• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.3
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• pp.1-9
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• 2001

Impact tests are performed on the high strength structural steel that is being developed for the submarine material. Especially, the impact characteristics of this structural steels at low temperatures are investigated by charpy impact testing. Hyperbolic tangent curve fitting method is used to evaluate the LSE(lower shelf energy), USE(upper shelf energy) and DBTT(ductile-brittle transition temperature). Proportional equations between charpy impact energy and lateral expansion are obtained using the test results. Effect of temperature on the fracture appearance is investigated by using SEM.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.7
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• pp.552-559
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• 2002

The fault detection and diagnosis (FDD) technology may be applied in order to decrease the energy consumption and the maintenance cost of the air conditioning system. In this study, rule bases and curve fitting models were used to detect faults in an air handling unit. Gradually progressed faults, such as the fan speed degradation, the coil water leakage, the humidifier nozzle clogging, the sensor degradation and the damper stoppage, were applied to the developed FBD system. Simulation results show good detections and diagnoses of these faults. Therefore, this method may be effectively used for the fault detection and diagnosis of the air handling unit.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1995.10b
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• pp.15-24
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• 1995

This paper describes a system that can be used to recognize an unknown material regardless of the fuzzy neural network(FNN). There are some problems to realize the recognition system using temperature response. It requires too many memories to store the vast temperature response data and it has to be filtered to remove noise which occurs in experiment. And the temperature response is influenced by the change of ambient temperature. So, this paper proposes a practical method using curve fitting to remove above problems of memories and noise. and FNN is proposed to overcome the problem caused by the change of ambient temperature. Using the FNN which is learned by temperature responses on fixed ambient. Temperatures and known thermal conductivity, the thermal conductivity of the material can be inferred on various ambient temperatures. So the material can be recognized by the thermal conductivity.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.11
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• pp.783-789
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• 1987

It is anticipated that the accuracy of the numerical value obtained by curve fitting is mainly governed by how to evaluate the term of exponential integral involved in the theory of TSC, so that evaluation process of the instegral term concerned is replaced by Romberg numerical integral method instead of the conventional approximation method of asymtotic expansion or Simmons-Tayler with expectation to get the improved accuracy. In order to examine the effectiveness of the proposed method, the new algorithm is tried to adapt to the peak of TSC observed about 356 K im the specimen of polyethylene terephthalate in which carrier is injected by means of corona dischargel. As theresults, it is confirmed that the proposed method being cooperated with Romberg numerical intergral intergral is superior to the existing conventional curve fitting method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.34-40
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• 2012

Flux linkage of phase windings or phase inductance is an important parameter in determining the behavior of a switched reluctance motor (SRM) [1-8]. Therefore, the accurate prediction of inductance at aligned and unaligned rotor positions makes a significant contribution to the design of an SRM and its analytical approach is not straightforward due to nonlinear flux distribution. Although several different approaches using a finite element analysis (FEA) or curve-fitting tool have been employed to compute phase inductance [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase inductance at aligned and unaligned rotor positions is estimated by means of numerical method and magnetic equivalent circuit as well, and the proposed approach is analytically verified in terms of the accuracy of estimated inductance compared to inductance computed by an FEA simulation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.3
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• pp.215-218
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• 1990

Saturation growth model was evaluated to predict the formation of product as a function of time. Good agreement was observed with homogenous and heterogenous reactions, Prediction of product yield can be made reasonably using this model. In addition accuracy of measured values can be roughly evaluated by this model. User-friendly computer program in BASIC was written to evaluate the constants Pmax and K as well as averages of relative errors.

• Journal of Ocean Engineering and Technology
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• v.22 no.1
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• pp.70-74
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• 2008

It is important to reduce the vibration and noise of submarines and ships. For the purpose of noise reduction, various researches are actively being conducted on the employment of complex structures. However, in the case of numerical analysis for complex structures with damping materials, substantial errors can be generated by the absence of an exact damping model. Thus experimental model analysis is necessary for the verification of a numerical analysis for complex structures. In this research, vibration experiments are conducted in order to ascertain the vibration properties of cantilever beam attached damping materials. First, an initial value is obtained by using a direct linear method. Next, based on this initial value, the exact modal parameters of the cantilever beam are obtained by using the Newton-Raphson method.

• Journal of Magnetics
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• v.18 no.1
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• pp.57-64
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• 2013

Flux linkage of phase windings is a key parameter in determining the behavior of a switched reluctance motor (SRM) [1-8]. Therefore, the accurate prediction of flux linkage at aligned and unaligned rotor positions makes a significant contribution to the design of an SRM and its analytical approach is not straightforward due to nonlinear saturation in flux. Although several different approaches using a finite element analysis (FEA) or a curve-fitting tool have been employed to compute phase flux linkage [2-5], they are not suitable for a simple design procedure because the FEA necessitates a large amount of time in both modeling and solving with complexity for every motor design, and the curve-fitting requires the data of flux linkage from either an experimental test or an FEA simulation. In this paper, phase flux linkage at aligned and unaligned rotor positions is estimated by means of a reluctance network, and the proposed approach is analytically verified in terms of accuracy compared to FEA.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.77-83
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• 1997

This work is concerned with the algorithm of generating a new circular are interpolation. This research presents a new biarc curve fitting that is a circular interpolation method based on a triarc curve fitting. The triarc method, where a segment span is composed of three circular arcs, using maximum error estimation has the advantage of generating arc splines easily to a given tolerance. The new biarc method is called when the adjacent radii are the same in the same in the triarc method. In generating the machining data for various cam curves in CNC machining with the biarc method and the new biarc method, the latter accomp- lished faster NC-code generation, shorter NC-code block formation and machined the same cam profile more efficiently.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.223-231
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• 2022

Spectroscopies are the most widely used for understanding the crystallographic, chemical, and physical aspects of materials; therefore, numerous commercial and non-commercial software have been introduced to help researchers better handling their spectroscopic data. However, not many researchers, especially early-stage ones, have a proper background knowledge on the choice of fitting functions and a technique for actual fitting, although the essence of such data analysis is peak fitting. In this regard, we present a practical guide for peak fitting for data analysis. We start with a basic-level theoretical background why and how a certain protocol for peak fitting works, followed by a step-by-step visualized demonstration how an actual fitting is performed. We expect that this contribution is sure to help many active researchers in the discipline of materials science better handle their spectroscopic data.