• Textile Coloration and Finishing
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• v.23 no.4
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• pp.250-256
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• 2011

In this work, the effects of surfactant and solvents, such as benzyl alcohol and n-propyl alcohol, on the human hair dyeing with acid dye was investigated including the amount of dyes in hair according to dyeing time, temperature, and pH. And the damage of dyed hair was assessed by water retention, protein release, and SEM images of the dyed hairs. By adding benzyl alcohol in acid dyeing, the dyeing rate was increased and the dyeing equilibrium was established at early stage. The water retention of the dyed hair was increased and the protein release of the dyed hair was decreased. Therefore the hair was damaged less during the dyeing.

• International Journal of Reliability and Applications
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• v.2 no.3
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• pp.147-160
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• 2001

The reliability of computer software is of prime importance for all developers of software. The complicated nature of detecting and removing faults from software has led to a plethora of models for reliability growth. One of the most basic of these is the Jelinski Moranda model, where it is assumed that there are N faults in the software, and that in testing, bugs (or faults) are encountered (and removed when defected) according to a stochastic process at a rate which at a given point in time is proportional to the number of bugs remaining in the system. In this research, we consider the possibility that imperfect repair may occur in any attempt to remove a detected bug in the Jelinski Moranda model. We let p represent the probability that a fault which is discovered or detected is actually perfectly repaired. The possibility that the probability p may differ before and after release of the software is also considered. The distribution of both the number of bugs detected and perfectly repaired in a given time period is studied. Cost models for the development and release of software are investigated, and the impact of the parameter p on the optimal release time minimizing expected costs is assessed.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.31-34
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• 1997

A new method for the prevention of foreign body-associated infections by controlled release of antibiotic was developed. The polyurethane (PU) matrix containing rifampicin was immobilized with hydrophilic photoreactive polyallylamine (PPA) containing azidophenyl groups. The rifampicin release characteristics and the long-lasting antimicrobial activities of the new material was compared with rifampicin-containing PU matrix without PPA membrane. The release rate of antibiotic from rifampicin-containing PU with PPA membrane significantly decreased as the thickness of PPA membrane was increased. The PPA-immobilized rifampicin-containing PU discs immersed in the PBS for 47 days had an efficient antimicrobial activity against both S. aureus and S. epidermidis.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2159-2167
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• 2006

In order to find out a physical quantity which controls the fatigue life of a structure and to predict the fatigue life of tires, a finite element simulation methodology to use the cracking energy density (CED) and the virtual crack closure technique (VCCT) was proposed and applied to three different tires of a similar size. CED was calculated to predict the location of a crack initiation, and VCCT was used to obtain the strain energy release rate (SERR) at the tip of an initiated crack. Finite element simulations showed that SERR oscillated in the circumferential direction with its minimum occurring just before the contact zone and its maximum occurring just after the center of the contact zone, and SERR was affected significantly by the frictional force acting on the crack surface. In addition, a durability test was conducted to measure the fatigue life of the three tires. The comparison of SERR values with the test data revealed that the fatigue life increased as the amplitude of SERR decreased or as the R-ratio of SERR increased.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.39-44
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• 2005

The effects of aging of PSF/AS4 laminates on fatigue was studied using the new energy release rate analysis. The analysis by the variational mechanics has been useful in providing fracture mechanics interpretation of matrix microcracking in cross-ply laminates. This paper describes the changes of the critical energy release rate (microcracking toughness) according to the aging period under fatigue loading. The master plot by modified Paris-law gives a characterization of a material system's resistance to microcrack formation. PSF $[0/90_{s}]_{s}$ laminates were aged at four different temperature based on the glass transition temperature for 0 to 60 days. At all temperatures, the toughness decreased with aging time. The decrease of the toughness at higher temperature was faster than at lower temperature. To assess the effects of aging on fatigue, the unaged laminates were compared with the laminates which had been aged for 60 days at 170$^{\circ}C$ near 180 $^{\circ}C$ t$_g$. The slope of dD/dN versus ${\Delta}G_m$. of the aged laminates was lower than that of the unaged laminates. There was a significant shift of the aged data to formation of microcracks at the lower values of ${\Delta}G_m$.

• The Korean Journal of Physiology
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• v.24 no.2
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• pp.269-280
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• 1990

The purpose of the present experiment was to determine the functional subclassification of renal adenosine receptor fer the hemdynamic, excretory and secretory functions in unanesthetized rabbits. Adenosine antagonist, 8-phenyltheophylline (8-PT) or theophylline, was infused into the left renal artery followed by an infusion of adenosine agonist, cyclohexyladenosine (CHA) or 5'-N-ethylcarboxamidoadenosine (NECA). Intrarenal arterial infusion of CHA or NECA caused decreases in urine volume, glomerular filtration rate, renal plasma flow and excreted amount of electrolytes and renin release in a dose-dependent manner. Dose-response curves in renal function by CHA or NECA was similar and shifted to the right with pretreatment of 8-PT or theophylline. No significant differences in renal response to CHA and NECA in antagonist-treated rabbits were observed. However, the decrease in renin secretion rate was not affected by the adminstration of adenosine antagonists. These results suggest that the renal effect of adenosine receptor agonists appears by way of specific adenosine receptor, but which is not functionally subclassified in the rabbit.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.410-423
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• 2019

Fire suppression using a water mist nozzle directly above an n-Heptane pool in a fire compartment with a door opening was numerically investigated using the Fire Dynamics Simulator (FDS) for the purpose of application in nuclear power plants. Input parameters for the numerical simulation were determined by experimental measurements. Water mist was activated 10 s after the fire began. The sensitivity analysis was conducted for three input parameters: total number of cubic cells of 6032-2,926,400, droplets per second of 1000-500,000, and extinguishing coefficient of 0-100. In a new simple calibration method of this study, the extinguishing coefficient yielding the fire suppression time closest to that measured by experiments was found for use as the FDS simulation input value. When the water mist jet flow made contact with the developed fire, the heat release rate instantaneously increased, and then rapidly decreased. This phenomenon occurred with a displacement of the flame near the liquid fuel pool. Changing the configuration of the door opening with different aspect ratios and opening ratios had impact on the maximum value of the heat release rate due to the flame displacement.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.679-687
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• 2007

Nanoscale zero valent ion (nZVI) technology is emerging as an innovative method to treat contaminated groundwater. The activity of nZVI is very high due to their high specific surface area, and supporting this material can help to preserve its chemical nature by inhibiting oxidation. In this study, nZVI particles were attached to granular ion-exchange resin through borohydride reduction of ferrous ions, and chemical reduction of nitrate by this material was investigated as a potential technology to remove nitrate from groundwater. The pore structure and physical characteristics were measured and the change by the adsorption of nZVI was discussed. Batch tests were conducted to characterize the activity of the supported nZVI and the results indicated that the degradation of nitrate appeared to be a pseudo first-order reaction with the observed reaction rate constant of $0.425h^{-1}$ without pH control. The reduction process continued but at a much lower rate with a rate constant of $0.044h^{-1}$, which is likely limited by mass transfer. To assess the effects of other ions commonly found in groundwater, the same experiments were conducted in simulated groundwater with the same level of nitrate. In simulated groundwater, the rate constant was $0.078h^{-1}$ and it also reduced to $0.0021h^{-1}$ in later phase. The major limitation in application of ZVI for nitrate reduction is ammonium production. By using a support material with ion exchange capacity, the problem of ammonium release can be solved. The ammonium was not detected in the batch test, even when other competitive ions such as calcium and potassium existed.

• Polymer(Korea)
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• v.26 no.5
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• pp.670-679
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• 2002

1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine) is one of the effective chemotherapeutic agents which has been used clinically for treating malignant glioma. Poly(D,L-lactide-co-glycolide) (PLGA, molecular weight: 20000 g/mole. mole ratio of lactide to glycolide 75 : 15) is a well known biodegradable polymer used as a drug carrier for drug delivery system. In this study, we investigated the BCNU release behaviour of BCNU-loaded PLGA wafers containing poly (N-vinylpyrrolidone) (PVP) or polyethyleneoxide (PEO) and the effect of hydrophilic polymers incoporated in the wafers. BCNU-loaded PLGA microparticles with or without hydrophilic polymers were prepared by a spray drying method and fabricated into wafers by direct compression. Encapsulation efficiency of BCNU-loaded PLGA microparticles containing PVP and PEO was 85 ∼ 97% and crystallinity of BCNU encapsulated in PLGA decreased significantly initial release amount and release rate of BCNU increased with the increasing PVP or PEO amount. Morphological change and mass loss of wafers during the release test were confirmed that hydration and degradation of PLGA would be facilitated with an increase of hydrophilic polymers.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.251-259
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• 2006

For practical application on the HCCI engine, the solution of subjects, such as control of auto-ignition timing and avoidance of knocking, is indispensable. This study focused on the technique of controlling HCCI combustion appropriately, changing the mixture ratio of two kinds of fuel. Methane and DME/n-Butane were selected as fuels. The influences, which the mixing ratio of two fuels does to ignition timing, ignition temperature, rate of heat release and oxidation reaction process, were investigated by experiment with 4-stroke HCCI engine and numerical calculation with elementary reactions.