• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.1
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• pp.123-140
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• 1997

In this paper we consider closed flow line systems with samploing inspections. The total number of parts in the system is assumed to be N. The processings carried out of each station do not always meet the requirement of quality. Therefore, upon completion of its processing at each station, a part is inspected to determine whether the processings meet the requirement of quality or not. We assume that inspection are done on a random basis. If a part is found to be defective by an inspection, it is fed back to the apropriate station. Two different cases will be considered in this study : a three-station flow line system with infinite buffers and a two-station flow line system with finite buffers. For each case, we will develop an exact method to obtain the performance measures such as throughput, machinen utilization, average outgoing quality and manufacturing lead time. For the case of the two-station flow line system ith finite buffers, we will also develop an approximation method using a stage-aggregation technique. Then using buffers, we will also develop an approximation method using a stage-aggregation technique. Then using these results, we will try to find an optimal inspection policy which maximizes the expected net profit under a certain cost structure. Although we present the results only for the two or three station flow line system in this paper, the results obtained in this paper can be extended easily to the system which consists of more than two or three stations.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.397-406
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• 2000

This study presents an effective optimal technique to control quantitatively lateral drift for tall steel braced frames subject to horizontal loads. In this paper, the displacement sensitivity depending on behavior characteristics of steel braced frames is established, and also the approximation concept that has the generality of the mathematical programming and can efficiently solve large scale problems is introduced. Especially, the commercially available standard steel sections are used for the discrete selection of member sizes. Three types of 12-story braced frames and a 30-story braced framework are presented to illustrate the features of the quantitative lateral drift control technique proposed in this study.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.475-484
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• 2008

Nowadays, lots of data mining applications based on continuous and online real time are increasing by the rapid growth of the data processing technique. In order to do association rule mining in that application, we have to use new techniques to find the frequent itemsets. Most of the existing techniques to find the frequent itemsets should scan the total database repeatedly. But in the application based on the continuous and online real time, it is impossible to scan the total database repeatedly. We have to find the frequent itemsets with only one scan of the data interval for that kind of application. So in this paper we propose an approximation technique which finds the maximum size of the frequent itemsets and items included in the maximum size of the frequent itemsets for the processing of association rule mining.

• Journal of the Korea Computer Graphics Society
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• v.17 no.3
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• pp.33-42
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• 2011

We present a new technique for removing interior knots of parametric B-spline curves. An initial curve is constructed by continuous $L_{\infty}$ approximation proposed by Eck and Hadenfeld. We employ Hausdorff distance to measure the shape difference between the original curve and the initial one. The final curve is obtained by minimizing their Hausdorff distance. We demonstrate the effectiveness of our technique with experimental results on various types of planar and spatial curves.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.403-407
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• 2012

The purpose of this study is to find the optimum skirt size for a composite pressure vessel using optimum analysis technique. The size optimization for skirt shape of a composite pressure vessel was conducted using sub-problem approximation method and batch processing codes programmed by APDL(ANSYS Parametric Design Language). The thickness and length of skirt part were selected as design variables for the optimum analysis. The objective function and constraints were chosen as weight and displacement of skirt part, respectively. The numerical results showed that the weight of skirt of a composite pressure vessel would be saved by maximum 4.38% through the size optimization analysis for the skirt shape.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.1
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• pp.11-22
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• 2023

A radiating elements fault diagnosis method with simplified radiation pattern measurement procedure was presented for planar active phased array antenna system. For presenting the mentioned method, the technique for linear approximation based on the radiation characteristics of a planar array configuration and a technique for solving a unique solution problem that occur in process of diagnosing a fault in a radiating elements were presented. Based on the presented method and a genetic algorithm, experimental simulations were performed for radiating element defect diagnosis according to various planar active phased array antenna configurations. As a result, it was confirmed that the presented radiating element fault diagnosis method can be smoothly applied to planar active phased antennas having various configurations.

• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.383-392
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• 2010

Modelling financial phenomena with diffusion processes is frequently used technique. This study reviews the earlier researches on the approximation problem of transition densities of diffusion processes, which takes important roles in estimating diffusion processes, and consider the method to obtain the coefficients of series efficiently, in series approximation method of transition densities. We developed a new efficient algorithm to compute the coefficients which are represented by repeated Dynkin operator on Hermite polynomial.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.10
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• pp.779-787
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• 2016

A nonlinear control law for the quad-rotor of a low-complexity, global approximation-free from system uncertainties and external disturbances are described in this paper. The control law guarantees convergence to a small bounded error using a prescribed performance function. The stability of the proposed nonlinear control system is also proven by the Lyapunov stability theorem. The advantage of this technique is that it has a simpler form than any other nonlinear compensators and is applicable to any nonlinear systems without precise knowledge of the systems. In this paper, the proposed approach is applied to attitude/altitude control of a quad-rotor. Numerical simulations are performed to investigate the proposed nonlinear attitude control law by applying it to an uncertain quadcopter system with external disturbances.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.6
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• pp.1-8
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• 2005

The calculation of parameters of a process model is modified to find better sliding mode controller for a process. A design method by Camacho has such problems as chattering and overshoot due to the Taylor the approximation errors for the time delay term of the first order model. In this paper, a new design technique for a sliding mode controller is proposed by introducing the modified Pade approximation considering the weight factor. With the proposed method, the process response can be directly used to estimate the system parameters without any numerical processing.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.118-123
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• 2008

This paper proposes a frequency transfer function synthesis for approximating a high-order model with resonance to a low-order model in the frequency domain. The presented model approximation method is based on minimizing the error function weighted by the numerator polynomial of approximated models, which is used of the RLS(Recursive Least Square) technique to estimate the coefficient vector of approximated models. The proposed method provides better fitting in a low frequency and peak resonance. And an example is given to illustrate feasibilities of the suggested schemes.