• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.151-162
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• 2017

The purpose of this study was to investigate the quality change of fresh-cut tumeric (Curcuma Longa Linne) according to packaging method during storage time. The fresh-cut tumeric were packaged in three different methods : degassing valve packaging (DVP), $CO_2$ gas absorber packaging (CAP) and micro-perforated packaging (MPP). After the samples were packaged, they were stored for 15 days at 4 and $23^{\circ}C$ respectively. The following parameters were observed to indicate the quality changes of the samples: weight loss, CIE $L^*a^*b^*$ colour difference, variation of gas composition inside the package, curcumin contents and changes in hardness of fresh-cut tumeric. DVP did not effectively release $CO_2$ gas to the outside. MPP was suitable to release $CO_2$ gas. However, MPP showed very fast browning and erosion, because a large amount of oxygen was introduced through the perforated hole on the film. CAP was most effective packaging method to inhibit browning, to prevent expansion of the packaging by $CO_2$ gas and to minimize weight loss of fresh-cut tumeric.

• Journal of dental hygiene science
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• v.17 no.4
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• pp.358-367
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• 2017

The purpose of this study was to evaluate the influence of water infiltration and flexural strength changes in dental porcelain with glazing treatment. The block specimens were prepared as experimental materials, using feldspar type commercial dental porcelain; then, these were fired at $940^{\circ}C$ for 1 minute. The fired specimens were polished with a dimension of $40{\times}5.5{\times}5mm$. The specimens were distributed to two experimental groups: with and without glazing treatment specimens (n=5), and they were immersed in a solution of pH 7 for 3, 7, and 20 days at $40^{\circ}C$ after fabrication. To evaluate the flexural strength changes with water infiltration treatment in specimens with and without glazing, the 3-point flexural test was performed, using a universal testing machine until failure occurred. Starting powder and fired specimens consisted of amorphous and leucite crystalline phase. The Vickers hardness of fired specimens was more than 1.6 times higher than that of the enamel of natural teeth. According to porosimeter results, the specimens without glazing treatment exhibited a porosity of about 14.7%, whereas the glazed specimens exhibited the lowest porosity at about 1.1%. The average flexural strength of glazed specimens was higher than the flexural strength of specimens without glazing treatment (p<0.05). The flexural strength of all specimens with and without glazing treatment deteriorated with accelerated aging in the solution. In addition, significant differences between these two treatment groups were observed in all of the specimens treated at various water infiltration periods (p<0.05). The exposure of internal pores and micro-cracks in the surface due to polishing of the fired specimens influenced mechanical behaviors. Especially, the flexural strength in specimens without glazing treatment has shown significant degradation with the infiltration of water. Therefore, this study suggests that glazing processes can improve mechanical properties of dental porcelain.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.88-93
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• 2005

The functional vice (Oryza sativa L.) has been highly regarded recently, in the change of rice maykets in the world. Goami2 (GA), one of the functional rice varieties, was developed from high-quality rice, Ilpumbyeo (IP). From the previous study, GA has been proved its beneficial effect on the improvement of metabolic control and body weight reduction especially in obesity, We could certain that GA was very difficult to be gelatinized due to the micro lump shown in the Scanning electron micrographs (SEM) photos. To improve its cooking quality, we investigated the changes of physicochemical properties, which were differentiated by the conditions of milling and blending. As GA was milled every $2\%$ until eliminating $12\%$, the nitrogen content was decreased linearly. But the decreasing rate of nitrogen content of GA during milling process was relatively lower than that of IP. Thus, we assumed that GA has relatively high nitrogen in inner starch of grain. The degree of milling had no effect on the gelatinization of cooked GA, but affected lightness and whiteness linearly, which were ranged in normal values when the rice was milled more than $10\%$ in weight. So we could concluded that the milling process was not proper to improve cooking quality of GA. And we could suggested that GA was needed to soak into water at least one hour before cooking by it water absorption rate at normal temperature$(21^{\circ}C)$ and sensory evaluation. From the texture analysis, cooked GA had higher hardness than other varieties. Therefore, we blended GA with IP, Baekjinju(BJ) and Hwasunchalbyeo(HS), then subjected to sensory evaluation. All evaluation items including the sensory preference were the highest scores for the rice blended with glutinous rice varieties, BJ and HS.

• Tribology and Lubricants
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• v.34 no.3
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• pp.84-92
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• 2018

Bearings are essential for reducing vibration and wear, in order to achieve high durability and increase longevity. White metal treatment of tilting pads via centrifugal casting method has the possibility of increasing durability. However, this manufacturing method has drawbacks such as long processing time, high defect rate, and harmful health effects. Laser cladding deposition technique is a powerful method that can address these issues by decreasing the processing time and providing good adhesion. In this study, we suggest optimum conditions for laser cladding deposition that can be used in industrial applications. We deposited a soft white metal layer on SCM440 that is primarily used in shafts to minimize wear of bearing pads. During the laser deposition process, we controlled factors such as laser power, powder feed rate, and laser head speed to determine the optimum conditions. In addition, we measured the hardness using micro Vickers, and performed field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and friction tests to investigate the mechanical properties and surface characteristics for different parameters. Based on the experimental results, we suggest that laser power, powder feed rate, and laser head speed of 1.3 kW, 2.5 rpm, and 10 mm/s, respectively, constitute the optimum conditions for producing white metals using laser cladding.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.14-21
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• 1992

Allanite crystals rich in rare-earth elements(REE) occur in soil developed on top of anorthositic rocks in the Jungsu-ri area of Okjong-myun, Hadong-run, where large Ti orebodies are embedded in the bed rock. In this study allanite is investigated mainly by transmitted light microscopy, electron microprobe analysis, atomic absoption spectrophotometry, X-ray diffraction, infrared spectrocopy. In addition, its specific gravity and micro=indentation hardness value are measured. Allanite occurs with max. dimension of $3cm{\times}6cm$ and coexists with quartz, epidote, zircon, biotite and muscovite. It shows nearly nonmetamict crystallinity, although ${\alpha}$-particles bombardment from the disintegration of the radioactive element Th is detected by an autoradiography. The allanite is particularly enriched in REE(19.88-23.99 wt.%), but is deficient in CaO(8.35-10.29wt.%). Genesis of the allanite in this area is not understood yet. It is, however, assumed to have been formed from magmatic fluid rich in REE and Ti, based on the facts that it ocexists with zircon and that it has high $TiO_2$(0.89-1.13 wt.%) whose concentration is significant in the country rocks.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1137-1143
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• 1999

Microstructure and mechanical properties of Mod.9Cr-1Mo and W added 9Cr-0.5Mo2W steels were investigated for liquid metal reactor (LMR) heat exchange tube. The tempering temperatures at which cell structure was formed were $700^{\circ}C$ for Mod.9Cr-1Mo steel and $750^{\circ}C$ for W added 9Cr0.5Mo-2W steel. indicating the recovery of dislocation was delayed by the addition of W. 9Cr-0.5Mo-2W steel had the same kinds of precipitates with Mod.9Cr-1Mo steel, but the W was included in the precipitates in 9Cr-0.5Mo-2W steel. Micro-hardness and ultimate tensile strength of 9Cr-0.5Mo-2W steel were higher than those of Mod.9Cr-1Mo steel. The impact property of Mod.9Cr-1Mo steel was superior to that of 9Cr-0.5Mo-2W steel.

• Journal of Conservation Science
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• v.32 no.4
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• pp.459-469
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• 2016

The goal of this study was to examine property changes induced by the choice of filler used with an epoxy resin that was developed in 2014 to restore cultural assets and consider the applicability of the resin as a restorative agent. The properties of putty mixed with 9 types of fillers and as-developed resins were compared with those of existing materials with regard to stability, superiority and applicability. The potential of the putty as an alternative material was also examined. The materials produced the best adhesiveness, color change and hardness results when mixed with lime. Micro balloon produced the best wear rates and hardening times, while diatomite produced the best tensile and compressive strengths. A plaster and white mineral pigment mixture produced the best specific gravity. Every material except for lime exhibited about 2.5-20 times higher wear rates than the existing material, which is thought to exhibit an excellent cutting force. The hardening time was enhanced by about 0.5-9 times to improve convenience. The stability of the relic was also ensured by improving hand staining without any shrinkage or deformation. The material exhibited about 0.5-27 times less yellowing. Thus, it is thought to be a material that can reduce property changes and reduce the degree of relic fatigue which occurs during reprocessing and sense of difference from relic.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.918-924
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• 1998

This study has been carried out to investigate the effect of reaction milling time on the synthesis of Ti- TiC p powder synthesised from the elemental titanium and activated carbon by reaction milling(RM), and the effect of vacu­u urn hot pressing temperature and TiC volume fraction on microstructural and mechanical properties of Ti- TiC com­p posite $\infty$ns이idated by vacuum hot pressing(VHP).T The elemental powders of titanium and activated carbon can be converted into Ti- TiC composite powders by reac­t tion milling for about 300hours, and were the average grain size of the as- milled powders has been measured to be a about $5\mu\textrm{m}$. The relative density of Ti- TiC VHPed above $1000^{\circ}C$ during Ihr is about 98% and the mechanical properties o of In- situ Ti- TiC composites are improved by TiC particle dispersed uniformly on titanium matrix. In order to investi­g gate thermal stability of Ti- TiC composite, after annealing at $600^{\circ}C$ for 80hrs micro- Vickers hardness have been per­f formed, and the values have been shown little changed as compared with those before annealing. The compact has b been tested on high temperature compressive test at $700^{\circ}C$ and has showed a high temperature compressive strength of 330MPa in a Ti- 20vol% TiC.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.312-318
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• 2008

In a pear fruit 'Chuhwangbae' was investigated the effect of the calcium-coated double paper bag on the physical properties of the paper bag, micro meteorological phenomena, and calcium contents in quality of fruit. The calcium-coated paper bag, compared with official paper bags, did not give any effect on light transmission ratio and tensile strength. The change of the inside relative humidity of the paper bag was a little compared with conventional paper bags, but there was no difference in temperature. The contents of the accumulated calcium of the pericarp was remarkably greater than conventional paper bags during the period of 65 days to 160 days after the full bloom, but the flesh remarkably increased at 160 days. The calcium content per concentration of calcium coating greatly increased in 12% of yellow double paper bags and 9, 12% of newspaper double paper bags in case of the pericarp, and in 3% of yellow double paper bags and 6, 9, 12% of newspaper double paper bags in case of the pericarp. As a result of treatment of a radioactive isotope, the amount of accumulated calcium in the pericarp continued until 60 hours after treatment, but there was no difference in the calcium amount between the flesh and no-treatment pericarp. As to the hardness of fruits at the time of harvest, there was no difference in the concentration in case of a yellow double bags. But newspaper double paper bags 6, 12% was significantly difference. Soluble solid remarkably increased in yellow double paper bags 6, 9% and yellow double paper bags 3, 6, 9%. Also, it did not effect on changes of the pericarp, fruit weight and the color of the pericarp.