• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.303-308
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• 2001

An objection of this study is to develop a high stable measuring circuits and a analytic system for radioactive pulses. The proposed system consists of a pulse detection units for neutrons and gamma-rays a programmable high voltage supply unit and a digital signal processor. The programmable high voltage supply unit designed can generate DC voltage up to 1,500 V at 5 V input and have a series voltage regulator to maintain the output voltage constantly, resulting in less than 1.63% of voltage regulation. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60 dB, and its frequency bandwidth is from 37 Hz to 300 kHzAlso, pulse height distribution in accordance with pulse counts is important data in analyzing radioactive pulses. In this study, A/D convertor (12bit, 100ms) and DSP (TMS320C31-60) are used to analyze the pulse height, and the analytic system is designed to be operated in PC-base.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.5
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• pp.478-491
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• 1987

In this paper, an all Digital Phase-Locked Loop(DPLL) has been propoed, which has reduced the phase error by using a half period sampling in order to improve the performance of the conventional DPLL which tracks the phase of incoming sinusoidal signal once per cycle for the Positive Going Zero crossing(PGZC) of the signal. The proposed DPLL tracks the phase of input signal twice per cycle with two samplers for the PGZC. So the loop has a half reduction of the steady state phase error fluctuation ranges without decreasing the lock-range in a whole, comparing with that of the conventional DPLL. Also, it has been known that the proposed loop is rapidly locked to input signal for the same valves of phase differenc between sucessive samples and quantization level. The analytic results of the proposed loop have been verified by computer simulation for the practically requeired conditions.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.95-100
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• 2005

This paper proposes a DVS method which effectively reduces the power consumption of multimedia signal processor. Analytic derivations of effective range of its power saving factor are obtained with the assumption of a Gaussian distribution for the frame-based computational burden of the multimedia processor. A closed form equation of the power saving factor is derived in terms of the mean-standard deviation of the distribution. An MPEG-2 video decoder algorithm and AAC encoder algorithm are tested on ARM9 RISC processor for the experimental verification of the power saying of the proposed DVS approach. The experimental results with diverse MPEG-2 video and audio files show 50～30% power saving factor and show good agreement with those of the analytically derived values.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.28-38
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• 1997

Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.165-169
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• 2004

Marine magnetic survey were carried out at Sokotra Basin offshore Korea between latitudes $31^{\circ}$ 42'32' N and $32^{\circ}$ 46'29' N, and longitudes $123^{\circ}$ 56'26" E and $125^{\circ}$ 49'16" E in order to estimate the depth of basement complex and as well as to configure it surface and produce the thickness of sedimentary sequence at the study area. Two methods have been used for depth estimation and basement configuration: the power spectrum and the 3-D analytical signal. The estimated depths resulted from the power spectrum method range from 1.4 km to 6.0 km for deep sources (basement troughs), and from 0.3 km to 1.75 km for shallow source (basement peaks). An isopach map was prepared for estimating the thickness of the sedimentary sequence at the study area; it ranges from 1.2 to 4.66 km. The estimated depths resulted from the analytic signal method range from 1.0 to 6 km. A basement configuration map was constructed for the study area in the basin. They show a well agreement with the geology of the study area.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.66-71
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• 2009

In view of mutual complementary feature of wide coverage and high data rate, the interworking between 3G cellular network and WLAN is a global trend of wireless communications. This paper introduces the analytic result of an authentication mechanism for 3GPP-WLAN seamless mobility under the USIM-based authentication test-bed. In a handover process between heterogeneous networks, authentication is the main factor of handover delay. So authentication processing time should be firstly reduced. This paper describes an USTM-based EAP-AKA test-bed implemented for handover in UMTS and WLAN interworking systems. Experimental result has shown that the fast re-authentication mechanism during handover has reduced the handover delay by about 48.6%.

• Journal of Korean Society for Quality Management
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• v.41 no.2
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• pp.301-322
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• 2013

Purpose: This study aims to determine the needs of customers who use railroads as a mode of transportation and propose customer-oriented improvements in railroad technology by making connections between customer needs and railroad technology. Methods: We primarily used two methods for this study, AHP and QFD. First, AHP was used to evaluate the relative importance among the different components of railroad technology. Second, the QFD was applied to make a link between customer needs and railroad technology. Results: Railroad technology is largely divided into development, maintenance, and support. Empirical results showed the following improvement priorities in development, vehicle, system, line, signal/communication, power, and structure, in maintenance, vehicle, signal/communication, line, process, power, and structure, and in support, safety/precaution, management, environmental energy, operations/logistics, and station. Conclusion: Recognizing limitations in measuring the level of railroad technology when using the existing 'Technology Growth Model,' we used AHP and QFD to explore improvement directions for customer-oriented railroad technology. By offering customer-oriented services based on this study, railroad service providers will be able to acquire competitive advantage in the market.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2C
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• pp.99-104
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• 2011

The chirp spread spectrum (CSS) technique spreads the data signal over a frequency bandwidth wider than minimum required bandwidth. By using time overlapping, the bit rate in CSS can be increased. However, for reliable transmission of data signal, the intersymbol interference (ISI) due to overlap should be analyzed. In this paper, the relation between the degree of overlap and ISI is analyzed in direct modulation binary phase shift keying CSS systems. In some cases, the overlap does not incur ISI at all and the ISI fluctuates or monotonically increases as the number of overlaps changes. It is also shown that the simulation results closely agree with the analytic results.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.394-400
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• 2018

Various numerical methods have been adopted for indoor noise assessments of ship plant. Acoustical radiosity method is one of the high frequency approaches for acoustic field analysis, which assumes diffuse reflections by boundaries so that it could be efficiently applied to the acoustically diffused indoor space noise analysis. In this study, an acoustic field analysis program has been developed based on radiosity method, which could apply for acoustically large enclosures such as ship's indoor space. For this purpose, the procedure of the acoustical radiosity method has been summarized and implemented to an acoustic field analysis program using MATLAB. Numerical example for a rectangular indoor space has investigated validity of the implemented program. Steady state sound pressure levels calculated for a continuous acoustic source signal have shown good agreement with those by other solutions such as an analytic solution and a ray tracing method. Instantaneous sound pressure levels calculated for an impulsive acoustic signal have provided the clues of direct/reflected acoustic field and reverberation time.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.109.1-109.1
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• 2012

In the past few years, two-planet circumbinary systems (e.g., HW Vir, NN Ser, DP Leo and HU Aqr) have been detected around short-period eclipsing binaries using ground-based telescopes. The existence of these planets has been inferred by interpreting the O-C variations of the mid-eclipse times. We have tested the orbital stability of these systems and propose to use Light Travel Time Effect (LITE) to detect such circumbinary planets from the ground. We generated synthetically the LITE signal of a two-planet circumbinary system with the aim to apply an analytic LITE model to recover the underlying synthetic system. To mimic a degree of realism inherent to ground-based observations, we added to the synthetic LITE data white noise with a Gaussian distribution and sampled the synthetic LITE signal randomly. We successfully recovered the original system demonstrating that two-planet circumbinary systems can be detected using ground-based telescopes, provided the timing measurements of the mid-eclipses are sufficiently accurate and the observing baseline is long enough to ensure a sufficient coverage of all involved periods. We used HU Aqr as a test system and applied our model to its proposed planetary bodies considering near-circular orbits. We present the results of our calculations and discuss the LITE-detectability of a HU Aqr-like system.