• Journal of the Korea Society for Simulation
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• v.17 no.1
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• pp.17-22
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• 2008

Double-binary turbo code has been adopted as an error control code of various future communication systems including wireless metropolitan area networks(WMAN) due to its powerful error correction capability. One of the components affecting the performance of turbo code is internal interleaver. In 802.16 d/e system, an almost regular permutation(ARP) interleaver has been included as a part of specification, however it seems that the interleaver is not optimized in terms of decoding performance. In this paper, we propose three optimization methods for the interleaver based on spatial distance, spread and minimum distance between original and interleaved sequence. We find optimized interleaving parameters for each optimization method and evaluate the performances of the proposed methods by computer simulation under additive white Gaussian noise(AWGN) channel. Optimized parameters can provide up to 1.0 dB power gain over the conventional method and furthermore the obtainable gain does not require any additional hardware complexity.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.76-84
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• 2000

Communication systems, including cell-based mobile communication systems, multiple satellite communication systems of multi-beam satellite systems, require reliable handoff methods between cell-to-cell, satellite-to-satellite of beam-to-team, respectively. Recent measurement of a CDMA cellular system indicates that the system is in handoff at about 35% to 70% of an average call period. Therefore, system reliability during handoff is one of the major system performance parameters and eventually becomes a factor in the overall system capacity. This paper presents novel and improved techniques for handoff in cellular communications, multi-beam and multi-satellite systems that require handoff during a session. this new handoff system combines the soft handoff mechanism currently implemented in the IS-95 CDMA with code and packet diversity combining techniques and an iterative decoding algorithm (Turbo Coding). the Turbo code introduced by Berrou et all. has been demonstrated its remarkable performance achieving the near Shannon channel capacity [1]. Recently. Turbo codes have been adapted as the coding scheme for the data transmission of the third generation international cellular communication standards : UTRA and CDMA 2000. Our proposed encoder and decoder schemes modified from the original Turbo code is suitable for the code and packet diversity combining techniques. this proposed system provides not only an unprecedented coding gain from the Turbo code and it iterative decoding, but also gain induced by the code and packet diversity combining technique which is similar to the hybrid Type II ARQ. We demonstrate performance improvements in AWGN channel and Rayleigh fading channel with perfect channel state information (CSI) through simulations for at low signal to noise ratio and analysis using exact upper bounding techniques for medium to high signal to noise ratio.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.3
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• pp.115-124
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• 2005

When the application code is downloaded into the mobile device, it is important to provide authentication. Usually, mobile code execution is overlapped with downloading to reduce transfer delay. To the best of our knowledge, there has not been any algorithm to authenticate the mobile code in this environment. In this paper, we present two efficient code authentication schemes that permit overlapping of execution and downloading under the two cases: the first is when the order of transmission of code chunks is determined before the transmission and the second is when this order is determined during the transmission. The proposed methods are based on hash chaining and authentication trees, respectively. Especially, the latter scheme utilizes previously received authentication informations to verify the currently received chunk, which reduces both communication overhead and verification delay. When the application code consists of n chunks, communication overheads of the both schemes are 0(n) and verification delays of these two schemes are O(1) and O(log n), respectively.

• Journal of Information Processing Systems
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• v.16 no.4
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• pp.915-934
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• 2020

Software refactoring is a process to restructure an existing software code while keeping its external behavior the same. Currently, various refactoring techniques are being used to develop more readable and less complex codes by improving the non-functional attributes of software. Refactoring can further improve code maintainability by applying various techniques to the source code, which in turn preserves the behavior of code. Refactoring facilitates bug removal and extends the capabilities of the program. In this paper, an exhaustive review is conducted regarding bad smells present in source code, applications of specific refactoring methods to remove that bad smell and its effect on software quality. A total of 68 studies belonging to 32 journals, 31 conferences, and 5 other sources that were published between the years 2001 and 2019 were shortlisted. The studies were analyzed based on of bad smells identified, refactoring techniques used, and their effects on software metrics. We found that "long method", "feature envy", and "data class" bad smells were identified or corrected in the majority of studies. "Feature envy" smell was detected in 36.66% of the total shortlisted studies. Extract class refactoring approach was used in 38.77% of the total studies, followed by the move method and extract method techniques that were used in 34.69% and 30.61% of the total studies, respectively. The effects of refactoring on complexity and coupling metrics of software were also analyzed in the majority of studies, i.e., 29 studies each. Interestingly, the majority of selected studies (41%) used large open source datasets written in Java language instead of proprietary software. At the end, this study provides future guidelines for conducting research in the field of code refactoring.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.5
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• pp.189-194
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• 2009

Most of anti-virus programs detect and compare the signature of the malicious code to detect buffer overflow malicious code. Therefore most of anti-virus programs can't detect new or unknown malicious code. This paper introduces a new way to detect malicious code traces memory executable of essentials APIs by malicious code. To prove the usefulness of the technology, 7 sample codes were chosen for compared with other methods of 8 anti-virus programs. Through the simulation, It turns out that other anti-virus programs could detect only a limited portion of the code, because they were implemented just for detecting not heap areas but stack areas. But in other hand, I was able to confirm that the proposed technology is capable to detect the malicious code.

• Journal of The Korean Association of Information Education
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• v.20 no.3
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• pp.293-302
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• 2016

It is the latest fashion of interesting with software education in public school environment and also consider as high priority issue of curriculum for college freshman with programming 101 courses. The block-based programming tool is used widely for the beginner and provides several positive features compare than text-based programming language tools. To measure quality of programming code elaborately which is based script language, it is need to very tough manual process. As a result the previously research related with evaluation of block-based script code has been focused very simple methods in which normalize the number of blocks used which is related with programming concept. In such cases in this, it is difficult to measure structural vulnerability of script code and implicit programming concept which does not expose. In this research, the framework is proposed which enable to measure and evaluate quality of code script of block-based programming tools and also provides method to find of vulnerability of script code. In this framework, the quality metrics is constructed to structuralize implicit programming concept and then developed the quality measure and vulnerability model of script to improve level of programming. Consequently, the proposed methods enable to check of level of programming and predict the heuristic target level.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.842-845
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• 2007

The field of automatic identification using RF is the one of the emerging ubiquitous computing areas. Early RFID techniques was focused on hardware areas, but RFID middleware has recently gained a lot of attention, which collects and filters tag data, and provides it to enterprise applications. The RFID middleware proposed by EPCglobal only can process EPC tag data, and cannot handle the KKR code which is defined by korean organization. So in this paper, we propose a method which can process the KKR code in RFID middleware systems. Using our approach, the RFID middleware can be extended as general ubiquitous middleware systems which process not only EPC code but also KKR code.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.99-104
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• 2012

Watermarking is one of the methods that insist on a copyright as it append digital signals in digital informations like still image, video, ets. This paper proposed a novel digital watermarking scheme which combines a QR code and a watermarking method using DCT coefficient. It proposed an algorithm for selecting a QR code from a image and to be converted into a watermark. It processed a watermarking process using expanded watermarking method in DCT area. This simulation results showed that the PSNR difference between the proposed scheme and the original image was 33.98dB and the normalized correlation between the proposed scheme and the original image was above 99.51. The proposed method is reusable.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.1-9
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• 2012

PURPOSES: A viscoelastic axisymmetric finite element analysis code has been developed for stress analysis of asphalt pavement structures. METHODS: Generalized Maxwell Model (GMM) and 4-node isoparametric element were employed for finite element formulation. The code was developed using $C^{+}^{+}$ computer program language and named as KICTPAVE. For the verification of the developed code, a structural model of a pavement system was constructed. The structural model was composed of three layers: asphalt layer, crushed stone layer, and soil subgrade. Two types of analysis were considered for the verification: (1)elastic static analysis, (2)viscoelastic time-dependent analysis. For the elastic static analysis, linear elastic material model was assigned to all the layers, and a static load was applied to the structural model. For the viscoelastic time-dependent analysis, GMM and linear elastic material model were assigned to the asphalt layer and all the other layers respectively, and a cyclic loading condition was applied to the structural model. RESULTS: The stresses and deformations from KICTPAVE were compared with those from ABAQUS. The analysis results obtained from the two codes showed good agreement in time-dependent response of the element under the loading area as well as the surface deformation of asphalt layer, and horizontal and vertical stresses along the axisymmetric axis. CONCLUSIONS: The validity of KICTPAVE was confirmed by showing the agreement of the analysis results from the two codes.

• Fashion & Textile Research Journal
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• v.6 no.6
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• pp.785-798
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• 2004

Silk has always been coveted as the finest and richest of all fibers woven into cloth. The earlist woven silk fragments found to date come from the third century B.C. The filament created and spun into cocoon by the larva of the silk moth, silk was exported from China to Europe from as early as the third century B.C. Silk industry is export leading industry that guide national textile industry development after the 1960s in Korea. Korean silk industry reached to peak at 1975 is displaying appearance that export scale is decreased recently. Various kinds methods can be proposed for high value added in silk industry, the research about color is essential. The importance of color is increasing in modern textile and fashion industry. Color is important factor of textile and fashion industry because color affects strong influence in human's sensitivity. Silk fabric can give high added value developing high sensitivity color because dye ability is superior. In this study I planned the "Utility Silk Color Code 288" for efficient color management in silk industry. "Utility Silk Color Code 288" are attached the Munsell notation and dyeing data which can reappear the color when needed. This research constructs for insufficient domestic color infrastruction and expect that basic role to develop the competitive power for Korean silk industry.