• 제어로봇시스템학회논문지
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• 제7권4호
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• pp.351-361
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• 2001

In this paper, a generalized framework called as robust internal-loop compensator(RIC) is presented, and by using this, a structural design method of sliding of sliding mode controller is proposed. First, a general sliding mode controller is derived and a stabilizing control input is designed based on Lyapunov redesign for the system in the presence of uncertainty and disturbance. And adopting the internal model following control, RIC is proposed. Next, using the structural characteristics of the proposed RIC, disturbance attenuation characteristics are analyzed and the performance of the closed-loop system is predicted. Through this analysis, it is shown that if the control gain of RIC is increased by N times, the magnitude of error is reduced to its 1/N. the proposed method is verified through experiments using a high-precision positioning system and the performance is evaluated.

• 한국지반공학회논문집
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• 제39권10호
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• pp.5-18
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• 2023

일반적인 토공사에서 사용하는 진동롤러에 의한 층다짐을 급속충격다짐(RIC)공법을 이용한 일시 다짐으로 대체하면 토공에 소요되는 공사기간을 획기적으로 단축할 수 있다. 동적하중에 의한 다짐은 모래와 같은 조립질 토사에 적합한 공법으로 인식되고 있는데, 최근에는 매립 프로젝트의 주요 재료인 모래의 공급부족으로 세립분을 함유한 토사의 사용이 점차 증가하고 있다. 따라서 RIC와 같은 동적하중에 의한 다짐공법을 적용하기 위해, 세립분을 함유한 매립재료 사용 시의 유효개량심도에 대한 검증이 필요하다. 본 연구에서는 깨끗한 모래인 Sand fill과 세립분이 함유된 Public fill에 대한 RIC공법 적용 전·후의 현장시험 결과를 비교하여 세립분 함량에 따른 RIC공법의 유효개량심도에 대한 영향을 검토하고, 콘저항치 q_c를 사용한 다짐 품질관리기준과 관련된 문제를 논의하였다. 결론적으로 세립분을 포함하는 다양한 종류의 매립토사에 대한 다짐 품질관리를 위해서는 q_c 측정값의 정규화가 필요하며, 깨끗한 모래의 상대밀도 Dr=70%에 해당하는 다짐 품질관리기준은 정규화 콘저항치 Q_tn,cs=110으로 평가되었다. 이러한 결과를 바탕으로, RIC 품질관리 시에 적용 가능한 매립토사의 세립분 함량을 고려한 심도별 q_c 품질관리기준을 제안하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.95.2-95
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• 2001

Disturbance observer(DOB) based controller design is one of the most popular methods in the field of motion control. In this paper, a generalized disturbance compensation framework, called as robust internal-loop compensator(RIC) is introduced and an advanced design method of DOB is proposed based on the RIC. Mixed sensitivity optimization problem, which is the main issue of DOB design, is solved through the parameterization of DOB in the RIC framework. Different from conventional methods, Q-filter is separated in the mixed sensitivity optimization problem and the systematic design law for the DOB is proposed. This guarantees the robustness and optimality of the DOB and also enables the design for unstable plants.

• Geomechanics and Engineering
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• 제6권5호
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• pp.487-502
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• 2014

A three dimensional finite element model was used to simulate rapid impact compaction (RIC) in loose granular soils using ABAQUS software for one impact point. The behavior of soil under impact loading was expressed using a cap-plasticity model. Numerical modeling was done for a site in Assalouyeh petrochemical complex in southern Iran to verify the results. In-situ settlements per blow were compared to those in the numerical model. Measurements of improvement by depth were obtained from the in-situ standard penetration, plate loading, and large density tests and were compared with the numerical model results. Contours of the equal relative density clearly showed the efficiency of RIC laterally and at depth. Plastic volumetric strains below the anvil and the effect of RIC set indicated that a set of 10 mm can be considered to be a threshold value for soil improvement using this method. The results showed that RIC strongly improved the soil up to 2 m in depth and commonly influenced the soil up to depths of 4 m.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 추계종합학술대회
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• pp.239-241
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• 2007

최근에 지능형 로봇분야에서 주위 카메라를 기반으로 실시간으로 환경인식 및 물체 추적 등 다양한 분야에서 연구가 활발히 진행되고 있다. 환경인식 및 물체 추적은 결국 배경과 관심물체를 분리하는 것이라고 볼 수 있는 데, 차 연산을 이용하여 물체의 움직임만을 배경으로 분리하는 방법과 물체인식을 통해 배경으로부터 분리하여 추적하는 방법에 대한 연구가 지속적으로 이루어지고 있다. 본 논문에서는 배경과 물체 사이에서 변화하는 색상의 변화를 퍼지기법을 이용하여 물체를 배경과 분리하여 실시간으로 물체를 추적하고자 한다. 실시간 물체 추적을 위해 전체영상에 대한 전역적 탐색을 통해 여러 후보 물체 중 관심물체를 배경에서 추출 후, 추출된 물체의 크기에 따른 지역탐색을 통하여 물체를 추적하는 방법이다. 그리고 본 논문에서는 ARM프로세서를 이용한 카메라시스템을 제작하여 실시간으로 영상분활을 실험하였다.

• 한국재료학회지
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• 제23권10호
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• pp.543-549
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• 2013

The purpose of this paper was to investigate the effect of a high-energy milling (HEM) process on the particle morphology and the correlation between a thermal treatment and tetragonal/monoclinic nanostructured zirconia powders obtained by a precipitation process. To eliminate chloride residue ions from hydrous zirconia, a modified washing method was used. It was found that the used washing method was effective in removing the chloride from the precipitated gel. In order to investigate the effect of a pre-milling process on the particle morphology of the precipitate, dried $Zr(OH)_4$ was milled using a HEM machine with distilled water. The particle size of the $Zr(OH)_4$ powder exposed to HEM reduced to 100~150 nm, whereas that of fresh $Zr(OH)_4$ powder without a pre-milling process had a large and irregular size of 100 nm~1.5 ${\mu}m$. Additionally, modified heat treatment process was proposed to achieve nano-sized zirconia having a pure monoclinic phase. It was evident that two-step calcining process was effective in perfectly eliminating the tetragonal phase, having a small average particle of ~100 nm with good uniformity compared to the sample calcined by a single-step process, showing a large average particle size of ~300 nm with an irregular particle shape and a broad particle size distribution. The modified method is considered to be a promising process for nano-sized zirconia having a fully monoclinic phase.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1501-1513
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• 2001

Disturbance observer, adaptive robust control, and enhanced internal model control are model based disturbance attenuation methods famous for robust motion controller which can satisfy desired performance and robustness of high-speed/high-accuracy positioning systems. In this paper, these are shown to be the same scheme with different parameterizations. To do this, a generalized framework, called as RIC(robust internal-loop compensator) is proposed and the conventional schemes are analyzed in the RIC framework. Through this analysis, it can be shown that there are inherent similarities between the schemes and advantages of the RIC in the viewpoint of controller design. This is verified through simulations and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.139-142
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• 2006

This paper describes a new method using random modulated strategies for switched reluctance machines. The proposed method is combined random turn-on, turn-off angle technique and random pulse width modulation technique. The purpose of this proposed method is to decrease harmonic spectrum, and thus reduce the emitted acoustical noise. A random generator is generated by linear congruential generator (LCG) using random pulse position (RPP) scheme. Simulation results show that the harmonic intensity of proposed method is better than that of conventional method.

• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.82-89
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• 2003

A robust motion control method is proposed fur the point-to-point position control of a XY positioning system which consists of a base cart, elastic ben and moving mass. The horizontal motion controller consists of the feedforward controller to suppress the single mode vibration of the elastic beam and the feedback controller to get the high-accuracy positioning performance of the base cart. Input preshaping vibration suppression method based on system modeling with analytic frequency equation is proposed and integrated into the robust internal-loop compensator(RIC) to increase the robustness of the whole closed-loop system The vertical motion controller is proposed based on the dual RIC structure. Through experiments, it is shown that the proposed method can stabilize the system and suppress the vibration in the presence of uncertainties and disturbances.

• 제어로봇시스템학회논문지
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• 제10권3호
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• pp.225-231
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• 2004

Disturbance observer (DOB) has been studied extensively and applied to many motion control fields during the last decades, but relatively few studies have been devoted to the development of analytic, systematic design methods for DOB itself, This paper thus aims to provide an analytic, systematic design method for DOB. To do this, DOB is structurally analyzed and the generalized disturbance compensation framework named robust internal-loop compensator (RIC) is introduced. Through this, the inherent equivalence between DOB and RIC is found, and the mixed sensitivity optimization problem of DOB is solved. Q-filter design is completely separated from the mixed sensitivity optimization problems of DOB although the proposed method has implicit .elation with Q-filter. Also, although the Q-fille. is separately designed with sensitivity function, the proposed DOB framework has the exactly same characteristic as the original DOB.