• 전기학회논문지
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• 제57권1호
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• pp.1-7
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• 2008

In this paper, we proposed the method judging whether transmission system is radial system or loop system using simple set theory. And we proposed the method judging whether power device's operation causes of blackout or not. Using proposed method, we developed automatic judgement system of radial system for preventing power device's wrong control in SCADA. Finally, we simulated a variety of case study using SCADA simulator with developed system, and verified reliability of the result and performance of developed system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.50-52
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• 1995

This paper deals with the dynamic characteristics of LIM which is controlled by constant V/f ratio and the characteristics of the Inverter acted as interface between the utility power system and LIM. Though open-loop control method is less reliable than closed-loop control method, it's commonly used because it is simple and cheap. This paper shows the consideration for dynamic characteristics of LIM under open-loop control and for Inverter.

• Structural Engineering and Mechanics
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• 제67권6호
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• pp.643-658
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• 2018

In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product's costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제3권1호
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• pp.58-65
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• 2003

In this paper, a new model, which is a Takagi-Sugeno fuzzy model, for mobile robot is presented. A controller, consisting of two loops the one of which is the inner state feedback loop designed for stability and the outer loop is a PI controller designed for tracking the reference input, is suggested. Because the robot dynamics is nonlinear, it requires the controller to be insensitive to the nonlinear term. To achieve this objective, the model is developed by well known T-S fuzzy model. The design algorithm of inner state-feedback loop is regional pole-placement. In this paper, regions, for which poles of the inner state feedback loop are lie in, are formulated by LMI's. By solving these LMI's, we can obtain the state feedback gains for T-S fuzzy system. And this paper shows that the PI controller is equivalent to the state feedback and the cost function for reference tracking is equivalent to the LQ(linear quadratic) cost. By using these properties, it is also shown in this paper that the PI controller can be obtained by solving the LQ problem.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.459-470
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• 2008

DATS는 IDACS시스템을 구성하는 3개의 서브시스템중의 하나로써 통신해양기상위성과의 RF통신링크를 통해 L-대역의 Sensor Data, LRIT, HRIT의 수신 및 S-대역 LRIT, HRIT의 송신을 담당한다. 이 논문에는 DATS의 구축 후 위성과의 접속에 필요한 기능 및 성능을 확인하는 시험 구성이 제안되어 있고 실제 수행된 결과들이 정리되어 있다. 우선 성능 확인을 위해 태양을 이용하여 G/T 및 EIRP를 측정하였고 요구되는 사양이 만족됨을 확인하였다. 기능 확인을 위해 RF loop-back test를 수행하여 DATS내부에서 MODEM/BB의 implementation loss외에는 BER열화 요인이 없음을 확인하였다. 13m 안테나와 연동하여 일본의 기상위성인 MTSAT-1R로부터 사용자 데이터인 LRIT와 HRIT를 수신 받아 영상을 복원함으로써 L-대역의 수신기능을 검증하였다. S-대역 송신 기능은 13m 안테나의 외부에 시험용 안테나를 설치하고 이로부터 S-대역 LRIT와 HRIT의 스펙트럼을 획득함으로써 확인하였다. 수행된 시험결과를 통해 DATS는 발사 후 L-대역과 S-대역을 통해 위성과 통신을 함에 있어 필요한 기능 및 성능을 만족하고 있음을 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.528-531
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• 1994

In this paper, the resonant switch model applicable to the DC and small signal analysis of the resonant converter is studied because the conventional PWM switch model can't be applied to the analysis of the resonant converter. The charge control is superior to the peak current control in QRC because QRC is operated in FM mode. So the charge control technique is adopted and used to compose the ZVS-QRC boost with feedback loop.

• 대한수학회지
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• 제49권3호
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• pp.641-658
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• 2012

The goal of this paper is to develop a nonlinear observer-based control strategy for a multi-variables continuous stirred tank reactor (CSTR). A new robust nonlinear observer is constructed to estimate the whole process state variables. The observer is coupled with a nonlinear controller, designed based on the input-output linearization for controlling the concentration and reactor temperature. The closed loop system is shown to be globally asymptotically stable based on Lyapunov arguments. Finally, computer simulations are developed for showing the performance of the proposed controller.

• 한국환경과학회지
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• 제14권2호
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• pp.157-165
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• 2005

This study was conducted to determine optimum design parameters in nitrification and denitrfication of chemical fertilizer wastewater using pilot plant, Jet Loop Reactor. The chemical fertilizer wastewater which contains low amounts of organic carbon and has a high nitrogen concentration requires a post-denitrfication system. Organic nitrogen is hydrolyzed above $86\%$, and the concentration of organic nitrogen was influent wastewater 126mg/L and of effluent wastewater 16.4mg/L, respectively. The nitrification above $90\%$ was acquired to TKN volumetric loading below $0.5\;kgTKN/m^3{\cdot}d$, TKN sludge loading below $0.1\;kgTKN/kgVSS{\cdot}d$ and SRT over 8days. The nitrification efficiency was $90\%$ or more and the maximum specific nitrification rate was $184.8\;mgTKN/L{\cdot}hr$. The denitrification rate was above $95\%$ and the concentration of $NO_3-N$ was below 20mg/L. This case was required to $3\;kgCH_3OH/kgNO_3-N$, and the effluent concentration of $NO_3^--N$ was below 20mg/L at $NO_3^--N$ volumetric loading below $0.7\;kgNO_3^--N/m^3{\cdot}d$ and v sludge loading below $0.12\;kgNO_3^-N/kgVSS{\cdot}d$. At this case, the maximum sludge production was $0.83\;kgTS/kgT-N_{re}$ and the specific denitrfication rate was $5.5\;mgNO_3-N/gVSS{\cdot}h$.

• 한국초전도ㆍ저온공학회논문지
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• 제8권1호
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• pp.59-64
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• 2006

A closed-loop cryogenic cooling system for high field magnets is presented. This design is motivated by our recent development of cooling system for 21 tesla Fourier Transform ion Cyclotron Resonance (FT-ICR) superconducting magnets without any replenishment of cryogen. The low temperature superconducting magnets are immersed in a subcooled 1.8 K bath, which is connected hydraulically to the 4.2 K reservoir through a narrow channel. Saturated liquid helium is cooled by Joule-Thomson heat exchanger and flows through the JT valve, isenthalpically dropping its pressure to approximately 1 6 kPa, corresponding saturation temperature of 1.8 K. Helium gas exhausted from pump is now recondensed by two-stage cryocooler located after vapor purify system. The amount of cryogenic Heat loads and required mass flow rate through closed-loop are estimated by a relevant heat transfer analysis, from which dimensions of JT heat exchanger and He II heat exchanger are determined. The detailed design of cryocooler heat exchanger for helium recondensing is performed. The effect of cryogenic loads, especially superfluid heat leak through the gap of weight load relief valve, on the dimensions of cryogenic system is also investigated.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.21-26
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• 2003

We designed and constructed a multichannel superconducting quantum interference device (SQUID) magnetometer system to measure magnetic fields from the human brain. We used a new type of SQUID, the double relaxation oscillation SQUID (DROS). With high flux-to-voltage transfers of the DROS, about 10 times larger than the dc SQUIDs, simple flux-locked loop circuits could be used for SQUID operation. Also the large modulation voltage of the DROS, typically being 100 $mutextrm{V}$, enabled stable flux-locked loop operation against the thermal offset voltage drift of the preamplifier. The magnetometers were fabricated using the Nb/AlOx/Nb junction technology. The SQUID system consists of 37 signal magnetometers, distributed on a semispherical surface, and 11 reference channels were installed to pickup background noises. External feedback was used to eliminate the magnetic coupling with the adjacent channels. The liquid helium dewar has a capacity of 29 L and boil-off rate of about 4 L/d with the total 48 channel insert. The magnetometer system has an average noise level of 3 fT/√Hz at 100 Hz, inside a shielded loon, and was applied to measure auditory-evoked fields.