• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.6
• /
• pp.842-850
• /
• 2006

The role of chlorination reactions in the formation of polychlorinated dibenzofurans (PCDFs) in a municipal waste incinerator was assessed using a chlorination model for predicting PCDF isomer distributions. Complete distributions of PCDF congeners were obtained from a stoker-type municipal waste incinerator operated under 13 test conditions. Samples were collected from the flue gas prior to the gas cleaning system. While total PCDF yields varied by a factor of five to six, the distributions of congeners were similar. A chlorination model, dependent only on the observed distribution of monochlorinated isomers, was developed to predict the distributions of poly-chlorinated isomers formed by chlorination of dibenzofuran (DF). Agreement between predicted and measured PCDF isomer distributions was high for all homologues, supporting the hypothesis that DF chlorination can play an important role in the formation of PCDF byproducts.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.3
• /
• pp.246-254
• /
• 2002

In this paper auto-tuning scheme of PID controller based on the reference model has been studied for a Process control system by immune algorithm. Up to this time, many sophisticated tuning algorithms have been tried in order to improve the PID controller performance under such difficult conditions. Also, a number of approaches have been proposed to implement mixed control structures that combine a PID controller with fuzzy logic. However, in the actual plant, they are manually tuned through a trial and error procedure, and the derivative action is switched off. Therefore, it is difficult to tune. Since the immune system possesses a self organizing and distributed memory, it is thus adaptive to its external environment and allows a PDP (Parallel Distributed Processing) network to complete patterns against the environmental situation. Simulation results reveal that reference model basd tuning by immune network suggested in this paper is an effective approach to search for optimal or near optimal process control.

• Journal of Information Technology Services
• /
• v.7 no.4
• /
• pp.21-43
• /
• 2008

This paper develops the research model for the understanding of learner's usage intention in web based collaborative learning(WBCL) system. This model is based on the Davis' Technology Acceptance Model(TAM) and Social Interactivity Theory. Data is collected 225 University students from two different institutions. They were divided into 46 groups and asked to complete an online TOEIC preparation module using WBCL systems over 4 weeks. Data were collected at three points for each participant-before, 3 weeks after, and at the end of the online module. The result show that TAM based Belief factors(Usefulness, Ease of use, Playfulenss) are important determinants of usage intention in WBCL systems. The study also found the external factors of the extended TAM to be subjective norm, leader's enthusiasm in WBCL context.

• Nuclear Engineering and Technology
• /
• v.50 no.8
• /
• pp.1306-1313
• /
• 2018

The randomness and incipient nature of certain faults in reactor systems warrant a robust and dynamic detection mechanism. Existing models and methods for fault diagnosis using different mathematical/statistical inferences lack incipient and novel faults detection capability. To this end, we propose a fault diagnosis method that utilizes the flexibility of data-driven Support Vector Machine (SVM) for component-level fault diagnosis. The technique integrates separately-built, separately-trained, specialized SVM modules capable of component-level fault diagnosis into a coherent intelligent system, with each SVM module monitoring sub-units of the reactor coolant system. To evaluate the model, marginal faults selected from the failure mode and effect analysis (FMEA) are simulated in the steam generator and pressure boundary of the Chinese CNP300 PWR (Qinshan I NPP) reactor coolant system, using a best-estimate thermal-hydraulic code, RELAP5/SCDAP Mod4.0. Multiclass SVM model is trained with component level parameters that represent the steady state and selected faults in the components. For optimization purposes, we considered and compared the performances of different multiclass models in MATLAB, using different coding matrices, as well as different kernel functions on the representative data derived from the simulation of Qinshan I NPP. An optimum predictive model - the Error Correcting Output Code (ECOC) with TenaryComplete coding matrix - was obtained from experiments, and utilized to diagnose the incipient faults. Some of the important diagnostic results and heuristic model evaluation methods are presented in this paper.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1722-1724
• /
• 2005

The focus of this paper is to develop a mathematical model for investigating the dynamic performance of a polymer electrolyte membrane fuel cell. The model in this work is based on physical laws having clear significance in replicating the fuel cell system and can easily be used to set up different operational strategies. Simulation results display the transient behavior of the voltage within each single cell, and also within a number of such single cells combined into a fuel cell stack system. A linear as well as a nonlinear analysis of the polymer electrolyte membrane fuel cell system(PEMFC) has been discussed in order to present a complete and comprehensive view of this kind of modeling. Also, a comparison of the two kinds of analysis has been performed. Finally, the various characteristics of the fuel cell system are plotted in order to help us understand its dynamic behavior. Results indicate that there is a considerable amount of error in the modeling process if we use a linear model of the fuel cell. Thus, the nonlinearities present in the fuel cell system should be taken into account in order to obtain a better understanding of the dynamic behavior of the fuel cell system.

• Korean Management Science Review
• /
• v.20 no.2
• /
• pp.113-133
• /
• 2003

This study developed the ISM (Electronic Store Success Model) by basing upon the revised D&M IS Success Model and reflecting the characteristics of marketing and e business. The theoretical rationale of this model was as following : 1) Though the revised D&M IS Success Model (2002) must be more logical and complete model than the original D&M IS Success Model (1992), it did not reflect characteristics of marketing and e business. 2) In the marketing studios, Service Quality has been suggested as one of basic strategies for success. 3) In e business studies, Trust has been emerging as a potentially important antecedent of e loyalty. 4) There has been a paradigm shift from satisfaction to loyalty in marketing emphasis. 5) Nowadays, ERP (Enterprise Resource Planning) has been pervaded in many organizations and has supported PCA (Profit Center Accounting) or Channel based Accounting, so it has not been difficult to evaluate financial performance of Electronic Store. The ESM that has six dimensions (System Quality, information Quality. Service Quality, Trust, Loyalty, Financial Performance) and expresses the causal relationship among them was proposed and was compared with BSC (Balanced Scorecard), WebQual, and EWAM (Extended Web Assessment Method). The results showed that the ESM coincides with BSC and contains dimensions of WebQual, and EWAM.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.14 no.1
• /
• pp.28-35
• /
• 2006

Substructure coupling or component mode synthesis may be employed in the solution of dynamic problems for large, flexible structures. The model is partitioned into several subdomains, and a generalized Craig-Bampton representation is derived. In this paper the mode sets (normal modes, constraint modes) is employed for model reduction. A generalized model reduction procedure is described. Vaious reduction methods that use constraint modes is described in detail. As examples, a flexible structure and a 10 DOF damped system are analyzed. Comparison with a conventional reduction method based on a complete model is made via eigenpair and dynamic responses.

• Advances in Energy Research
• /
• v.3 no.3
• /
• pp.133-142
• /
• 2015

A large wind farm can be simplified by the aggregated wind farm models for load flow, steady and transient stability studies. When a fault (such as a short circuit) happens in a large wind farm, some of wind turbines trip while others do not. This paper is to design a controller to modify the aggregated wind farm model in the case of one or more unit removed or added from the complete model. This is without stopping the simulation process during performing the steady state and transient analysis of the whole system. This controller can modulate the status of the wind turbines in the aggregated model in a given farm according to any change in this farm. By this controller, we save effort and time to change the status of wind turbines in the aggregated model. The proposed wind farm is composed of some smaller farms of permanent magnet synchronous generators (PMSGs) and others of squirrel cage induction generators (SCIGs).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1370-1375
• /
• 2001

Substructure coupling or component mode synthesis may be employed in the solution of dynamic problems for structure. The model is partitioned into several subdomains. and a generalized Craig-Bampton representation is derived. In this paper the mode sets(normal modes. constraint modes) have been employed for model reduction. A generalized model reduction procedure has been described. Those reduction methods which adapt constraint modes have been described in detail. As examples. a flexible structure and a 10 DOF damped system are analyzed. Comparison with a conventional reduction method based on a complete model has been made via eigenpairs and dynamic responses.

• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.7
• /
• pp.872-880
• /
• 2007

The development of a Marine Engine Room Simulator system for training and research is described. Development objectives of the system are for both student training, research and development work. The system includes a distributed server/client architecture for 1 to 1, or 1 to many client simulation operation through OPC server, complete separation of visual elements from the controlling routines and the ability to work on the mathematical model independent of the controller and visual systems. A graphical user interface for the man-machine interface has been developed and the mathematical model has been updated. Various engine room operational situations can be simulated. The use of marine engine room simulator for training of sea going engineers and its competency for STCW-95 is discussed.