• Title/Summary/Keyword: Nonlinear components

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Experimental Design of S box and G function strong with attacks in SEED-type cipher (SEED 형식 암호에서 공격에 강한 S 박스와 G 함수의 실험적 설계)

  • 박창수;송홍복;조경연
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.1
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    • pp.123-136
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    • 2004
  • In this paper, complexity and regularity of polynomial multiplication over $GF({2^n})$ are defined by using Hamming weight of rows and columns of the matrix ever GF(2) which represents polynomial multiplication. It is shown experimentally that in order to construct the block cipher robust against differential cryptanalysis, polynomial multiplication of substitution layer and the permutation layer should have high complexity and high regularity. With result of the experiment, a way of constituting S box and G function is suggested in the block cipher whose structure is similar to SEED, which is KOREA standard of 128-bit block cipher. S box can be formed with a nonlinear function and an affine transform. Nonlinear function must be strong with differential attack and linear attack, and it consists of an inverse number over $GF({2^8})$ which has neither a fixed pout, whose input and output are the same except 0 and 1, nor an opposite fixed number, whose output is one`s complement of the input. Affine transform can be constituted so that the input/output correlation can be the lowest and there can be no fixed point or opposite fixed point. G function undergoes linear transform with 4 S-box outputs using the matrix of 4${\times}$4 over $GF({2^8})$. The components in the matrix of linear transformation have high complexity and high regularity. Furthermore, G function can be constituted so that MDS(Maximum Distance Separable) code can be formed, SAC(Strict Avalanche Criterion) can be met, and there can be no weak input where a fixed point an opposite fixed point, and output can be two`s complement of input. The primitive polynomials of nonlinear function affine transform and linear transformation are different each other. The S box and G function suggested in this paper can be used as a constituent of the block cipher with high security, in that they are strong with differential attack and linear attack with no weak input and they are excellent at diffusion.

Evaluation of Ductility and Strength Factors for Special Steel Moment Resisting Frames (철골 연성 모멘트 골조의 연성계수 및 강도계수 평가)

  • Kang, Cheol Kyu;Choi, Byong Jeong
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6 s.73
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    • pp.793-805
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    • 2004
  • The main objective of this paper is to evaluate the ductility and strength factors that are key components of the response modification factor for special steel moment-resistant frames. The ductility factors for special steel moment-resistant frames were calculated by multiplying the ductility factor for SDOF systems and the MDOF modification factors. Ductility factors were computed for elastic and perfectly plastic SDOF systems undergoing different levels of inelastic deformation and periods when subjected to a large number of recorded earthquake ground motions. Based on the results of the regression analysis, simplified expressions were proposed to compute the ductility factors. Based on previous studies, the MDOF modification factors were also proposed to account for the MDOF systems. Strength factors for special steel moment resisting frames were estimated from the results of the nonlinear static analysis. A total of 36 sample steel frames were designed to investigate the ductility and strength factors considering design parameters such as number of stories (4, 8, and 16 stories), seismic zone factors (Z = 0.075, 0.2, and 0.4), framing system (Perimeter Frames, PF and Distributed Frames, DF), and failure mechanism (Strong-Column Weak Beam, SCWB, and Weak-Column Strong-Beam, WCSB). The effects of these design parameters on the ductility and strength factors for special steel moment-resisting frames were investigated.

An Improved Bond Slip Model of CFT Columns for Nonlinear Finite Element Analysis (CFT 기둥의 비선형 유한요소해석을 위한 개선된 강관-콘크리트 간 부착 모델 개발)

  • Kwon, Yangsu;Kwak, Hyo-Gyoung;Hwang, Ju-Young;Kim, Jin-Kook;Kim, Jong-Min
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.2
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    • pp.213-220
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    • 2015
  • CFT column has a lot of structural advantages due to the composite behavior between in-filled concrete and steel tube. This paper deals with the development of an effective numerical model which can consider the bond-slip behavior between both components of concrete matrix and steel tube without taking double nodes. Since the applied axial load to in-filled concrete matrix is delivered to steel tube by the confinement effect and the friction, the governing equation related to the slip behavior can be constructed on the basis of the force equilibrium and the compatability conditions. In advance, the force and displacement relations between adjacent two nodes make it possible to express the slip behavior with the concrete nodes only. This model results in significant savings in the numerical modeling of CFT columns to take into account the effect of bond-slip. Finally, correlation studies between numerical results and experimental data are conducted to verifying the efficiency of the introduced numerical model.

Color Image Enhancement Based on an Improved Image Formation Model (개선된 영상 생성 모델에 기반한 칼라 영상 향상)

  • Choi, Doo-Hyun;Jang, Ick-Hoon;Kim, Nam-Chul
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.6 s.312
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    • pp.65-84
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    • 2006
  • In this paper, we present an improved image formation model and propose a color image enhancement based on the model. In the presented image formation model, an input image is represented as a product of global illumination, local illumination, and reflectance. In the proposed color image enhancement, an input RGB color image is converted into an HSV color image. Under the assumption of white-light illumination, the H and S component images are remained as they are and the V component image only is enhanced based on the image formation model. The global illumination is estimated by applying a linear LPF with wide support region to the input V component image and the local illumination by applying a JND (just noticeable difference)-based nonlinear LPF with narrow support region to the processed image, where the estimated global illumination is eliminated from the input V component image. The reflectance is estimated by dividing the input V component image by the estimated global and local illuminations. After performing the gamma correction on the three estimated components, the output V component image is obtained from their product. Histogram modeling is next executed such that the final output V component image is obtained. Finally an output RGB color image is obtained from the H and S component images of the input color image and the final output V component image. Experimental results for the test image DB built with color images downloaded from NASA homepage and MPEG-7 CCD color images show that the proposed method gives output color images of very well-increased global and local contrast without halo effect and color shift.

Demand Strength Spectrums of Low-Rise Reinforced Concrete Buildings Consisted of Extremely Brittle, Shear and Flexural Failure Systems (극취성·전단·휨파괴형 수평저항시스템으로 구성된 저층 철근콘크리트 건물의 요구 내력 스펙트럼)

  • Lee, Kang-Seok;Kim, Jeong-Hee;Oh, Jae-Keun
    • Journal of the Korea Concrete Institute
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    • v.19 no.5
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    • pp.529-537
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    • 2007
  • The purpose of this study is to discuss how strength and ductility of each system in low-rise reinforced concrete buildings composed of extremely brittle, shear and flexural failure lateral-load resisting systems have influence on seismic capacities of the overall system, which is based on nonlinear seismic response analyses of single-degree-of-freedom structural systems. In order to simulate the triple lateral-load resisting system, structures are idealized as a parallel combination of two modified origin-oriented hysteretic models and a degrading trilinear hysteretic model that fail primarily in extremely brittle, shear and flexure, respectively. Stiffness properties of three models are varied in terms of story shear coefficients, and structures are subjected to various ground motion components. By analyzing these systems, interaction curves of demand strengths of the triple system for various levels of ductility factors are finally derived for practical purposes. The result indicates that demand strength levels derived can be used as a basic information for seismic evaluation and design criteria of low-rise reinforced concrete buildings having the triple lateral-load resisting system.

A Methodology of Seismic Damage Assessment Using Capacity Spectrum Method (능력 스펙트럼법을 이용한 건물 지진 손실 평가 방법)

  • Byeon, Ji-Seok
    • Journal of the Earthquake Engineering Society of Korea
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    • v.9 no.3 s.43
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    • pp.1-8
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    • 2005
  • This paper describes a new objective methodology of seismic building damage assessment which is called Advanced Component Method(ACM). ACM is a major attempt to replace the conventional loss estimation procedure, which is based on subjective measures and the opinions of experts, with one that objectively measures both earthquake intensity and the response ol buildings. First, response of typical buildings is obtained analytically by nonlinear seismic static analysis, push-over analyses. The spectral displacement Is used as a measure of earthquake intensity in order to use Capacity Spectrum Method and the damage functions for each building component, both structural and non-structural, are developed as a function of component deformation. Examples of components Include columns, beams, floors, partitions, glazing, etc. A repair/replacement cost model is developed that maps the physical damage to monetary damage for each component. Finally, building response, component damage functions, and cost model were combined probabilistically, using Wonte Carlo simulation techniques, to develop the final damage functions for each building type. Uncertainties in building response resulting from variability in material properties and load assumptions were incorporated in the Latin Hypercube sampling technique. The paper also presents and compares ACM and conventional building loss estimation based on historical damage data and reported loss data.

Effect of Groove Shape on Residual Stress Distribution in Narrow Gap Welds (용접부 형상이 협개선 용접부 잔류응력 분포에 미치는 영향)

  • Soh, Na-Hyun;Yang, Jun-Seok;Pyo, Chang-Ryul;Huh, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.6
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    • pp.635-642
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    • 2011
  • It is well known that conventional welding techniques can result in welding defects due to the large groove angle of the weld. In this context, the narrow gap welding (NGW) technique is applied in the nuclear industry because of its inherent merits such as the reduction in welding time and the shrinkage of the weld, and the small deformation of the weld resulting from the small groove angle and welding bead width. In this paper, the distribution of welding residual stress and deformation behavior of the ER308L weld due to NGW are predicted through nonlinear two-dimensional finite element analysis, in which the actual NGW process is simulated in detail. In particular, the effects of the shape of weld, i.e., the width of the weld and the shape of the welding groove, on the residual stress are investigated. The present results can be used to assess the integrity of defective nuclear components and to improve the welding process.

Size-Reduced Ring-Hybrid Coupler Using Phase-Inverting Ultra-Wideband Transitions and Its Frequency Doubler Application (초광대역 위상 역전 전이 구조를 이용한 소형화된 링 하이브리드 결합기 및 주파수 체배기 응용)

  • Song, Sun-Young;Kim, Young-Gon;Park, Jin-Hyun;Kim, Kang-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.9
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    • pp.1037-1044
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    • 2010
  • In this paper, a new size-reduced, wideband ring-hybrid coupler is presented, and a design of a planar single-balanced doubler using the ring-hybrid is shown. This ring-hybrid coupler employs a pair of ultra-wideband transitions for phase inversion, which consists of in-phase and out of-phase transitions providing a good amplitude and phase balances for wide frequency ranges. The implemented ring-hybrid is 65 % smaller than conventional ring-hybrids, and provides 92.5 % and 81.3 % bandwidth at $\sum$ and $\Delta$ ports, respectively. Thanks to good amplitude and phase balances over wide bandwidth, the ring-hybrid can be applied to implement various balanced components. The implemented single-balanced doubler utilizing the ring-hybrid exhibits typical conversion loss of 10.5 dB for the output frequency range of 4~12 GHz with fundamental suppression level of 30 dB. The performance was also well-predicted with the nonlinear circuit simulation.

A Single Allocation Hub Network Design Model for Intermodal Freight Transportation (단일할당 복합운송 허브 네트워크 설계 모형 개발)

  • Kim, Dong-Gyu;Gang, Seong-Cheol;Park, Chang-Ho;Go, Seung-Yeong
    • Journal of Korean Society of Transportation
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    • v.27 no.1
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    • pp.129-141
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    • 2009
  • Intermodal freight transportation is defined as the movement of freight from origins to destinations by two or more transportation modes. When implemented in hub networks, it could enhance the efficiency of the networks because consolidated flows are transported by more suitable modes and technologies. In spite of this advantage, the intermodal hub network design problem has received limited attention in the literature partly because of the complex nature of the problem. This paper aims to develop an optimization model for designing intermodal hub networks with sin91e allocation strategy. The model takes into account various cost components of intermodal hub networks including transportation, stationary inventory, and service delay costs. Moreover, using transport frequency variables, it is capable of endogenously determining the transportation economies of scale achieved by consolidation of flows. As such, the model is able to realistically represent the characteristics of intermodal hub networks in practice. Since the model Is a complicated nonlinear integer programming problem, we perform model simplification based on the analytical study of the model, which could facilitate the development of solution algorithms in the future. We expect that this study contributes to the design of intermodal hub networks as well as to the assessment of existing logistics systems.

Collapse Capacity Evaluation of Steel Intermediate Moment Frames Using Incremental Dynamic Analysis (비선형 증분동적해석을 통한 철골 중간모멘트 골조의 붕괴성능 평가)

  • Shin, Dong-Hyeon;Kim, Hyung-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.2
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    • pp.9-20
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    • 2014
  • Steel intermediate moment frames (IMFs) have been generally used as seismic load resisting systems (SLRSs) of a building to provide resistances against strong ground shaking. However, most of low and mid-rise steel buildings in Korea were constructed during pre-seismic code era or before the introduction of well-organized current seismic codes. It has been recognized that the seismic performance of these steel IMFs is still questionable. In order to respond to such a question, this study quantitatively investigates the seismic capacities of steel IMFs. Prototype models are built according to the number of stories, the levels of elastic seismic design base shear and the ductilities of structural components. Also, the other prototype models employing hysteretic energy dissipating devices (HEDDs) are considered. The collapse mechanism and the seismic performance of the prototype models are then described based on the results obtained from nonlinear-static and incremental-dynamic analyses. The seismic performance of the prototype models is assessed from collapse margin ratio (CMR) and collapse probability. From the assessment, the prototype model representing new steel IMFs has enough seismic capacities while, the prototype models representing existing steel IMFs provide higher collapse probabilities. From the analytic results of the prototype models retrofitted with HEDDs, the HEDDs enhance the seismic performance and collapse capacity of the existing steel IMFs. This is due to the energy dissipating capacity of the HEDDs and the redistribution of plastic hinges.