• 대한금속재료학회지
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• 제46권2호
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• pp.58-64
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• 2008

Surface-void defects observed on the galvannealed(GA) steel sheets in Interstitial-free high-strengthened steels containing Si and Mn have been investigated using the combination of the FIB(Focused Ion Beam) and FE-TEM(Field Emission-Transmission Electron Microscope) techniques. The scanning ion micrographs of cross-section microstructure of defects showed that these defects were identified as craters which were formed on the projecting part of the substrate surface. Also, those craters were formed on the Si or Mn-Si oxides film through the whole interface between galvannealed coating and steel substrate. Interface enrichments and oxidations of the active alloying elements such as Si and Mn during reduction annealing process for galvanizing were found to interrupt Zn and Fe interdiffusion during galvannealing process. During galvannealing, Zn and Fe interdiffusion is preferentially started on the clean substrate surface which have no oxide layer on. And then, during galvannealing, crater is developed with consumption of molten zinc on the oxide layer.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3888-3896
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• 2022

Nuclear data is the basis of reactor physics analysis. This paper aim at studying the influence of major evaluated nuclear data libraries, CENDL-3.2, ENDF/B-VIII.0, JEFF-3.3, and JENDL-4.0u, on the neutronics modelling of CEFR start-up tests. Results show these four libraries have a good performance and consistency in the modelling CEFR start-up tests. The JEFF-3.3 results exhibit only an 8 pcm k_eff difference with the measurement. The difference in criticality is decomposed by nuclide, which shows the large overestimation of CENDL-3.2 is mainly from the cross-section of ⁵²Cr. Except for few cases, the calculation results are within 1σ of measurement uncertainty in control rod worth, sodium void reactivity, temperature reactivity, and subassembly swap reactivity. In the evaluation of axial and radial reaction distribution, there are about 65% of relative errors that are less than 5% and 82% of relative errors that are less than 10%.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3897-3908
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• 2022

High-fidelity nuclear data libraries and neutronics simulation tools are essential for the development of fast reactors. The IAEA coordinated research project on "Neutronics Benchmark of CEFR Start-Up Tests" offers valuable data for the qualification of nuclear data libraries and neutronics codes. This paper focuses on the verification and validation of the CEFR start-up modelling using OpenMC Monte-Carlo code against the experimental measurements. The OpenMC simulation results agree well with the measurements in criticality, control rod worth, sodium void reactivity, temperature reactivity, subassembly swap reactivity, and reaction distribution. In feedback coefficient evaluations, an additional state method shows high consistency with lower uncertainty. Among 122 relative errors in the benchmark of the distribution of nuclear reaction, 104 errors are less than 10% and 84 errors are less than 5%. The results demonstrate the high reliability of OpenMC for its application in fast reactor simulations. In the companion paper, the influence of cross-section libraries is investigated using neutronics modelling in this paper.

• Steel and Composite Structures
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• 제44권2호
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• pp.183-198
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• 2022

Plastic deformation of link beams in eccentrically braced frames is the primary dissipating source of seismic energy. Despite the excellent compatibility with the architectural designs, previous researches indicate the deficiency of flexural yielding links compared to the shear yielding ones because of their localized plastic deformation. Previous investigations have shown that implementing web openings in beams could be an efficient method to improve the seismic performance of moment-resisting connections. Accordingly, this research investigates the use of flexural links with stiffened and un-stiffened web openings to eliminate localized plasticity at the ends of the link. For this purpose, the numerical models are generated in finite element software "Abaqus" and verified against experimental data gathered from other studies. Models are subjected to cyclic displacement history to evaluate their behavior. Failure of the numerical models under cyclic loading is simulated using a micromechanical based damage model known as Cyclic Void Growth Model (CVGM). The elastic stiffness and the strength-based and CVGM-based inelastic rotation capacity of the links are compared to evaluate the studied models' seismic response. The results of this investigation indicate that some of the flexural links with edge stiffened web openings show increased inelastic rotation capacity compared to an un-perforated link.

• 전기화학회지
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• 제5권3호
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• pp.153-158
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• 2002

전해전착법을 이용한 상감(damascene)구리 배선 충전시 레벨러 효과에 대해 연구하였다. 레벨러를 첨가한 도금액과 첨가하지 않은 도금액을 제조하여 선 폭이 $0.37{\mu}m,\;0.18{\mu}m$인 선형 트렌치를 충전한 후 field emission scanning electron microscope(FE-SEM)로 트렌치 단면을 관찰하였다. 레벨러로 Janus Green B를 사용하였으며, 억제제로서 polyethylene glycol(PEG), 촉진제로서 3-mercapto-1-propansulfonic acid를 사용하였다 레벨러를 첨가하지 않은 경우 $0.37{\mu}m$(종횡비 2.7:1) 트렌치를 공극 없이 충전할 수 있었으나 $0.18{\mu}m$(종횡비 5.25:1) 트렌치에서는 공극(void)이 형성되었다. 레벨러를 첨가한 경우에는 $0.18{\mu}m$ 트렌치를 공극 없이 충전할 수 있었다. 레벨러를 첨가하지 않은 경우 트렌치 모서리에서의 전착속도를 충분하게 억제하지 못하고 거칠게 전착되어 미세한 트렌치 충전시 공극을 형성한 반면, 레벨러를 첨가한 경우는 트렌치 상부모서리에서의 전착속도를 억제하고 균일한 전착을 유도하여 미세한 트렌치를 공극 없이 채울 수 있었다.

• 한국지반환경공학회 논문집
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• 제13권5호
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• pp.13-24
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• 2012

국토의 효율적 이용과 기간시설 수용을 위한 대단위 부지 확충 및 대규모 항만배후부지 개발이 계획 중에 있으며, 이에 따라 해안지역의 준설매립은 지속적으로 이루어지고 있다. 슬러리 상태의 초연약 상태인 준설매립 지반은 오랜 시간에 걸쳐 침강 및 자중압밀 과정을 거치게 되며 투기한 준설토를 압밀 촉진시켜 침하시킬 수 있다면 기존 처분지의 수명을 연장시킬 수 있으므로 경제적으로 유용하리라 판단된다. 재하중 없이 공기를 단축시키고 매립 물량을 증대시키기 위하여 small column test와 medium column을 보완, 개발한 medium column test를 실시하여 PBD와 침투압이 동시에 작용하였을 PBD의 효과 및 침투압의 침강 및 자중압밀 촉진 효과를 검토하였다. 연구 결과, 기존의 자중압밀 공법에 비하여 침투압과 PBD를 적용한 지반은 배수재의 배수거리 단축에 따른 투수 상승 효과와 침투압에 의한 침투 압밀의 효과가 활발히 이루어지는 것으로 나타났다. 이를 통해 매립 직후나 매립 도중에 연직드레인을 직접 타설하여 침강 및 자중압밀 과정을 단축시키면 전체 매립공사 공기를 단축시킬 수 있으며 압밀촉진에 따라 확보된 여유고 만큼 준설토 투기가 가능해져 투기 준설토량을 경제적으로 증대시킬 수 있을 것으로 기대된다.

• Journal of Advanced Marine Engineering and Technology
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• 제18권5호
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• pp.12-23
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• 1994

The two-phase flow is observed in power plants, chemical process plants, and refrigeration systems etc., and it is very important to solve the heat transfer mechanism of a boiler, an automic reactor, a condenser and various types of evaporators. Recently, the problem of two phase heat transfer is braught up in many regions with development of energy saving technique. In flow boiling system it is necessary to store data in each condition because the heat transfer characteristics of flow boiling region vary by the change of flow pattern and the magnetude of heat flux to tube length, and be subtly affected by the flow and heating condition. So basic study for knowing flow pattern in heat transfer region and the relation between heat transfer characteristic and flow condition is desired to accumulate data in wide variety of liquid and flow system in the study of heat transfer of two phase flow. In this study R-113 was selected as working fluid whose properties were programmed by least square method, and experiment was conducted in the region of mass flow $1.628{\times}10^6$~$4.884{\times}10^6$/kg/$m^2$hr with inlet subcooling 10~3$0^{\circ}C$, sustaining test section inlet pressure to 1.5kg$_f$/$cm^2$abs.

• 한국지진공학회논문집
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• 제13권2호
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• pp.1-14
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• 2009

교각의 합리적이고 경제적인 내진설계를 위해서는 연성도에 기반한 내진설계가 필요하며 이를 위해서는 신뢰성 있는 전단평가가 필수적이다. RC 기둥의 전단거동은 휨거동과 달리 부재의 단면크기, 형상비, 축력, 연성도 등 다양한 요인에 의하여 영향을 받아 거동이 매우 복잡하다.따라서,이들 요인을 고려한 많은 설계식 및 경험식이 제안되고 있으나 부재의 초기전단강도와 연성도에 따른 전단강도 저하를 평가하는데 상당한 차이를 보이고 있다. 본 연구에서는 형상비,단면의 중공비, 복부면적, 하중패턴을 변수로 하는 실험적 연구를 수행하여 중공단면 기둥의 초기 전단강도 특성을 살펴보았다. 실험결과는 기존의 다양한 전단평가식과 비교.검토하여 특성을 분석하였으며, 역학적 특성과 실험결과에 기초하여 보다 합리적인 초기 전단평가식을 제안하고 타당성을 검토하였다.

• 한국실내디자인학회논문집
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• 제12호
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• pp.10-17
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• 1997

The lastest art is being characterised by an ever active exchange between different genre. This is a study on the installation aspect in deconstruction architectured and interior design. The progressive and aggressive nature of installatation art embodies uncatagorized genre, the freedom of material application, introduction of the notion of time in space, the reversion of subject and object, the union of art and every experience, understanding of object through deconstruction, enlargement of concept of space, collage-style composition and layer technique. I can conclude that the installation aspect in Tshumi's Parc de la Villette is its call upon the audience to actively participate, the introduction of a coincidental conjunction, its challenge on the conventional idea of park and its flexibility caused by human activity and time. In Hadid's Hong Kong Peak Club the installation aspect is the application of layer technique using four enormous beams horizontally laid out on a man-made moutain. Furthermore, Libeskind's pursuit of the mental in Berlin Museum Extension through the penetration of an invisible line into a void creates a new interpretation of the role of a museum and thus relates itself to installation art. The installation aspect in Himmelblau's Vienna Roof Renovation is the literal deconstruction of the roof of an old building in the old section of Wien and the expression of time and space through the interrelationship between interior and exterior environment by the use of juxtaposition technique. Finally, I note that the installation aspect in Gehry's Santa Monica Residence is the reorganization of cheap material as a form of 'object', that creates spon-taneity, movement as well as flow of time in space and ex-hibit the double-sidedness of the visible world.

• 한국지진공학회논문집
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• 제14권2호
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• pp.27-36
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• 2010

횡하중을 받는 RC 기둥의 전단강도는 기둥의 변위연성도가 증가함에 따라 감소하는 것으로 알려져 있다. 연성도의 증가에 따른 전단강도의 감소율은 초기전단강도에 따라 크게 좌우되므로 이를 합리적으로 예측하기 위해서는 초기전단강도의 평가가 매우 중요하다. 기둥의 전단거동은 단면모양, 형상비, 축력, 축방향철근비, 연성도 등 다양한 요인에 의하여 영향을 받아 복잡하다. 본 연구에서는 형상비, 단면의 중공비, 축방향철근비, 중공 및 중실단면을 변수로 하는 시험체를 제작하여 실험적 연구를 수행하여 전단거동특성을 살펴보았다. 또한, 축방향철근이 전단강도에 미치는 영향을 분석하여 형상비와 축력을 고려한 기존의 초기전단평가식을 보완하였으며, 그 타당성을 검증하였다.