• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1682-1685
• /
• 2005

System algorithms estimated by deterministic input may occur the error between predicted and actual output. Especially, actual system can't predict the exact outputs due to uncertainty and tolerance of input parameters. A single output to a set of inputs has a limited value without the variation. Hence, we should consider various scatters caused by the load assessment, material characteristics, stress analysis and manufacturing methods in order to perform the robust design or estimate the reliability of structure. The system design with uncertainty should perform the probabilistic structural optimization with the statistical response and the reliability. This method calculated the probability distributions of the characteristics such as stress by combining stress analysis, response surface methodology and Monte-Carlo Method and got the probabilistic sensitivity. The sensitivity of structural response with respect to inconstant design variables was estimated by fracture probability. Therefore, this paper proposed the probabilistic reliability design method for fracture of uncorved freight end beam and the design criteria by fracture probability.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.4
• /
• pp.235-245
• /
• 2004

In this paper, fault tolerant mechanisms are presented for a servo manipulator system designed to operate in a hot cell. A hot cell is a sealed and shielded room to handle radioactive materials, and it is dangerous for people to work in the hot cell. So, remote operations are necessary to handle the radioactive materials in the hot cell. KAERI has developed a servo manipulator system to perform such remote operations. However, since electric components such as servo motors may fail by radiation, fault tolerant mechanisms have to be considered. For fault tolerance of the servo manipulator system, duplication mechanism increasing the reliability of the transport's driving motors and reconfiguration algorithm accommodating the slave's motor failure have been presented. The reconfiguration algorithm recovering the end effector's motion in spite of one motor's failure is based on control allocation redistributing redundant axes. The constrained optimization method and pseudo inverse method have been adopted for control allocation. Simulation examples and real test results have been presented to verify the Proposed methods.

• Journal of Information Processing Systems
• /
• v.5 no.2
• /
• pp.69-76
• /
• 2009

Self healing systems are considered as cognation-enabled sub form of fault tolerance system. But our experiments that we report in this paper show that self healing systems can be used for performance optimization, configuration management, access control management and bunch of other functions. The exponential complexity that results from interaction between autonomic systems and users (software and human users) has hindered the deployment and user of intelligent systems for a while now. We show that if that exceptional complexity is converted into self-growing knowledge (policies in our case), can make up for initial development cost of building an intelligent system. In this paper, we report the application of AHSEN (Autonomic Healing-based Self management Engine) to in OKKAM Project infrastructure backbone cluster that mimics the web service based architecture of u-Zone gateway infrastructure. The 'blind' load division on per-request bases is not optimal for distributed and performance hungry infrastructure such as OKKAM. The approach adopted assesses the active threads on the virtual machine and does resource estimates for active processes. The availability of a certain server is represented through worker modules at load server. Our simulation results on the OKKAM infrastructure show that the self healing significantly improves the performance and clearly demarcates the logical ambiguities in contemporary designs of self healing infrastructures proposed for large scale computing infrastructures.

• Journal of the Microelectronics and Packaging Society
• /
• v.19 no.4
• /
• pp.13-18
• /
• 2012

By the need for high-speed data transmission in PCB, the studies on the optical PCB has been conducted with optical interconnection and its packaging technology. Particularly, the polymer-based optical interconnection has been extensively studied with the advantages such as cost-effective and ease of process. For high-efficiency and passive alignment, the studies were performed using the 45 degree mirrors, MT connector, and etc. In this work, integrated PLC device and fiber alignment array block was fabricated by using imprint technology to solve the alignment and array problem of optical device and the optical fiber. The fabricated integrated block for optical interconnection of PLC device has achieved higher precision of decreasing the dimensional error of the patterns by optimization of process and its insertion loss has an average value of 4.03dB, lower than criteria specified by international standard. In addition, a optical waveguide with built-in lens has been proposed for high-efficiency and passive alignment. By simulation, it was confirmed that the proposed structure has higher coupling efficiency than conventional no-lens structure and has the broad tolerance for the spatial offset of optical waveguide.

• Journal of Ocean Engineering and Technology
• /
• v.19 no.2 s.63
• /
• pp.40-46
• /
• 2005

In order to consider the statistical properties of probability variables which are used in structural analysis, the conventional approach of using safety factors based on past experience, are usually used to estimate the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, materials and dimensional characteristics. Errors should be considered systematically in the structural analysis. In this paper, we estimated the probability of failure of two pressure vessels, simultaneously, using computational analysis. One pressure vessel, theoretically, had no stiffener whereas the other had. This paper also discusses sensitivity values of random variables in the rounded parts of the pressure vessel which had ring-style stiffener in the center of the external area which had ring-style stiffener. Finally, we show that the reliability index, and the probability of failure, can be calculated to particular tolerance limits.

• International Journal of Control, Automation, and Systems
• /
• v.2 no.2
• /
• pp.256-262
• /
• 2004

Conventionally, profile non-uniformity has been characterized by relying on approximated profile with angle or anisotropy. In this study, a new non-uniformity model for etch profile is presented by applying a discrete wavelet to the image obtained from a scanning electron microscopy (SEM). Prediction models for wavelet-transformed data are then constructed using a back-propagation neural network. The proposed method was applied to the data collected from the etching of tungsten material. Additionally, 7 experiments were conducted to obtain test data. Model performance was evaluated in terms of the average prediction accuracy (APA) and the best prediction accuracy (BPA). To take into account randomness in initial weights, two hundred models were generated for a given set of training factors. Behaviors of the APA and BPA were investigated as a function of training factors, including training tolerance, hidden neuron, initial weight distribution, and two slopes for bipolar sig-moid and linear function. For all variations in training factors, the APA was not consistent with the BPA. The prediction accuracy was optimized using three approaches, the best model based approach, the average model based approach and the combined model based approach. Despite the largest APA of the first approach, its BPA was smallest compared to the other two approaches.

• Korean Journal of Computational Design and Engineering
• /
• v.9 no.1
• /
• pp.35-43
• /
• 2004

It is well known that the five-axis machining has advantages of tool accessibility and machined surface quality when compared with conventional three-axis machining. Traditional researches on the five-axis tool-path generation have addressed interferences such as cutter gouging, collision, machine kinematics and optimization of a CL(cutter location) or a cutter position. In the paper it is presented that optimal CL data for a face-milling cutter moving on a tool-path are obtained by incorporating TSS(tool swept surface) model. The TSS model from current CL position to the next CL position is constructed based on machine kinematics as well as cutter geometry, with which the deviation from the design surface can be computed. Then the next CC(cutter-contact) point should be adjusted such that the deviation conforms to given machining tolerance value. The proposed algorithm was implemented and applied to a marine propeller machining, which proved effective from a quantitative point of view. In addition, the algorithm using the TSS can also be applied to avoid cutter convex interferences in general three-axis NC machining.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.8
• /
• pp.1055-1061
• /
• 2018

Recently, due to the rapid development of electric vehicle and energy storage system, it is emphasized for battery management system to be needed and to be improved. BMS carries out various movement for optimization the use of the energy and safe use of secondary battery, these movement of BMS start at high wattage shunt fixed resistor which performs a function for detecting current among the BMS components. In addition, for the safe operation of secondary battery, the reliability of current voltage variation detected from shunt should be secured, and for corresponding characteristics, the quality of Temperature coefficient of resistance for BMS shunt and the quality of Thermo electromotive force all must be excellent. For these reasons, this study comes up with the stabilization plan for thermo electromotive force and temperature coefficient of resistance of BMS shunt resistor which is key to secondary battery operation.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.2
• /
• pp.148-153
• /
• 2012

In this paper, we propose a fault-tolerant QoS routing scheme based on interference awareness for providing both high throughput and minimum end-to-end delay for wireless sensor networks. With the proposed algorithm, it is feasible to find out the optimal transmission path between sensor nodes to the sink node by using cumulative path metric where real-time delivery, high energy efficiency and less interference are considered as in path selection. Finally, simulation results show that network throughput and delay can be improved by using the proposed routing scheme.

• Journal of Gastric Cancer
• /
• v.4 no.2
• /
• pp.59-74
• /
• 2004

This report attempts to explain the (i) implications of comorbidity for research and practice in the fieldo of oncology, (ii) the approach for dosing of anti-cancer drugs in the presence of comorbidity, as an example of its clinical application, and finally (iii) the dosing guidelines for the anticancer drugs clinically active in gastric cancer in the presence of renal or liver dysfunction. This has resulted from the idea of approaching comorbidity in a systematic way and of integrating it with oncologic decisions. Various methods have been used to assess comorbidity. However, significant work remains to be done to analyze how various diseases combine to influence the oncologic outcome. The main end-point explored so far has been mortality, but a largely open challenge remains to correlate comorbidity with treatment tolerance and functional and quality of life, as well as to integrate it in clinical decision-making. Cancer chemotherapy in comorbidity should be considered as an example of the need for dose optimization in individual patients, and it should be determined by considering the basic principles of the pharmacokinetics and the pharmacodynamics of the agents. This review analyzes the available data on the pharmacokinetics and the toxicities of anti-cancer agents in the comorbidity population.