• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.21-31
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• 1997

Toluene, n-hexane, and methyl ethyl ketone(MEK) were exposed to the activated carbon fiber(ACF) and 3M(Model 3500) diffusive samplers under low and high humidity levels. In order to evaluate these two samplers, the sampling capacity, sampling rate, reverse diffusion, and storage stability were obtained. At low humidity level($8{\pm}3%RH$), the adsorption amount of all three organic vapors to the ACF diffusive sampler showed a positive linear relationship up to 8 hours. However, at high humidity level($90{\pm}5%RH$), n-hexane and MEK maintained a positive linear relationship up to 1.5 hrs, but decreased in their adsorption amounts afterwards. On the other hand, the adsorption amount of n-hexane, MEK, and toluene to 3M diffusive sampler showed almost a positive linear relationship up to 8 hours at both humidity levels. At low humidity level, there was almost no reverse diffusion for both 3M and ACF diffusive samplers. However, when the ACF diffusive sampler was used at high humidity level, there was about 52.63% of MEK sample loss and about 92.59% of n-hexane sample loss. The storage stabilities of the ACF and 3M diffusive samplers were both relative stable except for MEK. In the case of MEK, the difference between the analysis of the organic vapor right after the sampling and that of 3 weeks later at room temperature was 45% for the ACF diffusive sampler and 18% for the 3M diffusive sampler. Since the storage stability of the samples stored in a refrigerator was relatively stable, they need to be refrigerated until the analysis is done.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.164-170
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• 2005

To improve functional properties of food proteins, homologous or heterologous ${\beta}-casein$ and 11S globulin(glycinin) from animal and vegetable proteins, respectively, were bio-hybridized using transglutaminase(MTGase). Susceptibility was confirmed by SDS-PAGE, particle size analyzed, and emulsion stability tested using Reddy and Fogler method, To determine how bio-hybridized protein influences emulsion stability, protein bound on oil droplet was investigated using Scanning Electron Microscopy (SEM). formation of bio-hybridized protein band was detected among homologous and heterologous proteins, with heterologous protein forming weak band in oligomer form. Homologous ${\beta}-casein$ protein showed high emulsion stability, while homologous glycinin showed almost no stability. Stability of heterologous ${\beta}-casein$ and glycinin protein was higher than that of glycinin. SEM photographs showed even distribution of bio-hybridized proteins on oil droplet improved stability.

• Bulletin of the Korean Mathematical Society
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• v.48 no.4
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• pp.673-688
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• 2011

Let $n{\geq}2$ be an even integer. We investigate that if an odd mapping f : X ${\rightarrow}$ Y satisfies the following equation $2_{n-2}C_{\frac{n}{2}-1}rf\(\sum\limits^n_{j=1}{\frac{x_j}{r}}\)\;+\;{\sum\limits_{i_k{\in}\{0,1\} \atop {{\sum}^n_{k=1}\;i_k={\frac{n}{2}}}}\;rf\(\sum\limits^n_{i=1}(-1)^{i_k}{\frac{x_i}{r}}\)=2_{n-2}C_{{\frac{n}{2}}-1}\sum\limits^n_{i=1}f(x_i),$ then f : X ${\rightarrow}$ Y is additive, where $r{\in}R$. We also prove the stability in normed group by using shadowing property and the Hyers-Ulam stability of the functional equation in Banach spaces and in Banach modules over unital C-algebras. As an application, we show that every almost linear bijection h : A ${\rightarrow}$ B of unital $C^*$-algebras A and B is a $C^*$-algebra isomorphism when $h(\frac{2^s}{r^s}uy)=h(\frac{2^s}{r^s}u)h(y)$ for all unitaries u ${\in}$ A, all y ${\in}$ A, and s = 0, 1, 2,....

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.54-60
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• 2010

This paper presents a new algorithm for determining generator operation point for maintaining stability considering generator faults in Jeju-Haenam HVDC system. As the HVDC system consumes reactive power for the transmission of active power substantially, compensation of reactive power is essential. And the HVDC system is operated on frequency control mode. That is to say, the HVDC system almost manages system frequency. Therefore, we recognized that the Jeju system could be unstable if the reactive power consumed by the HVDC is insufficient when out-of-step occurs with large generators. When the solution of power flow analysis does not converge due to the unstable system phenomenon, we have difficulty in establishing countermeasures as the post-fault information is not available. In this paper, for the purpose of overcoming this difficulty in establishing countermeasures, we introduce the CPF(Continuation Power Flow) algorithm. This paper suggests an algorithm for calculating the output limitation of the generator to maintain the stability in case of generator fault in the Jeju system.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.2
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• pp.287-301
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• 2011

Let X and Y be vector spaces. It is shown that a mapping $f\;:\;X{\rightarrow}Y$ satisfies the functional equation $$(\ddag)\hspace{50}dk\;f\left(\frac{\sum_{j=1}^{dk}x_j}{dk}\right)=\displaystyle\sum_{j=1}^{dk}f(x_j)$$ if and only if the mapping $f$ : X ${\rightarrow}$ Y is Cauchy additive, and prove the Cauchy-Rassias stability of the functional equation ($\ddag$) in Banach modules over a unital $C^{\ast}$-algebra. Let $\mathcal{A}$ and $\mathcal{B}$ be unital $C^{\ast}$-algebras. As an application, we show that every almost homomorphism $h\;:\;\mathcal{A}{\rightarrow}\mathcal{B}$ of $\mathcal{A}$ into $\mathcal{B}$ is a homomorphism when $h((k-1)^nuy)=h((k-1)^nu)h(y)$ for all unitaries $u{\in}\mathcal{A}$, all $y{\in}\mathcal{A}$, and $n$ = 0,1,2,$\cdots$. Moreover, we prove the Cauchy-Rassias stability of homomorphisms in $C^{\ast}$-algebras.

• Wind and Structures
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• v.29 no.1
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• pp.15-32
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• 2019

Much advancement has been made in wind power due to modern technological developments. The wind energy technology is the world's fastest-growing energy option. More power can be generated from wind energy by the use of new design and techniques of wind energy machines. The geographical areas with suitable wind speed are more favorable and preferred for wind power deployment over other sources of energy generation. Today's wind turbines are mainly the horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). HAWTs are commercially available in various sizes starting from a few kilowatts to multi-megawatts and are suitable for almost all applications, including both onshore and offshore deployment. On the other hand, VAWTs finds their places in small and residential wind applications. The objective of the present work is to review the technological development, available sizes, efficiencies, structural types, and structural stability of VAWTs. Structural stability and efficiencies of the VAWTS are found to be dependent on the structural shape and size.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1187-1190
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• 2005

The ramp reset driving method proposed in [1] has been widely adopted because of its stability and high contrast ratio. However, when the conventional ramp reset method is used in PDPs of higher resolution, the long required time for reset often becomes a problem. In this paper, a new driving method that requires much less reset time and that significantly improves the contrast ratio is introduced. Using this new driving method, the required time for reset could be reduced to 150us from 350us of the conventional ramp reset method, and the contrast ratio is almost infinite because the luminance of the off-cell is almost zero.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.3
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• pp.101-109
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• 1997

We propose a new concept of hydrogen absorbing alloy, "Laves phase related BCC solid solution". It was firstly found among the phases tormed in multicomponent nominal $AB_2$ alloys which consisted of Zr and Ti for the A metal site and 5A, 6A and 7A transition metals for the B metal sites. In these alloys a BCC solid solution often coexisted with a Laves phase. It showed stability of hydrides and reaction kinetics almost identical to intermetallics such as Laves phase alloys. We prepared an almost pure "Laves phase related BCC solid solution" and found that it had a large hydrogen capacity (more than 2 mass%) and fast hydrogen absorption and desorption kinetics at ambient temperature and pressure. This new hydrogen absorbing alloy may open a new era of hydrogen related application such as hydrogen vehicles.

• Journal of the Korean Mathematical Society
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• v.40 no.1
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• pp.29-40
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• 2003

Let K be a nonempty closed bounded convex subset of an arbitrary smooth Banach space X and T : KlongrightarrowK be a strictly hemi-contractive operator. Under some conditions we obtain that the Mann iteration method with errors both converges strongly to a unique fixed point of T and is almost T-stable on K. The results presented in this paper generalize the corresponding results in [l]-[7], [20] and others.

• Journal of the Korean institute of surface engineering
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• v.28 no.4
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• pp.243-254
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• 1995

The fabrication process of Cu-base anode for replacing Ni-base anode of molten carbonate fuel cell was investigated. Electrochemical performance and thermal stability of Cu-base anode were also investigated. Green sheet was prepared by mixing Cu and Ni powder with 1.5wt% methylcellulose and 100wt% water. The pore-size distribution of the Cu-base anode sintered at $800^{\circ}C$ for 30min showed almost uniform pore-size ranging from 4 to 20$\mu\textrm{m}$ and it was considered suitable for MCFC anode. Cu-Ni anode containing between 35 to 50wt% Ni exhibited current density of 111mA/$\textrm{cm}^2$ at 100mV overpotential and it was almost the some value for pure Ni anode. The sintering resistance of Cu-Ni increased with an increase of Ni addition. It was considered that the increase of sintering resistance was due to the decrease of diffusion rate of Cu and Ni with increasing the addition of Ni in Cu-Ni alloy.