• Journal of Information Processing Systems
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• 제12권2호
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• pp.263-274
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• 2016

The exceptional development of electronic device technology, the miniaturization of mobile devices, and the development of telecommunication technology has made it possible to monitor human biometric data anywhere and anytime by using different types of wearable or embedded sensors. In daily life, mobile devices can collect wireless body area network (WBAN) data, and the co-collected location data is also important for disease analysis. In order to efficiently analyze WBAN data, including location information and support medical analysis services, we propose a geohash-based spatial index method for a location-aware WBAN data monitoring system on the NoSQL database system, which uses an R-tree-based global tree to organize the real-time location data of a patient and a B-tree-based local tree to manage historical data. This type of spatial index method is a support cloud-based location-aware WBAN data monitoring system. In order to evaluate the proposed method, we built a system that can support a JavaScript Object Notation (JSON) and Binary JSON (BSON) document data on mobile gateway devices. The proposed spatial index method can efficiently process location-based queries for medical signal monitoring. In order to evaluate our index method, we simulated a small system on MongoDB with our proposed index method, which is a document-based NoSQL database system, and evaluated its performance.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.883-890
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• 2006

Nowadays, CPS is used widely, especially in cases which need more precise position information, such as car navigation systems and even in the mobile robot for position measuring in the outdoor environment. RTK (Real-Time Kinematics) and DGPS (Differential Global Positioning System) have more precise accuracy than the general-purposed GPS. However can't easily use them because of high prices and large size of equipments. In order fur the mobile robot to obtain precise position information it is important that CPS receiver has portability and low price. In this study, we introduce a new GPS data acquisition system that offers the precise position data using the DGPS mechanism and satisfying low cost and portability. In addition to this, we propose an improved data compensation algorithm that offers more accurate position information to the outdoor mobile robot by compensating the error rate of CPS data measured from the three points with geometrical rotation and distance formula. Proposed method is verified by comparing with the precise real position data obtained by RTK. Proposed method has more than 70% performance enhancement.

• 제어로봇시스템학회논문지
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• 제5권1호
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• pp.105-114
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• 1999

By using the conceptual impedance and the elasticity of a serial chain of spring-damper system, a real-time collision-free trajectory generation algorithm is proposed. The reference points on a trajectory connected by the spring-damper system have a mechanism for self-Position adjustment to avoid a collision by the impedance, and the local adjustment of each reference point is propagated through the elasticity to a real robot at the end of the spring-damper system. As a result, the overall trajectory consisting of the reference points becomes free of collision with environmental obstacles and efficient having the shortest distance as possible. In this process, the reference points connected by the spring-damper system take role of virtual robot as global guidance for a real robot, and a cooperative optimization is carried out by the system of virtual robots. A control algorithm is proposed to implement the impedance for a car-like mobile robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.493-495
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• 2004

In this paper, shows a research in accordance with the design the implementation of the localization system for mobile robot using INS(Inertial Navigation System) and GPS(Global Positioning System). First, a Strapdown Inertial Navigation System : SDINS is designed and implemented for low speed walking robot, by modifying Inertial Navigation System which is widely used for rocket, airplane, ship and so on. In addition, thesis proposes the localization of robot with the method of loosely coupled method by using Kalman Filter with INS/GPS integrated system to utilize assumed position and steed data from GPS.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.630-634
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• 2010

In this paper, we designed and fabricated a multi-band folded monopole antenna for mobile handsets that can be used for multiple services. The proposed antenna, with a small size of $28.060{\times}12.665{\times}5.035mm^3$ can provide sufficient bandwidth to cover the GSM900 (Global System for Mobile Communications: 880-960 MHz), DCS (Digital Cellular System: 1710-1880 MHz), K-PCS (Korea-Personal Communication Service: 1750-1870 MHz), Wibro (2300-2390 MHz) and Bluetooth (2400-2483 MHz) bands.

• 전기전자학회논문지
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• 제15권4호
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• pp.339-344
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• 2011

In this paper, we proposed an internal multi-band monopole antenna for mobile phone that can be used for smart phones. The proposed antenna has a small volume of $38{\times}8.5{\times}5\;mm^3$, ground size is $100{\times}60\;mm^2$, and covers the GSM900 (Global System for Mobile communications : 880-960 MHz), DCS (Digital Communications System : 1710-1880 MHz), K-PCS (Korea-Personal Communications Service : 1750-1870 MHz), US-PCS (US Personal Communications Service : 1850-1990 MHz), Bluetooth (2400-2483 MHz), Wibro (2300-2390 MHz) and WLAN (Wireless Local Area Network : 2400-2483.5 MHz) bands. The measured peak gains of the implemented antenna are 1.15 dBi at 920 MHz, 3.58 dBi at 1795 MHz, 3.46 dBi at 1810 MHz, 2.91 dBi at 1920 MHz, 5.18 dBi at 2345 MHz, 3.37 dBi at 2442 MHz.

• 한국인터넷방송통신학회논문지
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• 제15권6호
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• pp.1-9
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• 2015

최근 스마트 장치 확산과 이러한 장치들을 이용한 다양한 서비스들의 도입으로 모바일 보안 및 스마트 TV 보안에 대한 관심이 증가하고 있다. 스마트폰 사용자들은 클라우드 서비스, 게임, 뱅킹 서비스, 모바일 서비스 등의 다양한 서비스를 사용한다. 하지만 현재의 모바일 보안 솔루션과 스마트 TV 보안은 단순히 악성코드를 탐지하거나 모바일 단말 관리, 자체 보안 시스템을 이용하는 수준에 머무르고 있다. 이에 인증서, 법인 문서, 개인의 신용 카드 번호와 같은 보안에 민감한 정보에 대해 서비스 해킹 및 누설을 방지하는 기술이 필요하다. 이러한 문제를 해결하기 위해서 모바일 가상화, ARM TrustZone, GlobalPlatform, MDM과 같은 다양한 모바일 장치의 보안 기술이 연구되었다. 따라서 본 논문에서는 가상화 TYPE-I 기반의 ARM TrustZone 기술을 이용한 효율적 보안 기술 구현 방법을 제시한다.

• 제어로봇시스템학회논문지
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• 제21권6호
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• pp.571-576
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• 2015

This paper proposes an auto-parking controller for omnidirectional mobile robots. The controller uses the multi-sensor system including ultrasonic sensor and camera. The several ultrasonic sensors of robot detect the distance between robot and each wall of the parking lot. The camera detects the global position of robot by capturing the image of artificial landmarks. To improve the accuracy of position estimation, we applied the extended Kalman filter with adaptive fuzzy controller. Also we developed the fuzzy control system to reduce the settling time of parking. The experimental results are presented to verify the usefulness of the proposed controller.

• 대한임베디드공학회논문지
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• 제4권2호
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• pp.69-78
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• 2009

Localization is a very important technique for the mobile robot to navigate in outdoor environment. In this paper, the development of the sensor fusion algorithm for controlling mobile robots in outdoor environments is presented. The multi-sensorial dead-reckoning subsystem is established based on the optimal filtering by first fusing a heading angle reading data from a magnetic compass, a rate-gyro, and two encoders mounted on the robot wheels, thereby computing the dead-reckoned location. These data and the position data provided by a global sensing system are fused together by means of an extended Kalman filter. The proposed algorithm is proved by simulation studies of controlling a mobile robot controlled by a backstepping controller and a cascaded controller. Performances of each controller are compared.

• 제어로봇시스템학회논문지
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• 제15권3호
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• pp.293-299
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• 2009

This paper discusses an autonomous navigation system for urban environments. For the localization of the robot, EKF (Extended Kalman Filter) algorithm is used with odometry, angle sensor, and DGPS (Differential Global Positioning System) measurement. Especially in an urban environment, DGPS is often blocked by buildings and trees and the resulting inaccurate positioning prevents the robot from safe and reliable navigation. In addition to the global information from DGPS, the local information of the curb on the roadway is used to track a route when the global DGPS information is inaccurate. For this purpose, curb detection algorithm is developed and implemented in the developed navigation algorithm. Four different types of navigation strategies are developed and they are switched to adapt to different localization conditions according to the availability of DGPS and the existence of the curbs on the roadway. The experimental results show that the designed switching strategy improves the navigation performance adapting to the environment conditions.