• Corrosion Science and Technology
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• 제23권2호
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• pp.93-103
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• 2024

In the present work, a phase-field model for dendritic solidification is applied to hot-dip ZnAlMg coatings to elucidate the morphology of zinc dendrites and the solute segregation leading to the formation of eutectics. These aspects define the microstructure that conditions the corrosion resistance and the mechanical behaviour of the coating. Along with modelling phase transformation and solute diffusion, the implemented model is partially coupled with the tracking of crystal orientation in solid grains, thus allowing the effects of surface tension anisotropy to be considered in multi-dendrite simulations. For this purpose, the composition of a hot-dip ZnAlMg coating is assimilated to a dilute pseudo-binary system. 1D and 2D simulations of isothermal solidification are performed in a finite element solver by introducing nuclei as initial conditions. The results are qualitatively consistent with existing analytical solutions for growth velocity and concentration profiles, but the spatial domain of the simulations is limited by the required mesh refinement.

• KDI Journal of Economic Policy
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• 제35권3호
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• pp.65-89
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• 2013

본 연구는 파리선언(2005)의 개발효과를 평가하는 것을 목적으로 한다. 구체적으로 말하면, OECD/DAC가 78개의 개도국으로부터 수집한 2005~10년 기간의 자료를 이용하여, 파리선언의 여러 원칙이 독자적으로 또는 원조와의 상호작용을 통하여 1인당 국민소득의 성장에 기여한 정도를 평가한다. 본 연구의 결과에 의하면, 원조가 독자적으로 국민소득의 증가에 기여한 효과는 부정적이다. 그러나 건전한 정책과 제도가 있는 개도국 또는 파리선언의 몇 가지 원칙이 실시된 국가에서는 원조의 효과가 긍정적이었다. 파리선언의 다섯 가지 원칙 중에서 오직 원조가 개도국의 개발전략과 계획에 연계되어야 한다는 원칙이 적용된 경우와 원조공여국-수원국 상호 간에 상호책임의 원칙이 적용된 경우에는 원조가 경제성장에 긍정적이며 유효한 영향을 미쳤다는 것을 보여 준다. 따라서 파리선언의 원칙들이 원조의 효과성을 제고한다는 OECD의 주장은 오직 부분적으로만 실증된 셈이다. 원조와 파리선언의 개발효과에 관한 이러한 실증적 분석 결과는 건전한 제도나 정책이 경제성장에 중요하다는 경제학 문헌의 주장과 앞으로의 국제개발협력의 논의과제에 주는 의미가 크다.

• 대한기계학회논문집A
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• 제36권4호
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• pp.379-386
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• 2012

본 논문의 주 목적은 확률변수의 잔차를 이용하여 제안된 확률론적 피로균열전파모델들을 평가하고 Mg-Al-Zn 합금의 확률론적 피로거동을 묘사하기에 적합한 모델을 제시하는 것이다. 제안된 모델은 '확률론적 Paris-Erdogan 모델', '확률론적 Walker 모델', '확률론적 Forman 모델'과 '확률론적 수정 Forman 모델'이다. 이 모델들은 실험적 피로균열전파모델인 Paris-Erdogan 모델, Walker 모델, Forman 모델과 수정 Forman 모델에 확률변수를 도입하여 준비하였다. Mg-Al-Zn 합금의 피로균열전파거동을 묘사하기에 적합한 모델은 일반적으로 '확률론적 Paris-Erdogan 모델'과 '확률론적 Walker 모델'임을 밝혔으며, 시편두께 9.45mm 에서는 '확률론적 Forman 모델'이 적합하였다.

• Advances in biomechanics and applications
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• 제1권4호
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• pp.227-237
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• 2014

The in vitro construction of osteo-articular large implants combining biomaterials and cells is of great interest since these tissues have limited regeneration capability. But the development of such organoids is particularly challenging, especially in the later time of the culture, when the extracellular matrix has almost filled the initial porous network. The fluid flow needed to efficiently perfuse the sample can then not be achieved using only the hydraulic driving force. In this paper, we investigate the interest of using an electric field to promote mass transport through the scaffold at the late stage of the culture. Based on the resolution of the electrokinetics equations, this study provides an estimation of the necessary electric driving force to reach a sufficient oxygen perfusion through the sample, thus analyzing the feasibility of this concept. The possible consequences of such electric fields on cellular activities are then discussed.

• 생약학회지
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• 제39권2호
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• pp.91-94
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• 2008

Column chromatographic separation of the MeOH extract from the aerial parts of Paris verticillata led to the isolation of three phenolics, two terpene glucosides and two pyrrolidine alkaloids. Their structures were characterized to be methyl caffeate (1), 5-hydroxy pyrrolidin-2-one (2), vanillic acid (3), benzyl alcohol glucopyranoside (4), (6S, 9R)-roseoside (5), staphylionoside H (6) and 5-methoxy pyrrolidin-2-one (7) by spectroscopic means. The isolated compounds (1-7) were for the first time reported from this source. The isolated compounds were tested for their cytotoxicity against four human tumor cell lines by SRB method in vitro.

• STI Policy Review
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• 제1권1호
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• pp.43-62
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• 2010

Whatever the country, nanotechnology features as a key priority of most national research and innovation policies. This focus on nanotechnology is due to the promises of this general purpose technology, this new technological wave. As 'one size does not fit all', policies supporting its development cannot just adopt the 'best practices' of the preceding wave. We argue that specific on-going dynamics of nanoscience and technology production justifies the existence of dedicated nanotechnology policies. It also questions the portfolio of instruments mobilized and their balance. In this article, we discuss policies developed for the preceding technological waves and, based on the characteristics of nanosciences and technologies, propose five dimensions of policies to be taken into consideration for their governance at the country and cluster levels.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제18권1호
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• pp.26-32
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• 1996

This study was performed to determine the ideal mixing ratio of toothash and plaster of Paris. The histopathologic and histomorphometric study of bone response of five implant materials, toothash(Group A), tooth and plaster mixture, mixing ratio due to weight 2 : 1(Group B), 3 : 1(Group C), 4 : 1(Group D), and plaster Paris(Group E), were performed in rat calvarial defect. No sign of extensive inflammatory reaction was defected. Newly-formed bony ingrowth occurred in all experimental groups except for group E at 12 weeks after operation. Bone was deposited directly on the surface of implant materials. The highest rate of direct bony union between implant material and newly-formed bone occurred with the group B, followed group C, D, and A.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 봄 학술발표논문집 Vol.30 No.1 (A)
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• pp.43-45
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• 2003

초고속 네트워크에 연동된 고성능 컴퓨팅 자원들을 효율적으로 활용하려는 그리드 컴퓨팅(Grid computing) 기술은 네트워크를 통한 기존의 단순한 정보 공유(Information sharing)뿐만 아니라 자원의 공유 (Resource sharing)를 통해 분산된 자원들의 통합을 가능하게 한다. 이상적인 그리드 컴퓨팅 환경을 구축하기 위해서는 무엇보다도 그리드 환경에 속한 자원들의 정보를 통합적으로 관리 및 서비스하는 것이 무엇보다도 중요하다. 그리드 정보서비스의 역할은 그리드 사용자가 필요한 자원 및 그에 대한 정보를 쉴게 찾을 수 있도록 다양한 검색 기능을 제공하는 것 이외에도, 전세계에 분산된 자원들의 최신 정보를 빠르게 서비스하도록 하여야 한다. 이를 위해서는 그리드 환경의 특성을 고려하여 효율적인 그리드 정보 서비스 아키텍쳐를 구성하는 것이 필요하다. 본 논문에서는 기존에 널리 사용되는 그리드 정보 서비스(MDS) 모듈 구조인 클라이언트/서버 구조가 아닌 피어-투-피어 구조의 정보 서비스 구조(PARIS)를 제안한다. 이는 그리드 자원 활용의 지역성과 사용자 접근 패턴에 따라 정보 서비스의 정확성을 높이면서 지연 시간을 획기적으로 감소시킬 수 있다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.138-139
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• 2006

Sintered steels are materials characterized by residual porosity, whose dimension and morphology strongly affect the fatigue crack growth behaviour of the material. Prismatic specimens were pressed at $7.0\;g/cm^3$ from Astaloy CrM powder and sintered varying the sintering temperature and the cooling rate. Optical observations allowed to evaluate the dimensions and the morphology of the porosity and the microstructural characteristics. Fatigue tests were performed to investigate the threshold zone and to calculate the Paris law. Moreover $K_{Ic}$ tests were performed to complete the investigation. Both on fatigue and $K_{Ic}$ samples a fractographic analysis was carried out to investigate the crack path and the fracture surface features. The results show that the Paris law crack growth exponent is around 6.0 for $1120^{\circ}C$ sintered and around 4.7 for $1250^{\circ}C$ sintered materials. The same dependence to process parameters is not found for $K_{Ith}$.

• 한국자동차공학회논문집
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• 제13권4호
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• pp.19-25
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• 2005

This paper presents a lateral control system for the autonomous navigation vehicle that was developed and tested by Robotics Centre of Ecole des Mines do Paris in France. A robust lane detection algorithm was developed for detecting different types of lane marker in the images taken by a CCD camera mounted on the vehicle. $^{RT}Maps$ that is a software framework far developing vision and data fusion applications, especially in a car was used for implementing lane detection and lateral control. The lateral control has been tested on the urban road in Paris and the demonstration has been shown to the public during IEEE Intelligent Vehicle Symposium 2002. Over 100 people experienced the automatic lateral control. The demo vehicle could run at a speed of 130km1h in the straight road and 50km/h in high curvature road stably.