• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.3017-3029
• /
• 2023

In the late in-vessel phase of a nuclear reactor severe accident, the internal heat transfer and crust evolution during the debris bed melting process have important effects on the thermal load distribution along the vessel wall, and further affect the reactor pressure vessel (RPV) failure mode and the state of melt during leakage. This study coupled the phase change model and large eddy simulation to investigate the variations of the temperature, melt liquid fraction, crust and heat flux distributions during the debris bed melting process in the hypothetical severe accident of HPR1000. The results indicated that the heat flow towards the vessel wall and upper surface were similar at the beginning stage of debris melting, but the upward heat flow increased significantly as the development of the molten pool. The maximum heat flux towards the vessel wall reached 0.4 MW/m². The thickness of lower crust decreased as the debris melting. It was much thicker at the bottom region with the azimuthal angle below 20° and decreased rapidly at the azimuthal angle around 20-50°. The maximum and minimum thicknesses were 2 and 90 mm, respectively. By contrast, the distribution of upper crust was uniform and reached stable state much earlier than the lower crust, with the thickness of about 10 mm. Moreover, the sensitivity analysis of initial condition indicated that as the decrease of time interval from reactor scram to debris bed dried-out, the maximum debris temperature and melt fraction became larger, the lower crust thickness became thinner, but the upper crust had no significant change. The sensitivity analysis of in-vessel retention (IVR) strategies indicated that the passive and active external reactor vessel cooling (ERVC) had little effect on the internal heat transfer and crust evolution. In the case not considering the internal reactor vessel cooling (IRVC), the upper crust was not obvious.

• Animal Systematics, Evolution and Diversity
• /
• 제21권1호
• /
• pp.21-30
• /
• 2005

인천연안에서 채집한 부유성 빈모류인 Pelagostrobilidium simile의 형태 형성과정을 pyridine silver carbonate impregnation 염색법을 이용하여 관찰하였다. p. simile의 형태형성은 전형적인 hypoapokinetal mode로 입섬모열은 모세포의 체섬모와 관계없이 독립적으로 세포막 안에서 외부로 노출되는 입원기로부터 형성되었다. 입원기는 anarchic field의 증식으로 외부 입섬모열 아래에서 시작되었다. 딸세포 prefer와 opisthe의 체섬모상은 분열하는 동안 기저체의 증식으로 모세포 체섬모 구조로부터 나왔다. 모세포의 입 기구는 딸세포 prefer로 전달되고 모세포의 입섬모구조에서 입기구의 새로운 형성은 관찰되지 않았다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.423-425
• /
• 2001

The Proper Orthogonal Decomposition (POD) technique was applied to investigate the effects of Reynolds number and the characteristics of the organized motions or coherent structures as a function of downstream position from x/D=2 to 6 in a turbulent axisymmetric shear layer at Reynolds numbers of 78,400, 117,600, and 156,800. Data were collected simultaneously using the 138 hot-wire probe used by Citriniti and George (2000). The POD was then applied to a double Fourier transform in time and azimuthal direction of the double velocity correlation tensor. The lowest azimuthal mode for all POD modes, which dominated the dynamics at x=D = 3 in the previous experiments, dies off rapidly downstream. This is consistent with a trend toward homogeneity in the downstream evolution, and suggests that some residual value may control the growth rate of the far jet. On the other hand, for the higher azimuthal modes, the peak shifts to lower mode numbers and actually increases with downstream distance. These mixing layer data, normalized by similarity variables for the mixing layer, collapse at all downstream positions and are nearly independent of Reynolds numbers.

• 패션비즈니스
• /
• 제3권4호
• /
• pp.103-112
• /
• 1999

The purpose of this study is to investigate the various expressions in fashion design using logo. For this study, fashion magazines such as Vogue, Elle, WWD, Hi Fashion, Mode et Mode, Fashion News, Collezioni were analyzed. A corporate identity consists of the logo and name owned by a company together with the rules and guidance on how these are to be used, for example in printed material such as letterheads, catalogues and reports, in advertising, marketing and promotion, and on produsts and services. Logos provide the bedrock for the development of corporate identities, for the evolution of commercial brands, and for the nurturing of corporate culture. Logo is a primary means of communicating corporate values to customers and designers. It represents an asset of incalculable value, because it has been consistently maintained and protected over the years. The logo is the cornerstone of the company‘s image and the style of a logo or products name must harmonize with the feeling of the product or brand image. Fashion designers today are using their logos in different forms of communication. It is common to see a brand’s logo proudly emblazoned the classic chic garments as well as accessories such as bags, shoes, caps. The consumer, then becomes a ‘walking ad’ for the brand.

• 전산구조공학
• /
• 제10권4호
• /
• pp.229-238
• /
• 1997

본 논문에서는 반복하중에 의해 손상을 입은 아스팔트 콘크리트의 점탄성 구성모델에 대한 역학적 접근방법을 제시하였다. 모의변수로 나타낸 탄성-점탄성 일치원리는 아스팔트 콘크리트의 점탄성과 시간의존 손상의 증가를 별도로 평가하도록 적용되었다. 선형-점탄성 파괴역학에 사용되고 있는 미소균열의 증가법칙이 물체내 손상증가를 나타내는데 성공적으로 사용되었다. 응력과 모의변형도로 나타나는 구성방정식은 먼저 변형도조절에 대해 세워졌으며, 응력과 모의변형도를 모의응력과 변형도로 간단하게 대체함으로써 응력조절 구성방정식으로 변형되었다. 모의응력으로 나타낸 변형된 구성방정식은 응력조절모드에서 파괴에 이르는 아스팔트 콘크리트의 모든 역학적 거동을 충분히 예측하고 있다.

• Structural Engineering and Mechanics
• /
• 제57권2호
• /
• pp.295-313
• /
• 2016

In this study, the three-dimensional finite element method is used to determine the stress intensity factor in Mode I and Mixed mode of a centered crack in an aluminum specimen repaired by a composite patch using contour integral. Various mesh densities were used to achieve convergence of the results. The effect of adhesive joint thickness, patch thickness, patch-specimen interface and layer sequence on the SIF was highlighted. The results obtained show that the patch-specimen contact surface is the best indicator of the deceleration of crack propagation, and hence of SIF reduction. Thus, the reduction in rigidity of the patch especially at adhesive layer-patch interface, allows the lowering of shear and normal stresses in the adhesive joint. The choice of the orientation of the adhesive layer-patch contact is important in the evolution of the shear and peel stresses. The patch will be more beneficial and effective while using the cross-layer on the contact surface.

• Journal of the Optical Society of Korea
• /
• 제7권4호
• /
• pp.253-257
• /
• 2003

We propose and demonstrate a novel polarization- and wavelength-independent digital electrooptic switch in $Ti:LiNbO_3$ with switching voltage of ${\pm}$32V at $1.55{\mu}m$ wavelength. This $2{\times}2$ integrated optic switch is characterized by a step-like response to the applied voltage. Switching is achieved through adiabatic mode evolution in an asymmetric waveguide junction. An average insertion loss of ∼4.5dB and polarization independent switching with average crosstalk of -12dB are achieved.

• STI Policy Review
• /
• 제1권4호
• /
• pp.29-39
• /
• 2010

Science, technology, society and humanities (STSH) fusion research is aimed at creating new research areas and methods that can resolve complicated issues in society that cannot be solved by a single academic discipline. This study identifies initiatives that can promote STSH fusion research in Korea. We review the definition and characteristics of STSH fusion research to analyze the necessity of STSH fusion research with a focus on the structural changes in the S&T environment. The emergence and diffusion of generic technologies, transition to post catch-up innovation mode, and the evolution of policy to the third generation innovation policy are identified as notable changes. This paper briefly reviews the status of fusion research underway and presents initiatives to promote STSH fusion research.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.39-42
• /
• 1998

In this paper is design of signal discriminatior system for the third generation mobile telecommunication system (IMT-2000 : International mobile telecommunication service-2000) This system is basically using multiplexing method of CDMA, TDMA and FDMA that this system can be solved third generation systems problems-Frequency bandwidth, international roaming and development new architecture of mobile telecommunication systems. Designed signal discriminator system is perfectly separated three styles multiplexing method signals that more easily, nearly and economically implementation of third generation telecommunication systems. As we develop signal discriminator we will contribute to technical evolution of mobile telecommunication for third generation and stay ahead in the interior technical accumulation in addition to international intercourse as to mobile telecommunication.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
• /
• pp.207-210
• /
• 2002

Metal matrix composites(MMCs) are increasingly attractive for high technology components such as aerospace applications and transportations due to their high strength, stiffness, and toughness. Many processes for fabricating MMCs have been developed, and relatively simple Foil-Fiber-Foil method is usually employed in solid state consolidation processes. During the consolidation processes at high temperature, densification occurs by the inelastic flow of the matrix materials, and the process is coupled with the conditions of pressure, temperature and volume fraction of fiber and matrix materials. This is particularly important in titanium matrix composites, and thus a generic model based on micro-mechanical approaches enabling the evolution of density over time to be predicted has been developed. The mode developed is then implemented into FEM so that practical process simulation has been carried out. Further the experimental investigation of the consolidation behavior of SiC/Ti-6Al-4V composites using vacuum hot pressing has been performed, and the results obtained are compared with the model predictions.