• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.35-44
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• 2020

Design techniques for the deep mixing method, one of the soft ground improvement methods, include two ways to interpret the ground as composite ground and pile ground. However, since comparative studies on these two approaches are insufficient, it is difficult to clearly define the analysis criteria in the design. In this study, two-dimensional and three-dimensional analyses have been performed with different conditions. The three conditions, the embankment height, depth of soft ground, and replacement ratio of reinforcement zones were varied and the analysis was performed on the basis of the assumption of composite ground and pile ground for each condition. As a result, the minimum depth of improvement in the two-dimensional analysis was deeper by 6.85~9.08% than in the three-dimensional analysis. The pile ground analysis showed that the depth of improvement was deeper by 12.22~14.45% than the composite ground analysis. Based on these results, it is concluded that for more accurate design, three-dimensional analysis should be performed rather than two-dimensional analysis. also, it is judged that necessary to analyze the ground as composite ground for economical design, and as the pile ground analysis for stable design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.651-657
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• 2023

Railroad alignment improvements and operating speed increase occupy considerable portion in recent railroad market. Developing countries have limitations to construction of new high speed railroads due to the burden of budgets and the lack of demands, and the projects of operating speed increase arepracticallyrecommended. Thisstudy developed the methodologyto provide the railroad alignment design alternatives and the costs by upgrading the "Intelligent Railroad Alignment Design Program (ei-Rail)" which has been used to obtain the alignment plans and construction costs for railroad construction projects. The program provides the cost for alignment improvement, design drafts and the effects of operating speed increase with the input of target improvement speed and the prevailing railroad alignment on the numerical map. It is then expected for the ei-Rail program to be used for the supporting tool for the railroad alignment improvement projects.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.57-65
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• 2009

An efficient and high-fidelity design approach for wing-body shape optimization is presented. Depending on the size of design space and the number of design of variable, aerodynamic shape optimization process is carried out via different optimization strategies at each design stage. In the first stage, global optimization techniques are applied to planform design with a few geometric design variables. In the second stage, local optimization techniques are used for wing surface design with a lot of design variables to maintain a sufficient design space with a high DOF (Degree of Freedom) geometric change. For global optimization, Kriging method in conjunction with Genetic Algorithm (GA) is used. Asearching algorithm of EI (Expected Improvement) points is introduced to enhance the quality of global optimization for the wing-planform design. For local optimization, a discrete adjoint method is adopted. By the successive combination of global and local optimization techniques, drag minimization is performed for a multi-body aircraft configuration while maintaining the baseline lift and the wing weight at the same time. Through the design process, performances of the test models are remarkably improved in comparison with the single stage design approach. The performance of the proposed design framework including wing planform design variables can be efficiently evaluated by the drag decomposition method, which can examine the improvement of various drag components, such as induced drag, wave drag, viscous drag and profile drag.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.37-46
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• 2018

Present research is to evaluate and improve the sealing performance of the duct cap assembly for the ice dispensers through structural analysis. The nonlinear contact problems to check the sealing performance were analyzed using ANSYS software. The results of the analyses related to the sealing performance: the displacement distribution, the contact condition between the cap-silicon and the case, and the pressure distribution on the contact surface, were examined and discussed. Based on the results of the existing design of the duct cap assembly, two cases of the design modifications to improve the sealing performance were introduced. By examining the results of the two cases, a final design improvement plan was proposed and analyzed. It is shown that the sealing performance of the proposed final design is much more favorable than the existing design. The method of structural analysis and design improvement of the duct cap assembly presented in this paper will help improve the sealing performance of the ice dispenser duct caps.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.87-94
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• 2023

This paper addresses the installation and modification design of airframe structures for new and modified equipment installations that are essential for aircraft performance improvement. Typical performance improvement equipment mounted on the exterior of the aircraft include antenna, radar, electro-optical/infrared (EO/IR), and self-protection system equipment, which require structural reinforcement, modification, and mounting design of the green aircraft for operation. In the interior of the aircraft, console and rack structures are modified or added according to user operation requirements. In addition, this is accompanied by the installation design of equipment to be replaced and added for performance improvement, and the according modification of environmental control system components for internal cooling. The engineering process and cases in which airworthiness was verified through the detailed design of airframe structures with structural integrity, operability, and maintainability of performance-improved aircraft are presented.

• Journal of Welding and Joining
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• v.24 no.2
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• pp.42-47
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• 2006

While it is known that the weld toe grinding method may give 3.4 times of fatigue strength improvement, this improvement may significantly vary according to weld bead shapes and loading modes. Although tremendous interest have been given in improving fatigue strength improvement for ship structures, quantitative results are yet in need. In this context, a series of fatigue tests is carried out for a type of test specimen that are typically found in ship structures. Weld burr grinding is carried out using a electric grinder in order to remove surface defects and improve the weld bead profile. The test results are compared with the same type of test specimen without applying the fatigue improvement technique in order to obtain a quantitative measure of the fatigue strength improvement. On the other hand, both hot spot stress and structural stress methods are employed to compare the effectiveness of the two methods in evaluating the fatigue strength improvement of welded structures.

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.05a
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• pp.148-149
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• 2003

• Journal of the Korean housing association
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• v.14 no.2
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• pp.1-7
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• 2003

The purpose of this study is to develop the urban design guidelines in detached housing areas for the improvement and management of residential townscape. Through a detail examination and analysis of the urban design guidelines and landscape regulations of U.S.A, Japan, and Korea to be applied to detached housing area for residential townscape, the urban design guidelines in detached housing area was derived. Urban design guidelines are composed of building guidelines, landscape guidelines, street guidelines, and sign guidelines. The municipality have to make regulations in detached housing area for the improvement and management of residential townscape based on this urban design guidelines.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.641-650
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• 2017

In order to include the design capability for a compound rotorcraft in a helicopter conceptual design and optimization framework, relevant further improvement was planned and conducted. Previously, a certain conceptual design optimization framework was developed by the present authors to design a modern rotorcraft with single main and tail rotor. The previously developed framework was further improved to expand its capability for a compound rotorcraft. Specifically, its power estimation algorithm was upgraded by using a comprehensive rotorcraft analysis program, CAMRAD II. The presently improved conceptual design and optimization framework was validated using data of the XH-59A aircraft.

• Journal of KIBIM
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• v.5 no.4
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• pp.37-46
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• 2015

In a construction project, collaboration amongst the project participants is a critical factor for high-quality results and successful completion of the project. Owing to the advance of information technologies, web-based systems have become more common in the construction industry, but research and development has been made for only limited areas. For organized and systematic collaboration in various fields, collaboration systems have to be developed in a holistic manner based on diverse needs from the whole construction industry. This study aims to investigate the current status of web-based collaboration systems from structural engineers' perspectives and propose an improvement plan. For a systematic analysis of selected cases, we apply a classification of three developmental stages depending on interoperability and organizational levels: structural design and analysis, collaborative design, and integrated design management. Thereafter, the characteristics of each stage are extracted and comparatively analyzed. Lastly, three functional factors were proposed for the improvement of web-based collaboration systems for structural design.