• Journal of computational fluids engineering
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• v.19 no.4
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• pp.37-44
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• 2014

A detailed satellite panel thermal model composed of more than thousands nodes can not be directly integrated into a spacecraft thermal model due to its node size and the limitation of commercial satellite thermal analysis programs. For the integration of the panel into the satellite thermal model, a reduced thermal model having proper accuracy is required. A thermal model reduction method was developed and validated by using a geostationary satellite panel. The temperature differences of main components between the detailed and the reduced thermal model were less than $1^{\circ}C$ in steady state analysis. Also, the dynamic responses of the detailed and the reduced thermal model show very similar trends. Thus, the developed reduction method can be applicable to actual satellite thermal design and analysis with resonable accuracy and convenience.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.8-14
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• 2007

The geometry in the weight reduction design is very required to be started from the conceptual design with low cost, high performance and quality. In this point, a topological shape fur optimization concerned with conceptual design of structure is important. The method used in this paper combines three optimization techniques, where the shape and physical dimensions of the structure and material distribution are hierachically optimized, with the maximum rigidity of structure and lightweight. As the applications, the technology of weight reduction design is applied on designs of aluminum control arm and inner panel of hood.

• Journal of Powder Materials
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• v.10 no.6
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• pp.436-442
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• 2003

The magnetic Nd-Fe-B powders were prepared by a thermochemical method, consisting of the processes of spray-drying, debinding, milling, H$_2$-reduction, Ca-reduction, and washing. The optimum process conditions were studied by microstructural and thermal analysis. The resultant Nd-Fe-B powder was spherical with the size of 1 ${\mu}{\textrm}{m}$. Effects of the process parameters of each step on the microstructure of the powders were investigated, and their magnetic properties were evaluated.

• Journal of Powder Materials
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• v.19 no.5
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• pp.356-361
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• 2012

The ultra-fine and less agglomerated titanium carbonitride particles were successfully synthesized by magnesiothermic reduction with low feeding rate of $TiCl_4+1/4C_2Cl_4$ solution. The sub-stoichiometric titanium carbide ($TiC_{0.5{\sim}0.6}$) particles were produced by reduction of chlorine component by liquid magnesium at $800^{\circ}C$ of gaseous $TiCl_4+1/4C_2Cl_4$ and the heat treatments in vacuum were performed for 5 hours to remove the residual magnesium and magnesium chloride mixed with produced $TiC_{{\sim}0.5}$. The final $TiC_{{\sim}0.5}N_{0{\sim}0.5}$ particle with near 100 nm in mean size and high specific surface area of $65m^2/g$ was obtained by nitrification under nitrogen gas at $1,150^{\circ}C$ for 2 hrs.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.1
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• pp.11-28
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• 2009

Intelligent investment in setup cost reduction and process reliability improvement is crucial to an emerging integrated lean six sigma practice today. This study examines a cost-minimizing problem of jointly determining production lot size, setup cost reduction, and process reliability improvement decisions for a manufacturer with an imperfect production process. We develop models for previously untapped discrete shipping in a supply chain context as well as continuous shipping and solve them optimally using differential calculus and nonlinear programming. We also conduct analytic and numerical sensitivity analyses to provide various important managerial insights into practices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.415-423
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• 1996

Hydrogen reduction technique was used to form the nickel layer onto alumina powders in nickel sulfate solutions. The reduction rate and precipitation states of nickel ions were investigated at various experimental conditions such as hydrogen pressure, temperature, $PdCl_{2}$ addition, particle size, and so on. Uniformly nickel coated alumina composite powders were obtained at such condition as reduction temperature of $165^{\circ}C$, hydrogen pressure of 300 psi, and $PdCl_{2}$ amount of $2\;mg/\ell$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.310-317
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• 2006

Currently most practical vibration and structural problems in automotive suspensions require the use of the finite element method to obtain their structural responses. When the finite element model has a very large number of degrees of freedom the harmonic and dynamic analyses are computationally too expensive to repeat within a feasible design process time. To alleviate the computational difficulty, this paper presents a moment-matching based model order reduction (MOR) which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary simulations with the reduced-size models. The moment-matching model reduction via the Arnoldi process is performed directly to ANSYS finite element models by software mor4ansys. Among automotive suspension components, a knuckle is taken as an example to demonstrate the advantages of this approach for vibration simulation. The frequency and transient dynamic responses by the MOR are compared with those by the mode superposition method.

• Journal of the Korea Society for Simulation
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• v.10 no.2
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• pp.61-74
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• 2001

The reliability evaluation of the large scale network becomes very complicate according to the growing size of network. Moreover if the reliability is not constant but follows probability distribution function, it is almost impossible to compute them in theory. This paper studies the network evaluation methods in order to overcome such difficulties. For this an efficient path set algorithm which seeks the path set connecting the start and terminal nodes efficiently is developed. Also, various variance reduction techniques are applied to compute the system reliability to enhance the simulation performance. As a numerical example, a large scale network is given. The comparisons of the path set algorithm and the variance reduction techniques are discussed.

• Journal of Powder Materials
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• v.26 no.4
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• pp.340-344
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• 2019

Due to the rapid development of electricity, electronics, information communication, and biotechnology in recent years, studies are actively being conducted on nanopowders as it is required not only for high strengthening but also for high-function powder with electric, magnetic, and optical properties. Nonetheless, studies on nickel nanopowders are rare. In this study of the synthesis of nickel nanoparticles from $LiNiO_2$ (LNO), which is a cathode active material, we have synthesized the nanosized nickel powder by the liquid reduction process of $NiSO_4$ obtained through the leaching and purification of LNO. Moreover, we have studied the reduction reaction rate according to the temperature change of liquid phase reduction and the change of particle size as a function of NaOH addition amount using hydrazine monohydrate ($N_2H_4{\cdot}H_2O$) and NaOH.

• Food Science and Industry
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• v.49 no.2
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• pp.18-24
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• 2016

Sodium chloride (NaCl) is a very important as one of major food ingredients in food industries. Recently, as the potential risk of adult diseases such as hypertension by overingestion of sodium, health authorities of many countries are executing policies for the reduction of sodium to suppress the overingestion of sodium by intake of NaCl. As general ways, the replacement of NaCl with either alternative salts, such as solar salts and minerals, for examples calcium, magnesium, potassium, lactic acid, and so on, and the addition of flavor enhancers were used to reduce the contents of sodium in foods. Recently, controls of particle size of sodium chloride or release point are emerging as new salt-manufacturing technologies for the sodium reduction. Upon reducing NaCl in foods it is important to develop practically adaptable technologies on the basis of the consideration of the unique functions of NaCl in foods, in particular effects on rheological characters, function as a humectant, shorten shelf life time, and so on.