• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.108-116
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• 1997

A laboratory experiment was made of critical transition flow modes in Czocllralski convection. Numerical computation was also made to delineate the dynamic transition. The period of temperature oscillation ($t_p$) and the interval of temperature oscillation ($\Delta\theta$) were scrutinized to capture the critical transition regime. The mixed convection parameter was varied in the range of $0.134\le Ra/PrRe^2 \le3.804$. The data from calculation were in good agreement with ones from experiment. The influence of the Prandtl number on the transition was examined for Pr ＝ 910, 4445 and 8889. To understand the transition mechanism, the detailed temperature oscillation modes, the isolines of meridional temperature and the axial velocity profiles were investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.895-903
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• 1987

This paper investigates the problem of cracks emanating from a circular hole in an orthotropic infinite plate. The mixed-mode stress intensity factors are obtained by using the modified mapping-collocation method. To investigate the effect of anisotropy and circular hole boundary on crack tip singularity, stress intensity factors are considered as functions of the normalized crack length for various types of laminated composite. The results indicate a strong dependence of the stress intensity factor on the material anisotropy and geometry.

• Conservation Science in Museum
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• v.10
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• pp.21-27
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• 2009

This bamboo brush stand was made by attaching two bamboo tubes together, each 80mm in diameter. On the bottom is a "∞-shaped"wood board made of Ailanthus altissima. The surfaces are decorated with exquisite and dynamic designs of a dragon and clouds, and a deer and pine trees. Part of this bamboo brush stand was damaged, lost, or worn down, prior to conservation treatment. After conservation and recovery treatment, its original form was restored. Earth powder, chalk, and gluten mixture were used as materials to fill in the missing parts. After the original form was restored, thin silk fabric was attached to the inner surface of the glued part to prevent cracking. Traditional materials and repair techniques were used to allow for reversal of treatment, if necessary, as seen in the surface of the restored part being made antiquated with lacquer varnish.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1610-1611
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• 2011

실선로 전력 케이블의 부분방전 측정은 주위 전력설비의 신호들이 혼합되면 정확한 부분방전 진단이 어려운 면이 있다. 본 논문에서는 15kV급 EPR 난연 케이블을 대상으로 거리에 따른 부분방전 신호를 검출 및 감쇄 정도 확인 시험을 통하여 발생 위치 추정 기준을 마련하고자 한다. 이를 위해 길이 500m의 EPR 난연 케이블을 제작하여 모의 선로를 구성하였고, IEC60270에 적합한 Calibrator를 이용하여 신호를 인가한 후 HFCT 센서를 사용하여 일정한 거리를 두고 방전 신호를 검출하고, Techimp사(社)의 PDBASE와 OMICRON사(社)의 MPD600을 이용하여 부분방전 신호를 분류하였다. 전압 인가 지점에서 단계적인 거리증가에 따른 부분방전 신호 감쇄 현상 및 일정 길이(300[m])에 대한 주입 신호별 감도 측정을 분석하였다. 본 논문의 시험대상인 15kV급 EPR 난연 케이블은 원자력 발전소의 배전선으로 사용하기 위해 제작된 것으로, 포설 후 절연체 내에 B/D가 발생했다고 가정했을 때, PD신호의 검출 및 대략적인 위치의 추정은 안전을 최우선시 하는 원자력 발전 및 배전 부문에서 주요한 문제로 부각 될 것이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.59-63
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• 2005

The experimental study has been conducted to investigate the effect of the recirculation zone on the multi-slot film cooling in the ramjet combustor. The recirculation zone which is generated by the protrusion tip on the entrance of the coolant flow path affects on the first slot. Velocity fields, dimensionless temperature fields and adiabatic film cooling effectiveness on the downstream wall of the slot exit are measured. The results show that the film cooling performance is rapidly decreased after the slot exit by the share layer and high turbulence intensity between separated flows and coolant flows.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.246-250
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• 2006

As a result of the rapid development in the digital content industry, designers have to visualize colors across a range of digital media in a relevant and sophisticated manner. The purpose of this study is to develop a new digital color design education curriculum for enhancing learners' capability of digital color management. This study presents an original university-level color design curriculum for digital color learning that includes traditional color learning. In order to develop interactive pedagogy that provides diverse color experiences to students, this study suggestes a blended learning method that combines face-to-face instruction and web-based instruction. Through two case studies at universities, this paper illustrate the effectiveness of the proposed digital color design curriculum.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.2
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• pp.18-26
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• 1998

The major interest of this paper is how the spilled oil over the sea is dispersed into water column especially under the shear and turbulence such as breaking wave. Two hydraulic experiments were conducted to investigate the oil stick break-up characteristics into small and large droplets under the variation of velocity shear and breaking waves. From the experiments in the shear generator and the wave flume, small droplets which have diameters of tens to hundreds of micrometers were uniformly distributed throughout the whole control volume as time goes by. In addition, it can be seen that the weathered spilled oil has a different break-up mechanism from fresh spilled oil.

• Polymer(Korea)
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• v.37 no.3
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• pp.356-361
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• 2013

Microcapsules of two different self-healing agents, 5-ethylidene-2-norbornene (ENB) and ENB with a crosslinker, surrounded by a melamine-urea-formaldehyde shell were manufactured. In this work, a red dye was incorporated into the self-healing agents as a tracer for better visual observations. It revealed that the incorporation of a red dye into self-healing agents did not disturb the formation of microcapsules from the examination of thermal resistance, particle size/size distribution and morphology of the resulting microcapsules. Releasing of self-healing liquid into the induced crack from ruptured microcapsules and filling between crack planes were observed using an optical microscope. Also observed was the reaction of filled healing agent with embedded Grubbs' catalyst in an epoxy coating layer.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.250-254
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• 2000

We have constructed laser Doppler velocimetry system using self-mixing effect with a semiconductor laser. This technology is based on the frequency mixing phenomena which occurs when light scattered back from the moving object into the laser cavity interferes with light inside the laser. We have compared the value of Doppler shifted frequency with the velocity variation of the wheel. Frequency dependence on the angle between the moving direction of rotating aluminum wheel and the incident beam also have been proved. As an illustration of the performance of the velocimeter, velocity measurements of a rotating disk are described. Doppler signal shows a good linear relationship with velocity of rotating disk.

• International Commerce and Information Review
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• v.2 no.2
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• pp.43-68
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• 2000

전자상거래는 비대면(非對面) 거래로 모든 제반과정이 진행되기 때문에 상대에 대한 신뢰성의 문제가 크며, 거래 당사자와 거래 내역에 대한 입증을 해줄 인증기관이 필요하게 된다. 현재 미국의 베리사인 등 사설인증업체가 국내전자상거래 업체의 인증업무를 담당하고 있는 실정이다. 또한, 인증은 필연적으로 관련 기술의 표준화가 수반되는데 이에 대한 국내기술이 미흡하므로 국제동향을 고려한 국내인증기술의 개발이 시급하다. 특히, 글로벌 전자상거래에서는 인증기관에 대한 문제가 더욱 절실한데 문제는 어떠한 형태로 어떤 기관이 주축이 되어 인증체계를 구축하는가 하는 것이다. 현재, 인증체계는 네트워크 방식, 계층구조, 혼합형의 세가지가 논의되고 있으며, 각각의 장단점이 존재하므로 이에 대한 심도있는 논의가 필요하다. 하지만, 이들 가운데 대부분의 국가에서는 계층구조를 바탕으로 한 네트워크 방식이 주류를 이루고 있음에 주목할 필요가 있다. 이러한 체계는 국가별로 상이할 수 있지만, 문제는 글로벌 전자상거래를 활성화하기 위해서는 보다 일관된 형태의 인증체계 구축이 필요하다는 점이다. 현재까지 이와 관련한 논의는 초보적인 단계를 벗어난 실정이며, 미국 EU 등 일부국가와 UNCITRAL, OECD, ICC, WTO 등 관련 기구에서 다양한 의견을 제시하고 있는 상태이다. 이러한 문제는 단시일 내에 해결되기는 어려울 것으로 보인다. 다만, 단기적으로는 관련국가들간의 상호인증을 통한 해결이 선행될 것이며, 이를 바탕으로 글로벌 인증체계가 실현될 것으로 판단된다. 이와 관련하여 인증과 관련한 국내 시장은 출범 초기 단계로서 글로벌 인증 관련 국 내관련 법적 제도적 보완이 필요하며, 이와 아울러 인증서비스를 이용할 사이버무역업계 및 정부 관련 기관 등의 관심이 촉구된다 하겠다.