• Title/Summary/Keyword: Element Elimination Method

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Stability of Continuous Welded Rail Track under Thermal Load (온도하중을 고려한 장대레일 궤도의 안정성 해석)

  • Kang, Young Jong;Lim, Nam Hyoung;Shin, Jeong Ryol;Yang, Jae Seong
    • Journal of Korean Society of Steel Construction
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    • v.11 no.3 s.40
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    • pp.281-290
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    • 1999
  • For many decades, the railway was constructed using tracks with jointed rails of relatively short lengths in accordance with rolling and handling technology. The joints cause many drawbacks in the track and lead to significant maintenance cost. So, railroad engineers became interested in eliminating joints to increase service loads ana speeds by improving rolling, welding, and fastening technology. Continuous welded rail(CWR) track has many advantages over the conventional jointed-rail track. But, in the case of the elimination of rail joints, it may cause the track to be suddenly buckled laterally by thermal loads. In this paper, CWR track model and CWRB program are developed for linear buckling analysis using finite element method. Rail element with a total of 14 degrees of freedom is used. The stiffness of the fastener, tie, and ballast bed are included by a set of spring elements. The investigation on the buckling modes and temperature of CWR track is presented.

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Three Dimensional Buckling Analysis of Continuous Welded Rail Track Under Thermal Load (온도하중을 고려한 장대레일 궤도의 3차원 좌굴 거동)

  • 강준석;임남형;양신추;강영종
    • Proceedings of the KSR Conference
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    • 2000.05a
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    • pp.471-478
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    • 2000
  • For many decades, the railway was constructed using tracks with jointed rails of relatively short lengths. The joints cause many drawbacks in the track and lead to signeficant maintenance cost. so, railroad engineers became interested in eliminating joints. Continuous welded rail(CWR) track has many advantages over the conventional jointed-rail track. but, in the case of the elimination of rail joints, it may cause the track to be suddenly buckled laterally by thermal loads. In this paper, firstly, 3-D CWR track model and CWRB program exactly considering the influence of tie are developed far linear static and buckling analysis using finite element method. Characteristics of CWR track model are using 7-dofs beam element as rail, Offset technic exactly considering centroid axies difference of track components(rail, rail-pad-fastener, tie), and Thermal gradient considering thermal difference of top flange and bottom flange in rail section.. second,, Through the static and linear buckling analysis by CWRB, Influences of various track components (rail, ballast, fastener, tie and so on..) on CWR track behavior and stability was characterized.

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Finite Difference Nonlinear Analysis of Composite Plate Structures with Various Layer Sequences (다양한 적층 배열을 갖는 복합 신소재 판 구조물의 유한차분 비선형 해석)

  • Lee, Sang Bum;Lee, Sang Youl;Lee, Rae Chul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.4
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    • pp.159-168
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    • 2005
  • This study carries out a finite difference nonlinear analysis of anisotropic advanced composite plate structures with various layer sequences. In the numerical analysis of various mechanical problems involving complex partial differential equations, the finite difference method (FDM) developed in this study has an advantage over the finite element method in its ability to avoid mesh generation and numerical integration. Many studies in FDM have been made on clamped or simple boundary conditions using merely an energy approach. These approaches cannot be satisfied, however, with pivotal points along the free boundary. Therefore, this study addresses the nonlinear problem of anisotropic plates by adopting a finite difference modeling elimination of pivotal difference points in the case of a free boundary condition. Complex nonlinear behaviors of composite plate structures for various parameters, especially for layer sequences, are analyzed using the proposed approach.

The Study on New Radiating Structure with Multi-Layered Two-Dimensional Metallic Disk Array for Shaping flat-Topped Element Pattern (구형 빔 패턴 형성을 위한 다층 이차원 원형 도체 배열을 갖는 새로운 방사 구조에 대한 연구)

  • 엄순영;스코벨레프;전순익;최재익;박한규
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.7
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    • pp.667-678
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    • 2002
  • In this paper, a new radiating structure with a multi-layered two-dimensional metallic disk array was proposed for shaping the flat-topped element pattern. It is an infinite periodic planar array structure with metallic disks finitely stacked above the radiating circular waveguide apertures. The theoretical analysis was in detail performed using rigid full-wave analysis, and was based on modal representations for the fields in the partial regions of the array structure and for the currents on the metallic disks. The final system of linear algebraic equations was derived using the orthogonal property of vector wave functions, mode-matching method, boundary conditions and Galerkin's method, and also their unknown modal coefficients needed for calculation of the array characteristics were determined by Gauss elimination method. The application of the algorithm was demonstrated in an array design for shaping the flat-topped element patterns of $\pm$20$^{\circ}$ beam width in Ka-band. The optimal design parameters normalized by a wavelength for general applications are presented, which are obtained through optimization process on the basis of simulation and design experience. A Ka-band experimental breadboard with symmetric nineteen elements was fabricated to compare simulation results with experimental results. The metallic disks array structure stacked above the radiating circular waveguide apertures was realized using ion-beam deposition method on thin polymer films. It was shown that the calculated and measured element patterns of the breadboard were in very close agreement within the beam scanning range. The result analysis for side lobe and grating lobe was done, and also a blindness phenomenon was discussed, which may cause by multi-layered metallic disk structure at the broadside. Input VSWR of the breadboard was less than 1.14, and its gains measured at 29.0 GHz. 29.5 GHz and 30 GHz were 10.2 dB, 10.0 dB and 10.7 dB, respectively. The experimental and simulation results showed that the proposed multi-layered metallic disk array structure could shape the efficient flat-topped element pattern.

Characteristics of Harbor Resonance in Donghae Harbor (Part 2. Numerical Calculation) (동해항(東海港)의 부진동(副振動) 특성(特性)(2. 수치계산(數値計算)))

  • Jeong, Weon Mu;Jung, Kyung Tae;Chae, Jang Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.3
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    • pp.185-192
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    • 1993
  • A numerical model has been used for the prediction of wave agitations in a harbor which are induced by the intrusion and transformation of incident waves. Based on linear wave theory a mild-slope equation has been used. A partial absorbing boundary condition has been used on solid boundary. Functional has been derived following Chen and Mei(l974)'s technique based on Hybrid Element Method which uses finite discretisation in the inner region and analytical solution of Helmholtz equation in the outer region. Final simultaneous equation has been solved using the Gaussian Elimination Method. Helmholtz natural period and second peak period of seiche in Donghae Harbor coincide very well with the results from numerical calculation. Computed amplification factors show good agreement, especially when the reflection coefficient on solid boundary is 0.99, with those of measurements.

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Salt and Pepper Noise Remove Considering High Frequency Region (고주파 영역을 고려한 Salt and Pepper 잡음 제거)

  • Cheon, Bong-Won;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2018.10a
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    • pp.530-532
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    • 2018
  • Digital imaging equipment has been used for a variety of purposes in a wide range of society and has become an important element of the fourth industrial revolution. However, there are various causes of noise in the process of transmitting / receiving data and processing of the equipment, thus affecting the accuracy and reliability of the equipment. In this paper, we propose an image restoration algorithm based on pixel range set by standard deviation to effectively remove Salt and Pepper noise. In the conventional methods, the performance degrades in the edge and high frequency components of the image. However, the proposed method has better noise reduction performance than the conventional method by performing the noise elimination considering the image boundary. It has confirmed that the performance of such PSNR and magnified image, the experimental results showed that the proposed algorithm superior compared to existing methods.

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FE-Analysis on void closure behavior during hot open die forging process (열간 자유단조 공정시 내부 기공 압착 거동에 관한 해석)

  • Kwon, Y.C.;Lee, J.H.;Lee, S.W.;Jung, Y.S.;Kim, N.S.;Lee, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.160-164
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    • 2007
  • In the steel industry, there is a need to produce large forged parts for the automobile industries, the flight and shipping industries ad military industries. In the steel-industry application, a cogging technique for cast ingots is required, because the major parts are needed as one large body in order to obtain higher quality. Therefore, cogging process is the primary step in manufacturing of practically large open-die forging. In the cogging process, internal voids have to be eliminated as defects, The present work is concerned with the elimination of the internal voids in large ingots so as obtain sound products. In this study, hot compression tests were carried out to obtain the flow stress of cast microstructure at different temperature and strain rates. The FEM analysis are performed to investigate the overlap defect of cast ingots during cogging stage. The measure flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the analysis of void closure are performed by using the $DEFORM^{TM}$-3D. The calculated results of void closure behavior are compared with the measured results before and after cogging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the void closure can be investigated by the comparison of practical experiment and numerical analysis.

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Studies on Cysteine desulfhydrase Produced by Bacteria(Part II) Enzymatic Preparation of L-Cysteine Derivatives by Cysteinedesulfhydrase from Aerobacter aerogenes. (Bacteria가 생산하는 Cysteinedesulfhydrase에 관한 연구(제이보) L-Cysteine 유도체의 효소적 합성에 관하여)

  • 최용진;양한철
    • Microbiology and Biotechnology Letters
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    • v.2 no.1
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    • pp.45-50
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    • 1974
  • 1 With cysteinedesulfhydrase (E. C.4.4.1.1.) from Aerobactor aerogenes, an enzyme which catalyzes the stoichiometric conversion of L-cysteine to pyruvate, ammonia and sulfide, reversibility of the degradation of L-cysteine was investigated. It was found that the enzyme also catalized the reverse reaction of $\alpha$, $\beta$-elimination to synthesize L-cysteine derivatives from pyruvate, ammonia and sulfides when large amounts of substrates were added to the reaction mixtures. 2. The synthetic reaction by cysteinedesulfhydrase proceeded linearly with incubation time and enzyme concentrations. The optimal pH for the synthetic reaction was 10.0. 3. The results of the isolation and identification of the products showed that the L-cysteine derivatives synthesized by this enzymatic method were identical with S-methyl-L-cysteine and S-ethyl-L-cysteine respectively.

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A study on Cavity Closure Behavior During Hot Open Die Forging Process (열간 자유단조 공정시 내부 공극 압착 거동에 관한 연구)

  • Kwon, Y.C.;Lee, J.H.;Lee, S.W.;Jung, Y.S.;Kim, N.S.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.16 no.4 s.94
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    • pp.293-298
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    • 2007
  • Recently, there is a need to produce a large forged part for the flight, shipping, some energies, and military industries, etc. Therefore, an open die forging technique of cast ingots is required to obtain higher quality of large size forged parts. Cogging process is one of the primary stages in many open die forging processes. In the cogging process prior to some open die forging processes, internal cavities have to be eliminated for defect-free. The present work is concerned with the elimination of the internal cavities in large ingots so as to obtain sound products. In this study, hot compression tests were carried out to obtain the flow stress of cast microstructure at different temperature and strain rates. The FEM analysis is performed to investigate the overlap defect of cast ingots during cogging stage. The measured flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the analysis of cavity closure is performed by using the $DEFORM^{TM}-3D$. The calculated results of cavity closure behavior are compared with the measured results before and after cogging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the cavity closure can be investigated by the comparison between practical experiment and numerical analysis.

The R-V Characteristics of $SiO_2 $ & $SiO_2/TiN$ Thin Film Fabricated by RF Sputtering (RF Sputtering으로 제작한 $SiO_2 $$SiO_2/TiN$ 박막의 R-V 특성)

  • 김창석;하충기;김병인
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.826-832
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    • 1998
  • In this study the thin films with the structure of Si+SiO$_2$+TiN are made by RF supttering method. TiN, which has small diffusion coefficient and low resistivity, is evaporated between SiO$_2$ and Al layers. It investigates the V-R characteristics depending on the thickness of SiO$_2$ which is used as insulation layer and researches its effects on voltage stability of thin film and varistor. These films show very small resistance valus in negative(-) voltage and large and large value in positive voltage band, and with the increase of voltage, resistance value is rapidly reduced and the satisfactory characteristic of varistor is shown at +1[V]. It is found that resistance value of TiN thin film is small and also TiN thin film has more current than the thin film which is not evaporated by TiN thin film. When Al electrode is evaporated of SiO$_2$ thin film, spiking occurs, but the spiking can be prevented with evaporation of TiN between SiO$_2$ and Al layers and this thin films in made easily because of its good attachment. With the increase of voltage, the resistance is changed into non-linear pattern and the bidirectional varistor characteristic is shown and then its theory can be verified by this experiment. Accordingly, when TiN is evaporated of Si Wafer(n-100), it obtains better voltage-resistance than thin film which is not evaporated and also when varistor character is used electrically to automatic control element such as elimination of flame, power distribution arrestor and constant voltage compensation, satisfactory reproducibilities are expected.

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