• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.65-68
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• 2000

In CDMA, the currently used PN code acquisition methods detect the phase of the incoming PN signal on the basis of ML estimation. In serial search strategy, it takes relatively long time for PN code acquisition. A study related to reduce processing time of PN code acquisition is important. Therefore we propose a reference code design for a new algorithm that a reference code and the received PN code are fully correlated to detect the transmitted PN code, in detail, the relative phase offset j of c⒡. After choosing two weight factors, we show the mathematical analysis and derivation for the reference code design.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.133-136
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• 2000

A RVLC(Reversible Variable Length Code) with an efficient table memory is proposed in this paper. In the conventional decoding methods, the weight of symbols and code values are used for the decoding table. These methods can be applied for Huffman decoding. In VLC decoding, many studies have been done for memory efficiency and decoding speed. We propose an improved table construction method for general VLC and RVLC decoding, which uses the transition number of bits within a symbol with an enhanced weight decomposition. In this method, tile table for RVLC decoding can be implemented with a smaller memory

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4280-4295
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• 2022

In this paper, a new multi-group neutron-gamma transport calculation code system STRAUM-MATXST for complicated geometrical problems is introduced and its development status including numerical tests is presented. In this code system, the MATXST (MATXS-based Cross Section Processor for S_N Transport) code generates multi-group neutron and gamma cross sections by processing MATXS format libraries generated using NJOY and the STRAUM (S_N Transport for Radiation Analysis with Unstructured Meshes) code performs multi-group neutron-gamma coupled transport calculation using tetrahedral meshes. In particular, this work presents the recent implementation and its test results of the Krylov subspace methods (i.e., Bi-CGSTAB and GMRES(m)) with preconditioners using DSA (Diffusion Synthetic Acceleration) and TSA (Transport Synthetic Acceleration). In addition, the Krylov subspace methods for accelerating the energy-group coupling iteration through thermal up-scatterings are implemented with new multi-group block DSA and TSA preconditioners in STRAUM.

• Journal of computational fluids engineering
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• v.16 no.2
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• pp.30-48
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• 2011

A three-dimensional thermal-hydraulic code, CUPID, has been developed for the analysis of transient two-phase flows at component scale. The CUPID code adopts a two-fluid three-field model for two-phase flows. A semi-implicit two-step numerical method was developed to obtain numerical solutions on unstructured grids. This paper presents an overview of the CUPID code development and assessment strategy. The governing equations, physical models, numerical methods and their improvements, and the systematic verification and validation processes are discussed. The code couplings with a system code, MARS, and, a three-dimensional reactor kinetics code, MASTER, are also presented.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.221-224
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• 2001

A new code: LS code was proposed for IMT-2000 CDMA system. The code has special properties during a certain time of interval: 1) perfect autocorrelation 2) perfect crosscorrelation. The perfect autocorrelation means that the autocorrelation has nMaximum for zero time-offset and zero for other times during a certain time. Moreover the perfect crosscorrelation means that the crosscorrelation has zero during a time of interest. In the LAS-DMA system, the LS code is only used in the spreading of data bits in contrast to the conventional CDMA system. Therefore the LS code pair setting and allocation order should be dealt with carefully considering the special properties of LS code. This paper is intended as an investigation of the setting LS code pair and the sequential allocation method. Firstly, the optimum LS code pair set is proposed in order to minimize PAPR. Secondly, the sequential allocation method is studied to either minimize PAPR or expand IFW.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.154-163
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• 1999

A multiresidue method(MRM) for pesticides must be rapid and must test a wide variety of pesticides at relevant toxicological concentrations. In this study, three kinds of major analytical methods such as Korean Food Code Method, CDFA MRM, and Holstege's method are tested to compare the average recoveries, solvent consumption, and required time for the analysis of 18 organochlorines, 18 organophosphates, and 6 carbamates in spinach samples. Samples for pesticides analysis were extracted and cleaned up according to the respective methods and detected by gas chromatography with selective detectors, ECD and NPD, HPLC with postcolumn reaction system(PCRS). Average recovery of 42 pesticides by Korean Food Code method, CDFA method, and Holstege's method were 91.3%, 88.1%, 89.0%, respectively. Amount of solvent consumption and required time for the analysis of Korean Food Code method were from two and a half times to three times as much as those of another two methods. For the development and legal application of more rapid and effective MRMs, prolonged study is necessary.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.997-1005
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• 2008

In this paper, we proposed advanced T-DMB system which is based on Eureka-147 using UEP coding methods and hiererchical modulation for providing additional services while maintaining BER performance. We simulated the proposed advanced T-DMB system using unequal l6QAM modulation scheme combined with various bit split methods and coding methods such as double binary turbo code of DVB-RCS standard and LDPC code of DVB-S2 standard. In the simulation results, double binary turbo code and LDPC code of proposed advanced T-DMB system have coding gain of 2dB and 3.5dB compared to conventional T-DMB system respectively.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.100-103
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• 2001

The best solution to improve the execution speed of Java program is to make use of the high speed JVM(Java Virtual Machine). The performance of JVM depends on the difference of its implementation. One of the technologies to enhance JVM performance is a JIT(Just-in-Time) code generator. The JIT code generator transforms Java byte code to the native machine code in accordance with computer system platform. The native machine code is faster than the existing interpreter method, since it can reduce the time to analyze the Java byte code. But the JIT code generator have the problem of increasing the traffic between stack and register because of using many register. Therefore, this paper suggests how to reduce the traffic by applying the policy of stack allocation to JIT code generation, as one of the methods to enhance the performance of JVM.

• Convergence Security Journal
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• v.14 no.7
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• pp.9-15
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• 2014

In this paper, we proposed a new LDP code to solve a previous LDP code's problem and can include a face-color information. To include the face-color information, we developed various methods reducing the existing LDP code and analyzed the results. A new LDP code is represented by 6-bits different from the previous LDP code To adapt to a noise and environmental changes effectively and include 2-bits face-color information. The result shows better recognition rates of face and facial-expression than the existing methods effectively.

• Journal of Computing Science and Engineering
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• v.10 no.2
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• pp.39-50
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• 2016

In this paper, we present a comparative study of spatial domain features for writer identification and verification with different ink width conditions. The existing methods give high error rates, when comparing two handwritten images with different pen types. To the best of our knowledge, we are the first to design the feature with different ink width conditions. To address this problem, contour based features were extracted using a chain code method. To improve accuracy at higher levels, we considered histograms of chain code and variance in bins of histogram of chain code as features to discriminate handwriting samples. The system was trained and tested for 1,000 writers with two samples using different writing instruments. The feature performance is tested on our newly created dataset of 4,000 samples. The experimental results show that the histogram of chain code feature is good compared to other methods with false acceptance rate of 11.67%, false rejection rate of 36.70%, average error rates of 24.18%, and average verification accuracy of 75.89% on our new dataset. We also studied the effect of amount of text and dataset size on verification accuracy.