• The KIPS Transactions:PartC
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• v.15C no.6
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• pp.469-480
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• 2008

The recently proposed RFID(Radio Frequency Identification) authentication protocol based on a hash function can be divided into two types according to the type of information used for authentication between a reader and a tag: either a value fixed or one updated dynamically in a tag memory. In this paper, we classify the protocols into a static ID-based and a dynamic-ID based protocol and then analyze their respective strengths and weaknesses. Also, we define a new security model including forward/backward traceability, synchronization, forgery attacks. Based on the model, we analyze the previous protocols and propose a new dynamic-ID based RFID mutual authentication protocol. Our protocol provide enhanced RFID user privacy compared to previous protocols and identify a tag efficiently in terms of the operation quantity of a tag and database.

• Journal of KIISE:Databases
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• v.33 no.3
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• pp.251-260
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• 2006

Homology searching on the primary structure (i.e., amino acid arrangement) of protein sequences is an essential part in predicting the functions and evolutionary histories of proteins. However, proteins distant in an evolutionary history do not conserve amino acid residue arrangements, while preserving their structures. Therefore, homology searching on proteins' secondary structure is quite important in finding out distant homology. In this manuscript, we propose an indexing scheme for efficient approximate searching on the secondary structure of protein sequences which can be easily implemented in RDBMS. Exploiting the concept of clustering and lookahead, the proposed indexing scheme processes three types of secondary structure queries (i.e., exact match, range match, and wildcard match) very quickly. To evaluate the performance of the proposed method, we conducted extensive experiments using a set of actual protein sequences. CSI was proved to be faster than the existing indexing methods up to 6.3 times in exact match, 3.3 times in range match, and 1.5 times in wildcard match, respectively.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.8-17
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• 2014

Petascale systems(so called supercomputers) have been mainly used for supporting communication-intensive and tightly-coupled parallel computations based on message passing interfaces such as MPI(HPC: High-Performance Computing). On the other hand, computing paradigms such as High-Throughput Computing(HTC) mainly target compute-intensive (relatively low I/O requirements) applications consisting of many loosely-coupled tasks(there is no communication needed between them). In Korea, recently emerging applications from various scientific fields such as pharmaceutical domain, high-energy physics, and nuclear physics require a very large amount of computing power that cannot be supported by a single type of computing resources. In this paper, we present our HTCaaS(High-Throughput Computing as a Service) which can leverage national distributed computing resources in Korea to support these challenging HTC applications and describe the details of our system architecture, job execution scenario and case studies of various scientific applications.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.55-67
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• 2012

Real-time image georeferencing is required to generate spatial information rapidly from the image sequences acquired by multi-sensor systems. To complement the performance of position/attitude sensors and process in real-time, we should employ on-line aerial triangulation based on a sequential estimation algorithm. In this study, we thus attempt to derive an efficient on-line aerial triangulation algorithm for real-time georeferencing of image sequences. We implemented on-line aerial triangulation using the existing Given transformation update algorithm, and a new inverse normal matrix update algorithm based on observation classification, respectively. To compare the performance of two algorithms in terms of the accuracy and processing time, we applied these algorithms to simulated airborne multi-sensory data. The experimental results indicate that the inverse normal matrix update algorithm shows 40 % higher accuracy in the estimated ground point coordinates and eight times faster processing speed comparing to the Given transformation update algorithm. Therefore, the inverse normal matrix update algorithm is more appropriate for the real-time image georeferencing.

• Journal of Broadcast Engineering
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• v.17 no.2
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• pp.344-353
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• 2012

In this paper, we propose a super-resolution algorithm using discrete wavelet transform. In general super-resolution algorithms for single-image, probability based operations have been used for searching high-frequency components. Consequently, the complexity of the algorithm causes the increase of processing time. In the proposed algorithm, we use discrete wavelet transform to find high-frequency sub-bands. We perform inverse discrete wavelet transform using input image and high-frequency sub-bands of the same resolution as the input image which are obtained by performing discrete wavelet transform without down-sampling and then we obtain image with high-resolution. In the proposed algorithm, we use the down-sampled version of the original image ($512{\times}512$) as a test image ($256{\times}256$) to compare the performance of algorithms. Through experimental results, we confirm the improved efficiency of the proposed algorithm comparing with conventional interpolation algorithms and also decreased processing time comparing the probability based operations.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.317-328
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• 2000

The objective of the research is to develop an algorithm for the optimum design of two-dimensional braced steel frames using an advanced analysis, which considers both material and geometric nonlinearties. Since both nonlinearties are considered in analysis process, Optimum design algorithm which does not require to calculate K-factor is presented. A multi-level discrete optimization technique with two parameters that uses the information of structural system and separate member has been developed. The structural analysis is performed by the relined plastic-hinge method which is based on zero-length plastic hinge theory. Optimization problem are formulated by AISC-LRFD code. The feasibility, validity and efficiency of the developed algorithm is demonstrated by the results of the braced steel frame.

• The Journal of the Korea Contents Association
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• v.16 no.10
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• pp.299-310
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• 2016

In this paper, we perform analysis of the performance of low-power communication technology, IEEE 802.15.4 MAC (Media Access Control) protocol used in internet of things. Wide variety of devices in internet of things generate different kinds of traffic characteristics and heterogeneous traffic environment is therefore considered in contrast to existing works. With the help of the Markov chain the performance of the protocol is derived as a function of the MAC parameters and based on the results a framework to determine energy-efficient optimal MAC parameters for applications in real time is proposed. Proposed method is shown to be more efficient in terms of energy consumption through performance comparison over application scenarios compared to operation with fixing MAC parameters, and its practicability on small devices with limited computing power is verified through evaluating the accuracy and speed of the proposed framework.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.114-126
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• 2009

In this paper, we propose a PSNR(peak-to-peak signal to noise ratio) estimation method exploiting visual rhythm information for the reconstructed video frames at the customer's STB(Set-top Box). Key idea is that we can estimate the PSNR by using VR(visual rhythm) information even though a VR consists of the pixels in a vertical direction of a 2D(2-dimensional) video frame, because VR is the 1D projected version of a 2D video frame approximately. Simulation results show that the estimated PSNR from VR information is closely related to the PSNR from 2D video frames. The advantages of the proposed scheme includes that it can monitor the video quality efficiently while minimizing the computation load of STB, and show the location, duration and occurrence count of severe picture degradation.

• Journal of the Korea Computer Industry Society
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• v.5 no.5
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• pp.721-728
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• 2004

OCSP (Online Certificate Status Protocol) server which checks the certificate status provides the real time status verification in the PKI (Public Key Infrastructure) system which is the essential system of certificate. However, OCSP server need the message authentication with the server and client, so it has some shortcomings that has slow response time for the demands of many clients concurrently and has complexity of the mathematical process in the public encryption system. In this research, simulation model of the certificate status vertification server is constructed of the DEVS (Discrete EVent system Specification) formalism. This sever model is constructed to practice the authentication with hash function when certificate is checked. Simulation results shows the results of increase of the certificate status verification speed and decrease of the response time to the client.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.210-216
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• 2009

Several empty-space leaping methods have been proposed for CPU-based volume ray casting. When sample points are located in semi-transparent cells, however, previous leaping methods perform unnecessary resamplings even if the scalar values on those points are confined within transparent range. A semi-transparent cells leaping method for volume ray casting using the Marching Cubes algorithm is proposed to solve this problem in our previous work. When a ray reaches a semi-transparent cell, our method performs in-out test between current sample point and the bounding box enclosing the triangles generated by the Marching Cubes. If the sample point lies on outside of the bounding box, we estimate the point is regarded as transparent. In this case, the ray advances to the next sample point without performing a resampling operation. We can frequently refer the tables for neighboring voxels, however, when we exploit conventional data structures of the Marching Cubes. We propose modified Marching Cubes tables for solving this problem.