• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.129-130
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• 2011

2009 Presidential Council on National Competitiveness to plan trying to the advancement in the construction industry 'design and engineering of the global competitiveness' in the content of weak points of the design and engineering capabilities to secure the overall problem. In domestic technological of design and engineering behind the other building construction sector about 70%. Especially hindrance factor was founded between design ordering organization, design firm and subcontractor in working design stage. In this paper carried out to hindrance factor that decrease the efficiency in working design stage for a strategy to improve the utilization of basic data.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.36-44
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• 2007

This paper is focused on the optimum design for decreasing volume and increasing reliability of multi-stage gear drive. For the optimization on volume and reliability, multi-objective optimization is used. The genetic algorithm is introduced to multi-objective optimization method and it is used to develop the optimum design program using exterior penalty function method to solve the complicated subject conditions. A 5 staged gear drive(geared motor) is chosen to compare the result of developed optimum design method with the existing design. Each of the volume objective, reliability objective, and volume-reliability multi-objectives are performed and compared with existing design. As a result, optimum solutions are produced, which decrease volume and increase reliability. It is shown that the developed design method is good for multi-stage gear drive design.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.96-101
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• 2011

Korea Aerospace Research Institute is performing 3 stage transonic axial compressor development program. This paper introduces design step of the compressor, the performance test results and its analysis. In the fore part of the paper, aerodynamic process of the 3 stage axial compressor is presented. To satisfy both of the mass flow and pressure rise, the compressor should rotate at a high rotational speed. Therefore the transonic flow field forms in the rotor stages and it is designed with a relatively high pressure rise per stage to satisfy its design target. The compressor stage consists of 3 stages, and the bulk pressure ratio is 2.5. The first stage is burdened with the highest pressure ratio and less pressure rises occur in the following stages. Also it is designed that tip Mach number of the first rotor row does not exceed 1.3, while the maximum relative Mach number in the rotor stage is between 1.3~1.4 to increase the compressor flow coefficient. The final design has been confirmed by iterating three dimensional CFD calculations to verify design target and some design intentions. In the latter part of the paper, its performance test processes and results are presented. The performance test result shows that the overall compressor performance targets; pressure ratio and efficiency are well achieved. The stator static pressure distributions show that the blade loading is gradually increasing from the downstream of the compressor.

• Journal of the Korean Society of Safety
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• v.35 no.3
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• pp.24-31
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• 2020

The duty of construction clients in WSH (Workplace Safety and Health) system was included in the amendment of Occupational Safety and Health Act (enforced on 16 January 2020), which was estimated the shift of paradigm in the prevention of construction accidents. The purpose of this paper is to introduce the analysis results of construction clients' role in the construction project, which were performed by authors over the recent years in order to impose the duty on construction clients, and to suggest their role according the plan, design, and construction stage. Utilizing the systematic literature review process based on Meta analysis, the related papers were selected. For the selected papers, related domestic and foreign regulations, and other prominent report, the construction clients' role was analyzed by reflecting the experts' advice. Results show that the construction clients should control the designer and contractor for implementing the WHS system during the whole process of the construction project. They should supply sufficient source and time to ensure the workers' safety. In the plan stage, the key role of construction clients is to identify intensively controlled hazard and risk reduction plan and to transfer the results. In the design stage, their key role is to select the designer with the capacity in WSH and to assist the designer for the safety design. The main key role of construction clients in the costruction stage is to select the contractor with specialty in WSH including a contract reflecting the WSH requirement and to check implementation of WSH plan, WSH cost, WSH education, and accident report. In addition, it is thought that the construction clients' participations in the site WSH activity and adjustment of safety and health problem among contractors can be effect in the prevention of construction accidents.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.76-79
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• 2012

Satellite power system is critical for mission design and survival operation. Accordingly power conversion circuit has to stable design and verify for operation condition change (load, voltage, thermal condition). however, multi-stage make complicate for modeling and get all state solution. In this paper present all state solution for multi-stage converter by using Extended Describing Function(EDF) modelling. EDF modelling has merit to solve complex circuit but it has limit too. Because of fundamental approximation, EDF modeling is not match all topology. Consequently, we verify passible topology for EDF modeling and stable design multi-stage converter.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1438-1441
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• 2005

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In this system, measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100um\times{100um}$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. Using this AFM system, 3um pitch specimen was measured. As a result, the uncertainty of total system has been evaluated.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.585-595
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• 2008

Process design of multi-stage forging for a bolt with nonaxisymmetric washer cam has been studied by using finite element method. For shape complexity of the bolt, it is impossible to manufacture in a single stage forging. To design multi-stage forging for the bolt the forging load and fiber flow of each step have been analyzed by using commercial finite element code DEFORM-3D. Simulated results have been compared with experimental ones. Multi-stage forging process has been designed with four stages. The workpiece should be eccentric shape until third forging stage. And then bolt head and washer of eccentrical shape is created in last stage. As a results, It was predicted that shape of product would be good and effective strain would be uniformly distributed in the product. Also, it was predicted whether defects would exist or not by reviewing the fiber flow.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.16-24
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• 2012

In this study, two-stage hypersonic scramjet vehicle was designed for the flight condition of Mach number 6. In order to launch at sea level, two stage concept was applied. The first stage of the vehicle is solid rocket-powered and is mounted under the second stage. The second stage is powered by scramjet propulsion system and gas wings. The suggested mission scenario is to deliver 0.2 ton payload to the range of 2,000 km. For the first step of conceptual design, trajectory of air vehicle was calculated by 3-DOF trajectory code. Based on the result of trajectory code, scramjet engine design and mass estimation were performed by non-equilibrium nozzle flow code and NASA's HASA model, respectively. In order to find best solution, all steps of designing process was iterated until they was reached.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.309-317
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• 2011

In this study, two-stage hypersonic scramjet vehicle was designed for the flight condition of Mach number 6. In order to launch at sea level and Mach number 0, two stage concept was applied. The first stage of the vehicle is rocket-powered and is mounted under the second stage. The second stage is scramjet-powered propulsion system and has wing. The suggested mission scenario is to deliver 0.2 ton payload to the range less of 2000km. For the first step of conceptual design, trajectory of air vehicle was calculated by 3-DOF trajectory code. Based on the result of trajectory code, scramjet engine design and mass estimation were performed by non-equilibrium nozzle flow code and NASA's HASA model, respectively. In order to find best solution, all step of designing process was iterated until they were converged.