• Transactions of Materials Processing
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• v.16 no.8
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• pp.575-581
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• 2007

The high dimensional accuracy of the cold forged part could be acquired by the accurate dimensional modification for the die, which is, the dimensional changes from the die through forged part to final part after heat treatment were considered. The experimental and FEM analysis are performed to investigate the dimensional changes from the die to final part on cold forged part, comparing with the machined gear. The dimension of forged part is compared with the die dimension at each stage, such as, machined die, cold forged part, and heat-treated-part. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the $DEFORM-3D^{TM}$. The analyzed residual stress of forged part is considered into the FE-analysis for heat treatment using the $DEFORM-HT^{TM}$. The effects of residual stress affected into the dimensional changes could be investigated by the FEA. Each residual stress of gears was measured practically by laser beam type measurement.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.225-234
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• 2000

The purpose of this study was to investigate the distribution and fluorescene intensity of vasoactive intestinal polypeptide(VIP) immunoreactive cells in rat trigeminal ganglion after inferior alveolar nerve axotomy. The animals were divided into normal and two experimental groups. The experimental animals were sacrificed at 14th and 28th day after inferior alveolar nerve axotomy. The trigeminal ganglion was removed and immersed in the 4% paraformaldehyde-0.2% picric acid in 0.1M phosphate buffer. Serial frozon sections about $16{\mu}m$ in thickness were cut with a cryostat. The immunofluorescence staining was performed. The rabbit anti-VIP(1 : 8,000) was used as primary antibody and fluorescene isothiocynate(FITC)-conjugated anti-rabbit IgG(1 : 80) as secondary antibody. The slides were observed under confocal laser scanning microscope. Three-dimensional images were constructed from 9 serial images(each $1{\mu}m$ in thickness) made by automatic optical sectioning. Unprocessed optical sections were obtained and stored on a optical disk. Color picture were printed by a video copy processor. The results were as follows; 1. The appearance of VIP immunoreactive cells in the mandibular part of trigeminal ganglion was 8.79${\pm}$1.99% in normal group and 39.16${\pm}$5.62% in 14 days, 16.25${\pm}$2.39% in 28 days after inferior alveolar nerve axotomy groups. 2. The relative fluorescence intensity of VIP immunoreactive cell bodies in the mandibular part of trigeminal ganglion was 134.40${\pm}$10.39 in normal group and 192.88${\pm}$14.06 in 14 days, 143.10${\pm}$5.02 in 28 days after nerve axotomy groups. Therefore, the relative fluorescence intensity of 14 days after nerve axotomy group was 43.3% higher than intensity of normal group. 3. In optical single section analysis of VIP immunoreactive cell bodies, white cell bodies(moderate fluorescence intensity) were the most abundant in normal and 28 days after nerve axotomy groups. Whereas, in 14 days after nerve axotomy group, red cell bodies(high fluorescence intensity) were the most abundant. 4. In optical serial section analysis of VIP immunoreactive cell bodies, red cell bodies(high fluorescence intensity) were observed in a part of the 9 sections of normal and 24 days after nerve axotomy groups. Whereas, red cell bodies were observed in all of the 9 sections of 14 days after nerve axotomy group. 5. The results indicates that number and fluorescence intensity of VIP immunoreactive cells were increased in the mandibular part of trigeminal ganglion following inferior alveolar nerve axotomy.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.23-27
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• 1999

After kaolin clay was compulsorily contaminated by Sr$^{2+}$ solution, the remediation characteristics by electrokinetic method were analyzed. Meanwhile, the numerical code for analysis of electrokinetic migration was developed for modelling of the soil remediation. Experimental results are as follows After 3 day remidiation under 40 voltage, the front part of experimental cell was almost decontaminated, but the behind part didn't almost be decontaminated. Accordingly, the total remediation ratio of Sr$^{2+}$ from cell soil was about 42.6 %. Also, the total Sr$^{2+}$ remediation ratio from cell soil was about 84.8 % after 6 days, and about 97.1 % after 7 days. Meanwhile, the values calculated by the developed code almost agreed with experimental values.ues.

• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.183-190
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• 2007

Injection molding is one of the most common operations in polymer processing. Good quality products are usually obtained and major post-processing treatment is not required. However, residual stresses which exist in plastic parts affect the final shape and mechanical properties after ejection. Residual stresses are caused by polymer melt flow, pressure distribution, non-uniform temperature field, and density distribution. Residual stresses are predicted in this study by numerical methods using commercially available softwares, $Hypermesh^{TM},\;Moldflow^{TM}\;and\;ABAQUS^{TM}$. Cavity filling, packing, and cooling stages are simulated to predict residual stress field right after ejection by assuming an isotropic elastic solid. Thermo-viscoelastic stress analysis is carried out to predict deformation and residual stress distribution after annealing of the part. Residual stresses are measured by the hole drilling method because the automotive part selected in this study has a complex shape. Residual stress distribution predicted by the thermal stress analysis is compared with the measurement results obtained by the hole drilling method. The molded specimen has residual stress distribution in tension, compression, and tension from the surface to the center of the part. Viscoelastic deformation of the part is predicted during annealing and the deformed geometry is compared with that measured by a three dimensional scanner. The viscoelastic stress analysis with a thermal cycle will enable us to predict long term behavior of the injection molded polymeric parts.

• Ocean and Polar Research
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• v.44 no.2
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• pp.127-137
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• 2022

This study examined the growth pattern and environmental factors affecting the growth of the halophyte, Suaeda japonica, which is prevalent on tidal flats in the west coast of Korea in order to calculate annual carbon production. Quantitative sampling was conducted every month for three years from 2018 to 2020 on salt marshes located on the southern coast of Ganghwa Island. In terms of annual density affected by the germination rate at first period, especially when air temperature for winter time was constantly below 0℃ for long periods of time, germination decreased and precipitation in summer also exerted an influence. In terms of annual growth with regard to length, the part below the ground grew rapidly in the beginning after budding, while the part above ground grew at a relatively steady rate at all times. With regard to biomass, the part below the ground also increased from April in a manner similar to length growth, but decreased drastically from September with leaves falling off and water loss occurring. The part above ground showed a rapid increase from the beginning of the rainy season. Size-frequency distribution revealed broader patterns after the rainy season as individual growth varied, but from September, it stopped at all year. High growth rates were recorded in the initial phase of growth after budding and growth was rapid, but growth declined in summer when biomass increased. The annual mean production based on growth rate was calculated at 352 gDWt/m²/yr, and the highest production was 519 gDWt/m²/yr in 2018, but it has decreased since 2019. Annual carbon production was at calculated 143.41 gC/m²/yr for Suaeda japonica in the vicinity of the southern coast of Ganghwa Island.

• Design & Manufacturing
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• v.6 no.2
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• pp.79-83
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• 2012

Inner part is used as an insulator in wire fuses. After injection molding, inner part has been showed flashes, filling defects and deformation. After production, operators have to cut off flashes, one by one. this process leads to continuous low productivity and loss of source materials. This study focuses on identifying the causes for flashes, filling defects, clamping force of injectors, mold adhesion, resin of liquidity and others, and on resolving those issues.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.109-112
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• 2005

Friction welding is welding method to use frictional heat of two material. A defect of friction welding is that create flash. The flash is part that must have cut after welding finished. But the welding part with flow gallery by friction welding can't cut flash. Therefore the welding part with flow gallery was designed with no effect in flow. In this research, decide the welding shape parameter of welding part with flow gallery and do friction welding analysis. In friction welding analysis, must input necessary S-S curve, friction coefficient by temperature change, upset pressure, RPM etc. According to analysis result, decided the optimal shape of welding part with no effect in flow.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.129-134
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• 2009

The dimension of forged part is different from that of die. Therefore, a more precise die dimension is necessarys to produce the precise part, considering the dimensional changes from forging die to final part. In this paper, both experimental and FEM analysis are performed to investigate the effect of several features including die dimension at each forging step and heat-treatment on final part accuracy in the closed-die upsetting. The dimension of forged part is checked at each stage as machined die, cold forged, and post-heat-treatment steps. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the DEFORM-$2D^{TM}$. The effect of residual stress after heat-treatment on forged part could be considered successfully by using DEFOAM-$HT^{TM}$.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1286-1288
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• 1996

An add/drop control chip for SDH transmission system has been designed in AT&T 0.5um CMOS ORCA FPGA. This device plays an important role in achieving self-healing ring operation which protects against failure. After this device receives each 24-ch AU-3 signals from the west, east, and add parts, it outputs each 24-ch switched signals through the control data of system control port. This device consists of eight sub-part such west/east transmitting part, west/east receiving part, add/drop control part, AIS control part, and CPU interface part. The designed device is capable to ring networks as well as linear networks.

• Journal of Korean Institute of Industrial Engineers
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• v.7 no.1
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• pp.13-20
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• 1981

Three inspection-ordering policies of a part with three types of lead times, i. e., expedited lead time, special lead time and regular lead time are considered. Policy I : The original part is replaced by a spare immediately after delivery, even if the original part is still operating. Policy II : The delivered spare is put into inventory until the original part failes. Policy III : The original part is inspected once again immediately after the delivery of the spare. If it is in a good state, the original part is used up to its mean degradation time, then replaced. If it is in a degradation state, the original part is replaced by a spare. A cost effectiveness for each policy is analyzed. Optimal inspection-ordering policy which maximizes a cost effectiveness is obtained. Time to degradation distribution and time to failure distribution are assumed to be Weibull and exponential, respectively. Variations of policies are observed with respect to variations of associated costs.