• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.2068-2076
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• 2005

The influence of oxygen concentration and CO$_{2}$ as diluent in oxidizer side on soot characteristics was studied by Laser Induced Incandescence, Time Resolved LII and Transmission Electron Microscopy photography in non-premixed co flowing flames. Through the comparison of TEM photographs and the decay rate of LII signal, suitable two delay times of TIRE-LII method and signal sensitivity ($\Delta$S$_{TIRE-LII/) were determined. The effects of O$_{2}$ and CO$_{2}$ as diluent in oxidizer side on soot formation are investigated with these calibrated techniques. The O$_{2}$+CO$_{2}$, N$_{2}$, and [Ar+CO$_{2}$] mixture in co-flow were used to isolate CO2 effects systematically. The number concentration of primary particle and soot volume fraction abruptly decrease by the addition of CO$_{2}$ to the co-flow. This suppression is resulted from the short residence time in inception region because of the late nucleation and the decrease of surface growth distance by the low flame temperature due to the higher thermal capacity and the chemical change of CO$_{2}$ including thermal dissociation. As the oxygen concentration increases, the number concentration of soot particles at the inception region increases and thus this increase of nucleation enhances the growth of soot particle.

• Advanced Composite Materials
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• v.16 no.4
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• pp.269-282
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• 2007

Fully biodegradable high strength composites or 'advanced green composites' were fabricated using yearly renewable soy protein based resins and high strength liquid crystalline cellulose fibers. For comparison, E-glass and aramid ($Kevlar^{(R)}$) fiber reinforced composites were also prepared using the same modified soy protein resins. The modification of soy protein included forming an interpenetrating network-like (IPN-like) resin with mechanical properties comparable to commonly used epoxy resins. The IPN-like soy protein based resin was further reinforced using nano-clay and microfibrillated cellulose. Fiber/resin interfacial shear strength was characterized using microbond method. Tensile and flexural properties of the composites were characterized as per ASTM standards. A comparison of the tensile and flexural properties of the high strength composites made using the three fibers is presented. The results suggest that these green composites have excellent mechanical properties and can be considered for use in primary structural applications. Although significant additional research is needed in this area, it is clear that advanced green composites will some day replace today's advanced composites made using petroleum based fibers and resins. At the end of their life, the fully sustainable 'advanced green composites' can be easily disposed of or composted without harming the environment, in fact, helping it.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1422-1436
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• 1997

Numerical investigations were conducted to study the convective phenomena of an initially stably stratified salt water solution with lateral heating in a uniformly rotating annulus. The method of investigation is the finite difference analysis of the basic conservation equation for an axisymmetric, unsteady, double-diffusive convection and calculation is made for R $a_{\eta}$=2*10$^{5}$ and Ta=10$^{7}$ ~ 2.5*10$^{8}$ . Formation of layered flow structure, merging process of layers, the corresponding temperature and concentration distributions, Nu variation with time are examined. Numerical results show that in each layer, the temperature profile looks 'S'-shaped and the concentration profile is uniform due to the convective mixing. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly. As the effect of the rotation increases, the generation of rolls at hot wall, the formation and merging of layers are delayed. The average Nu shows the trend of conduction heat transferees the effect of the rotation increases.n increases.

• Advances in nano research
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• v.9 no.4
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• pp.221-235
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• 2020

The following composition establishes a nonlocal strain gradient plate model that is essentially related to mass sensors laying on Winkler-Pasternak medium for the vibrational analysis from graphene sheets. To achieve a seemingly accurate study of graphene sheets, the posited theorem actually accommodates two parameters of scale in relation to the gradient of the strain as well as non-local results. Model graphene sheets are known to have double variant shear deformation plate theory without factors from shear correction. By using the principle of Hamilton, to acquire the governing equations of a non-local strain gradient graphene layer on an elastic substrate, Galerkin's method is therefore used to explicate the equations that govern various partition conditions. The influence of diverse factors like the magnetic field as well as the elastic foundation on graphene sheet's vibration characteristics, the number of nanoparticles, nonlocal parameter, nanoparticle mass as well as the length scale parameter had been evaluated.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.1-9
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• 2014

The inverse Rayleigh model distribution and Rayleigh distribution model were widely used in the field of reliability station. In this paper applied using the finite failure NHPP models in order to growth model. In other words, a large change in the course of the software is modified, and the occurrence of defects is almost inevitable reality. Finite failure NHPP software reliability models can have, in the literature, exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, proposes the inverse Rayleigh and Rayleigh software reliability growth model, which made out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on mean square error (MSE) and coefficient of determination($R^2$), for the sake of efficient model, were employed. In order to insurance for the reliability of data, Laplace trend test was employed. In many aspects, Rayleigh distribution model is more efficient than the reverse-Rayleigh distribution model was proved. From this paper, software developers have to consider the growth model by prior knowledge of the software to identify failure modes which can helped.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.2
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• pp.139-149
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• 2013

As the importance of technology forecasting while countries and companies manage the R&D project is growing bigger, the methodology of technology forecasting has been diversified. One of the forecasting method is patent analysis. This research proposes quick forecasting process of emerging technology based on keyword approach using text mining. The forecasting process is following: First, the term-document matrix is extracted from patent documents by using text mining. Second, emerging technology keyword are extracted by analyzing the importance of word from utilizing mean values and standard deviation values of the term and the emerging trend of word discovered from time series information of the term. Next, association between terms is measured by using cosine similarity. finally, the keyword of emerging technology is selected in consequence of the synthesized result and we forecast the emerging technology according to the results. The technology forecasting process described in this paper can be applied to developing computerized technology forecasting system integrated with various results of other patent analysis for decision maker of company and country.

• Journal of Korean Public Health Nursing
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• v.27 no.3
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• pp.539-550
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• 2013

Purpose: The objectives of this study were to investigate the level of meaning in life(MIL) among university students as well as identify the effects of death perception, including good death and concerns about dying, and self-esteem on MIL. Methods: A questionnaire survey was developed and carried out using a convenient sampling method (N=301). Data were analyzed by applying descriptive statistics, t-test, ANOVA, Duncan test, Pearson's correlation coefficient, and stepwise multiple regression. Results: The average score for MIL was 4.70 on a 7-point scale. The factor of purpose of life received highest score among all factors in MIL. MIL was positively correlated with age, good death, and self-esteem. However, concerns about dying were negatively correlated with MIL. MIL showed a strong association with self-esteem(r=.72). Specifically, self-esteem(${\beta}$=.608), satisfaction of school life(${\beta}$=.190), relationship with parents(${\beta}$=.180), good death(${\beta}$=.080), school grades(${\beta}$=.078), and age(${\beta}$=.074) all significantly influenced MIL. These variables accounted for 61.0% of the total variance. Conclusion: The results show that self-esteem is an important factor for MIL among university students. Therefore, self-esteem should be carefully considered to increase their MIL. These research findings can be utilized to support programs such as counseling and education of university students.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.52-57
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• 2008

The short-term high temperature creep rupture behavior of Ni-based Alloy718 steel was investigated at the elevated temperatures range of 550 to $700^{\circ}C$ under constant stress conditions. The creep rupture characteristics such as creep stress, rupture time, steady state creep rate, and initial strain were evaluated. Creep stress has a quantitative correlation between creep rupture tim and steady state creep rate. The stress exponents (n, m) of the experimental data at 550, 600, 650 and $700^{\circ}C$ were derived as 33.5, -24.9, 26.1, -21.2, 16.8, -12.8 and 10, -8.2, respectively. The stress exponent decreased with increasing creep temperature. The creep lift prediction was derived by the Larson-Miller parameter (LMP) method and the resultant equation was obtained as follows: T($logt_r$+20)=-0.00252 ${\sigma}^2$-1.377${\sigma}$+-22718.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1988-1990
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• 1996

In this work, we have grown or evaporated thermal oxide and E-beam oxide on the (100) oriented n-type silicon wafers, respectively and they were directly bonded with another silicon wafer after hydrophilization using solutions of three types of $HNO_3$, $H_{2}SO_{4}$ and $NH_{4}OH$. Changes of average surface roughness after hydrophilizations of the single crystalline silicon wafer, thermal oxide and E-beam evaporated silicon oxide were studied using atomic force microscope. Bonding interfaces of the bonded pairs were inspected using scanning electron microscope. Void and non-contact area of the bonded pairs were also inspected using infrared transmission microscope.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.1
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• pp.22-26
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• 2014

$(Ba_{0.85}Ca_{0.15})(Ti_{0.9}Zr_{0.1})O_3$ + 0.04 wt% $CeO_2$ lead-free ceramics were prepared by conventional oxide-mixed method and the effect of sintering temperature on microstructure, dielectric and piezoelectric properties were investigated. Improved piezoelectric properties have been observed at $1,400^{\circ}C$ sintering temperature which show the optimal electrical properties, $k_p{\sim}0.412$, $d_{33}{\sim}316pC/N$, $Q_m{\sim}144$, ${\varepsilon}_r{\sim}3,345$ and $T_c{\sim}85^{\circ}C$. These results show that the sintering temperature plays an important role in piezoelectric properties.