• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1105-1120
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• 2015

With the proposed principle of two-dimensional matrix bar code design based on masks, the whole surface of a 2D bar code is used for creating graphic patterns. Masks are a method of overlaying certain information with complete preservation of encoded information. In order to ensure suitable mask performance, it is essential to create a set of masks (mask folder) which are similar to each other. This ultimately allows additional error correction on the whole code level which is proven mathematically through an academic example of a QR code with a matrix of size $9{\times}9$. In order to create a mask folder, this article will investigate parameters based on Weber's law. With the parameters founded in the research, this principle shows how QR codes, or any other 2D bar code, can be designed to display two different messages. This ultimately enables a better description of a 2D bar code, which will improve users' visual recognition of 2D bar code purpose, and therefore users' greater enjoyment and involvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2C
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• pp.168-172
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• 2012

An UHF RFID tag is designed and fabricated using the national code in a bar-code with conductive ink. The bar-code sample was taken from a general bar-code from a general box. The conductivity of the conductive ink was measured, and the measured conductivity was used for the simulation tool to design the printed bar-code shape tag antenna. The tag antenna was fabricated using T-matching to reduce the size of the tag, and the bar-code tag antenna is recognized by both a general bar-code reader and an UHF RFID reader. The input reflection coefficient characteristic, the reading range pattern and the reading rate of the tag antenna are measured.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.959-962
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• 2001

Turbo codes of long block sizes have been known to show very good performance in an AWGN channel and the turbo code has been strongly recommended as error correction code for IMT-2000 in 3GPP(3rd Generation Partnership Project). Recently, turbo codes of short block sizes suitable for real time communication systems have attracted a lot of attention. Thus, in this paper we consider the turbo code of 1/3 code rate and short frame size of 192 bits in ITU-R channel model. We analyzed the performance of W-CDMA systems of 10MHz bandwidths employing RAKE receiver with not only MRC diversity but also turbo code.

• Journal of electromagnetic engineering and science
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• v.7 no.1
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• pp.1-6
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• 2007

Recently, Mc(Multi-code) modulation/demodulation(modem) technique has been explored for high speed data transmission in wireless environment. The conventional Mc modem generates some side effects such as allocating Walsh codes, which motivates to propose a novel Mc modem method with sub-code. Our proposed system should expanded the size of sub-code to provide high-rate data transmission, which also affect adversely to the performance of the system with high PAPR(Peak to Average Power Ratio). Thus, in this paper, we propose a novel pre-coded Multi-Dimensional HCOC(High Capacity Orthogonal Code) Mc modem technique to reduce the high PAPR, which enables the performance improvement. This proposed system can be easily designed by concatenating HCOC Mc modem with the generic Mc modem. The pre-coding technique that is used in this paper is CAC(Constant Amplitude Coding), that helps the system maintain the constant transmission power and reduce the maximum transmission power.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.217-220
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• 2001

Turbo codes of long block sizes have been known to show very good performance in an AWGN channel and the turbo code has been strongly recommended as error correction code for IMT-2000 in 3GPP(3$^{rd}$ Ceneration Partnership Project). Recently, turbo codes of short block sizes suitable for real time communication systems have attracted a lot of attention. Thus in this paper we consider the turbo code of 1/3 code rate and short frame size of 192 bits in ITU-R channel model. We analyzed the performance of W-CDMA systems of 10MHz bandwidths employing RAKE receiver with not only MRC diversity but also turbo code..

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.6
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• pp.450-454
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• 2015

Short execution time is the major performance factor for computer systems. This performance factor is directly determined by code quality, which is influenced by the compiler's optimizations. However, a compiler has limitations when optimizing source code due to insufficient information. Thus, if programmers can learn the reasons why a compiler fails to apply optimizations, they can rewrite code that is more easily understood by the compiler, and thus improve performance. In this paper, we propose a compiler that provides a programmer with reasons for failed optimization and recognizes programmer's additional information to obtain better optimization. As a result, we obtain performance improvement, i.e., reducing execution time and code size, by taking advantage of additional optimization opportunities.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.42-45
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• 2012

A network processor (NP) is an application-specific instruction-set processor for fast and efficient packet processing. There are many issues in compiler's code generation and optimization due to NP's hardware constraints and special hardware support. In this paper, we describe in detail how to resolve the issues. Our compiler was developed on LLVM 3.0 and the NP target was our in-house network processor which consists of 32 64-bit RISC processors and supports multi-context with special hardware structures. Our compiler incurs only 9.36% code size overhead over hand-written code while satisfying QoS, and the generated code was tested on a real packet processing hardware, called S20 for code verification and performance evaluation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.113-118
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• 2011

This paper has analyzed recognizing performance depending on the size of iris codes extracting by iris recognition algorithm using scale-space filtering. The iris images were created through pre-processing, the features were extracted by scale-space filtering, and the codes of 16 sizes were generated. The generated code's performance was compared for each code to calculate FAR and FRR by matching method utilizing Hamming distance. Every code had little overlapping portion between same person and other persons group so that the proposed algorithm's superiority was proved, and the performance of iris codes was analyzed for each size focused on convenience to use when implementing in realization. In addition, the iris codes suitable to iris recognition system that is high-reliable and is able to reduce user's inconvenience due to mis-rejection has been presented considering for commercialization.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.3
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• pp.159-167
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• 2017

Software safety is a key issue in embedded system of automotive and aviation industries. Various software testing approaches have been proposed to achieve software safety like ISO26262 Part 6 in automotive environment. In spite of one of the classic and basic approaches, stack memory is hard to estimating exactly because of uncertainty of target code generated by compiler and complex nested interrupt. In this paper, we propose an approach of analyzing the maximum stack usage statically from target binary code rather than the source code that also allows nested interrupts for determining the exact stack memory size. In our approach, determining maximum stack usage is divided into three steps: data extraction from ELF file, construction of call graph, and consideration of nested interrupt configurations for determining required stack size from the ISR (Interrupt Service Routine). Experimental results of the estimation of the maximum stack usage shows proposed approach is helpful for optimizing stack memory size and checking the stability of the program in the embedded system that especially supports nested interrupts.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.215-218
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• 1998

This paper proposes a blind multi-user detector using Code-Constrained Minimum Variance (CCMV) method which directly detects the DS-CDMA signals in a multipath fading channel without estimating the channels. This algorithm reduces the complexity of computation by making a small size data matrix with the order of the channel length. Advantageously it requires to know the spreading code and the time delay of only the desired user.