• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.45-51
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• 2002

Recently the interest for the environment is increasing. So the criterion for the evaluation of the burner has changed. For efficient driving problem, if the thermal efficiency is higher and the oxygen in exhaust gas is lower, then burner is evaluated better. For environmental problem. burner must satisfy NOx limit, soot limit and CO limit. Generally the experienced operator judge of the combustion status of the burner by the color of flame. we don't still have any satisfactory solution against it. the relation of the combustion status and the color of the flame hasn't still been established. This paper is the study about the relation of the combustion status and the color of the flame. This paper describes development of real time flame diagnosis technique that evaluate and diagnose combustion state such as consistency of components in exhaust gas, stability of flame in quantitative sense. In this paper, it was proposed on the flame diagnosis technique of burner using image processing algorithm, the parameter extracted from the image of the flame was used as the input variables of the flame diagnostic system. at first, linear regression algorithm and multiple regression algorithm was used to obtain linear multi-nominal expression. Using the constructed inference algorithm, the amount of NOx and CO of the combustion gas was successfully inferred. the combustion control system will be realized sooner or later.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.765-772
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• 2011

In this research, the fuel cell system model capable of generating codes in real time was developed to construct of a HIL (Hardware-In-the-Loop) for a SOFC-powered ship. Moreover, the effects of the distribution of the exhaust gas flow rates in a stack, the flow rates of fuels and temperature of air supplied on the temperature characteristics of fuels supplied to the cathode and the anode, the output power of the stack and system efficiency are examined to minimize the temperature difference between fuels supplied to the stack used in a 500kW SOFC system using methane as a fuel. As a result, the temperatures of fuels supplied to the cathode and the anode maintain at 830K when the opening factor of three-way valve located at outlet of turbine is 0.839. Also the process for optimization of methane flow rate considering the fuel cell stack and system efficiency is required to increase the temperatures of fuels supplied to the stack.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.78-86
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• 2016

In this paper we propose a new frame transfer function model describing the variations of a heat release rate in response to an external flow oscillation in gas turbine systems. A critical difference of our model compared to the so-called $n-{\tau}$ model which has been widely used for a prediction of combustion instability (CI), is that our model is able to describe a nonlinear relation between phase and frequency. In contrast, the phase part of the $n-{\tau}$ model is a pure time delay and thus the phase should be a linear function of frequency, which is inconsistent with many experimental results of real combustion systems. For an illustration, our new model is applied to experimental data and the effect of phase nonlinearity is investigated in the context of combustion instability.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.17-24
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• 2016

The reacting flows of gaseous hydrogen/liquid oxygen 2D coaxial shear injector with varying recess length are numerically analyzed. The standard ${\kappa}-e$ model and laminar flamelet model are adopted for the steady turbulent combustion with the ideal and real gas equations. As the recess length increases, the recirculating region in the combustion chamber expands and the vorticity is intensified. Also, the variations of temperature, products, and pressure are strongly related to the recess length. The results show that an efficient combustor can be obtained by the introduction of the recessed injector.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.608-613
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• 2007

Prediction of corporate bankruptcies has long been an important topic and has been studied extensively in the finance and management literature because it is an essential basis for the risk management of financial institutions. Recently, support vector machines (SVMs) are becoming popular as a tool for bankruptcy prediction because they use a risk function consisting of the empirical error and a regularized term which is derived from the structural risk minimization principle. In addition, they don't require huge training samples and have little possibility of overfitting. However. in order to Use SVM, a user should determine several factors such as the parameters ofa kernel function, appropriate feature subset, and proper instance subset by heuristics, which hinders accurate prediction results when using SVM In this study, we propose a novel hybrid SVM classifier with simultaneous optimization of feature subsets, instance subsets, and kernel parameters. This study introduces genetic algorithms (GAs) to optimize the feature selection, instance selection, and kernel parameters simultaneously. Our study applies the proposed model to the real-world case for bankruptcy prediction. Experimental results show that the prediction accuracy of conventional SVM may be improved significantly by using our model.

• The Journal of Industrial Distribution & Business
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• v.11 no.11
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• pp.7-18
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• 2020

Purpose: The Emission Trading Scheme (ETS), which enables structuring emission credits as a financial product, is taking a crucial position of global collaboration against climate change. Previous studies that have covered ETS subjects from the macro perspective contribute to facilitating legal enactment of this scheme. However, they have rarely addressed challenges aligned with issues arising from labor burdens for ETS works from the business perspective. Research Design, data and methodology: This study presents conceptual models that are expected to help design an electronic system. The study model contains four modules: emission allocation, data interface, reduction technology sharing, and emission trading. Two validation approaches, the Analytic Hierarchy Process (AHP) and regression analysis, are applied in confirming the feasibility of the proposed model. Results: This study suggests an IT system methodology to help improvement of the current K-ETS mechanism. In particular, this study addresses effectiveness for real businesses and the adaptability of this mechanism to other nations. Conclusions: The proposed IT platform diagram can contribute to successful operation of ETS by providing multiple benefits to participating companies through in-house allocation mechanisms, the soft-landing of ETS adoption to participating companies through reduction of technology-sharing, group purchases, and transaction costs through the trading system.

• Journal of Astronomy and Space Sciences
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• v.10 no.2
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• pp.163-188
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• 1993

On the framework of Tolman spacetime model, the caustics around a local perturbed region in redshift is due to the local expansion rate induced by a local density inhomogeneity in real space. We have compared the caustics in redshift space, which are analytically obtained, with the observed redshift-distance patterns of galaxies which are belonging to Coma and Perseus clusters. For the Abell density distribution model and polytropic density profiles which are well-fitting the optical and X-ray observations, respectively, the size of caustics which is defined by "turnaround radius" of a local density perturbed region should give constraints on the sizes and masses of rich clusters and give also a clue to understand the state of hot X-ray emitting gas.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.12-23
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• 2014

The O&M (Operation and Maintenance) phase of offshore plants with a long life cycle requires heavy charges and more efforts than the construction phase, and the occurrence of an accident of an offshore plant causes catastrophic damage. So previous studies have focused on the development of advanced maintenance system to avoid unexpected failures. Nowadays due to the emerging ICTs (Information Communication Technologies) and sensor technologies, it is possible to gather the status data of equipment and send health monitoring data to administrator of an offshore plant in a real time way, which leads to having much concern on the condition based maintenance policy. In this study, we have reviewed previous studies associated with CBM (Condition-Based Maintenance) of offshore plants, and introduced an algorithm predicting the next failure time of the compressor which is one of essential mechanical devices in LNG FPSO (Liquefied Natural Gas Floating Production Storage and Offloading vessel). To develop the algorithm, continuous time Markov model is applied based on gathered vibration data.

• Structural Engineering and Mechanics
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• v.42 no.6
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• pp.815-829
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• 2012

This paper proposes a nonlinear computational modeling approach for the behaviors of structural systems subjected to fire. The proposed modeling approach consists of fire dynamics analysis, nonlinear transient-heat transfer analysis for predicting thermal distributions, and thermomechanical analysis for structural behaviors. For concretes, transient heat formulations are written considering temperature dependent heat conduction and specific heat capacity and included within the thermomechanical analyses. Also, temperature dependent stress-strain behaviors including compression hardening and tension softening effects are implemented within the analyses. The proposed modeling technique for transient heat and thermomechanical analyses is first validated with experimental data of reinforced concrete (RC) beams subjected to high temperatures, and then applied to a bridge model. The bridge model is generated to simulate the fire incident occurred by a gas truck on April 29, 2007 in Oakland California, USA. From the simulation, not only temperature distributions and deformations of the bridge can be found, but critical locations and time frame where collapse occurs can be predicted. The analytical results from the simulation are qualitatively compared with the real incident and show good agreements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.47-52
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• 2008

In this paper partial discharge were simulated by conducted particle, a fine protrusion, surface discharge, which could be easy accumulated charge and concentrated electric field in the model GIS. In this times this paper measured and analyzed the radiated electromagnetic waves by using spectrum analyzer and antenna ($30{\sim}2,000[MHz]$ for measurement of EMI EMC in accordance with occurrence and propagation of partial discharge. In the basis of this results, a novel UHF(Ultra High Frequency) spherical sensor is presented. The measured impedance bandwidth of the proposed antenna is from 0.3[GHz] to 1.7[GHz]. Form results of this study, this antenna will be playing an important role for the sensor for insulation diagnosis system by UHF method of real site GIS and power equipment using $SF_6$ gas.