• The Journal of Society for e-Business Studies
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• v.19 no.1
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• pp.95-118
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• 2014

The information technologies industry is now experiencing a rebirth of strong stable growth. However, very few studies have examined performance implications of strategic alliance or merger and acquisition from a knowledge-based view. Furthermore, none of these studies have investigated resource complementarities and alliance or merger and acquisition motive as potential sources of firm performance. This paper extends upon current knowledge-based literature to discover and explore linkages between resource complementarities and firm performance of strategic alliances or merger acquisitions. This study finds that strategic alliance and merger and acquisition announcements have provided abnormal positive returns of production alliances and merger and acquisition. This study can be used as a stepping stone for selection of strategic alliance or merger and acquisition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.983-990
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• 2008

In communication systems, initial acquisition is required for the reliable transmission performance, and the analysis of the acquisition performance over various communication environments including different signal-to-noise ratios plays an important role in communication system design. Usage of differential correlation methods in initial synchronization procedure is desired when frequency offsets exist, and additional performance improvement can be achieved through proper modifications of conventional correlation schemes. In this paper, we derive the error probability of the initial acquisition and express it in terms of the Marcum Q-function, via statistical modeling of the differential correlator output. The result is generalized to the error probabilities of the extended differential correlation methods using the complex- and magnitude-sum of the correlator outputs. The derived probabilities can be applied for the acquisition performance verification of various communication systems including the DVB-S2 standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.467-473
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• 2014

In the direct sequence spread spectrum system, the correct synchronization is very important; hence, several acquisition schemes based on the sequential estimation have been developed. Typically, the rapid acquisition sequential estimation (RASE) scheme, the seed accumulating sequential estimation (SASE) scheme, the recursive soft sequential estimation (RSSE) scheme have been developed for the correct acquisition. However, the objective performance comparison and analysis between former estimation schemes have not been performed so far. In this paper, we compare and analyze the performance of the above sequential estimation schemes by simulating the correct chip probability and the mean acquisition time (MAT).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.851-858
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• 2012

In this paper, we design a seismic data acquisition system(SDAS) and implement it. This system is essential for development of a noble local earthquake disaster preventing system in population center. In the system, we choose a proper MEMS-type triaxial accelerometer as a sensor, and FPGA and ARM processor are used for implementing the system. In the SDAS, each module is realized by Verilog HDL and C Language. We carry out the ModelSim simulation to verify the performances of important modules. The simulation results show that the FPGA-based data acquisition module can guarantee an accurate time-synchronization for the measured data from each axis sensor. Moreover, the FPGA-ARM based embedded technology in system hardware design can reduce the system cost by the integration of data logger, communication sever, and facility control system. To evaluate the data acquisition performance of the SDAS, we perform experiments for real seismic signals with the exciter. Performances comparison between the acquired data of the SDAS and the reference sensor shows that the data acquisition performance of the SDAS is valid.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.682-688
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• 2006

In this paper, a soft-decision method for initial PN code acquisition in pilot-channel aided Direct Sequence Code Division Multiple Access (DS-CDMA) systems is proposed in order to improve the acquisition performance. We apply this technique to the conventional hybrid search algorithm and analyze it in terms of mean code acquisition time. For the analysis, we present mathematical model of proposed algorithm and also perform the simulation under IMT-2000 channel models. Numerical results show that our proposed scheme outperforms the conventional one by 0.2 - 0.4 sec with respect to the mean code acquisition time because the soft decision technique can mitigate the possible decline in search performance caused by the use of a hard-decision technique.

• Journal of Astronomy and Space Sciences
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• v.36 no.2
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• pp.97-103
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• 2019

An automated signal-acquisition method for the NASA's space geodesy satellite laser ranging (SGSLR) system is described as a selection of two system parameters with specified probabilities. These parameters are the correlation parameter: the minimum received pulse number for a signal-acquisition and the frame time: the minimum time for the correlation parameter. The probabilities specified are the signal-detection and false-acquisition probabilities to distinguish signals from background noise. The steps of parameter selection are finding the minimum set of values by fitting a curve and performing a graph-domain approximation. However, this selection method is inefficient, not only because of repetition of the entire process if any performance values change, such as the signal and noise count rate, but also because this method is dependent upon system specifications and environmental conditions. Moreover, computation is complicated and graph-domain approximation can introduce inaccuracy. In this study, a new method is proposed to select the parameters via a conditional equation derived from characteristics of the signal-detection and false-acquisition probabilities. The results show that this method yields better efficiency and robustness against changing performance values with simplicity and accuracy and can be easily applied to other satellite laser ranging (SLR) systems.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.69-72
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• 2005

In this paper, pseudo noise (PN) code acquisition performance with multiple antennas in a UWB time hopping/code division multiple access system is analyzed. The closed form for the conditional probability is derived, using the Gauss-Hermite quadrature formula, when the signal with Gaussian distribution goes through the lognormal fading channel. The performance comparison of the above mentioned schemes shows that the code acquisition performance with a diversity combining technique, especially when increasing the number of antennas, is more robust than that using no diversity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.1
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• pp.104-115
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• 1997

This paper investigates PN code acquistion algorithm and demodulation performance of the RAKE receiver in the DS/CDMA(direct sequence code division multiple access) sysytems under a multipath fading channel with multiusers. To speed up the acquisition process, PN matched filter is applied and postdetection integration technique comable withthe dynamic threshold set method is proposed. the Maximum-Likelihood algorithmin serial fashion is able to find PN code delay estimates for the RAKE branches using sliding window in a multipath fading channel. The correct acquistion probability and mean acquistion time are used as a performance measure of the system using the Monte Carlo method. The performance of the RAKEreceiver, afte the code acquisition is achieved is the CDMA systems, is also investigated for three major combining techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.898-908
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• 2004

In this paper, we propose a high speed preamble searcher feasible for RACH(Random Access Channel) preamble structure in WCDMA reverse link receiver. Unlike IS-95, WCDMA system uses AISMA(Acquisition Indication Sense Multiple Access) process. Because of the time limit between RACH preamble transmission and AI(Acquisition Indicators), and the restriction on the number of RACH signatures assigned to RACH preamble, fast acquisition indication is required for efficient operation. The preamble searcher proposed in this paper is based on 2-antenna system and has adopted FHT algorithm that has the radix-2 16 point FFT structure. The acquisition speed using FHT is 64 times faster than the conventional method that correlates each signature. Based on their fast aquisition scheme, we improved the acquisition performance by calculating the correlation up to the 4096 chips of the total preamble length. The performance is analyzed by using Neyman-pearson method. The proposed algorithm has been applied for the implementation of WCDMA reverse link receiver modem successfully.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.723-730
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• 2000

In this paper, we perform a performance analysis of serial acquisition scheme using AWGN rejection filter in Rayleigh fading channel and propose robust acquisition scheme using Reference filter, which is utilized to vary threshold at fading rate, in Rayleigh fading channel. AWGN rejection filter is utilized to evaluate running average for compensating channel gain. The JAKE model, which a channel model, is used for the analysis. The simulation result shows that the mean acquisition time of the proposed acquisition system is minimized than acquisition system using AWGN rejection filter and serial-search acquisition system.