• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.783-796
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• 2014

The coarse mesh finite difference (CMFD) method is applied to the discontinuous finite element method based discrete ordinate calculation for source convergence acceleration. The three-dimensional (3-D) DFEM-Sn code FEDONA is developed for general geometry applications as a framework for the CMFD implementation. Detailed methods for applying the CMFD acceleration are established, such as the method to acquire the coarse mesh flux and current by combining unstructured tetrahedron elements to rectangular coarse mesh geometry, and the alternating calculation method to exchange the updated flux information between the CMFD and DFEM-Sn. The partial current based CMFD (p-CMFD) is also implemented for comparison of the acceleration performance. The modified p-CMFD method is proposed to correct the weakness of the original p-CMFD formulation. The performance of CMFD acceleration is examined first for simple two-dimensional multigroup problems to investigate the effect of the problem and coarse mesh sizes. It is shown that smaller coarse meshes are more effective in the CMFD acceleration and the modified p-CMFD has similar effectiveness as the standard CMFD. The effectiveness of CMFD acceleration is then assessed for three-dimensional benchmark problems such as the IAEA (International Atomic Energy Agency) and C5G7MOX problems. It is demonstrated that a sufficiently converged solution is obtained within 7 outer iterations which would require 175 iterations with the normal DFEM-Sn calculations for the IAEA problem. It is claimed that the CMFD accelerated DFEM-Sn method can be effectively used in the practical eigenvalue calculations involving general geometries.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.229-237
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• 2013

As demand for IT services increase, which are based on SOA and cloud computing, service level agreements (SLAs) have received more attention in the parties concerned. An SLA is usually a paper contract written in natural language. SLA management tools which are commercially available, implement SLAs implicitly in the application with a procedural language. This makes automation of SLA management difficult. It is also laborious to maintain contract management systems because changes in a contract give rise to extensive modifications in the source code. We see the source of the trouble is the existence of documentary SLAs (paper contracts) and corresponding executable SLAs (contracts coded in the procedural language). In this paper, to resolve the current SLA management problems we propose an active SLM (Active Service Level Management) system, which is based on the active SLA (Active Service Level Agreement). In the proposed system, the separated management and processing of dual SLAs can be unified into a single process with the introduction of active SLAs (ASLAs).

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.2
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• pp.95-103
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• 2011

This paper proposes a 6b 1.2 GS/s 47.8 mW 0.17 $mm^2$ 65 nm CMOS ADC for high-rate wireless personal area network systems. The proposed ADC employs a source follower-free flash architecture with a wide input range of 1.0 $V_{p-p}$ at a 1.2 V supply voltage to minimize power consumption and high comparator offset effects in a nanometer CMOS technology. The track-and-hold circuits without source followers, the differential difference amplifiers with active loads in pre-amps, and the output averaging layout scheme properly handle a wide-range input signal with low distortion. The interpolation scheme halves the required number of pre-amps while three-stage cascaded latches implement a skew-free GS/s operation. The two-step bubble correction logic removes a maximum of three consecutive bubble code errors. The prototype ADC in a 65 nm CMOS demonstrates a measured DNL and INL within 0.77 LSB and 0.98 LSB, respectively. The ADC shows a maximum SNDR of 33.2 dB and a maximum SFDR of 44.7 dB at 1.2 GS/s. The ADC with an active die area of 0.17 $mm^2$ consumes 47.8 mW at 1.2 V and 1.2 GS/s.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.1011-1015
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• 2013

This paper analyses the violation rate of CJK joint Chines character Unicode to the source code rule. In the paper, Chinese character 150ea in Chinese Unicode which have relatively a higher frequency in use of a character was chosen to study. The frequency rate in use of the 150ea characters is about 50% of the total frequency rate of the Chinese characters. The study was applied the AMI/HDB-3 line coding/scrambling and HDLC protocol, According to the analyses, the number of violated characters were 77ea of 150 ea, frequency rate in use 29%. Therefore, when the violated 77ea characters are replaced to the matched character codes to the source coding rule, the processing rate of the line coder can be improved about 37%.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.99-106
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• 2008

Recently developed compilers perform some optimizations in order to speed up the execution time of source program. These optimizations require the reordering of the sequence of program statements. This reordering does not give any problems in a single-threaded program. However, the reordering gives some significant errors in a multi-threaded program. State-of-the-art model checkers such as JavaPathfinder do not consider the reordering resulted in the optimization step in a compiler since they just consider a single memory model. In this paper, we develop a new verification tool to verify Java source program based on Java Memory Model. And our tool is capable of handling the reordering in verifying Java programs. As a result, our tool finds an error in the test program which is not revealed with the traditional model checker JavaPathFinder.

• The Transactions of the Korea Information Processing Society
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• v.5 no.3
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• pp.633-648
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• 1998

Rapid computing environment, change of the application structure, and various user demand will increase the demand of the software development. Version control is helpful to improve productivity using delta, and useful to establish component from existing data of source code. This paper presents the design and implementation of the version control system. which is composed of retrieval system and delta management system. In retrieval system, vanous retrieve methods arc proposed. This methods provides the process methodology with filename, content, size and date. Various retrieve methods arc important for the effective delta management. Meta data can be easily composed for the delta management by these methods. Compared with other systems, this implemented version control system has some advantage. First, for delta management, version maintenance for delta management becomes easier by integrating the forward and back-ward methods. Second, delta managent part of a project is to unite the forward and backward method. the effieiency of this system is to increased in management. Also, this system supports a thechnique of using the database and files for project repository and makes the version management more effective.

• Journal of KIISE
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• v.42 no.9
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• pp.1100-1108
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• 2015

Classes.dex, which is the executable file for android operation system, has Java bite code format, so that anyone can analyze and modify its source codes by using reverse engineering. Due to this characteristic, many android applications using classes.dex as executable file have been illegally copied and distributed, causing damage to the developers and software industry. To tackle such ill-intended behavior, this paper proposes a technique to encrypt classes.dex file using an AES(Advanced Encryption Standard) encryption algorithm and decrypts the applications encrypted in such a manner in order to prevent reverse engineering of the applications. To reinforce the file against reverse engineering attack, hash values that are obtained from substituting a hash equation through the combination of salt values, are used for the keys for encrypting and decrypting classes.dex. The experiments demonstrated that the proposed technique is effective in preventing the illegal duplication of classes.dex-based android applications and reverse engineering attack. As a result, the proposed technique can protect the source of an application and also prevent the spreading of malicious codes due to repackaging attack.

• Journal of Advanced Navigation Technology
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• v.19 no.2
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• pp.153-160
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• 2015

This paper has studied about the scrambling occurrence frequency in UTF-8 coding system for Unicode Hangul Jamo codes. The scrambling methode applied in the study is HDB-3 in AMI line coding that is international transmission standard. In the study, the source coding rule was applied to analysis the scrambling occurrence. The quantity of the scrambling occurrence was calculated by the number of times and frequency rate of the scrambling occurrence in Hangul Jamo and Compatibity Hangul Jamo. In the case of Hangul Jamo, the number of times and frequency rate in Unicode and UTF-8 were 24times, 52% and 148times, 228% respectively. In the case of Compatibility Hangul Jamo, that were 10times, 14% and 83times, 131% respectively. As a result, when Hangul Jamo and Compatibility Hangul Jamo in UNICODE were transformed to UTF-8, the scrambling frequency rates were increased 340% and 851% respectively.

• Journal of Radiation Industry
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• v.11 no.3
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• pp.157-165
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• 2017

In this paper, we calculate the light photons collection efficiency of large-volume plastic scintillation detector mainly used for radiation portal monitor (RPM). A Monte Carlo light photon transport code, DETECT2000, were used to quantitatively evaluate light collection efficiency of plastic scintillation detector. DETECT2000 calculated the placement of light collection efficiency based on the energy spectrum. We calculated the light collection efficiency relative to the position of the energy spectrum that proportional to the placement of the source. The $850{\times}285{\times}65mm^3$ size of polyvinyl toluene (PVT) scintillator was used for measurements. Through DETECT2000 simulation, the light collection efficiency of $5{\times}5$ arrays were calculated and verification was performed by comparing with experimentally measured. And then, the corrected MCNP simulation by applying the light collection efficiency in $21{\times}13$ arrays was compared and analyzed. Comparing the Monte Carlo simulation with measured results, it shows an average difference of 10.1% in $5{\times}5$ arrays. Particularly, about twice of the difference was found in the edge of first column, which coupled with PMT. In whole $5{\times}5$ array, the overall ratio was the same except for the first column. And then comparing the energy spectra of the $21{\times}13$ array with and without the light collection efficiency, it shows a difference of 6.69% in Compton edge area. The DETECT2000 based light collection efficiency simulation showed well agreement with the point source experiment. And comparing with measured energy spectra, we could compare the differences according to whether or not the light collection efficiency was applied. As a results, it is possible to increase the accuracy and reliability of Monte Carlo simulation results by pre-calculating the light collection efficiency according to the PVT geometry by using the DETECT2000.

• Progress in Medical Physics
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• v.29 no.4
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• pp.101-105
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• 2018

In this paper, a neutron moderation system for boron neutron capture therapy (BNCT) based on a $^{252}Cf$ neutron source is proposed. Different materials have been studied in order to produce a high percentage of epithermal neutrons. A moderator with a construction mixture of $AlF_3$ and Al, three reflectors of $Al_2O_3$, BeO, graphite, and seven filters (Bi, Cu, Fe, Pb, Ti, a two-layer filter of Ti+Bi, and a two-layer filter of Ti+Pb) is considered. The MCNPX simulation code has been used to calculate the neutron and gamma flux at the output window of the neutronic system. The results show that the epithermal neutron flux is relatively high for four filters: Ti+Pb, Ti+Bi, Bi, and Ti. However, a layer of Ti cannot reduce the contribution of ${\gamma}$-rays at the output window. Although the neutron spectra filtered by the Ti+Bi and Ti+Pb overlap, a large fraction of neutrons (74.95%) has epithermal energy when the Ti+Pb is used as a filter. However, the percentages of the fast and thermal neutrons are 25% and 0.5%, respectively. The Bi layer provides a relatively low epithermal neutron flux. Moreover, an assembly configuration of 30% $AlF_3+70%$ Al moderator/$Al_2O_3$ reflector/a two-layer filter of Ti+Pb reduces the fast neutron flux at the output port much more than other assembly combinations. In comparison with a recent model suggested by Ghassoun et al., the proposed neutron moderation system provides a higher epithermal flux with a relatively low contamination of gamma rays.