• Journal of Power Electronics
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• 제15권6호
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• pp.1547-1558
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• 2015

A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

• 한국정밀공학회지
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• 제19권9호
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• pp.157-165
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• 2002

The design of hydraulic & control system has been developed for the disc spinning machine. The hydraulic system has been designed in the overall system including the vertical & horizontal slide fur spinning works which are controlled by hydraulic servo valves in right & left side, and the clamping slide for holding & pressing blank material in center during spinning process. Based on the design concept of this hydraulic system, model test experiments for hydraulic servo control system is tested to conform confidence and applying possibility. The control system is introduced with the fuzzy-sliding mode controller for the hydraulic force control reacting force as a disturbance, because a fuzzy controller does not require an accurate mathematical model for the generation of nonlinear factors in the actual nonlinear plant with unknown disturbances and a sliding controller has the robustness & stability in mathematical control algorithm. We conform that the fuzzy-sliding mode controller has a good performance in force control for the plant with a strong disturbance. Also, we observe that a steady state error of the fuzzy-sliding mode controller can be reduced better than those of an another controllers.

• 한국초전도ㆍ저온공학회논문지
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• 제16권1호
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• pp.23-26
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• 2014

This paper represents the detection method of voltage disturbance for high temperature superconducting (HTS) tape using electromagnetically coupled coils. In order to detect the voltage as the superconductor transits from the superconducting state to the normal conduction state, voltage taps are widely used to get the voltage signal. And voltage taps are connected to data acquisition device via signal wires. However this new suggested method can detect the superconducting transition voltage without signal wires between voltage taps and data acquisition device by using electromagnetically coupled coils. This system consists of two electromagnetically coupled coils, the first coil to detect and transmit the voltage of HTS tape and the second coil to pick up the transmitted voltage from the first coil. By using this new suggested method, we can build the 'separated voltage-detection system'. HTS tape and first coil are located under liquid nitrogen vessel and the second coil is located under room temperature condition. In this paper, experiments are performed to verify the feasibility of the proposed method. As the result of the experiment, the separated voltage-detection system using electromagnetically coupled coils can successfully observe superconducting-normal transition of HTS tapes.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.33.1-33.1
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• 2008

As a part of the construction of Korean Space Weather Prediction Center (K-SWPC), Korea Astronomy and Space Science Institute (KASI) installed a Scintillation Monitor (SCINTMON) and an All-Sky Camera to observe upper atmospheric/ionospheric phenomena. The SCINTMON is installed in KASI building in Daejeon in cooperation with Cornell university and is monitoring the ionospheric scintillations on GPS L-band signals. All-Sky Camera is installed at Mt. Bohyun in Youngcheon in cooperation with Korea Polar Research Institute. It is used to take the photograph for upper atmospheric layer through appropriate filters with specific airglow or auroral emission wavelengths and to observe upper atmospheric disturbance, propagation of gravity wave and aurora. The integrated data from the instruments including SCINTMON and All-Sky Camera will be used for giving nowcast on the space weather and making confidential forecast based on some space weather prediction models.

• 생명과학회지
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• 제16권7호
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• pp.1097-1103
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• 2006

Community structure varies not only in space but also in time. We stand in one position which located at Sinhung-ri, Sacheon-ci and observe the flora of area as time passes. This area begins after disturbance on sites where organisms are already present like secondary succession. In 2001, there are invaded by Trapa japonica, Salvinia natans, and Potamogon cristatus. Four or five years later, this abandoned areas support of clover, pine, and oak, resulting in a shifting pattern of species dominance and diversity through time. Patterns of community structure such as species composition and ecological diversity have shown through seasons and five years, that is the topic of this study. The values of turnover (TO) were changes through time intervals at three regions. The gradual and seemingly directional change in the structure of the community through time from aquatic like to field. Thus, we can observe the process of secondary succession at Sinhung-ri in the very short time.

• 대한한방내과학회지
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• 제28권4호
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• pp.733-740
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• 2007

Objective : This study investigated the relationship between warning signs and Sasang constitution (SC) in acute stroke patients. Methods : From October in 2005 to March in 2007, 629 acute stroke patients were studied. Patients were hospitalized within 14 days after the onset ofstroke at one of 3 oriental medical hospitals in Seoul and Kyong-gi province. We assessed the type of SC of acute stroke patients by Questionnaire for Sasang Constitution Classification II (QSCC II). We investigated warning signs (motor weakness, blindness, dysarthria, sensory disturbance, finger dullness, facial & eyelid spasm, neck stiffness), general characteristics, etc. Results : This study showed a higher proportion of Tae-eum & So-eum experience upper extremity sensory disturbance but So-yangexperience lower extremity sensory disturbance. Smoker So-eumexperience 1st & 2nd finger dullness more than non-smoker So-eum. So-eum women experience motor weakness more than So-eum men. Conclusion : Besides these results, we could observe almost no relationship between warning signs and Sasang constitution (SC) in acute stroke patients. More data from prospective cohort studies will help people better understand the relationship between warning signs and Sasang constitution (SC) in acute stroke patients.

• Journal of Astronomy and Space Sciences
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• 제25권1호
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• pp.61-70
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• 2008

태양전파교란 실시간 모니터링 시스템 구축의 일환으로 2.8GHz를 중심으로 500MHz주파수 대역을 수신할 수 있는 태양전파수신기를 제작하였다. 윤요나 등(2004)의 구동시스템을 이용하여 태양전파를 측정해본 결과 주변에 DMB 방송 및 청주국제공항 관제탑주파수등 태양전파측정을 방해하는 전파들을 발견하였다. 이 연구는 제작된 수신기의 성능을 점검하여 보고, 또 전파망원경이 설치된 충북 청주시의 충북대학교 주변의 2.8GHz 대역의 전파환경을 측정하는 실험을 수행하였다. 실제 2.649GHz와 2.874GHz에서 너무 강한 전파 신호가 존재하여 태양전파 플럭스를 측정하지 못하도록 하는 것을 확인하였다. 전파환경 측정자료를 분석해보고, 이 연구에서 제작한 수신기를 태양전파 교란 실시간 모니터링에 사용하기 위한 개선방안을 살펴보았다. 천문학적으로 중요한 주파수대 역은 향후 잘 보호되어져야 한다고 주장한다.

• 한국정보통신학회논문지
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• 제17권11호
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• pp.2499-2504
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• 2013

동적인 자세제어에 대한 응용은 다양한 외란이 존재하는 비선형 플랜트에 발생한 외란을 제거하기 위한 모든 분야에 적용할 수 있다. 또한, 발생한 외란을 어떻게 계측하는가에 따라 제어 성능이 달라질 수 있다. 본 논문의 시스템의 구성은 CAN 통신을 기반으로 3개의 리니어 액추에이터(Linear Actuator)를 동적으로 제어하도록 하였으며, 플랜트의 외란은 수평 플랜트 위에 볼(ball)을 놓아 비선형적인 외란을 가하도록 하였다. 외란에 대한 계측은 영상처리(Image Processing)를 통하여 외란을 계측하여 플랜트를 제어하도록 하였다. 이러한 비선형적인 외란을 제거하기 위하여 본 논문에서는 비선형 시스템에 대하여 제어성능이 뛰어난 신경회로망(Neural Networks)을 활용하여 기존의 PI 제어를 보완하여 하여 더욱 강인한 제어성능을 제시하고자 한다.

• 제어로봇시스템학회논문지
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• 제9권5호
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• pp.347-353
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• 2003

A nonlinear speed controller for a surface mounted permanent magnet synchronous motor (PMSM) based on a newly developed adaptive backstepping approach is presented To compensate parameter uncertainties and load torque disturbance, a nonlinear adaptive backstepping control law and adaptive law are derived systematically through virtual control input and suitable Lyapunov function. Also, speed observer without using costly speed sensor is presented. Simulation results show that the proposed controller can observe the speed and track the reference speed signal generated by a reference model.

• Environmental Engineering Research
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• 제19권4호
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• pp.355-361
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• 2014

The wastewater treatment with a two-phase expanded granular sludge bed (EGSB) system for anaerobic degradation of acetate, benzoate, terephtalate and p-toluate from purified terephtalic acid (PTA) production was studied. The feasibility and effectiveness of the system was evaluated in terms of organic oxidation by chemical oxygen demand (COD), gas production, bacterial adaptability and stability in the granular sludge. Average removal efficiencies 93.5% and 72.7% were achieved in the EGSB reactors under volumetric loading rates of $1.0-15kg-COD/m^3/day$ and terephtalate and p-toluate of 351-526 mg/L, respectively. Gas production reached total methane production rate of 0.30 L/g-COD under these conditions in the sequential EGSB reactor system. Higher strength influent COD concentration above 4.8 g-COD/L related to field conditions was fed to observe the disturbance of the EGSB reactors.