• ETRI Journal
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• v.38 no.2
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• pp.387-396
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• 2016

This paper introduces a new type of collision attack on first-order masked Advanced Encryption Standards. This attack is a known-plaintext attack, while the existing collision attacks are chosen-plaintext attacks. In addition, our method requires significantly fewer power measurements than any second-order differential power analysis or existing collision attacks.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.256-257
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• 2013

이 논문에서는 셔플링 컨버터를 이용해 다중 태양광 모듈의 최대 전력점 추종시 각 태양광 모듈간의 전류 편차에 의해 셔플링 컨버터에 과전류가 흐르는 것을 방지하기 위해 태양광 모듈에서의 전류 편차를 이용해 셔플링 컨버터에서의 전류를 계산하는 법을 고안하고, 이를 이용해 전류를 제한하는 기법을 제안하였다. 제안하는 방식을 증명하기 위해 PSIM 소프트웨어를 이용하여 그 타당성을 입증하였다.

• KSBB Journal
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• v.16 no.2
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• pp.107-114
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• 2001

The dynamic evolution process has resulted in the myriad shapes, functions, and systems evident in every living organism. For centuries, people have been harnessing the power of evolution to produce new varieties of plants and animals, such as producing tomatoes from berries and Chihuahuas from wolves. Now scientists are using it to produce better molecules, ranging from drugs to industrial chemicals, and doing it in days or weeks rather than eons. The ingenious process, which creates genetic diversity and selects those with desired features in the laboratory, is called directed evolution or test tube evolution. In this paper, concepts of directed molecular evolution and some examples will be discussed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.222-222
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• 2004

• Journal of Computing Science and Engineering
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• v.8 no.4
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• pp.187-198
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• 2014

In this paper an efficient image encryption scheme based on cyclic rotations and multiple blockwise diffusions with two chaotic maps is proposed. A Sin map is used to generate round keys for the encryption/decryption process. A Pomeau-Manneville map is used to generate chaotic values for permutation, pixel value rotation and diffusion operations. The encryption scheme is composed of three stages: permutation, pixel value rotation and diffusion. The permutation stage performs four operations on the image: row shuffling, column shuffling, cyclic rotation of all the rows and cyclic rotation of all the columns. This stage reduces the correlation significantly among neighboring pixels. The second stage performs circular rotation of pixel values twice by scanning the image horizontally and vertically. The amount of rotation is based on $M{\times}N$ chaotic values. The last stage performs the diffusion four times by scanning the image in four different ways: block of $8{\times}8$ pixels, block of $16{\times}16$ pixels, principal diagonally, and secondary diagonally. Each of the above four diffusions performs the diffusion in two directions (forwards and backwards) with two previously diffused pixels and two chaotic values. This stage makes the scheme resistant to differential attacks. The security and performance of the proposed method is analyzed systematically by using the key space, entropy, statistical, differential and performance analysis. The experimental results confirm that the proposed method is computationally efficient with high security.

• BMB Reports
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• v.43 no.8
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• pp.567-572
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• 2010

In this study, we cloned the ERF-B3 subfamily transcription factor gene BnaERF-B3-hy15 from Brassica napus L. Huyou15. This 600 bp gene encodes a 199 amino acid classic ethylene responsive factor (ERF), which shown no binding or very weak binding GCC box-binding activity by the yeast one-hybrid assay. We used gene shuffling and the yeast one-hybrid system to obtain three mutated sequences that can bind to the GCC box. Sequence analysis indicated that two residues, Gly156 in the AP2 domain and Phe62 at the N-terminal domain were mutated to arginine and serine, respectively. Changes of Gly156 to arginine and Phe62 to serine increased the GCC-binding activity of BnaERF-B3-hy15 and the alter of Gly156 to arginine changed the AP2-domain structure of BnaERF-B3-hy15.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.764-769
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• 2000

The lipase gene(lip) from Bacillus stearothermophilus was recombined in vitro by utilizing the DNA shuffling technique. After four rounds of shuffling, transformation, and screening based on the initial rate of clear zone formation on a tricaprylin plate, a clone (M10) was isolated, the cell extract of which showed about 2.8-fold increased lipase activity. The DNA sequence of the mutant lipase gene (m10) showed 3 base changes, resulting in two cryptic mutations and one amino acid substitution: S113($AGC{\rightarrow}AGT$), L252 ($TTG{\rightarrow}TTA$), and G275E ($GGA{\rightarrow}GAA$). SDS-PAGE analysis revealed that the increased enzyme activity observed in M10 was partly caused by high expression of the m10 lipase gene. The amount of the expressed G275E lipase was estimated to comprise as much as 41% of the total soluble proteins of the cell. The maximum velocity ($V_{max}$) of the purified mutant enzyme for the hydrolysis of olive oil was measured to be 3,200 U/mg, which was 10% higher than that of the parental (WT) lipase (2,900 U/mg). Its optimum temperature for the hydrolysis of olive oil was $68^{\circ}C$ and it showed a typical $Ca^{2+}$-dependent thermostability, properties fo which were the same as those of the WT lipase. However, the mutant enzyme exhibited a high enantiospecificity towards (S)-naproxen compared with the WT lipase. In addition, it showed increased hydrolytic activity towards triolein, tricaprin, tricaprylin, and tricaproin.

• Journal of KIISE
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• v.44 no.4
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• pp.383-391
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• 2017

As we enter a new era of Big Data, the amount of semantic data has rapidly increased. In order to derive meaningful information from this large semantic data, studies that utilize the SWRL(Semantic Web Rule Language) are being actively conducted. SWRL rules are based on data extracted from a user's empirical knowledge. However, conventional reasoning systems developed on single machines cannot process large scale data. Similarly, multi-node based reasoning systems have performance degradation problems due to network shuffling. Therefore, this paper overcomes the limitations of existing systems and proposes more efficient distributed inference methods. It also introduces data partitioning strategies to minimize network shuffling. In addition, it describes a method for optimizing the incremental reasoning process through data selection and determining the rule order. In order to evaluate the proposed methods, the experiments were conducted using WiseKB consisting of 200 million triples with 83 user defined rules and the overall reasoning task was completed in 32.7 minutes. Also, the experiment results using LUBM bench datasets showed that our approach could perform reasoning twice as fast as MapReduce based reasoning systems.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.1
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• pp.11-16
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• 2020

3D printing is one of the emerging technologies and getting a lot of attention. To do 3D printing, 3D model is first generated, and then converted to G-code which is 3D printer's operations. Facet, which is a small triangle, represents a small surface of 3D model. Depending on the height or precision of the 3D model, the number of facets becomes very large and so the conversion time from 3D model to G-code takes longer. Apach Hadoop is a software framework to support distributed processing for large data set and its application range gets widening. In this paper, Hadoop is used to do the conversion works time-efficient way. 2-phase distributed algorithm is developed first. In the algorithm, all facets are sorted according to its lowest Z-value, divided into N parts, and converted on several nodes independently. The algorithm is implemented in four steps; preprocessing - Map - Shuffling - Reduce of Hadoop. Finally, to show the performance evaluation, Hadoop systems are set up and converts testing 3D model while changing the height or precision.

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.51-59
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• 2019

Due to the exponential growth of access information on the web, the need for predicting web users' next access has increased. Various models such as markov models, deep neural networks, support vector machines, and fuzzy inference models were proposed to handle web access prediction. For deep learning based on neural network models, training time on large-scale web usage data is very huge. To address this problem, deep neural network models are trained on cluster of computers in parallel. In this paper, we investigated impact of several important spark parameters related to data partitions, shuffling, compression, and locality (basic spark parameters) for training Multi-Layer Perceptron model on Spark standalone cluster. Then based on the investigation, we tuned basic spark parameters for training Multi-Layer Perceptron model and used it for tuning Spark when training Multi-Layer Perceptron model for web access prediction. Through experiments, we showed the accuracy of web access prediction based on our proposed web access prediction model. In addition, we also showed performance improvement in training time based on our spark basic parameters tuning for training Multi-Layer Perceptron model over default spark parameters configuration.