• Bulletin of the Korean Space Science Society
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• 2002.10a
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• pp.32.2-32
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• 2002

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.570-570
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• 2006

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.215-224
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• 2001

We present the whole basis of numerical method and useful formulae for general relativistic magnetohydrodynamic simulations in Kerr space-time.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.2
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• pp.45-51
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• 2000

This study proposes that analysis and evaluation method of time series ultrasonic signal using the chaotic feature extrac-tion for degradation extent. Features extracted from time series data using the chaotic time series signal analyze quantitatively material degradation extent. For this purpose analysis objective in this study if fractal dimension lyapunov exponent and strange attractor on hyperspace. The lyapunov exponent is a measure of the rate at which nearby trajectories in phase space diverge. Chaotic trajectories have at least one positive lyapunov exponent. The fractal dimension appears as a metric space such as the phase space trajectory of a dynamical syste, In experiment fractal(correlation) dimensions and lyapunov experiments showed values of mean 3.837-4.211 and 0.054-0.078 in case of degradation material The proposed chaotic feature extraction in this study can enhances ultrasonic pattern recognition results from degrada-tion signals.

• Journal of electromagnetic engineering and science
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• v.18 no.1
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• pp.58-62
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• 2018

In this study, we propose a software-defined radio-based frequency interference emulator in the space-time domain. This emulator can easily model actual interference environments because of the versatile programming capability of the universal software radio peripheral and LabVIEW. As an example of an interfering network using the contention-based multiple access scheme in the time domain, we emulate a coordinated Wi-Fi network that consists of one access point and two Wi-Fi nodes. Results show that our emulator can successfully model multiple interfering signals in the Wi-Fi network and easily adjust various space-time domain parameters.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.334-343
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• 2017

The optimum design of an SAR (Synthetic Aperture Radar) satellite constellation is developed herein using a genetic algorithm. The performance of Earth observations using a satellite constellation can be improved by minimizing the maximum revisit time. Classical orbit design using analytic methods has limitations when addressing orbit dynamics due to various disturbances. To overcome this issue, an optimization technique based on a genetic algorithm is used. STK (Systems Tool Kit) is utilized to propagate the satellite orbit when considering external disturbances, and the maximum revisit time on the earth observation area is calculated. By minimizing the performance index using a genetic algorithm, the optimum orbit of the satellite constellation is designed. Numerical results are provided to demonstrate the performance of the proposed method.

• Journal of Korean Medical classics
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• v.11 no.1
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• pp.2-20
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• 1998

In the field of acupuncture and moxibustion, the theory of taboo of acupuncture and moxibustion on the basis of where the 'Qi and the soul of the men(人氣 人神)' exist became the foundation of the 'theory of chrono-acupunclure and moxibustion(時間性鍼灸法), that takes into account the thrift and retreatment of the Qi(氣) and the 'soul of the men' according to day and time. The fields of acupuncture and moxibustion in the theory of 'Yun Qi(運氣) which takes into account time space are the theories of the 'ZiWuLinZhu(子午流注)' and the 'LingGuiBaFa(靈龜八法)'. While the theory of the 'ZiWuLlnZhu' has the nature of time, 'LingGuiBaFa' has the nature of space comparatively. So the theory of 'Yun Qi' adopted and improved the time-space background that is the basis of the theory of the 'ZiWuLinZhu' and the 'LingGuiBaFa'.

• Journal of the Korean housing association
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• v.14 no.1
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• pp.1-10
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• 2003

The purpose of this study is to analyze patterns of space use and housing preferences to be used in the housing plan for students. Data was collected through questionnaire surveys from local university students living apart from their family. We collected 272 samples and analyzed them using SPSSwin program. The results are as follows; 1) The average hours of staying at the housing for student are 5 hours and 30 minutes(except sleeping time). Most of the time was used for ‘hobby’ and ‘study\ulcorner computer works’. The most of the students had ‘a meal per day’ at their housing. 2) The most preferred housing type by the students is ‘studio apartment’ and the next preferred is ‘apartment’. The highly demanded facility is ‘laundry’ and the next comes ‘kitchen’. 3) Those who spend more time in their housing than average show higher demand in ‘kitchen’ and ‘balcony’. Those who spend less time in their housing show higher demand in ‘storage’.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.628-638
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• 2005

The analysis of maximum diversity order and coding gain for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems over time-and frequency-selective (or doubly-selective) channels is addressed in this paper. A novel channel time-space correlation function is developed given the spatially correlated doubly-selective Rayleigh fading channel model. Based on this channel-model assumption, the upper-bound of pairwise error probability (PEP) for MIMO-OFDM systems is derived under the maximum likelihood (ML) detection. For a certain space-frequency code, we quantify the maximum diversity order and deduce the expression of coding gain. In this wort the impact of channel time selectivity is especially studied and a new definition of time diversity is illustrated correspondingly

• The Korean Journal of Applied Statistics
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• v.17 no.3
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• pp.403-418
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• 2004

Recently space-time model in spatial data analysis is widly used. In this paper we applied this model to analysis of greenhouse whitefly. For handling time component, we used ARMA model and autoregressive error model and for outliers, we adapted Mugglestone's method. We compared space-time models and geostatistic model with MSE and MAPE.