• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.203-210
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• 2005

Prototype model of MDU(Master Data Unit), to be employed on KSLV-I, has been developed and tested being interfaced with other units. Before stepping into the development of engineering and flight model phases, we have carried out reliability prediction of prototype MDU in order to assure availability of the unit. This paper describes the method of reliability prediction of prototype MDU and prediction results based on MIL-HDBK-217F, 'Electronic Reliability Design Handbook'.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.330-334
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• 2006

To maintain design-knowledge database and manage configuration for requirement of performance tests and safety standards of High Speed Railway(HSR), It is established that management system of performance tests and safety standards and then constructed that design-knowledge database and documented a performance test and safety specifications for supporting performance test and safety system using Model-Based Systems Engineering(MBSE) tool.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.369-375
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• 2006

Large eddy simulation has been applied to simulate turbulent flow around a cubic obstacle mounted on a channel surface for a Reynolds number of 40000(based on the incoming bulk velocity and the obstacle height) using a Smagorinsky model and a Lagrangian dynamic model. In order to develop the LES to the practical engineering application, the effect of upwind scheme, turbulent sub-grid scale model were investigated. The computed velocities. turbulence quantifies, separation and reattachment length were evaluated by compared with the previous experimental results.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.43-50
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• 2020

Many companies around the world are applying CMMI to improve the organization's ability to perform projects, and many others are pushing to obtain CMMI certification as more and more of them are offered as preconditions for participation in projects or supply product. Organizations with high maturity such as CMMI Level 4~5, analyze the accumulated R&D data of the organization and establish the performance management model so that R&D performance is continuously managed. So this paper shows the R&D performance management model made by LIGNex1 which is certificated with CMMI Level 5 organization and the case applied to the project, including its effectiveness.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.258-268
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• 2017

In this study, we aim to converge a technology for analyzing the hydraulic circuit of a loading arm with an- other one for analyzing multi-body dynamics by utilizing analysis software SimulationX. Further, this study intends to overcome the limitations of the existing technology for analyzing a hydraulic circuit with a variation at the rotation center of the moving mass and the difficulty of incorporating the behavior in a gravity field. First, the specifications of the hydraulic circuit components were reflected in an analysis model to secure reliability. Hydraulic circuit modeling was then performed using a single analysis model with a verified reliability. Subsequently, the multi-body system (MBS) model of the loading arm was formed. Finally, the analysis model of the hydraulic circuit and the MBS model were converged to check if the circuit analysis result was exactly reflected in the MBS model. The convergence analysis model has development cost-saving effect because it is capable of predicting the dynamic behavior of an object without the prototype.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.2
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• pp.9-22
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• 2021

A study on the sustainability evaluation of the requirements of the mobile industry closely related to the human factor was needed. We conducted the sustainability evaluation of the mobile industry using a quantitative evaluation method with the AHP tool and a qualitative evaluation method reflecting the technological age flow of the philosophical thoughts to improve the reliability of the evaluation results of the model verification. And this evaluation is to evaluate the consistency of the connection between the national sustainability and the mobile industry. In order to draw the conclusion of the relevance, the team member Delphi 5-point scale was used. As a result, the priority was confirmed in the national sustainable development indicator and mobile industry indicator. Quantitative and qualitative evaluation was applied to the discontinued model of mobile to derive insufficient indicators, and it was confirmed that if the indicators were improved and reflected, it would be sustainable. And in order to secure reliability and accuracy, we made a proposal to apply the systems engineering process to the development of the model evaluation field. The systems engineering technology process meets the needs and requirements of stakeholders throughout the lifecycle and it is suitable for the development model of the industry's sustainability assessment.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.221-239
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• 2022

Unknown geotechnical characteristics are key challenges in the design of piles for the plant, civil and building works. Although the N-values which were read through the standard penetration test are important, those N-values of the whole area are not likely acquired in common practice. In this study, the N-value is predicted by means of regression analysis with artificial intelligence (AI). Big data is important to improve learning performance of AI, so circular augmentation method is applied to build up the big data at the current study. The optimal model was chosen among applied AI algorithms, such as artificial neural network, decision tree and auto machine learning. To select optimal model among the above three AI algorithms is to minimize the margin of error. To evaluate the method, actual data and predicted data of six performed projects in Poland, Indonesia and Malaysia were compared. As a result of this study, the AI prediction of this method is proven to be reliable. Therefore, it is realized that the geotechnical characteristics of non-boring points were predictable and the optimal arrangement of structure could be achieved utilizing three dimensional N-value distribution map.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.173-181
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• 2007

Radiated emission / susceptibility performance of the KSLV-I 2nd stage which are controlled from the unit level to the system level should be examined and managed all over the frequency ranges in order to ensure the normal operation of the SC, the 1st stage of the KSLV-I, ground support equipments which are installed at the space center, and other wireless communication networks. Not only unintentional electric field emissions from the KSLV-I system and its subsystems should be restricted to the levels less than the limits specified in the EMC requirements, but also proper test and evaluation method should be established, respectively. In this paper, radiated emission/susceptibility test limits, method, and test results of the KSLV-I 2nd stage engineering model are presented.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.162-170
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• 2001

This paper presents a scheme for designing a fuzzy model-bsaed state observer for nonlinear system. For this scheme, a Tagaki-Sugeno type fuzzy model whose consequent part is of the state space form is obtained. In describes the locally linear input/output relationship of a system. The parameters of the fuzzy model are adjusted using a genetic algorithm. Then. fuzzy full-order and reduced-order state observers are designed based on the fuzzy model. A set of simulation works is carried out to demonstrate the effectiveness of the proposed scheme.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.94-103
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• 2000

This paper describes the model identification and the discrete-time sliding mode control of electro-hydraulic servo systems which are composed of servo valves, double-rod cylinder and load mass. The controlled plant is identified as a 3th-order discrete-time ARMAX model obtained from the prediction error algorithm, where a nominal model and modeling errors are zuantitatively constructed. The discrete sliding mode controller for 3th-order ARMAX model is designed in discrete-time domain, where all states are observed from Kalman filter. The discrete sliding mode controller has better tracking performance than that obtained from continuous-time sliding mode controller, in experiment.