable of obtaining both spatial and multipath diversity while reducing the effect of time variation of channels to a minimum. The performance improvement is confirmed by simulation results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.87-90
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• 2007

In cooperative communication systems, the source terminal transmits signal to the destination terminal with the aid of partner terminals. Therefore, the source terminal obtains extra spatial diversity gain. As a result, its performance is enhanced in term of higher achievable transmission rate, the larger coverage range, and the lower bit-error-rate (BER). Space-time codes (STCs) have been applied to cooperative communication systems in distributed fashion, in which the signal is spatially time exploited to obtain gains analogous to those provided by STCs. In this work, we consider the application of orthogonal Space-time Block Codes (OSTBCs) to the cooperative communication systems to further achieve higher diversity gain. The advances of the proposed approach are verified via computer simulations.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.281-292
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• 2014

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closed-loop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.

• Journal of the Korea Society for Simulation
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• v.13 no.2
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• pp.1-12
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• 2004

This paper estimated the arrival angle and electric wave delay time using the space method law and the directions of arrival (DOA) estimation algorithm in case of signal correlation. Space method law is the method used to repress cross correlation before applying the weight value to the receiving signal. The values of the diagonal elements in the correlation matrix were averaged to replace as the diagonal elements value. In the area of wireless communication or mobile communication, there are high correlations in case of low delay time difference in multiple waves. This causes the quality of the communication to drop due to interference with the desired signal elements. This paper estimated the arrival angle and electric wave delay time using the space method law and the MUSIC algorithm. With the arrival angle algorithm, the arrival angle cannot be estimated below 5 in case of signal correlations because the angle resolution capacity decreases accordingly. The super resolution capacity was estimated to determine the arrival angle below 5 in this paper. In addition, the proposed algorithm estimated the short delay time difference to be below 20ns.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.715-718
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• 2016

SpaceWire invented for on-board data handling in a spacecraft has Time-Code defined for time synchronization over SpaceWire network. Delay and jitter of the transmission of Time-Code caused when a Time-Code travels through a network are the main reasons of time synchronization error. This work proposes a scheme that can reduce the time synchronization error by using extended Time-Codes. The proposed scheme can remove both transmission jitter and transmission delay. The scheme will be validated in a simulation environment built with OMNeT++.

• Korean Institute of Interior Design Journal
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• v.22 no.3
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• pp.91-99
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• 2013

It is easier to objectify the designing process with the analysis of how users perceive any space depending on the purpose of space visiting in the interactions of them and images. This study analyzed the observation characteristics perceived through observation frequency and time depending on the purpose cafe customers to understand what effect the design factors constructing the space has on the observation characteristics which are the results obtained as information through visual perception. The followings are the results of this study. First, The time range for searching or wandering and the observation characteristics could be estimated by the meaning of observation time by grade with the setup of time-range out of the distribution of sections. Second, at the time distribution by section, when there was intention, the observation time was found to have higher occupation. Third, though the higher section frequency is likely to have more observation time, the grades of II/V had higher frequency of [Intention] and the time had higher [Non-Intention], which revealed that there is a tendency for the observation characteristics vary in a large degree depending on whether there was intention or not. Fourth, by the application of the observation characteristics of each grade for interrelation analysis depending on whether there is any intention to the space of cafe, the detailed space characteristics could be compared with observation tendency. The difference of obtained information has an effect on obtaining perceived information, and since the intention may affect any information which is obtained, it is necessary for design information suitable to visit purpose or users' observation intention to be transferred in the process of designing. Analyzing the effect of any change to designing factors on the sight inducing intention and synchronization will help to understand the emotional design focused on users.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.11a
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• pp.84-88
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• 2007

Movie has a light, colors, and texture in the space and a design. Movie is a ovation of the 3-dimensional reality with time and space. Just like a movie, a space can also express time, personality of characters and background stories. Symbolization of a space tells philosophy and emotions, making meaning of the space abundant and consistency in entire composition of the space. Expression of beauty through order of space inside proves meaning of space. Think that can do and present to production methodology of space design to universalize ureas through symbolic productions that is based on story.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.58.1-58.1
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• 2019

We have developed Ground Software (GSW) of BITSE. The ground software includes mission operation software, data visualization software and data processing software. Mission operation software is implemented using COSMOS. COSMOS is a command and control system providing commanding, scripting and data visualization capabilities for embedded systems. Mission operation software send commands to flight software and control coronagraph. It displays every telemetry packets and provides realtime graphing of telemetry data. Data visualization software is used to display and analyze science image data in real time. It is graphical user interface (GUI) and has various functions such as directory listing, image display, and intensity profile. The data visualization software shows also image information which is FITS header, pixel resolution, and histogram. It helps users to confirm alignment and exposure time during the mission. Data processing software creates 4-channel polarization data from raw data.