• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.70-77
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• 1996

In this study, sliding response analysis of free standing structure such as multi-purpose nuclear spent fuel storage cask is peformed. The governing factors of sliding response are aspect ratio of structure and ground acceleration. The vertical acceleration component is very important factor in the sliding response of the structure. Based on the mathematical model, computer program is developed using direct forward integration method to predict the sliding response. Using the program, several parametric studies were made for sinusodial ground motion and for El Centre 1940 earthquake and Mexico 1973 earthquake. From the results, it is known that the frequency content and duration of strong motion affect the sliding of the structure.

• Journal of Hydrospace Technology
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• v.1 no.1
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• pp.29-40
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• 1995

This paper describes the procedure to predict steady and unsteady performances of a contrarotating propeller(CRP) by a mixed formulation of the boundary value problem(BVP) far the flow around a CRP. The blade BVP is treated by a classical vortex lattice method, whereas the hub BVP is solved by a potential-based panel method. Blades and trailing wakes are represented by a vortex and/or source lattice system, and hubs are represented by normal dipole and source distributions. Both forward and aft propellers are solved simultaneously, thus treating the interaction effect without iteration. The unsteady performance is computed directly in time domain. The new numerical procedure requires a large amount of storage and computing time, which is however no longer a limit in a modern computer system. Sample computations show that the steady performance compares very well with the experiments. The predicted unsteady behavior shows that the dominant harmonics of the total forces are multiples of not only the number of blades of the forward and aft propellers but also the product of both blade numbers. The magnitude of the latter harmonics, present also in uniform oncoming flow, may reach abort 50% of the mean torque for the aft propeller, which in turn may cause a serious vibration problem in the complicated contrarotating shafting system.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.3
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• pp.253-258
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• 2004

To get accurate information about the defect from the test signal, NDT engineers should have a good knowledge on forward problems. Such knowledge is usually obtained by a lot of testing experiences. Another why of obtaining such knowledge is to build a database containing lots of defect information and their corresponding signals. However, the archiving of raw test data would require a lot of storage space. In this paper, an economic way of storing signals is studied by using Fourier descriptors. Instead of saving raw signal data, Fourier descriptors are saved and the storage spare is reduced. Of course, the defect signal can be reconstructed from the stored descriptors. By using differential ECT signals produced by numerical modeling and experiment, the savings of 85% from the original signal and $57{\sim}65%$ from the filtered signal in the storage space were confirmed. The similarity of the reconstructed signal and the original signal was also demonstrated. This Fourier descriptor approach could contribute significantly in building differential signal databases.

• Journal of Power Electronics
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• v.13 no.4
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• pp.516-527
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• 2013

This paper presents a new overall system for state-of-available-power (SoAP) prediction for a lithium-ion battery pack. The essential part of this method is based on an adaptive network architecture which utilizes both fuzzy model (FIS) and artificial neural network (ANN) into the framework of adaptive neuro-fuzzy inference system (ANFIS). While battery aging proceeds, the system is capable of delivering accurate power prediction not only for room temperature, but also at lower temperatures at which power prediction is most challenging. Due to design property of ANN, the network parameters are adapted on-line to the current battery states (state-of-charge (SoC), state-of-health (SoH), temperature). SoC is required as an input parameter to SoAP module and high accuracy is crucial for a reliable on-line adaptation. Therefore, a reasonable way to determine the battery state variables is proposed applying a combination of several partly different algorithms. Among other SoC boundary estimation methods, robust extended Kalman filter (REKF) for recalibration of amp hour counters was implemented. ANFIS then achieves the SoAP estimation by means of time forward voltage prognosis (TFVP) before a power pulse occurs. The trade-off between computational cost of batch-learning and accuracy during on-line adaptation was optimized resulting in a real-time system with TFVP absolute error less than 1%. The verification was performed on a software-in-the-loop test bench setup using a 53 Ah lithium-ion cell.

• Journal of Information Processing Systems
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• v.17 no.1
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• pp.37-50
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• 2021

Query applications based on nested data, the most commonly used form of data representation on the web, especially precise query, is becoming more extensively used. MapReduce, a distributed architecture with parallel computing power, provides a good solution for big data processing. However, in practical application, query requests are usually concurrent, which causes bottlenecks in server processing. To solve this problem, this paper first combines a column storage structure and an inverted index to build index for nested data on MapReduce. On this basis, this paper puts forward an optimization strategy which combines query execution service tree and frequent sub-query trajectory to reduce the response time of frequent queries and further improve the efficiency of multi-user concurrent queries on large scale nested data. Experiments show that this method greatly improves the efficiency of nested data query.

• Journal of the Korea Society of Computer and Information
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• v.18 no.11
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• pp.115-124
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• 2013

In this paper, we suggest a secure data dissemination by Lightweight Individual Encryption Multicast scheme over wireless sensor networks using the individual encryption method with Forward Error Correction instead of the group key encryption method. In wireless sensor networks, a sink node disseminates multicast data to the number of sensor nodes to update the up to date software such as network re-programming and here the group key encryption method is the general approach to provide a secure transmission. This group key encryption approach involves re-key management to provide a strong secure content distribution, however it is complicated to provide group key management services in wireless sensor networks due to limited resources of computing, storage, and communication. Although it is possible to control an individual node, the cost problem about individual encryption comes up and the individual encryption method is difficult to apply in multicast data transmission on wireless sensor networks. Therefore we only use 0.16% of individually encrypted packets to securely transmit data with the unicast to every node and the rest 99.84% non-encrypted encoded packets is transmitted with the multicast for network performance.

• Quality Improvement in Health Care
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• v.5 no.2
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• pp.258-276
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• 1998

This study was conducted to justify the "prescribed shelf life" currently used in Samsung Medical Center and give recommendations based on scientific data to adopt for safe and cost-effective storage times for sterile goods Since the early 1970's, predetermined expiration dating policy has been used in Korea on all in-house sterilized products like any other countries; six months for the supplies wrapped in polyethylene peel pouches and two weeks for the rest. Recently, however, the studies suggest that current standards for preserving the sterility can be changing. It looks like we unnecessarily have too-short expiration date of sterilized supplies, that is far from being cost effective. Certainly, this research is an exciting project, especially in Korea, and will be leading and contributing to the paradigm shift of the conservative concept of shelf life for sterile supplies in Korean healthcare facilities. The major goal of this study was placed on the measurement of the recontamination time in packs wrapped in all kinds of wrapping materials used in S.M.C and stored in various conditions for periods ranging from three months to six months, and then develop a practical standard of "shelf life" based on the analyzed data. Objectives: To measure and compare the recontamination time of sterile packs among wrapppers and storage conditions, and develop a practical standard for the shelf life and storage conditions of sterile products. Samples and Method: The sterile integrity was investigated of the total 1,440 sterile sample packs containing gauze strip($1.5cm{\times}0.5cm$) we prepared and wrapped in nine wrapping materials (randomized reprocessed linens, linens reprocessed 99 times, linens reprocessed 120 times, new kraft paper, used kraft paper, new nonwoven fabrics, 6-time reprocessed nonwoven fabrics, new polyethylene peel pouches, used polyethylene peel pouches), and stored in four locations(closed cabinet of one of the typical wards, open shelf of one of ICUs, open shelf of separate storage room in ER, open shelf in OR), for three to six months, respectively in 1998. Each type of packs were opened weekly and the gauze strips inoculated into Brewer's thioglycollate broth at $35^{\circ}C$ for seven days. Results: There was no growth found for any types of the pack and storage conditions studied. Discussion: This study was conducted in an attempt to identify the possibility of extending the current shelf life for sterile goods we use in a sense of cost effectiveness. The findings suggest that we could extend our expiration dates, that means we can save a lot of materials and personnel time meeded for resterilizing, outdating, recleaning, wrapping, and reshelving. Then it will initiate a great reform in the field of healthcare in Korea, and now we are looking forward to this valuable revolution. We are going to continue this study and take all steps need to apply this new concept to our practice, and then trying to extend to other hospitals.