• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.25-34
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• 2011

In this paper, we investigate an inventory system where a single manufacturer purchases and processes raw materials in order to deliver finished goods to multiple retailers. Earlier study in this type of supply chain only consider a single raw material in order to produce finished goods, but we consider multi-raw materials in order to produce finished goods. Also, we develop an iterative solution procedure to find the order quantity for the finished goods and raw materials, and the number of shipments between manufacturer and retailers that minimizes the total cost per unit time of the raw materials ordering and holding, manufacture's setup and finished goods holding, the retailer's ordering and inventory holding. Numerical examples are presented to illustrate that jointly considering the total cost results in less total cost than that of considering them separately.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.116-125
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• 2014

In this paper, we investigate an inventory and production system in a three-layer supply chain system involving a single supplier, single manufacturer and multiple retailers. Earlier study in this type of supply chain only consider a single raw material in order to produce single item, but we consider raw materials in order to produce multiple items. It is assumed that the cycle time at each stage is an integer multiple of the adjacent downstream stage. We develop an iterative solution procedure to find the order quantity for the multiple items and raw materials that minimizes the supply chain-wide total cost per unit time of the supplier and manufacturer's raw materials ordering and holding, setup and finished items holding, the retailer's ordering and inventory holding. Numerical examples are presented to show that the proposed heuristic gives good performance.

• 대한한약학회:학술대회논문집
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• 2007.11a
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• pp.129-144
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• 2007

In order for stable demand-supply and regularity of distribution, "The regulations for management of demand-supply and distribution of medicinal herbs" were established on 1995. Therefore, the medicinal herbs of good quality have been controled to be distributed in the market. However, to be wide of the purpose, the standardized sound distribution system was caused due to the governmental control on demand-supply to protect domestic farmers who produce the material for medicinal herbs, which results in the over distribution of non-standardized or illegally imported medicinal herbs. In addition, because of the distribution of faulty or poor medicinal herbs, there are chances of affecting bad effects on public health. The standardized medicinal herbs cover 514 different kinds in total, of which 69 products are specified to be standardized in the oriental medicine product companies. Also, in order to protect farmers who produce the materials for medicinal herbs, the amount of imported materials are regulated in normal times. The 14 different materials for medicinal herbs, which are allowed to be imported to a certain amount only when the shortage of goods or sudden rise of prices is to happen, are frequently introduced into domestic market as food not as medical usage, and the origin of those illegally changes to home cropped one for the distribution in the market. In addition, the system of distribution are to be disordered and the condition for the distribution of medicinal herbs of good quality can not be made since they illegally changes the usage of the materials for medicinal herbs from their original one and can not be regulated by the domestic laws.

• Journal of Magnetics
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• v.9 no.4
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• pp.109-112
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• 2004

The HDDR (Hydrogenation-Disproportionation-Desorption-Recombination) process is a special method to produce anisotropic NdFeB powders for bonded magnet. The effect of the modified HDDR process on magnetic properties of $Nd_2Fe_{14}B$-based magnet with several composition $Nd_{11.2}Fe_{66.5-x}Co_{15.4}B_{6,8}Zr{0.1}Ga_x(x=0{\sim}1.0)$ and that of microelement Ga, disproportional temperature and annealing temperature on $_jH_c$, grain size were investigated in order to produce anisotropic powder with high magnetic properties. It was found that modified HDDR process is very effective to enhance magnetic properties and to fine grain size. The addition of Ga could change disproportionation character remarkably of the alloy and could improve magnetic properties of magnet powder. Increasing annealing temperature induces significant grain growth. And grain size produced by modified HDDR process is significantly smaller than those produced by conventional HDDR process.

• Journal of Powder Materials
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• v.12 no.3
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• pp.208-213
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• 2005

Aluminum matrix composites strengthened by the quasi-crystalline (QC) phase were developed in the present study. The icosahedral $Al_{65}Cu_{20}Fe_{15}$ phase was produced by gravity casting and subsequent heat treatment. The mechanical milling process was utilized in order to produce the Al/QC composite powders. The microstructures of the composite powders were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The composite powders were subsequently canned, degassed and extruded in order to produce the bulk composite extrusions with various volume fractions of QC. The microstructure and mechanical properties of the extrusions were examined by OM, SEM, Vickers hardness tests and compression tests. It was found that the microstructures of the Al/QC composites were uniform and the mechanical properties could be significantly improved by the addition of the QC phase.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.190-198
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• 2016

Application of fuel cell to produce renewable energy for commercial purpose is limited by the high cost of Pt based electrode materials. Development of inexpensive, high energetic electrode is the need of the hour to produce pollution free energy using bio-fuel through a fuel cell. Ni-Cu and Ni-CeO₂-Cu electrode materials, electro synthesized by pulse current have been developed. The surface morphology of the electrode materials is controlled by different deposition parameters in order to produce a high current from the electro-oxidation of the fuel, the ethanol. The developed materials are electrochemically characterized by Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiodynamic polarization tests. The results confirm that the high current is due to their enhanced catalytic properties viz. high exchange current density (i₀), low polarization resistance (R_p) and low impedance. It is worthwhile to mention here that the addition of CeO₂ to Ni-Cu has outperformed Pt as far as the high electro catalytic properties are concerned; the exchange current density is about eight times higher than the same on Pt surface. The morphology of the electrode surface examined by SEM and FESEM exhibits that the grains are narrow and sub spherical with 3D surface, containing vacancies in between the elongated grains. The fact has enhanced more surface area for electro oxidation of the fuel, giving rise to an increase in current. Presence of Ni, CeO₂, and Cu is confirmed by the XRD and EDXS. Fuel cell fabricated with Ni-CeO₂-Cu material electrode is expected to produce clean electrical energy at cheaper rates than conventional one, using bio fuel the derived from biomass.

• Archives of Metallurgy and Materials
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• v.64 no.2
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• pp.613-616
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• 2019

The objective of the present research is to develop the novel multi-compaction technology to produce hybrid structure in powder metallurgy (P/M) components using dissimilar Fe-based alloys. Two distinct powder alloys with different compositions were are used in this study: Fe-Cr-Mo-C pre-alloyed powder for high strength and Fe-Cu-C mixed powder for enhanced machinability and lower material cost. Initially, Fe-Cu-C was pre-compacted using a bar-shaped die with lower compaction pressure. The green compact of Fe-Cu-C alloy was inserted into a die residing a half of the die, and another half of the die was filled with the Fe-Cr-Mo-C powder. Then they subsequently underwent re-compaction with higher pressure. The final compact was sintered at 1120℃ for 60 min. In order to determine the mechanical behavior, transverse rupture strength (TRS) and Vickers hardness of sintered materials were measured and correlated with density variations. The microstructure was characterized using optical microscope and scanning electron microscope to investigate the interfacial characteristics between dissimilar P/M alloys.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.9-12
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• 2005

Recently, research on the morphing wing is an interesting issue to develop the capability of the wing such as improving the lift and reduction of drag during the operation of an aircraft by changing the wing shape from one configuration to another. A more efficient weight reduction of the wing using smart or morphing wing concept can be achieved in comparison with the conventional flaps. In this study, it is investigated the behaviors of the morphing wing using Macro Fiber Composite (MFC) actuators. Generally, MFC is the piezocomposite actuator with the rectangular PZT fiber and epoxy matrix, and uses the interdigitated electrode to produce more powerful actuation in the in-plane direction. Furthermore, it can produce the twisting actuation as compared with the traditional PZT actuators. In the formulation, the first-order shear deformation plate theory is used, and finite element method is adopted in the numerical analysis of the model. Results show the characteristics of the static behavior of the morphing wing according to the change of the actuation voltage.

• Composites Research
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• v.12 no.5
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• pp.23-30
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• 1999

Fiber reinforced composite materials are widely used in automotive industry to produce parts that are large, thin, lightweight, strong and stiff. It is very important to know a charge shape in order to have good products in the compression molding. In particular, the product such as a bumper beam is composed of the random and unidirectional fiber mats. The characteristics of flow fronts such as a bulging phenomenon for random mat and unidirectional fiber mat and slip parameters are studied numerically. And the effects of viscosity ratio and stack type on mold filling parameters are also discussed.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.506-515
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• 2008

Recently, it is exceedingly required to produce metal powders with tailored shape and phase altogether in order to fabricate high performance functional parts such as magnetic core or electro-magnetic noise suppressor for high frequency usage. Therefore, the collision phenomena of in-flight droplets against chamber wall or neighboring in-flight droplets each other is investigated by a computational method in order to get useful information about how to design the atomizing system and how to tailor process parameters not to make irregular-shaped powders during gas atomization process. As a results, smaller powders, lower melt temperature are known to be favorable for droplets not to collide against chamber wall. In additions, powders of narrower size distribution range, lower droplet generation rate, lower melt temperature, lower gas velocity are desirable to prevent droplet-collisions against neighboring in-flight droplets.