• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.939-947
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• 2010

The LDPC(Low-Density Parity-Check) code, which is one of the channel encoding methods in IEEE 802.11n wireless LAN standard, has superior error-correcting capabilities. Since the hardware complexity of LDPC decoder is high, it is very important to take into account the trade-offs between hardware complexity and decoding performance. In this paper, the effects of LLR(Log-Likelihood Ratio) approximation on the performance of MSA(Min-Sum Algorithm)-based LDPC decoder are analyzed, and some optimal design conditions are derived. The parity check matrix with block length of 1,944 bits and code rate of 1/2 in IEEE 802.11n WLAN standard is used. In the case of $BER=10^{-3}$, the $E_b/N_o$ difference between LLR bit-widths (6,4) and (7,5) is 0.62 dB, and $E_b/N_o$ difference for iteration cycles 6 and 7 is 0.3 dB. The simulation results show that optimal BER performance can be achieved by LLR bit-width of (7,5) and iteration cycle of 7.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.85-95
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• 2004

As the design complexity increases, it is a major problem that the size of test pattern is large and power consumption is high in scan, especially system-on-a-chip(SoC), with the automatic test equipment(ATE). Because static compaction of test patterns heads to higher power for testing, it is very hard to reduce the test pattern volume for low power testing. This paper proposes an efficient compression/decompression algorithm based on run-length coding for reducing the amount of test data for low power testing that must be stored on a tester and be transferred to SoC. The experimental results show that the new algorithm is very efficient by reducing the memory space for test patterns and the hardware overhead for the decoder.

• Journal of Information Technology Services
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• v.14 no.2
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• pp.129-142
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• 2015

The purpose of this study is to suggest an effective regression testing method in order to minimize the scope of test resulting from the modification of software and to prevent mismatch of test case and test objects. As a way to improve the efficiency of regression testing which uses a change-centric testing technique, the method flow is analyzed and grasped through a static analysis based on source code in order to identify modified parts. After the order of priority is set according to the results of user action log-based dynamic analysis on identified regression testing objects, test effect can be raised by adjusting the order of priority using code complexity. Quality assurance coverage can be checked using the user action log suggested in this study, and the progress of test and whether or not each function has been verified can be checked, too. In addition, by minimizing test parts and adjusting the order of test, costs and time can be saved, making it possible to conduct regression testing effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.64-68
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• 2005

Reed-Solomon code is one of the most versatile channel codes. The encoder can be implemented with two famous structures: ordinary and bit-serial. The ordinary encoder is generally known to be complex and fast, while the bit-serial encoder is simple and not so fast. However, it may not be true for a longer codeword length at least in VHDL implementation. In this letter, it is shown that, when the encoder is implemented with VHDL, the number of logic gates of the bit-serial encoder might be larger than that of the ordinary encoder if the dual basis conversion table has to be used. It is also shown that the encoding speeds of the two VHDL implemented encoders are exactly same.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.160-165
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• 2003

The design and implementation of an engine control system has become an important area in developing a new car, but the implementation of an engine control system is becoming a tedious and time-consuming work as the level of complexity increases. In order to shorten the development cycle of the control system, rapid control prototyping (RCP) technique deserves developers' attention. A new RCP platform has been developed for an automotive engine control application. This prototyping system strictly adheres to the layered architecture of the final production ECU, and separates the automatically generated part of software, or the application area, from the hand coded area, which generally carefully designed and tested because of the hardware dependency and the efficiency of microcontroller. The $Matlab{\circledR}$ tool-chain of Mathworks Inc. has been selected as a base environment in this study. A newly developed Engine Control Toolbox of Real-Time $Workshop{\circledR}$ converts a graphically represented control algorithm into optimized application codes and links them with other parts of the software to generate executable code for the target processor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.4B
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• pp.427-436
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• 2001

RS product codes are widely used in digital storage systems. There are lots of decoding strategies for product code for short-length RS codes. Unfortunately many of them cannot be applied to long-length RS product codes because of the complexity of decoder. This paper proposes new decoding strategies which can be used in long length RS product codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.20-25
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• 2006

In this paper, the performance of Tree-LDPC code is presented based on the min-sum algorithm with scaling and the asymptotic performance in the water fall region is shown by density evolution. We presents that the Tree-LDPC code show a significant performance gain by scaling with the optimal scaling factor which is obtained by density evolution methods. We also show that the performance of min-sum with scaling is as good as the performance of sum-product while the decoding complexity of min-sum algorithm is much lower than that of sum-product algorithm. The Tree-LDPC decoder is implemented on a FPGA chip with a small interleaver size.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.12
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• pp.465-472
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• 2019

Today, in many area the rise of software necessity there has been increasing the issue of the impotance of Good Software. Our reality in software industrial world has been happening to frequently change requirements at any stage of software life cycle. Furthermore this frequent changing will be increasing the design complexity, which will result in being the lower quality of software against our purpose the original design goals. To solve this problem, we suggest how to improve software design through refactoring based on reverse engineering. This is our way of diverse approaches to visually identify bad smell patterns in source code. We expect to improve software quality through refactoring on even frequently changing requirements.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.2
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• pp.23-33
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• 2009

The inherent aeromechanical complexity of a rotor system necessitated the comprehensive analysis code for helicopter rotor system. In the present study, an aerodynamic analysis module has been developed as a part of rotorcraft comprehensive program. Aerodynamic analysis module is largely classified into airload calculation routine and inflow analysis routine. For airload calculation, quasi-steady analysis model is employed based on the blade element method with the correction of unsteady aerodynamic effects. In order to take unsteady effects - body motion effects and dynamic stall - into account, aerodynamic coefficients are corrected by considering Leishman-Beddoes's unsteady model. Various inflow models and vortex wake models are implemented in the aerodynamic module to consider wake induced inflow. Specifically, linear inflow, dynamic inflow, prescribed wake and free wake model are integrated into the present module. The aerodynamic characteristics of each method are compared and validated against available experimental data such as Elliot's induced inflow distribution and sectional normal force coefficients of AH-1G. In order to validate unsteady aerodynamic model, 2-D unsteady model for NACA0012 airfoil is validated against aerodynamic coefficients of McAlister's experimental data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.729-739
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• 1994

In a centralized spread-spectrum packet radio network, a random assignment -transmitter-based spreading code protocol(RA-T) is proposed which permits the contention mode only in the trasmission of a preamble while avoiding collision during the data packet transmission by assigning near-orthogonal spreading codes to each user. Compared to the conventional transmitter-based code scheme, this scheme allows reduction in receiver complexity when only a small number of distinct spreading codes are employed for the preamble transmission. Throughout theoretical and simulation results, it is shown that the use of the RA-T scheme with just two or three distinct codes for the preamble packet achieves most of the performance gain.