• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.95-102
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• 2002

With recent trends leaning towards product miniaturization, the advent of new material and speedy delivery times, old style conventional trial-and-error methods have been only serving to weaken corporate competitiveness. Reliant on tiny increments of time-consuming experience, this antiquated approach begets a delayed delivery of product development, cost loss and quality depreciation. To solve such problems, the Dedicated Injection Molding CAPA (Computer Aided Plastics Application) performs a preliminary examination on problems rising from every stage of creation - from appropriate material selection and mold design to mass production - through a computer system. Thus, it determines the optimum design variables and process conditions while diagnosing and solving defective molds.

• Transactions of Materials Processing
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• v.16 no.7
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• pp.530-537
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• 2007

This paper is concerned with the analysis of plastic deformation of bimetal co-extrusion process. Two sets of material combination have been adopted for analysis, i.e. combinations of Cu/Al and Fe/Al. In the first set of material combination, the selected materials are AA 1100 aluminum alloy as hard material and CDA 110 as soft one. This type of material selection is to examine the effect of hard core and soft sleeve and vice versa on the deformation pattern in terms of plastic zone and velocity discontinuity along the contact surface between construction materials. Four different cases of co-extrusion process in terms of material combination and interference bonding were simulated to investigate the effect of material arrangement between core and sleeve, and of bonding on the plastic zones and velocity discontinuity. In the other set of material combination, model materials used as core and sleeve were AA 1100 and AISI 1010, which are relatively soft and hard, respectively. Process parameters except diameter ratio of core to sleeve material such as semi-die angle, reduction in area in global sense and die comer radius have been set constant throughout the simulation to concentrate our effort on the analysis of influence of diameter ratio on deformation behavior such as deformation zone, surface expansion, exit velocity discontinuity between composite materials, and extrusion forces.

• Journal of computational fluids engineering
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• v.18 no.1
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• pp.58-62
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• 2013

Personal Rapid Transit (PRT) is the emerging personal transport vehicle operating on the loop automatically. The PRT system utilize the electrical power from super capacity or battery, it is important to manage the power or energy. In this regards, the management of high temperature occurred by the operation of system is significantly important to prevent from serious damage of component. In this study, we studied the adequate shape of underbody which can reduce the heat accumulation by pickup coil and condenser using natural air cooling. We suggested the additional air pathway, air inlet and flow separator to decrease the temperature of the heat source components. It was found that suggested system can decrease the temperature of PRT under body by 16% during the static mode and by 10% during the running mode at 30km/h. It is expected that the findings of this study will feed into final design of newly built Korean PRT vehicle.

• Food Science of Animal Resources
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• v.41 no.2
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• pp.324-334
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• 2021

This study aimed at determining the genetic and virulence characteristics of the Listeria monocytogenes from smoked ducks. L. monocytogenes was isolated by plating, and the isolated colonies were identified by PCR. All the obtained seven L. monocytogenes isolates possessed the virulence genes (inlA, inlB, plcB, and hlyA) and a 385 bp actA amplicon. The L. monocytogenes isolates (SMFM2018 SD 1-1, SMFM 2018 SD 4-1, SMFM 2018 SD 4-2, SMFM 2018 SD 5-2, SMFM 2018 SD 5-3, SMFM 2018 SD 6-2, and SMFM 2018 SD 7-1) were inoculated in tryptic soy broth (TSB) containing 0.6% yeast extract at 60℃, followed by cell counting on tryptic soy agar (TSA) containing 0.6% yeast extract at 0, 2, 5, 8, and 10 min. We identified five heat resistant isolates compared to the standard strain (L. monocytogenes ATCC13932), among which three exhibited the serotype 1/2b and D-values of 5.41, 6.48, and 6.71, respectively at 60℃. The optical densities of the cultures were regulated to a 0.5 McFarland standard to assess resistance against nine antibiotics after an incubation at 30℃ for 24 h. All isolates were penicillin G resistant, possessing the virulence genes (inlA, inlB, plcB, and hlyA) and the 385-bp actA amplicon, moreover, three isolates showed clindamycin resistance. In conclusion, this study allowed us to characterize L. monocytogenes isolates from smoked ducks, exhibiting clindamycin and penicillin G resistance, along with the 385-bp actA amplicon, representing higher invasion efficiency than the 268-bp actA, and the higher heat resistance serotype 1/2b.

• Journal of Ginseng Research
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• v.35 no.2
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• pp.243-249
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• 2011

Korean red ginseng (KRG), the steamed root of Panax ginseng Meyer, has a variety of biological properties, including anti-inflammatory, antioxidant and anticancer effects. Aflatoxin $B_1$ ($AFB_1$) produced by the Aspergillus spp. causes acute hepatotoxicity by lipid peroxidation and oxidative DNA damage, and induces liver carcinoma in humans and laboratory animals. This study was performed to examine the protective effects of KRG against hepatotoxicity induced by $AFB_1$ using liver-specific serum marker analysis, histopathology, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. In addition, to elucidate the possible mechanism of hepatoprotective effects, superoxide dismutase, catalase, glutathione peroxidase, and malondialdehyde were analyzed. Rats were treated with 250 mg/kg of KRG (KRG group) or saline ($AFB_1$ group) for 4 weeks and then received 150 ${\mu}g/kg$ of $AFB_1$ intraperitoneally for 3 days. Rats were sacrificed at 12 h, 24 h, 48 h, 72 h, or 1 wk after $AFB_1$ treatment. In the KRG pre-treatment group, serum alanine aminotransferase, aspartate aminotransferase, and malondialdehyde levels were low, but superoxide dismutase, catalase, and glutathione peroxidase activities were high as compared to the $AFB_1$ alone group. Histopathologically, $AFB_1$ treatment induced necrosis and apoptosis in hepatocytes, and led to inflammatory cells infiltration in the liver. KRG pre-treatment ameliorated these changes. These results indicate that KRG may have protective effects against hepatotoxicity induced by $AFB_1$ that involve the antioxidant properties of KRG.

• Geomechanics and Engineering
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• v.20 no.4
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• pp.287-297
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• 2020

This paper investigates the stability of a three-dimensional (3D) wedge under the pseudo-static action of an earthquake based on the nonlinear Barton-Bandis (B-B) failure criterion. The influences of the mechanical parameters of the discontinuity surface, the geometric parameters of the wedge and the pseudo-static parameters of the earthquake on the stability of the wedge are analyzed, as well as the sensitivity of these parameters. Moreover, a stereographic projection is used to evaluate the influence of pseudo-static direction on instability mode. The parametric analyses show that the stability coefficient and the instability mode of the wedge depend on the mechanical parameter of the rock mass, the geometric form of the wedge and the pseudo-static state of the earthquake. The friction angle of the rock φ_b, the roughness coefficient of the structure surface JRC and the two angles related to strikes of the joints θ₁ and θ₂ are sensitive to stability. Furthermore, the sensitivity of wedge height h, the compressive strength of the rock at the fracture surface JCS and the slope angle α to the stability are insignificant.

• ETRI Journal
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• v.26 no.4
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• pp.315-320
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• 2004

This paper proposes a 10-${\mu}m$ thick oxide layer structure that can be used as a substrate for RF circuits. The structure has been fabricated using an anodic reaction and complex oxidation, which is a combined process of low-temperature thermal oxidation (500 $^{\circ}C$ for 1 hr at $H_2O/O_2$) and a rapid thermal oxidation (RTO) process (1050 ${\circ}C$, for 1 min). The electrical characteristics of the oxidized porous silicon layer (OPSL) were almost the same as those of standard thermal silicon dioxide. The leakage current density through the OPSL of 10 ${\mu}m$ was about 10 to 50 $nA/cm^2$ in the range of 0 to 50 V. The average value of the breakdown field was about 3.9 MV/cm. From the X-ray photo-electron spectroscopy (XPS) analysis, surface and internal oxide films of OPSL prepared by a complex process were confirmed to be completely oxidized. The role of the RTO process was also important for the densification of the porous silicon layer (PSL) oxidized at a lower temperature. The measured working frequency of the coplanar waveguide (CPW) type short stub on an OPSL prepared by the complex oxidation process was 27.5 GHz, and the return loss was 4.2 dB, similar to that of the CPW-type short stub on an OPSL prepared at a temperature of 1050 $^{\circ}C$ (1 hr at $H_2O/O_2$). Also, the measured working frequency of the CPW-type open stub on an OPSL prepared by the complex oxidation process was 30.5 GHz, and the return was 15 dB at midband, similar to that of the CPW-type open stub on an OPSL prepared at a temperature of $1050^{\circ}C$ (1 hr at $H_2O/O_2$).

• Analytical Science and Technology
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• v.18 no.5
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• pp.381-385
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• 2005

The title compound, $\{H_2NCH_2CH_2NH_2CH_2CH_2\}\{Cu(H_2O)_6\}(SO_4)_2$, I, has been synthesized under solvo/hydrothermal conditions and their crystal structure analyzed by X-ray single crystallography. Compound I crystallizes in the monoclinic system, $P2_1/n$ space group with a = 6.852(1), b = 10.160(2), $c=11.893(1){\AA}$, ${\beta}=92.928(8)^{\circ}$, $V=826.9(2){\AA}^3$, Z = 2, $D_x=1.815g/cm^3$, $R_1=0.031$ and ${\omega}R_2=0.084$. The crystal structure of the piperazine templated Cu(II)-sulfate demonstrate zero-dimensional compound constituted by doubly protonated piperazine cations, hexahydrated copper cations and sulfate anions. The central Cu atom has a elongated octahedral coordination geometry. The crystal structure is stabilized by three-dimensional networks of the intermolecular $O_{water}-H{\cdots}O_{sulfate}$ and $N_{pip}-H{\cdots}O_{sulfate}$ hydrogen bonds between the water molecules and sulfate anions and protonated piperazine cations. Based on the results of thermal analysis, the thermal decomposition reaction of compound I was analyzed to have three distinctive stages.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.600-606
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• 2008

In closed-die hot forging, a billet is formed in dies such that the flow of metal from the die cavity is restricted. Some parts can be forged in a single set of dies, whilst others, due to shape complexity and material flow limitations, must be shaped in multi sets of dies. The purpose of a performing operation is to distribute the volume of the parts such that material flow in the finisher dies will be sound. This study focused on the design of preforms, flash thickness and land width by theoretical calculation and finite element analysis, to manufacture the super hot forging product, 70MC type piston crown used in marine engine. The optimal design of preforms by the finite element analysis and the design experiment achieves adequate metal distribution without any defects and guarantees the minimum forming load and fully filling of the cavity of the die for producing the large piston crown. The maximum loads obtained by finite element analysis are compared with the results of experiments. The loads of the analysis have good agreements with those of the experiment. Results obtained using DEFORM-2D enable the designer and manufacturer of super hot forging dies to be more efficient in this field.

• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.23-30
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• 2008

The objective of this study was to estimate the optimum scale of PLMTP (Public Livestock Manure Treatment Plant) for the efficient management of public sector by long-run cost function. An economic analysis was performed using the survey of 52 PLMTP records collected by Ministry of Environment in 2007. The main results obtained in this study can be summed up as follows. The optimum scale under given environmental conditions turned out to be $180{\sim}200m^3$/day which is almost $1.5{\sim}1.6$ times of the average scale of sample plants, $146m^3$/day. This gap between the optimum and current scale suggests that there remains the possibility of further expansion of scale.