• Title, Summary, Keyword: cross-gradient

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A WEIGHTED GLOBAL GENERALIZED CROSS VALIDATION FOR GL-CGLS REGULARIZATION

  • Chung, Seiyoung;Kwon, SunJoo;Oh, SeYoung
    • Journal of the Chungcheong Mathematical Society
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    • v.29 no.1
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    • pp.59-71
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    • 2016
  • To obtain more accurate approximation of the true images in the deblurring problems, the weighted global generalized cross validation(GCV) function to the inverse problem with multiple right-hand sides is suggested as an efficient way to determine the regularization parameter. We analyze the experimental results for many test problems and was able to obtain the globally useful range of the weight when the preconditioned global conjugate gradient linear least squares(Gl-CGLS) method with the weighted global GCV function is applied.

An experimental and numerical study on temperature gradient and thermal stress of CFST truss girders under solar radiation

  • Peng, Guihan;Nakamura, Shozo;Zhu, Xinqun;Wu, Qingxiong;Wang, Hailiang
    • Computers and Concrete
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    • v.20 no.5
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    • pp.605-616
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    • 2017
  • Concrete filled steel tubular (CFST) composite girder is a new type of structures for bridge constructions. The existing design codes cannot be used to predict the thermal stress in the CFST truss girder structures under solar radiation. This study is to develop the temperature gradient curves for predicting thermal stress of the structure based on field and laboratory monitoring data. An in-field testing had been carried out on Ganhaizi Bridge for over two months. Thermal couples were installed at the cross section of the CFST truss girder and the continuous data was collected every 30 minutes. A typical temperature gradient mode was then extracted by comparing temperature distributions at different times. To further verify the temperature gradient mode and investigate the evolution of temperature fields, an outdoor experiment was conducted on a 1:8 scale bridge model, which was installed with both thermal couples and strain gauges. The main factors including solar radiation and ambient temperature on the different positions were studied. Laboratory results were consistent with that from the in-field data and temperature gradient curves were obtained from the in-field and laboratory data. The relationship between the strain difference at top and bottom surfaces of the concrete deck and its corresponding temperature change was also obtained and a method based on curve fitting was proposed to predict the thermal strain under elevated temperature. The thermal stress model for CFST composite girder was derived. By the proposed model, the thermal stress was obtained from the temperature gradient curves. The results using the proposed model were agreed well with that by finite element modelling.

Complexity Reduction of Blind Algorithms based on Cross-Information Potential and Delta Functions (상호 정보 포텐셜과 델타함수를 이용한 블라인드 알고리듬의 복잡도 개선)

  • Kim, Namyong
    • Journal of Internet Computing and Services
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    • v.15 no.3
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    • pp.71-77
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    • 2014
  • The equalization algorithm based on the cross-information potential concept and Dirac-delta functions (CIPD) has outstanding ISI elimination performance even under impulsive noise environments. The main drawback of the CIPD algorithm is a heavy computational burden caused by the use of a block processing method for its weight update process. In this paper, for the purpose of reducing the computational complexity, a new method of the gradient calculation is proposed that can replace the double summation with a single summation for the weight update of the CIPD algorithm. In the simulation results, the proposed method produces the same gradient learning curves as the CIPD algorithm. Even under strong impulsive noise, the proposed method yields the same results while having significantly reduced computational complexity regardless of the number of block data, to which that of the e conventional algorithm is proportional.

A Study on Outlet Damage Prediction of Pipe Culverts in Forest Road (임도 횡단배수구의 유출구 피해 예측에 관한 연구)

  • Kim, Myung Hwan;Hwang, Jin Seong;Yu, Young Min;Cha, Du Song
    • Journal of Korean Society of Forest Science
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    • v.107 no.3
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    • pp.278-286
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    • 2018
  • This study examined the damage characteristics through investigation for a total of 10 factors (longitudinal position, crossing position, soil type, collecting well volume, outlet position, water apron material, waterway existence, pipe culvert diameter, pipe culvert gradient, pipe culvert height) affecting outlet damages of forest road cross drainage for forest roads in the Research Forest of Kangwon National University. We predicted outlet damages of forest road cross drainage for forest roads using a discriminant analysis Results showed that longitudinal position, crossing position, soil type and pipe culvert height did not affect damages caused to forest road cross drainage. Most influential factors affecting outlet damages were outlet position, waterway existence, pipe culvert diameter, pipe culvert gradient and collecting well volume, respectively. The discriminant ratio calculated from the developed discriminant function was 68.8% which is reasonably reliable.

Hydroforming of a Non-axisymmetric Thin-walled Tubular Component with Variable Cross Sections (가변 단면을 가지는 비대칭 얇은 관 부품의 액압성형 연구)

  • Kang, H.S.;Joo, B.D.;Hwang, T.W.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.24 no.5
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    • pp.368-374
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    • 2015
  • Hydroforming of a non-axisymmetric thin-walled tubular component with variable cross sections was analyzed. In order to solve the sealing problem which occurred due to the thin and non-axisymmetric shape, the use of a lead patch on the punch, which had been successful in hydroforming of thin tubes, was evaluated. A lead patch was attached to the punch to solve the sealing problem, which was caused by the stress gradient in the non-axisymmetric shape. FEM and experiments were also performed to analyze these sealing problems associated with the punch shape and non-axisymmetric shape. Finally, the lead patch was attached at tube surface where intensive local strain concentration would occur to enhance the hydroformability. These methods were successfully used to fabricate non-axisymmetric thin-walled tubular component with variable cross sections that had previously failed during traditional hydroforming.

Cross-Layer and End-to-End Optimization for the Integrated Wireless and Wireline Network

  • Gong, Seong-Lyong;Roh, Hee-Tae;Lee, Jang-Won
    • Journal of Communications and Networks
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    • v.14 no.5
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    • pp.554-565
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    • 2012
  • In this paper, we study a cross-layer and end-to-end optimization problem for the integrated wireless and wireline network that consists of one wireline core network and multiple wireless access networks. We consider joint end-to-end flow control/distribution at the transport and network layers and opportunistic scheduling at the data link and physical layers. We formulate a single stochastic optimization problem and solve it by using a dual approach and a stochastic sub-gradient algorithm. The developed algorithm can be implemented in a distributed way, vertically among communication layers and horizontally among all entities in the network, clearly showing what should be done at each layer and each entity and what parameters should be exchanged between layers and between entities. Numerical results show that our cross-layer and end-to-end optimization approach provides more efficient resource allocation than the conventional layered and separated optimization approach.

Shape Optimal Design of Elastic Concrete Dam (탄성콘크리트 댐의 모양최적설계)

  • Yoo, Yung Myun
    • Journal of The Korean Society of Civil Engineers
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    • v.5 no.4
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    • pp.9-14
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    • 1985
  • In this research mass of a plane strain two dimensional elastic concrete dam under gravitational and hydrostatic loads is minimized, through shape optimization of the dam cross section. Cross sectional area of the dam is taken as cost function of the optimization problem while constraints on the principal stress distribution and dam thickness are imposed. Shape of the boundary of the model is chosen as design variable. Variational formulation of the optimization problem, the material derivative idea of continuum mechanics, and an adjoint variable method are employed for the shape design sensitivity calculation. Then the gradient projection algorithm is utilized to obtain an optimum design iteratively. Research results fully demonstrate that the theory and procedure adopted are quite efficient and can be applicable to a wide class of practical elastic structural design problems.

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Residual Strain Effect on Circumferential Strain on Arterial Cross-Section (동맥 전단부에 분포된 원주 변형율에 대한 잔유 변형율의 영향)

  • 황민철;신정욱
    • Journal of Biomedical Engineering Research
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    • v.16 no.3
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    • pp.325-330
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    • 1995
  • The distribution of circumferential strain of arterial cross-section Is highest at intima and lowest at adventitia. However, the circumferential strain is theoretically severe at Intima because there is strain concentration. The theoretical degree of the intimal strain can not be explained in physiological condition even though artery is physiologically normal. Physiological adaptation may be undertaken to strain concentration. However, it is not clear, yet. Residual strain of artery is eagerly studied. There is experimental evidence that residual strain exists in artery. When ring of artery is longitudinally cut, it is opened. Assumption is made that intimal strain concentration is reduced with the considel'ation of residual strain. This study experimentally attempts to quantify the effect of residual strain on circumferential strain which is determined under the assumption of zero strain with zero pressure.

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Comparison of Different CNN Models in Tuberculosis Detecting

  • Liu, Jian;Huang, Yidi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.8
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    • pp.3519-3533
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    • 2020
  • Tuberculosis is a chronic and delayed infection which is easily experienced by young people. According to the statistics of the World Health Organization (WHO), there are nearly ten million fell ill with tuberculosis and a total of 1.5 million people died from tuberculosis in 2018 (including 251000 people with HIV). Tuberculosis is the largest single infectious pathogen that leads to death. In order to help doctors with tuberculosis diagnosis, we compare the tuberculosis classification abilities of six popular convolutional neural network (CNN) models in the same data set to find the best model. Before training, we optimize three parts of CNN to achieve better results. We employ sigmoid function to replace the step function as the activation function. What's more, we use binary cross entropy function as the cost function to replace traditional quadratic cost function. Finally, we choose stochastic gradient descent (SGD) as gradient descent algorithm. From the results of our experiments, we find that Densenet121 is most suitable for tuberculosis diagnosis and achieve a highest accuracy of 0.835. The optimization and expansion depend on the increase of data set and the improvements of Densenet121.

A New Calculation Method of Equalizer algorithms based on the Probability Correlation (확률분포 상관도에 기반한 Equalizer 알고리듬의 새로운 연산 방식)

  • Kim, Namyong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.3132-3138
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    • 2014
  • In many communication systems, intersymbol interference, DC and impulsive noise are hard-to-solve problems. For the purpose of cancelling such interferences, the concept of lagged cross-correlation of probability has been used for blind equalization. However, this algorithm has a large burden of computation. In this paper, a recursive method of the algorithm based on the lagged probability correlation is proposed. The summation operation in the calculation of gradient of the cost is transformed into a recursive gradient calculation. The recursive method shows to reduce the high computational complexity of the algorithm from O(NM) to O(M) for M symbols and N block data having advantages in implementation while keeping the robustness against those interferences. From the results of the simulation, the proposed method yields the same learning performance with reduced computation complexity.