• Journal of Information Technology Applications and Management
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• v.21 no.3
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• pp.1-17
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• 2014

In this study, various characteristics of R&D related economic variables were studied to analyze complexity of science and technology activities in Korea, as reliance of R&D activities of the private sector is growing by the day. In comparison to other countries, this means that it is likely to be fluctuated by economic conditions. This complexity characteristic signifies that the result of science and technology activities can be greatly different from the anticipated results - depending on the influences from economic conditions and the results of science and technology activities which may be unpredictable. After reviewing the results of 17 variables related to science and technology characteristics of complex systems intended for time-series data - in the total R&D expenditure, and private R&D expenditure, numbers of SCI papers, the existence of chaotic characteristics were. using Lyapunov Exponent, Hurst Exponent, BDS test. This result reveals science and technology activity of the three most important components in Korea which are; heavy dependence on initial condition, the long term memory of time series, and non-linear structure. As stable R&D investment and result are needed in order to maintain steady development of Korea economy, the R&D structure should be less influenced by business cycles and more effective technology development policy for improving human resource development must be set in motion. And to minimize the risk of new technology, the construction of sophisticated technology forecasting system should take into account, for development of R&D system.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.392-404
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• 2011

In this paper, we address the issue of joint detection schemes for uplink cellular system when base station cooperation is possible for multi-user detection in multi-cell scenario. The ZF, ML, MMSE and SIC detection are analyzed and evaluated as a conventional scheme. ML attains the optimal performance but the complexity increases exponentially, ZF/MMSE have simple structure but have poor detection performance and SIC has better performance but it has large complexity and potential of the error propagation. However, they need the increased decoder complexity as the number of iteration is increased. We propose a new joint ML and ZF/MMSE detection scheme, which combines the partial ML decoding and ZF/MMSE detection, in order to decrease the decoder complexity. Simulation results show that the proposed scheme attains same or a little bit better BER performance and expect reduced decoder complexity, specially in the case of large number of Base Station are cooperated each other.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.539-546
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• 2010

In next generation wireless communication systems based on OFDM, multiple-input multiple-output (MIMO) technique is adopted in order to achieve high data throughput with limited bandwidth. As one of MIMO techniques, spatial multiplexing scheme needs high performance data detection algorithm that can be performed with low computational complexity. In this paper, we propose an algorithm that can compute QRM-MLD with reduced complexity. Also, hybrid detection technique is proposed, which can reduce the complexity by selecting between MMSE and QRM-MLD according to the channel condition. The proposed algorithm provides the trade-off between performance and complexity. The computer simulations for downlink transmission in 3GPP LTE system show that less than 0.1dB performance degradation can be achieved at 0.1% BER with 59% reduction on computational complexity compared with the conventional QRM-MLD algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.499-506
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• 2012

In this paper, we analyze the effects of phase noise and frequency offset that cause performance degradation. Basically, we like to propose reduced PNFS(Phase Noise and Frequency offset Suppression) algorithm. The OFDM system is seriously affected by ICI component such as phase noise, frequency offset and Doppler effects. Especially, complicated processing algorithm with high complexity was required it in order to compensate those ICI components. So, we propose PNFS algorithm that can decrease complexity and compensate ICI components. We propose a method decreased complexity by approximation of parameters that affect slightly performance change and compare the quantity of conventional and revised PNFS algorithm. Also, simulation shows that BER performance of revised PNFS algorithm can be improved slightly.

• The KIPS Transactions:PartB
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• v.12B no.4 s.100
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• pp.451-458
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• 2005

The transcoding is a solution which is able to adapt to heterogeneous clients of requesting a different playback rate of multimedia data. Thus, The transcoding needs decoding and encoding. In general, previous studies to reduce complexity have a problem, the degradation of visual quality On the contrary, previous studies to reduce the degradation of visual quality lead to heavy computation. Thus, many researchers have studied a solution between the complexity and the degradation of visual quality. But until now, most researches of this region have dealt with the transcoder itself, such researches about a server's assistance to improve the performance of transcoder is rarely studied. In case of servicing multimedia data to heterogeneous clients which have low capabilities, the assistance of server side is able to reduce frames with processing in the transcoder and improve the performance of the transcoder. Thus in this paper, we propose the frame-skipping transcoder system architecture that takes into consideration transcoder and server side to reduce the complexity of the transcoder.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.6
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• pp.1828-1847
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• 2014

Coordinated multi-point (CoMP) transmission has been regarded as a potential technology for LTE-Advanced. In frequency division duplexing systems, channel quantization is applied for reporting channel state information (CSI). Considering the dynamic number of cooperation base stations (BSs), asymmetry feature of CoMP channels and high searching complexity, simply increasing the size of the codebook used in traditional multiple antenna systems to quantize the global CSI of CoMP systems directly is infeasible. Per-cell codebook based channel quantization to quantize local CSI for each BS separately is an effective method. In this paper, the theoretical upper bounds of system throughput are derived for two codeword selection schemes, independent codeword selection (ICS) and joint codeword selection (JCS), respectively. The feedback overhead and selection complexity of these two schemes are analyzed. In the simulation, the system throughput of ICS and JCS is compared. Both analysis and simulation results show that JCS has a better tradeoff between system throughput and feedback overhead. The ICS has obvious advantage in complexity, but it needs additional phase information (PI) feedback for obtaining the approximate system throughput with JCS. Under the same number of feedback bits constraint, allocating the number of bits for channel direction information (CDI) and PI quantization can increase the system throughput, but ICS is still inferior to JCS. Based on theoretical analysis and simulation results, some recommendations are given with regard to the application of each scheme respectively.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.58-64
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• 2016

This paper proposes the efficient transmit antenna selection (TAS) scheme considering trade-off between the performance and the complexity in massive MIMO system. The massive MIMO system is a core technology to achieve performance objectives for 5 generation wireless communication. It achieve high spectral efficiency, a reliability, and a diversity gain. However many RF chains required by massive transmit antennas equipped in a base station create the problem such as high hardware cost and complexity. Therefor we investigates the transmit antenna selection scheme, in which the number of RF chains of BS is reduced, and the trade-off between the performance and the complexity is considered for proposed scheme. And, the spectral efficiency and complexity are analysed by transmit antenna selection schemes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.346-351
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• 2003

In spite of the size and complexity of software becomes large and complicated, the demand of rapid development, cost reduction, good productivity and good quality software is increasing in these days. Many methods were proposed for efficient software development such as various Case tools. Metrics, Process improvement model (CMM, SPICE, ISO9000) and etc. However, most of them we useful to manage the whole projects rather than an individual programming. In this paper, we introduced a system for quality assessment and complexity metrics for Java programs to assess the individual programmer's quality rather than team's quality. This system shows not only the metrics value for quality assessment but also the source code and the soucture of classes simultaneously.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.1-7
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• 2006

This paper proposes a new method that reduces the complexity of the combined system, which consists of the selective mapping(SLM) and the partial transmit sequence(PTS) in the Orthogonal Frequency Division Multiplexing(OFDM). In order to reduce the Peak-to-Average Power Ratio(PAPR), many techniques have been developed such as SLM and PTS. and their combined systems. However the method that simply combines PTS and SLM to improve the effectiveness of a system increases the complexity of calculation. The scheme employed in this research suggests a system that combines PTS and SLM reducing the complexity via the N($N=2^n$)-point inverse fast Fourier transforms(IFFT), which uses the decimation in time domain not only to improve PAPR but also to reduce the amount of calculation. The proposed method reduces the complexity by multiplying a phase sequence and a subblock index to the data sequences in the middle of IFFT, which yields an optimal sequence with minimal PAPR. The superiority of the proposed method is demonstrated by simulation results and analysis.

• Asia pacific journal of information systems
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• v.10 no.3
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• pp.41-59
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• 2000

The role of information systems(IS) is far more important in business operations today. Managers recognize information as a major resource of the organization, and non-expert end users positively participate in information system development processes. This phenomenon is considered user-led information system development(ULD), where users define the information requirements, oversee system testing, manage system development, and lead the overall project. Based on a socio-technical approach, this study examines the impact of ULD on IS success. This paper also investigates the moderating effects of various contextual factors on the relationships between ULD and the success. The questionnaire was developed and the data was collected from the end users who participated in implementing ERP systems. The results showed that ULD positively affects the success. For the moderating variables, IT complexity was found to have a strong effect on the relationship between ULD and the success while business complexity and top management support have partial effects. Surprisingly, resource adequacy was not found to have the effect. This study provides academia and practitioners with a number of implications and guidelines regarding why and when to introduce ULD in their IS development initiatives.