• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.219-222
• /
• 2004

There are several factors that disturb an Ultra-Wideband (UWB) radio propagation in an indoor environment such as path loss, shadowing and multipath fading. These factors directly affect the quality of the received signal. In this paper, we investigated the influence of the human body shadowing on UWB propagation based on measured wireless channel in an anechoic chamber. The characteristics of the UWB channel including the transmitter and the receiver antenna effects are acquired over the frequency bandwidth of 3${\sim}$11 GHz. The major factors such as the power delay profile (PDP), the angular power distribution (APD), the pulse distortion and the RMS delay spread caused by the human body shadowing are presented.

• IEIE Transactions on Smart Processing and Computing
• /
• v.6 no.2
• /
• pp.133-139
• /
• 2017

Vehicles have increasingly evolved and become intelligent with convergence of information and communications technologies (ICT). Vehicle communications (VC) has become one of the major necessities for intelligent vehicles. However, VC suffers from serious security problems that hinder its commercialization. Hence, the IEEE 1609 Wireless Access Vehicular Environment (WAVE) protocol defines a security service for VC. This service includes Advanced Encryption Standard-Counter with CBC-MAC (AES-CCM) for data encryption in VC. A high-speed AES-CCM crypto module is necessary, because VC requires a fast communication rate between vehicles. In this study, we propose and implement an efficient AES-CCM hardware architecture for high-speed VC. First, we propose a 32-bit substitution table (S_Box) to reduce the AES module latency. Second, we employ key box register files to save key expansion results. Third, we save the input and processed data to internal register files for secure encryption and to secure data from external attacks. Finally, we design a parallel architecture for both cipher block chaining message authentication code (CBC-MAC) and the counter module in AES-CCM to improve performance. For implementation of the field programmable gate array (FPGA) hardware, we use a Xilinx Virtex-5 FPGA chip. The entire operation of the AES-CCM module is validated by timing simulations in Xilinx ISE at a speed of 166.2 MHz.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.4
• /
• pp.379-384
• /
• 2002

This paper represents the mobile robot system remote controlled by PDA(personal digital assistance). So far, owing to the development of internet technologies, lots of remote control methods through internet have been proposed. To control a mobile robot through internet and guide it under unknown environment, We propose a control method activated by PDA. In a proposed system, PDA acts as a user interface to communicate with notebook as a controller of the mobile robot system using TCP/IP protocol, and the notebook controls the mobile robot system. The information about the direction and velocity of the mobile robot feedbacks to the PDA and the PDA send new control method produced from the fuzzy inference engine.

• Convergence Security Journal
• /
• v.3 no.3
• /
• pp.25-33
• /
• 2003

With the radical improvement of wire and wireless communication technologies, home network which interconnects various home appliances is approaching ripening stage. Digitalization of the home environment will break down the boundaries of information, communications and broadcasting, and enable us to realize many breakthroughs on the home front and connect to our home. In order to enable users to access securely to their home network, we first construct secure home network model which can authorize users using their permission policy. In this paper, we examine various security technique used in home network and propose home network security scheme which can service constantly.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.4
• /
• pp.923-948
• /
• 2013

The main concern in mobile peer-to-peer (P2P) networks is security because jamming or eavesdropping on a wireless link is much easier than on a wired one and such damage can be incurred without physical access or contact. In particular, authentication has increasingly become a requirement in mobile P2P environments. This paper presents a new mutual authentication mechanism which requires less storage space and maintains a high level of security in mobile P2P networks. The proposed mechanism improves efficiency by avoiding the use of centralized entities and is designed to be agile in terms of both reliability and low-cost implementation. The mechanism suggested in the simulation evaluates the function costs occurring in authentication between the devices under mobile P2P network environment comparing to existing method in terms of basic operation costs, traffic costs, communications costs, storage costs and scalability. The simulation results show that the proposed mechanism provides high authentication with low cryptography processing overhead.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.8
• /
• pp.73-82
• /
• 2004

In this paper, implementation of obstacle avoidance of a nonholonomic mobile robot in unstructured environment is introduced. To avoid obstacles, first, a reference collision-free path for the MR is generated off-line using HJB-based optimal path planning method. A controller is designed using integrator backstepping method for tracking the generated reference path. To implement the designed controller, a control system are needed and composed of camera system and PIC-based controller. The workspace is observed by a ceiling-mounted USB camera as part of an un-calibrated camera system. Thus the positional information of the MR is updated frequently and the MR can get the useful inputs for its tracking controller. The whole control system is realized by integrating a computer with PIC-based microprocessor using wireless communication: the image processing control module and path planning module serve as high level computer control while the device control serves as low level PIC microprocessor control. The simulation and experimental results show the effectiveness of the designed control system.

• Journal of Korea Multimedia Society
• /
• v.6 no.7
• /
• pp.1231-1238
• /
• 2003

As the demand on multicast services increases to support the terminal mobility in the midst of the development of wireless mobile communication technology, many new methods have been studied. However, previous methods occur delay and packet loss during re-joining to multicast service group when moving mobile node. In this paper, we will propose a scheme that decreases packet loss using regional registration method. Proposed scheme modified signaling message of previous regional-registration and added caching. In case move to same GFA, we can prevent packet loss by keeping registration to FA until perfectly registration ends. Also, In case move to other GFA, we can reduce packet loss by using cache. Therefore, we can receive efficient multicast service.

• Journal of Intelligence and Information Systems
• /
• v.11 no.1
• /
• pp.53-63
• /
• 2005

Adaptive services need to become as mobile as their users and be extended to take advantage of the constantly changing context in which they are accessed. Context-awareness is a technology to facilitate information acquisition and execution by supporting interoperability between users and devices based on users' context. The objective of this study is to develop a middleware fer dealing with context-awareness in ubiquitous computing. To achieve it, our middleware plays an important role in recognizing a moving node with mobility by using a bluetooth wireless communication technology as well as in executing an appropriate execution module according to the context acquired from a context server. In addition, for verifying the usefulness of the Proposed middleware, we develop an application system which Provides a music playing service based on context information by using our context middleware.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.1
• /
• pp.64-69
• /
• 2008

In order that a mobile robot can perform tasks in unknown environment localization of a mobile robot is essential task. In this paper, a new localization method for a mobile robot using an active landmark is proposed, which is very simple to implement. The landmark has a LED which can be controlled by a mobile robot via wireless communication. CCD camera gets two images of the landmark, one of which is with LED off and the other is with LED on. Because the landmark can be detected by using the difference image of the two images, detection time can be minimized. By using the characteristic points of the landmark, localization can be performed simply. A series of experiments are performed to evaluate the proposed method and the experimental results show that the proposed method can be applicable to the localization of a mobile robot.

• Journal of Satellite, Information and Communications
• /
• v.12 no.4
• /
• pp.26-33
• /
• 2017

A drone performs a mission through remote control or automatic control, which uses wireless communications technology. Recently the increasing use of drones, the drone signal RF detection is necessary. In this paper, we propose an efficient dron RF detection method through simulations considering Wi-Fi, Bluetooth and dedicated protocol dron communication method in ISM(Industry Science Medical) band.. After configuring an environment where a common terminal and a drone signal are mixed, a general terminal and a drone signal are distinguished from each other by using a RF characteristic according to a dron movement. The proposed drone RF detection method is the WRMD(Windowed RSSI Moving Detection) operation and the Doppler frequency identification method. The simulation environments consist to mixed for two signals and four signals. We analysis the performance to proposed drone RF detection technique thorough detection rate.