• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1995.10b
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• pp.131-138
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• 1995

A new technique using integer programming based on fuzzy multi-criteria function is proposed for generator maintenance scheduling. Minimization maintenance delay cost and maximization reserve power are considered for fuzzy multi-criteria function. To obtain an optimal solution for generator maintenance scheduling under fuzzy environment, fuzzy multi-criteria integer programming is used. In the maintenance scheduling, a characteristic feature of the presented approach is that the crisp constraints with uncertainty can be taken into account by using fuzzy set theory and so more flexible solution can be obtained. The effectiveness of the proposed approach is demonstrated by the simulation results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.197-202
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• 2005

In this paper, we analyzed the signal distortion incorporating meander-shaped transmission line on PCB in broadband frequency range, up to 50GHz. This broadband characteristic provides reasonable analysis of digital pulse having very short rising time. Simulation results reveal suppression characteristic at multiband which is dependent on only the width of meander arm. This width of arm also can be adjusted using different permittivity because it provides different effective wave-length. It is found that the suppression characteristic shows sharpness with as a function of the number of arms. However, these characteristics shown limitation for microstrip line structure rather than for stripline structure, so we can avoid these unwanted phenomena using stripline structure.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.799-804
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• 2004

Dynamic characteristic of CD/DVD deck for vehicle is analyzed in this paper. Generally CD/DVD deck for vehicle is used from inferior environment with the vibration of the vehicle and shock of outside and so on. Therefore it must have the structure which is stabilized from the vibration to prevent read error. For this purpose, vibration characteristic of the deck for vehicle should be identified. To analyze characteristic of the deck system, we perform the signal analysis and modal testing using the FFT analyzer. Also we change the design factor degrading the performance of the deck system and verify the efficiency improvement using the acceleration measurement occurring to the sound discontinuation.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.642-645
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• 2008

A pin fin with variable fin base thickness is analysed by using the one dimensional analytic method. Heat loss and fin thermal resistance are presented as a function of the fin base thickness, pin fin outer radius and convection characteristic numbers ratio. The relationship between the fin outer radius and fin base thickness for the same amount of heat loss is shown. One of the results indicates the fin thermal resistance decreases as the fin outer radius and/or convection characteristic numbers ratio increase whereas the fin thermal resistance is independent on the variation of fin base thickness.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1715-1723
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• 2016

We study the characteristic Jacobi operator ${\ell}={\bar{R}({\cdot},{\xi}){\xi}$ (along the Reeb flow ${\xi}$) on the unit tangent sphere bundle $T_1M$ over a Riemannian manifold ($M^n$, g). We prove that if ${\ell}$ is pseudo-parallel, i.e., ${\bar{R}{\cdot}{\ell}=L{\mathcal{Q}}({\bar{g}},{\ell})$, by a non-positive function L, then M is locally flat. Moreover, when L is a constant and $n{\neq}16$, M is of constant curvature 0 or 1.

• Journal of Korean Society for Quality Management
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• v.22 no.1
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• pp.122-132
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• 1994

So far, the Taguchi Method has dealt with multiple quality characteristics under the assumption that they are independent. Since the relationships between quality characteristics are practically important, this study proposes a new performance measure considering the correlation among characteristics. In this paper, we impose weight on each characteristic and correlation among characteristics. The loss function of multiple characteristics is defined in accordance with combination of simple characteristic types, and it is divided into terms of loss that characteristic itself and the correlation among characteristics cause. And the proposed method uses the expected loss of multiple characteristics as the new performance measure. The data in literature are used to compare with the existing performance measures.

• Communications for Statistical Applications and Methods
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• v.8 no.2
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• pp.383-394
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• 2001

This paper is a generalization of single and two-level skip-lot sampling plans to n-level. On every skipping inspection of the n-level skip-lot sampling plan, not only the number of consecutive lots to be accepted but also the fraction of lots to be inspected can be freely choosed. The general formulas of the operating characteristic function, average fraction inspected, average sample number and average outgoing quality in n-level skip-lot sampling plan are derived. The operating characteristic curves, average sample number and average outgoing quality of a reference plan, two-level and five-level skip-lot sampling plans are compared.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1624-1632
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• 2009

In this study, we introduce the design methodology of an optimized Interval Type-2 fuzzy controller. The fixed MF design of type-1 based FLC leads to the difficulty of rule-based control design for representing the linguistically uncertain expression. In the Type-2 FLC as the expanded type of Type-1 FLC, we can effectively improve the control characteristic by using the footprint of uncertainty(FOU) of membership function. Type-2 FLC has a robust characteristic in the unknown system with unspecific noise when compared with Type-1 FLC. Through computer simulation as well as practical experiment, we compare their performance by applying both the optimized Type-1 and Type-2 fuzzy cascade controllers to ball and beam system. To evaluate each controller performance, we consider controller characteristic parameters such as maximum overshoot, delay time, rise time, settling time and steady-state error.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1250-1256
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• 1995

In this paper, shielded suspended coplanar waveguide with multiple anisotropic substrates is analyzed by the point matching method in the quasi-TEM mode appoximation. The characteristic impedance and the effective dielectric constant are calculated by varying the width of center strip and gap between the center strip and the ground strip. And also the characteristic parameters are calculated as a function of ${\varepsilon}_{x}/{\varepsilon}_{y}$) and a permitivity of the support substrate. Approaching the ground strip to infinity, the values of the characteristic parameters are found to be in good agreement with the other results by variational method.

• Journal of Korean Society for Quality Management
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• v.23 no.3
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• pp.20-32
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• 1995

This paper is concerned with the economic selection of both the lower limit and the process mean for a continuous production process. Consider a production process where items are produced continuously. All of the items are subject to acceptance inspection. The items for which the measured values of the quality characteristic are larger than the lower limit are accepted, and those smaller than the lower limit are rejected and excluded from shipment. The process mean may be set higher to reduce the costs incurred by imperfect quality. Using a higher process mean, however, results in a higher production cost when production cost is an increasing function of the quality characteristic. Assuming that the quality characteristic is normally distributed with known variability, cost models are constructed which involve production cost, cost incurred by imperfect quality, rejection cost, and inspection cost. Methods of finding optimal values of the lower limit and the process mean are presented and numerical examples are given.