• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.418-430
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• 2014

In this paper, a modelling technique for simulating self-propelled ships in waves is presented. The flow is modelled using a RANS solver coupled with an actuator disk model for the propeller. The motion of the ship is taken into consideration in the definition of the actuator disk region as well as the advance ratio of the propeller. The RPM of the propeller is controlled using a PID-controller with constraints added on the maximum permissible RPM increase rate. Results are presented for a freely surging model in regular waves with different constraints put on the PID-controller. The described method shows promising results and allows for the studying of several factors relating to self-propulsion. However, more validation data is needed to judge the accuracy of the model.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.570-574
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• 2012

Spread of household air conditioning system is continued to be increased. Axial fan in the external unit of air conditioning system is for ventilation and air supplying unit, and the related products have been widely adopted as household electronics, automobile engine, big sized blower in factory, tunnel, and subway. In this study, commercial 3-winged propeller fan is modified to shape and modified to 2-winged fan for the airflow increase and cost reduction. Using 3D modelling, the fan shape is modified, and analysis flow is adopted to provide the way to airflow increase and reduce cost while maintaining the same wind capacity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1544-1550
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• 2010

There have been many researches applying GMDH for modelling nonlinear dynamic systems. However, these methods require a great amount of computation in return of the accuracy. Thus, in this paper, we propose a method to reduce the amount of computation in GMDH by adjusting the adopting criterion of input data in decrement while at least maintaining the accuracy. The simulation result verifies that the proposed method can successfully reduce the amount of computation without the expense of the error rate, if not significantly better.

• Computers and Concrete
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• v.10 no.5
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• pp.457-467
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• 2012

Using appropriate raw materials for cement is crucial for providing the required products. Monitoring relationships and analyzing distributions in a cement material quarry are important stages in the process. CaO, one of the substantial chemical components, is included in some raw materials such as limestone and marl; furthermore, appraising spatial assessment of this chemical component is also very critical. In this study, spatial evaluation and monitoring of CaO concentrations in a cement site are considered. For this purpose, two effective regression-based models were applied to a cement quarry located in Turkey. For the assessment, some spatial models were developed and performance comparisons were carried out. The results show that the regression-based spatial modelling is an efficient methodology and it can be employed to evaluate spatially varying relationships in a cement quarry.

• International Journal of Contents
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• v.12 no.1
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• pp.49-53
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• 2016

"Hahoe Village" in Andong region is an UNESCO World Heritage Site. It should be protected against various disasters such as fire, flooding, earthquake, etc. Among these disasters, flooding has drastic impact on the lives and properties in a wide area. Since "Hahoe Village" is adjacent to Nakdong River, it is important to monitor the water level near the village. In this paper, we developed a hydrological modelling using multi-layer perceptron (MLP) to predict the water level of Nakdong River near "Hahoe Village". To develop the prediction model, error back-propagation (EBP) algorithm was used to train the MLP with water level data near the village and rainfall data at the upper reaches of the village. After training with data in 2012 and 2013, we verified the prediction performance of MLP with untrained data in 2014.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.235-242
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• 2010

DSTC(Defense Systems Test Center) in ADD(Agency for Defense Development) performs a test for various kinds of weapon system. In order to provide accurate test measurement data relating to the weapon system's performance with customer, A reliable test process and an objective analysis of the measurement data are required. DSTC is trying to apply CMMI(Capability Maturity Model Integration) Ver 1.2 in a test process. In this paper, we present the result of CMMI Engineering Process Area Modelling of Test Process.

• Proceedings of the KIEE Conference
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• 2009.04a
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• pp.163-165
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• 2009

Many photovoltaic (PV) systems are being developed and installed. For a PV developer, simulations are required before the experimental testing. However, most simulation tools do not offer data libraries for PV systems, so that some Institutes who try to use such software will be in difficulty. In this paper, simulations of performance and stability have been carried out using the software PSPICE. In this paper, the modelling of solar cell arrays, photovoltaic modules, PV generators, batteries and drive systems is carried out based on mathematical equivalence circuits and available data, and the models are converted into a data library for PSPICE that is user friendly. System variations can be modeled by simple parameter variation. To verify the accuracy of the simulation library, various models were run and compared to known systems.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.120-124
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• 1991

In this paper, we consider the maneuvering detection and target tracking problem in uncertain linear discrete-time systems. The maneuvering detection is based on X$^{2}$ test[2,71, where Kalman filters have been utilized so far. The target tracking is performed by the maneuvering input compensation based on a maximum likelihood estimator. KF has been known to diverge when some modelling errors exist and fail to detect the maneuvering and to track the target in uncertain systems. Thus this paper adopt the FIR filter[l], which is known to be robust to modelling errors, for maneuvering detection and target tracking problem. Various computer simulations show the superior performance of the FIR filter in this problem.

• Computers and Concrete
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• v.5 no.5
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• pp.475-490
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• 2008

The paper explores the potential of applicability of Genetic programming approach (GP), adopted in this investigation, to model the combined effects of five independent variables to predict the mini-slump, the plate cohesion meter, the induced bleeding test, the J-fiber penetration value, and the compressive strength at 7 and 28 days of self-compacting slurry infiltrated fiber concrete (SIFCON). The variables investigated were the proportions of limestone powder (LSP) and sand, the dosage rates of superplasticiser (SP) and viscosity modifying agent (VMA), and water-to-binder ratio (W/B). Twenty eight mixtures were made with 10-50% LSP as replacement of cement, 0.02-0.06% VMA by mass of cement, 0.6-1.2% SP and 50-150% sand (% mass of binder) and 0.42-0.48 W/B. The proposed genetic models of the self-compacting SIFCON offer useful modelling approach regarding the mix optimisation in predicting the fluidity, the cohesion, the bleeding, the penetration, and the compressive strength.

• Earthquakes and Structures
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• v.6 no.6
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• pp.611-625
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• 2014

This paper presents a simple methodology that integrates an improved storey shear modelling, Incremental Dynamic Analysis and Monte Carlo Simulation in order to carryout vulnerability analysis towards development of fragility curves for Unreinforced Brick Masonry buildings. The methodology is demonstrated by developing fragility curves of a single storey Unreinforced Brick Masonry building for which results of experiment under lateral load is available in the literature. In the study presented, both uncertainties in mechanical properties of masonry and uncertainties in the characteristics of earthquake ground motion are included. The research significance of the methodology proposed is that, it accommodates a new method of damage grade classification which is based on 'structural performance characteristics' instead of 'fixed limiting values'. The usefulness of such definition is discussed as against the existing practice.