• The KIPS Transactions:PartA
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• v.12A no.1 s.91
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• pp.23-30
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• 2005

Causal order of message delivery algorithm ensures that every transmitted message is delivered in causal order. It should be noted that control information should be transmitted with each message in order to enforce causal order. Hence, it is important to reduce this communication overhead because the impact of the overhead increases proportionally with the number of related processes. In this paper we propose and evaluate effective a ${\Delta}-causal$ order algorithm for multimedia data which have real-time property. To reduce transmission overhead, proposed algorithm eliminates redundant information as early as possible which is not explicitly required for preserving causal order. Average communication overhead of our algorithm is much smaller than other existing algorithms.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.339-342
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• 2005

In order to support ultrawide-band signal generation for low rate WPAN, several types of signal generation mechanisms are suggested such as Chaos, Impluse, and Chirp signals by the activity of IEEE 802.15.4a. The communication system applied chaos theory may have ultrawide-band characteristics with spread spectrum and immunity from multipath effect. In order to use the advantage of chaotic signal generation, we introduce the system implementation of communication and networking systems with the chaos UWB signal. This system may be composed of mainly three parts in hardware architecture : RF transmission with chaotic signal generation, signal receiver using amplifiers and filters, and 8051 & FPGA unit. The most difficult part is to implement the chaotic signal generator and build transceiver with it. The implementation of the system is devidced into two parts i.e. RF blocks and digital blocks with amplifiers, filters, ADC, 8051 processor, and FPGA. In this paper, we introduce the system block diagram for chaotic communications. Mainly the RF block is important for the system to have good performance based on the chaotic signal generator. And the main control board functions for controlling RF blocks, processing Tx and Rx data, and networking in MAC layer.

• The KIPS Transactions:PartD
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• v.9D no.5
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• pp.931-938
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• 2002

We implement the PBSM (Protocol-Based Security Module) system which guarantees the secure data transmission under web circumstances. There are two modules to implement for the PBSM architecture. One is Web Server Security Module (WSSM) which is working on a web server, the other is the Winsock Client Security Module (WSCSM) which is working on a client. The WSCSM security module decrypts the encrypted HTML document that is received from the security web server The decrypted HTML document is displayed on the screen of a client. The WSSM module contains the encryption part for HTML file and the decryption part for CGI (Common Gateway Interface). We also implement the proposed idea at the web system.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.383-388
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• 2007

In this paper, we propose a new signal frame structure based on Alamouti code that can maintain the same performance as Alamouti code and increase spectral efficiency. The proposed signal frame structure can increase spectrum efficiency to approach 1(bit/s/Hz) since it can process n bit data during (n+1) time slot. In order to verify two performances, we derive closed form BER via mathematical approach, and compare with the simulation result in Rayleigh fading plus AWGN channel. Then we find that the two performances are exactly same.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.177-184
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• 2006

A handover is a technology that enables data transmission and receipt seamlessly while a mobile station moves from the current base station to another base station. The handover is basically classified into two types; a horizontal handover which changes a radio link only without changing a network link, and a vertical handover which changes both in heterogeneous networks. In this paper, we propose a vertical handover protocol in a dual base station which supports both of W-CDMA and WiBro networks based on SDR (Software Defined Radio), verify the rightness using a state transition diagram and a Petri-net, and evaluate the performance of the proposed protocol using NS-2 simulator.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.178-184
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• 1998

Optical fiber coupler is a crucial optical passive component for optical transmission systems. In this paper, we fabricate wavelength insensitive optical coupler(WIC), of two types for which the processing procedures are complicate and difficult. These couplers are fabricated by two optical fibers having either different fiber parameters or different cladding diameters. To clarify the validity, we measure the optical characteritics and compare to the data of theoretical simulation. The experiment results ref#eat that it has uniformity of about 1.0 dB and excess loss of less than 0.1 dB in the range of $1310{\pm}40nm\;and\;1550{\pm}40nm$.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.225-232
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• 1998

Currently NTSC, PAL, and SECOM are widely used for TV broadcasting systems. In Korea, NTSC has been used to reduce transmission bandwidth and broadband flickers using the Interlaced scanning method. Image data in the Interlaced scanning method require De-interlacing compensation for PC-based multimedia applications. The existing compensation algorithms such as ZOI, FOI, and ELA provieds simple computations and effective image compensation while the PSNR is low and horizontal and vertical edges are hardly detected. In this paper, the ADI(Adaptive De-Interlacing) algorithm that can increase PSNR and detect horizontal and vertical edges is proposed and a hardware system is implemented using three ACTEL 1020B FPGA chips. The system consists of the algorithm part implemented using two FPGAs and the memory control part implemented using rest one. Also the system operation is investigated for real time processing.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.955-963
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• 2008

In this paper, we propose an improved practical encryption and fault-tolerance decryption method using a non-negative value key and random function obtained with a white noise by using iterative phase wrapping method. A phase wrapping operating key, which is generated by the product of arbitrary random phase images and an original phase image. is zero-padded and Fourier transformed. Fourier operating key is then obtained by taking the real-valued data from this Fourier transformed image. Also the random phase wrapping operating key is made from these arbitrary random phase images and the same iterative phase wrapping method. We obtain a Fourier random operating key through the same method in the encryption process. For practical transmission of encryption and decryption keys via Internet, these keys should be intensity maps with non-negative values. The encryption key and the decryption key to meet this requirement are generated by the addition of the absolute of its minimum value to each of Fourier keys, respectively. The decryption based on 2-f setup with spatial filter is simply performed by the inverse Fourier transform of the multiplication between the encryption key and the decryption key and also can be used as a current spatial light modulator technology by phase encoding of the non-negative values. Computer simulations show the validity of the encryption method and the robust decryption system in the proposed technique.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.3
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• pp.29-36
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• 2005

With the rapid growth of the Internet, the Internet-based robot has been realized by connecting off-line robot to the Internet. However, because the Internet is often irregular and unreliable, the varying time delay in data transmission is a significant problem for the construction of the Internet-based robot system. Thus, this paper is concerned with the development of an Internet-based robot system, which is insensitive to the Internet time delay. For this purpose, the PPS (Position Prediction Simulator) is suggested and implemented on the system. The PPS consists of two parts : the robot position prediction part and the projective virtual scene part. In the robot position prediction part, the robot position is predicted for more accurate operation of the mobile robot, based on the time at which the user's command reaches the robot system. The projective virtual scene part shows the 3D visual information of a remote site, which is obtained through image processing and position prediction. For the verification of this proposed PPS, the robot was moved to follow the planned path under the various network traffic conditions. The simulation and experimental results showed that the path error of the robot motion could be reduced using the developed PPS.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.7
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• pp.17-27
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• 2011

In recent years, the interest and research for Future Internet are rapidly increasing. In domestic, MOFI (Mobile Oriented Future Internet) is proposed as one architecture of Future Internet. MOFI is a data transmission architecture which provides a mobility, name-based communication and routing scalability. In this paper we implement a basic MOFI testbed that supports HID-based communication, and verify the feasibility of HID-based communication through experimentation of general service such as PING and WWW service. We used "VirtualBox" as a virtual machine and implement a packet processing and a HCP header addition and translation function using "Click Modular Router".