Byung Ha Ahn

Scalar BPM analyses of TE and TM polarized fields in bent waveguides

We have applied the effective index method to reduce the two-dimensional (2-D) refractive index profile into the 1-D refractive index structure and modified the wave equations to obtain the paraxial wave equations. Then, transverse electric (TE) and transverse magnetic (TM) polarized fields in the curved single-mode planar waveguides are analyzed by using the scalar beam-propagation method (BPM) employing the finite-difference method with a slab structure. The bending loss in bent waveguides is analyzed for optical fields obtained from the BPM and comparisons are made between the loss for the waveguides with various radius of curvature and refractive index difference. The outward shift of the optical field, which is generated at the connection between a straight and a bent waveguide, is obtained from the results of calculation of location of the maximum optical intensity. The transition loss can be reduced by introducing an optimized inward offset at a straight-to-bend junction. The birefringence for TE and TM polarized fields in bent waveguides is calculated from the phase difference of the optical fields. The wavelength shift due to the birefringence of TE and TM polarized fields in bent waveguides is also calculated.

Evolutionary computation and power control for radio resource management in CDMA cellular radio networks

This paper has proposed the distributed power control (PC) algorithms that employ two evolutionary computation (EC) techniques in order to solve linear systems of equations for power update in CDMA cellular radio systems. The proposed algorithms are developed by applying evolutionary computation algorithms with the phenotypic and genotypic views to the CDMA power control problem. The major gain from the applied evolutionary computation algorithms is more rapid optimization on linear systems of equations compared with the simple genetic algorithm (GA). Employing the distributed constrained power control (DCPC) as a basic reference algorithm, we have designed and implemented computational experiments on the DS-CDMA system. The results indicate that the proposed algorithms significantly enhance the optimization and calculation speed of power control. The proposed algorithms are also compared with the bang-bang type algorithm used in the IS-95 and the W-CDMA systems. The results show that the proposed the EC-DCPC phenotypic and GAPC genotypic algorithms also have a high potential advantage for increasing the CDMA cellular radio network capacity and decreasing the mobile terminal power consumption.

Distributed power control using the simultaneous mutation of genetic algorithms in cellular radio systems

This paper has proposed a distributed power control algorithm that uses a stochastic search technique in order to solve linear systems of equations for power update in CDMA cellular radio systems. The proposed algorithm is developed by applying Bremermanns evolutionary computation algorithm to the CDMA power control problem. The major advantage of the applied evolutionary computation algorithm is more rapid optimization on linear systems of equations compared with the simple genetic algorithm (SGA). By employing distributed constrained power control (DCPC) as a reference algorithm, we have designed and implemented computational experiments on the DS-CDMA system. The results indicate that the proposed algorithm significantly enhances the optimization speed of power control. The proposed algorithm is also compared with the bang-bang type algorithm used in the IS-95 and W-CDMA systems. The results show that our proposed algorithm also has the potential to increase the CDMA cellular radio network capacity and decrease the mobile terminal power consumption.

Design and development of a new POD security module chip-set based on the OpenCable specification

We have proposed the OpenCable reference model merged with the smart card interface defined by ISO 7816-3 and have implemented a new conditional access system (CAS) using that interface on the PCMCIA interface. In addition, we have also designed hardware architecture for a point of deployment (POD) security module using the above two interfaces. The designed POD security module has an embedded 32-bit RISC microprocessor which manages applications such as MPEG-2 filter, descrambler, and data encryption standard (DES). We tested this modeled and designed system using a prototype and have obtained satisfactory simulation results.

Microscopic simulation in decision support system for the incident induced traffic management

This paper is a part of a comprehensive study in which a decision support system is developed to facilitate traffic mangers in tackling the post incident traffic flows on the freeway network in Korea. The system employs Cellular Automata, which is a microscopic simulation platform. This paper suggests two additional rules to in the modified version of the conventional model. This has enabled us to model more realistically the dynamic flow parameters in post incident scenario. A comparative study of the proposed model with the conventional and modified models suggests that our model displays more realistic results.

Healthcare information systems using digital signature and synchronized smart cards via the Internet

This research paper presents a new two-way double-type smart card terminal and a new system design and development for a prescription order communication system (POCS) between the hospital and pharmacy, based on the Internet, public-key infrastructure (PKI), and concurrently parallel co-operation with both medical professional and patient smart cards in synchronized status, in order to control security and privacy of patients and manage drug histories. A concurrently parallel co-operation method in synchronized status has been proposed in order to merge the digital signature generated by a medical professional with a patients prescription data. The digital signatures written by the medical professionals (doctors and pharmacists) holding and using their individually master smart cards are applied to all contents of the prescription stored on a patient slave smart card in synchronized status in the two-way double-type terminal. Therefore, digital signatures for all prescriptions stored on the smart card should effectively be used to prevent it being altered, forged, or reused by unauthorized users and being repudiated by medical professionals.

Suboptimal Adaptive Filter for Discrete-Time Linear Stochastic Systems

This paper considers the problem of recursive filtering for linear discrete-time systems with uncertain observation. A new approximate adaptive filter with a parallel structure is herein proposed. It is based on the optimal mean square combination of arbitrary number of correlated estimates which is also derived. The equation for error covariance characterizing the mean-square accuracy of the new filter is derived. In consequence of parallel structure of the filtering equations the parallel computers can be used for their design. It is shown that this filter is very effective for multisensor systems containing different types of sensors. A practical implementation issue to consider this filter is also addressed. Example demonstrates the accuracy and efficiency of the proposed filter.

Smart Card Terminal Systems Using ISO/IEC 7816-3 Interface and 8051 Microprocessor Based on the System-on-Chip

A smart card terminal designed and developed to communicate with smart cards via a single System-on-Chip (SoC) is described in this paper. This proposed and developed SoC-based smart card terminal, designed with the Verilog Hardware Description Language (HDL) and the Simulation Program with Integrated Circuit Emphasis (SPICE), can be achieved and operated by proper connections to a Personal Computer (PC) and by dedicated software drivers that control the communication protocol between the smart card and the card terminal. We have also constructed an integrated test environment to verify the system developed. Through this test environment, we should be able to check all operational functions of the SoC-based developed smart card terminal microprocessor and smart card interface. The results showed that our test board operated successfully.

Secure transmission of the prescription order communication system based on the internet and the public-key infrastructure using master smart cards in the 2-way type terminal

This research paper presents a new systems design and development of the prescription order communication system (POCS) based on the Internet between the hospital and the pharmacy, on the public-key infrastructure, and on the concurrently parallel co-operation with both medical professionals and patients smart cards in the 2-way type terminal under the synchronized status. Concurrently parallel co-operation method at the synchronized status has been proposed in order to merge the digital signature generated by a medical professional with a patients prescription data. The digital signatures written by the medical doctors and pharmacists holding and using their individually master smart cards are applied to all contents of the prescription stored on a patients slave smart card at the synchronized status in the 2-way type terminal. Therefore, digital signatures for all prescriptions stored on the smart card in the developed prototype system should effectively he used to prevent being altered, forged, and reused by unauthorized users and being repudiated by medical professionals.

Conditional Access Module Systems for Digital Contents Protection Based on Hybrid/Fiber/Coax CATV Networks

In this paper, we have proposed the merging of the OpenCable reference model with the smart card interface defined by ISO/IEC 7816-3 and have implemented a new Conditional Access System (CAS) using this interface along with a Personal Computer Memory Card International Association (PCMCIA) interface. In addition, we have also designed the hardware architecture of the Point-of-Deployment (POD) security module, designed with the Verilog HDL, using the above two interfaces. The designed POD security module has an embedded 32-bit Reduced Instruction Set Computer (RISC) microprocessor that manages applications, such as an MPEG-2 filter, descrambler, and Data Encryption Standard (DES). We have tested this modeled and designed system using a prototype and show satisfactory simulation results.