• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.91-97
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• 2010

In this paper, we present simulation results of Dynamic Matrix Control (DMC) to a Once-through boiler steam temperature. In order to control the steam temperatures, we choose spray and damper as two input variables. Then, the step response model is generated for the two major output variables by step test. After that, on-line optimization is performed using $(2\times2)$ step response model. Proposed controller is applied to the APESS (Doosan company's boiler model simulator) and the simulation results show satisfactory performance of proposed control.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.237-237
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• 2010

고효율의 열전특성을 갖는 나노 구조체 열전재료 연구의 일환으로 이종물질인 $Bi_2Te_3$-PbTe계 열전소재의 미세구조와 특성을 조사하였다. 계단식 냉각법(step cooling)를 통하여 시편을 제조 하였고, EPMA를 이용하여 시편의 미세구조를 관찰하였다. 열전소재의 상분리를 유도하기 위하여 $700^{\circ}C$에서 용융 후 3일 동안 $400^{\circ}C$로 유지시킨 후 상온까지 용융로에서 서냉하였다. EPMA를 이용하여 제조된 시편의 미세구조와 정량 분석을 하였고, 각 상의 결정구조 확인을 위하여 XRD 분석법을 이용하여 다결정의 PbTe와 $Bi_2Te_3$ 그리고 준안정상인 $PbBi_2Te_4$가 관찰 되었다. 계단식 냉각법을 통한 시편의 열전특성을 측정하였다. 이를 통하여 제조된 시편은 급속 냉각법으로 제조된 시편과 비교되었으며, 제벡계수는와 열전도도는 상온에서 각각 약 -100mV/K와 0.9W/mK로 약90%, 40%의 열전특성 향상을 확인하였다.

• Journal of IKEEE
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• v.22 no.2
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• pp.309-315
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• 2018

A Stepped Frequency Radar(SFR) is a method of achieving high range resolution by gradually increasing the frequency of a transmitted pulse to create a wide synthetic bandwidth. However, in the case of moving target, accurate range estimation can not be performed due to the range-Doppler coupling phenomenon, so it is necessary to compensate through accurate velocity estimation. In this paper, we propose a stepped frequency radar waveform with a Coherent Pulse Train(CPT), velocity estimation results according to parameters using this method and VMD(Velocity Measurement Data) were compared and analyzed by numerical simulations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.71-78
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• 1989

The imput-output relations for nonlinear systems can be explicitly represented by the Volterra series and they can be characterized by the Volterra kernels. This study is concerned with modeling an elastomer force-displacement relation due to step inputs by utilizing the truncated Volterra series. Since it is practically impossible to apply step inputs that have infinite slope at zero time, the loads due to constant penetration(displacement) rate followed by constant penetration inputs are measured as an alternative approach and estimated for step inputs and then utilized for the truncated Volterra series models. One second order and one third order truncated Volterra series models have been employed to model the force-displacement relation which is one of the prominent properties to characterize the viscoelastic material. The third order truncated Volterra series model has better results, compared with those of the second order truncated Volterra series model.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.312-317
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• 2001

Modifying effects of the rectangular forward step for suppressing the unsteady pressure fluctuation during interaction between the upstream vortical flow with the edge are studied numerically. The vortical flow is modeled by a point vortex, and the unsteady pressure coefficient is obtained from the velocity and the potential field. To investigate the effects of the edge shape the rectangular forward step is chamfered with various angles. Calculation show that the pressure peaks become decreased by increasing the vortex height as well as the chamfering angle. The pressure amplitudes are very sensitive to the change of the initial vortex height. From this study we can find out that the chamfered edge has two effects; the one is that it suppresses the pressure amplitude generated from the edge, and the other is that it decreases the time variation of unsteady pressure fluctuation. These modifying concepts can be applied to attenuate the self-sustained oscillation mechanism at the open cavity flow.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.47-52
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• 2013

A novel architecture to reduce dramatically the coupling length of multimode interference-based couplers (MMICs) is proposed by replacing conventionally designed MMICs by cascaded two-section plasmonic stepped MMICs (PS-MMIC). For the 60% cross power splitting ratio in a stepped-width MMIC, the coupling length of device results in around 42% length reduction. Furthermore, the power splitting ratio and coupling length of plasmonic MMIC just vary around 1~2% along the variation of refractive index. On the contrast, those factors for the variation of MMIC's width strongly vary around 30~40%.

• Journal of IKEEE
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• v.22 no.3
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• pp.599-604
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• 2018

A Stepped Frequency Radar(SFR) is a method that realizes high resolution range estimation by increasing the frequency of transmission pulses at regular intervals to generate a wide synthetic bandwidth. However, in the case of a moving target, accurate range estimation becomes difficult due to the range-Doppler coupling. In this paper, the process of high resolution range estimation by compensation of the range-Doppler coupling with estimated velocity of the moving target using the SFR waveform with Coherent Pulse Train(CPT) is analyzed and it was verified through simulation.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.319-323
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• 1997

Perforated ray cells are identified for the first time in the Korean species of Deutzia glabrata, Deutzia sieboldiana, Hydrangea paniculata, and Philadelphus schrenckii that belong to Hydrangeaceae but not observed in Deutzia gracilis. These ray cells have simple to scalarifrom perforations in Deutzia glabrata which have vessel elements with scalariform perforations, and have scalariform to reticulate perforations in Deutzia sieboldiana, Hydrangea paniculata, and Philadelphus schrenckii which have vessel elements with scalariform perforations. Thus, the perforations of ray cells in Korean Hydrangeaceae appeared not to be exactly the same as the types of scalariform perforation plates in the vessel elements of same wood.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1653-1658
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• 2011

A novel circuit structure of dual-band bandstop filters is proposed in this paper. This structure comprises two shunt-connected tri-section stepped impedance resonators with a transmission line in between. Theoretical analysis from the equivalent circuit and design procedures are described. We represented graphs for filter design from the derived synthesis equations by resonance condition of circuits. Notably, advantages of the proposed filter structure are compact size in design, wide range of realizable resonance frequency ratio, and more realizable impedances.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.273-279
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• 1998

In this paper, the proposed charging system consists of step charging mode and time-sharing equalization charging mode. As $\Delta$V=O point is detected, the proposed cut-off method will selectively cut off the only battery to reach the $\Delta$V=O point, preventing serial-connected batteries from undercharging. In the start of each step, the equalization charging mode is performed to reduce the capacity difference among the batteries. Though it is added to simple circuit for selective cut-off, comparing with recently used step-charging method, this system can improve the life cycle of battery and charging efficiency, and be also very effective for preventing the batteries from overcharging and undercharging.