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저자 : 백동훈 ( Donghun Baek ) , 이주호 ( Jooho Lee )
발행기관 : 충남대학교 기초과학연구원
간행물 :
충남과학연구지
36권 1호
발행 연도 : 2019
페이지 : pp. 1-10 (10 pages)
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Banerjee and Rahim (1988) proposed an economic design of □ control chart for normally distributed data under Weibull shock model. Chen and Yeh (2011) applied Banerjee and Rahim's model on non-normally distributed data using approximation proposed by Burr (1942). Seo (2013) extended Banerjee and Rahim's model using a double sampling scheme proposed by Daudin (1992). In this paper, an economic design of DS □ chart proposed by Seo (2013) is applied on non-normally distributed data using Burr approximation. Numerical examples are provided to show that the optimal designs of the proposed model improve upon those of Chen and Yeh (2011)'s model.
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포아송과정으로 도착하는 고객의 서비스시간이 지수분포를 따르는 대기행렬에서 서버는 시스템에 있는 모든 고객에게 동시에 서비스를 제공한다. 다만 고객은 서버로부터 할당받는 서비스 비율에 비례한 비용을 지불하는데, 그들의 대기 비용과 서비스 비율에 비례한 비용의 합을 최소화하고자 한다. 이러한 시스템에 Nash 평형가격이 존재하는데 어떻게 그리고 언제 평형가격에 도달하는지 고찰한다.
It is considered a single server queue in which customers arrive according to a Poisson process and the service time of each customer follows exponential distribution. The customers purchase relative priority so that they may minimize the sum of their expected waiting cost and the cost they pay for purchasing priority. The server shares its capacity among all customers in system proportionally to the cost they paid. For the system, Nash equilibrium price paid by customers is given and show how and when the paid price reaches the equilibrium price.
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저자 : 양재열 ( Jae Yeol Yang ) , 오병성 ( Byungsung O )
발행기관 : 충남대학교 기초과학연구원
간행물 :
충남과학연구지
36권 1호
발행 연도 : 2019
페이지 : pp. 17-23 (7 pages)
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GaN nanowires have been grown on Ni/GaN epilayer/sapphire substrate by vapor-liquid-solid method with chemical vapor deposition equipment, The substrate temperature was controlled from 600oC to 900oC. The surface morphology was investigated by field-emission scanning electron microscopy. It was found that the nanowires grown around 700oC showed the high quality GaN nanowires with the triangular cross section. X-ray diffraction revealed that the structure of the GaN nanowires have wurzite structure. The temperature-dependent photoluminescence showed the excitonic peaks and the quenching effect was observed.
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The energy distribution function for the study of the dynamics of complex systems was suggested in 1985. This function has been cited even these days and reported to use in the molecular dynamics simulations. The energy distribution function is a product of the normal distribution function and the Boltzmann distribution function. However, the detailed parameters of the function are not reported. In this work, the parameters of the function are examined by simulation of several cases.
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저자 : 최강식 ( Kang Sik Choi ) , 박윤봉 ( Younbong Park )
발행기관 : 충남대학교 기초과학연구원
간행물 :
충남과학연구지
36권 1호
발행 연도 : 2019
페이지 : pp. 29-35 (7 pages)
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In order to improve the thermal quenching effect and emission efficiency in the conventional SrSi2O2N2:Eu2+ phosphor, Sr2+ ions were partially substituted with Mg2+ ions. The resulting (SrMg)Si2O2N2:Eu2+ phosphor was synthesized by a solid-state reaction and was characterized using X-ray powder diffraction and emission spectroscopy. Compared to the pure SrSi2O2N2:Eu2+, the emission intensity of new (SrMg)Si2O2N2:Eu2+ phosphor was increased by 27 %, and the ratio of thermal quenching effect was increased up to 80.5 %. These improvements were mainly due to the size effect of Mg2+, which lead to the relaxation of local strain around the Eu2+ ions in the (SrMg)Si2O2N2:Eu2+ structure. As a result, Sr0.55Mg0.4Si2O2N2:Eu2+0.05 proves a better phosphor with high thermal stability suitable for its white light LED application.
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저자 : 이옥숙 ( Ok Suk Lee ) , 손정훈 ( Jeong-hun Sohn )
발행기관 : 충남대학교 기초과학연구원
간행물 :
충남과학연구지
36권 1호
발행 연도 : 2019
페이지 : pp. 37-41 (5 pages)
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A copper-catalyzed cascade reaction likely proceeded via C-S cross-coupling with concomitant oxidative dehydrogenation under aerobic conditions to convert 3,4-dihydropyrimidine-2(1H)-thiones (DHPMs) to 2-arylthiopyrimidines is described. The reaction method proceeded efficiently with a wide range of the DHPM compounds and aryl iodides as coupling partners.
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