• Title/Summary/Keyword: sigmoid model

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Sigmoid Curve Model for Software Test-Effort Estimation (소프트웨어 시험 노력 추정 시그모이드 모델)

  • Lee, Sang-Un
    • The KIPS Transactions:PartD
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    • v.11D no.4
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    • pp.885-892
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    • 2004
  • Weibull distribution Iincluding Rayleigh and Exponential distribution is a typical model to estimate the effort distribution which is committed to the software testing phase. This model does not represent standpoint that many efforts are committed actually at the test beginning point. Moreover, it does not properly represent the various distribution form of actual test effort. To solve these problems, this paper proposes the Sigmoid model. The sigmoid function to be applicable in neural network transformed into the function which properly represents the test effort of software in the model. The model was verified to the six test effort data which were got from actual software projects which have various distribution form and verified the suitability. The Sigmoid model nay be selected by the alternative of Weibull model to estimate software test effort because it is superior than the Weibull model.

The Sigmoid Kinetics of Mass-action and Photosynthesis based on Influx and Efflux in a Plant Bio-system (유출입의 원리에 의한 물질대사와 광합성능에 관한 동력학적 연구)

  • 장남기
    • The Korean Journal of Ecology
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    • v.1 no.1
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    • pp.3-10
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    • 1977
  • The sigmoiod kinetics of mass-action in a biosystem have been studied by theoretical bases on the carrier hypothesis of influx and efflux of substrates. The sigmoid kinetic equations of assimilation and dissimilation rates indicate that each trophicfactor and each bio-factor behave according to the sigmoid kinetic equation and the bell shape case, and all of them are multiplicative. The general sigmoid kinetics of mass-action is given by the equation (30) which is determined by the total of the equation (28) of the assimilation rate and the equation (29) of the dissimilation rate. The sigmoid kinetic model of photosynthesis has been derived from the general equation of the sigmoid kinetics of mass-action.

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Precise Edge Detection Method Using Sigmoid Function in Blurry and Noisy Image for TFT-LCD 2D Critical Dimension Measurement

  • Lee, Seung Woo;Lee, Sin Yong;Pahk, Heui Jae
    • Current Optics and Photonics
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    • v.2 no.1
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    • pp.69-78
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    • 2018
  • This paper presents a precise edge detection algorithm for the critical dimension (CD) measurement of a Thin-Film Transistor Liquid-Crystal Display (TFT-LCD) pattern. The sigmoid surface function is proposed to model the blurred step edge. This model can simultaneously find the position and geometry of the edge precisely. The nonlinear least squares fitting method (Levenberg-Marquardt method) is used to model the image intensity distribution into the proposed sigmoid blurred edge model. The suggested algorithm is verified by comparing the CD measurement repeatability from high-magnified blurry and noisy TFT-LCD images with those from the previous Laplacian of Gaussian (LoG) based sub-pixel edge detection algorithm and error function fitting method. The proposed fitting-based edge detection algorithm produces more precise results than the previous method. The suggested algorithm can be applied to in-line precision CD measurement for high-resolution display devices.

Error Reduction of Sliding Mode Control Using Sigmoid-Type Nonlinear Interpolation in the Boundary Layer

  • Kim, Yoo-K.;Jeon, Gi-J.
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1810-1815
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    • 2003
  • Sliding mode control with nonlinear interpolation in the boundary layer is proposed. A modified sigmoid function is used for nonlinear interpolation in the boundary layer and its parameter is tuned by a fuzzy logic controller. The fuzzy logic controller that takes the distance between the system state and the sliding surface as its input guides the choice of parameter of the modified sigmoid function and the parameter is on-line tuned. Owing to the decreased thickness, the proposed method has better tracking performance than the conventional linear interpolation method. To demonstrate its performance, the proposed control algorithm is applied to a simple nonlinear system model.

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A Study of Freshman Dropout Prediction Model Using Logistic Regression with Shift-Sigmoid Classification Function (시프트 시그모이드 분류함수를 가진 로지스틱 회귀를 이용한 신입생 중도탈락 예측모델 연구)

  • Kim Donghyung
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.19 no.4
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    • pp.137-146
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    • 2023
  • The dropout of university freshmen is a very important issue in the financial problems of universities. Moreover, the dropout rate is one of the important indicators among the external evaluation items of universities. Therefore, universities need to predict dropout students in advance and apply various dropout prevention programs targeting them. This paper proposes a method to predict such dropout students in advance. This paper is about a method for predicting dropout students. It proposes a method to select dropouts by applying logistic regression using a shift sigmoid classification function using only quantitative data from the first semester of the first year, which most universities have. It is based on logistic regression and can select the number of prediction subjects and prediction accuracy by using the shift sigmoid function as an classification function. As a result of the experiment, when the proposed algorithm was applied, the number of predicted dropout subjects varied from 100% to 20% compared to the actual number of dropout subjects, and it was found to have a prediction accuracy of 75% to 98%.

Autonomous Driving Acceleration Estimation Model According to the Slope of the Road (도로의 경사도에 따른 자율주행 가속도 추정 모델)

  • Park, KyeoungWook;Heo, Myungseon;Oh, Youngchul;Han, Jihyeong;Jeong, HwaHyen;You, Byungyong
    • IEMEK Journal of Embedded Systems and Applications
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    • v.16 no.6
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    • pp.285-292
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    • 2021
  • Autonomous vehicles are divided into an upper controller that calculates control value through cognitive judgment and a lower controller that appropriately transmits its control value to an actuator. Here, the longitudinal control in a lower controller has a problem as the road slopes due to the property of the Acceleration sensor to output the acceleration as the slope of the device. Therefore, in this paper, a sigmoid function is proposed to determine the slope to compensate for this problem. Through the experiment, Checked performance by comparing the existing table model with the proposed model.

Wave dispersion properties in imperfect sigmoid plates using various HSDTs

  • Batou, Belaid;Nebab, Mokhtar;Bennai, Riadh;Atmane, Hassen Ait;Tounsi, Abdeldjebbar;Bouremana, Mohammed
    • Steel and Composite Structures
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    • v.33 no.5
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    • pp.699-716
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    • 2019
  • In this paper, wave propagations in sigmoid functionally graded (S-FG) plates are studied using new Higher Shear Deformation Theory (HSDT) based on two-dimensional (2D) elasticity theory. The current higher order theory has only four unknowns, which mean that few numbers of unknowns, compared with first shear deformations and others higher shear deformations theories and without needing shear corrector. The material properties of sigmoid functionally graded are assumed to vary through thickness according sigmoid model. The S-FG plates are supposed to be imperfect, which means that they have a porous distribution (even and uneven) through the thickness of these plates. The governing equations of S-FG plates are derived employed Hamilton's principle. Using technique of Navier, differential equations of S-FG in terms displacements are solved. Extensive results are presented to check the efficient of present methods to predict wave dispersion and velocity wave in S-FG plates.

Effect of material transverse distribution profile on buckling of thick functionally graded material plates according to TSDT

  • Abdelrahman, Wael G.
    • Structural Engineering and Mechanics
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    • v.74 no.1
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    • pp.83-90
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    • 2020
  • Several classical and higher order plate theories were used to study the buckling of functionally graded material (FGM) plates. In the great majority of research, a power function is used to represent metal and ceramic material transverse distribution (P-FGM). Therefore, the effect of having other transverse variation of material properties on the buckling behavior of thick rectangular FGM plates was not properly addressed. In the present work, this effect is investigated using the Third order Shear Deformable Theory (TSDT) for the case of simply supported FGM plate. Both a sigmoid function and an exponential functions are used to represent the transverse gradual property variation. The plate governing equations are combined with a Navier type expanded solution of the unknown displacements to derive the buckling equation in terms of the pre-buckling in-plane loads. Finally, the critical in-plane load is calculated for the different buckling modes. The model is verified by a comparison of the calculated buckling loads with available published results of Al-SiC P-FGM plates. The conducted parametric study shows that manufacturing FGM plates with sigmoid variation of properties in the thickness direction increases the buckling load considerably. This improvement is found to be more significant for the case of thick plates than that of thin plates. Results also show that this stiffening-like effect of the sigmoid function profile is more evident for cases where the in-plane loads are applied along the shorter edge of the plate.

A Historical Review on Discrete Models of Population Changes and Illustrative Analysis Methods Using Computer Softwares (개체 수 변화에 대한 이산적 모델의 역사적 개요와 컴퓨터 소프트웨어를 이용하는 시각적 분석 방법)

  • Shim, Seong-A
    • Journal for History of Mathematics
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    • v.27 no.3
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    • pp.197-210
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    • 2014
  • Species like insects and fishes have, in many cases, non-overlapping time intervals of one generation and their descendant one. So the population dynamics of such species can be formulated as discrete models. In this paper various discrete population models are introduced in chronological order. The author's investigation starts with the Malthusian model suggested in 1798, and continues through Verhulst model(the discrete logistic model), Ricker model, the Beverton-Holt stock-recruitment model, Shep-herd model, Hassell model and Sigmoid type Beverton-Holt model. We discuss the mathematical and practical significance of each model and analyze its properties. Also the stability properties of stationary solutions of the models are studied analytically and illustratively using GSP, a computer software. The visual outputs generated by GSP are compared with the analytical stability results.

An improved plasma model by optimizing neuron activation gradient (뉴런 활성화 경사 최적화를 이용한 개선된 플라즈마 모델)

  • 김병환;박성진
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.20-20
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    • 2000
  • Back-propagation neural network (BPNN) is the most prevalently used paradigm in modeling semiconductor manufacturing processes, which as a neuron activation function typically employs a bipolar or unipolar sigmoid function in either hidden and output layers. In this study, applicability of another linear function as a neuron activation function is investigated. The linear function was operated in combination with other sigmoid functions. Comparison revealed that a particular combination, the bipolar sigmoid function in hidden layer and the linear function in output layer, is found to be the best combination that yields the highest prediction accuracy. For BPNN with this combination, predictive performance once again optimized by incrementally adjusting the gradients respective to each function. A total of 121 combinations of gradients were examined and out of them one optimal set was determined. Predictive performance of the corresponding model were compared to non-optimized, revealing that optimized models are more accurate over non-optimized counterparts by an improvement of more than 30%. This demonstrates that the proposed gradient-optimized teaming for BPNN with a linear function in output layer is an effective means to construct plasma models. The plasma modeled is a hemispherical inductively coupled plasma, which was characterized by a 24 full factorial design. To validate models, another eight experiments were conducted. process variables that were varied in the design include source polver, pressure, position of chuck holder and chroline flow rate. Plasma attributes measured using Langmuir probe are electron density, electron temperature, and plasma potential.

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