• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.290-293
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• 1996

This paper presents an EMQ model which determines an optimal production run length in a deteriorating machine. It is assumed that a machine is subject to a random deterioration from an in-control state to an out-of-control state with an arbitrary distribution and thus producing constant proportion of defective items. An average cost function and an optimal production run length are determined. A mistake in previous model is found and discussed. A mistake in previous model is found and discussed. Numerical experiments are carried out to see the behavior of the proposed model depending on the cost factors as well as machine parameters, and some interesting behaviors are observed.

• 한국기계기술학회지
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• 제20권6호
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• pp.809-817
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• 2018

The model predictive controller performance of the mobile robot is set to an arbitrary value because it is difficult to select an accurate value with respect to the controller parameter. The general model predictive control uses a quadratic cost function to minimize the difference between the reference tracking error and the predicted trajectory error of the actual robot. In this study, we construct a predictive controller by transforming it into a quadratic programming problem considering velocity and acceleration constraints. The control parameters of the predictive controller, which determines the control performance of the mobile robot, are used a simple weighting matrix Q, R without the reference model matrix $A_r$ by applying a quadratic cost function from which the reference tracking error vector is removed. Therefore, we designed the predictive controller 1 and 2 of the mobile robot considering the constraints, and optimized the controller parameters of the predictive controller using a genetic algorithm with excellent optimization capability.

• Smart Structures and Systems
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• 제15권4호
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• pp.1041-1062
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• 2015

In this paper a method of finding optimal positions for piezoelectric actuators and sensors on different structures is presented. The genetic algorithm and multi-objective genetic algorithm are selected for optimization and $H_{\infty}$ norm is defined as a cost function for the optimization process. To optimize the placement concerning the selected modes simultaneously, the multi-objective genetic algorithm is used. The optimization is investigated for two different structures: a cantilever beam and a simply supported plate. Vibrating structures are controlled in a closed loop with feedback gains, which are obtained using optimal LQ control strategy. Finally, output of a structure with optimized placement is compared with the output of the structure with an arbitrary, non-optimal placement of piezoelectric patches.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.89-97
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• 2006

This paper presents a novel approach for non-iterative surface smoothing with feature preservation on arbitrary meshes. Laplacian operator is performed in a global way over the mesh. The surface smoothing is formulated as a quadratic optimization problem, which is easily solved by a sparse linear system. The cost function to be optimized penalizes deviations from the global Laplacian operator while maintaining the overall shape of the original mesh. The features of the original mesh can be preserved by adding feature constraints and barycenter constraints in the system. Our approach is simple and fast, and does not cause surface shrinkage and distortion. Many experimental results are presented to show the applicability and flexibility of the approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.159-162
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• 1993

A new approach using fuzzy dynamic programming is proposed for the flexible long-term generation mix under uncertain circumstances. A characteristic feature of the presented approach is that not only fuzziness in fuel and construction cost. load growth and reliability but also many constraints of generation mix can easily be taken into account by using fuzzy dynamic programming. The method can accommodate arbitrary shape of membership function as well as the operation of pump-generator. And so more realistic solution can be obtained. The effectiveness of the proposed approach is demonstrated by the best generation mix problem of KEPCO-system which contains nuclear, coal, LNG, oil and pump-generator hydro plant in multi-years.

• 대한교통학회지
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• 제23권6호
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• pp.7-18
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• 2005

현재 우리나라의 설계속도는 도로의 기능, 지역특성, 지형에 의해 결정하도록 규정하고 있다. 그러나 도로의 기능을 구분하는 뚜렷한 기준이 없어 적정 설계속도 결정에 설계자의 주관이 개입될 여지가 많으며, 기능분류가 단순하여 설계에 반영되지 못하는 도로기능이 존재하고, 지역분류기준 또한 모호하여 주변지역의 토지이용 특성을 제대로 반영하지 못하였다. 한편 도로가 통과하는 지역의 지형적 특성을 충분히 고려치 않고 단순히 교통소통 만을 강조하여 지나치게 높은 설계속도로 설계하여 도로의 건설비가 증가하고 있다. 따라서 본 연구에서는 지방부 도로 기능분류 및 설계속도 결정에 계획교통량 규모를 반영토록 하여 설계자의 주관적 판단소지를 줄이고 경제적 효율성을 기하였으며, 도시부 기능을 세분화하여 기능분류의 단순함과 설계에 반영되지 못하는 도로의 기능이 존재하는 문제를 해결하였다. 또한 GIS의 지형고도 데이터를 이용하여 지형을 구분하는 구체적 기준을 제시하였다. 즉 기능, 지역, 지형요소를 보다 세분하여 고려하고, 보완기준으로 계획교통량을 추가한 새로운 기능분류와 설계속도 결정기준을 제시하였다.

• 센서학회지
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• 제6권2호
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• pp.145-154
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• 1997

회로 시뮬레이션과 국부적 탐색을 갖는 시뮬레이티드 아닐링을 사용한 새로운 탐색 전략에 기초하여 고성능 연산 증폭기의 설계 자동화를 위한 기법을 제안하였다. 임의의 연산 증폭기 구조와 성능 규격에 대해서, 이산 설계 변수들을 갖는 비용 함수의 이산 최적화를 통해 연산 증폭기의 설계가 이루어진다. 설계 시간의 단축을 위해서 전용 회로 시뮬레이터와 몇 가지 휴리스틱을 사용하였다. 스마트 센서와 10 비트 25 MS/s 파이프라인 A/D 변환기에 사용 가능한 저전력 고속 전차동 CMOS 연산 증폭기의 설계를 통해서, 제안된 기법을 사용하여 개발된 설계 도구는 적은 설계 지식과 설계 노력을 가지고 고성능 연산 증폭기를 설계하는데 사용될 수 있음을 보였다.

• Current Optics and Photonics
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• 제6권2호
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• pp.161-170
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• 2022

Three-dimensional (3D) geometric models are introduced to correct vignetting, and a downhill simplex search is applied to determine the coefficients of a 3D model used in digital microscopy. Vignetting is nonuniform illuminance with a geometric regularity on a two-dimensional (2D) image plane, which allows the illuminance distribution to be estimated using 3D models. The 3D models are defined using generalized polynomials and arbitrary coefficients. Because the 3D models are nonlinear, their coefficients are determined using a simplex search. The cost function of the simplex search is defined to minimize the error between the 3D model and the reference image of a standard white board. The conventional and proposed methods for correcting the vignetting are used in experiments on four inspection systems based on machine vision and microscopy. The methods are investigated using various performance indices, including the coefficient of determination, the mean absolute error, and the uniformity after correction. The proposed method is intuitive and shows performance similar to the conventional approach, using a smaller number of coefficients.

• Journal of Biosystems Engineering
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• 제16권1호
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• pp.60-82
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• 1991

Drying process of red pepper is very important in terms of drying cost and quality of the end product. Recently, many studies on red pepper drying have been performed. Nevertheless, an optimum drying condition is not established yet. Drying characteristics of red pepper is much affected by drying factors such as variety and initial state of red pepper as well as by environmental drying factors such as temperature and relative humidity of drying air. Various varieties of red pepper are being cultivated and the initial state of red pepper at harvest is very ambiguous. For this reason, it is very costly and time-consuming to establish an optimum drying condition of red pepper by experiment. A general drying model to descirbe a drying process has not been developed due to diversity of drying characteristics of red pepper. This study was, therefore, performed to develop a general drying model describing a drying process of red pepper. The results from this study are summarized as follows. 1. A basic model was established to develop an appropriate mositure content model and temperature model describing a drying process of red pepper, and the basic model was validated with experimental data. 2. The bone dry weight of fruit and mositure content were accepted satisfactorily as parameter to define the arbitrary red pepper. 3. The equilibrium moisture content of red pepper was found out to be different according to the variety of red pepper, air temperature and relative humidity. Also, the EMC model was developed using the parameters of air temperature, relative humidity and bone dry weight of fruit. 4. A general drying model for red pepper was developed, parameters of which were expressed as the function of drying factors related with drying phenomena. The developed drying model was found out to describe well the drying process of red pepper.

• Structural Engineering and Mechanics
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• 제71권4호
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• pp.391-405
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• 2019

Compared to the ambient vibration test mainly identifying the structural modal parameters, such as frequency, damping and mode shapes, the impact testing, which benefits from measuring both impacting forces and structural responses, has the merit to identify not only the structural modal parameters but also more detailed structural parameters, in particular flexibility. However, in traditional impact tests, an impacting hammer or artificial excitation device is employed, which restricts the efficiency of tests on various bridge structures. To resolve this problem, we propose a new method whereby a moving vehicle is taken as a continuous exciter and develop a corresponding flexibility identification theory, in which the continuous wheel forces induced by the moving vehicle is considered as structural input and the acceleration response of the bridge as the output, thus a structural flexibility matrix can be identified and then structural deflections of the bridge under arbitrary static loads can be predicted. The proposed method is more convenient, time-saving and cost-effective compared with traditional impact tests. However, because the proposed test produces a spatially continuous force while classical impact forces are spatially discrete, a new flexibility identification theory is required, and a novel structural identification method involving with equivalent load distribution, the enhanced Frequency Response Function (eFRFs) construction and modal scaling factor identification is proposed to make use of the continuous excitation force to identify the basic modal parameters as well as the structural flexibility. Laboratory and numerical examples are given, which validate the effectiveness of the proposed method. Furthermore, parametric analysis including road roughness, vehicle speed, vehicle weight, vehicle's stiffness and damping are conducted and the results obtained demonstrate that the developed method has strong robustness except that the relative error increases with the increase of measurement noise.