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Joung-Hahn Yoon,Young Chel Kwun,Jong Seo Park,Jin Han Park 한국지능시스템학회 2007 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.7 No.1
Balasubramaniam and Muralisankar (2004) proved the existence and uniqueness of fuzzy solutions for the semilinear fuzzy integrodifferential equations with nonlocal initial condition. Park et al. (2006) found the sufficient condition of this system. Recently, Kwun et al. (2006) proved the existence and uniqueness of solutions for the semilinear fuzzy integrodifferential equations with nonlocal initial conditions and forcing term with memory in EN. In this paper, we study the controllability for this system by using the concept of fuzzy number whose values are normal, convex, upper semicontinuous and compactly supported interval in EN.
Robust tool path generation for three-axis ball-end milling of sculptured surfaces
Joung-Hahn Yoon 한국산업응용수학회 2005 한국산업응용수학회 학술대회 논문집 Vol.- No.-
Tool path generation is the main issue in the finishing stage of NC machining. In order to satisfy surface finish quality, tool paths are generated so that the scallop height formed by two adjacent tool paths is controlled within a predefined machining tolerance. In order to fill this requirement, the path interval should be small enough, and consequently, the machining efficiency is limited. To achieve a significant improvement in machining efficiency, the scallop height is kept at a constant which is equal to the predefined machining tolerance. This constant scallop height machining was first proposed by Suresh and Yang [4]. Improvements on the preliminary work were later proposed by Lin and Koren [2] and Sarma and Dutta [3]. Several rough approximations were used in their algorithms, and consequently, the generated tool paths cannot guarantee that the scallop height is even within the predefined machining tolerance. To improve the machining accuracy of constant scallop height machining, Feng and Li [1] proposed an iterative approach for tool path generation using a thorough understanding of the machining geometry. In the iterative algorithm, it was utilized a function which indicates the distance to the design surface. The bisection method could be used because the distance function is continuous. The present author found that the distance function is also differentiable and analytic [5]. There-fore the bisection method could be superseded by the Newton method, and consequently, the total computing time is reduced. In the works of Feng and Li [1] and Yoon [5], the iterative algorithms need the explicit solution of the orthogonal projection to the design surface for a point. However, modern CAD/CAM systems fail to provide sufficiently robust method for the orthogonal projection. In this talk, I will suggest a new iterative approach for constant scallop height machining while avoiding the projection and therefore also improving the computational speed significantly. In order to avoid the point projection, it is proposed a new model denoted by effective cutting profile for the machined strip detection.
Yoon, Joung-Hahn,Kwun, Young-Chel,Park, Jong-Seo,Park, Jin-Han Korean Institute of Intelligent Systems 2007 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.7 No.1
Balasubramaniam and Muralisankar (2004) proved the existence and uniqueness of fuzzy solutions for the semilinear fuzzy integrodifferential equations with nonlocal initial condition. Park et al. (2006) found the sufficient condition of this system. Recently, Kwun et al. (2006) proved the existence and uniqueness of solutions for the semilinear fuzzy integrodifferential equations with nonlocal initial conditions and forcing term with memory in $E_N$. In this paper, we study the controllability for this system by using the concept of fuzzy number whose values are normal, convex, upper semicontinuous and compactly supported interval in $E_N$.
게이트 산화전 RCA세정 횟수에 따른 Si/SiO₂계의 절연특성에 관한 연구
정양희,유일현,한원열 麗水水産大學校産業技術硏究所 1998 産業基術硏究所 論文集 Vol.7 No.-
The purity of wafer surface is an essential requisite for the successful fabrication of VLSI silicon circuits. The solution used in the cleaning step of silicon wafer surfaces known as "RCA standard clean" has the volume ratios NH₄OH : H₂O₂: H₂O=1:1:5. This RCA cleaning process for bare wafer can affect the state of wafer surfaces. This can cause the degeneration of gate oxide layer. For the investigation of this problem, we measured the Dit(interface trap density) of Si/SiO₂system using the C-V method. The Dit is in the range of 0.89∼2.13×10¹¹[cm-²eV-¹]. This measure is increased proportionally to the number of cleaning times. Leakage current is in the range of 1×10-¹∼1×10(-8)[A] according to the cleaning times, especially, we notice that additional RCA cleaning increases the leakage current in the order of hundred times compared to one times cleaning under 10[V] gate voltage. The electrical breakdown field using the breakdown obtained by I-V method is in the range of 8~12[MV/cm]. This measure is decreased proportionally to the cleaning times. This increment of leakage current by additional RCA cleaning result in the 0.8% decrement of yield. Since cleaning process of before gate oxidation directly affect the device performance and reliability, we think that further investigation is necessary for the clear understanding and of cleaning process.