• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.188-192
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• 2013

The magnetic interaction effect on the magnetic activation volume and area of electrodeposited CoPt magnetic films was investigated. The dipolar interaction was predominant interaction mechanism for all samples. And the interaction strength was increased with decreasing current density and increased with increasing sample thickness. Although the activation volumes of the samples fabricated at low current density were larger than those of the high current density samples, the sample thickness seemed to have little influence on the variation of activation volume. But it was found that the activation area was apparently affected by the magnetic interaction strength as well as the current density.

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.603-607
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• 2001

• Journal of the Korean Magnetics Society
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• v.26 no.6
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• pp.196-200
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• 2016

In this study the mechanisms of magnetization reversal and magnetic interaction effects on activation volumes for Sr-ferrite with different particle sizes are investigated. The activation volumes of C2 sample are larger than those of C3 sample in the range of low magnetic fields. But the fields above the coercivity of sample C2, the activation volumes of both samples are decreased linearly with increasing the applied magnetic field. These phenomena can be explained by the strengths of two critical fields representing the reverse domain nucleation field and the domain wall pinning field as well as the strength of dipolar interaction.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.240-240
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• 2003

탄소재료의 가스화속도는 근본적으로 활성자리의 수와 관련되어 있으며, 또한 가스화속도는 활성자리 뿐 아니라 확산제한에 따라 달라진다. 대부분의 탄소재료의 활성화 초기단계는 제한된 활성자리 때문에 반응속도는 느리고, 다음 단계는 총 활성자리가 증가하여 반응속도는 급격히 증가하고, 마지막으로 활성자리가 감소하여 활성화 속도는 감소한다. 이러한 sigmoidal특성을 나타내는 활성화 단계를 기공발달과정으로 설명하면, 활성화 초기에 탄소재료 내부에 이미 존재하는 닫힌 기공이 열리고, 일단 기공이 열리면 성장하게 된다. 이렇게 기공 수가 증가하는 것 뿐 아니라 기공 직경이 증가하여 활성화 과정이 진행될수록 비 표면적 및 기공부피는 증가하는데 이런 일련의 과정을 통하여 활성자리 수는 증가하고 또는 감소한다. 이렇게 기공이 발달하는 과정은 각각의 활성화 단계에서 탄소재료의 비 표면적 측정으로 알 수 있으며, 전반적인 산화속도 변화를 측정하여 반응단계를 추정하게 된다. 대부분의 연구자들은 반응 전체의 평균 산화속도를 측정한 후 활성화 에너지를 구하여 반응조절단계로 활성화 기구를 설명한다. 이 연구에서는 활성화 과정 중에 발생하는 중량감소 단계, 즉 각각의 활성화 단계에 따라 달라지는 반응속도상수를 측정하고, 반응단계별 활성화 에너지를 비교 해석하여 피치계 탄소섬유의 기공발달에 영향을 미치는 활성화 기구를 고찰하고자 하였다.

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.18-19
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• 2001

• Proceedings of the Korean Vacuum Society Conference
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• 2001.07a
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• pp.88-89
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• 2001

• Applied Biological Chemistry
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• v.33 no.1
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• pp.18-23
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• 1990

Seven varieties of soybeans(Paldal, Danyeob, Jangbaek, Baegun, Jangyeob and 2 cultivars of Local 1 and Local 2) were investigated to compare the water uptake properties and volume changes during soaking in water. The hydration properties showed that the equilibrated weight increase ratio decreased as the soaking temperature raised to higher than $40^{\circ}C$, while the initial water uptake rate increased upto $80^{\circ}C$. The increase in hydration showed a linear relationship with the square root of the soaking time at $4^{\circ}{\sim}60^{\circ}C$. Local 1 was the highest in water uptake rate constant while Local 2 was the lowest. The activation energy calculated was in the range of $3,246{\sim}4,694\;cal/mole$. The Jangbaek and Local 1 were the highest and the Paldal was the lowest in the rate of volume increase. The activation energy for volume increase was in the range of $3,310{\sim}4,190\;cal/mole$. The z-values calculated from volume change was a little higher than those obtained from weight change.

• Proceedings of the Korean Magnestics Society Conference
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• 2016.11a
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• pp.85-86
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• 2016

• Journal of the Korean Chemical Society
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• v.40 no.5
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• pp.327-332
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• 1996

The rates of solvolylsis of methyl chloroformate, phenyl chloroformate and 1-adamantyl derivatives in binary solvent mixtures have been measured by conductometric method at various temperatures and pressures. The activation parameters were estimated from the rate constants. The activation volume (${\Delta}V_o^{\neq}$) and the activation entropy (${\Delta}S^{\neq}$) are both negative, but the activation enthalpy (${\Delta}H^{\neq}$) is positive. This behavior is discussed in terms of electrostriction of solvation. The reactivities of these reactions were also estimated from the correlation of the activation volumes with the activation entropies. From these results, it could be estimated that the solvolyses of 1-adamantyl fluoroformate (in aqueous TFE) and 1-adamantyl tosylate have pathway involving unimolecular reaction, while the reaction of methyl chloroformate, phenyl chloroformate and 1-adamantyl fluoroformate (in aqueous alcohol) proceed through a bimolecular reaction.

• Elastomers and Composites
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• v.46 no.3
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• pp.245-250
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• 2011

The self diffusions and hole volumes of amorphous region of poly(acrylonitrile)-poly(vinyl chloride) fibers were investigated by experiments of stress relaxation. The experiments of stress relaxation were carried out using the tensile tester with the solvent chamber. The flow parameters of filament fibers were obtained by applying the experimental stress relaxation curves to the theoretical equation of stress relaxation. From the flow parameters, the hole volumes, self diffusions, viscosities and thermodynamic parameters of solid polymers were calculated. It was observed that the flow parameters of these samples are directly related to the hole volumes, self diffusions and flow activation energies of flow segments.