• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.72-77
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• 2019

In this study, the wear characteristics of end mills for CFRP processing were investigated according to the tool materials and coating types. Three kinds of tool materials and two types of coatings were used for comparing the machining performance. The flank wear of the end mill tool and the surface condition of the workpiece were compared. The K6UF material shows the most excellent performance among the three materials used in the experiment. The Tetrabond coating showed better processability in comparison of two kinds of coatings.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.1-5
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• 2021

Field-effect transistors based on solution-processed metal oxide semiconductors has attracted huge attention due to their intrinsic characteristics of optical and electrical characteristics with benefits of simple and low-cost process. Especially, spray-pyrolysis has shown excellent device performance which compatible to vacuum-processed Field-effect transistors. However, the high annealing temperature for crystallization of MOS and narrow range of precursors has impeded the progress of the technology. Here, we demonstrated the nc-ZnO/ZnO films performed by spray-pyrolysis with incorporating ZnO nanoparticles into typical ZnO precursor. The films exhibit preserving morphological properties of poly-crystalline ZnO and enhanced electrical characteristics with potential for low-temperature processability. The influence of nanoparticles within the film was also researched for realizing ZnO films providing good quality of performance.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.78-81
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• 2012

Colloidal titania nanoparticles were synthesized by a simple sol-gel process. The obtained nanoparticles showed high crystallinity and were of the anatase type. These crystalline colloidal titania nanoparticles were organically modified using methyl- and glycidyl-grafted silanes in order to enhance their stability and solution processability. The stabilized colloidal titania nanoparticles could be dispersed homogeneously without aggregation and converted into silica-titania hybrid films with the heterogeneous Si-O-Ti bonds by a low-temperature solution process. The fabricated silica-titania hybrid films showed high transparency (~ 90%) in the visible range, and low RMS roughness (<1 nm). Therefore, the organosilane-modified crystalline colloidal titania nanoparticles can be used in solution-processable functional coatings for electro-optical devices.

• Composites Research
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• v.24 no.4
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• pp.23-28
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• 2011

Recently CFRP laminate joints process by bolts and nets are developed rapidly in aircraft industries. However, there are serious drawback during jointing process. Many hole processes are needed for the manufacturing and structural applications using composite materials. Generally, very durable polycrystalline crystalline diamond (PCD) drill has been used for the CFRP hole process. However, due to the expensive price and slow process speed, chemical vapor deposition (CVD) diamond drill has been used increasingly which are relatively-low durability but easily-adjustable process speed via drill shape change and price is much lower. In this study, the comparison of hole process between PCD and CVD diamond coated drills was done. First of all, CFRP hole processbility was evaluated using the equations of hole processing conditions (feed amount per blade, feed speed). The comparison on thermal damage occurring from the CFRP specimen was also studied during drilling process. Empirical equation was made from the temperature photo profile being taken during hole process by infrared thermal camera. In addition, hole processability was compared by checking hole inside condition upon chip exhausting state for two drills. Generally, although the PCD can exhibit better hole processability, hole processing speed of CVD diamond drill exhibited faster than PCD case.

• The Korean Journal of Food And Nutrition
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• v.33 no.3
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• pp.287-298
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• 2020

When producing rice products, it is very important to select suitable raw materials. Therefore, in this study, the quality characteristics of 16 rice cultivars were quantified to determine the criteria for evaluating the machinability of raw rice. The L value, which can affect the color of porridge prepared from rice, was the greatest for Hwaseonchalbyeo (84.17). The water-binding capacity, related to water interaction, was high in Hyangcheola (113.2%), and water solubility was high in Shingil (22.3%). Dodamssal (42.3%, 70.7 RVU) and Hwaseonchalbyeo (4.7%, 27.8 RVU) showed lower final viscosity compared to the cultivars in which the amylose content was medium groups (16.4~21.2%, 173.6~277.2 RVU). Specifically, cultivars with high or low amylose content had a low viscosity. The characteristics of the distribution of raw rice quality data were confirmed through 11 histograms. Furthermore, amylose content vs. water solubility, water solubility vs. peak viscosity, and peak viscosity vs. final viscosity showed high correlations (r=0.542, -0.569, and 0.836 respectively, p<0.01), and clear cultivar discrimination by the standard error of the mean (0.765~10.811). In conclusion, amylose content, water solubility, and peak viscosity were considered the most suitable characteristics for the quality evaluation of raw rice.

• Food Science and Preservation
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• v.16 no.5
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• pp.699-704
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• 2009

Commercially produced 'baby leaves' of Brassica campestris var. narinosa (Chinese cabbage) were used in the present study. Baby leaf vegetables were sown on 128 cell plug trays and harvested 30 days after sowing. For mechanical stress experiments, seedlings were thinned to three per cell, selected for uniformity, and watered at the base. Trays were treated with mechanical stress by stroking back and forth 50 times, using a sheet of A4 paper folded to double thickness. Plants were treated between 12:00 and 14:00 daily for 15-20 days. Harvested baby leaf vegetables were packed in MAP salad bags made of P-plus film, $50{\mu}m$ polypropylene (PP) film, and polyethylene terephthalate (PET) boxes. Fresh weight was well-maintained under P-plus and PP film on storage at $8^{\circ}C$. However, loss of fresh weight occurred quickly in PET boxes, and vegetable quality deteriorated rapidly. Stressed leaves were smaller but thicker, with an increased dry weight ratio. We thus suggest that P-plus or PP film is most appropriate packing for marketing of baby leaf vegetables, which should be stored at $8^{\circ}C$. Our data on baby leaf vegetables also make a significant new contribution in that we demonstrate a positive effect of stress touching on baby leaf processability.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.1-7
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• 2019

Purpose: The laser processability of dental prosthesis is investigated using two ceramic composites, including 3M, Lava Ultimate and Ivoclar vivadent, IPS e.max. Materials and methods: The $CO_2$ laser, picosecond laser and femtosecond laser are used to assess the processing power of dental prosthetic materials Lava Ultimate and IPS e.max and the line processing shape was measured using a confocal microscope. Results: The brittleness, carbonization and micro crack of the ceramic composite were influenced by heat accumulation of the material and could be controlled by the laser power and pulse time. Conclusion: In the case of $CO_2$ lasers, micro crack and carbonation occurred immediately, and in the picosecond laser processing, the micro cracks are partially improved, but the carbonization occurs continuously. Finally, we confirmed the high efficiency of laser processing with femtosecond laser. In particular, Lava Ultimate, a ceramic resin composite material, showed the best processability when processed using a femtosecond laser.

• Fibers and Polymers
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• v.7 no.4
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• pp.358-366
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• 2006

Thermotropic liquid crystal polymer (TLCP)-reinforced poly(butylene terephthalate) (PBT) composites were prepared by melt processing. The improvement in the mechanical properties and the processability of the PBT/TLCP composites was attributed to the reinforcing effect by TLCP phase and its well distribution in the PBT matrix. X-ray diffraction results demonstrated that a slow cooling process leads to the thicker lamellar structures and the formation of more regular crystallites in the composites. The incorporation of TLCP improves not only the tensile strength and flexural modulus but also the heat distortion temperature (HDT) of the PBT/TLCP composites. The HDT values of the composites were dependent on TLCP content. The improvement in the HDT values of the PBT/TLCP composites may be explained in terms with the increased flexural modulus, the development of more regular crystalline structures, and the enhancement of the ability of the composites to sustain the storage modulus by TLCP phase. In addition, the simple additivity rule makes it possible to predict the HDT values of the PBT/TLCP composites.

• Textile Coloration and Finishing
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• v.27 no.1
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• pp.35-49
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• 2015

This paper investigated optimum process conditions of coating yarn for awning fabric. For this purpose, the simulation for processability and yarn quality using SPSS statistics package was carried out, and PP/TPO and PET/PVC coating yarns specimens were made with variation of extruder temperature and feed speed of core yarn on the yarn coating machine for examining simulation result. It was revealed that optimum coating conditions of PP/TPO 1000d coating yarn were extruder temperature $150^{\circ}C$, and core yarn feed speed 400~500m/min. Mechanical property and thermal shrinkage of PP/TPO coating yarn made at this conditions were best and core evenness rates of these coating yarns by yarn compression tester were also superior, which was certified by SEM photograph. In addition, these experimental results were coincided with simulation results. It was found that, in PET/PVC coating yarn, yarn physical properties between 1500d and 1200d coated yarns were not shown any difference, and core evenness rates of these coating yarns were superior. It revealed and concluded that these simulated coating conditions are applicable to production field.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.195-202
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• 2004

This paper presents the fabrication and evaluation of mechanical behavior for a peristaltic micropump by flow simulation. The valve-less micropump using the diffuser/nozzle is consists of the lower plate, the middle plate, the upper plate and the tube that connects inlet and outlet of the pump. The lower plate includes the channel and the chamber, and the plain middle plate are made of glass and actuated by the piezoelectric translator. Channels and a chamber on the lower plate are fabricated on high processability silicon wafer by the DRIE(Deep Reactive Ion Etching) process. The upper plate does the roll of a pump cover and has inlet/outlet/electric holes. Three plates are laminated by the aligner and bonded by the anodic bonding process. Flow simulation is performed using error-reduced finite volume method (FVM). As results of the flow simulation and experiments, the single chamber pump has severe flow problems, such as a backflow and large fluctuation of a flow rate. It is proved that the double-chamber micropump proposed in this paper can reduce the drawback of the single-chamber one.