• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.5
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• pp.233-241
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• 2000

This paper presents a systematic design procedure of $H_{\infty}$ controller of TCSC for damping low frequency inter-area oscillations in large power systems. Sensitivities of the inter-area mode for changes in line susceptance are computed using the eigen-sensitivity theory of augmented system matrix and TCSC locations are selected using the line sensitivities. The reduced model required for designing a manageable-size $H_{\infty}$ controller is obtained using the reduced frequency domain system identification method and the various weighting functions are tuned systematically to provide a robust performance. The proposed $H_{\infty}$ controller proved to be very effective for damping the inter-area mode of the large KEPCO power system.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.194-201
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• 2006

Roof-fairing and deflector system have been used on heavy-duty trucks to minimize aerodynamic drag force not only for driving stability of the truck but also for energy saving by reducing the required driving power of the vehicle. In this study, a numerical simulation was carried out to see aerodynamic effect of the drag reducing device on the model vehicle. Drag and lift force generated on the five different models of the drag reducing system were calculated and compared them each other to see which type of device is efficient on the reduction of driving power of the vehicles quantitatively. An experiment has been done to see airflow characteristics on the model vehicles. Airflow patterns around the model vehicles were visualized by smoke generation method to compare the complexity of airflow around drag reducing device. From the results, the deflector systems(Model 5,6) were revealed as a better device for reduction of aerodynamic drag than the roof-fairing systems(Model 2,3,4) on the heavy-duty truck and it can be expected that over 10% of brake power of an engine can be saved on a tractor-trailer by the aerodynamic drag reducing device at normal speed range($80km/h{\sim}$).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.447-453
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• 2007

In the multipath fading channel, OFDM(Orthogonal Frequency Division Multiplexing)system possess the characteristics of ISI/ICIwith prefix, but a weak point of circuit complexity and PAPR problem. SC-FDE(Single Carrier with Frequency Domain Equalization) performance is similar to OFDM system, but equalizer is complex in frequency domain. In this paper, simple proportional equalizer offer for SC-FDE system, it useful method in the $2GHz{\sim}\;10GHz$ channel model such as indoor, outdoor, SUI. It prove using MATLAB simulation, speed faster then OFDM system, reduce terminal complexity in same test condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.1
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• pp.70-79
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• 2015

In this paper, enhanced stand-alone operation and development of Matlab/Simulink model of emergency diesel based hybrid energy system is presented. Simulations based on the remote community or islands were performed for PV-diesel-battery hybrid system. Modeling of PV-diesel-battery integrated system is done to perform under the solar radiation and load conditions on Matlab/Simulink platform. The models of diesel generator unit, battery energy storage system, PV and frequency-power control are developed and simulation studies have been carried out under various conditions using Matlab/Simulink and SimPowerSystem. It is demonstrated that the proposed system can provide reliable and good quality power to the customers in diesel synchronous generator-based hybrid energy systems.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.417-420
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• 2006

This paper suggests that resource allocation algorithm in multiuser orthogonal frequncy divisioin multiplexing (OFDM). The proposed algorithm considers throughput maximization with power constraint and quality of service (QoS) constraint. This problem has a optimal solution with using well known water-filling algorithm but the algorithm requires high computational complexity. Therefore the problem needs a sub-optimal algorithm for decreasing computational complexity. We propose a sub-optimal joint subcarrier and power allocation algorithm for multiuser OFDM system and compare with previous resource allocation algorithm.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1855-1860
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• 2010

Electric vehicles have reached a new level of development with introductions by Chrysler, Ford, Honda and Toyota. Today's charging technology includes conductive and inductive charging systems. There are three standardized charging levels: Level 1: charging can be done from a standard, grounded AC 120V, 3-prong outlet available in all homes; Level 2: charging is at AC 240V, 40 amp charging station with special consumer features to make it easy and convenient to plug in and charge EVs at home or at an EV charging station; Level 3: a high-powered charging "fast charge" technology currently under development that will provide a charge in less than 15 minutes. The incoming AC power is converted to DC and stored in the vehicle's batteries. In this paper, we investigated the application of urban railway DC electric power for electric car charging system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.320-321
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• 2008

In this paper, new simulator based on EMTP was introduced for simulation of underground power cable system. The newly developed simulator was named as Power Cable Simulator(PCS), and it can simulate the various normal conditions including sheath circulating current. It is also easier to use than conventional software, such as EMTP and CabSim, because all the data for calculating the cable parameters are stored in a database(DB) within a PCS. In addition, the accuracy of PCS is also proved through the comparison between the calculation and simulation of sheath current.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2152-2154
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• 1999

In this paper, we suggested the design rule of high-voltage rectangular waveform generator working in low frequency domain (5Hz $\sim$ 60Hz). Most of the commonly used power electronic switching devices have voltage ratings up to several kV. So it is difficult to design and fabricate high-voltage switching systems with the power electronic devices alone. We have combined IGBTC(1200V, 50A) with the specially designed transformer to get the high-voltage rectangular waveforms up to 40kV. In this work. next two things are the main factors. The first one is design of transformer working low-frequency domain close to 5Hz. And the second one is additional voltage source to floating the transformer voltage output. As a result, we can get frequency-variable and high-voltage rectangular voltage waveform and this can be a more efficient power source of sandpaper manufacturing process.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.27-33
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• 2011

HCPV(High Concentrated PV) systems have well known for CPV market all over the world. Low concentration type silicon based modules have been introduced in the market. But low cost of standard flat silicon modules made them useless nowadays. High cost of compound semiconductor solar cell reduced cost effective cpv module production than that of recently silicon solar cell. In order to overcome increasing cost of CPV module, we study middle concentration type fresnel lens simulation using concentrated type silicon based solar cell. Linear type fresnel lens made production of CPV module without secondary optics such as light pipe or light tunnel. This type of fresnel lens design makes more cost effective solution for cpv niche market.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.9
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• pp.766-772
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• 2016

Recent advances in networking and computers, especially internet of things (IoT) technologies, have improved the quality of home life and industrial sites. However, the security vulnerability of IoT technologies causes life-threatening issues and information leakage concerns. Studies regarding security algorithms are being conducted. In this paper, we proposed SEED algorithms based on one time passwords (OTPs). The specified server sent time data to the client every 10 seconds. The client changed the security key using time data and generated a ciphertext by combining the changed security key and the matrix. We applied the SEED algorithms with enhanced security to Linux-based embedded boards and android smart phones, then conducted a door lock control experiment (door lock & unlock). In this process, the power consumed for decryption was measured. The power consumption of the OTP-based algorithm was measured as 0.405-0.465W. The OTP-based algorithm didn't show any difference from the existing SEED algorithms, but showed a better performance than the existing algorithms.