• Structural Engineering and Mechanics
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• 제50권5호
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• pp.575-588
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• 2014

Gel materials have recently gained more attention due to its unique capability of large and reversible volumetric changes. This study explores the possibility of mimicking the pattern formation of certain natural fruits during their growing process and leaves during drying processes through the swelling and de-swelling of gel materials. This will hopefully provide certain technical explanations on the morphology of fruits and plants. We adopt the inhomogeneous field gel theory to predict the deformation configurations of gel structures to describe the morphology of natural fruits and plants. The growing processes of apple and capsicum are simulated by imposing appropriate boundary conditions and field loading via varying the chemical potential from their immature to mature stages. The drying processes of three types of leaves with different vein structures are also investigated. The simulations lead to promising results and demonstrate that pattern formation of fruits and plants may be described from mechanical perspective by the behavior of gel materials based on the inhomogeneous field theory.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.434-435
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• 2009

The crystalline silicon solar cell where the solar cell market grows rapidly is occupying of about 85% or more. high-efficiency and low cost endeavors many crystalline silicon solar cells. the fabrication processes of high-efficiency crystalline silicon solar cells necessitate complicated fabrication processes and Ti/Pd/Ag contact, however, this contact formation processed by expensive materials. Ni/Cu contact formation is good alternative. in this paper, according to temperature Ni silicide makes, produced Ni/Cu contact solar cell and measured conversion efficiency.

• 한국연소학회지
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• 제4권2호
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• pp.51-62
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• 1999

NOx formation in turbulent flames is strongly coupled with temperature, superequilibrium concentration of O radical, and residence time. This implies that in order to accurately predict NO level, it is necessary to develop sophisticated models able to account for the complex turbulent combustion processes including turbulence/chemistry interaction and radiative heat transfer. The present study numerically investigates the turbulent nonpremixed hydrogen jet flames using the laminar flamelet model. Flamelet library is constructed by solving the modified Peters equations and the turbulent combustion model is extended to nonadiabatic flame by introducing the enthalpy defect. The effects of turbulent fluctuation are taken into account by the presumed joint PDFs for mixture fraction, scalar dissipation rate, and enthalpy defect. The predictive capability of the present model has been validated against the detailed experimental data. Effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.93-104
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• 1999

NOx formation in turbulent flames is strongly coupled with temperature, superequilibrium concentration of O radical, and residence time. This implies that in order to accurately predict NO level, it is necessary to develop sophisticated models able to account for the complex turbulent combustion processes including turbulence/chemistry interaction and radiative heat transfer. The present study numerically investigates the turbulent nonpremixed hydrogen jet flames using the laminar flamelet model. Flamelet library is constructed by solving the modified Peters equations and the turbulent combustion model is extended to nonadiabatic flame by introducing the enthalpy defect. The effects of turbulent fluctuation are taken into account by the presumed joint PDFs for mixture fraction, scalar dissipation rate, and enthalpy defect. The predictive capability of the present model has been validated against the detailed experimental data. Effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• 천문학회지
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• 제29권spc1호
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• pp.201-204
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• 1996

Magnetic fields are thought to playa role in a wide variety of important astrophysical processes, from angular momentum transport and jet formation in accretion disks to corona formation in stars. Unfortunately, the dynamics of magnetic fields in astrophysical plasmas are extremely complicated, and the success of current theoretical models and computer simulations seems to be inversely correlated with the amount of observational detail available to us. Here I will discuss some of the more striking conflicts between numerical simulations and observations, and present an explanation for them based on an important dynamical process which is not adequately modeled in current numerical simulations. These processes will lead to the formation of flux tubes in stars and accretion disks, in accordance with observations. I will discuss some of the implications of flux tube formation for stellar and accretion disk dynamos.

• Ocean and Polar Research
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• 제26권3호
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• pp.515-521
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• 2004

The processes of formation and dissociation of gas hydrates were investigated by monitoring pressure and temperature variations in a pressure cell in order to understand the kinetic behavior of gas hydrate and the controlling factors fur the phase transition of gas hydrate below freezing. Gas hydrates were made kom guest gases ($CH_4,\;CO_2$, and their mixed-gas) and fine ice powder. We found that formation and dissociation speeds of gas hydrates were not controlled by temperature and pressure conditions alone. The results of this study suggested that pressure levels at the formation of mixed-gas hydrate determine the transient equilibrium pressure itself.

• 한국정밀공학회지
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• 제19권9호
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• pp.90-97
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• 2002

Ceramics are being increasingly used in industry due to their outstanding physical and chemical properties. But these materials are difficult to machine by traditional machining processes, because they are hard and brittle. Recently, as one of various alternative processes, laser-beam machining is widely used in the cutting of ceramics. Although the use of lasers presents a number of advantages over other methods, one of the problems associated with this process is the uncertain formation of cracks that result from the thermal stresses. This paper presents a Bayesian probabilistic modeling of crack formation over thin alumina plates during laser cutting.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.158-162
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• 1996

The steady-state emission and fluorescence lifetimes of 1,3-dipyrenylpropane were measured in silicate sol-gel and xerogel matrices. In sol solution, the fluorescence emission spectra of monomer and excimer resemble those in hydrocarbon solvents. In gel and xerogel condition, however, the fluorescence spectra exhibit significant change, largely confirming the intramolecular motions in gel pores are influenced by microviscosity. The rate constants for intramolecular excimer formation were obtained from the measured fluorescence lifetimes and the rate processes for excimer forming in silicate sol-gel are described by a simple kinetic scheme.

• 상하수도학회지
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• 제21권4호
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• pp.395-407
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• 2007

Disinfection by-products(DBPs) are formed through the reaction between chlorine and natural organic matter(NOM) in water treatment. For reducing the formation of chlorinated DBPs in the drinking water treatment, there is a need to evaluate the behavior of NOM fractions and the occurrence of DBPs for each fraction. Among the six fractions of NOM, the removal of HPOA and HPIN got accomplished through coagulation and sedimentation processes. Advanced water treatment processes were found to be most significant to remove the HPOA and HPON. It was found that HPOA made the most THMFP level than any other fractions and HPIA and HPOA formed higher HAAFP. The fraction of NOM with MW less than 1k Da was 32.5~54.3% in intake raw water. Mostly the organic matter with MW more than 1k Da was removed through coagulation and sedimentation in the drinking water treatment processes. In case of advanced water treatment processes, the organic matter with MW 1k~100k Da decreased by means of ozone oxidation for high molecular weight substances. As the result low molecular organic matter increased. In the BAC and GAC processes, the organic matter with MW less than 100k Da decreased.

• 대한화장품학회지
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• 제25권2호
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• pp.27-34
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• 1999

Biochemical, enzymatic, immunological, and morphological evidences on ceramide and other lipids lamellae formation, assembly of component proteins of CE and expression and distribution of TGases provided better understanding of CE formation. Pathophysiology of some of the genetic disease is beginning to be clarified. Hope we can utilize the information gained in understanding CE formation would expedite the development of patient treatment processes.