• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1718-1719
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• 2008

본 논문에서는 철도차량의 능동조향을 위한 고전 PI 제어기 및 퍼지 제어기를 설계하여 그 성능을 서로 비교하였다. 철도차량에서 능동조향은 곡선부 주행 시 발생되는 승차감 저하 및 차륜/레일의 마모와 소음을 줄이고, 고속주행을 위한 조향성능 및 주행안정성을 확보하기 위한 제어기술이다. 논문에서는 차량 1량을 모델로 하여 측정된 휠-레일의 횡변위(Lateral Displacement) 정보를 토대로 휠의 요모멘트를 제어하는 전략을 사용하여 제어기를 설계하였으며, 시뮬레이션을 통해 제어기 응답 특성을 비교하였다.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.110-122
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• 1996

본 논문에서는 전기유동유체(Electro-Rheological Fluid : ERF)를 함유하는 지능구조물의 동적 모델링 및 진동제어를 수행하였다. 먼저 실리콘 오일을 기본용매로 하여 조성된 ERF의 복소 전단모듈러스를 전장부하와 가진 주파수의 함수로 동적 회전모드 실험을 통하여 도출한 후, 이를 샌드위치 보 이론과 연계하여 동적 모델링을 실시하였다. 도출된 6차 편미분방정식 형태의 지배 방정식을 유한요소 모델로 이산화하여 전장부하에 따른 지능구조물의 동탄성 특성값인 감쇠 고유 주파수 및 모달 손실계수를 주파수 영역에서 얻었다. 그리고 ERF를 함유한 샌드위치 형태의 지능구조물을 제작한 후 실험적으로 얻은 동탄성 특성값과 모델에 의해 예측된 동탄성 특성값을 비교 고찰하여 제시된 동적 모델에 대한 타당성을 입증하였다. 또한 모델을 통해 전장부하 함수로 예측된 주파수 응답곡선 중에서 각 주파수 대역에 대해 최소 변위가 되는 응답곡선을 요구응답으로 설정한 후, 그에 해당하는 전장부하를 선정하는 논리적인 능동 진동제어 알고리즘을 제안하였다. 제어알고리즘의 유용성을 입증하기 위해 실험적으로 수행된 능동 진동제어 결과를 주파수영역과 시간영역에서 제시하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1757_1758
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• 2009

본 논문에서는 철도차량의 능동조향시스템 연구를 위한 축소 조향대차의 장애물 검지시스템 구축에 대여 연구하였다. 철도차량에서 능동조향이란 곡선부 주행 시 차륜/레일 접촉에 의한 승차감 저하 및 차륜/레일의 마모와 소음을 줄이고, 고속주행을 위한 조향성능 및 주행안정성을 확보하기 위한 휠셋의 제어기술이다. 따라서 논문에서는 조향제어전략 및 제어기법을 연구하기 위한 축소 차량모델(견인대차와 조향대차로 구성)의 개발과정으로서 자동운전을 위한 장애물 검지시스템에 대한 연구를 수행하였으며 주행실험을 통해 그 성능을 검증하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.172-180
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• 2009

Normally in order to build a semi-active control system equipped with MR damper, the dynamic modeling of the damper is required to numerically predict its dynamic damping force and also its behavioral characteristics. For the dynamic modeling of the MR damper, this paper attempts to predict and evaluate its dynamic behavior by applying specifically both a power model and a Bingham model. Dynamic loading tests were performed on the squeeze type of damper specially designed for this research, and force-displacement hysteresis loops confirmed the effectiveness of the damper as a semi-active control device. In the meantime, in order to evaluate the effectiveness of each model applied, the model parameter for each model was identified. On the basis of the parameter, we derived the error ratio of the force-velocity relationship curve and the dynamic damping force, which was contrasted and compared with the experimental results of the squeeze type of damper. Finally, the squeeze type of MR damper developed in this research was proved to be valid as a semi-active control device, and also the evaluation of the two dynamic models showed they were working fine so that they were likely to be easily utilized to numerically predict the dynamic characteristics of any dampers with MR fluid as well as the squeeze type of MR damper.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.5
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• pp.465-474
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• 2008

The real-time hybrid testing method(RT-HYTEM) is a structural testing technique in which the numerical integration of the equation of motion for a numerical substructure and the physical testing for an experimental substructure are performed simultaneously in real-time. This study presents the quantitative evaluation of the seismic performance of a building structure installed with an passive and semi-active MR damper by using RT-HYTEM. The building model that was identified from the force-vibration testing results of a real-scaled 5-story building is used as the numerical substructure, and an MR damper corresponding to an experimental substructure is physically tested by using the universal testing machine(UTM). The RT-HYTEM implemented in this study is validated because the real-time hybrid testing results obtained by application of sinusoidal and earthquake excitations and the corresponding analytical results obtained by using the Bouc-Wen model as the control force of the MR damper respect to input currents were in good agreement. Also for preliminary study, some semi-active control algorithms were applied to the MR damper in order to control the structural responses optimally. Comparing between the test results of semi-active control using RT-HYTEM and numerical analysis results show that the RT-HYTEM is more resonable than numerical analysis to evaluate the performance of semi-active control algorithms.

• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.186-189
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• 1993

능동 소나 체계에서 표적의 탐지거리 예측을 위하여 소나방정식이 이용되는데, 이는 음원 준위, 전달 손실, 표적 강도, 복반사 준위, 소음 준위, 방향성 이득, Detection threshold, Signal excess, 탐지 확률과 탐지거리의 요소로 구성된다. 본 연구에서는 능동 소나 체계에서 소나 깊이와 표적 깊이의 함수인 탐지거리를 계산하기 위한 알고리즘에 대해 살펴보았다. 소나의 각 요소와 환경이 주어졌을 때 SAFARI 모델을 이용하여 각 수신기의 깊이와 거리에서의 전달손실을 계산하였으며, 구하여진 전달 손실과 배경 소음 준위를 이용하여 Signal excess를 계산하였다. ROC(Receiver-operating-characteristic) 곡선을 이용하여 Signal excess를 탐지 확률로 계산한 후 두 항을 곱하여 각 깊이별 거리로 적분함으로서 탐지거리를 구하였다. 주파수 30Hz의 전방향 음원을 사용하여 여름의 일반적 음속 분포에서 계산한 결과 100m 음원 보다 300m 음원에서 상대적으로 큰 탐지거리를 얻었으며 각 음원 깊이별 평균 탐지거리는 100m 이하의 표면을 제외한 500m 까지는 거의 일정함을 알 수 있었다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1591-1592
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• 2007

본 논문에서는 상태궤환을 이용한 철도차량의 능동조향을 위한 제어기법에 대해 다루었다. 능동조향은 곡선부 주행시 발생되는 승차감 저하 및 차륜/레일의 마모, 소음을 줄이고 고속주행을 위한 조향성능 및 주행안정성을 확보하기 위한 기술이다. 논문에서 사용된 제어 방법은 반대차(Half Bogie) 차량모델을 기초로 측정된 휠-레일의 횡변위(Lateral Displacement) 와 요각(Yaw Ang;e)정보를 토대로 휠에 요모멘트를 제어하였으며 시뮬레이션을 통해 제안한 방법에 대한 성능을 검증하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.61-69
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• 2013

This research is aimed to evaluate characteristics and dynamic modeling of MR damper for semi-active vibration control. A MR damper of semi-active type was designed and made for the purpose of controlling the vibration of a real-size model structure. Usually a semi-active control system equipped with a MR damper requires a dynamic model which expresses numerical data about the damping capacity and dynamic characteristics generated by a MR damper. To fulfil the requirement, a Power model and a Bingham model were particularly employed among many dynamic models of MR damper. Those models being contrasted with other ones, a dynamic test was carried out on the developed MR damper. In the test, excitation frequencies were conditioned to be 0.15 Hz, 1.0 Hz, and 2.0 Hz, and three different currents were adopted for each frequency. From these test results, it was found that displacement affected control capacity of the MR damper. The test results led to the identification of model variables for each dynamic model, on the basis of which a force-speed relation curve and expected damping force were derived and contrasted to those of the developed MR damper. Therefore, it was proven that the MR damper designed and made in this research was effective as a semi-active controller, and also that displacement of 2mm at minimum was found to be secured for vibration control, through the test using various displacements.

• Journal of Internet Computing and Services
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• v.13 no.4
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• pp.53-62
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• 2012

Object segmentation is a demanding research area and not a trivial problem of image processing and computer vision. Tremendous segmentation algorithms were addressed on gray-scale (or biomedical) images that rely on numerous image features as well as their strategies. These works in practice cannot apply to natural color images because of their negative effects to color values due to the use of gray-scale gradient information. In this paper, we proposed a new approach for color object segmentation by modifying a geometric active contour model named distance regularized level set evolution (DRLSE). Its speed function will be designed to exploit as much as possible color gradient information of images. Finally, we provide experiments to show performance of our method with respect to its accuracy and time efficiency using various color images.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.709-716
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• 2007

An active steering bogie has been theoretically proved to improve both stability and steering performance remarkably. However, It has not been commercialized yet even though many researchers have been trying to develop it because some technical difficulties still exist such as information acquisition fer active control, increasing mechanical components, high energy consumption, fail-safe problem and so on. To solve those problems, an advanced active steering mechanism is proposed in this paper. With this mechanism, required control force is small enough to use direct drives. Therefore, the number of additional mechanical components can be minimized since mechanical transducers like gears are not necessary. Fail-safe function can be also inserted easily. In this paper, concept design of the proposed active steering bogie is introduced and the possibility is verified through computer simulation using linear dynamic model.