• Smart Structures and Systems
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• 제14권4호
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• pp.719-741
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• 2014

Monitoring surface cracks is important to ensure the health of concrete structures. However, traditional visual inspection to monitor the concrete cracks has disadvantages such as subjective inspection nature, associated time and cost, and possible danger to inspectors. To alter the visual inspection, a complete procedure for automated crack assessment based on adaptive digital image processing has been proposed in this study. Crack objects are extracted from the images using the subtraction with median filter and the local binarization using the Niblack's method. To adaptively. determine the optimal window sizes for the median filter and the Niblack's method without distortion of crack object an optimal filter size index (OFSI) is proposed. From the extracted crack objects using the optimal size of window, the crack objects are decomposed to the crack skeletons and edges, and the crack width is calculated using 4-connected normal line according to the orientation of the local skeleton line. For an image, a crack width nephogram is obtained to have an intuitive view of the crack distribution. The proposed procedure is verified from a test on a concrete reaction wall with various types of cracks. From the crack images with different crack widths and patterns, the widths of cracks in the order of submillimeters are calculated with high accuracy.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.571-576
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• 2015

This paper proposes an auto-parking controller for omnidirectional mobile robots. The controller uses the multi-sensor system including ultrasonic sensor and camera. The several ultrasonic sensors of robot detect the distance between robot and each wall of the parking lot. The camera detects the global position of robot by capturing the image of artificial landmarks. To improve the accuracy of position estimation, we applied the extended Kalman filter with adaptive fuzzy controller. Also we developed the fuzzy control system to reduce the settling time of parking. The experimental results are presented to verify the usefulness of the proposed controller.

• International Journal of Aeronautical and Space Sciences
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• 제13권4호
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• pp.428-434
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• 2012

Missiles suffer from flight instability problems at high angles of attack, since vortex flow over a fuselage cause lateral force to the body. To overcome this problem at a high angle of attack, the development of a real time vortex controller is needed. In this paper, Proper Orthogonal Decomposition (POD) and feedback controllers are developed for real time vortex control. The POD method is one of the most well known techniques for modeling low order models that represent the original full-order model. An adaptive control algorithm is used for real time control.

• 제어로봇시스템학회논문지
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• 제21권11호
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• pp.1044-1049
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• 2015

This paper proposes an autonomous navigation system of mobile robots for indoor corridor environment. The system uses a laser scanner but does not use reflectors. The laser scanner measures the distance between robot and structures such as wall, pillar, and fixtures. Adaptive breakpoint detector and modified IEPF (iterative endpoint fit) are developed to find mark points from the distance data. The robot path for corridor is then generated using the angle histogram of the mark points. The experimental results are finally presented to show the effectiveness of the proposed method.

• 대한조선학회논문집
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• 제31권4호
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• pp.73-81
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• 1994

선박 내항성능의 3차원적 해석을 위하여 3차원 판넬 방법을 이용한 쏘오스 분포법과 쏘오스-다이폴 분포법이 널리 이용되어 왔다. 그러나, 이 방법들을 이용하는 경우에는 내부 유동에 의한 자유표면의 공진현상에 의해 특이파수(irregular frequency)라고 불리는 파주파수에서 동유체력 계산에 큰 오차가 발생하게 되며 이런 현상을 제거하는 것은 정확한 내항성능 해석에 필수적이라 할 수 있다. 본 논문에서는 전진동요하는 선박의 운동 해석을 위하여 Wu등이 유도한 전진하면서 동요하는 Green 함수를 이용하였다. Green함수의 계산을 위하여는 어뎁티브(adaptive) 적분방법과 스트레칭(stretching) 변환 및 정류위상(stationary phase) 적분 방법을 사용하였으며 선체의 표면과 선체 내부 수선면에 특이점을 분포한 적분방정식을 도출하였다. 또한 2차원 문제를 다룬 Ohmatsu의 제안에 따라 내부 수선면에서 법선속도가 0이라는 조건을 이용하여 동요하는 문제의 불규칙파수 현상을 제거할 수 있었다. 계산은 Series 60($C_B=0.7$)에 대하여 수행되었으며 부가질량 계수, 감쇠 계수 및 파랑강제력에 대하여 기존의 연구 결과 및 실험 결과와 비교하였다.

• 터널과지하공간
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• 제32권3호
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• pp.231-242
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• 2022

본 연구에서는 지하광산에서 로봇의 위치를 추정하고, 여러 경유지를 거쳐 주행한 후 원위치로 복귀하는 ROS (Robot Operating System) 기반의 자율주행 로봇을 개발하였다. 자율주행 로봇은 SLAM (Simultaneous Localization And Mapping) 기술을 활용하여 주행 경로에 대한 전역 지도를 사전에 생성한다. 이후, 라이다 센서를 통해 측정되는 벽면의 형태와 전역 지도를 매칭하고 AMCL (Adaptive Monte Carlo Localization) 기법을 통해 데이터들을 융합하여 로봇의 위치를 보정한다. 또한, 라이다 센서를 통해 전방 주행환경을 인지하고, 장애물을 회피한다. 개발된 자율주행 로봇을 활용하여 지하광산 현장을 모사한 실내 실험장을 대상으로 주행 실험을 수행하였다. 그 결과, 자율주행 로봇은 다중 지점의 경유지에 대해 순차적으로 주행하고 장애물을 회피하며 안정적으로 복귀하는 것을 확인할 수 있었다.

• 한국멀티미디어학회논문지
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• 제15권12호
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• pp.1464-1474
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• 2012

In this paper, we propose a QoS (Quality of Service)-aware and cooperative resource reservation scheme using cross-layer link adaptation for wireless high definition video transmission through UWB (Ultra Wide Band) network with D-MAC (Distributed Medium Access Control). A wireless high definition video transmission system usually requires stable high throughput even without line-of-sight, e.g., a destination device in another room separated by a wall. Since the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme causes lots of DRP resource reservation conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. And the current WiMedia MAC standard has not considered QoS provisioning even though QoS parameters such as a range of service rates are provided to each traffic stream. Therefore, we propose Relay DRP protocol with QoS-based relay node selection criterion, which makes a relay path to avoid DRP resource reservation conflicts and guarantee QoS more stably through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and QoS provisioning.

• 미생물학회지
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• 제28권2호
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• pp.134-144
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• 1990

In order to examine that what kind of system correlated with cadmium detoxification mechanism in Klebsiella aerogenes ATCC 10031, we tried to investigate the effect of phosphate upon the detoxification and also elucidate whether the cadmium phosphate and/or polymeric Cd-Pi complex is formed actually in cell or not. As the results, it was shown that growing pattern had long lag adaptive phase of 12 hr to 24 hr, at the concentrations of 0.02 mM and 0.08 mM cadmium, respectively. Cadmium was accumulated more highly in the fraction of cell wall and membrane than in those of cytoplasm. In case of phosphate starving cells added cadmium, inorganic polyphosphate system was primarily correlated with Cd-detoxification during the lag phase for the accommodation to cadmium, on the other hand, Cd:Sulfide complex system secondarily correlated it during the stationary phase. These results implied that polyphosphate system and Cd:sulfide complex system, these two systems were operated compensatively each other. Considering the results obsdrved with EM and examined tha changes of sulfide and polyphosphate amount, it was reflected that Cd:S complex was located at the cell surface. In the results of $in-vivo^{31}$P NMR spectra in the cells with cadmium pressure, several phosphate signals arose newly from the polyphosphate region with moving chemical shift of it. This phinomenon strongly implied the actual existence of Dd:Pi comples and /or Cd:poly-P complex in the cell and also the cellular compartmentalization of cadmium detoxifying mechanism.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.19-35
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• 2010

This paper proposes a hybrid heuristic and criteria-based method of optimum design which combines the advantages of both the iterated simulated annealing (SA) algorithm and the rigorously derived optimality criteria (OC) for structural optimum design of reinforced concrete (RC) buildings under multi-load cases based on the current Chinese design codes. The entire optimum design procedure is divided into two parts: strength optimum design and stiffness optimum design. A modified SA with the strategy of adaptive feasible region is proposed to perform the discrete optimization of RC frame structures under the strength constraints. The optimum stiffness design is conducted using OC method with the optimum results of strength optimum design as the lower bounds of member size. The proposed method is integrated into the commercial software packages for building structural design, SATWE, and for finite element analysis, ANSYS, for practical applications. Finally, two practical frame-shear-wall structures (15-story and 30-story) are optimized to illustrate the effectiveness and practicality of the proposed optimum design method.

• 국제초고층학회논문집
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• 제3권1호
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• pp.35-48
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• 2014

In designing a 300 meter high skyscraper expected to be the tallest building in Japan, an earthquake-ridden country, we launched on the full-scale performance based design to ensure redundancy and establish new specifications using below new techniques. The following new techniques are applied because the existing techniques/materials are not enough to meet the established design criteria for the large-scale, irregularly-shaped building, and earth-conscious material saving and construction streamlining for reconstructing a station building are also required: ${\bullet}$ High strength materials: Concrete filled steel tube ("CFT") columns made of high-strength concrete and steels; ${\bullet}$ New joint system: Combination of outer diaphragm and aluminium spray jointing; ${\bullet}$ Various dampers including corrugated steel-plate walls, rotational friction dampers, oil dampers, and inverted-pendulum adaptive tuned mass damper (ATMD): Installed as appropriate; and ${\bullet}$ Foundation system: Piled raft foundation, soil cement earth-retaining wall construction, and beer bottle shaped high-strength CFT piles.