• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.78-86
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• 2000

This study identified a linear time-invariant mathematical model of each stand of a five-stand tandem cold mill. Two model identification methods are applied to construct a linear model of each stand of the tandem cold mill. For the model identification the input-output data that have interstand interference property in tandem cold rolling are obtained from a nonlinear simulator of the tandem cold mill. And a linear model of each stand is identified with N4SD(numerical algorithms for subspace state space system identification) method based on a state-space model and Least Square algorithm based on a transfer function. Furthermore a modeling error of the tandem cold mill is quantitatively analyzed from a maximum singular value plot of error function between an identified nominal model and uncertain model. In conclusion the comparison of the output signals between the existing Taylor linearized model the identified linear model and the nonlinear model of the tandem cold mill shows the accuracy and the applicability of the proposed identified model.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.67-76
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• 2006

In this paper the moment transfer efficiency of a web and the strain concentration at the RHS (Rectangular Hollow Section) column-to-steel beam connections was evaluated. Initially, non-linear finite element analysis of five bare steel beam models was conducted. The models were designed to have different detail at their beam-to-column connection, so that the flexural moment capacity was different respectively. Analysis results showed that the moment transfer efficiency of the analytical model with RHS-column was poor when comparing to model with WF(Wide Flnage)-column due to out-of-plane deformation of the RHS-column flange. The presence of scallop and thin plate of RHS column was also a reason of the decrease of moment transfer efficiency, which would result in a potential fracture of the steel beam-to-column connections. Analytical results were compared with the previous experimental results. The analytical and the previous experimental results showed that the strain concentration was inversely proportional to the moment transfer efficiency of a beam web and the deformation capacity of connection was poor as their moment transfer efficiency degrades. Further finite element analyses of composite beam with a floor slab revealed that the neutral axis moved toward the top flange and the moment transfer efficiency of a beam web decreased, which led to premature failure of the connection.

• Journal of Power Electronics
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• v.17 no.2
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• pp.533-541
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• 2017

This paper presents a novel Parameter-Independent Fictive-Axis (PIFA) approach for the Voltage-Oriented Control (VOC) algorithm used in grid-tied single-phase inverters. VOC is based on the transformation of the single-phase grid current into the synchronous reference frame. As a result, an orthogonal current signal is needed. Traditionally, this signal has been obtained from fixed time delays, digital filters or a Hilbert transformation. Nevertheless, these solutions present stability and transient drawbacks. Recently, the Fictive Axis Emulation (FAE) VOC has emerged as an alternative for the generation of the quadrature current signal. FAE requires detailed information of the grid current filter along with its transfer function for signal creation. When the transfer function is not accurate, the direct and quadrature current components present steady-state oscillations as the fictive two-phase system becomes unbalanced. Moreover, the digital implementation of the transfer function imposes an additional computing burden on the VOC. The PIFA VOC presented in this paper, takes advantage of the reference current to create the required orthogonal current, which effectively eliminates the need for the filter transfer function. Moreover, the fictive signal amplitude and phase do not change with a frequency drift, which results in an increased reliability. This yields a fast, linear and stable system that can be installed without fine tuning. To demonstrate the good performance of the PIFA VOC, simulation and experimental results are presented.

• 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.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.287-291
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• 2018

The CNTFET, which is attracting attention as a next-generation semiconductor device, can obtain ballistic or near-ballistic transport at a lower voltage than that of conventional MOSFETs by depositing CNTs between the source and drain of the device. In order to increase the performance of the CNTFET, a large number of CNTs must be deposited at a high density in the CNTFET. Thus, various manufacturing processes to increase the density of the CNTs have been developed. Recently, the Directional Shrinking Transfer Method was developed and showed that the current density of the CNTFET device could be increased up to 150 uA/um. So, this method enhances the possibility of implementing a CNTFET-based integrated circuit. In this paper, we will discuss how to evaluate the performance of the CNTFET device compared to a MOSFET at the circuit level when the CNTFET is fabricated by the Directional Shrinkage Transfer Method.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.7
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• pp.952-956
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• 2011

The objective of the study was to evaluate the effect of passive transfer status, determined by measuring serum immunoglobulin (Ig) concentration 24 hours after parturition, on growth performance in buffalo calves allowed to nurse the dam during the first month of life. Serum Ig concentration 24 hours after birth ranged from 28.1 to 35.9 mg/ml, birth weight ranged from 29 to 41 kg, body weight 30 days after birth ranged from 48.5 to 62.9 kg. The Average Daily Gain (ADG) from birth to day 30 ranged from 448 to 1,089 g/d. Significant linear associations were detected between serum Ig concentration 24 hours after birth and day-30 weight (p< 0.05; $R^2$ = 0.31) and between serum Ig concentration 24 hours after birth and ADG from birth to day 30 (p<0.001; $R^2$ = 0.72). Results indicated that passive transfer status was a significant source of variation in growth performance when buffalo calves nursed the dam. Maximizing passive transfer of immunity by allowing calves to nurse the dam can increase growth performance during the first month of life.

• Journal of the korean society of oceanography
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• v.38 no.3
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• pp.135-142
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• 2003

Gas flux across the air-sea interface is often determined by the product of gas transfer velocity k) and the difference of concentrations in water and air. k is primarily controlled by wind stress on the air-sea interface, thus all parameterizations ofk involve wind speed, a rough indicator of wind stress, as one of the independent variables. We attempted to explore the spatial and temporal variations of k in the East (Japan) Sea using a database from Naet al. (1992). Three different parameterizations were employed: those of Liss and Merlivat (1986), Wanninkhof(1992), and Wanninkhofand McGillis (1999). The strong non-linear dependence of k on wind speed in all parameterizations leads us to examine the effect of time resolution, in which the binned wind speeds are averaged, on the estimation ofk. Two time resolutions of 12 hours (short-term) and one month (long-term) were chosen. The mean wind speeds were fed into the given parameterizations, resulting in six different transfer velocities of $CO_2$ ranging from 12 to 32 cm/h. In addition to the threefold difference depending on the choice of parameterization, the long-term average of wind speed results in a value ofk up to 20% higher than the short-term (12 hours) average of wind speed due to the non-Rayleigh wind distribution in the East (Japan) Sea. While it is not known which parameterization is more reliable, this study proposes that the time-averaged wind speed should not be used in areas where non-Ralyleigh wind distribution prevails such as the East (Japan) Sea. The net annual $CO_2$ flux was estimated using the value of k described above and the monthly ${\Delta}fCO_2$ of Oh et al. (1999); this ranges from 0.034 to 0.11 Gt-C/yr.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.259-266
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• 1979

Linear polyethers were prepared by the reaction of diphenoxide anions from 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxylphenyl) sulfide, and bis (khydroxyphenyl) sulfone with 1,6-dibromohexane in aqueous/nitrobenzene heterogeneous phases. Tetrabutylammonium bromide was employed as a phase transfer catalyst. The polymerizations were dependent both on stirring speed and catalyst level, but only up to certain maximum values. Distribution studies demonstrated transference of diphenoxide anions from aqueous phase into nitrobenzene in the presence of the catalyst. Some of polymers were characterized with respect to their intrinsic viscosities (0.09-O.16), number average molecular weight (2400-4800)) and thermal properties. The use of a new terminology, 'phase transfer polymerization?, is proposed to differentiate this type of polymerizations from interfacial polycondensations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.4
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• pp.39-52
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• 2023

In this study, project information of government-funded research institute in the food field was collected and analyzed to systematically identify the factors affecting the process of transferring technological achievements of public research institute to the private sector. This study hypothesized that human resources, financial resources, and technological characteristics as input factors of R&D projects affect output factors, such as research papers or patents produced by R&D projects. Moreover, these outputs would serve as drivers of the technology transfer as one of the R&D outcomes. Linear Regression Analysis and Poisson Regression Analysis were conducted to empirically and sequentially investigate the relationship between input factors and output and outcome of R&D projects and the results are as follows: First, the principle investigator's career and participating researcher's size as human resource factors have an influence on both the number of SCI (science citation index) papers and patent registration. Second, the research duration and research expenses for the current year have an influence on the number of SCI papers and patent registrations, which are the main outputs of R&D projects. Third, the technology life cycle affects the number of SCI papers and patent registrations. Lastly, the higher the number of SCI papers and patent registrations, the more it affected the number of technology transfers and the amount of technology transfer contract.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.323-328
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• 2004

According as the quantity of goods transported by ship is increasing about $7\%$ per year, a port environment is rapidly changing. To meet this situation successfully, the development of the next generation port loading and unloading system (LMTT) is studied. A Frame of shuttle car for LMTT(Linear Motor-based Transfer Technology) consist of three parts which are outer beam inner beam and cross boom. Outer boom supports a container and inner boom is a framework and cross boom reinforces outer and inner boom. In this study, we carried out the finite element analysis for the effect of cross boom on the strength and stiffness qf the frame according to the number if cross beam leading position of container, the distance ratio if inner boom from center.