• Korean Journal of Adult Nursing
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• v.21 no.2
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• pp.155-166
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• 2009

Purpose: This study developed and evaluated a systematic intervention among medical ICU nurses for preventing ventilator-associated pneumonia (hereafter VAP). Methods: A VAP prevention program was proposed based on a literature review, revised to fit the target situation, and validated. It was composed of one-time interventions including education, pamphlets, hand cultures, and a quiz event, as well as repeated interventions such as posters, reminders, posting hand culture results, and performance feedback. A simulated control group pretest-posttest design was used to verify the effectiveness of the VAP control program. The incidence of VAP among ICU patients was measured both during 3 months before (n=80) and during 3 months after (n=75) intervention. Results: The VAP prevention program's effectiveness, with a pre-intervention VAP rate of 17.38 and post-intervention rate of 11.04 per 1,000 ventilator days, showed a clinical tendency to decrease, but the difference was not statistically significant (p=.750). Conclusion: A VAP prevention program of multiple interventions can be useful in decreasing the VAP rate. Given that the monthly decrease in the VAP rate was not considered statistically significant, long-term research needs to be done. Additionally, since this study targeted only nurses, it is suggested that future research targets other health care workers who can influence VAP rates.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.194-200
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• 2004

Thermal energy performance of a brazed plate heat exchanger has been evaluated experimentally. The effects of plate pitch as well as chevron angle of a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in the wide range as mass flow rates in detail. This problem is of particular interest in the design of a plate heat exchanger. The results obtained indicate that both heat transfer rate and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer rate is increased with a decrease in the plate pitch while the heat transfer is decreased with a decrease in the chevron angle. Friction factor correlations are suggested based on the measured pressure drop and effectiveness of plate heat exchangers are also compared.

• Journal of Families and Better Life
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• v.28 no.1
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• pp.1-11
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• 2010

The purpose of this study is to compare the cognition of SIDS as the first step for decreasing the SIDS death rate for the infant and for activity of infant-care in Korea. Participants were 409 child care center directors and 146 parents from 500 child care center directors and 200 parents who using child care center facilities for their children in Seoul. For analysis of research questions, frequencies, Cronbach $\alpha$, t-test,One-way ANOVA, Scheffee test were used with SPSSWIN 15.0. Through this study, we find the child care center directors have good cognition for it, but their effort for SIDS prevention is limited, because they don't have any official prevention education from authorized training center. Even though the parents have a low awareness for SIDS prevention than child care center directors, but they have high score in endeavor for SIDS precaution. Both child care center directors and parents want to receive systematic information from government side. Our infant should have a opportunity to grow up health and stability from reducing the risk of SIDS. In western countries such as U.S.A., U.K. and Japan have studied to decrease the SIDS death rate from thirty years ago, they have already government and social organization for preventing the SIDS. Nowadays, as you know well, our country birth-rate is falling by 1.08, therefore, it is important to decrease the infant death rate for keeping with our population. Also, it is relevant to the child-welfare and the child-safety and more better the child-care.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.438-446
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• 1994

The effect of various thermomechanical treatments on the structure and rheological behaviour of Al-6.2wt%Si alloy in its solidification range were investigated using a Searle type high temperature viscometer. During continuous cooling, the viscosity increases gradually with increasing fraction of solidified alloy, until a critical fraction of solidified alloy is reached above which the viscosity sharply increases. The viscosity of the slurry, at a given volume fraction wolid, decreased with increasing shear rate. The size and morphology of primary solid particles during stirring is influenced strongly by shear rates, cooling rates, volume fraction and stirring time of solid. Morphological changes during stirring as a function of solid volume fractions, shear rate and processing time were also reported. In this study, the size of primary solid particles in these alloys consistently increases and the it`s aspect ratio decrease with the increase in fraction solid and decrease in shear rate. Crystal morphology changes from rosette type to spheroid type with the increase in shear rate and solid fraction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.61-65
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• 2008

This study, having combined and displaced blast furnace slag("BS" hereinafter) known as admixture material that delays hydration reaction with coarse particle cement("CC" hereinafter) collected in particle classification method during ordinary portland cement("OPC" hereinafter), reviewed the hydration heat characteristics affecting the concrete. To reduce hydration heat, the study plain-mixed which used 100% OPC for W/B 50% level 1, displaced CC at level 3 of 25%, 50% and 75% for OPC, and by displacing BS with admixture material at level 5 of 0%, 20%, 40%, 60% and 80% for cement(OPC+CC), experimented totally 16 batches. As a result of experiment, in the case of flow, the more CC displacement rate increased, the more it tended to decrease, and the more BS displacement rate increased, the more it decreased. Also, as for simple adiabatic temperature rise by the CC and BS displacement rates, it decreased as displacement rate increased, and particularly in the case of displaced BS of 80%, It showed temperature reduction effect of about 63% companing with plain. Compressive strength decreased in proportion to displacement rate, however strength reduction increment was shown to decrease with age progress.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.879-881
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• 1999

Radical and ion densities in a CF4 plasma have been calculated as a function of input power density. 9as pressure and feed gas flow rate using simple 0 dimensional global model. Fluorine atom is found to be the most abundant neutral particle. Highly fragmented species such as CF and CF+ become dominant neutral and ionic radical at the high power condition. As the pressure increases. ion density increases but ionization rate decreases due to the decrease in electron temperature. The fractional dissociation of CF4 feed gas decreases with pressure after increasing at the low pressure range. Electron density and temperature are almost independent of flow rate within calculation conditions studied. The fractional dissociation of CF4 monotonically decreases with flow rate. which results in increase in CF3 and decrease in CF density. The calculation results show that the SiO2 etch selectivity improvement correlates to the increase in the relative density of fluorocarbon ion and neutral radicals which has high C/F ratio.

• Korean Journal of Materials Research
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• v.2 no.2
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• pp.133-142
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• 1992

The slow strain-rate test($1{\times}10^{-4}~1{\times}10^{-7}sec^{-1}$) was performed to understand the tensile properties of chopped strand glass mat/polyester composite in air and synthetic sea water. (pH 6.0, 8.2, 10.0) For the tested composite subjected to tensile loading in air and synthetic sea water (ph 6.0, 8.2, 10.0), the tensile properties are a little decreased as strain rate decrease and a little decrease in stiffness is observed in $1{\times}10^{-7}sec^{-1}$. The tensile properties were some changed in case the pH value in synthetic sea water is varied.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.108-113
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• 1999

Background: There is some concern that the administration of epidural analgesia for pain relief during labor increases the likelihood of cesarean delivery. But, several investigators showed a decrease in the rate of emergency cesarean delivery after epidural analgesia. The purpose of this study was to compare the emergency cesarean rate between the two groups with and without epidural analgesia. Methods: We reviewed retrospectively the medical records for 7846 parturients admitted our hospital between January 1, 1995 and December 31, 1996 and whose attending physician anticipated a normal labor and vaginal delivery. The number of parturients with epidural analgesia using 0.25% bupivacaine with fentanyl were 2839 and parturients without epidural analgesia were 5017. Results: An administration of epidural analgesia was not associated with the incidence of cesarean rate. 149 (5.25%) of 2839 parturients in epidural group and 371 (7.31%) of 5017 parturients in non-epidural group underwent emergency cesarean section. Conclusions: Our retrospective study has shown that an administration of epidural analgesia neither decrease nor increase in the rate of emergency cesarean delivery when compared with a non-epidural analgesia.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.199-205
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• 2013

The mechanical properties and microstructures of aluminum-matrix composites fabricated by the dispersion of fine alumina particles less than $20{\mu}m$ in size into 6061 aluminum alloys are investigated in this study. In the as-quenched state, the yield stress of the composite is 40~85 MPa higher than that of the 6061 alloy. This difference is attributed to the high density of dislocations within the matrix introduced due to the difference in the thermal expansion coefficients between the matrix and the reinforcement. The difference in the yield stress between the composite and the 6061 alloy decreases with the aging time and the age-hardening curves of both materials show a similar trend. At room temperature, the strain-hardening rate of the composite is higher than that of the 6061 alloy, most likely because the distribution of reinforcements enhances the dislocation density during deformation. Both the yield stress and the strain-hardening rate of the T6-treated composite decrease as the testing temperature increases, and the rate of decrease is faster in the composite than in the 6061 alloy. Under creep conditions, the stress exponents of the T6-treated composite vary from 8.3 at 473 K to 4.8 at 623 K. These exponents are larger than those of the 6061 matrix alloy.

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.717-722
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• 2012

Fluoride can be easily found in semiconductor and display industry. However, there is a lack of research for its effects on the related wastewater treatment. The objective of this study is to evaluate the microbial inhibitory effect by fluoride injection. The research entailed the assessment of removal efficiency of $TCOD_{Cr}$ according to the fluoride concentration and also the Specific Oxygen Uptake Rate (SOUR) was measured. The laboratory scale reactor was prepared and operated with the fluoride concentrations of 0, 10, 50, 100, and 200 mg/L based on concentrations frequently occurring in the wastewater. The results from this study showed that, as the fluoride concentration increase, the Specific Substrate Utilization Rate (SSUR) tend to decrease as expected. Also, the increase in fluoride concentrations resulted in the decrease in SOUR. It is determined that fluoride injection affects the microbial activity. Especially, The addition of above 200 mg/L fluoride into reactor caused rapidly decreased SSUR and SOUR due to the inhibitory effects of fluoride.