• Journal of the Korean Geographical Society
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• v.32 no.2
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• pp.197-215
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• 1997

The purpose of this study is to show practices of teaching method based on the type of knowledge in geography education. The results of examining the type of knowledge according to the five themes in guidelines for geographic education in america are as follows: the empirical-analytic knowledge-centered contents are suited for designing concepts inquiry-centered teaching. The historical-hermeneutic knowledge-centered contents are suited for designing problem solving-centered teaching. The critical knowledge-centered contents are suited for designing decision-making-centered teaching. In this shsdy, 1 emphasized teaching method based on the type of knowledge in Ceographv Education according to the responses of students and academic achievement. However, in practice l propose that teachers construct their lesson plans according to their various spheres of interest.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.1
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• pp.67-75
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• 2010

This paper presents localization algorithm for mobile robot in outdoor environment. Outdoor environment includes the uncertainty on the ground. Magnetic sensor or IMU(Inertial Measurement Unit) has been used to estimate robot's heading angle. Two sensor is unavailable because mobile robot is electric car affected by magnetic field. Heading angle estimation algorithm for mobile robot is implemented using gyro sensor module consisting of 1-axis gyro sensors. Localization algorithm applied Extended Kalman filter that utilized GPS and encoder, gyro sensor module. Experiment results show that proposed localization algorithm improve considerably localization performance of mobile robots.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.31-40
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• 2017

Absolute nodal coordinate formulation was developed in the mid-1990s, and is used in the flexible dynamic analysis. In the process of deriving the equation of motion, if the order of polynomial referring to the displacement field increases, then the degrees of freedom increase, as well as the analysis time increases. Therefore, in this study, the primary objective was to reduce the analysis time by transforming the dimensional equation of motion to a non-dimensional equation of motion. After the shape function was rearranged to be non-dimensional and the nodal coordinate was rearranged to be in length dimension, the non-dimensional mass matrix, stiffness matrix, and conservative force was derived from the non-dimensional variables. The verification and efficiency of this non-dimensional equation of motion was performed using two examples; cantilever beam which has the exact solution about static deflection and flexible pendulum.

• Ecology and Resilient Infrastructure
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• v.2 no.1
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• pp.54-63
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• 2015

This study was conducted to investigate the flora and vegetation structure at a 15-year-old artificial wetland for the water purification in Jincheon, Korea. The percentage of species number of obligate wetland plants and facultative wetland plants totaled 40%, whereas that of obligate upland plants and facultative upland plants was 57%. This result showed that the artificial wetland in the study experienced terrestrialization. The number of annual and biennial plants that are pioneer vegetation in a successional stage was lower than that of perennial herbs as a result of the long-term stabilization of vegetation. From the results of DCA (detrended correspondence analysis), water depth played an important role on the classification of vegetation structure in an old artificial wetland. Species diversity was higher in the terrestrialized plant communities such as Iris pseudacorus and Aster koraiensis than in any other wetland communities. Plant communities could be classified according to the wetland indices; obligate upland for A. koraiensis community, facultative wetlands for Carex dispalata var. dispalata and I. pseudacorus community, and obligate wetlands for Nymphoides peltata, Nymphaea tetragona, Phragmites communis, Potamogeton maackianus, and Typha angustifolia community. In conclusion, this result suggests that wetland vegetation should be maintained against terrestrialization through the proper management of sedimentation and hydrological regime in an artificial wetland.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.2
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• pp.27-32
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• 2004

Absolute optical angle sensor is described that is an essentially digital opto-electronic device. Its purpose is to resolve the relative and absolute angle position of coded disk using Pseudorandom-code and Geometry-code. In this technique, the angular position of disk is determined in coarse sense first by Pseudorandom-code. A further fine angular position data based on Pixel count is obtained by Geometry-code which result 0.006$^{\circ}$ resolution of the system provided that 7 ${\mu}{\textrm}{m}$ line image sensor are used. The proposed technique is novel in a number of aspects, such that it has the non-contact reflective nature, high resolution of the system, relatively simple code pattern, and inherent digital nature of the sensor. And what is more the system can be easily modified to torque sensor by applying two coded disks in a manner that observe the difference in absolute angular displacement. The digital opto-electronic nature of the proposed sensor, along with its reporting of both torque and angle, makes the system ideal for use in intelligent vehicle systems. In this communication, we propose a technique that utilizes Pseudorandom-code and Geometry-code to determine accurate angular position of coded disk. We present the experimental results to demonstrate the validity of the idea.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.227-240
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• 1999

We performed CCD photometric observations of W UMa type contact binary BV Dra during eight nights from May 1996 to June 1999 using 61cm telescope at Sobaeksan Optical Astronomy Observatory, and completed BV R light curves of the system. From our observations, we derived nine new times of minimum lights (five timings for primary eclipse, four for secondary) and determined new light elements with the times of minima observed since 1999. Our BV R light curves and Batten & Lu(1986)'s radial-velocity ones were simultaneously analyzed with contact mode (Mode 3) of Wilson-Devinney's binary model, and the photometric and spectroscopic solutions for BV Dra were solved. In the analysis, we derived the solutions of 1999 light curves with and without spots, respectively. As the results, asymmetry of light curves may be interpreted as produced by the existence of two spots; hot spot on the secondary and cool on the primary. Combining solutions of light curves and radial-velocity ones, absolute dimensions of BV Dra are $M_1=0.40M_{odot}$, $M_2=1.01M_{odot}$, $R_1=0.72R_{odot}$, $R_2=0.40R_{odot}$. In mass-radius diagram, the less massive and hotter primary component of BV Dra is near TAMS and the secondary is near ZAMS, which is very similar to the other W-type W UMa binaries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2123-2130
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• 2015

For such automatic monitoring robot or a robot cleaner that is utilized indoors, if it deviates from someone by replacement or, or of a mobile robot such as collisions with unexpected object direction or planned path, based on the planned path There is a need to come back to, it is necessary to tough self-position estimation ability of mobile robot in this, which is also associated with resolution of the kidnap problem of conventional mobile robot. In this study, the case of a mobile robot, operates indoors, you want to take advantage of the low cost of the robot. Therefore, in this paper, by using the acquisition device to an external image information such as the CCTV which is installed in a room, it acquires the environment image and take advantage of marker recognition of the mobile robot at the same time and converted it absolutely spatial coordinates it is, we are trying to solve the self-position estimation of the mobile robot in the room and kidnap problem and actual implementation methods potential field to try utilizing robotic systems. Thus, by implementing the method proposed in this study to the actual robot system, and is promoting the relevant experiment was to verify the results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.3
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• pp.305-315
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• 2010

This research aims to develop a method to determine the 3D coordinates of an object point from overlapping omni-directional images acquired by a ground mobile mapping system and assess their accuracies. In the proposed method, we first define an individual coordinate system on each sensor and the object space and determine the geometric relationships between the systems. Based on these systems and their relationships, we derive a straight line of the corresponding object point candidates for a point of an omni-directional image, and determine the 3D coordinates of the object point by intersecting a pair of straight lines derived from a pair of matched points. We have compared the object coordinates determined through the proposed method with those measured by GPS and a total station for the accuracy assessment and analysis. According to the experimental results, with the appropriate length of baseline and mutual positions between cameras and objects, we can determine the relative coordinates of the object point with the accuracy of several centimeters. The accuracy of the absolute coordinates is ranged from several centimeters to 1 m due to systematic errors. In the future, we plan to improve the accuracy of absolute coordinates by determining more precisely the relationship between the camera and GPS/INS coordinates and performing the calibration of the omni-directional camera

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.99-110
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• 2009

The main purpose of the current research is to developments a real-time Hardware In-the-Loop (HIL) simulation testbed for the satellite formation flying navigation and orbit control. The HIL simulation testbed is integrated for demonstrations and evaluations of navigation and orbit control algorithms. The HIL simulation testbed is composed of Environment computer, GPS simulator, Flight computer and Visualization computer system. GPS measurements are generated by a SPIRENT GSS6560 multi-channel RF simulator to produce pseudorange, carrier phase measurements. The measurement date are transferred to Satrec Intiative space borne GPS receiver and exchanged by the flight computer system and subsequently processed in a navigation filter to generate relative or absolute state estimates. These results are fed into control algorithm to generate orbit controls required to maintain the formation. These maneuvers are informed to environment computer system to build a close simulation loop. In this paper, the overall design of the HIL simulation testbed for the satellite formation flying navigation and control is presented. Each component of the testbed is then described. Finally, a LEO formation navigation and control simulation is demonstrated by using virtual scenario.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.588-594
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• 2015

Although GPS technology for location positioning system has been widely used, it is difficult to be used in intelligent transport systems, due to the large positioning error and limited area for receiving radio signals. Thanks to the rapid development of LED technology, LED lights become popular in many applications. Especially, visible light communications (VLC) has raised a lot of interests because of the simultaneous functioning of LED illumination and communication. Recent studies on positioning system using VLC mainly focused on indoor environments and still difficult to satisfy positioning accuracy and simple implementation simultaneously. In this paper, we propose a positioning system based on VLC using the coordinate information of LEDs installed on the road infrastructure. Extracting the LED signal, obtained through VLC, from the easily accessible camera image, it is possible to estimate the position of the car on the road. Simulation results show that the proposed scheme can achieve a high positioning accuracy of 1 m when large number of pixels is utilized and the distance from the LED light is close.