• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.2
• /
• pp.138-145
• /
• 2014

The initial configuration for 95-seat passenger regional turboprop aircraft, the so called KC950, was designed to meet the market requirements. This paper prescribes the initial design based upon aircraft design guidelines and compared the competitive aircraft configurations after considering the related FAR 25 regulations. More specifically, results of design describe how to select the fuselage cross-sectional area, how to layout the cabin, and how to determine the overall shape and physical dimension of the fuselage. Sizing of wing and empennage areas is estimated using empirical equations and tail volume coefficients in this design. Some design guidelines to determine wing sweep angle, taper ratio, incidence angle and location are also introduced.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.164-171
• /
• 1999

An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.3 s.168
• /
• pp.146-153
• /
• 2005

In this paper, a multi-step optimization using genetic algorithm with variable penalty function is introduced to the structural design optimization of a grinding machine. The design problem, in this study, is to find out the optimum configuration and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously under several design constraints such as dimensional constraints, maximum deflection limit, safety criterion, and maximum vibration amplitude limit. The first step is shape optimization, in which the best structural configuration is found by getting rid of structural members that have no contributions to the design objectives from the given initial design configuration. The second and third steps are sizing optimization. The second design step gives a set of good design solutions having higher fitness for lightweight and minimum static compliance. Finally the best solution, which has minimum dynamic compliance and weight, is extracted from the good solution set. The proposed design optimization method was successfully applied to the structural design optimization of a grinding machine. After optimization, both static and dynamic compliances are reduced more than 58.4% compared with the initial design, which was designed empirically by experienced engineers. Moreover the weight of the optimized structure are also slightly reduced than before.

• Transactions of Materials Processing
• /
• v.9 no.4
• /
• pp.348-355
• /
• 2000

The backward tracing scheme(BWT) of the finite element method has been extended lot the design of sheet blank in three-dimensional deformation. Originally the scheme was developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform or initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. For the confirmation of the analytic result derived from the backward tracing simulations as well as forward loading simulations, a series of experiment were carried out. The experiments include the first trial sheet forming process with a rectangular blank, an improved process with a modified blank preform and the final process with an optimum blank resulted from the backward tracing scheme. The experiments show that the backward tracing scheme has been implemented successfully in blank design of sheet metal forming.

• International Journal of Aeronautical and Space Sciences
• /
• v.6 no.1
• /
• pp.89-96
• /
• 2005

Ducted fans have advantages in noise as well as operational safety aspects compared to conventional tail rotors and are used as an anti-torque system for various classes of helicopters. The final goal of this study is to develop a ducted fan anti-torque system which can replace conventional tail rotors of existing helicopters to achieve safety enhancement and low noise level. In this paper, a conceptual design process and the results are described. Initially, the design requirement and the design parameter characteristics are analysed, and then initial sizing and configuration design are performed. There are several configuration changes due to specific technical reasons in each case. Finally, the required power and the pitch link load are predicted as an initial estimation. The conceptual design technique for the ducted fan in this study can be easily applied to the design of other ducted fans such as the lift fan for unmanned aerial vehicle.

• Journal of the Korean Society of Systems Engineering
• /
• v.9 no.2
• /
• pp.83-90
• /
• 2013

Integrated aircraft synthesis process for rapid analysis and design is described in this paper. Data flow between different analysis fields is described in details. All the data are divided into several groups according to importance and source of the data. Analysis of design requirements and certification regulations is carried out to determine baseline configuration of an aircraft. Overall design process can be divided into initial sizing, conceptual and preliminary design phases. Basic data for conceptual design are obtained from initial sizing, CAD and geometry analysis. Basic data are required input for weight, aerodynamics and propulsion analyses. Results of this analysis are used for stability and control, performance, mission, and load analysis. Feasibility of design is verified based on analysis results of each discipline. Design optimization that involves integrated process for aircraft analysis is performed to determine optimum configuration of an aircraft on a conceptual design stage. The process presented in this paper was verified to be used for light aircraft design.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.12
• /
• pp.1613-1618
• /
• 2011

Analysis method for mechanism has been fully developed and relatively easy work compared to mechanism synthesis. Developing or creating a new mechanism for a given task is a creative job. In this case, a few theories are developed such as type synthesis. However, these methods are not sufficient for mechanism designers to sufficientely take into account alternative mechanism models during the initial phase of the mechanism design process. This paper presents the configuration design of mechanisms using graphical representation in the conceptual design stage. In this stage of kinematic synthesis, one needs to select mechanisms and configure appropriately to realize the desired motion of a machine. Graphical representation of mechanisms is proposed in this paper to help a designer to be highly creative and efficient in the initial design process. It is possible to easily design and analyze the mechanism of a machine by using this method.

• Journal of Ship and Ocean Technology
• /
• v.5 no.3
• /
• pp.27-35
• /
• 2001

In this research, hybrid method with case-based reasoning and rule-based reasoning is applied. Using case-based reasoning, design experts'experience and know-how are effectively represented in order to obtain a proper configuration of midship section in the initial ship design stage. Since there is not sufficient domain knowledge available to us, traditional case-adaptation algorithms cannot be applied to our problem, i.e., creating the configuration of midship section. Thus, new case-adaptation algorithms not requiring any domain knowledge are developed antral applied to our problem. Using the knowledge representation of DnV rules, rule-based reasoning can perform deductive inference in order to obtain the scantling of midship section efficiently. The results from the case-based reasoning and the rule-based reasoning are examined by comparing the results with various conventional methods. And the reasonability of our results is verified by comparing the results wish actual values from parent ship.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.03b
• /
• pp.45-48
• /
• 1999

A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracking simulation has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup produce without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach for decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.81-85
• /
• 2005

In this paper, the structural design optimization of a wafer grinding machine using a multi-step optimization with genetic algorithm is presented. The design problem, in this study, is to find out the optimum configuration and dimensions of structural members which minimize the static compliance, the dynamic compliance, and the weight of the machine structure simultaneously under several design constraints. The first design step is shape optimization, in which the best structural configuration is found by getting rid of structural members that have no contributions to the design objectives from the given initial design configuration. The second and third steps are sizing optimization. The second design step gives a set of good design solutions having higher fitness for lightweight and minimum static compliance. Finally the best solution, which has minimum dynamic compliance and weight, is extracted among those good solution set. The proposed design optimization method was successfully applied to the structural design optimization of a high precision wafer grinding machine. After optimization, both static and dynamic compliances are reduced more than $92\%\;and\;93\%$ compared with the initial design, which was designed empirically by experienced engineers. Moreover the weight of the optimized structure are also slightly reduced than before.