• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
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• pp.1862-1863
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• 2006

In this paper, A new tuning method for IMC-PID controller is proposed with the identification using the relay method from closed-loop transfer function. It is considered a second-order plus delay time(SOPDT) model and selected a third-order plus delay time transfer function model as a target function. The filter function is derived from the suitable target function to satisfy the design specifications. A robustness test was done to verify the robust-stability.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 춘계학술대회 논문집
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• pp.29-36
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• 2004

A numerical study is carried out on the detonation wave propagation through a T-shaped flame tube, which represents a crucial part of the combustion wave ignition (CWI) system aimed for simultaneous ignition of multiple combustion chambers by delivering detonation waves. The formulation includes the Euler equations and an induction-parameter model. The reaction rate is treated based on a chemical kinetics database obtained from a detailed chemistry mechanism. A second-order implicit time integration and a third-order TVD algorithm are Implemented to solve the theoretical model numerically. A total of more than two-million grid points are used to provide direct insight into the dynamics of the detonation wave. Several important phenomena including detonation wave propagation, degeneration, and re-initiation are carefully examined. Information obtained can be effectively used to facilitate the design and optimization of the flame tubes of CWI systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.2879-2890
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• 2020

In this paper, we study the estimation of angle, range and polarization parameters of a bistatic polarization sensitive frequency diverse array multiple-input multiple-output (PSFDA-MIMO) radar system. The application of polarization sensitive array in receiver is explored. A signal model of bistatic PSFDA-MIMO radar system is established. In order to utilize the multi-dimensional structure of array signals, the matched filtering radar data can be represented by a third-order tensor model. A joint estimation of the direction-of-departure (DOD), direction-of-arrival (DOA), range and polarization parameters based on parallel factor (PARAFAC) algorithm is proposed. The proposed algorithm does not need to search spectral peaks and singular value decomposition, and can obtain automatic pairing estimation. The method was compared with the existing methods, and the results show that the performance of the method is better. Therefore, the accuracy of the parameter estimation is further improved.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• Asia pacific journal of information systems
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• 제15권4호
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• pp.109-133
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• 2005

The purpose of this study is to develop and validate a model of firm's IT capability based on IT resources such as IT infrastructure, IT personnel, and IT routine. To do this, the study defined IT capability as a third-order factor model and identified three conceptual dimensions of IT capability: IT infrastructure flexibility, IT personnel expertise, IT resource management capability, IT resource management capability indicates a capacity generated by IT routines, a new IT resource type identified in this study. The validity of the proposed model is evaluated with 243 firm level data using LISREL. The results of confirmatory factor analysis(CFA) demonstrated that the model is highly reliable and valid. Additionally, it was found that IT routines have a high potential as a new IT resource category.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.464-471
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• 2013

This paper proposes a hybrid searching algorithm based on parameter identification for power system load models. Hybrid searching was performed by the combination of particle swarm optimization (PSO) and a complex method, which enhances the convergence of solutions closer to minima and takes advantage of global searching with PSO. In this paper, the load model of interest is composed of a ZIP model and a third-order model for induction motors for stability analysis, and parameter sets are obtained that best-fit the output measurement data using the hybrid search. The origin of the hybrid method is to further apply the complex method as a local search for finding better solutions using the selected particles from the performed PSO procedure.

• 한국프랜차이즈경영연구
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• 제11권3호
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• pp.27-41
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• 2020

Purpose: This study was conducted for purpose to derive a model of the founding competency of undergraduate students preparing for job creation. We want to support undergraduate students who are preparing to start a job creation so that they can successfully start a job creation. In Korea, research on entrepreneurship competency has been actively conducted for a variety of subjects including undergraduate students, but research on job creation competency is insufficient. To this end, we intend to contribute to the success of undergraduate students preparing for job creation by deriving a job competency model. Research design, data, and methodology: In order to derive job creation competency, interviews were conducted with best practices in the job creation activity process, and the job creation competency was derived using Spencer and Spencer's competency model development process and competency dictionary. Result: The derived competencies were further supplemented through the verification of job creation experts and HRD experts, and a total of 3 competency groups, 13 competences, and 44 specific actions were derived. The derived job creation competency model is significant in that it is an initial study that attempts to develop job creation competency, that it can be a reference point for developing curriculum for undergraduate students preparing for job creation, and that they have developed a competency model in the new field of job creation. However, despite this significance, there are some limitations. First, the derived competency model did not perform validity verification using quantitative research. Second, the difference analysis between the excellent group and the average group was not conducted. Third, the level of behaviors could not be staged. Lastly, it was not possible to compare it with the competency of franchisor and job creation for undergraduate student competency. Therefore, it is necessary to upgrade the job creation competency model by conducting follow-up studies. The following is suggested as a follow-up study. First, verification of the validity of job creation competency, and second, a comparative study of excellent cases and average group. Third, a study on the level of action level of job creation competency. Lastly, it is a comparative study of job creation competency and the competency of franchise affiliates.

• 한국기계가공학회지
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• 제21권4호
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• pp.53-59
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• 2022

In this study, an enhanced first-order shear deformation theory is proposed to efficiently and accurately predict the thermo-mechanical-viscoelastic coupled behavior of laminated composite structures. To this end, transverse shearstress and displacement fields are independently assumed, and the strain-energy relationship between these fields issystematically established using the mixed variational theorem (MVT). In MVT, the transverse shear stress fields are obtained from the third-order zigzag model, whereas the displacement fields of the conventional first-order model are considered to amplify the benefits of numerical efficiency. Additionally, a transverse displacement field with a smooth parabolic distribution is introduced to accurately predict the thermal behavior of composite structures. Furthermore, the concept of Laplace transformation is newly employed to simplify the viscoelastic problem, similar to the linear-elastic problem. To demonstrate the performance of the proposed theory, the numerical results obtained herein were compared with those available in the literature.

• 전기의세계
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• 제30권12호
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• pp.822-831
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• 1981

Many different schemes of the adaptive observer and controller have been developed for both continuous and discrete systems. In this paper we have presented a new scheme of the reduced order adaptive observer for the single input discrete linear time invariant plant. The output equation of the plant, is transformed into the bilinear form in terms of system parameters and the states of the state variable filters. Using the plant output equation the discrete implicit adaptive observer based on the similar philosophy to Nuyan and Carroll is derived and the parameter adaptation algorithm is derived based on the exponentially weighted least square method. The adaptive model following control system is also constructed according to the proposed observer scheme. The proposed observer and controller are rather than simple structure and have a fast adaptive algorithm, so it may be expected that the scheme is suitable to the practical application of control system design. The effectiveness of the algorithm and structure is illustrated by the computer simulation of a third order system. The simulation results show that the convergence speed is proportinal to the increasing of weighting factor alpha, and that the full order and reduced order observer have similar convergence characteristics.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1551-1558
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• 2001

Recently, a number of underground pipelines have been drastically increased. The integrity of these buried pipelines, especially gas transmitting pipelines, is of importance due to an explosive characteristic of natural gas. The third party damage is known as one of the most critical factor which causes fatal accidents. For this reason, a number of systems detecting third party damage are under development. The major concern in the development of third party damage detection system is to transmit vibration signals out of accelerometer to signal conditioner and data acquisition system without any interference caused by noise. The objective of this paper is to develope a fiber optic accelerometer applicable to third party damage detection system. A fiber optic accelerometer was developed by use of combining principles of one degree of freedom vibration model and an extrinsic Fabry-Perot interferometer. The developed fiber optic accelerometer was designed to perform with a sensitivity of 0.06mVg, a frequency range of less than 6kHz and an amplitude range of -200g to 200g. The developed, accelerometer was compared with a piezoelectric accelerometer and calibrated. In order to verify the developed accelerometer, the field experiment was performed. From the field experiment, vibration signals and the location of impact were successfully detected. The developed accelerometer is expected to be used for the third party damage detection system which requires long distance transmission of signals.