• 대한금속재료학회지
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• 제48권9호
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• pp.847-855
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• 2010

The grain size of a cross-section of $8{\mu}m$-thick copper film was determined by electron backscatter diffraction analysis. Grain size distribution histogram showed the presence of a large fraction of small-sized grains, and the mean grain size was significantly affected by handling of them. A cut-off grain size, below which all grains are ignored as noise and eliminated for the calculation of the mean value, should be three or four times as large as the step size. Due to the presence of small grains, the linear intercept method derived larger mean grain size, which depends less sensitively on the cut-off grain size than the equivalent circle diameter method.

• Advances in nano research
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• 제14권2호
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• pp.155-164
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• 2023

Grain size in sheet metals in one of the main parameters in determining formability. Grain size control in industry requires delicate process control and equipment. In the present study, effects of grain size on the formability of steel sheets is investigated. Experimental investigation of effect of grain size is a cumbersome method which due to existence of many other effective parameters are not conclusive in some cases. On the other hand, since the average grain size of a crystalline material is a statistical parameter, using traditional methods are not sufficient for find the optimum grain size to maximize formability. Therefore, design of experiment (DoE) and artificial intelligence (AI) methods are coupled together in this study to find the optimum conditions for formability in terms of grain size and to predict forming limits of sheet metals under bi-stretch loading conditions. In this regard, a set of experiment is conducted to provide initial data for training and testing DoE and AI. Afterwards, the using response surface method (RSM) optimum grain size is calculated. Moreover, trained neural network is used to predict formability in the calculated optimum condition and the results compared to the experimental results. The findings of the present study show that DoE and AI could be a great aid in the design, determination and prediction of optimum grain size for maximizing sheet formability.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.89-92
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• 2009

As a class of materials, Ni-base superalloys are among the most difficult metal alloys to forge together with refractory metals and cobalt-base superalloys. The mechanical properties of Ni-base superalloys depend very much on grain size and the strengthening phases, $\gamma$' ($Ni_3$(Al,Ti)-type) and $\gamma$".($Ni_3$Nb-type). Especially, the control of grain size remains as a sole means for the control of mechanical properties. The grain size and distribution changes of the wrought superalloys during hot working and heat treatment are mainly controlled by the recrystallization and grain growth behaviors. In this presentation, prediction technology of grain size through the computer-aided process design, and numerical modeling for predicting the microstructure evolution of Ni-base superalloy during hot working were introduced. Also, some case studies were dealt with actual forming processes of Ni-base superalloys.

• 한국세라믹학회지
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• 제37권6호
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• pp.530-536
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• 2000

During the grain growth of the PZT thin films by selective nucleation method using PZT seed, it was found that the grain size was saturated with the annealing temperature. The saturation of grain size was analyzed by the interfacial energy which appeared during the crystallization. The factors affecting the saturation of grain size were found to be the interfacial energy between perovskite phase and pyrochlore phase, and PZT thin film and the bottom Pt electrode. When the ion damage was introduced to the grain-size saturated PZT thin films, further lateral growth was observed. Pt bottom electrode thickness was changed to control the interfacial energy between the PZT thin film and the Pt bottom electrode. When Pt thickness was increased, the grain size was also increased, because the lattice parameter of Pt films was increased with the thickness of the Pt films. The incubation time of nucleation was increased with the amount of the ion damage on the Pt films.

• 자동차안전학회지
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• 제13권3호
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• pp.20-25
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• 2021

Flexural resistance evaluation of FFC (Flexible Flat Cable) was performed according to the grain size of rolled copper foil by adding 0.1wt% silver (Ag) and electrodeposited copper foil by slitting method after heat-treatment. These methods are aimed at enhancing the flexural durability of the FFC by growing the grain size of copper foil. By increasing the grain size of the copper foil and minimizing the miss-orientation at grain boundaries, the residual stress at the grain boundaries of the copper foil is reduced and the durability of the FFC is improved. Maximizing an average grain size of copper foil can be got a good solution in order to enhance the durability of the FFC or FPCB (Flexible Printed Circuit Board).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.679-683
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• 2005

In this study, we investigate the characteristic of the poly-Si grain and morphology influenced by XeCl excimer laser system. The stable laser beam source is basic requested; the irradiation beam through optical lens module is more important which limit the grain size smaller than $0.5{\mu}m$. The homogenization lens designs control the poly-Si grain size; so we hardly get enlarge grain size by one laser irradiation scan.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.32.1-32.1
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• 2018

Novel soft magnetic materials can be achieved by altering material properties such as morphology, composition, crystallinity, and grain size of soft magnetic alloys. Especially, magnetic properties (i.e., saturation magnetization, coarcivity) of soft magnetics are significantly affected by grain boundaries which act as a control of magnetic domain wall movement. Thus, we herein develop a two-step electroless plating method to control morphology and grain size of FeCo films for excellent magnetic properties. Accordingly, the chemical composition to control the degree of polarization of FeCo alloys was altered by electroless deposition parameters; for example, electrolyte concentration and temperature. The grain size and crystallinity of FeCo alloys was dramatically affected by the reaction temperature because the grain growth mechanism dominantly occurs at $90^{\circ}C$ where as the neucleation only happens at $50^{\circ}C$. By simply controlling the temperature, the micron-sized FeCo grains embedded FeCo film was synthesized where the large grains allow high magnetization originated from larger magnetic domain with low corecivity and the nano-sized grains allow excellent soft magnetic properties due to the magnetic correlation length.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.179-180
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• 1999

• 한국재료학회지
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• 제13권6호
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• pp.352-359
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• 2003

In order to control the grain size, the spark plasma sintering technique is applied for the manufacturing of Cu-26.7Al-4.05AI(wt.%) shape memory alloy with pure Cu, Zn, and Al element powders. The sintering processes were carried out under different atmospheres. The sintered bodies were denser under Ar or Ar＋4%$H_2$gas atmosphere than under vacuum. With use of small-sized powders, a very small average grain size of 2∼3 $\mu\textrm{m}$ was obtained, but the single phase was not formed. With the large-sized powders the single austenitic phase was observed with the average grain size of $70∼72\mu\textrm{m}$. When the different size of raw powders was mixed, it is confirmed that the average grain size of the manufactured alloys was 15 $\mu\textrm{m}$ with single austenitic phase, but the distribution of grain size was not uniform.

• Rapid Communication in Photoscience
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• 제4권4호
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• pp.79-81
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• 2015

The influence of the grain size of the $CH_3NH_3PbI_3$ on the solar cell performance is investigated by controlling the ratio between $CH_3NH_3I$ and $PbI_2$ precursors. As the concentration of the precursors increased from 1.0M to 2.0M, the $CH_3NH_3PbI_3$ grain size increased from ~100nm to ~400nm. The solar cell utilizing the $CH_3NH_3PbI_3$ with large grain size shows improved photocurrent compared to the solar cell utilizing $CH_3NH_3PbI_3$ with small grain size, which is ascribed to the reduced recombination at the boundaries of grains.