• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.123-132
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• 1995

During compression molding of fiber-reinforced polymeric composites, microstructural changes such as the fiber-matrix separation and the fiber orientation are occurred by the flow of composite materials. Since the nonhomogeneity and anisotropy of composites are caused by the separation and orientation of fibers. On the other hand, the separation and the orientation of fibers are inseparably related to each other. In this paper the degree of nonhomogeneity which is a measure of the separation is obtained using one-dimensional rectangular shaped part compression molding. And the orientation function is measured by the image processing using soft X-rayed photograph and image scanner. We study effects of the mold temperature on the degree of nonhomogeneity and the orientation function.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.64-69
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• 2001

In general, laminate effective orthotropic thermal conductivities are dependent on fiber and matrix material properties, fiber volume fraction and fabric geometric parameters. This paper deals with the predicting method of the transverse and the in-plane thermal conductivities of plain weave fabric composites based on the three dimensional series-parallel thermal resistance network. Thermal resistance network was applied to unit cell model that characterizes the periodically repeated pattern of plain weave. Also, an experiment apparatus is setup to measure the thermal conductivities of composite material. The numerical and experimental results of carbon/epoxy plain weave are compared.

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.127-132
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• 2007

위성영상 기술의 발달과 고해상도 위성영상의 해상도 규제가 완화됨에 따라 건물의 높이 정보를 획득하는데 있어 고해상도 위성영상의 그림자 정보를 이용하는 연구들이 활발히 수행되어지고 있다. 그림자 정보를 이용하여 건물 높이 정보를 획득하는 연구의 정확도를 높이기 위해서는 정확한 건물의 그림자 탐지가 선행되어야 한다. 따라서 본 논문에서는 단영상을 이용한 그림자 탐지기법인 임계값법(Thresholding), 영상분류법, 영역확장법(Region Growing)을 건물의 그림자 탐지에 적용하여 각 기법의 장단점과 정확도를 평가하였다. 영상에서 수동으로 건물의 그림자를 디지타이징한 참조 자료와 기법들을 적용하여 탐지한 결과 영상을 시각적으로 비교하였고, 오차행렬(Confusion Matrix)을 이용한 전체정확도(Accuracy), F-measure, AOR(Area Overlap Ratio)을 이용하여 정량적인 정확도평가를 수행하였다. 실험결과 영역확장법을 적용한 경우 시각적 정량적으로 가장 높은 정확도를 보였으며, 영상분류법을 적용한 경우 시각적으로는 임계값을 적용한 경우보다 좋은 결과를 보였으나 정량적으로는 가장 낮은 정확도를 보였다.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.957-962
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• 2008

We propose a model for the line expansion problem in the AMOLED (Active Matrix Organic Light Emitting Diodes) industry, which now faces market uncertainty: for example, changing customer needs, technological development path, etc. We focus on the optimal investment time and size of the AMOLED production lines. In particular, employed here is the ROV (Real Options Valuation) model to show how to capture the value of line expansion and to determine the optimal investment time. The ROV framework provides a systematic procedure to quantify an expected outcome of a flexible decision which is not possible in the frame of the traditional NPV (Net Present Value) approach. Furthermore, we also use Monte Carlo simulation to measure the uncertainty associated with the line expansion decision; Monte Carlo simulation estimates the volatility of a decision alternative. Lastly, we present a scenario planning to be conducted for what-if analysis of the ROV model.

• Communications for Statistical Applications and Methods
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• v.24 no.3
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• pp.317-324
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• 2017

An influence measure known as Cook's distance has been used for judging the influence of each observation on the least squares estimate of the parameter vector. The distance does not reflect the distributional property of the change in the least squares estimator of the regression coefficients due to case deletions: the distribution has a covariance matrix of rank one and thus it has a support set determined by a line in the multidimensional Euclidean space. As a result, the use of Cook's distance may fail to correctly provide information about influential observations, and we study some reasons for the failure. Three illustrative examples will be provided, in which the use of Cook's distance fails to give the right information about influential observations or it provides the right information about the most influential observation. We will seek some reasons for the wrong or right provision of information.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.487-493
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• 2004

This paper consider a six sigma project for improving the TIP life time in a spot welding process. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Nine key process input variables are selected by using C&E matrix and FMEA, and finally four vital few input variables are selected from analyze phase. The optimum process conditions of the four vital few input variables are jointly obtained by maximizing TIP life time using DOE.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1038-1041
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• 2004

In this study, developed a micro-level experimental setup to measure pore pressure and poroelastic modulus in various strain and strain rate about a stress in micro-structure of bone tissue. It is essential device in the development of the model to analysis the interstitial bone fluid flow of the lacuno-canalicular system to be known that would effect on the bone remodeling. The constitution of the experimental setup is as follows, microscopic image processing system; actuator control unit; load measurement system. A pilot study was used an artificial chemical wood to have similar poroelastic property of bone matrix and conducted to validate the suitability of the measurement system.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.7
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• pp.578-583
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• 2002

This paper presents a method for designing fuzzy $H_2/H_{\infty}$ controllers of nonlinear systems with time varying delay. Takagi-Sugeno fuzzy model is employed to represent nonlinear systems with time varying delay. Using a single quadratic Lyapunov function, the globally exponential stability and $H_2/H_{\infty}$ performance problem are discussed. A sufficient condition for the existence of fuzzy $H_2/H_{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMls). The proposed fuzzy $H_2/H_{\infty}$ controllers minimizes the upper bound on the linear quadratic performance measure.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.505-509
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• 2011

This paper attempts to classify known facial expressions and to establish the correlations between two regions (eye + eyebrows and mouth) in identifying the six prototypic expressions. Covariance is used to describe region texture that captures facial features for classification. The texture captured exhibit the pattern observed during the execution of particular expressions. Feature matching is done by simple distance measure between the probe and the modeled representations of eye and mouth components. We target JAFFE database in this experiment to validate our claim. A high classification rate is observed from the mouth component and the correlation between the two (eye and mouth) components. Eye component exhibits a lower classification rate if used independently.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.418-424
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• 2017

A wheel dynamometer was installed between the rim and axle hub to measure the forces and moments applied to a vehicle. The wheel dynamometer was composed of sensing and signal processing components. Because the sensing component contained a complex structure to sense the six components of the forces and moments and the wheel rotated along with the vehicle movement, sophisticated signal processing hardware and a software algorithm were used. The strains and the calibration matrices of the wheel dynamometer along the wheel rotation angle were investigated using FEM. From the analysis, the calibration matrices were simplified using a spline interpolation. Based upon these results, the signal processing component could be effectively designed and the firmware software could be simplified.