• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.3
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• pp.459-469
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• 2023

The number of IoT devices is explosively increasing due to the development of embedded equipment and computer networks. As a result, cyber threats to IoT are increasing, and currently, malicious codes are being distributed and infected to IoT devices and exploited for DDoS. Currently, IoT devices that are the target of such an attack have various installation environments and have limited resources. In addition, IoT devices have a characteristic that once set up, the owner does not care about management. Because of this, IoT devices are becoming a blind spot for management that is easily infected with malicious codes. Because of these difficulties, the threat of malicious codes always exists in IoT devices, and when they are infected, responses are not properly made. In this paper, we will design an malware detection system for IoT in consideration of the characteristics of the IoT environment and present detection rules suitable for use in the system. Using this system, it will be possible to construct an IoT malware detection system inexpensively and efficiently without changing the structure of IoT devices that are already installed and exposed to cyber threats.

• Tribology and Lubricants
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• v.28 no.4
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• pp.160-166
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• 2012

This paper presents a Reynolds equation solver for hydrostatic gas bearings, implemented to run on graphics processing units (GPUs). The original analysis code for the central processing unit (CPU) was modified for the GPU by using the compute unified device architecture (CUDA). The red-black Gauss-Seidel (RBGS) algorithm was employed instead of the original Gauss-Seidel algorithm for the iterative pressure solver, because the latter has data dependency between neighboring nodes. The implemented GPU program was tested on the nVidia GTX580 system and compared to the original CPU program on the AMD Llano system. In the iterative pressure calculation, the implemented GPU program showed 20-100 times faster performance than the original CPU codes. Comparison of the wall-clock times including all of pre/post processing codes showed that the GPU codes still delivered 4-12 times faster performance than the CPU code for our target problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1626-1634
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• 1993

In this paper we propose a coding scheme which combines source codes and error correcting codes in order to be robus to channel noise. One of the coding schemes that take into account both the source and the channel is the channel optimized quantizer (COQ) which simultaneously minimizes quantization noise and the noise due to channel errors. This paper deals with the problem of combining channel optimized quantizers with ECC to build an improved system. To be specific, we computed the performance of an n bit COQ and that of an n-1 bit COQ followed by an (n-1)/n punctured convolutional code. From this result whether or not the ECC are selected is determined by the number of allocated bits and the channel bit error rate. These results are applied to the image trans-mission method using DCT, and the system performances are evaluated.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.307-312
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• 2005

In this work, we study the performance of a serial concatenated scheme comprising a convolutional code (CC) and an orthogonal space-time block code (STBC) separated by an inter-leaver. Specifically, we derive performance bounds for this concatenated scheme, clearly quantify the impact of using a CC in conjunction with a STBC, and compare that to using a STBC code only. Furthermore, we examine the impact of performing antenna selection at the receiver on the diversity order and coding gain of the system. In performing antenna selection, we adopt a selection criterion that is based on maximizing the instantaneous signal-to­noise ratio (SNR) at the receiver. That is, we select a subset of the available receive antennas that maximizes the received SNR. Two channel models are considered in this study: Fast fading and quasi-static fading. For both cases, our analyses show that substantial coding gains can be achieved, which is confirmed through Monte-Carlo simulations. We demonstrate that the spatial diversity is maintained for all cases, whereas the coding gain deteriorates by no more than $10\;log_{10}$ (M / L) dB, all relative to the full complexity multiple-input multiple-output (MIMO) system.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.190-196
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• 2012

In this paper, we propose an improved error correction code in order to improve the performance of digital modems for HF data communications and verify the performance of the proposed scheme. The proposed scheme employs outer Reed-Solomon codes concatenated with inner convolutional codes. Numerical results show that the proposed system significantly improves the bit error rate performance compared to the conventional PACTOR-III modems. Hence, the proposed system can improve the bandwidth efficiency of digital modems for HF data communications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.83-86
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• 2007

In the blind Maximum-likelihood (ML) detection for Orthogonal Space-Time Block Codes (OSTBC), the problem of ambiguity in determining the symbols has been a great concern. A solution to this problem is to apply semi-blind ML detection, i.e., the blind ML decoding with pilot symbols or training sequence. In order to increase the performance, the number of pilot symbols or length of training sequence should be increased. Unfortunately, this leads to a significant decrease in system spectral efficiency. This work presents an approach to resolve the aforementioned issue by introducing a new method for constructing transmitted information symbol. Thus, by transmitting information symbols drawn from different modulation constellation, the ambiguity can be easily eliminated in blind detection. Also, computer simulations are implemented to verify the performance of the proposed approach.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.1
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• pp.34-41
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• 2010

In this paper, we analyze and simulate co-channel interference (CCI) mitigation method for cooperative communication systems employing decode-and-forward relays. In co-channel interference mitigation method, A source transmits signals that are encoded by orthogonal code. Then, the receiver can distinguish its own signals form the received signals by using the orthogonal code which is already known to the receiver. The orthogonal codes applied to this paper are orthogonal Gold codes. However, we can employ other codes, which have orthogonality, as the orthogonal code. In addition, we utilize a space time block coding (STBC) scheme for enhancing the system performance by obtaining additional array gain.

• Journal of Korea Game Society
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• v.16 no.1
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• pp.119-128
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• 2016

In this paper, we consider an improved deformation method of IFS(iterated function system) fractal using codes of fractal points. In the existing deformation methods, the intermediate results of position dependent partial deformation propagate randomly due to the randomly selected maps of iteration. Therefore, in many cases, the obtained results become somewhat monotonous feeling shapes. To improve these limitations, we propose a method in which the selection of maps are controlled by codes of fractal points. Applying this method, we can obtain interesting fractal deformation conforming with its fractal features. Also, we propose a simple method, incorporating state variables, that can be applied to deformation of some fractal features other than position coordinates.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.1
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• pp.69-73
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• 2018

Korean-peacekeeper's transparent armors in Iraq showed delamination, cracking and clouding a decade ago. And there were also similar deterioration recurrences in KLTV during the operational test a few years ago. Also, the differences between operational capability & lab Bullet-proof test condition, and insufficiency of military protection spec resulted in incomplete bullet-proof results. Moreover, although so many ground weapon systems have been developed, there were not secure test & evaluation codes to verify transparent armoured glasses equal to advanced-overseas products. So in this study, first, environmental test codes were established that all tests should be carried out as the application of only one specimen with newly adopted thermal shock test instead of completing each test with different one. Second, protection standards were integrated through the analysis of global developed country's specifications and reinforced as adding to the real mock-up condition if vehicle's glasses are smaller than standard specimen. Hereby, by applying to test-codes which including actual operational & vehicular conditions, the gap between development test and operational environment was minimized.

• Nuclear Engineering and Technology
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• v.30 no.2
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• pp.112-127
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• 1998

The present study is to assess the applicability of the best-estimate thermal-hydraulic codes, RELAP5/MOD3.2 and CATHARE2V1.3U, to the analysis of thermal-hydraulic behavior in PWRs during midloop operation following the loss of RHRS. The codes simulate an integral test, BETHSY 6.94, which was conducted in the large scale test facility of BETHSY in France. The test represents the accident where the loss of RHRS occurs during midloop operation with the pressurizer and upper head vents open and the sight level indicator broken. Besides, the hot legs are half filled with water and the upper parts of the primary cooling system are filled with nitrogen, with a letdown line open and only one SG available. The purposes of this study are to understand the physical phenomena associated with reflux cooling in the 5G U-tubes when noncondensable gas is present under low pressure and to assess the applicability of the codes to simulate the loss of RHRS event by comparing the predictions with the test results. The results of the study may contribute to actual applications for plant safety evaluation and description of the emergency operating procedure.