• Title/Summary/Keyword: Multi-dimensional Approach

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Multi-Scale Heterogeneous Fracture Modeling of Asphalt Mixture Using Microfabric Distinct Element Approach

  • Kim Hyun-Wook;Buttler William G.
    • International Journal of Highway Engineering
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    • v.8 no.1 s.27
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    • pp.139-152
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    • 2006
  • Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

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The Sloshing Effect on the Roll Motion and 2-DoF Motions of a 2D Rectangular Cylinder (2차원 사각형 주상체의 횡동요 및 2자유도 운동에 미치는 슬로싱의 영향)

  • Kim, Yun-Ho;Sung, Hong-Gun;Cho, Seok-Kyu;Choi, Hang-Shoon
    • Journal of the Society of Naval Architects of Korea
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    • v.50 no.2
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    • pp.69-78
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    • 2013
  • This study is constructed to investigate the sloshing effect on the motions of a two-dimensional rectangular cylinder experimentally and numerically. The modes of motion under consideration are sway and roll, and also experimental cases are divided by two categories; 1-DoF roll motion and 2-DoF motion (Coupling sway and roll). It is found that the sway response is considerably affected by the motion of the fluid, particularly near the sloshing natural frequency, while the roll response changes comparatively small. The dominant mode of motion is analyzed for 2-DoF experiments as well. The measured data for 1-DoF motions is compared with numerical results obtained by the Multi-modal approach. The numerical schemes vary in detail with the number of dominant sloshing modes; i.e. there is a single dominant mode for the Single-dominant method, while the Model 2 method assumes that the first two modes are superior. For the roll motion, numerical results obtained by the two different methods are relatively in good agreement with the experiments, and these two results are similar in most wave frequency range. However, the discrepancies are apparent where the fluid motion is not governed by a single mode. But both of numerical methods over-predict the motion at the vicinity of the sloshing natural frequency. In order to correct the discrepancy, the modal damping needs to be investigated more precisely. Furthermore, another multi-modal approach, such as the Boussinesq-type method, seems to be required in the region of the intermediate liquid.

The Prediction of DEA based Efficiency Rating for Venture Business Using Multi-class SVM (다분류 SVM을 이용한 DEA기반 벤처기업 효율성등급 예측모형)

  • Park, Ji-Young;Hong, Tae-Ho
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.139-155
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    • 2009
  • For the last few decades, many studies have tried to explore and unveil venture companies' success factors and unique features in order to identify the sources of such companies' competitive advantages over their rivals. Such venture companies have shown tendency to give high returns for investors generally making the best use of information technology. For this reason, many venture companies are keen on attracting avid investors' attention. Investors generally make their investment decisions by carefully examining the evaluation criteria of the alternatives. To them, credit rating information provided by international rating agencies, such as Standard and Poor's, Moody's and Fitch is crucial source as to such pivotal concerns as companies stability, growth, and risk status. But these types of information are generated only for the companies issuing corporate bonds, not venture companies. Therefore, this study proposes a method for evaluating venture businesses by presenting our recent empirical results using financial data of Korean venture companies listed on KOSDAQ in Korea exchange. In addition, this paper used multi-class SVM for the prediction of DEA-based efficiency rating for venture businesses, which was derived from our proposed method. Our approach sheds light on ways to locate efficient companies generating high level of profits. Above all, in determining effective ways to evaluate a venture firm's efficiency, it is important to understand the major contributing factors of such efficiency. Therefore, this paper is constructed on the basis of following two ideas to classify which companies are more efficient venture companies: i) making DEA based multi-class rating for sample companies and ii) developing multi-class SVM-based efficiency prediction model for classifying all companies. First, the Data Envelopment Analysis(DEA) is a non-parametric multiple input-output efficiency technique that measures the relative efficiency of decision making units(DMUs) using a linear programming based model. It is non-parametric because it requires no assumption on the shape or parameters of the underlying production function. DEA has been already widely applied for evaluating the relative efficiency of DMUs. Recently, a number of DEA based studies have evaluated the efficiency of various types of companies, such as internet companies and venture companies. It has been also applied to corporate credit ratings. In this study we utilized DEA for sorting venture companies by efficiency based ratings. The Support Vector Machine(SVM), on the other hand, is a popular technique for solving data classification problems. In this paper, we employed SVM to classify the efficiency ratings in IT venture companies according to the results of DEA. The SVM method was first developed by Vapnik (1995). As one of many machine learning techniques, SVM is based on a statistical theory. Thus far, the method has shown good performances especially in generalizing capacity in classification tasks, resulting in numerous applications in many areas of business, SVM is basically the algorithm that finds the maximum margin hyperplane, which is the maximum separation between classes. According to this method, support vectors are the closest to the maximum margin hyperplane. If it is impossible to classify, we can use the kernel function. In the case of nonlinear class boundaries, we can transform the inputs into a high-dimensional feature space, This is the original input space and is mapped into a high-dimensional dot-product space. Many studies applied SVM to the prediction of bankruptcy, the forecast a financial time series, and the problem of estimating credit rating, In this study we employed SVM for developing data mining-based efficiency prediction model. We used the Gaussian radial function as a kernel function of SVM. In multi-class SVM, we adopted one-against-one approach between binary classification method and two all-together methods, proposed by Weston and Watkins(1999) and Crammer and Singer(2000), respectively. In this research, we used corporate information of 154 companies listed on KOSDAQ market in Korea exchange. We obtained companies' financial information of 2005 from the KIS(Korea Information Service, Inc.). Using this data, we made multi-class rating with DEA efficiency and built multi-class prediction model based data mining. Among three manners of multi-classification, the hit ratio of the Weston and Watkins method is the best in the test data set. In multi classification problems as efficiency ratings of venture business, it is very useful for investors to know the class with errors, one class difference, when it is difficult to find out the accurate class in the actual market. So we presented accuracy results within 1-class errors, and the Weston and Watkins method showed 85.7% accuracy in our test samples. We conclude that the DEA based multi-class approach in venture business generates more information than the binary classification problem, notwithstanding its efficiency level. We believe this model can help investors in decision making as it provides a reliably tool to evaluate venture companies in the financial domain. For the future research, we perceive the need to enhance such areas as the variable selection process, the parameter selection of kernel function, the generalization, and the sample size of multi-class.

Structural Response Analysis of a Tension Leg Platform in Multi-directional Irregular Waves (다방향 불규칙파중의 인장계류식 해양구조물의 구조응답 해석)

  • Lee, Soo-Lyong;Suh, Kyu-Youl;Lee, Chang-Ho
    • Journal of Navigation and Port Research
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    • v.31 no.8
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    • pp.675-681
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    • 2007
  • A numerical procedure is described for estimating the effects of the multi-directional irregular waves on the structural responses of the Tension Leg Platform (TLP). The numerical approach is based on a three dimensional source distribution method for hydrodynamic forces, a three dimensional frame analysis method for structural responses, in which the superstructure of TLP is assumed to be flexible instead of rigid. Hydrodynamic and hydrostatic forces on the submerged surface of a TLP have been accurately calculated by excluding the assumption of the slender body theory. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in structural analysis. The spectral description used in spectral analysis of directional waves for the linear system of a TLP in the frequency domain is sufficient to completely define the structural responses. This is due to both the wave inputs and responses are stationary Gaussian random process of which the statistical properties in the amplitude domain are well known. The numerical results for the linear motion responses and tension variations in regular waves are compared with the experimental and numerical ones, which are obtained in Yoshida et al.(1983). The results of comparison confirmed the validity of the proposed approach.

Identification of a Gaussian Fuzzy Classifier

  • Heesoo Hwang
    • International Journal of Control, Automation, and Systems
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    • v.2 no.1
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    • pp.118-124
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    • 2004
  • This paper proposes an approach to deriving a fuzzy classifier based on evolutionary supervised clustering, which identifies the optimal clusters necessary to classify classes. The clusters are formed by multi-dimensional weighted Euclidean distance, which allows clusters of varying shapes and sizes. A cluster induces a Gaussian fuzzy antecedent set with unique variance in each dimension, which reflects the tightness of the cluster. The fuzzy classifier is com-posed of as many classification rules as classes. The clusters identified for each class constitute fuzzy sets, which are joined by an "and" connective in the antecedent part of the corresponding rule. The approach is evaluated using six data sets. The comparative results with different classifiers are given.are given.

Nonparametric Nonlinear Model Predictive Control

  • Kashiwagi, Hiroshi;Li, Yun
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1443-1448
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    • 2003
  • Model Predictive Control (MPC) has recently found wide acceptance in industrial applications, but its potential has been much impounded by linear models due to the lack of a similarly accepted nonlinear modelling or data based technique. The authors have recently developed a new method for obtaining Volterra kernels of up to third order by use of pseudorandom M-sequence. By use of this method, nonparametric NMPC is derived in discrete-time using multi-dimensional convolution between plant data and Volterra kernel measurements. This approach is applied to an industrial polymerisation process using Volterra kernels of up to the third order. Results show that the nonparametric approach is very efficient and effective and considerably outperforms existing methods, while retaining the original data-based spirit and characteristics of linear MPC.

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Robotic Lateral Compartment Selective Neck Dissection in Well-Differentiated Thyroid Carcinoma (갑상선 분화암에서 로봇을 이용한 측경부 림프절 절제술)

  • Tae, Kyung
    • Korean Journal of Bronchoesophagology
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    • v.17 no.2
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    • pp.83-88
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    • 2011
  • Robotic thyroidectomy has been developed to minimize neck scarring, and several authors have described its feasibility and safety, and have reported surgical outcomes comparable with conventional open thyroidectomy. The da Vinci surgical system robot provides a three-dimensional $10-12{\times}$magnified view of the surgical area. It also provides hand-tremor filtration, fine motion scaling, and precise and multi-articulated hand-like motions. Recently, robotic technology has also been applied to lateral compartment neck dissection in thyroid cancer. We have developed a new novel selective neck dissection procedure by a gasless unilateral axillo-breast (GUAB) approach with a da Vinci Surgical System for well-differentiated thyroid carcinoma to avoid a long visible neck scar. Based on our early experience, robotic selective neck dissection by GUAB approach is a safe, feasible and cosmetically excellent procedure. It can be an alternative to conventional open surgery in the highly selected patients with well-differentiated thyroid carcinoma. The oncologic safety of robotic selective neck dissection should be verified with long-term follow-up data.

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A study on the User Satisfaction of Travel behavior (관광지 선택행동에 따른 만족도에 관한 연구)

  • 박신자
    • Journal of Applied Tourism Food and Beverage Management and Research
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    • v.10
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    • pp.139-158
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    • 1999
  • This study is concerned with analysis of user satisfaction for travel behavior. It is aimed at investigating the socioeconomic characteristics, motivation, and use pattern of the visitors at tour. For tourists' perception and preference analysis, multi-dimensional scaling was used. It is left that this type of marketing analysis of tourism and travel offers great potentional for those concerned with the developement and management of tourist vacation areas. First, the study demanstrated clearly that different tourist and portential visitors to a tourist area seek different benefit bundles from their vacation in a particular tourist areas. Second, it demonstrated that a benefit segmentation approach to tourism and travel would be the most effective that the demographic segmentation approach usually pursued in the tourism and travel industry. Form a methodological viewpoint, it has demonstrated an application of multidimensional scaling techniques to marketing in an important industry.

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Business Blogging e-Hub:An Innovative Approach to e-Business

  • Wang, Guo-An
    • International Commerce and Information Review
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    • v.7 no.4
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    • pp.23-36
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    • 2005
  • With the rapid development of the Internet, e-business has been entering a new phase. However, there're still some problems to be settled and needs for breakthrough. The paper proposes an innovative approach to e-business models with the aim to resolve the problems. The paper reviews the exiting e-commerce models and points out some of the common weaknesses of the models, and presents the "Business Blogging e-Hub"model for e-business. With the characteristics of all-sided information, multi-dimensional interactivity and trans-model e-commerce platform, the proposed model is created and derived from the integration of the "classical"e-commerce models as B2B, B2C and C2C with the technology and essence of blogging, and is thus sure to meet rapidly changing business needs.

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Design of Intelligent Material Quality Control System based on Pattern Analysis using Artificial Neural Network (인공 신경망의 패턴분석에 근거한 지능적 부품품질 관리시스템의 설계)

  • 이장희;유성진;박상찬
    • Journal of Korean Society for Quality Management
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    • v.29 no.4
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    • pp.38-53
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    • 2001
  • In resolving industrial quality control problems, a vector of multiple quality characteristic variables is involved rather than a single variable. However, it is not guaranteed that a multivariate control chart based on statistical methods can monitor abnormal signal in case that small changes of relationship between each variables causes abnormal production process. Hence a quality control system for real-time monitoring of the multi-dimensional quality characteristic vector under a multivariate normal process is needed to enhance tile production system quality performance. A pattern analysis approach based on self-organizing map (SOM), an unsupervised learning technique of neural network, is applied to the design of such a quality control system. In this study we present a new material quality control system based on pattern analysis approach and illustrate the effectiveness of proposed system using actual electronic company material data.

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