• The KIPS Transactions:PartC
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• v.14C no.1 s.111
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• pp.45-54
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• 2007

As one of the most threatening attacks, DDoS attack makes distributed multiple agents consume some critical resources at the target within the short time, thus the extent and scope of damage is serious. Against the problems, the existing defenses focus on detection, traceback (identification), and filtering. Especially, in the hierarchical networks, the traffic congestion of a specific node could incur the normal traffic congestion of overall lower nodes, and also block the control traffic for notifying the attack detection and identifying the attack agents. In this paper, we introduce a DDoS attack tolerant network structure using a hierarchical overlay for hierarchical networks, which can convey the control traffic for defense such as the notification for attack detection and identification, and detour the normal traffic before getting rid of attack agents. Lastly, we analyze the overhead of overlay construction, the possibility of speedy detection notification, and the extent of normal traffic transmission in the attack case through simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.10
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• pp.843-850
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• 2005

FBA(flux balance analysis) with Boolean rules for representing regulatory events has correctly predicted cellular behaviors, such as optimal flux distribution, maximal growth rate, metabolic by-product, and substrate concentration changes, with various environmental conditions. However, until now, since FBA has not taken into account a hierarchical regulatory network, it has limited the representation of the whole transcriptional regulation mechanism and interactions between specific regulatory proteins and genes. In this paper, in order to solve these problems, we describe the construction of hierarchical regulatory network with defined symbols and the introduction of a weight for representing interactions between symbols. Finally, the whole cellular behaviors with time were simulated through the linkage of a hierarchical regulatory network module and dynamic simulation module including FBA. The central metabolic network of E. coli was chosen as the basic model to identify our suggested modeling method.

• Journal of the Korea Society of Computer and Information
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• v.18 no.7
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• pp.111-123
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• 2013

To verify software vulnerability, the method of conjecturing software structure and then testing the software based on the conjectured structure has been highlighted. To utilize the method, an efficient way to conjecture software structure is required. The popular graph and tree methods such as DFG(Data Flow Graph), CFG(Control Flow Graph) and CFA(Control Flow Automata) have a serious drawback. That is, they cannot express software in a hierarchical fashion. In this paper, we propose a method to overcome the drawback. The proposed method applies various input data to a binary code, generate CFG's based on the code output and construct a HCFG (Hierarchical Control Flow Graph) to express the generated CFG's in a hierarchical structure. The components required for HCFG and progressive algorithm to construct HCFG are also proposed. The proposed method is verified through constructing the software architecture of an open SMTP(Simple Mail Transfer Protocol) server program. The structure generated by the proposed method and the real program structure are compared and analyzed.

• Korean Journal of Applied Biomechanics
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• v.34 no.3
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• pp.115-124
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• 2024

Objective: Based on the uncontrolled manifold (UCM) framework, this study investigated the hierarchical organization of redundant motor elements in multi-digit prehension, focusing on moment production across two control hierarchies. Method: Twelve adult males participated in the current experiment where they grasped a customized handle to generate and maintain target moments under isometric conditions in both pronation and supination directions. The forces exerted by the digits, recorded via transducers on the handle, underwent UCM analysis. This analysis quantified the synergistic actions across the upper and lower control hierarchies for stabilizing moments and grip forces. Additionally, synergy properties for lateral and medial fingers were analyzed to assess their distinct contributions (finger specialization) to moment and force stabilization. Results: Our findings revealed that the thumb and virtual finger contribute differently to net moment generation according to the direction of the moment, reflecting the different abilities of the individual fingers to produce moments. In the upper hierarchy, synergistic actions were notably stronger, effectively stabilizing both moments and grip forces. In contrast, the lower control hierarchy demonstrated a lack of synergy in force stabilization (trade-off synergy), although synergy in moment stabilization was preserved. Further, lateral fingers were found to play a more significant role in stabilizing moments compared to medial fingers. Conclusion: The pronounced synergy in grip force observed in the upper hierarchy implies that grip stabilization is likely an intrinsic strategy of the central nervous system, rather than merely a mechanical consequence. Furthermore, synergistic covariations of digit moments in both hierarchies indicate the neural controller's capability to generate synergies across hierarchies for stable multi-digit moment production. The notable contribution of lateral fingers in moment stabilization provides supporting evidence of finger specialization. Overall, this study elucidates the hierarchical interplay of redundant elements to achieve task-specific stability, especially in multi-digit prehension.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.1
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• pp.103-118
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• 1995

This paper is concerned with developing flow control method for a dynamic multistage manufacturing system with interstage buffers and unreliable machines. For the effective control of proposed manufacturing system, the three-level hierarchical scheme is introduced. At the top level, we collect the system data and then, design the buffer sizes and hedging points. Short-term production rates are calculated at the middle level. At the bottom level, actual dispatching times are determined by Clear the Largest Buffer Level rule. The control method utilizes the material and the space in the buffers to alleviate the propagation of a failure to other machines in the system and keeps the production close to demand. Finally, a numerical example is provided to illustrate the mathematical control method developed and implemented in a dynamic manufacturing environment.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1161-1166
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• 1989

In this paper, a hierarchical state feedback control method is proposed for the optimal tracking of large-scale discrete-time systems with time-delays. The state feedback gain matrix and the compensation vector are computed from the optimal trajectories of the state variables and control inputs obtained hierarchically by the open-loop control method based on the interaction prediction method. The resulting feedback gain matrix and the compensation vector are optimal for the given initial condition. Computer simulation results show that the proposed method has better control performance and fewer second level iterations than the Tamura method.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.2
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• pp.108-113
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• 2005

This paper suggests a control method for an efficient topology/parameter evolution in a bond graph-based GP design framework that automatically synthesizes designs for multi-domain, lumped parameter dynamic systems. We adopt a hierarchical breeding control mechanism with fitness-level-dependent differences to obtain better balancing of topology/parameter search - biased toward topological changes at low fitness levels, and toward parameter changes at high fitness levels. As a testbed for this approach in bond graph synthesis, an eigenvalue assignment problem, which is to find bond graph models exhibiting minimal distance errors from target sets of eigenvalues, was tested and showed improved performance for various sets of eigenvalues.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.492-503
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• 1994

In this study, the control and scheduling of the flexible manufacturing cell (FMC) is discussed, which can perform the mixed production and relieve the effect of machine failure. The control of the FMC isvery complex task due to the property of multiple jobs and the dynamically changing states. For effective control of proposed FMC, the hierarchical scheme is introduced and the functions of each levels are defined. Especially for the control functions of shop floor level and cell level, the intelligent scheduler is implemented. To show the efficiency of the intelligent scheduler, the production method fo the existing assembly lines was evaluated and compared with the proposed intelligent FMC method. The results from the production performance show that the proposed method is superior to the existing method in various performance indices.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.104-112
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• 2006

ZigBee is the emerging industrial standard for ad hoc networks based on IEEE 802.15.4. It is used for low data rate and low power wireless network applications. Expected applications of ZigBee include wireless sensor networks for remote monitoring, home control, and industrial automation. Since one of the most important design goals of ZigBee is to reduce the installation and running costs, the ZigBee stack is embedded in the cheap and small micro-controller unit. The hierarchical routing algorithm is used for ZigBee end devices which have very limited resources. Using the block addressing scheme, end devices can send data to the destination without a routing table. However, hierarchical routing has the problem that the packets follow the tree hierarchy to the destination even if the destination is located nearby. In this paper, we propose a scheme to improve the hierarchical routing algorithm in ZigBee networks by employing the neighbor table that is originally used together with the routing table. We suggest selecting the neighbor node that has the minimum remaining hops to the destination as the next hop node. Simulation result shows that the proposed scheme saves more than 30% of the hop counts compared with the original hierarchical routing.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.299-313
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• 2002

Recently, the demand for mobile communications and multimedia services has rapidly increased so that conventional cellular system cannot fulfill the requirement of users (capacity and QoS) any more. Therefore, the hierarchical cellular system has been suggested in order to guarantee the QoS and to admit large population of users. IMT-2000 adopts the hierarchical cellular structure, which requires a call control algorithm capable of manipulating and utilizing the complicated structure of hierarchical cellular structure with handiness and efficiency. In this thesis, as an improvement of conventional combined algorithm, a new call control algorithm considering the moving speed of terminal and bandwidth is suggested. This algorithm employs buffers and guard channels to reduce the failure rate. Also, this algorithm considers the moving speed of terminal and bandwidth to elevate the efficiency. Furthermore, calls are handled separately according to the moving speeds of terminal and bandwidths to improve the QoS and reduce the handover rate. As an evaluation of the suggested algorithm, a model hierarchical cellular system is constructed and simulations are conducted with various types of traffic. As the result of the simulations, such indices as block rate, drop rate, channel utilization, and the number of inter layer handovers are examined to demonstrate the excellency fo the suggested algorithm.