• Journal of Power System Engineering
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• v.8 no.4
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• pp.11-16
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• 2004

In this study, to investigate the effects of omitting low-amplitude cycles from a flight-simulation loading, crack growth tests were conducted on 2124-T851 aluminum alloy specimens. Three test spectra were generated by omitting small load ranges as counted by the rain-flow count method. The crack growth test results were compared with the data obtained from the flight-simulation loading. The experimental results show that the ranges equal to or smaller than 5% of the maximum load do not contribute to crack growth behavior because these are below the initial stress intensity factor range. Omitting these from the flight-simulation loading, test time can be reduced by 54%. However, in the case of omitting the load ranges below 15% of the maximum load, crack growth rates decreased, and crack growth curve deviated from the crack growth data under the flight-simulation loading because loading cycles above fatigue fracture toughness were omitted.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.1959-1975
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• 2011

Adaptive Bit Loading (ABL) in Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) is often used to achieve the desired Bit Error Rate (BER) performance in wireless systems. In this paper, we discuss some of the bit loading algorithms, compare them in terms of the BER performance, and present an effective and concise Adaptive Grouped Loading (AGL) algorithm. Furthermore, we propose a "weight factor" for loading algorithm to converge rapidly to the final solution for various data rate with variable Signal to Noise Ratio (SNR) gaps. In particular, we consider the bit loading in near optimal Singular Value Decomposition (SVD) based MIMO-OFDM system. While using SVD based system, the system requires perfect Channel State Information (CSI) of channel transfer function at the transmitter. This scenario of SVD based system is taken as an ideal case for the comparison of loading algorithms and to show the actual enhancement achievable by our AGL algorithm. Irrespective of the CSI requirement imposed by the mode of the system itself, ABL demands high level of feedback. Grouped Loading (GL) would reduce the feedback requirement depending upon the group size. However, this also leads to considerable degradation in BER performance. In our AGL algorithm, groups are formed with a number of consecutive sub-channels belonging to the same transmit antenna, with individual gains satisfying predefined criteria. Simulation results show that the proposed "weight factor" leads a loading algorithm to rapid convergence for various data rates with variable SNR gap values and AGL requires much lesser CSI compared to GL for the same BER performance.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.331-338
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• 2004

Stress transfer to the surrounding tissues is one of the factors involved in the design of dental implants. Unfortunately, insufficient data are available for stress transfer within the regenerated bone surrounding dental implants. The purpose of this study was to investigate the concentration of stresses within the regenerated bone surrounding the implant using three-dimensional finite element stress analysis method. Stress magnitude and contours within the regenerated bone were calculated. The $3.75{\times}10-mm$ implant (3i, USA) was used for this study and was assumed to be 100% osseointegrated, and was placed in mandibular bone and restored with a cast gold crown. Using ANSYS software revision 6.0, a program was written to generate a model simulating a cylindrical block section of the mandible 20 mm in height and 10 mm in diameter. The present study used a fine grid model incorporating elements between 165,148 and 253,604 and nodal points between 31,616 and 48,877. This study was simulated loads of 200N at the central fossa (A), at the outside point of the central fossa with resin filling into screw hole (B), and at the buccal cusp (C), in a vertical and $30^{\circ}$ lateral loading, respectively. The results were as follows; 1. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were increased from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, concentrated on the top of the cylindrical collar loading point B and C in vertical loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were increase from loading point A to C in vertical loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in vertical loading. 2. In case the regenerated bone (bone quality type IV) was surrounded by bone quality type I and II, stresses were decreased from loading point A to C in lateral loading. Stresses according to the depth of regenerated bone were concentrated on the top of the cylindrical collar in loading point A and B, distributed along the implant evenly in loading point C in lateral loading. And, In case the regenerated bone (bone quality type IV) was surrounded by bone quality type III, stresses were decreased from loading point A to C in lateral loading. And stresses according to the depth of regenerated bone were distributed along the implant evenly in loading point A, B and C in lateral loading. In summary, these data indicate that both bone quality surrounding the regenerated bone adjacent to implant fixture and load direction applied on the prosthesis could influence concentration of stress within the regenerated bone surrounding the cylindrical type implant fixture.

• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.810-818
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• 1991

Fracture responses of Al2O3 tubes were investigated for various loading paths under combined tension/torsion. The fracture criterion did not depend on loading paths. Fracture angles agreed well with the maximum tensile stress criterion. As the loading condition approaches a shear dominant state, the tensile principal stress at fracture increases compared to the uniaxial fracture strength. By using the Weibull modulus obtained from tension and torsion tests, the Weibull statistical fracture strengths were compared with experimental data. This comparison suggests that fracture may occur at the surface of the specimen when tensile stress is dominant, but within the volume of the specimen when shear stress is dominant. The Weibull fracture strength increased as the loading conition approached a shear dominant state, but underestimated compared to experimental data. Finally, a new fracture criterion was proposed by including the effect of compressive principal stress. The proposed criterion agreed well with experimental data of Al2O3 tubes not only at combined tension/torsion but also at balanced biaxial tension.

• Journal of the Korea Safety Management & Science
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• v.25 no.1
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• pp.15-21
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• 2023

In modern society, the delivery service market has grown explosively due to rapid changes in social structure and the recent COVID-19 pandemic. Therefore, various problems such as injury to workers and an increase in human accidents are occurring due to the loading and unloading of parcels. In order to solve this problem, domestic company n is developing a "robot-based cargo loading and unloading system". In developing a new technology system, quantitative reliability targets should be set for efficient operation and development. In this paper, reliability analysis was conducted through field data for the pneumatic gripper of the "robot-based cargo loading system". The reliability of the failure data was analyzed to estimate the distribution parameters and MTTF. Random data was derived for the probability of occurrence of a failure with the estimated value. By repeating the simulation to predict the number and year of failures according to the estimated parameters of the probability distribution, it was proposed as a method that reflects realistic probabilities rather than calculating with simple arithmetic using the average MTTF previously used in the field.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1616-1629
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• 2023

To quantify the conservatism of existing ASME strain-based evaluation methods for seismic loading, this paper presents very low cycle fatigue test data of elbows under various cyclic loading conditions and comparison of evaluation results with experimental failure cycles. For strain-based evaluation methods, the method presented in ASME BPVC CC N-900 and Sec. VIII are used. Predicted failure cycles are compared with experimental failure cycle to quantify the conservatism of evaluation methods. All methods give very conservative failure cycles. The CC N-900 method is the most conservative and prediction results are only ~0.5% of experimental data. For Sec. VIII method, the use of the option using code tensile properties gives ~3% of experimental data, and the use of the material-specific reduction of area can reduce conservatism but still gives ~15% of experimental data.

• Journal of Environmental Impact Assessment
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• v.14 no.3
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• pp.97-107
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• 2005

The purpose of this study is to develop a system, which estimates watershed pollutant loading rate through the combination of GIS and computational mode. Also, the applicability of this study was estimated by the application of the above system for Chuncheon City. The detailed results of these studies are as follows; The pollutant loading estimation system was developed for more convenient estimation of pollutant loading rate in watershed, and the system load was minimized by the separation of estimation module for point and non-point source. This system on the basis of GIS is very economical and efficient because it can be applied to other watershed with the watershed map. System modification is not needed. The pollutant loading estimation system for point source was developed to estimate the pollutant loading rate in watershed through the extraction of the proper data from all districts and yearly data and the execution of spatial analysis which is main function of GIS. From the verification result of spatial analysis, real watershed area and the administrative districtarea extracted by spatial analysis were $1,114,893,340.15m^2$ and $1,114,878,683.68m^2$, respectively. It shows that the spatial analysis results were very exact with only 0.001% error. The pollutant loading estimation system for non-point source was developed to calculate the pollutant loading rate through the overlaying of land-use and watershed map after the construction of new land-use map using the land register database with most exact land use classification. Application result for Chuncheon City shows that the proposed system results in one percent land use error while the statistical method results in five percent. More exact nonpoint source pollutant loading was estimated from this system.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.4
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• pp.189-196
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• 2020

In this study, two full-scale gravity load-designed reinforced concrete corner beam-column joints were tested by being subjected to uniand bi-directional cyclic lateral loading. The test variable was loading type: uni- or bi-directional loading. To investigate the effect of the loading type on the cyclic behavior of joint specimens, damage progression, force-deformation relation, contribution of joint deformation to total drift, joint stress-strain response, and cumulative energy dissipation were investigated. The test data suggest that bidirectional loading can amplify damage accumulation in the joint region.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.365-369
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• 1993

The reliability assessment of a simple porbabilistic fatigue analysis under random loading is proposed. Using the crack closure concept, the crack opening stress is assumed to be constant during random loading. The available loading history and test data are used for the comparison with the results of the reliability assessment of probabilistic fatigue analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.167-176
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• 2010

Managing the growing number of data generated through various processes requires the aid of Database Management System (DBMS) to efficiently handle the huge amount of data. These data can be inserted into database m real time or in batch, that come from multiple sources, including those that are coming from inside and outside of a network. The insertion of large amount of data is commonly done through specific bulk loading or insertion function supplied by each individual DBMS. In this paper, we analyze and evaluate on handling data bulk loading for heterogeneous systems that is organised as multi-tiered architecture and compare the result of DBMS bulk loader against program insertion from a software development perspective. We propose a hybrid solution using staging database that can be easily deployed for enhancing bulk loading performance compared to insertion by application.