• 한국도로학회논문집
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• 제15권5호
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• pp.177-185
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• 2013

PURPOSES : This study attempts to design and establish the road surface condition detection system by using the image processing that is expected to help implement the low-cost and high-efficiency road information detection system by examining technology trends in the field of road surface condition information detection and related case studies. METHODS : Adapted visual information collecting method(setting a stereo camera outside of the vehicle) and visual information algorithm(transform a Wavelet Transform, using the K-means clustering) Experiments and Analysis on Real-road, just as four states(Dry, Wet, Snow, Ice). RESULTS : Test results showed that detection rate of 95% or more was found under the wet road surface, and the detection rate of 85% or more in snowy road surface. However, the low detection rate of 30% was found under the icy road surface. CONCLUSIONS : As a method to improve the detection rate of the mobile road surface condition information detection system developed in this study, more accurate phase analysis in the image processing process was needed. If periodic synchronization through automatic settings of the camera according to weather or ambient light was not made at the time of image acquisition, a significant change in the values of polarization coefficients occurs.

• 대한기계학회논문집A
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• 제33권5호
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• pp.455-462
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• 2009

This paper presents design concepts of a reconfigurable mobile robot for both of indoor and outdoor applications. A linkage mechanism and wheel-in-motors give the proposed mobile robot various driving modes in maneuver and good adaptability to irregular surface. Since the mobile robot receives multiple sensor signals from odometers and an orientation sensor, states related to the position and the orientation of the mobile robot are optimally estimated by an extended Kalman filter. Simulations and experimental results show that the performance of dead reckoning on estimating the pose of a mobile robot can be improved remarkably by the optimal state observer.

• 대한원격탐사학회지
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• 제22권5호
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• pp.351-356
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• 2006

Based on current practical needs for geo-spatial information on mobile platform, the main theme of this study is a design and implementation of dynamic 3D terrain rendering system using spaceborne imagery, as a kind of texture image for photo-realistic 3D scene generation on mobile environment. Image processing and 3D graphic techniques and algorithms, such as TIN-based vertex generation with regular spacing elevation data for generating 3D terrain surface, image tiling and image-vertex texturing in order to resolve limited resource of mobile devices, were applied and implemented by using graphic pipeline of OpenGL|ES (Embedded System) API. Through this implementation and its tested results with actual data sets of DEM and satellite imagery, we demonstrated the realizable possibility and adaptation of complex typed and large sized 3D geo-spatial information in mobile devices. This prototype system can be used to mobile 3D applications with DEM and satellite imagery in near future.

• Journal of Computing Science and Engineering
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• 제5권3호
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• pp.210-222
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• 2011

In this work, we study the problem of privacy-preservation data publishing in moving objects databases. In particular, the trajectory of a mobile user in a plane is no longer a polyline in a two-dimensional space, instead it is a two-dimensional surface of fixed width $2A_{min}$, where $A_{min}$ defines the semi-diameter of the minimum spatial circular extent that must replace the real location of the mobile user on the XY-plane, in the anonymized (kNN) request. The desired anonymity is not achieved and the entire system becomes vulnerable to attackers, since a malicious attacker can observe that during the time, many of the neighbors' ids change, except for a small number of users. Thus, we reinforce the privacy model by clustering the mobile users according to their motion patterns in (u, ${\theta}$) plane, where u and ${\theta}$ define the velocity measure and the motion direction (angle) respectively. In this case, the anonymized (kNN) request looks up neighbors, who belong to the same cluster with the mobile requester in (u, ${\theta}$) space: Thus, we know that the trajectory of the k-anonymous mobile user is within this surface, but we do not know exactly where. We transform the surface's boundary poly-lines to dual points and we focus on the information distortion introduced by this space translation. We develop a set of efficient spatiotemporal access methods and we experimentally measure the impact of information distortion by comparing the performance results of the same spatiotemporal range queries executed on the original database and on the anonymized one.

• Bulletin of the Korean Chemical Society
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• 제15권1호
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• pp.15-20
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• 1994

The adsorption model in reversed phase liquid chromatography has been critically examined. It has been found that use of the Everett type surface activity coefficient for the solute in the stationary phase is not useful to study the retention characteristics of a nonpolar solute. We suggest a modified model. In this model it is assumed that the displaced modifier molecules from the surface monolayer do not transfer into the bulk mobile phase but stick to the nonpolar solute which has displaced them. In addition, we prefer to use an apparent stationary phase activity coefficient of the soluie instead of the Everett type activity coefficient. This modified adsorption model well explains the mobile and stationary phase effects on the solute retention upon variation of mobile phase composition.

• 제어로봇시스템학회논문지
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• 제19권6호
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• pp.495-500
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• 2013

This paper proposes a double sliding surfaces based on a sliding mode control for a tracking control of nonholonomic mobile robots in the Cartesian coordinates. In order to remove sliding surface constraints, we design the additional sliding surface for the heading angle with respect to the newly defined coordinates. Then, we define the switching law based on the posture error to combine the designed sliding surface with the previous one. By using the double sliding surfaces and the switching law, we obtain the control law for arbitrary trajectories. It is proved that the position tracking error and the heading direction error asymptotically converge to zero, respectively, with the Lyapunov stability theory. Finally, through computer simulations, we demonstrate the effectiveness of the proposed control system.

• 한국지능시스템학회논문지
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• 제26권1호
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• pp.16-22
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• 2016

세계적으로 수많은 로봇연구실에서 이륜 도립진자 이동로봇에 대한 연구가 진행되고 있다. 본 논문에서는 이런 이륜 도립진자 이동로봇이 평탄한 경사면에서 안정적으로 주행할 수 있도록 하는 강인 제어기를 개발하는 것으로 고려한다. 경사면에서 이륜 도립진자 이동로봇의 균형을 위해 3 자유도의 운동방정식에서 선회운동을 제한한 2 자유도 동력학식을 사용하며, 가변구조시스템 이론을 근간으로 하는 슬라이딩 모드 제어기를 제안하고 LQR 이론을 이용하여 슬라이딩 운동이 일어나는 슬라이딩 평면을 설계한다. 시뮬레이션을 위해 Mathworks사의 Simulink를 활용하여 이륜 도립진자 이동로봇의 2 자유도 모델을 실현하고, 슬라이딩 모드 제어기 또한 Simulink를 이용하여 구현한다. 시뮬레이션 결과를 통해 제안된 제어기가 경사면을 주행하는 이륜 도립진자 이동로봇을 효과적인 제어한다는 것을 보인다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.17-18
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• 2010

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.570-574
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• 1993

This paper proposes a new method of estimating the position and heading angle of a mobile robot moving on a flat surface. The proposed localization method utilizes two passive beacons and a single rotating ultrasonic sensor. The passive beacons consist of two cylinders with different diameters and reflect the ultrasonic pulses coming from the sonar sensor mounted on the mobile robot. The geometric parameter set of beacon is acquired from the sonar scan data obtained at a single mobile robot location using a new data processing algorithm. Form this parameter set, the position and heading angle of the mobile robot is determined directly. The performance and validity of the proposed method are evaluated using two beacons and a single sonar sensor attached at the pan-tilt device mounted on a mobile robot, named LCAR, in our laboratory.

• 한국게임학회 논문지
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• 제10권2호
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• pp.57-66
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• 2010

기존의 테이블탑 시스템 연구에서는 주로 프로젝션 기반의 테이블 표면에 컴퓨터 영상을 디스플레이하고 그 테이블 표면에서 사용자는 멀티 터치(Multi-touch)나 탠저블 물체 (Tangible object)로 인터랙션을 한다. 본 연구에서는 확장 가능한 테이블탑 타일드 디스플레이 시스템에서 적외선 카메라 트래킹과 PDA 모바일 인터페이스를 이용하여 다중 사용자의 인터랙션을 지원하는 FishBowl 게임을 개발하였다. 이 게임은 고화질 테이블탑 가상환경과 PDA 모바일 인터페이스가 함께 연동하여 사용자의 상호작용성과 체감을 향상시키고 상하였다. 본 논문에서는 FishBowl 게임과 시스템 설계 및 구현에 대해서 설명한다. 그리고 사용자 관찰을 통하여 발견된 시스템 유용성과 개선점을 토론하고 결론과 향후 연구 방향에 대해 논한다.