• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.278-282
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• 2003

There is a strong industrial demands for the development of light-vehicle to improve fuel efficiency. It is more effective to reduce weight of the parts directly driven by an automobile engine. So the saving in weight of wheels which is operated by an automobile engine improve fuel efficiency more than other parts. There are many step of sheet metal forming in fabricating automotive wheel, so that it is difficult to design process and tools of multi-stage stamping. Traditionally, design process and tools have depended on the experience of skilled workers and it has done by trial and error methods. However, it needs too much costs and time. Taguchi methods has an advantage of the number of required experiments and reliability compared with trial and error method. In this study, Taguchi methods and response surface methods are applied to design process and tools of automotive wheel. As a result, the principal variables are selected and process conditions are optimized.

• The Korean Journal of Applied Statistics
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• v.25 no.4
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• pp.575-587
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• 2012

The effect of a new treatment is proven through the comparison of a new treatment with placebo; however, the number of parent non-inferiority trials tends to grow proportionally to the number of active controls. In a non-inferiority trial a new treatment is approved by proof that the new treatment is not inferior to an active control; however, both additional assumptions and historical trials are needed to show (through the comparison of the new treatment with the active control in a non-inferiority trial) that the new treatment is more efficacious than a putative placebo. The two different methods of using the historical data: frequentist principle method and meta-analytic method. This paper discusses the statistical methods and different Type I error rates obtained through the different methods employed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.27-38
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• 2006

The storage function model (SFM) has been used for the flood forecasting in Korea. The SFM has a simple calculation process and it is known that the model is more reasonable than linear model because it considers non-linearity of flood runoff. However, the determination of parameters is very difficult. In general, the trial and error method which is an manual calibration by the decision of a model manager. This study calibrated the parameters by the trial and error method and optimization technique. The calibrated parameters were compared with the representative parameters which are used in the Flood Control Centers in Korea. Also, the evaluation indexes on objective functions and calibration methods for the comparative analysis of simulation efficiency. As a result, the Genetic Algorithm showed the smallest variation in objective functions and, in this study, it is known that the objective function of SSR (Sum of Squared of Residual) is the best one for the flood forecasting.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.5
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• pp.422-428
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• 1988

An iterative learning control system is a control system which makes system outputs follow desired outputs by iterating its trials over a finite time interval. In a discrete time system, we proposed one method in which present control inputs can be obtained by a linear combination of the input sequence and time-shifted error sequence at previous trial. In contrast with a continous time learning control system which needs differential opreration of an error signal, the time shift operation of the error sequence is simpler in a computer control system and its effectiveness is shown by a simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.8
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• pp.678-684
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• 2008

A general treatment is to restore abfraction lesions with dental filler materials to reduce stress concentration. A material should be selected from various dental products based on long term experiences of dentist or personal preference concerning filler methods. A quantitative criterion is necessary to make an evaluation of the results as dentists decide treatment methods and dental materials relying on their clinical experiences. The purpose of this study is to find an optimal restoration method and material for noncarious cervical lesions using the finite element method. An objective function was defined to minimize the sum of tension or compression stress. Trial-and-error and approximation were used to find an optimal restoration method. An optimal solution was to fill TetricFlow inside the lesion and Z100 in the remaining region. The most desirable thickness ratio of the two filler materials was 0.125 with trial-and-error and it was similar to the results of approximation, 0.121 and 0.132.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.803-806
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• 2008

LEACHN is the computer simulation model which can be used to simulate field-scale N transformations and movement and has three organic pools (plant residue, manure, and soil humus), three inorganic pools (urea, nitrate and ammonium) and plant. Pot experiment operated May to October in 2004. LEACHN simulated the nitrogen movement and transformation in soil using method of PEST and trial and error.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.992-994
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• 1995

FLC has a good performance for complication system or unknown model by using human linguistic method but many part control design are based on expert knowledge or trial-error method and it is difficult to prove stability and robustness of controller. In this paper we improve this problem by setting fuzzy rules by dividing phase plane of error and rate of error change by switching surface. We can guarantee the stability in nonlinear system, and also in fuzzy PID type controller the complexity of controller design is increased by increasing the number of input variables and defining more range of operation if we want performance of more specific rules, thus we need to fine the method to decrease the number of control rules used in FLC design. In this paper the algorithm is validated by simulation using conventional FLC and proposed method.

• Architectural research
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• v.8 no.2
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• pp.43-48
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• 2006

The appropriate fleet estimation of the excavation equipment is a major factor in the determination of the cost and time requirements of a project. But the decision of what kind of equipment selected is often based on heuristic methods or trial and error in Korea. Thus, this study proposes a prototype model that uses genetic algorithms to select fleet estimation of loaders (backhoe) and trucks used in excavation work. To verify the applicability of this model, the case study was performed. And the result of the genetic model was compared with that of the trial & error method. The use of the genetic model suggested this study required 44days, 2 units of backhoes, 7 units of trucks, and a total cost of 171,839,756 won. With the estimated fleet number of equipment, the minimum cost of excavation work can be calculated, taking account of the time-cost trade-off. By utilizing this prototype model, the efficiency of excavation work can be improved.

• Journal of the Korea Society of Computer and Information
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• v.7 no.1
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• pp.62-67
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• 2002

Construction of automated terminal is urgently demanded to gain the foundation of hub-port in north east Asia. Therefore I suggest an adequate operating system model of automated terminal in Korea. In this paper the aim of automated terminal operating system is satisfied, four basic models are divided according to moving course of export and import cargo of each automated equipments, several input data are changed and analyzed dynamically by Trial and Error method, and then an optimized operating system model is designed. It is a Premise that all the yard equipments described in this paper must be automatic except quay crane.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.424-428
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• 2016

This paper presents the kinematics of a walking robot leg based on Jansen mechanism. By using simple mathematics, all trajectories of walking robot leg links can be calculated. A foot point trajectory is used to evaluate the performance of a walking robot leg. Trial and Error method is used to find a best combination of link lengths under certain restrictions. All simulations are performed by Matlab. Ground score, drag score, step size, foot lift, instant speed, and average speed of foot point trajectories are used for selecting the best one.