• Journal of KIISE:Databases
• /
• v.33 no.2
• /
• pp.151-162
• /
• 2006

RDF Semantics, one of W3C Recommendations, provides the RDFS entailment rules, which are used for the RDFS inference. Sesame, which is well known RDF repository, supports the RDBMS-based RDFS inference using the forward-chaining strategy. Since inferencing in the forward-chaining strategy is performed in the data loading time, the data loading time in Sesame is slow down be inferencing. In this paper, we propose the order scheme for applying the RDFS entailment rules to improve inference performance. The proposed application order makes the inference process terminate without repetition of the process for most cases and guarantees the completeness of inference result. Also the application order helps to reduce redundant results during the inference by predicting the results which were made already by previously applied rules. In this paper, we show that our approaches can improve the inference performance with comparisons to the original Sesame using several real-life RDF datasets.

• Journal of Internet Computing and Services
• /
• v.11 no.1
• /
• pp.1-13
• /
• 2010

It is not easy to set RED(Random Early Detection) parameter according to environment in managing Network Device. Especially, it is more difficult to set parameter in the case of maintaining the constant service rate according to the change of environment. In this paper, we hypothesize the router that has Multi-core CPU in output queue and propose AI RED(Artificial Intelligence RED), which directly induces Genetic Algorithm of Artificial Intelligence in the output queue that is appropriate to the optimization of parameter according to RED environment, which is automatically adaptive to workload. As a result, AI RED Is simpler and finer than FuRED(Fuzzy-Logic-based RED), and RED parameter that AI RED searches through simulations is more adaptive to environment than standard RED parameter, providing the effective service. Consequently, the automation of management of RED parameter can provide a manager with the enhancement of efficiency in Network management.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.10
• /
• pp.4661-4680
• /
• 2016

Cognitive radio (CR) technology is an effective solution to the spectrum scarcity issue. Collaborative spectrum sensing is known as a promising technique to improve the performance of spectrum sensing in cognitive radio networks (CRNs). However, collaborative spectrum sensing is vulnerable to spectrum data falsification (SSDF) attack, where malicious users (MUs) may send false sensing data to mislead other secondary users (SUs) to make an incorrect decision about primary user (PUs) activity, which is one of the key adversaries to the performance of CRNs. In this paper, we propose a coalition based malicious users detection (CMD) algorithm to detect the malicious user in CRNs. The proposed CMD algorithm can efficiently detect MUs base on the Geary'C theory and be modeled as a coalition formation game. Specifically, SSDF attack is one of the key issues to affect the resource allocation process. Focusing on the security issues, in this paper, we analyze the power allocation problem with MUs, and propose MUs detection based power allocation (MPA) algorithm. The MPA algorithm is divided into two steps: the MUs detection step and the optimal power allocation step. Firstly, in the MUs detection step, by the CMD algorithm we can obtain the MUs detection probability and the energy consumption of MUs detection. Secondly, in the optimal power allocation step, we use the Lagrange dual decomposition method to obtain the optimal transmission power of each SU and achieve the maximum utility of the whole CRN. Numerical simulation results show that the proposed CMD and MPA scheme can achieve a considerable performance improvement in MUs detection and power allocation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.9
• /
• pp.2369-2378
• /
• 2009

In this paper, we implement measurement functionality for performance measurement of the GSM (Global System for Mobile Communication) terminal by using software. Generally speaking, the receiving algorithms in normal modems cannot be used directly to the measurement system due to the lack of the algorithm accuracy. In this paper, we propose the new receiver algorithm for precise GSM signal measurements. In the receiving algorithm, 2-stage (coarse stage, fine stage) parameters estimation (symbol-timing, frequency offset, carrier phase) scheme is used. To improve the estimation accuracy, we increase the number of the received signal samples by interpolation. The proposed GSM signal measurement algorithm can be used for verifying the hardware measurement system. In addition, the proposed algorithm can be used for the commercial system through code execution speed optimization.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.5
• /
• pp.863-870
• /
• 2019

In the GSM method for OWC-MIMO System, it is important to select an activation pattern set(: APS) for the performance optimization in the environment where mutual interference is high depending on the location of the transmitter and receiver. However, due to the high computational complexity, a high cost is paid in selecting the transmission APS. In this paper, we propose a method to reduce the candidate APS by pre-determining basic APS when generating candidate APS. The simulation results show that the proposed method has the same BER performance and reduce the computational complexity by 90% compared to the general GSM method in the high interfering environment.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.1
• /
• pp.13-24
• /
• 2019

This paper brings up fallacy of material factors specified for the design of concrete members in the current Korean limit state design code for highway bridges, and proposes new material factors based on a robust optimization scheme to overcome the fallacy. It is shown that the current load factors in the code and the proposed material factors lead to a much higher reliability index than the target index. The load factors are adjusted to yield the target reliability index using the inverse reliability analysis. A reliability-based approach following the basic concept of Eurocode is formulated to determine material factors as well as load factors. The load-material factors obtained by the proposed reliability-based approach yield a lower reliability level than the target index. Drawbacks of the basic concept of Eurocode are discussed. It is pointed out that differences in the uncertainties between materials and members may cause the lower reliability index of concrete member than the target.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.20 no.1
• /
• pp.3-16
• /
• 2010

Recently in the field of the wireless sensor network, many researchers are attracted to pairing cryptography since it has ability to distribute keys without additive communication. In this paper, we propose efficient hardware implementation of ${\eta}_T$ pairing which is one of various pairing scheme. we suggest efficient hardware architecture of ${\eta}_T$ pairing based on parallel processing and register/resource optimization, and then we present the result of our FPGA implementation over GF($2^{239}$). Our implementation gives 15% better result than others in Area Time Product.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.9
• /
• pp.1382-1391
• /
• 2022

White-box cryptography can respond to white-box attacks that can access and modify memory by safely hiding keys in the lookup table. However, because the size of lookup tables is large and the speed of encryption is slow, it is difficult to apply them to devices that require real-time while having limited resources, such as IoT(Internet of Things) devices. In this work, we propose a scheme for collecting short-length plaintexts and processing them at once, utilizing the characteristics that white-box ciphers process encryption on a lookup table size basis. As a result of comparing the proposed method, assuming that the table sizes of the Chow and XiaoLai schemes were 720KB(Kilobytes) and 18,000KB, respectively, memory usage reduced by about 29.9% and 1.24% on average in the Chow and XiaoLai schemes. The latency was decreased by about 3.36% and about 2.6% on average in the Chow and XiaoLai schemes, respectively, at a Traffic Load Rate of 15 Mbps(Mega bit per second) or higher.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.8
• /
• pp.2529-2551
• /
• 2022

Visual servoing (VS) based on the Kalman filter (KF) algorithm, as in the case of KF-based image-based visual servoing (IBVS) systems, suffers from three problems in uncalibrated environments: the perturbation noises of the robot system, error of noise statistics, and slow convergence. To solve these three problems, we use an IBVS based on KF, African vultures optimization algorithm enhanced extreme learning machine (AVOA-ELM), and fuzzy logic (FL) in this paper. Firstly, KF online estimation of the Jacobian matrix. We propose an AVOA-ELM error compensation model to compensate for the sub-optimal estimation of the KF to solve the problems of disturbance noises and noise statistics error. Next, an FL controller is designed for gain adaptation. This approach addresses the problem of the slow convergence of the IBVS system with the KF. Then, we propose a visual servoing scheme combining FL and KF-AVOA-ELM (FL-KF-AVOA-ELM). Finally, we verify the algorithm on the 6-DOF robotic manipulator PUMA 560. Compared with the existing methods, our algorithm can solve the three problems mentioned above without camera parameters, robot kinematics model, and target depth information. We also compared the proposed method with other KF-based IBVS methods under different disturbance noise environments. And the proposed method achieves the best results under the three evaluation metrics.

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.12
• /
• pp.105-114
• /
• 2023

In this paper, we propose a deployment and operation scheme of UxNB network toward mobile IAB. By operating a UxNB network based on SDN(Software Defined Network), UxNBs are deployed in areas where mobile communication services are desired. After deploying UxNB in the service area, IAB can be set up to perform mobile communication services. For this purpose, this paper first proposes a UxNB Network Controller consisting of a UAV Controller and an SDN Controller, and proposes the necessary functions. Next, we present a scenario in which a UxNB network can be deployed and operated in detail step by step. We also discuss the location of the UxNB network controller, how to deliver control commands from the UAV controller to the UxNB, how to apply IAB for UxNB networks, optimization of UxNB networks, RLF(radio link failure) recovery in UxNB networks, and future research on security in UxNB networks. It is expected that the proposed UxNB Network Controller architecture and UxNB network deployment and operation will enable seamless integration of UxNB networks into Mobile IAB.