• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.688-693
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• 2009

The response characteristics of power system frequency are determined by generator droop characteristics and load damping properties. The characteristics of governor droops are termed by generators constant, while those of load damping by load constant. In this paper, the generator constant and the load constant are assessed by measured data at the event of generator trips.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.57-60
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• 1999

In many radio communication environments, there is a special component, called inter-symbol interference (ISI), mused by multipath time delay of signal and ISI components impose limitation of the data transmission rate. In this paper, we consider signaling pulse shapes, called partial response signaling (PRS), for minimizing the effect of ISI and show the improvement of performance by applying one of the partial-response signaling (PRS) pulses to two types of receiver system under dependent noise environments through the Monte-Carlo computer simulations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.247-250
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• 2002

SAW filters were fabricated on $LiNbO_3$ substrates to evaluate frequency response and properties of photolithography. In the both of etch and lift-off methods, lift off method was superior to etch method in fabrication process. Frequency response property was measured by network analyzer. From measurement of acoustic property, SAW propagation velocity was 3574.9m/sec for $LiNbO_3$ SAW filter.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.195-196
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• 2000

Fast response time is realized by using LTN-LCDs. To calculate the dynamic electro-optical characteristics, Ericksen-Leslie theory is used for the dynamic profile of molecules and order tensor representation is adopted for the free energy calculation.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1719-1728
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• 2017

Recent concerns about environmental conditions have triggered the growing interest in using green energy resources. These sources of energy, however, bring new challenges mainly due to their uncertainty and intermittency. In order to alleviate the concerns on the penetration of intermittent energy resources, this paper investigates impacts of realizing demand-side potentials. Among different demand-side management programs, this paper considers demand response wherein consumers change their consumption pattern in response to changing prices. The research studies demand response potentials from different load sectors on generation system well-being. Consumers' sensitivity to time-varying prices is captured via self and cross elasticity coefficients. In the calculation of well-being indices, sequential Monte Carlo simulation approach is accompanied with fuzzy logic. Finally, IEEE-RTS is used as the test bed to conduct several simulations and the associated results are thoroughly discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1005-1011
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• 2015

This paper proposes the DC offset compensation algorithm with fast response to the sensed grid voltage in the single-phase grid connected inverter. If the sensor of the grid voltage has problems, the DC offset of the grid voltage can be generated. This error must be resolved because the DC offset can generate the estimated grid frequency error of the phase-locked loop (PLL). In conventional algorithm to compensate the DC offset, the DC offset is estimated by integrating the synchronous reference frame d-axis voltage during one period of the grid voltage. The conventional algorithm has a drawback that is a slow dynamic response because monitoring the one period of the grid voltage is required. the proposed algorithm has fast dynamic response because the DC offset is consecutively estimated by transforming the d-axis voltage to synchronous reference frame without monitoring one cycle time of the grid voltage. The proposed algorithm is verified from PSIM simulation and the experiment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2302-2322
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• 2012

Wireless Body Area Networks (WBANs) are introduced as an enabling technology in tele-health for patient monitoring. Designing an efficient Medium Access Control (MAC) protocol is the main challenge in WBANs because of their various applications and strict requirements such as low level of energy consumption, low transmission delay, the wide range of data rates and prioritizing emergency data. In this paper, we propose a new MAC protocol to provide different requirements of WBANs targeted for medical applications. The proposed MAC provides an efficient emergency response mechanism by considering the correlation between medical signals. It also reduces the power consumption of nodes by minimizing contention access, reducing the probability of the collision and using an efficient synchronization algorithm. In addition, the proposed MAC protocol increases the data rate of the nodes by allocating the resources according to the condition of the network. Analytical and simulation results show that the proposed MAC protocol outperforms IEEE 802.15.4 MAC protocol in terms of power consumption level as well as the average response delay. Also, the comparison results of the proposed MAC with IEEE 802.15.6 MAC protocol show a tradeoff between average response delay and medical data rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.129-134
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• 2012

We analyzed the movement and response time of charged particles according to particle-inserting methods to understand the variation of quantity of q/m of charged particles, which is a very important factor in electrical and optical characteristics of the charged particle type display, such as lifetime, response time, contrast ratio, reflectivity, etc. For our study we used white and black charged particles of which diameter is $20{\mu}m$, prepared pieces of ITO(indium tin oxide) coated glass substrate, and formed ribs on the glass substrates. The width of a rib is $30{\mu}m$ and the cell size is $220{\mu}m{\times}220{\mu}m$. As the particle-inserting methods, the white and black charged particles were respectively inserted into a front and a rear panel with a very small electric field and also the mixture of the white and black charged particles were inserted into a rear panel. As a result of the driving characteristics of charged particles, the factors about variation of quantity of q/m according to the particle inserting method was experimentally demonstrate, showing very different driving voltage, response time, the particle movement, etc.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.568-579
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• 2018

Virtual power plants can be regarded as systems that have entered the network after restructure of power systems. In fact, these plants are a set of consumers capable of consuming and generating power. In response to widespread implementation of plug-in hybrid electric vehicles, further investigation of energy management in this type of power plants seems to be of great value. In effect, these vehicles are able to receive and inject power from/into the network. Hence, study of the effects of these vehicles on management of virtual power plants seems to be illuminative. In this paper, management of power consumption/generation in virtual power plants has been investigated in the presence of hybrid electric vehicles. The objective function of virtual power plants problem management is to minimize the overall costs including not only the costs of energy production in power generation units, fuels, and degradation of batteries of vehicles, but also the costs of purchasing electricity from the network. Furthermore, the constraints on the operational of plants, loads and hybrid vehicles, level of penalty for greenhouse gas emissions ($CO_2$ and $NO_x$) produced by power plants and vehicles, and demand response to the immediate price of market have all been attended to in the present study. GAMS/Cplex software system and sample power system have been employed to pursue computer implementation and simulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.379-384
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• 1999

Langmuir-Blodgett(LB) films which have high ordered orientation and ordering structure are fabricated by LB method which deposit the ultra-thin films of organic materials at a molecular level. The electrical characteristics of stearic acid LB ultra-thin films for the horizontal direction were investigated to develop the gas sensor using LB ultra-thin films. The optimal deposition condition to deposit the LB ultra-thin films was obtained from $\pi-A$ isotherms and the deposition status of stearic acid LB ultra-thin films was verified by the measurement of deposition ratio, UV-absorbance, and electrical properties for LB ultra-thin films. The conductivity of stearic acid LB ultra-thin films for horizontal direction was about $10_{-8}[S/cm]$. The activation energy for LB ultra-thin films with respect to variation of temperature was about 1.0[eV], which was correspond to semiconductor material. The response characteristics for organic gas were confirmed by measuring the response time, recovery time, and reproducibility of the LB ultra-thin to each organic gas. Also, the penetration and adsorption behavior of gas molecule were confirmed through the organic gas response characteristics of LB ultra-thin films with respect to temperature.