• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.13-20
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• 2019

For customized education, it is essential to search the learning path for the learner. The genetic algorithm makes it possible to find optimal solutions within a practical time when they are difficult to be obtained with deterministic approaches because of the problem's very large search space. In this research, based on genetic algorithm, the learning paths to learn 200 chords in 27 music sheets were optimized to maximize the learning effect by balancing and minimizing learner's burden and learning size for each step in the learning paths. Although the permutation size of the possible learning path for 27 learning contents is more than $10^{28}$, the optimal solution could be obtained within 20 minutes in average by an implemented tool in this research. Experimental results showed that genetic algorithm can be effectively used to design complex learning path for customized education with various purposes. The proposed method is expected to be applied in other educational domains as well.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.3
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• pp.533-543
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• 2018

In this paper, we propose an MILP-based method for Optimal Probability of Bit-based Differential Characteristic in SP(Substitution-permutation) ciphers based on Automatic Differential Characteristic Searching Method of Sasaki, et al. In [13], they used input/output variables and probability variables seperatably, but we simplify searching procedure by putting them(variables) together into linear inequalities. Also, In order to decrease the more linear inequalities, we choose Espresso algorithm among that used by Sasaki, et al(Quine-McCluskey algorithm & Espresso algorithm). Moreover, we apply our method to GIFT-64, GIFT-128, SKINNY-64, and we obtained results in the GIFT(Active S-boxs : 6, Probabilities : $2^{-11.415}$) compared with the existing one.(Active S-boxs : 5, Probabilities : unknown). In case of SKINNY-64, we can't find better result, but can find same result compared with the existing one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.1-7
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• 2018

The IoT environment provides an infinite variety of services using many different devices and networks. The development of the IoT environment is directly proportional to the level of security that can be provided. In some ways, lightweight cryptography is suitable for IoT environments, because it provides security, higher throughput, low power consumption and compactness. However, it has the limitation that it must form a new cryptosystem and be used within a limited resource range. Therefore, it is not the best solution for the IoT environment that requires diversification. Therefore, in order to overcome these disadvantages, this paper proposes a method suitable for the IoT environment, while using the existing block cipher algorithm, viz. the lightweight cipher algorithm, and keeping the existing system (viz. the sensing part and the server) almost unchanged. The proposed BCL architecture can perform encryption for various sensor devices in existing wire/wireless USNs (using) lightweight encryption. The proposed BCL architecture includes a pre/post-processing part in the existing block cipher algorithm, which allows various scattered devices to operate in a daisy chain network environment. This characteristic is optimal for the information security of distributed sensor systems and does not affect the neighboring network environment, even if hacking and cracking occur. Therefore, the BCL architecture proposed in the IoT environment can provide an optimal solution for the diversified IoT environment, because the existing block cryptographic algorithm, viz. the lightweight cryptographic algorithm, can be used.

• Journal of Food Hygiene and Safety
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• v.19 no.4
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• pp.176-184
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• 2004

This study was conducted to compare and estimate the daily PAHs dietary intake from both home-cooking and dining-out, through approach of model diet used in exposure assessment of food contaminants. Food commodities reflecting in model diet were selected from the KHIDI report and were analysed in cooked or uncooked edible forms using HPLC-Fluorscence Detector. The PAHs dietary intake comparison between home-cooking and dining-out was based on one meal intake suggested in model diet and PAHs dietary intake was estimated by using food consumption rate and body weight of the Korean adult group. The daily PAHs dietary intake was calculated by permutation and combination method with assumption that a person consumed 2 meals from home-cooking menu and 1 meal from dining-out menu. The total PAHs levels in 36 food commodities with 200 samples were ranged from 2.00 ug/kg to 141.28 ug/kg and a food showing the highest PAHs level was the stir-fried anchovy. The $TEQ_{BaP}$ levels of PAHs were calculated using benzo(a)pyrene equivalents individual congener level and corresponding TEF value and the $TEQ_{BaP}$ level were ranged from $0.03\;ugTEQ{BaP}$ to $1.31\;ugTEQ_{BaP}$ and a food showing the highest $TEQ_{BaP}$ level was the hamburger. The PAHs dietary intakes per one meal from home-cooking and dining-out were $2.4\times10^{-3}\;ugTEQ_{BaP}/kg/meal\;and\;4.0\times10^{-3}\;ugTEQ_{BaP}/kg/meal$, respectively. This data showed the PAHs dietary intake from dining-out was about 1.7 times higher than from the home-cooking. The daily PAHs dietary intakes of general Korean adult having two meals from home-cooking and one meal from dining-out per a day were ranged between $8.0\times10^{-3}\~9.7\times10^{-3}\;ugTEQ_{BaP}/gg/day$ and mean value as $8.9\times10^{-3}\~9.7\times10^{-3}\;ugTEQ_{BaP}/gg/day$.