• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.3
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• pp.43-56
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• 1982

A recursive algorithms for prediction of streamflows by Kalman filtering theory and Self-tuning predictor based on the state space description of the dynamic systems have been studied and the applicabilities of the algorithms to the rainfall-runoff processes have been investigated. For the representation of the dynamics of the processes, a low-order ARMA process has been taken as the linear discrete time system with white Gaussian disturbances. The state vector in the prediction model formulated by a random walk process. The model structures have been determined by a statistical analysis for residuals of the observed and predicted streamflows. For the verification of the prediction algorithms developed here, the observed historical data of the hourly rainfall and streamflows were used. The numerical studies shows that Kalman filtering theory has better performance than the Self-tuning predictor for system identification and prediction in rainfall-runoff processes.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.269-277
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• 2009

The current paper focuses on the analysis of transient cavitating flow in pressurised polyethylene pipes, which are characterized by viscoelastic rheological behaviour. A hydraulic transient solver that describes fluid transients in plastic pipes has been developed. This solver incorporates the description of dynamic effects related to the energy dissipation (unsteady friction), the rheological mechanical behaviour of the viscoelastic pipe and the cavitating pipe flow. The Discrete Vapour Cavity Model (DVCM) and the Discrete Gas Cavity Model (DGCM) have been used to describe transient cavitating flow. Such models assume that discrete air cavities are formed in fixed sections of the pipeline and consider a constant wave speed in pipe reaches between these cavities. The cavity dimension (and pressure) is allowed to grow and collapse according to the mass conservation principle. An extensive experimental programme has been carried out in an experimental set-up composed of high-density polyethylene (HDPE) pipes, assembled at Instituto Superior T$\acute{e}$cnico of Lisbon, Portugal. The experimental facility is composed of a single pipeline with a total length of 203 m and inner diameter of 44 mm. The creep function of HDPE pipes was determined by using an inverse model based on transient pressure data collected during experimental runs without cavitating flow. Transient tests were carried out by the fast closure of the ball valves located at downstream end of the pipeline for the non-cavitating flow and at upstream for the cavitating flow. Once the rheological behaviour of HDPE pipes were known, computational simulations have been run in order to describe the hydraulic behaviour of the system for the cavitating pipe flow. The calibrated transient solver is capable of accurately describing the attenuation, dispersion and shape of observed transient pressures. The effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient event are discussed.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.41-51
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• 1997

A dynamic mathematical model of a thermal power plant with a single drum-type boiler is described with the base on modular concept. The present process model, which is including full scope of the components and high load changes, is based on physical approach through lumped parameters. The module, which means a component of the power plant and must essentially depict the characteristics of the component well, might be interconnected using pressure nodal method in a arrangement determined by users. With the results of the load changes of 75 MW to 95 MW and 95MW to 75 MW with the rate of 3 MW/min, the applicability of the process model is examined connecting to DCS(Dispersion Control System), which has a real running logic of 100 MW real power plant.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.3
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• pp.21-28
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• 2009

The precise analysis of soil-pile-structure interaction requires a proper description of soil layer, pile, and structure. In commonly used finite element simulations, mesh boundaries should match the material discontinuity line. However, in practice, the geometry of soil profiles and piles may be so complex that mesh alignment becomes a wasteful and difficult task. To overcome these difficulties, a different integration method is adopted in this paper, which enables easy integration over a regular element with material discontinuity regardless of the location of the discontinuity line. By applying this integration method, the mesh can be generated rapidly and in a highly structured manner, leading to a very regular stiffness matrix. The influence of the shape of the soil profile and piles on the response is examined, and the validity of the proposed soil-pile structure interaction analysis method is demonstrated through several examples. It is seen that the proposed analysis method can be easily used on soil-pile-structure interaction problems with complex interfaces between materials to produce reliable results regardless of the material discontinuity line.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1522-1533
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• 1996

This paper presents a programming environment for the edition and verification of specification language SDL. It is implemented in the Concerto software factory, which has been as a support for the development of real size software. Concerto is a software factory designed for application development in the fields of computer communication protocols or real time system. It offers various kinds of tools to produce software, organize this production and automate it. Concerto allows a smooth integration of various formalism such as the C and $C^{++}$, languages, structured documentation, HOOD methodology (Hierarchical Object Orient Design). In this paper, as an important tools in the process of communication protocol software development, we describe fist describe the principles of this environment, then we illustrate its application by means of a simple example, the Inres protocol. Moreover, we study how hypertext mechanism of Concert to create logical links between a protocol and its asscoiated service.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.385-396
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• 2005

In this paper, a new structural approach to on-line signature verification is presented. A primitive pattern is defined as a part segmented by a local minimal position of speed. And a structural description of signature is composed of subpatterns which are defined as such forms as rotation shape, cusp shape and bell shape, acquired by composition of the primitives regarding the directional changes. As the matching method to find identical parts between two signatures, a modified DP(dynamic programming) matching algorithm is presented. And also, variation and complexity of local parts are computed from the training samples, and reference model and decision boundary are derived from these. Error rate, execution time and memory usage are compared among the functional approach, the parametric approach and the proposed structural approach. It is found that the average error rate can be reduced from 14.2% to 4.05% when the local parts of a signature are weighted and the complexity is used as a factor of decision threshold. Though the error rate is similar to that of functional approaches. time consumption and memory usage of the proposed structural approach are shown to be very effective.

• Korea journal of population studies
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• v.20 no.2
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• pp.5-42
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• 1997

This study contributes to understanding women's labor market behavior by focusing on a particular set of labor force transitions - labor force withdrawal and entry during the period surrounding the first birth of a child. In particular, this study provides a dynamic analyses, using longitudinal data and event history analysis, to conceptualize labor force behaviors in a straightforward way. The main research question addresses which factors increase or decrease the hazard rates of leaving and entering the labor market. This study used piecewise Gompertz model, following the guide of the non-parametric analysis on the hazard rates, which allowed relatively detailed description on the distribution of timing of leave and entry to the labor market as parameters of interest. The results show that preferences and structural variables, as well as economic considerations, are very important factors to explain the labor market behavior of women in the period surrounding childbirth.

• The Transactions of the Korea Information Processing Society
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• v.6 no.9
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• pp.2479-2492
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• 1999

Network management system(NMS) provides not only effective monitoring and controlling of network which consists of heterogeneous network elements but prompt response to users' need for high-level communication services. Recommendations of ITU-T and ISO stipulate the managerial abstraction of static and dynamic characteristics of network elements, management functions as well as management communication protocol. But the current description method does not provide the formal mechanism for the behavior characteristics of managed objects in clear manner but in natural language form, the complete specification of managed objects is not fully described. In this paper, we describe determinants for the behaviour of managed objects applicable to every managed object, and present a language for specifying behavioral aspects of managed objects based on their temporal and active properties.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1544-1572
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• 2011

Task placement and scheduling are traditionally studied in following aspects: resource utilization, application throughput, application execution latency and starvation, and recently, the studies are more on application scalability and application performance. A methodology for task placement and scheduling centered on tasks based on virtual machines is studied in this paper to improve the performances of systems and dynamic adaptability in applications development and deployment oriented parallel computing. For parallel applications with no real-time constraints, we describe a thought of feature model and make a formal description for four layers of task placement and scheduling. To place the tasks to different layers of virtual computing systems, we take the performances of four layers as the goal function in the model of task placement and scheduling. Furthermore, we take the personal preference, the application scalability for a designer in his (her) development and deployment, as the constraint of this model. The workflow of task placement and scheduling based on virtual machines has been discussed. Then, an algorithm TPVM is designed to work out the optimal scheme of the model, and an algorithm TEVM completes the execution of tasks in four layers. The experiments have been performed to validate the effectiveness of time estimated method and the feasibility and rationality of algorithms. It is seen from the experiments that our algorithms are better than other four algorithms in performance. The results show that the methodology presented in this paper has guiding significance to improve the efficiency of virtual computing systems.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.303-308
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• 2019

This study suggests a method for deriving earthquake response based on log-normal distribution in order to obtain realistic and reliable probability and statistical seismic response of structures. The development of three earthquake suites were presented, with a brief description of 2%, 10%, and 50% in 50 years probability of exceedance according the USGS Los Angeles probabilistic seismic hazard maps. In order to analyze the basic dynamic behavior, a Single-Degree-of-Freedom (SDOF) structure was selected and the seismic response spectrum representing the response of each natural period was plotted. Overall, the mean response values presented through the log-normal distribution is lower than the standard normal distribution. Thus, it is considered that the former method can be provided as the effective cost on performance-based seismic design more than the latter one.