• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.105-113
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• 2005

In this paper, through the implementation of the application service, we evaluated the feasibility and availability of the staged application service platform, which is based on the sharing of the PVM cluster. Application service platform provides three managers for dividing the request processing steps into two stages, such as a request processing stage and a service providing stage. Three managers and its relation to the divided stages are as follows, service manager and load manager to distribute the request in front-end server for a request processing stage, job manager in clustered(back-end) servers for a service providing stage. The experiment shows that the staged application service platform provides more stable and scalable characteristics and better performance improvement on the dynamic load changes than the single server system. And also it shows that real application service system can be implemented easily without modification of the proposed service platform.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.103-109
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• 2002

The paper investigates the change of frequency response characteristics on two-stage gear reduction servo system according to the variation of backlash amount of each gear reduction stage, under the condition that the backlash of total system is constant. It is shown that the frequency response characteristics of the system heavily depend on the contribution ratio which is defined as a ratio of the first backlash amount to the total backlash. It is also found that there is an optimal backlash combination to maximize the bandwidth of two-stage gear reduction servo system when the allowable total backlash is determined.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.513-523
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• 2022

The purpose of settlement management when treating soft ground through preloading is to determine the amount of settlement, check the progression of consolidation, and compare the settlement with the target settlement amount. Of the various methods available for predicting settlement based on measured data, the hyperbolic method was used in this study to analyze the settlement behavior of soft ground considering the creep behavior resulting from staged fill. Two versions of the method were used: the existing hyperbolic method, and a modified hyperbolic method. The existing hyperbolic method predicts the settlement amount using data for the final settlement section only during soft ground treatment through staged fill, for which the coefficient of consolidation behavior (k) was computed to give a predicted final consolidation settlement amount of S_r = 1.05 cm. In comparison, using the modified method, a predicted final consolidation settlement of S_r = 0.50 cm is obtained by considering the data for each staged fill section. These results show that the modified method considering data from the staged settlement was more accurate than the existing method considering data only from the final settlement section. This modification to the hyperbolic method therefore represents an improvement in performance over the existing method.

• Journal of Korean Foot and Ankle Society
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• v.23 no.3
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• pp.110-115
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• 2019

Purpose: This study analyzed the clinical and radiological results of Reudi-Allgower type II and III open tibia pilon fracture patients who underwent plate fixation after the recovery of a soft tissue injury after external fixation. Materials and Methods: From 2010 to 2015, this study analyzed 14 patients who were treated for open tibial pilon fractures and could be followed up at least one year. The mean age was 49 years and the average follow-up period was 19 months. An emergency operation was performed for external fixation and open wounds, and secondary surgery was performed for definitive fixation using a plate. The radiological and clinical evaluations were analyzed retrospectively. Complications, such as post-traumatic osteoarthritis and wound infections were also analyzed. Results: The mean duration between two-staged surgery was 21 days and the mean bone union time was 9.2 months. Three cases of delayed union and one case of nonunion were reported. The malunion did not occur in all cases. The average American Orthopaedic Foot and Ankle Society (AOFAS) score was 68 points. A limitation of the ankle motion occurred in all cases. In four cases, wound infections due to initial open wounds occurred; one patient underwent a below the knee amputation due to chronic osteomyelitis. Post-traumatic arthritis occurred in 10 cases. Conclusion: Severe comminuted tibial plateau open fractures of Reudi-Allgower type II and III, which are high-energy injuries that result in extensive soft tissue damage, have a higher incidence of complications, such as ulcer problems and osteomyelitis, than closed tibia plateau fractures. Post-traumatic arthritis is the most common complication of tibia plateau open fractures, and staged surgery is recommended because of the relatively satisfactory clinical results.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2747-2752
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• 2007

A numerical study has been performed on the flow past a two-staged orifice in a rectangular duct. The flow field including the recirculation region behind the orifice was investigated and the pressure drop was calculated. Water was used as a working fluid and the flow was treated as the turbulent flow, of which the Raynolds number was 6000. The main parameters for the pressure drop and the recirculation region were the orifice's inclined angle against the duct, the interval between two orifices, the shape of the orifice's hole having the same area, and the change of the hole position at the same interval. The variation of the flow field was investigated with each parameter. Consequently, it was found that the most dominant parameter influencing the drop of the pressure was the change of the hole position at the same interval between orifices. Especially when the interval between orifices was narrow and the relative position the holes was changed, its effect to the flow field was shown most drastically as a result of this study. The SIMPLER algorithm with FLUENT code was employed to analyze the flow field.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.249-256
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• 2002

A new optimization procedure with approximate reanalysis module, using the staged hybrid methods with substructuring, is proposed in is study. In this procedure, displacements are calculated with two step mixed procedures. First step is to introduce the conservative approximation, which is a hybrid form of the linear and reciprocal approximation, as local approximation. In the next step, it is combined with the global approximation by reduced basis approach. The quality of reanalyzed quantities can be greatly improved through these staged hybrid approximations, specially for large changes in the design. Overall procedures are based on substructuring scheme. Several numerical examples illustrate the validity and effectiveness of the proposed methods.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1116-1123
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• 2006

In this study, the effective method for reliability estimation is proposed using tow-staged kriging metamodel and genetic algorithm. Kriging metamodel can be determined by appropriate sampling range and the number of sampling points. The first kriging metamodel is made based on the proposed sampling points. The advanced f'=rst order reliability method is applied to the first kriging metamodel to determine the reliability and most probable failure point(MPFP) approximately. Then, the second kriging metamodel is constructed using additional sampling points near the MPFP. These points are selected using genetic algorithm that have the maximum mean squared error. The Monte-Carlo simulation is applied to the second kriging metamodel to estimate the reliability. The proposed method is applied to numerical examples and the results are almost equal to the reference reliability.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2000.11a
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• pp.417-426
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• 2000

This study suggests integrated neural network models for Interest rate forecasting using change-point detection, classifiers, and classification functions based on structural change. The proposed model is composed of three phases with tee-staged learning. The first phase is to detect successive and appropriate structural changes in interest rare dataset. The second phase is to forecast change-point group with classifiers (discriminant analysis, logistic regression, and backpropagation neural networks) and their. combined classification functions. The fecal phase is to forecast the interest rate with backpropagation neural networks. We propose some classification functions to overcome the problems of two-staged learning that cannot measure the performance of the first learning. Subsequently, we compare the structured models with a neural network model alone and, in addition, determine which of classifiers and classification functions can perform better. This article then examines the predictability of the proposed classification functions for interest rate forecasting using structural change.

• Computers and Concrete
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• v.24 no.2
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• pp.173-183
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• 2019

This study presents experimental and numerical results of prestressed concrete composite beams with different casting and stressing sequence. The beams were tested under three-point bending and it was found that prestressed concrete composite beams could not achieve monolith behavior due to interface slippage between two layers. The initial stress distribution due to different construction sequence has little effect on the maximum load of composite beams. The multi-step FE analyses could simulate different casting and stressing sequence thus correctly capturing the initial stress distribution induced by staged construction. Three contact algorithms were considered for interaction between concrete layers in the FE models namely tie constraint, cohesive contact and surface-to-surface contact. It was found that both cohesive contact and surface-to-surface contact could simulate the interface slip even though each algorithm considers different shear transfer mechanism. The use of surface-to-surface contact for beams with more than 2 layers of concrete is not recommended as it underestimates the maximum load in this study.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.974-974
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• 1995