• 소성∙가공
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• 제11권6호
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• pp.487-494
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• 2002

A new method of optimal blank shape design using the initial nodal velocity (INOV) has been proposed for the drawings of arbitrary shaped cups. With the given information of tool shape and the final product shape, corresponding initial blank shape has been found from the motion of boundary nodes. Although the sensitivity method, the past work of the present authors, has been proved to be excellent method to find optimal blank shapes, the method has a problem that a couple of deformation analysis is required at each design step and it also exhibits an abnormal behaviors in the rigid body rotation prevailing region. In the present method INOV, only a single deformation analysis per each design stage is required. Drawings of practical products as well as oil-pan, have been chosen as the examples. At every case the optimal blank shapes have been obtained only after a few times of modification without predetermined deformation path. The deformed shape with predicted optimal blank almost coincides with the target shape at every case. Through the investigation the INOV is found to be very effective in the arbitrary shaped drawing process design.

• 소성∙가공
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• 제29권5호
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• pp.272-281
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• 2020

As the thickness of mobile communication devices is getting thinner, the size of the internal parts is also getting smaller. Among them, the battery case requires a high-level deep drawing technique because it has a rectangular shape with a large aspect ratio. In this study, the initial blank shape was optimized to minimize earing in a multi-stage deep drawing process using an artificial neural network(ANN). There has been no reported case of applying artificial neural network technology to the initial blank optimal design for a square case with large aspect ratio. The training data for ANN were obtained though simulation, and the model reliability was verified by performing comparative study with regression model using random sample test and goodness-of-fit test. Finally, the optimal design of the initial blank shape was performed through the verified ANN model.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권2호
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• pp.96-103
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• 2010

A concept of preliminary design for mid-size superyachts is explored. First, the profile of a superyacht is interactively designed with the help of freeform curve functionality and graphical user interface (GUI) based interaction. The hull form is then constructed using major characteristic curves such as design waterline, deck sideline, and sections in addition to the predefined profile curve. After exterior hull modeling is done, the arrangement of significant interior spaces of all decks is carried out. A genetic algorithm is exploited to find a space arrangement by considering space fitness values, space proximity, and stairs connectivity of relevant spaces. A goal of the paper is to offer a step-by-step procedure for superyacht design from scratch or when initial information is not sufficient for complete design. For this purpose, a GUI based superyacht design system is developed. This design approach is expected to help users interactively design mid-size superyachts.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.171-175
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• 2005

Automotive parts manufacturers are doing their best to strengthen the competitiveness. They are developing a large variety of new manufacturing technologies to reduce the manufacturing cost. Combined One Body Stamping(C.O.B.S) is one of the remarkable technologies to reduce production cost. C.O.B.S makes possible to form several parts together in a process using only one die set while conventional stamping demands the same number of die sets to the number of parts. But the deformation mechanism in C.O.B.S is more complicated because the interactions between blanks. So the interaction effects should be considered in the stage of initial blank shape design. In the study, a blank design method to consider the interactions between blanks was proposed and verified through the simulations and experiments. A commercial incremental FE code, LS-Dyna, was used to simulate the C.O.B.S Process. And a reverse one step FE code, Hyper Form, was used to predict initial blank shape. The boundary conditions of the reverse one step FE analysis were determined by the proposed method.

• 전기학회논문지
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• 제61권12호
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• pp.1903-1910
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• 2012

This paper presents a data based low-order controller design algorithm for a linear time-invariant process with a time delay. The algorithm is composed by combining an identification step based on open loop pulse test with a low-order controller design step to obtain the entire set of controllers achieving multiple performance specifications. The initial information necessary for this algorithm are merely the width and amplitude of a rectangular pulse, a controller of four types (PI, PD, PID, first-order), and design objectives. Various parametric approaches that have been developed are merged in the controller design algorithm. The resulting controller set satisfying the design objectives are displayed on the 2D and 3D graphics and thus it is very easy for us to pick a controller inside the admissible set because we can check the corresponding closed-loop performances visually.

• Journal of Ship and Ocean Technology
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• 제9권3호
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• pp.23-32
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• 2005

Ship STEP(Standard for the Exchange of Product Model Data) which is composed of AP 215 (Ship Arrangement), AP 216(Ship Hull Form), AP 218 (Ship Structure), has been developed more than last 10 years and it is now at the stage just before IS(International Standard). It is expected that ship STEP would be used for the seamless data exchange among various CAD/CAM/CAE systems of shipbuilding process. In this paper the huge and complicated data structure of ship STEP is briefly reviewed at the level of ARM(Application Reference Model) and some abstract test cases which will be included as part of the standards are introduced. Basically ship STEP has common data model to be used without losing compatibility among those three different ship AP's, and it is defined as the modeling framework. Typical cases of data exchange during shipbuilding process, such as hull form data exchange between design office and model basin, midship structure data between shipbuilding yard and classification society are reviewed and STEP physical data are generated using commercial geometric modeling kernel. Test cases of ship arrangement at initial design stage and hydrodynamic data of crude oil carrier are also included.

• Educational Technology International
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• 제17권1호
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• pp.1-37
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• 2016

The purpose of this study was to develop a MOOC design model that would improve the current practice of MOOC development in Korea by specifying easy-to-use course development procedures and guiding strategies. Following Richey and Klein (2007)'s conceptual model development procedure, the first step was to perform critical review of relevant literature and observe typical MOOC development processes. As a result, the initial model was developed. The second step was to conduct the expert review with five educational technology and MOOC researchers to secure the internal validity of the model. Based on the experts' suggestions, the model was revised and once again reviewed by the same experts. This process resulted in the development of the 2^nd version of model. The third step was to carry out external validation research in order to test the effectiveness, efficiency, and usability of the model. A basic model may be confirmed or corrected based on examination of its results. Consequently, the model was elaborated as the final model. In the final model, 6 procedural phases and 9 specific steps were included. The six procedural phases are: Analysis (1st Iteration), Design, Development (Course Development), Implementation, Evaluation, and Analysis (2nd Iteration), a slight variation of ADDIE model. The specific steps include: 1) Goal Setting, 2) Environment Analysis, 3) Content Design, 4) Style Design, 5) Course Development, 6) Implementation Plan, 7) Course Implementation, 8) Summative Evaluation, and 9) Need Reflection. The study concluded with suggestions for further research and application of the MOOC design model.

• 산업공학
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• 제23권3호
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• pp.257-263
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• 2010

Taguchi defined a good quality as 'A correspondence of product characteristic's expected value to the objective value satisfying the minimum variance condition.' For his good quality, he suggested Taguchi Method which is called Robust design which is irrelevant to the effect of these noise factors. Taguchi Method which has many success examples and which is used by many manufacturing industry. But Optimal solution of Taguchi Method is one among the experiments which is not optimal area of experiment point. On the other hand, Response Surface Method (RSM) which has advantage to find optimal solution area experiments points by approximate polynomial regression. But Optimal of RSM is depended on initial point and RSM can not use many factors because of a great many experiment. In this paper, we combine the Taguchi Method and the Response Surface Method with each advantage which is called Taguchi-RSM. Taguchi-RSM has two step, first step to find first solution by Taguchi Method, second step to find optimal solution by RSM with initial point as first step solution. We give example using catapults.

• Journal of Power Electronics
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• 제16권4호
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• pp.1396-1406
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• 2016

A novel controller design is presented for the recently proposed electric springs (ESs). The dynamic modeling is analyzed first, and the initial Bode diagram is derived from the s-domain transfer function in the open loop. The design objective is set according to the characteristics of a minimum phase system. Step-by-step optimizations of the Bode diagram are provided to illustrate the proposed controller, the design of which is different from the classical multistage leading/lagging design. The final controller is the accumulation of the transfer function at each step. With the controller and the recently proposed δ control, the critical load voltage can be regulated to follow the desired waveform precisely while the fluctuations and distortions of the input voltage are passed to the non-critical loads. Frequency responses at any point can be modified in the Bode diagram. The results of the modeling and controller design are validated via simulations. Hardware and software designs are provided. A digital phase locked loop is realized with the platform of a digital signal processor. The effectiveness of the proposed control is also validated by experimental results.

• 대한기계학회논문집A
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• 제27권1호
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• pp.152-157
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• 2003

Process design of hot forging, asymmetric to symmetric rib-web shape steel, which is used for the turnout of railway express has been investigated. Owing to the big difference in shape between the initial billet and the final forged product, it is impossible to hot forge the rail in a single step. Therefore, multi step forging as well as die design for each step are necessary for the production. The deformation behavior during hot forging has been analyzed by the numerical simulation through commercial FEA software, $DEFORM^{TM}$-2D. Modification of the design and repeated simulation have been carried out on the basis of the simulation result. For comparison with the simulation results. flow analysis experiment using plasticine has been also carried out. The results of the flow analysis experiment showed good agreement with those of the simulation. Therefore, the developed process design could be applied to the actual production.