• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.1
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• pp.21-26
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• 2017

Failure of high-voltage transmission line, which is responsible for large-scale power transmission, can be reason for system voltage instability. There are many methods to prevent voltage instability like adjustment of equipment, the generator voltage setting, and load shedding. Among them, the load shedding, have a problem of economic loss and cascading effect to power system. Therefore, the execution of load shedding, amount and timing is very important. Conventionally, the load shedding setting is decided by the preformed simulation. Now, it is possible to monitor the power system in real time by the appearance of PMU(Phasor Measurement Unit). By this reason, some of research is performed about decentralized load shedding. The characteristics of the load can impact to amount and timing of decentralized load shedding. Especially, it is necessary to consider the influence of the induction motor loads. This paper review recent topic about under voltage load shedding and compare with decentralized load shedding scheme with conventional load shedding scheme. And simulations show the effectiveness of proposed method in resolving the delayed voltage recovery in the Korean Power System.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.48-56
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• 2015

There is a wide variety of system and applications in the power system. However, they have compatibility issues because they use different data standard and communication method. With the introduction of the smart grid, power system has been grow and diversified. Therefore power system need to be compatible with each other and the interoperability between applications is increasingly important. Thus, the IEC established IEC61970 and CIM Standard data exchange model for interoperability and system integration. Server-Client system was constructed which using CIM HSDA(Part4), a standard communication model, presented in IEC 619710. Also, self-developed real-time voltage stability analysis application and contingency analysis application was used. CIM HSDA was used for data input and real-time analysis. Tolerance of result which is in the range of allowable derived by Perform real-time voltage stability and contingency analysis of Jeju power system, and then compare it's result with PSS/E result.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.1
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• pp.37-47
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• 2018

Dynamic simulation is critical for electrical ship studies as it obtains the necessary information to capture and characterize system performance over the range of system operations and dynamic events such as disturbances or contingencies. However, modeling and simulation of the interactive electrical and mechanical dynamics involves setting up and solving system equations in time-domain that is typically time consuming and computationally expensive. Accurate assessment of system dynamic behaviors of interest without excessive computational overhead has become a serious concern and challenge for practical application of electrical ship design, analysis, optimization and control. This paper aims to develop a systematic approach to classify the sophisticated dynamic phenomenon encountered in electrical ship modeling and simulation practices based on the design intention and the time scale of interest. Then a novel, comprehensive, coherent, and end-to-end mathematical modeling and simulation approach has been developed for the latest Medium Voltage Direct Current (MVDC) Shipboard Power System (SPS) with the objective to effectively and efficiently capture the system behavior for ship-wide system-level studies. The accuracy and computation efficiency of the proposed approach has been evaluated and validated within the time frame of interest in the cast studies. The significance and the potential application of the proposed modeling and simulation approach are also discussed.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.245-248
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• 2000

In this paper a novel method for voltage disturbance detection is presented. This is a instantaneous detection method using normalized error get in synchronous reference frame and also it is implemented in digital. Feedback noise the problem of digital implementation is removed by a digital filter of which the time delay is compensated through numerical analysis.

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.38-41
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• 2002

We have investigated current-voltage-luminance characteristics of organic light-emitting diodes based on TPD/Alq$_3$organics depending on the application of forward-backward bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the current-voltage characteristics were measured. We have observed that the current-voltage characteristics shows a reversible current maxima at low voltage, which is possibly not related to the emission from Alq$_3$. Current-voltage-luminance characteristics imply that the conduction luminance mechanism at low voltage is different from that of high voltage one.

• 한국컴퓨터산업교육학회:학술대회논문집
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• 2003.11a
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• pp.95-98
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• 2003

Power semiconductors are being currently used as a application of intelligent power inverters to a refrigerator, a washing machine and a vacuum cleaner as well as core parts of industrial system. The rating of semiconductor devices is an important factor in decision on the field of application and the forward blocking voltage is one of factors in decision of the rating. The Power MOS device has a merit of high input impedance, short switching time, and stability in temperature as well known. Power MOS devices are mainly used as switches in the field of power electronics, especially the on-state resistance and breakdown voltage are regarded as the most important parameters. Power MOS devices that enable a small size, a light weight, high-integration and relatively high voltage are required these days. In this paper, we proposed the new lateral power MOS which has forward blocking voltage of 250V and contains trench electrodes and verified manufactural possibility by using TSUPREM-4 that is process simulator.

• Journal of the Korean institute of surface engineering
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• v.55 no.5
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• pp.292-298
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• 2022

In this study, PEO (plasma electrolytic oxidation) film formation behavior of AZ31 Mg alloy under application of 300 Hz pulse current was studied by the analyses of V-t curve, arc generation behavior, PEO film thickness and morphology of PEO films with treatment time in 0.05 M NaOH + 0.05 M Na₂SiO₃ + 0.1 M NaF solution. PEO films was observed to grow after 10 s of application of pulse current together with generation of micro-arcs. PEO film grew linearly with treatment time at a growth rate of about 5.58 ㎛/min at 200 mA/cm² of pulse current but increasing rate of film formation voltage became lowered largely with increasing treatment time after passing about 250 V, suggesting that resistivity of PEO films during micro-arc generation decreases with increasing film formation voltage at more than 250 V.

• Proceedings of the KIEE Conference
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• 1999.11a
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• pp.56-60
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• 1999

This paper presents the high performance real time control system of PWM inverter for uninterruptible power supply(UPS). This system is based on a digital control scheme which calculates the pulse widths of the inverter switches for the next sampling time in digital signal processor(DSP). A PI compensator is used to eliminate the voltage error caused by the difference between the actual values of LC filter and those designed. Double regulation loops which are the inner current loop and the outer voltage loop are used to make the transient response time reduce in load disturbance and nonlinear load. This method makes it possible to obtain better response in comparison to conventional digital control system. The proposed scheme provides good performance such as stable operation, low THD of the output voltage, and good dynamic response for load variations and nonlinear load.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1329-1330
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• 2007

Phase-change random access memory(PRAM) has many advantages compare with the existing memory. For example, fast programming speed, low programming voltage, high sensing margin, low power consume and long cyclability of read/write. Though it has many advantages, there are some points which must be improved. So, we invented and studied new constitution of $Ge_{1}Se_{1}Te_{2}$ chalcogenide material. Actually, the performance properties have been improved surprisingly. However, crystallization time was as long as ever for amorphization time. In this paper, we studied in order to make set operation time and reset operation voltage reduced. In the present work, by alloying Sb in $Ge_{1}Se_{1}Te_{2}$. we could confirm that improved its set operation time and reset operation voltage. As a result, the method of Sb-alloyed $Ge_{1}Se_{1}Te_{2}$ can be solution to decrease the set operation time and reset operation voltage.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.5
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• pp.597-605
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• 2018

In this study, we demonstrated the inhibitory effect of the Class Ic antiarrhythmic agent propafenone on voltage-dependent $K^+$ (Kv) channels using freshly isolated coronary artery smooth muscle cells from rabbits. The Kv current amplitude was progressively inhibited by propafenone in a dose-dependent manner, with an apparent $IC_{50}$ value of $5.04{\pm}1.05{\mu}M$ and a Hill coefficient of $0.78{\pm}0.06$. The application of propafenone had no significant effect on the steady-state activation and inactivation curves, indicating that propafenone did not affect the voltage-sensitivity of Kv channels. The application of train pulses at frequencies of 1 or 2 Hz progressively increased the propafenone-induced inhibition of the Kv current. Furthermore, the inactivation recovery time constant was increased after the application of propafenone, suggesting that the inhibitory action of propafenone on Kv current is partially use-dependent. Pretreatment with Kv1.5, Kv2.1 or Kv7 inhibitor did not change the inhibitory effect of propafenone on the Kv current. Together, these results suggest that propafenone inhibits the vascular Kv channels in a dose- and use-dependent manner, regardless of $Na^+$ channel inhibition.