• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.845-852
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• 2011

The Spark Plasma Sintering(SPS) method offers a means of fabricating a sintered-body having high density without grain growth through short sintering time and a one-step process. A titanium compact having high density and purity was fabricated by the SPS process. It can be used to fabricate a Ti sputtering target with controlled parameters such as sintering temperature, heating rate, and pressure to establish the optimized processing conditions. The compact/target(?) has a diameter of ${\Phi}150{\times}6.35mm$. The density, purity, phase transformation, and microstructure of the Ti compact were analyzed by Archimedes, ICP, XRD and FE-SEM. A Ti thin-film fabricated on a $Si/SiO_2$ substrate by a sputtering device (SRN-100) was analyzed by XRD, TEM, and SIMS. Density and grain size were up to 99% and below $40{\mu}m$, respectively. The specific resistivity of the optimized Ti target was $8.63{\times}10^{-6}{\Omega}{\cdot}cm$.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.653-658
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• 2018

$ZrO_2$ is a candidate material for hip and knee joint replacements because of its excellent combination of biocompatibility, corrosion resistance and low density. However, the drawback of pure $ZrO_2$ is a low fracture toughness at room temperature. One of the most obvious tactics to cope with this problem is to fabricate a nanostructured composite material. Nanomaterials can be produced with improved mechanical properties(hardness and fracture toughness). The high-frequency induction heated sintering method takes advantage of simultaneously applying induced current and mechanical pressure during sintering. As a result, nanostructured materials can be achieved within very short time. In this study, W and $ZrO_2$ nanopowders are mechanochemically synthesized from $WO_3$ and Zr powders according to the reaction($WO_3+3/2Zr{\rightarrow}W+3/2ZrO_2$). The milled powders are then sintered using high-frequency induction heating within two minutes under the uniaxial pressure of 80MPa. The average fracture toughness and hardness of the nanostructured W-3/2 $ZrO_2$ composite sintered at $1300^{\circ}C$ are $540kg/mm^2$ and $5MPa{\cdot}m^{1/2}$, respectively. The fracture toughness of the composite is higher than that of monolithic $ZrO_2$. The phase and microstructure of the composite is also investigated by XRD and FE-SEM.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.53-60
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• 2018

In this paper, the effect of different 3D printing parameters including laminated angle and annealing temperature is observed their effect on FDM conductive 3D printing. In FDM 3D printing, a conductive filament is heated quickly, extruded, and then cooled rapidly. FDM 3D Print conductive filament is a poor heat conductor, it heats and cools unevenly causing the rapid heating and cooling to create internal stress. when the printed conductive specimens this internal stress can be increase electrical resistance and decrease electrical conductivity. Therefore, This experiment would like to use annealing to remove internal stress and increase electrical conductivity. The result of experiment when 3D printing conductive specimen be oven cooling of annealing temperature $120^{\circ}C$ electrical resistance appeared decrease than before annealing. So We have found that 3D printing annealing removes internal stresses and increases the electrical conductivity of printed specimens. These results are very useful for making conductive 3D printing electronic circuit, sensor ect...with electrical conductance suitable for the application.

• Journal of IKEEE
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• v.23 no.1
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• pp.295-301
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• 2019

A heater in a portable real-time polymerase chain reaction(PCR) system is one of the important factors for controlling the PCR thermocycle precisely. Since heaters are integrated on a small-sized PCR chip for rapid heating and fabricated by semiconductor processes, the cost of producing PCR chips is high. Here, we propose to use chip resistors as an inexpensive and accurate temperature control method. The temperature distribution was simulated using one or two chip resistors on a real-time PCR chip and the PCR chip with uniform temperature distribution was fabricated. The temperature rise and fall rates were $18^{\circ}C/s$ and $3^{\circ}C/s$, respectively.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.2
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• pp.3-11
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• 2018

Korea has achieved a rapid economic development and with the increase in population and national income and the expansion of social and economic activities, energy consumption has rapidly increased too. Energy consumption per head has constantly increased and currently, power consumption per head is 7.5 times bigger than in 1985. Buildings occupy 25% of total energy consumption and especially, 50% of total energy is consumed for heating and cooling. In this situation, multi-family housing, which has constantly been increased, has an energy saving rate of 1.9%, which is the lowest level and this makes the government's energy policy for sustainable energy system development useless. Besides, energy consumption leads to secondary problems, such as air, water and marine pollution and heat pollution and wastewater/drainage and the increased use of fossil fuel is a fundamental reason for ozone layer destruction and global warming. Therefore, efficient energy consumption plans are required. This study aims to analyze energy performance in each block type of high-rise and diversified multi-family housing that accounts for 60% of all the housing forms, depending on the variations in stories through BIM-based energy simulation. For this study, four representative block types were selected, based on the multi-family floor plan, which is certified for energy performance evaluation and they were applied to the floor plan of a multi-family house that is scheduled to be built. Then BIM modeling was conducted from the fifth story to the 40th story at an intervals of 5 stories and based on the finding, energy characteristics of each block type and energy performance depending on the variations in stories were analyzed. It is considered that this would serve as objective data for block type and block story decision of energy performance-based multi-family housing.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.6
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• pp.1154-1162
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• 2020

In this study, the soft textile actuator is produced for a smart wearable with the shape memory effects from linear shape memory alloys of Nickel and Titanium using the driving force through the fabrication process. The measurement model was designed to measure dynamic characteristics. The heating method, and memory shape of the linear shape memory alloy were set to measure the operating temperature. A shape memory alloy at 40.13℃, was used to heat the alloy with a power supply for the selective operation and rapid reaction speed. The required amount of current was obtained by calculating the amount of heat and (considering the prevention of overheating) set to 1.3 A. The fabrication process produced a soft textile actuator using a stitching technique for linear shape memory alloys at 0.5 mm intervals in the general fabric. The dynamic characteristics of linear shape memory alloys and actuators were measured and compared. For manufactured soft textile actuators, up to 0.8 N, twice the force of the single linear shape memory alloy, 0.38 N, and the response time was measured at 50 s.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.614-618
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• 2011

Nanopowders of MgO, $Al_2O_3$ and $SiO_2$ were made by high energy ball milling. The rapid sintering of nanostructured $MgAl_2O_4-Mg_2SiO_4$ composites was investigated by a high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Highly dense nanostructured $MgAl_2O_4-Mg_2SiO_4$ composites were produced with simultaneous application of 80MPa pressure and induced output current of total power capacity (15 kW) within 2min. The sintering behavior, gain size and mechanical properties of $MgAl_2O_4-Mg_2SiO_4$ composites were investigated.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1618-1618
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• 2001

Predicting quality traits using near infrared (NIR) spectroscopy on whole grain samples has gained wide acceptance as a non-destructive, rapid and cost effective technique. Barley breeding programs throughout southern Australia currently use this technology as a tool for selecting malting quality lines. For the past 3 years whole grain barley calibrations have been developed at VIDA to predict malting quality traits in the early generation selections of the breeding program. More recently calibrations for whole grain malt have been developed and introduced to aid in selecting malted samples at the mid-generation stage for more complex malting quality traits. Using the same population set, barley and malt calibrations were developed to predict hot water extracts (EBC and IoB), diastatic power, free $\alpha$-amino nitrogen, soluble protein, wort $\beta$-glucan and $\beta$-glucanase. The correlation coefficients between NIR predicted values and laboratory methods for malt were all highly significant ($R^2$ > 0.84), whereas the correlation coefficients for the barley calibrations were lower ($R^2$ > 0.57) but still significant. The magnitude of the error in predicting hot water extract, diastatic power and wort $\beta$-glucan using whole grain malt was reduced by 50% when compared with predicting the same trait using whole grain barley. This can be explained by the complex nature of attempting to develop calibrations on whole grain barley utilizing malt data. During malting, the composition of barley is modified by the action of enzymes throughout the steeping and germination stages and by heating during the kilning stage. Predicting malting quality on whole grain malt is a more reliable alternative to predicting whole grain barley, although there is the added expense of micro-malting the samples. The ability to apply barley and malt calibrations to different generations is an advantage to a barley breeding program that requires thousands of samples to be assessed each year.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.641-648
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• 2023

Recently, the rapid growth of artificial intelligence among the 4th industrial revolution has progressed based on the performance improvement of semiconductor, and circuit integration. According to transistors, which help operation of internal electronic devices and equipment that have been progressed to be more complicated and miniaturized, the control of heat generation and improvement of heat dissipation efficiency have emerged as new performance indicators. The DUT(Device Under Test) Shell is equipment which detects malfunction transistor by evaluating the durability of transistor through heat dissipation in a state where the power is cut off at an arbitrary heating point applying the rating current to inspect the transistor. Since the DUT shell can test more transistor at the same time according to the heat dissipation structure inside the equipment, the heat dissipation efficiency has a direct relationship with the malfunction transistor detection efficiency. Thus, in this paper, we propose various method for PCB configuration structure to optimize heat dissipation of DUT shell and we also propose various transformation and thermal analysis of optimal DUT shell using computational fluid dynamics.

• Transactions of Materials Processing
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• v.33 no.3
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• pp.161-168
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• 2024

Aluminum alloy sheets, compared to conventional steel sheets, face challenges in press forming due to their lower elongation. To enhance their formability, extensive research has focused on forming technologies at elevated temperatures, specifically warm forming at around 300℃ and hot forming at approximately 500℃. This study proposes that the formability of aluminum alloy sheets can be significantly enhanced using a multi-stage hot forming technique. The research also investigates whether the strength of the A6061 aluminum alloy, known for its precipitation hardening, can be maintained when formed below the precipitate solid solution temperature. In the experiments, the A6061-T6 sheet underwent heating and rapid cooling between 250 and 500℃. The mechanical properties were evaluated at each stage of the process. The findings revealed that when the initial heat treatment was below 350℃, the strength of the material remained unchanged. However, at temperatures above 400℃, there was a noticeable decrease in strength coupled with an increase in elongation. Conversely, when the secondary heat treatment was conducted at temperatures of 350℃ or lower, the strength remained comparable to that of the initial heat treated material. However, at higher temperatures, a reduction in strength and an increase in elongation were observed.