• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.941-944
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• 2007

본 연구에서는 센서 네트웍과 컴퓨터 비전 시스템을 이용한 모바일 센서 네트워크(Mobile Sensor Network) 의 응용에 관한 실험을 수행하였다. 주된 내용으로는 모바일 센서를 탑재한 차량을 이용한 로컬라이제이션(Localization) 과 팀원 인식(Team Identification) 등에 관련된 방법을 포함한다. 본 시스템은 시뮬레이션을 통하여 기획을 하였으며 자체 설계한 하드웨어와 내장형 소프트웨어를 탑재하여 주어진 기능을 수행하도록 하도록 하는 한편, 모바일 센서의 역할을 할 수 있도록 다양한 센서를 장착할 수 있도록 설계되었다. 또한 전자나침반을 이용한 방위각 측정능력, 초음파 센서를 이용한 근거리 장애물 회피 능력, 적외선 발광 다이오드(IR-LED)와 적외선 필터를 씌운 카메라를 이용한 동료의 위치 파악 능력등을 통하여 로컬라이제이션에 도움이 되도록 한다. 통신을 위하여 IEEE 802.11g 프로토콜에 기반을 둔 통신 능력을 가지며 차량간의 통신도 같은 프로토콜을 통하여 이루어지게 된다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.155-163
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• 2013

The ancient sailing routes between Silla Korea and Tang China have been a hot issue among the researchers. Some assert that the Korean seafarers under Chang Po-go sailed the East China Sea directly from China to the Korean Peninsula with the assistance of mariner's compass on boarding V-shaped vessels in the 9th century. As we all know, Chinese used the mariner's compass in the 11th century and Europeans in the 12th century. In this paper, the author analyzed the maritime meteorological condition for sailing ships to navigate in the East China Sea and retraced the rafting route by Yun in 1997. As the results of analysis, the author confirmed that the maritime meteorological condition might be favorable for the seafarers to be capable of navigating in the East China Sea from China to Korea in June and July. But even the sea condition might be favorable, it must be God's will for the ancient seafarers to reach the Korean Peninsula. On Yun's rafting account, the author found out that there is a difference between the sailing route drawn by Yun himself and the actual drifted route and the raft drifted at 1.7~2.0 knots. This was quite an extraordinary speed considering the unfavorable sea condition and raft itself without keel. In conclusion, the author reaffirms that it was after the year 1068 for the seafarers to navigate in the East China Sea directly from China to Korea without any historical proofs or evidences.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.37-40
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• 2007

Digital Magnetic Compass(DMC)는 실내의 전자기적 요소나 강한 자성체 건물구조에서는 쉽게 방해를 받던 Compass보다 실내에서 간섭에 강한 특징을 가지고 있다. 그리고 적외선 센서와 초음파 센서는 서로 물체와의 거리를 보완적으로 계산해 줄뿐만 아니라 값싼 센서로서 경제적인 이점을 가지고 있어 Simultaneous Localization and Mapping(SLAM)에서 많이 사용하고 있다. 본 논문에서는 자율 이동 로봇의 구동에서 Digital Magnetic Compass(DMC)와 Ultrasonic Sensors을 이용한 SLAM의 구현에 대해 연구하였다. 로봇의 특성상 한정된 Sensing 데이터만으로 방향과 위치를 파악하고 그 데이터 값으로 가능한 빠르게 Localization을 하여야 한다. 그러므로 자율 이동 로봇에서의 SLAM 적용함으로 Localization 구현과 Mapping을 수행하고 SLAM 구현상의 주된 연구 중의 하나인 Kid Napping 문제에 중점을 두고 연구한다. 특히, Localization 구현을 수행을 위한 데이터의 Sensing 방법으로 적외선 센서와 초음파 센서를 같이 사용하였고 비슷한 위치의 데이터 값이 주어지거나 사전 정보 없는 상태에서는 로봇의 상태를 파악하기 위해서 DMC을 같이 사용하여 더 정확한 위치를 측정에 활용하였다.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.1
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• pp.50-57
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• 2008

The anatomy which is the systemic understanding of a structure and the physical examinations which is the functional assessment of its role comprise the fundamental capability for a clinician providing medial care to the knee. This article provides the basic anatomy of the bones, meniscus, anterior and posterior cruciate ligaments, medial and lateral collateral ligaments, muscles, medial and lateral 3 layer concept, anterior and posterior aspect of the knee, bursae around the knee, and the physical examinations of the meniscus, medial and lateral collateral ligament, anterior and posterior cruciate ligament with posterolateral corner. The conceptual and systemic understanding of the anatomy and the physical examinations of the knee would be a compass or lighthouse for the physician providing medical care to the knee.

• Convergence Security Journal
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• v.11 no.6
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• pp.17-23
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• 2011

In this paper, we propose mobile Augmented Reality(AR) for smart learning system which is advanced e-learning. AR is technology that seamlessly overlays computer graphics on the real world. AR has become widely available because of mobile AR. Mobile AR is possible to get information from real world anytime, anywhere. Nowadays, there are various areas using AR such as entertainment, marketing, location-based AR. One of the most promising areas is education. AR in education shows lifelike images to users for realism. It's a good way for improving concentration and attention. We utilize only a camera for image-based AR without other sensor.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.418-423
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• 2003

This paper describes an electronic compass using micromachined X- and Y-axis micro fluxgate sensors which were perpendicularly aligned each other to measure X- and Y-axis magnetic fields respectively. The fluxgate sensor was composed of rectangular-ring shaped magnetic core and solenoid excitation(49 turns) and pick-up(46 turns) coils. Excitation and pick-up coil patterns which were formed opposite to each other wound the magnetic core alternatively to improve the sensitivity and to excite the magnetic core in an optimal condition with reduced excitation current. The magnetic core has DC effective permeability of ~1000 and coercive field of ~0.1 Oe. The magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. To decrease the difference of induced second harmonic voltages from X- and Y-axis, excitation condition of 2.8 $V_{P-P}$ and 1.2 MHz square wave was selected. Excellent linear response over the range of -100 $\mu$T to +100 $\mu$T was obtained with 210 V/T sensitivity. The size of each micro fluxgate sensor excluding pad region was about 2.6${\times}$1.7 $mm^2$ and the power consumption was estimated to be 14 mW.W.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1057-1064
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• 2017

High sensitivity magnetic sensor having foreign metal detection capability is proposed utilizing giant magneto-impedance effect. Strip sensor showed the increasing output voltage when the external magnetic field was applied along with strip from strip grounding point, although the initial DC voltage varied depending on the pointing direction of strip sensor. Proposed sensor was able to eliminate more than half of background noise using active noise filter to achive high sensitivity, and it showed the capability to detect magnetized foreign metal object independent of ambient electro-magnetic noise and earth magnet. In case of ferrous sphere, the metal detection up to 0.8mm diameter was experimentally demonstrated at 5mm distance from strip sensor.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.111-118
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• 2010

The proposed algorithm to be explained in this paper is the localization technique using directional antenna. Here, it is assumed that anchor node has the ability to transfer the azimuth of each sector using GPS modules, sector antenna, and the digital compass. In the conventional sensor network, the majority of localization algorithms were capable of estimating the position information of the sensor node by knowing at least 3 position values of anchor nodes. However, this paper has proposed localization algorithm that estimates the position of nodes to continuously move with sensor nodes and traveling nodes. The proposed localization mechanisms have been simulated in the Matlab. The simulation results show that our scheme performed better than other mechanisms (e.g. MCL, DV-distance).

• Journal of the Korean earth science society
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• v.35 no.7
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• pp.585-597
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• 2014

This study surveys how teachers can improve their understanding about the concept of declination only through reading the material presented as non-dipole magnetic model. This study also investigates a difference between the content of declination presented in "Earth Science II" textbook under the 2009 revised National Curriculum and that of the past one. Thirty teachers in Gyeonggi province and thirty three in the city of Seoul are surveyed; they are selected from the participants of required training that provides their first grade regular teaching certification. Findings of this study are as follows. First, the study finds that teacher participants possess several misconceptions about the declination. Their typical misconception show that a compass needle directly indicates the magnetic north pole. This type of misconception is not corrected only by a reading the material. Second, the study shows that the degree of teachers' understanding about the concept of declination improves through the reading the material of a non-dipole magnetic model. Third, the study reveals that the material of nod-dipole magnetic model is more effective with teachers than students. Finally, the study suggests that explanations including non-dipole magnetic model be revised in the current textbooks.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.8-15
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• 2011

This paper proposes a real-time navigation algorithm which integrates the artificial potential field (APF) for an unmanned vehicle in the unknown environment. This approach uses repulsive potential function around the obstacles to force the vehicle away and an attractive potential function around the goal to attract the vehicle. In this research, laser range finder is used as range sensor. An obstacle detected by the sensor creates repulsive vector. Differential global positioning system (DGPS) and digital compass are used to measure the current vehicle position and orientation. The measured vehicle position is also used to create attractive vector. This paper proposes a new concept of potential field based navigation which controls unmanned vehicle's speed and steering. The magnitude of repulsive force based on the proposed algorithm is designed not to be over the magnitude of attractive force while the magnitude is increased linearly as being closer to obstacle. Consequently, the vehicle experiences a generalized force toward the negative gradient of the total potential. This force drives the vehicle downhill towards its goal configuration until the vehicle reaches minimum potential and it stops. The effectiveness of the proposed APF for unmanned vehicle is verified through simulation and experiment.