• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.450-457
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• 2018

To design the practical core-shell electrocatalysts, combination of core and shell materials is important to meet catalytic activity and durability target. In general, Pd is considered as a good core material due to its best activity caused by strain/ligand effect. Preparing Pd nanoparticles can be a starting point in fabricating core-shell type electrocatalysts, much simplified Pd preparing process is suggested by using carbon monoxide (CO) as a reducing agent and/or capping agent. The solvent composition and reaction temperature can control to nanosheet, tetrahedron, and sphere without using additional stabilizer. Among them, Pd nanosheet which has mainly (111) plane showed about 3 times higher electrocatalytic activity for oxygen reduction reaction (ORR) to the spherical Pd nanoparticles. The enhanced ORR activity of Pd nanosheets can be attributed to the exposure of Pd (111) surface and the high electrochemical surface area. Therefore, we demonstrated that the shape of Pd nanomaterials is easily controlled via a facile reduction method using CO, and (111) plane-oriented Pd nanosheets can be a promising ORR catalysts and core material for polymer electrolyte fuel cells (PEFCs).

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.682-682
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• 2005

• 펄프종이기술
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• 제31권2호
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• pp.70-76
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• 1999

This study was to measure the potential of nonwoody fibrous material, kenaf. Whole stalk of kenaf, Hibiscus cannabinus was separated by two parts of bast and core portion, and cooked separately by alkaline method. Morphological characteristic was evaluated using confocal laser scanning microscope (CLSM) and fiber quality analyzer(FQA). The strength properties of handsheets, made by different mixing ration between kenaf base and core fibers, were measured. Cross-sectional area of bast fibers was smaller than that of core fibers, but the bast fibers had a thick cell wall and narrow lumen area. Bast fibers were longer in length than core fibers. Core fibers had thin cell walls, broad lumen areas, and short lengths, and they had collapsed shape even in water. These characteristics of core fibers affected strength properties of handsheet positively. When the amount of core fibers increased, the strength properties of handsheet were increased. When the amount of bast fibers increased, the handsheet had rougher surface and higher air permeability.

• 한국전산유체공학회지
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• 제14권2호
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• pp.59-67
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• 2009

An accurate prediction of the bypass flow is of great importance in the VHTR core design concerning the fuel thermal margin. Nevertheless, there has not been much effort in evaluating the amount and the distribution of the core bypass flow. In order to evaluate the behavior and the distribution of the coolant flow, a unit-cell experiment was carried out. Unit-cell is the regular triangular section which is formed by connecting the centers of three hexagonal blocks. Various conditions such as the inlet mass flow rate, block combinations and the size of bypass gap were examined in the experiment. CFD analysis was carried out to analyze detailed characteristics of the flow distribution. Commercial CFD code FLUENT 6.3 was validated by comparing with the experimental results. In addition, SST model and standard k-$\varepsilon$ model were validated. The results of CFD simulation show good agreements with the experimental results. SST model shows better agreement than standard k-$\varepsilon$ model. Results showed that block combinations and the size of the bypass gap have an influence on the bypass flow ratio but the inlet mass flow rate does not.

• BMB Reports
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• 제41권10호
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• pp.733-738
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• 2008

Although previous studies have implicated a role for TC1 (C8orf4) in cancer cell proliferation, the molecular mechanism of its action is still largely unclear. In this study, we showed, for the first time, that the mRNA levels of TC1 were upregulated by mitogens (FBS/thrombin) and at least partially, through the ERK1/2 signaling pathway. Interestingly, the over-expression of TC1 promoted the $G_1$- to S-phase transition of the cell cycle, which was delayed by the deficiency of ERK1/2 signaling in fibroblast cells. Furthermore, the luciferase reporter assay indicated that the over-expression of TC1 significantly increased Cyclin D1 promoter-driven luciferase activity. Taken together, our findings revealed that TC1 was involved in the mitogen-activated ERK1/2 signaling pathway and positively regulated $G_1$- to S-phase transition of the cell cycle. Our results may provide a novel mechanism of the role of TC1 in the regulation of cell proliferation.

• 소성∙가공
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• 제19권7호
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• pp.411-415
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• 2010

A sandwich panel which is comprised of truss cores faced with solid face sheets is lightweight and multi-functional. So it is widely used to not only structural material but also heat transfer media in transportation field such as airplane, train and vessel. There are various core topologies such as pyramidal and tetrahedral truss, square honeycombs and kagome truss. The study focused on analytical approach to optimize compression and shear quality of the unit cell of PCM with pyramidal configuration. With various unit cell models which have the same core weight per unit area but different truss member angle, analytical solution for effective stress ($\bar{\sigma},\bar{\tau}$), peak stress ($\bar{\sigma}_{peak},\bar{\tau}_{peak}$) by yielding and buckling, relative density ($\bar{\rho}_c$) and effective stiffness ($\bar{E},\bar{G}$) have been computed and compared each other. With this approach, the most optimal core configuration was predicted. The result has become the efficient guidelines for the design of PCM core structure.

• Steel and Composite Structures
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• 제27권2호
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• pp.135-147
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• 2018

Quasi-static three-point bending tests on sandwich beams with expanded metal sheets as core were conducted. Relationships between the force and displacement at the mid-span of the sandwich beams were obtained from the experiments. Numerical simulations were carried out using ABAQUS/EXPLCIT and the results were thoroughly compared with the experimental results. A parametric analysis was performed using a Box-Behnken design (BBD) for the design of experiments (DOE) techniques and a finite element modeling. Then, the influence of the core layers number, size of the cell and, thickness of the substrates was investigated. The results showed that the increase in the size of the expanded metal cell in a reasonable range was required to improve the performance of the structure under bending collapse. It was found that core layers number and size of the cell was key factors governing the quasi-static response of the sandwich beams with lattice cores.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.525-526
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• 2006

A macro model for Savtchenko switching mode MRAM (toggling MRAM) cells which can be utilized to develop the core architecture and the peripheral circuitry is proposed, and a writing scheme suitable to the toggling characteristic is developed. The sensing and writing operations of the toggling MRAM adopting the macro model are verified by Spectre simulations.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.663-668
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• 2017

SOFC anode fabricated core-shell using machano-fusion method using core with submicron size Ni, nano size YSZ for shell. Using prepared core-shell, depending on the thickness of the shell, we studied how the characteristics of sintering and SOFC cell change by sintering the anode. The Ni-YSZ core-shell has a Ni core of 0.5 to $1.2{\mu}m$ over 2 to 7 YSZ of 15 to 20 nm is, and as the high speed mixing time increases, the YSZ number increases and the shell thickness becomes uniform increased. When the fuel electrode is manufactured with core-shell, it has superior sintering property, has grain of uniform size compared with the one synthesized by general mixing, the falling path is short, the conductors (electrons and ions) connection is excellent, the electrical conductivity has become excellent. The thicker the shell, the lower the electrical conductivity. When the thickness of shell ranged from 46 to 139 nm and 61 to 81 nm, the performance was the highest and the ASR was the smallest.

• Korean Chemical Engineering Research
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• 제57권1호
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• pp.111-117
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• 2019

기상으로 전달된 Ti 전구체가 열 플라즈마에서 고순도의 결정질 코어-$TiO_2$로 합성됨과 동시에 기판에 바로 증착시킬 수 있는 공정을 제시한다. 제조된 코어-$TiO_2$는 외부에 노출되지 않는 상태에서 원자층증착법(Atomic Layer Deposition, ALD)에 의하여 $Al_2O_3$로 코팅된다. 코어-$TiO_2$와 코팅된 쉘-$Al_2O_3$의 형태학적 특징은 transmission electron microscope (TEM) 및 transmission electron microscope - energy dispersive spectroscopy (TEM-EDS)를 통해 분석하였다. 제조된 코어-$TiO_2$/쉘-$Al_2O_3$ 나노입자의 전기적 특성은 염료감응 태양전지(dye-sensitized solar cell, DSSC)의 작동전극에 적용하여 평가하였다. Dynamic light scattering system (DLS), scanning electron microscope (SEM), X-ray Diffraction (XRD)을 통하여 코어-$TiO_2$의 평균입도, 성장속도 및 결정구조의 무게분율을 분석한 결과, 평균입도는 17.1 nm, 코어박막의 두께는 $20.1{\mu}m$이고 주 결정구조가 Anatase로 증착된 코어-$TiO_2$/쉘-$Al_2O_3$ 나노입자를 적용한 DSSC가 기존의 페이스트 방식으로 제작한 DSSC보다 더 높은 광효율을 보여준다. 기존의 페이스트방식을 활용한 DSSC의 에너지변환효율 4.99%에 비하여 선택적으로 조절된 코어-$TiO_2$/쉘-$Al_2O_3$ 나노입자를 작동전극으로 사용한 경우가 6.28%로 26.1% 더 높은 광효율을 보여준다.