• Design & Manufacturing
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• v.14 no.1
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• pp.1-7
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• 2020

In this study, the variation of the shrinkage in the thickness direction of the molded parts according to the gate size of the polymer core fabricated through the 3D printer using the SLS method was studied. The polymer cores are laser sintered and the powder material is nylon base PA2200. The polymer cores have lower heat transfer rate and rigidity than the metal core due to the characteristics of the material. Therefore, the injection molding test conditions are set to minimize the deformation of the core during the injection process. The resin used in the injection molding test is a PP material. The packing condition was set to 80, 90 and 100% of the maximum injection pressure for each gate size. The runner diameter used was ∅3mm, and the gates were fabricated in semicircle shapes with cross sections 1, 2, and 3 ㎟, respectively. Thickness measurement was performed for 10 points at 2.5 mm intervals from the point 2.5 mm away from the gate, and the shrinkage to thickness was measured for each point. The shrinkage rate according to the gate size tends to decrease as the cross-sectional area decreases as the maximum injection pressure increases. The average thickness shrinkage rate was close to 0% when the packing pressure was 90% for the gate area of 1mm2. When the holding pressure was set to 100%, the shrinkage was found to decrease by 3% from the standard dimension due to the over-packing phenomenon. Therefore, the smaller the gate, the more closely the molded dimensions can be molded due to the high pressure generation. It was confirmed that precise packing process control is necessary because over-packing phenomenon may occur.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.23-34
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• 1992

In order to fabricate magnetoresistive sensor, Fe-Ni and Co-Ni alleys were evaporated on the slide glass and the silicon wafers. Saturation magnetic induction($B_{s}$), coercive field strength($H_{c}$) and magnetoresistance were measured for fabricated samples. The evaporated Fe-Ni thin films show that the saturation magnetic induction was 0.65 T, and coercive field strength was 0.379 A/cm, and this value was changed to 0.370 A/cm(//), 0.390 A/cm(${\bot}$), respectively after magnetic annealing. For the measurement of coercive field strength, magnetizing frequency of 1 kHz was used. For the fabricated sensor element, the change of magnetoresistance (${\Delta}R/R$) was excessively unstable due to oxidation in the process of fabrication. The evaporated Co-Ni alloy thin films show that saturation magnetic induction was 0.66 T, and coercive field strengthes were 5.895 A/cm(//), 5.898 A/cm(${\bot}$), respectively, after magnetic annelaing. The change of magnetoresistance(${\Delta}R/R$) was $3.6{\sim}3.7%$ of which value was excessively stable to room temperature. Fe-Ni thin film could have many problems due to large affinity in the process of fabrication of magnetoresistance sensor, but Co-Ni thin film could be a suitable material for fabrication of magnetoresistance sensor, because of its small affinity and definite magnetoresistance effects.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.987-997
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• 2015

Schisandra chinensis (Sc), a species of the family Schisandraceae used fruits as medicinal herbs. In the study, we performed to determine a comparison of antioxidant activity from Sc water extracts depending on stir-frying and stir-frying with liquids by 30% ethanol pretreatments. The contents of polyphenol and flavonoid, DPPH radical scavenging, ABTS radical scavenging and reducing power activity were measured to evaluate the antioxidant activity. Total polyphenol and flavonoid contents of Sc extracts were increased in stir-frying and 30% ethanol stir-frying pretreatments compared to a control. In particular, contents of stir-frying pretreatments Sc were highest increased at $220^{\circ}C$ treatments. The DPPH radical scavenging activity were highest increased in stir-frying pretreatments at $220^{\circ}C$. And result that measurement of the ABTS radical scavenging, it showed higher activity in 30% ethanol stir-frying pretreatments at $180^{\circ}C$ and $220^{\circ}C$. But Sc in the $140^{\circ}C$ showed higher activity in stir-frying pretreatments. In the reducing power activity, stir-frying pretreatments increased higher than 30% ethanol stir-frying pretreatments at $220^{\circ}C$. As in results, antioxidant activity of Sc water extracts in stir-frying and stir-frying with liquids process increased higher than a control, and it was most effectively in stir-frying pretreatments at $220^{\circ}C$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.2
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• pp.90-103
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• 2005

Objective: This study was carried out to assess the status of working environments, to improve the working environments, and to be helpful to prevent occupational disease. Methods: The authors measured the noise level, concentration of dust, heavy metals, organic solvents, and other chemicals at 95 industries (22 working processes) by type of working process in manufacturing industry of parts and accessories for motor vehicles and its engines from January to December 2003. Samples were measured and analyzed by regulations of Korea Ministry of Labor, manuals of National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA). Results: Results are as follows. 1. Major processes exceeding mean noise levels provided the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) were shakeout [97.5 dB(A)]. shot-blast [94.2 dB(A)], pressing [92.9 dB(A)], crushing [91.2 dB(A)], and cleaning [90.6 dB(A)]. 2. Mean concentrations of dusts were not exceeded to the TLV. But concentration on some points of processes as like welding (6.50 mg/m3), foundry (5.24 mg/m3) were exceeded. 3. Mean concentrations of heavy metals were not exceeded to the TLV. 4. Mean concentrations of organic solvents and chemicals were not exceeded to the TLV. 5. Improving rate for working environment were significantly higher in industries with health manager than without (p<0.05), and by increasing the year of working environmental measurement (p<0.01). Conclusions: The results suggest that working processes of exceeding to the TLV will be needed rapid improvement of the working environment, and also the others will be needed positive management of the working environment. Health managers must be recommended to employ in the workplace, and further studies for relationship between working environment and health effects for the workers must be carried out.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.49-54
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• 2003

We have investigated the effects of hydrogen annealing on the physical and electrical properties of $SrBi_{2}Ta_{2}O_9(SBT)$ thin films in the Pt/SBT/Si (MFS) structure and Pt/SBT/Pt (MFM) one, respectively. The microstructure and electrical characteristics of the SBT films were deteriorated after hydrogen annealing due to the damage of the SBT films during the annealing process. To investigate the reason of the degradation of the SBT films in this work, in particular, the effect of the Pt top electrodes, SBT thin films deposited on Si, Pt, respectively, were annealed with the same process conditions. From the XRD, XPS, P-V, and C-V data, it was seen that the SBT itself was degraded after $H_2$ annealing even without the Pt top electrodes. In addition, the degradation of the SBT films after $H_2$ annealing was accelerated by the catalytic reaction of the Pt top electrodes which is so-called hydrogen degradation. To prevent this phenomenon, we proposed the alternative top electrode material, i.e. Ir, and the electrical properties of the SBT thin films were examined in the $Ir/IrO_2/SBT/IrO_2$ structures before and after the H$_2$ annealing and recovery heat-treatment processes. From the results of the P-V measurement, it could be concluded that Ir is one of the promising candidate as the electrode material for degradation resistance in the MFM structure using SBT thin films.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.10
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• pp.687-698
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• 2001

This paper presents a three dimensional stacked pad area away (PAA) package configuration as an implementation method of radio frequency (RF) circuits. 224MHz RF circuits of intelligence traffic system(ITS) were constructed with the stacked PAA RF pakage configuration. In the process of manufacturing the stacked PAA RF pakage, RF circuits were partitioned to subareas following their function and operating frequency. Each area of circuits separated to each subunits. The operating characteristics of RF PAA package module and the electrical properties of each subunits were examined. The measurement of electrical parameters for solder balls which were interconnects for stacked PAA RF packages showed that the parasitic capacitance and inductance were 30fF and 120pH, respectively, which might be negligible in PAA RF packaging system. HP 4396B network/spectrum analyzer revealed that the amplification gain of a receiver and transmitter at 224 MHz was 22dB and 27dB, respectively. The gain was 3dB lower than designed values. The difference was probably generated from fabrication process of the circuits by employing commercial standard

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.10
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• pp.1575-1580
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• 2018

Objective: This study was conducted to estimate the genetic parameters and breeding values of breast meat related traits of Pekin ducks. Selection response was also determined by using ultrasound breast muscle thickness (BMT) measurements in combination with bosom breadth (BB) and keel length (KL) values. Methods: The traits analyzed were breast meat weight (BMW), body weight (BW), breast meat percentage (BMP) and the three parameters of breast meat (BB, KL, and BMT). These measurements were derived from studying 15,781 Pekin ducks selected from 10 generations based on breast meat weight. Genetic parameters and breeding value were estimated for the analysis of the breeding process. Results: Estimated heritability of BMW and BMP were moderate (0.23 and 0.16, respectively), and heritability of BW was high (0.48). Other traits such as BB, KL, and BMT indicated moderate heritability ranging between 0.11 and 0.28. Significant phenotypic correlations of BMW with BW and BMP were discovered (p<0.05), and genetic correlations of BMW with BW and BMP were positive and high (0.83 and 0.66, respectively). It was noted that BMW had positive correlations with all the other traits. Generational average estimated breeding values of all traits increased substantially over the course of selection, which demonstrated that the ducks responded efficiently to increased breast meat yield after 10 generations of breeding. Conclusion: The results indicated that duck BMW had the potential to be increased through genetic selection with positive effects on BW and BMP. The ultrasound BMT, in combination with the measurement of BB and KL, is shown to be essential and effective in the process of high breast meat yield duck breeding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.771-776
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• 2017

The cover glass of mobile displays and photovoltaic cells needs a functional coating, such as an anti-reflection and self-cleaning coating. Numerous studies have been conducted on the engineering application of biomimetic functional surfaces, such as moth eye and lotus leaf Anti-reflection coantings of silica nanoparticles could enhance the light transmittance. $TiO_2$ photocatalyst coatings have been applied to self-cleaning functional films. In this study, transparent hydrophobic anti-reflective coatings consisting of thin layers of $SiO_2/TiO_2$ nanoparticles were fabricated on a slide glass substrate by the sol-gel process and dip-coating process. The dependence of the surface morphology of the functional coatings was investigated by the atomic force microscopy (AFM), contact angle measurement, and UV-visible spectroscopy. It was found that the coating of $TiO_2$ nanoparticles exhibited a high average transmittance comparable to that of the bare slide glass substrate in the visible light range. The bi-layered functional coating of 7 nm $SiO_2$/7nm $TiO_2$ nanoparticles exhibits a transparent hydrophobic surface with a contact angle of $110^{\circ}$ and an improvement of the average transmittance of 2.3% compared to the bare slide glass substrate in the visible light range.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.355-361
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• 2006

Artificially crushed sands occupy approximately 30 percent of the total consumption in South Korea. The demand for the crushed sands is expected to rise in the future. Most manufacturers use granitic rocks to produce the crushed sands. During the manufacturing process, fine fractions (i.e., sludges or particles smaller than 63 microns) are removed through the process of flocculation. The fine fraction occupies about 15% of the total weight. The sludges are comprised of quartz, feldspars, calcite, and various kinds of clay minerals. Non-clay minerals occupy more than 75 percent of the sluges weight, according to the XRD semi-quantification measurement. Micas, kaolinites, chlorite, vermiculite, and smectites occur as minor constituents. The sludges from Jurassic granites contain more kaolinites and $14{\AA}$-types than those from the Cretaceous ones. The chemical analysis clearly shows the difference between the parent rocks and the sludges in chemical compositions. Much of colored components in the sludges was accumulated as the weathering products. Particle size analysis results show that the sludges can be categorized as silt loam in a sand-silt-clay triangular diagram. This result was for her confirmed by the hydraulic conductivity data. In South Korea, the sludges remained after crushed sand production are classified as an industrial waste because of their impermeability, and which is caused by their high silt and clay fractions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.111-121
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• 2016

In this study, measurements were conducted by image processing to do an in-depth evaluation of strain of rebar in a uniaxial tension test. The distribution of strain and the necking region were evaluated. The image processing is used to analyze the color information of a colored image, so that the parts consistent with desired targets can be distinguished from the other parts. After this process, the image was converted to a binary one. Centroids of each target region are obtained in the binary images. After repeating such process on the images from starting point to the finishing point of the test, elongation between targets is calculated based on the centroid of each target. The tensile test were conducted on grade 60 #7(D22) and #9(D29) rebars fabricated in accordance with ASTM A615 standards. Strain results from image processing were compared to the results from a conventional strain gauge, in order to see the validity of the image processing. With the image processing, the measuring was possible in not only the initial elastic region but also the necking region of more than 0.5(50%) strain. The image processing can remove the measuring limits as long as the targets can be video recorded. It also can measure strain at various spots because the targets can easily be attached and detached. Thus it is concluded that the image processing helps overcome limits in strain measuring and will be used in various ways.