• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.306-312
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• 2013

Doubly fed induction generator (DFIG) systems widely used globally are highly sensitive to the grid disturbance due to the structure that the stator is connected to the grid. In the past, when a grid fault occurs in order to prevent a system, generators are separated from the grid regardless of the fault duration time. Recently, however, the grid connection standards(Grid Code)says that for the failures removed within a certain time, the generator remains operation without separating from the grid. This paper proposes a new flux tracking LVRT(Low-Voltage Ride Through) control based on system modeling equations. The validity of the proposed strategy has been demonstrated by computer simulations.

• Food Science and Preservation
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• v.5 no.2
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• pp.127-132
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• 1998

In order to fad out an efficient way of topdressing nitrogen fertilizer in mulch-cropping system of onion(Allium cepa L.), solid, slow-release, and liquid forms of nitrogen fertilizers were allied to cv. 'Changnyungdaego' various number of times at different time, with 5 topdress applications of solid fertilizer serving as a control. Whole basal application of conventional solid fertilizer and 2 slow-release fertilizers were labor-saving and showed improved storage quality of bulbs, but resulted in poor plant growth and considerably low yield due to fertilizer shortage from early April. This suggests that topdress application is necessary. Liquid form of nitrogen fertilizer was more effective for plant growth and yield and saving labor than the solid form. Early applications was effective for increasing yield and storage quality of onion bulbs harvested. Thus two applications of liquid form of nitrogen fertilizer in February and March at rome month interval are recommended in mulch crowing system of onion.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.33-38
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• 2004

Molecular modeling of gas permeation through zeolite membranes with/without intercrystalline region was carried out. Molecular dynamics (MD) and Monte Carlo (MC) simulations were performed to estimate the diffusion coefficient and adsorption parameters respectively, and our proposed combined method of molecular simulation techniques with a permeation theory (CMP) was used to estimate gas permeability. The calculated permeability of gases (Ar, He, Ne, $N_2$, $0_2$, $CH_4$) at 301 K for the single crystal membrane model was about one order of magnitude larger than the experiential values, although the dependence on the molecular weight of the permeating species agreed with experiments. On the other hand, the estimated permeability using the diffusivity and adsorption parameters of the intercrystalline region model was in good agreement with the experiments. The consistency between experiments and the estimated values means the importance of considering the intercrystalline region and the validity of CMP method to predict the performance of zeolite membranes.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.768-770
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• 1996

This paper propose neural network which is one of self-organizing techniques. It is composed neural network controller as input signal is error and change of error which is optimal output, and is learned system by using a error back-propagation learning algorithm is one of error mimizing learning methods. In order to achieve practical real time control reduce on learning time, it is applied to load-frequency control of nonlinear power system with using a moment learning method. It is described in such a case considering constraints for a rate of increace generation-rate.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.38-40
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• 2003

This paper describes the integrated dynamic stability(IDS) program for tuning the power system controllers, such as PSS, AVR and so on. IDS consists of three modules; power flow module, PWRLF, to calculate large scale power system load flow solutions, IDS/PSS module to calculate eigenvalues and frequency response in the range of frequency from 0.2Hz to 2Hz, and IDS/NEA module to calculate eigenvalues in the range of frequency from 5.0Hz to 55Hz. In addition, IDS provides graphic user interface(GUI) in order to let the user handle and analyze the input data and the results of calculation with convenience.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.214-217
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• 1993

This paper presents a new identification method which utilizes fuzzy inference in parameter identification. The proposed system has an additional control loop where a real plant is replaced by a plant model. The control system to be designed is to satisfy the following specifications: 1) It has zero steady-state error. 2) It has adequate damping characteristics. 3) 1),2) satisfied, it has a shortest rise-time. Fuzzy rules describe the relationship between comparison results of the features and magnitude of modification in the model parameter values. This method is effective in auto-tuning because the response of the closed loop is verified. The proposed method is tested in simulation for several plants with first- order lags and dead-times. The results show that the proposed method is effective in practical use.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.97-103
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• 2015

This paper introduces two on-going projects for DC high temperature superconducting (HTS) cable systems in South Korea. This study proposes the application of DC HTS cable systems to enhance power transfer limits of a grid-connected offshore wind farm. In order to develop the superconducting DC transmission system model based on HTS power cables, the maximum transfer limits from offshore wind farm are estimated and the system marginal price (SMP) calculated through a Two-Step Power Transfer (TSPT) model based on PV analysis and DC-optimal power flow. The proposed TSPT model will be applied to 2022 KEPCO systems with offshore wind farms.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.2
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• pp.47-56
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• 1991

The specifications needed for the mobile cranes are summarized as the following : 1) there may be not occured the oscillation of the cargo at unloading point. 2)the required time from departure point to destination point may be as short as possible. 3) there may be not a collapse of cargo caused by the oscillation in the course that the crago is mobilling. In this paper, the linear fractional transformation method is adopted as a method in order to improve the above mentioned problems. A design method of servo system is developed by modifying Davison's method for the case that the homogeneous differential equations of reference input and disturbance are different types. The real time control of a mobile crane system is implemented by 16bits microcomputer with A/D and D/A converters to illustrate the application of the adopted method. The experimental results for the three types of the design methods; linear fractional transformation method, servo system design method and optimal control method are shown for the comparison.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.222-233
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• 1987

A dynamic modeling procedure for developing a control model of the driving system of a heavy industrial vehicle is presented. The dynamic model is derived by applying generalized Lagrangian equations to each component of the system and imposing kinematic relations between components as constraints. In order to obtain the control model, a few assumptions are made for the simplification of the nonlinear and complicated model, which is justified by the comparison of the simulation results of the original full nonlinear model and the simplified control model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.176-183
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• 2009

The objective of this study is to prepare the plans for managing construction noise effectively and solving the popular enmity from construction noise reasonably. In order to carry out this purpose, it covers the efficient improvement plans for adjusting the construction noise regulation standard rationally and managing the automatic noise measuring system which shows the advantage for construction noise management and popular enmity solution due to construction noise. The three alternative plans of the construction noise regulation standard and the recommendation plan including the guideline for installing and managing the automatic noise measuring system are suggested consequently.