• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.663-670
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• 2020

In the present study, we assessed the accuracy of aerial triangulation using a UAV (Unmanned Aerial Vehicle) capable of network RTK (Real-Time Kinematic) survey in a disaster situation that may occur in a semi-urban area mixed with buildings. For a reliable survey of check points, they were installed on the roofs of buildings, and static GNSS (Global Navigation Satellite System) survey was conducted for more than four hours. For objective accuracy assessment, coded aerial targets were installed on the check points to be automatically recognized by software. At the instance of image acquisition, the 3D coordinates of the UAV camera were measured using VRS (Virtual Reference Station) method, as a kind of network RTK survey, and the 3-axial angles were achieved using IMU (Inertial Measurement Unit) and gimbal rotation measurement. As a result of estimation and update of the interior and exterior orientation parameters using Agisoft Metashape, the 3D RMSE (Root Mean Square Error) of aerial triangulation ranged from 0.153 m to 0.102 m according to the combination of the image overlap and the angle of the image acquisition. To get higher aerial triangulation accuracy, it was proved to be effective to incorporate oblique images, though it is common to increase the overlap of vertical images. Therefore, to conduct a UAV mapping in an urgent disaster site, it is necessary to acquire oblique images together rather than improving image overlap.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.3
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• pp.329-334
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• 2011

The cooling water circulation plates had been used to drop the temperature of refractory outside shell of common cooling system by using cooling plate or stave type. When they are attacked by surrounding gas, they are corroded and the water flows in the refractory due to leakage of water. So, the life of refractory material is shortened and changed due to the worse conditions of cooling system. The automatic sensing device for water leakage of cooling plate is developed to check the position of trouble by using the microprocessor system when cooling water leak and gas are flowed into the cooling plate through the leakage position. The flowed gas is detected in the micro-process system which delivers the detected position of cooling plate or stave to main control room through the wireless-radio relay station. This system can be possible to detect the position of cooling plate or stave against the water leakage part immediately and then deliver the signal to main control room by using the microprocessor system and wireless-radio relay station. This system will be developed in changing the working condition from manual system to unmanned auto alarm system.

• Journal of Ocean Engineering and Technology
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• v.17 no.1
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• pp.1-7
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• 2003

Autonomous underwater vehicles (AUVs) are unmanned, underwater vessels that are used to investigate sea environments in the study of oceanography. Docking systems are required to increase the capability of the AUVs, to recharge the batteries, and to transmit data in real time for specific underwater works, such as repented jobs at sea bed. This paper presents a visual :em control system used to dock an AUV into an underwater station. A camera mounted at the now center of the AUV is used to guide the AUV into dock. To create the visual servo control system, this paper derives an optical flow model of a camera, where the projected motions of the image plane are described with the rotational and translational velocities of the AUV. This paper combines the optical flow equation of the camera with the AUVs equation of motion, and deriver a state equation for the visual servo AUV. Further, this paper proposes a discrete-time MIMO controller, minimizing a cost function. The control inputs of the AUV are automatically generated with the projected target position on the CCD plane of the camera and with the AUVs motion. To demonstrate the effectiveness of the modeling and the control law of the visual servo AUV simulations on docking the AUV to a target station are performed with the 6-dof nonlinear equations of REMUS AUV and a CCD camera.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1791-1796
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• 2005

Semi-shield tunneling is one of the propulsion construction methods used to lay pipes underground between two pits named 'entrance' and 'destination', respectively. Usually a simple composition, such as 'a fiducial target at the entrance+a total station (TS)+a target on the machine', is used to confirm the planned course. However, unavoidable curved sections are present in small-sized pipe lines, which are laid after implementation of a road system, for public works such as waterworks, sewer, electrical power, and gas and communication networks. Therefore, if the planned course has a curved section, it is difficult to survey the course with the abovementioned simple composition. This difficulty could be solved by using the multiple total stations (MTS), which attaches the cross type linear LED target to oneself. The MTS are disposed to where each TS can detect the LED target at the other TS or the base point or the machine. And the accurate relative positions between each MTS and target are calculated from measured data. This research proposes the relative and absolute coordinate calculation algorithm by using three MTS to measure a curved course with 20m curvature at 30m maximum distance, and verifies the algorithm experimentally.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.58_59
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• 2009

Generator excitation system, supplying the voltage to power system, is controlled by various manners as aspects of power system. Previously excitation systems mainly used AVR(Automatic Voltage Regulator) and FCR(Field Current Regulator) to control voltage, but nowadays the excitation systems have the tendency to adopt AQR(Automatic Reactive power Regulator) and APFR(Automatic Power Factor Regulator) to do it so as to get into step with diverse requirements of power system and high digital technology. This paper presents which operation methods is effective for the equipment, according to increase the unmanned power station thanks to automation technic.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1302-1308
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• 2007

In this paper, a real-time collision avoidance algorithm is proposed for experimental Autonomous Vehicle(XAV). To ensure real-time implementation, a virtual potential field is calculated in one dimensional space. The attractive force is generated by the steering command either transmitted in the remote control station or calculated in the Autonomous Navigation System(ANS) of the XAV. The repulsive force is generated by obstacle information obtained from Laser Range Finder(LRF) mounted on the XAV. Using these attractive and repulsive forces, modified steering, velocity and emergency stop commands are created to avoid obstacles and follow a planned path. The suggested algorithm is inserted as one component in the XAV system. Through various real experiments and technical demonstration using the XAV, the usefulness and practicality of the proposed algorithm are verified.

• Industrial Engineering and Management Systems
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• v.6 no.2
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• pp.125-135
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• 2007

An automated guided vehicle (AGV) system is a group of collaborating unmanned vehicles which is commonly used for transporting materials within manufacturing, warehousing, or distribution systems. The performance of an AGV system depends on the dispatching rules used to assign vehicles to pickup requests, the vehicle routing protocols, and the home location of idle vehicles, which are called dwell points. In manufacturing and distribution environments which emphasize just-in-time principles, performance measures for material handling are based on response times for pickup requests and equipment utilization. In an AGV system, the response time for a pickup request is the time that it takes for the vehicle to travel from its dwell point to the pickup station. In this article, an exact dynamic programming algorithm for selecting dwell points in a tandem-loop multiple-vehicle AGV system is presented. The objective of the model is to minimize the maximum response time for all pickup requests in a given shift. The recursive algorithm considers time restrictions on the availability of vehicles during the shift.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.35-36
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• 2015

무인항공기는 광대역의 전장 정보를 실시간으로 획득하거나 적 위협정보를 파악하기 위해 영상정보를 활용하며 보다 정확한 감시 및 정찰 정보의 획득과 가시화를 위해 정밀한 영상정보처리 기법이 요구된다. 이를 위해 본 논문에서는 무인항공기를 통해 획득한 영상 정보를 지상통제장비로 전송하고 이를 효과적으로 시각화하는 통합 시스템을 제안한다. 제안하는 영상정보처리 시각화 시스템을 통해 무인항공기와 지상통제장비는 전장에서 요구되는 임무와 역할을 효과적으로 수행할 것으로 기대한다.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.109.5-109
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• 2002

Autonomous underwater vehicles (AUVs) are unmanned underwater vessels to investigate sea environments, oceanography and deep-sea resources autonomously. Docking systems are required to increase the capability of the AUVs to recharge the batteries and to transmit data in real time in underwater. This paper presents a visual servo control system for an AUV to dock into an underwater station with a camera. To make the visual servo control system , this paper derives an optical flow model of a camera mounted on an AUV, where a CCD camera is installed at the nose center of the AUV to monitor the docking condition. This paper combines the optical flow equation of the camera with the AUV's equation o...

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.735-741
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• 2005

We have studied the prearranged plan and the economy of a candidate site for the development of small hydro power. And also we have confirmed its economy by suggesting the technology of the unmanned operation and the selection of the water turbine generator which has a great efficiency, working rate and suitability to the topographical characteristics of various development sites, for example, irrigation reservoirs, water works pipes, sewage systems and cooling water of a steam power station. We proposed some opinions such as the better improvement of small hydropower industry the people' view, cooperation among industry/university/ research institutes, remote control/maintenance and goverment's legislature and supporting system etc.