• 제어로봇시스템학회논문지
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• 제18권5호
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• pp.496-501
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• 2012

An equilibrium point of a WIP (Wheeled Inverted Pendulum) with changing its center of gravity is derived and validated by various numerical simulations. Generally, the WIP has two equilibrium points which are unstable and stable one. The unstable one is interested in this study. To keep the WIP over the unstable equilibrium point, the WIP is consistently being adjusted. A state feedback controller for the WIP needs a control reference for the equilibrium point. The control reference can be obtained by studying an equilibrium point of the WIP based on statics. By using Lagrange method, this study is deriving dynamic equations of the WIP both with and without changing its center of gravity. Various numerical simulations are carried out to show the validation of the equilibrium point.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2009년도 춘계학술발표회 논문집
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• pp.133-134
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• 2009

This study deals with a mobile terminal without connection to a network-server-program contained detail information of control-point reading ID consisted of latitude and longitude, following directly checking location on a control-point based on RFID.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.587-592
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair, because the sensor-actuator pair has strictly positive real (SPR) property. In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB sho robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a 'skyhook' damper, but the point sensor-distributed actuator pair with DVFB acts as a 'skyhook' rotational dmaper pair.ational dmaper pair.

• 한국소음진동공학회논문집
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• 제14권7호
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• pp.619-625
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.

• Journal of Power Electronics
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• 제15권5호
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• pp.1207-1216
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• 2015

In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

• Journal of Power Electronics
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• 제18권2호
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• pp.445-455
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• 2018

A novel algorithm is proposed to regulate the neutral point potential in neutral point clamped three-level inverters. Oscillations of the neutral point potential and an unbalanced dc-link voltage cause distortions of the output voltage. Large capacitors, which make the application costly and bulky, are needed to eliminate oscillations. Thus, the algorithm proposed in this paper utilizes the finite-control-set model predictive control and the multistage medium vector to solve these issues. The proposed strategy consists of a two-step prediction and a cost function to evaluate the selected multistage medium vector. Unlike the virtual vector method, the multistage medium vector is a mixture of the virtual vector and the original vector. In addition, its amplitude is variable. The neutral point current generated by it can be used to adjust the neutral point potential. When compared with the virtual vector method, the multistage medium vector contributes to decreasing the regulation time when the modulation index is high. The vectors are rearranged to cope with the variable switching frequency of the model predictive control. Simulation and experimental results verify the validity of the proposed strategy.

• 정보관리학회지
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• 제22권1호
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• pp.229-248
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• 2005

이 연구에서는 접근점제어를 위한 국가적인 협력 모형을 전제로, 자관의 전거레코드를 별도로 구축${\cdot}$운영하면서 서지레코드와 연결하는 방안 대신, 기 구축된 국가 접근점제어 레코드를 자관의 서지레코드와 바로 연계하여 활용할 수 있는 방안을 제시하였다. 이를 위하여 ZING(Z39.50 International: Next Generation)의 SRU(Search and Retrieve URL Service) 프로토콜을 적용하여 클라이언트/서버 시스템을 구축하였다. 이 연구에서 구축한 접근점제어 시스템은 로컬기관 전거제어 시스템 구축에 소요되는 비용과 시간을 절감할 수 있으며, 전거형 선정을 배제한 접근점제어 레코드의 이용, XML 레코드 형식 및 SRU 프로토콜의 도입을 통하여 기존 전거제어 협력 모형에 비해 보다 편리하고 융통성있게 활용될 수 있을 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.451-456
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• 1991

A robust position control scheme for DC Motor is proposed based on Fuzzy Acceleration Control. Proposed control system has the similar structure that Y. Hori proposed. But the PI type acceleration controller of it is replaced by Fuzzy Logic Controller(FLC) which is known to be robust to the operating point and parameter variations. By the simulation study for a real DC Motor, we have slowed the superiority to the continuous PI acceleration controller in the view point of robustness to the operating point and parameter variations.

• 상하수도학회지
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• 제20권6호
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• pp.829-836
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• 2006

The reaction rate of denitrification is primarily affected by the utilization of organics that are usually limited in the anoxic period in a sequencing batch reactor. It is necessary to add an extemal carbon source for sufficient denitrification. An adaptive model of state-space based on the extended Kalman filter is applied to manipulate the dosage rate of extemal carbon automatically. Control strategies for denitrification have been studied to improve control performance through simulations. The normal control strategy of the constant set-point results in the overdosage of external carbon and deterioration of water quality. To prevent the overdosage of external carbon, improved control strategies such as the constrained control action, variable set-point, and variable set-point after dissolved oxygen depletion are required. More stable control is obtained through the application of the variable set-point after dissolved oxygen depletion. The converging value of the estimated denitrification coefficient reflects conditions in the reactor.

• Spatial Information Research
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• 제15권3호
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• pp.237-249
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• 2007

우리나라에는 전국적으로 약 22,000개의 국가기준점이 설치되어 있다. 그러나 국가기준점의 위치정보를 확인하기 위해서는 기준점 성과표가 필요하며, 국가 주요시설임에도 불구하고 산 정상과 같은 야외에 설치되어 있기 때문에 보호시설이 없는 상태에서 현장점검을 통해서만 관리되고 있다. 본 연구에서는 국가기준점 표석에 부착할 수 있고, 국가기준점이 설치된 환경을 고려한 특수 RFID 태그를 제작하였으며, CDMA 통신이 가능한 PDA기반 모바일 Web 시스템과 국가기준점 관제시스템을 개발하였다. 본 시스템 개발을 통하여 기준점 정보를 현장에서 파악할 수 있고, 국가기준점 관리자가 기준점의 관리 상태 및 사용 이력 등을 파악할 수 있도록 하였다. 본 시스템을 적용할 경우 전국에 산재해있는 국가기준점 정보를 누구나 손쉽게 확인할 수 있고 정보의 변화에 따른 빠른 대응이 가능하며, 관리의 효율성이 높아질 것이다. 향후 유비쿼터스 사회가 도래하면 위치정보의 중요성이 높아질 것이다. 따라서 일반인의 위치정보 확인이 용이한 RFID를 이용한 국가기준점은 측량전문가와 같은 기준점 사용자 및 관리자에게 유용할 뿐만 아니라 일반인을 대상으로 하는 위치기반 부가서비스 창출할 수 있을 것이며, 절대위치 정보 제공 측면에서도 중요한 국가 인프라가 될 것이다.