• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.11a
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• pp.230-248
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• 2003

In this work an integrated model for paper plants combining wet-end and dry section is developed and a model predictive control scheme based on the plant model is proposed. Closed-loop process identification method is employed to produce a state-space model. Thick stock, filler flow, machine speed and steam pressure are selected as Input variables and basis weight, ash content and moisture content are considered as output variables. The desired output trajectory is constructed in the form of 1st-order dynamics. Results of simulations for control of grade change operations are compared with plant operation data collected during the grade change operations under the same conditions as in simulations. From the comparison, we can see that the proposed model predictive control scheme reduces the grade change time and achieves stable steady-state.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.152-158
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• 2010

Generally, the AC electrified railway systems have the power quality problems that are induced from the harmonic currents and the reactive power. This paper presents a single-phase hybrid active filter adopting a SRF(synchronous-reference-frame) control for improving power quality in the AC electrified railway systems. The single-phase hybrid active filter can compensate the harmonic currents and the reactive power through the proposed SRF control algorithm. The proposed control algorithm can extract the third and fifth harmonics through the MSRF(multiple-synchronous-reference-frames) which is used to apply the three-phase systems. Therefore, the hybrid active filter can compensates only the high-frequency harmonic currents whereas the passive filter compensates the low-frequency harmonic currents. Also, the proposed SRF control algorithm can compensate the reactive power by the closed-loop control. The Validity and the effectiveness of the proposed SRF control method for the hybrid active filter are illustrated through the simulation results.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.7-14
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• 2001

In this work, the chemical composition of the exhaust gas from domestic gas boiler has been analysed in the point of thermodynamics and CO sensor has been characterized. We proposed that the combustion condition can be estimated by the exhaust gas composition, i.e., the excess air ratio and combustion temperature can be calculated simply by the measurement of the $O_{2}$ fraction and $H_{2}/CO$ in the exhaust gas. By analyse the on site situation domestic boiler, the excess air ratio is about $55\~110\%$. Therefore, the CO may be produced in domestic gas boiler by luminous(yellow) flames rapidly lose heat by radiation, turbulent flames may be partially quenched by the action of steep velocity gradients, and flames burning very close to a cold wall may be partial1y quenched by heat conductivity to the wall. The output voltage of CO sensor is lineally depend on the CO and $H_{2}$concentration. And the exhaust CO from boiler can be reduced by closed loop control with CO sensor

• IE interfaces
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• v.13 no.3
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• pp.378-387
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• 2000

As the globalization of manufacturing companies continues, the scope of dependence between these companies and distributors, and other suppliers are growing very rapidly since no one company manufactures or distributes the whole product by themselves. And, the need to increase the efficiency of the whole supply chain is increasing. This paper deals with a multi-plant lot-sizing problem(MPLSP) which happens in a decentralized manufacturing system of a supply chain. In this study, we assume that the whole supply chain is driven by a single source of independent demand and many levels of dependent demands among manufacturing systems in the supply chain. We consider setup cost, transportation cost and time, and inventory holding cost as a decision factor in the MPLSP. The MPLSP is decomposed into two sub-problems: a planning problem of the whole supply chain and a lot-sizing problem of each manufacturing system. The supply chain planning problem becomes a pure linear programming problem and a Generalized Goal Decomposition method is used to solve the problem. Its result is used as a goal of the lot-sizing problem. The lot-sizing problem is solved using the CPLEX package, and then the coefficients of the planning problem are updated reflecting the lot-sizing solution. This procedure is repeated until termination criteria are met. The whole solution process is similar to Lagrangian relaxation method in the sense that the solutions are approaching the optimum in a recursive manner. Through experiments, the proposed closed-loop hierarchical planning and traditional hierarchical planning are compared to optimal solution, and it is shown that the proposed method is a very viable alternative for solving production planning problems of decentralized manufacturing systems and in other areas.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.132-137
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• 2003

This performance is motivated to develop a tracking antenna system for receive the satellite broadcasting signal in the coast sailing ship. Therefore, this system is made to small size, light weight and simple operation which is must to low cost system for popularization of small size ship and adaptive possibilities with useful on a ship in the coast using 1 axis Az-mount. The antenna mount structure is a compact size and easy operation to the Az-axis type which is operated by step motor. The antenna unit is a domestic made plate type of patch array and ship's moving detection is using the gyro sensor for ship's moving control. We are designed to algorithm, which walking is abreast for step track and ship's moving compensation. Ship's moving compensation is adapted to the closed loop control method by detection from gyro sensor. This system is consisted of micro processor, ADC, comparative amplifier, step motor driver, mount mechanism and algorithm. We have analysised the tracking performance of prototype on sailing ship board.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.114-127
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• 2016

An increase of groundwater flux in BHE system creates that ground temperature (locT) becomes lower in summer and higher in winter time. In other words, it improves significantly the performance of BHE system. The size of thermal plume made up by advection driven-flow under the balanced energy load is relatively small in contrast to the unbalanced energy load where groundwater flow causes considerable change in the size of thermal plume as well ground temperature. The ground temperatures of the up gradient and down gradient BHEs under conduction only heat transport are same due to no groundwater flow. But a significant difference of the ground temperature is observed between the down gradient and up gradient BHE as a result of groundwater flow-driven thermal interference took placed in BHE field. As many BHEs are designed under the obscure assumption of negligible groundwater flow, failure to account for advection can cause inefficiencies in system design and operation. Therefore including groundwater flow in the design procedure is considered to be essential for thermal and economic sustain ability of the BHE system.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.163-171
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• 1998

Degradation of polymer additives is enhanced at higher temperature of the test solutions. The degradation of Co-polymer solution was investigated experimentally in a closed loop at the temperature of 6$0^{\circ}C$ and 8$0^{\circ}C$ with various polymer concentrations of 100, 200, 400, 600 ppm in order to see the effect of temperature and polymer concentration with time. The degradation effect were found to be more dependent on temperature than mechanical shear. The friction factor versus Reynolds number curves show that in the range of Reynolds number number 50,000~150,000 the friction was decreased as Reynolds number increased and the friction of solution at low temperature approached to Virk's maximum drag reduction asymptote. For constant flowrates and temperatures the degradation effect was found to be less likely in higher polymer concentration. For constant flowrates and polymer concentrations the degradation rates are affected mainly by temperature. At the temperature of 8$0^{\circ}C$ and polymer concentration of 100 ppm, drag reduction effect was disappeared after 4 hours. However, this thermal degradation could be avoided with additional materials such as surfactants which are supposed to enhance the bonding forces between polymer molecules.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.57-66
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• 2009

The conventional fixed gain PI controller is very sensitive to step change of command speed, parameter variation and load disturbances. The precise speed control of interior permanent magnet synchronous motor(IPMSM) drive becomes a complex issue due to nonlinear coupling among its winding currents and the rotor speed as well as the nonlinear electromagnetic developed torque. Therefore, there exists a need to tune the PI controller parameters on-line to ensure optimum drive performance over a wide range of operating conditions. This paper proposes hybrid intelligent-PI(HIPI) controller of IPMSM drive using adaptive learning mechanism(ALM) and fuzzy neural network(FNN). The proposed controller is developed to ensure accurate speed control of IPMSM drive under system disturbances and estimation of speed using artificial neural network(ANN) controller. The PI controller parameters are optimized by ALM-FNN at all possible operating condition in a closed loop vector control scheme, The validity of the proposed controller is verified by results at different dynamic operating conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.1-11
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• 2011

The skid-steering method that applied a number of mobile robot currently is extremely effective in narrow area. But it contains several problems such as its natural properties, slip, occurred by different direction between vehicle's driving and wheel's rotary. Through this paper, suitable control algorithm of $6{\times}6$ skid steering wheeled vehicle and its driving methods are proposed by analyzing the behavior $6{\times}6$ skid-steered wheeled vehicle model designed by engineering analysis strategy. To do this, based on a behavior of designed driving system, required torque and other performance of in-wheel type motor system are considered, and finally control algorithm for each wheel is proposed and simulated using this model. To test the proposed vehicle system, driver model is designed using PID closed loop system and included in the total driving control algorithm. The Performance of designed vehicle model is verified by using DYC (Direct Yaw Control) cornering mode and slip mode control to follow the steering input which are essential to evaluate the driving performance of $6{\times}6$ vehicle. Proposed modeling strategy and control method will be implemented to the real $6{\times}6$ in-wheel drive type vehicle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.103-109
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• 2010

In this paper, breakdown characteristics of soil in a coaxial cylindrical electrode system stressed by impulse currents were experimentally investigated. The breakdown voltage and current waveforms for 4 types of soils were measured, and the threshold electric field intensity, the time-lag to breakdown and the voltage-current (V-I) curves were analyzed and discussed. As a result, the breakdown voltage and current waveforms are strongly dependent on the grain size of soil, and the voltage and current waveforms for gravel and sand differ from those for silt and loess. The threshold electric field intensity Ec is increased in the order of gravel, sand, loess and silt. The V-I curves for all test samples show a 'cross-closed loop' of ${\infty}$-shape. Also, the time-lag to breakdown for gravel and sand are longer than those for silt and loess. It is expected that the results presented in this paper will provide useful information on the design of improving transient performance of a grounding electrode system subjected to lightning current considering the soil ionization.