• 한국항행학회논문지
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• 제7권2호
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• pp.156-161
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• 2003

본 연구에서는 저가형 GPS 수신기와 자이로 및 속도계를 결합한 혼합항법시스템을 개발하여 그 정확도를 실험하였다. 본 혼합항법시스템에서는 기존의 강결합 방식이나 연결합 방식과 달리 변형된 결합방식을 채택하여 GPS 수신기나 자이로 혹은 속도계를 자유롭게 선택할 수 있도록 하였다. 실험 결과, 본 혼합항법시스템은 기존의 항법시스템보다 정확도가 향상되었으며 다중경로오차를 상당히 제거할 수 있음이 밝혀졌다. 또한 본 항법시스템은 후처리 지리정보자료획득의 측면에서 유리한 것으로 나타났다.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.861-867
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• 2006

This paper presents the robust mobile robot localization method exploiting redundant motion information acquired from three optical mice that are installed at the bottom of a mobile robot in a regular triangular form. First, we briefly introduce a low-cost optical motion sensor, HDNS-2000, and a commercial device driver development tools, WinDriver, to be used in this research. Second, we explain the basic principle of the mobile robot localization using the motion information from three optical mice, and propose the least squares based localization algorithm which is robust to the noisy measurement and partial malfunctioning of optical mice. Third, we describe the development of the experimental optical odometer using three PC optical mice and the user-friendly graphic monitoring program. Fourth, simulations and experiments are performed to demonstrate the validity of the proposed localization method and the operation of the developed optical odometer. Finally, along with the conclusion, we suggest some future work including the installation parameter calibration, the optical mouse remodelling, and the high-performance motion sensor adoption.

• 한국공간정보시스템학회 논문지
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• 제6권1호
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• pp.51-58
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• 2004

모바일 매핑시스템은 차량에 GPS(Global Positioning System), IMU(Inertial Measurement Unit), CCD 카메라 등을 탑재하고 위치 및 영상 정보를 취득하는 효율적인 방법이다. 모바일 매핑시스템은 도로 시설물 관리, 지도 갱신 등 다양한 분야에 이용되고 있다. 국외에서 개발된 모바일 매핑시스템은 각 센서의 통합 및 동기화 방안을 알 수 없으므로 업그레이드하거나 새로운 센서를 추가하기 어렵다. 본 연구에서는 모바일 매핑시스템의 개선 및 센서추가를 위해서 모바일 매핑시스템에 기본석으로 필요한 GPS, IMU, 그리고 CCD 카메라와 향후 추가될 센서인 레이저, 오도미터(Odometer) 등의 센서가 추가될 경우를 고려하여 멀티 센서 통합 및 동기화 구현 방안을 제시하였다. 또한 동기화에 필요한 각 센1서의 요구사항을 파악한 후 동기화 장비를 설계 및 제작하고 실험하였다.

• Spatial Information Research
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• 제11권3호
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• pp.291-299
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• 2003

모바일 매핑시스템은 차량에 CCD카메라와 위치측정장비(GPS/INS, Odometer 등)를 장착하고 도로에서 일정한 거리 또는 시간간격으로 지리 정보 데이터를 획득하는 이동 정보취득 시스템이다. 이러한 모바일 매핑시스템으로부터의 자료가 실시간으로 사용자에게 전달되면, 사용자는 이동국의 위치 및 지리정보 상황을 쉽게 파악할 수 있는 장점이 있다. 실시간 위치정보 제공의 방법은 PDA, 무선모뎀, 핸드폰 그리고 웹 등 여러 가지가 있을 수 있으나, 안정적이고 효율적이며, 경제적인 방법으로 웹을 통한 전송을 생각할 수 있다. 웹을 이용한 실시간 지리정보 전송을 위해서는 먼저 실시간 위치측정이 가능한 모바일 매핑시스템을 이용하여 지리정보를 취득하고 이를 웹을 통하여 전송할 수 있는 플랫폼이 필요하다. 본 연구에서는 실시간 위치정보를 취득할 수 있는 GPS/INS 시스템을 이용하여 데이터를 취득한 후 사용자가 모바일 매핑시스템의 실시간 위치정보를 확인할 수 있도록 웹으로 전송하는 플랫폼을 연구하였다.

• 제어로봇시스템학회논문지
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• 제19권4호
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• pp.372-378
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• 2013

In this paper, we research the localization problem of the crawler-type inspection robot for underwater structure which travels an outer wall of underwater structure. Since various factors of the underwater environment affect an encoder odometer, it is hard to localize robot itself using only on-board sensors. So in this research we used a depth sensor and an IMU to compensate odometer which has extreme error in the underwater environment through using Extended Kalman Filter(EKF) which is normally used in mobile robotics. To acquire valid measurements, we implemented precision sensor modeling after assuming specific situation that robot travels underwater structure. The depth sensor acquires a vertical position of robot and compensates one of the robot pose, and IMU is used to compensate a bearing. But horizontal position of robot can't be compensated by using only on-board sensors. So we proposed a localization algorithm which makes horizontal direction error bounded by using kinematics relationship. Also we implemented computer simulations and experiments in underwater environment to verify the algorithm performance.

• 농업과학연구
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• 제37권3호
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• pp.491-499
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• 2010

This study was carried out to investigate the consolidation characteristics of the remolded clay by the oedometer and the constant rate of strain(CRS) consolidation tests. As the rate of strain increases, the settlement rapidly decreased. As the ratio of the sand in the specimen increases, its effect on the rate of strain to the settlement was reduced. As the effective stress increased, the void ratio decreased, while the rate of strain increased, it did not show a clear variation. The reduction of the void ratio was shown to be less than the oedometer test. The coefficient of vertical consolidation with effective stress showed very large variation around preconsolidation stress, but the rate of strain did not provide significant effects. The rate of strain with effective stress gradually decreased at all tests and mixed ratio of sand. The rate of strain at the constant rate of strain tests showed smaller than in the oedometer test. The coefficient of consolidation at the constant rate of strain tests showed much more increase than in the oedometer test. The ratio of the vertical coefficient of consolidation by the odometer and the constant rate of strain tests showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to designing the soft ground improvement.

• 한국정밀공학회지
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• 제28권3호
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• pp.330-338
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• 2011

Odometry is the critical factor to estimate the location of the robot. In the mobile robot with wheels, odometry can be performed using the information from the encoder. However, the information of location in the encoder is inaccurate because of the errors caused by the wheel's alignment or slip. In general, visual odometer has been used to compensate for the kinetic errors of robot. In case of using the visual odometry under some robot system, the kinetic analysis is required for compensation of errors, which means that the conventional visual odometry cannot be easily applied to the implementation of the other type of the robot system. In this paper, the novel visual odometry, which employs only the single camera toward the ground, is proposed. The camera is mounted at the center of the bottom of the mobile robot. Feature points of the ground image are extracted by using median filter and color contrast filter. In addition, the linear and angular vectors of the mobile robot are calculated with feature points matching, and the visual odometry is performed by using these linear and angular vectors. The proposed odometry is verified through the experimental results of driving tests using the encoder and the new visual odometry.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.629-636
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• 2003

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1152-1154
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• 2003

The needs of 3-D data have been increasing for various applications like visualization, 3-D modeling, planning and management as well as entertainment. Mobile mapping has become a quick and practical means for acquiring necessary 3-D data for above-mentioned applications. A mobile mapping system mainly consists of two main components, viz. data acquisition devices and positioning devices. The data acquisition devices consist of CCD cameras or/and laser scanners. The positioning devices consist of GPS, INS, Odometer (shaft encoder) and some other referencing devices. The overall accuracy of mobile mapping system depends on the accuracy of positioning devices and their integrated output. Though, GPS is the main input device for the position information, the signal is not available for the computation of position all the times in urban area. The GPS satellites are normally obstructed by high-rise buildings. Thus it is very important to understand the accuracy of such a system in different environments and means to solve such problems. We have developed a mobile mapping system called VLMS (Vehicle-borne Laser Mapping System), which consists of CCD Cameras, Laser scanners, GPS, INS and Odometer. In this paper, we will present and discuss the accuracy of this system with data acquired in different environments (open area, urban area, tunnel, express way etc) by analyzing the data with respect to other existing digital data.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2001년도 추계학술발표회 논문집
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• pp.184-193
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• 2001