• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.487-495
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• 2015

This paper proposes a new robust decentralized power oscillation dampers (POD) design of doubly-fed induction generator (DFIG) wind turbine for damping of low frequency electromechanical oscillations in an interconnected power system. The POD structure is based on the practical $2^{nd}$-order lead/lag compensator with single input. Without exact mathematical model, the inverse output multiplicative perturbation is applied to represent system uncertainties such as system parameters variation, various loading conditions etc. The parameters optimization of decentralized PODs is carried out so that the stabilizing performance and robust stability margin against system uncertainties are guaranteed. The improved firefly algorithm is applied to tune the optimal POD parameters automatically. Simulation study in two-area four-machine interconnected system shows that the proposed robust POD is much superior to the conventional POD in terms of stabilizing effect and robustness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.33-34
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• 2006

The most bottleneck of development of automation excavator system is the making mathematical linear model. Because of non-linear of control circuit, cylinder, join in hydraulic circuit, and heavy loading so on. Therefore, whatever robust controller is designed, real experimentation is necessary. But, a real experimentation has many risks. The excavator is expensive and large size. Therefore a development of experimentation system is difficult and not safe. Specially, there have a difficulty, because of big noise. So, on experimentation is difficult in school. Manufacturing pneumatic excavator modeland using system identification, design a system transfer function in this paper. Also, planning m-PID Controller using CDM, and examining usefulness applied to actuality model.

• Journal of the Ergonomics Society of Korea
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• v.16 no.1
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• pp.97-105
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• 1997

An aircraft simulator for ergonomics testing and pilot training was developed from the joint work Agency for Defense Development(ADD) and Daewoo Heavy Industry, LTD, in Korea at first time. It is basically to satisfy the requirements established by FAA-AC-120-40C ( 1995-JAN-26). The aircraft simulator will be used mainly for ergonomics testing and pilot training for basic trainer on ADD and Korea Air Force in near futrue. This simulator reproduces faithfully the cockpit and flight characteristics of the KTX-1 aircraft. It is one of the latest full flight simulators that have the CGI(computer graphic image) visual system and six degree of freedom motions system. Development efforts focused on user-oriented design approach for ergonomics testing and flight training of pilots. Main characteristics of each subsystem are described such as cockpit, instruments, control loading system, motion system, visual system, aural system, instructor operation station and aircraft simulation softwear.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1225-1227
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• 1992

This paper presents a study on the variable structure PI(proportional and integrate) control which is insensible to the variation of parameters or external disturbance for driving DC motor. In the presented variable structure PI control (VSPIC), the sliding mode control was used at the below of 4000 rpm and PI control also used at the above of 4000 rpm with no load. In other way, the PI control was used at the below of 4000 rpm and the sliding mode control at the above of 4000 rpm with some loading, and then the output waveform following the variation of load was measured. intel 8031 microcomputer unit and IBM PC was combined to form the full system and the speed control was performed with it. The experimental result of the fast response to speed was more improve than it was open loop state. For load varing, the sliding mode insensible to external disturbance was applied and the improved response was obtained.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.57-67
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• 2008

Two test methods, nonrepetitive plate loading test (NPLT) and repetitive plate loading test (RPLT) are being used to control the quality of compaction through the evaluation of the stiffness of subgrade soils in the Korea railway industry. Subgrade reaction modulus ($k_{30}$) from the NPLT and strain modulus ($E_v$) from the RPLT are the index values to check them. The methods have similar aspects, but they differ in the modulus evaluation method, the numbers of loading stage, termination procedures, etc. This paper analyses the differences of the two test methods and evaluates the relationship between subgrade reaction modulus and strain modulus. In order to develop the relationship, total 22 tests were performed including the NPLT and the RPLT at the 6 original grounds, and 5 upper or lower subgrades in Kyungbu High Speed Railway II stage construction sites. According to the soil conditions, the relationship between subgrade reaction modulus and strain modulus was proposed with corrections by considering strain states, mean confining pressures, and Poisson's ratio.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.259-262
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• 1996

This paper proposes an approach in modeling a 4x60inch Allis Chalmers Hydrocone Crusher [1] hydroset and presents some numerical simulation results. The mining and quarry industry is one of the industries which extensively use hydrocone crushers, which are a family of cone crushers, for rock size reduction. Field studies have proved that if proper control and management of these machines is undertaken, they can yield an increased production output of more than 30%, in addition substantial savings in both energy consumption per unit ton produced and manpower can be easily realized. In order to achieve these economic benefits, high performance from these machines is expected. Implementing automatic control for such machines would be a great leap towards achieving both economic benefits and more effective fool-proof predictive maintenance. But, unfortunately, for such a control system to be designed, it necessary to make a mechatronical model of this plant. The plant model is able to give us an insight into variations of both the plant gap setting (displacement) and system pressure due to variable loading arising from the crushing process.

• Journal of Environmental Health Sciences
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• v.34 no.6
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• pp.423-432
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• 2008

In this study, we investigated the possibility of auto control and the proper operating factors in the BNR(Biological Nutrient Removal) process using an NADH(Reduced Nicotinamide Adenine Dinucleotide) fluorometer, which characterized the emitted fluorescence when activated by flashes of UV light at 460 nm. In terms of finding adequate operating parameters, results indicted that nitrification efficiency decreased in the controlled DO while denitrification efficiency decreased in the controlled pH. The above results indicated that controlled operating condition after combination with NADH, DO and pH was resonable. Result obtained from the correlation between NADH and pH showed that variation trend of influent loading was similar to those of NADH and pH, and also the variation cycle was repeated on a daily basis. Consequently, this result showed the increase of BOD loading caused the nitrification efficiency to decrease because air-flow, required for nitrification, was reduced, and so the NADH value was increased. From these results, it is possible to use NADH flourimetry to assess the variation of organic load and nitrification efficiency in the case of small change in influent pH such as in sewage and also to handle and operate the load variation in the auto control system using the NADH fluorometer.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.107-112
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• 1997

In this study of made Autmation system is moving linear transfer system for mainly forming of small electronic unit and other at press line. This system for loading and unloading a workpiece has been installed in a press in order to load and unload a workpiece from a press die. Main Control method be used PLC. It took data of input from each sensor and send signal of output to actuator by sequence program also, we try to Characteristics test of this system has good condition when operating with raser measurmant.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.93-100
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• 2004

In this study, a support system is developed for the design of facility structures. This system is called Expert System for Design Optimization of Industrial Plant Structures (EDIPS). Based on the strength assessment of steel-plate structures such as ships and off-shore structures, a detailed load calculation method is developed utilizing the database of various plant structures. The method, developed in support of design and for the assessment of strength, constitutes a part of EDIPS. By providing relevant and consistent design data and procedures to engineers, EDIPS is expected to be useful as an important development tool for maritime distribution system that is used to control the transportation by ships and loading unloading, and storage of cargo.

• Structural Engineering and Mechanics
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• v.31 no.5
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• pp.567-585
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• 2009

The aim of this study was to investigate the flexural behavior of reinforced concrete beams strengthened with a novel strengthening system. Concrete beams were strengthened with a hybrid retrofit system consisting of high strength steel cords impregnated in an inorganic fireproof matrix (Geopolymer). The strengthened reinforced concrete beams along with non-strengthened control beams were tested monotonically under four point bending loading conditions. Moreover, an analytical model is introduced, that can be used to analyze the flexural performance of the strengthened beams. The experimental results indicate that the failure of the strengthened beams was based on the yielding of the reinforcement in the tension face of the beams, followed by a local slippage of the steel cords. The flexural stiffness of the strengthened beams was significantly improved compared to the stiffness of the non-strengthened beams. In conclusion, the strengthening system can provide an effective alternative to commercially available systems.