• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.4
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• pp.569-575
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• 2024

The 64-bit block cipher IIoTBC is an encryption algorithm designed for the security of industrial IoT devices and uses an 128-bit secret key. The IIoTBC's encryption algorithm varies depending on whether the MCU size used in IoT is 8-bit or 16-bit. This paper deals with a differential attack on IIoTBC when the MCU size is 8-bit. It attacks 15-round out of the entire 32-round using IIoTBC's 14-round differential characteristic. At this time, the number of required plaintexts and encryption are 2⁵⁷ and 2^122.4, respectively. The differential characteristic presented in this paper has a longer round than the existing 13-round impossible differential characteristic, and the attack using this is the result of the first key recovery attack on IIoTBC.

• Communications of the Korean Mathematical Society
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• v.20 no.3
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• pp.411-426
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• 2005

본 논문에서는 상미분방정식, 지연미분방정식, 중립형 지연미분방정식, 그리고 차분방정식 의 안정성에 관한 연구방법과 최근의 연구동향들을 간략하게 소개하였다.

• Communications of the Korean Mathematical Society
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• v.20 no.4
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• pp.623-640
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• 2005

본 논문에서는 양정수n의 q-유사를 이용한 q-이항정리, q-차례곱, q-차분 연산자, q-적분에 관한 최근의 기본개념을 정리하고, 이를 적용하여 q-베타함수와 q-감마함수의 새로운 q-유사에 대한 특징을 간략하게 논한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.228-237
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• 2013

In this paper, we propose a normalized cross correlation(NCC)-based multiview background subtraction method which is robust when an object and background have similar color. When the background of the capturing environment is not artificially composed, the regions in the background images which would be occluded by an object tends to have difference colors. The colors of those regions, however, becomes similar when an object enters the capturing environment. Based on this assumption, this paper proposes a concept of GoNCC(Graph of Normalized Cross Correlation). GoNCC is the distribution of NCC between a pixel in an image and pixels related by epipolar constraints with the pixel. The proposed multiview background subtraction method is performed by comparing GoNCC of the current images with the background images. To reduce computational complexity, we perform multiview background subtraction only to the pixels undetermined by single view background subtraction. Experimental results show that the proposed method is more robust to color similarity between an object and background than a single-view background subtraction method and a previous multiview background subtraction method.

• Geophysics and Geophysical Exploration
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• v.3 no.2
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• pp.48-52
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• 2000

We have calculated and analyzed the electromagnetic responses of buried conductive pipes due to a horizontal magnetic dipole source on the pound using a three-dimensional (3-D) finite element method to provide useful guidelines for designing electromagnetic pipe locator and for field operation of the system. For single buried pipe, the horizontal component and the horizontal difference of the vertical component of magnetic field show peaks above the pipe. When comparing the width of response curves of both cases around the peak, horizontal difference of vertical component of magnetic field shows much narrower peak, 2 times narrower at a half of maximum amplitude, than that of horizontal component of magnetic field. Accordingly, we can pinpoint the horizontal location of pipe on the ground more accurately by measuring the horizontal difference of vertical component of magnetic fold. Moreover, it will have a merit in determining the depth of pipe, because the equation for depth estimation is defined just above the pipe. When there are two buried pipes separated by two meters with each other, the response of horizontal difference of vertical component of magnetic field has two separate peaks each of which is located above the pipe whereas horizontal magnetic field response has only one peak above the pipe just below the transmitter. Thus, when there exist more than a buried pipe, measuring the horizontal difference of vertical magnetic field can effectively detect not only the pipe under transmitter but also adjacent ones. The width of response curves also indicates higher resolving ability of horizontal difference of vertical component of magnetic field.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.6
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• pp.1259-1270
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• 2019

The upper bound of differential characteristic probability is mainly used to determine the number of rounds when constructing a block cipher. As the number of rounds affects the performance of block cipher, it is critical to evaluate the tight upper bound in the constructing process. In order to calculate the upper bound of differential characteristic probability, the previous searching methods for minimum number of active S-boxes constructed constraint equations for non-linear operations and linear operations, independently. However, in the case of BOGI design strategy, where linear operation is dependent on non-linear operation, the previous methods may present the less tight upper bound. In this paper, we exploit the properties of BOGI strategy to propose a new method to evaluate a tighter upper bound of differential characteristic probability than previous ones. Additionally, we mathematically proved the validity of our method. Our proposed method was applied to GIFT-64 and GIFT-128, which are based on BOGI strategy, and the upper bounds of differential characteristic probability were derived until 9 round. Previously, the upper bounds of differential characteristic probability for 7-round GIFT-64 and 9-round GIFT-128 were 2^-18.395 and 2^-26.885, respectively, while we show that the upper bounds of differential characteristic probability are more tight as 2^-19.81 and 2^-28.3, respectively.

• Korean Journal of Social Welfare Studies
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• v.42 no.4
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• pp.263-293
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• 2011

There have been many studies on the relationship between welfare states and the poverty. Yet, only a few studies have been addressed the poverty alleviation effect of public pension using difference in difference(DID). This study aims to analyze poverty alleviation effect for the old aged of public pension in 10 OECD countries using DID considering welfare states regimes. The empirical analyses are based on panel data of individuals aged 50 and over from two sources: SHARE in Europe(wave I~II) and HRS in USA(2004~2006). As a result of simple DID, this study provides evidence that the poverty rate of the old aged who has not been received the pension is increased, while the poverty rate of pensioner is sharply decreased. The anti-poverty effect of public pension using DID is 45.6% which is bigger than that of pre/post approach. The policy impact used by pre/post approach in conservative welfare regime is underestimated while those in liberal and socialist regime are overestimated. In last, GDP growth rate has not significant while public pension contributes to poverty alleviation effects of the old aged. Poverty alleviation effects of public pension are also varied with welfare state regimes. The poverty alleviation effects of public pension in conservative welfare and social democratic welfare state regime are significantly bigger than that in liberal welfare state regime.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.160-169
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• 1987

Numerical simulation of the flow of upper convected Maxwell fluid through planar 4:1 contraction has been performed using type dependent difference apprximation of vorticity equation. For creeping flow assumption, the numerical convergence has been achieved up to much higher values of elasticity parameter than those obtained by conventional finite difference method. For non-vanishing Reynolds number flow, it is shown that the corner vortices disappear, which is in good qualitative agreement with extant experimental results. In doing so, spatial distributions of stream function, vorticity and stresses are considered in relation to change of type of vorticity.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.549-557
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• 2014

Recently, analysis of bargaining game using evolutionary computation is essential issues in field of game theory. In this paper, we observe a bargaining game using co-evolution between two heterogenous artificial agents. In oder to model two artificial agents, we use a particle swarm optimization and a differential evolution. We investigate algorithm parameters for the best performance and observe that which strategy is better in the bargaining game under the co-evolution between two heterogenous artificial agents. Experimental simulation results show that particle swarm optimization outperforms differential evolution in the bargaining game.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.4
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• pp.59-64
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• 2007

In this paper, we propose a new decoding method for differentially biorthogonal chirp spread spectrum (DBO-CSS). In DBO-CSS, the information is carried on the differential phase not between the adjacent sub-chirp symbols but between the sub-chirp symbols in the same position of adjacent full-chirp symbol. So, the conventional multiple symbol differential detection (MSDD) algorithms to enhance the BER performance can not be applied to the DBO-CSS directly. In this paper, we propose a new differential detection algorithm based on a partial MSD(multiple symbol detection) and a viterbi algorithm. It is shown that the performance gain of the proposed algorithm when compared with that of the conventional detection algorithm is around 2.5dB at BER = 10-5.