• 한국물환경학회지
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• 제30권2호
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• pp.166-174
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• 2014

Velocity gradient, G, a measure of the average velocity gradient in the fluid has been applied for complete mixing of chemicals in mechanical mixing devices. G values were calculated by the power input transferred to fluid in turbulent and transient range. Chemical reactions occur so fast that total mass transfer time required for even distribution of the chemicals determine the overall reaction time. The total mass transfer time is composed of the time for complete mixing through the reactor and for diffusion of the chemicals into the eddy. Complete mixing time was calculated by CFD (computer fluid dynamics) and evaluated by tracer tests in 2 liter jars at different rotating speeds. Turbulent range, Reynolds number above 10,000 in regular 2 liter jars occurred at revolution speed above 100 rpm (revolution per minute), while laminar range occurred at revolution speed below 10 rpm. A typical range of rotating speed used in jar tests for water and wastewater treatment was between 10 and 300 rpm, which covered both transient and turbulent range. G values supplied from a commercial jar test apparatus showed big difference from those calculated with power number specially in turbulent range. Diffusion time through eddy decreased 1.5 power-law of rotating speed. Complete mixing time determined by pumping number decreased increases in rotating speed. Total mass transfer time, finally, decreases as rotating speed increases, and it becomes 1 sec at rotating speed of 1,000 rpm. Complete mixing times evaluated from tracer tests showed higher than those calculated by power number at higher rotating speed. Complete mixing times, however, calculated by CFD showed similar to those of experimentally evaluated ones.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.118-118
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• 2008

The oxide CMP has been applied to interlayer dielectric(ILD) and shallow trench isolation (STI) in chip fabrication. Recently the slurry used in oxide CMP being changed from silica slurry to ceria (cerium dioxide) slurry particularly in STI CMP, because the material selectivity of ceria slurry is better than material selectivity of silica slurry. Moreover, the ceria slurry has good a planarization efficiency, compared with silica slurry. However ceria abrasives make a material removal rate too high at the region of wafer center. Then we focuses on why profile of material removal rate is convex. The material removal rate sharply increased to 3216 $\AA$/min by $4^{th}$ run without conditioning. After $4^{th}$ run, material removal rate converged. Furthermore, profile became more convex during 12 run. And average material removal rate decreased when conditioning process is added to end of CMP process. This is due to polishing mechanism of ceria. Then the ceria abrasive remains at the pad, in particular remains more at wafer center contacted region of pad. The field emission scanning electron microscopy (FE-SEM) images showed that the pad sample in the wafer center region has a more ceria abrasive than in wafer outer region. The energy dispersive X-ray spectrometer (EDX) verified the result that ceria abrasive is deposited and more at the region of wafer center. Therefore, this result may be expected as ceria abrasives on pad surface causing the convex profile of material removal rate.

• 교육시설 논문지
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• 제28권3호
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• pp.3-14
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• 2021

Speech information of teachers is transmitted to students in classrooms so that appropriate aural environment should be provided for academic purposes. Many researches have been undertaken for classroom acoustics, and acoustic standards of domestic classrooms were suggested based on the reverberation time and background noise level. However, these standards are suitable for middle and high schools and so not consider the auditory ability by ages. As a precedent research, the present study was begun to suggest an acoustic standard for lower grade elementary school classrooms with children under age 9 who have not normal auditory ability. In order to do this, acoustic performances of the lower grade classrooms were measured and compared with the general classrooms. Also, change of acoustic parameters depending on the desk layout was measured and analyzed. The measured acoustic parameters were background noise, signal to noise ratio, RT, STI, D₅₀, and IACC. As a result, it was found that background noise is exceed the standard of 35dB(A) at the schools along the road sides. Also, it was shown that most of acoustic parameters are higher in the classrooms built recently rather than the old classrooms. Generally, there are not much difference of acoustic parameters among the various desk layouts but, better acoustic performances are acquired at the center line and the seats near sound source. Also, Higher IACC was measured at the seats on the center line facing the source squarely.

• Journal of Gastric Cancer
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• 제5권1호
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• pp.40-46
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• 2005

배경: 위장관 간질성 종양(GISTs)은 위장관계에 발생하는 간엽성 종양이다. 위장관 간질성 종양은 면역조직화학 검사에서 c-kit 단백 발현의 양성을 나타내며 그 임상적 경과는 매우 다양하다. 저자들은 위장관 간질성 종양의 임상병리학적 특성을 고찰하고 예후 인자를 평가하기 위하여 후향적 연구를 시행하였다. 대상 및 방법: 본 연구는 고려대학교 의과대학 외과학교실에서 1996년부터 2003년까지 위장관 간질성 종양으로 수술적 절제를 시행한 40명의 환자를 대상으로 하였다. 종양의 크기와 핵분열 정도에 따라 저위험도 집단(23예), 고위험도 집단(17예)으로 분류하였으며 두 군간 임상병리학적 특성, 면역조직화학 검사 결과 및 예후를 비교 분석하였다. 결과: 환자의 평균 연령은 $61.3\pm11.1$세이었으며 남녀비는 1:1,1이었다. 임상병리학적 소견으로는 수술 전 임상 증상이 있었던 경우와 수술 전에 조직학적으로 진단이 되었던 경우, 종양의 크기가 클수록, 핵분열이 많을수록, 종양의 성상이 궤양을 동반하거나 괴사를 보일 때, 고위험군에 포함되는 빈도가 높았다. 단변량 분석 결과, 종양의 크기, 핵분열 정도, 궤양 및 괴사 소견 그리고 내시경적 초음파 이상소견이 통계학적으로 의미가 있는 인자들로 나타났으며, 다변량 분석을 시행한 결과 핵분열 정도가 생존율에 영향을 미치는 독립적인 예후 인자로 나타났다. 관찰 기간 중 8예에서 재발하였으며 STI-571(imatinib mesylate, $Gleeveo^{R}$)을 사용한 4예는 현재까지 생존하고 있으며 사용하지 않은 4예 중 2예는 질환이 진행하는 양상을 나타내었고, 나머지 2P는 사망하였다. 결론: 위에서 기원한 위장관 간질성 종양에서 종양의 크기, 궤양 및 괴사 소견은 생존율에 영향을 주는 임상병리학적 소견이며, 핵분열 정도는 유용한 예후 인자라고 할 수 있다. STI-571은 재발 혹은 전이 환자에 있어 치료 효과를 나타내므로 술후 치료에 적용하는 것이 예후 향상에 기여하리라 생각된다.

• 대한수학회지
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• 제52권3호
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• pp.469-487
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• 2015

We consider a model of HIV infection with various compartments, including target cells, infected cells, viral loads and immune effector cells, to describe HIV type 1 infection. We show that the proposed model has one uninfected steady state and several infected steady states and investigate their local stability by using a Jacobian matrix method. We obtain equations for adjoint variables and characterize an optimal control by applying Pontryagin's Maximum Principle in a linear control problem. In addition, we apply techniques and ideas from linear optimal control theory in conjunction with a direct search approach to derive on-off HIV therapy strategies. The results of numerical simulations indicate that hybrid on-off therapy protocols can move the model system to a "healthy" steady state in which the immune response is dominant in controlling HIV after the discontinuation of the therapy.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.439-440
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• 2002

Nano-Crystalline $CeO_2$ particles were dispersed in deionized water with controlled slurry chemicals for CMP test. According to the CMP test, the removal rate of $SiO_2$ layer was mainly controlled by the size and crystallinity of $CeO_2$ particles which can be controlled by the heat-treatment condition during $CeO_2$ synthesis. In contrast, the removal rate of $Si_3N_4$ layer was significantly influenced by the passivation reagent which protects the $Si_3N_4$ surface layer from excessive dissolution during CMP.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2009년도 추계학술대회
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• pp.243-246
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• 2009

본 연구는 터치 인터페이스를 이용하여 음향 효과 재생 시스템을 개발하였다. 터치 인터페이스를 통하여 손의 위치를 인식하고, 해당 위치에 가상의 공을 생성한다. 움직임을 통하여 시각적 피드백과 음향 효과를 발생시킨다. 사용자는 오브젝트의 크기와 위치를 조정하여 창조적인 음향 효과를 얻을 수 있다. 따라서 본 시스템은 터치 인터페이스를 이용하여 사용자와 시 청각적 상호작용을 할 수 있는 인터페이스를 제안한다.

• STI Policy Review
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• 제2권2호
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• pp.45-54
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• 2011

This paper develops a recursive multinomial probit model and describes its estimation method. The recursive multinomial probit model is an extension of a recursive bivariate probit model. The main difference between the two models is that a single decision among two or more alternatives can be considered in each choice equation in the proposed model. The recursive multinomial probit model is developed based on a standard framework of the multinomial probit model and a Bayesian approach with a Gibbs sampling is adopted for the estimation. The simulation exercise with artificial data sets is showed that the model performed well. Since the recursive multinomial probit model can be applied to analyze the causal relationship between discrete dependent variables with more than two outcomes, the model can play an important role in extending the methodology of the causal relationship analysis in innovation research.

• World Technopolis Review
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• 제5권1호
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• pp.61-70
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• 2016

Entrepreneurship development has increasingly become a global solution to address the problem of rising unemployment. Science, Technology and Innovation (STI) have become important tools in improving the economic performance and social well-being of nations. When universities and industry work together to push the boundaries of knowledge, they become a powerful engine for innovation and economic growth. This paper is based on focus group interviews and discussions conducted with key players involved in the HIT-Sandown-UNDP Business Incubation Programme in Harare Zimbabwe. The business incubation project sought to support young Zimbabweans to transform their technical prototypes into commercially and socially viable ventures. As a result, a total of 10 prototypes were refined and investor ready business plans were developed for capital sourcing purposes. It was only through the coming together of the partners that real transformation of the lives of the participants was achieved through learning valuable business skills, coaching and mentoring. University-industry partnerships are a useful vehicle of setting up sustainable business incubation centres.

• World Technopolis Review
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• 제6권2호
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• pp.113-129
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• 2017

Universities are considered important actors and drivers of socio-economic development in the regional innovation eco-system. This article investigates the role Kenyan universities and research institutes play in the development of regional innovation eco-system in the context of triple and Quadruple helices. A model involving Government, Industry, Universities and Society (Public) linkages in the regional innovation eco-system and with Information and Communication Technology as an enabler is used as a framework for analysing the nature of linkages in Kenya. The article uses literature review and case study methods to examine how universities and research institutes can spur the development of the innovation eco-systems. The research question is: what is the role of Kenyan universities and research institutes in spurring innovation ecosystems? Six cases of Kenyan universities and research institutes are considered in the light of Government Policy on Science, Technology and Innovation (STI) which is underpinned in Kenyan constitution 2010. The study contributes to the understanding of how deep collaboration among universities, government, research institutes, Science Cities, local, regional, national and international players spurs the creation of world-class innovation ecosystems which can contribute to regional development in developing countries like Kenya.