• Proceedings of the KWS Conference
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• 2004.05a
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• pp.144-145
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• 2004

Submerged arc welding technique using metal powder as supplementary filler metal has been studied. Forward feeding was used, and the deposit rate was increased by 50%. Good bead appearance, soundness and mechanical properties were obtained with feed rate of 120g/min..

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.118-120
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• 2007

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.373-379
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• 2010

This study was carried out to develop a belt pick-up type one-row soybean cutter, using physical properties and production conditions of soybeans. The prototype soybean cutter consisted of 4 parts: cutting part, conveying part, collecting part, and travelling part. The prototype soybean cutter was designed to cut soybeans planted with a row spacing of 600 mm, and at a height of 30 mm from the bed bottom using a disk saw. Through various trials with different peripheral velocities of the disk saw and forward speed of the cutter, determined ranges of the peripheral velocity of the disk saw cutting soybeans stems were greater than 18.3 m/s. Spacing between pick-up belts (clearance) was in a range of 60~90 mm so that soybeans could be picked at heights greater than 25 cm, and the size and shape of the pick-up belt were determined the conventional manual harvesting method. The optimal ratio between the forward speed of cutter and the peripheral speed of pick-up belts were from 1 to 1.2 by theoretical analysis. the pick-up belts had a $35^{\circ}$ of tilted angle and $90^{\circ}$ of twisted angle to pick up soybeans safely from the plant input to the lower end of the belts and convey soybeans to the upper end of belts nearby a container. The soybeans at the rear container were dropped down on the soybean row with an interval. The effective field capacity of the prototype soybean cutter was 0.136 ha/h, reducing the working hour by 92% when compared with the manual cutting.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.372-379
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• 2013

In this study, we investigated the traits of the clad metals used in hot-rolled clad steel plates. We examined the sensitization and mechanical properties of STS 316 steel plate and carbon steel (A516) under the specific circumstances of post heat treatment and whether a weld was multilayered and thick or repeated because of repairs. The test conditions were as follows. The clad steel plates were butt-welded using FCAW/SAW, and the heat treatment was conducted at $625^{\circ}C$, for 80, 160, 320, 640, or 1280 min. The change in the corrosion resistance was evaluated in these specimens. In the case of the carbon steel (A516), as the heat treatment time increased, the annealing effect caused the tensile strength to decrease. The micro- hardness gradually increased and then decreased after 640 min. The elongation and contraction of the area increased gradually. An oxalic acid etch test and EPR test on STS316, a clad metal, showed a STEP structure and no sensitization. From the test results for the multi-layered and repair welds, it could be concluded that there is no effect on the corrosion resistance of clad metals. In summary, the purpose of this study was to suggest some considerations when developing on-site techniques and evaluate the sensitization of stainless steels.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.327-333
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• 2000

Transversal SAW(Surface Acoustic Wave) filters of 340MHz were fabricated on piezoelectric substrates of the LN $128^{\circ}$ Y-X wafers. Both of spacing and width of IDT were $1.435{\mu}m$. For improving the power durability characteristics, titanium layer was inserted between aluminum electrode and piezoelectric substrate since it has high density, low thermal expansion coefficient, and good adhesive properties. Power durability was evaluated with respect to the thickness of inserted titanium layer and the temperature of heat treatment. Power durability is improved with increasing the thickness of the inserted titanium layer. Moreover, it is remarkably improved by heat treatment at the temperature of $300^{\circ}C$.

• Journal of Welding and Joining
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• v.23 no.2
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• pp.66-74
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• 2005

API(American Petroleum Institute) steel, as a line pipe material, requires the enhanced mechanical and chemical properties with the environmental severity. Especially, the weld part(weld metal and heat affected zone) is an important region for the safety. However, the study for the behavior of microstructure and toughness in multi-pass welding is seldom. In this study, the relationship between the microstructure and toughness of welds with several welding, bending and heat-treatment conditions was examined. In particular, HIC property in the weld metal was evaluated. The microstructure and toughness in multi-passed HAZ seemed to be determined by the final welding thermal cycle and the low toughness was attributed to the MA constituents formed in the intercritically reheated region. The weld metal showed very low toughness and it was not improved by the change in bending and heat treatment conditions. Additionally, the cracks are observed in the weld metal. from these results, it was found that the choice of welding wire/flux is very important.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.487-492
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• 2009

This study was performed FE numerical analysis under 120-minute fire conditions, using the ABAQUS, a wide use software, on the basis of the test results by concrete tunnel lining fire strengths (ISO, RWS, and MHC). The concrete material test was to secure the material properties of concrete linings, which were numerical analysis input conditions. And then built the material properties, such as specific heat, heat transfer rate, heat expansion rate, density, elasticity coefficient and compression strength under high temperature conditions, as database at 20 $^{\circ}C$ to 800 $^{\circ}C$, applying them to analysis as input values. As a result, the tunnel linings under RWS fire conditions saw fire temperature rose to maximum 1119 $^{\circ}C$at the location of 5 mm above a thermal surface, and saw surface temperature amount to 1214 $^{\circ}C$ in the middle part.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.128-129
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• 2006

To investigate impact property characteristics on the low temperature plate weld metal, the two different plates of the same steel grade were welded and evaluated by Mo bearing and no Mo containing welding consumables. The results are summarized as follows; 1) Multi pass welded Mo bearing weldment was not satisfied with the requirement of tensile strength, while no Mo containing one was satisfied with it 2) In the plate butt weldment, the impact property of weld metal was highly affected by both the welding consumable and plate.

• Journal of Welding and Joining
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• v.31 no.2
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• pp.49-56
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• 2013

We have investigated traits of clad metals in hot-rolled clad steel plates, sensitization and mechanical properties of STS 316 steel plate and carbon steel(A516). Clad steel plates were butt-weld by SAW+SMAW, and with the time of heat treatment as the variable, heat treatment was conducted at $625^{\circ}C$, for 80, 160, 320, 640, 1280 minutes. As a way to evaluate it, sectioned weldments and external surfaces were investigated to reveal the degree of sensitization by mechanical property, etching and those of EPR test, results were compared with it. In short, the purpose of this study is suggesting some considerations in developing on-site techniques to evaluate the sensitization of stainless steels.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.393-394
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• 2007

In this study, to minimize the above effect Zinc Oxide(ZnO) thin films on Si(100) substrate were deposited by RF magnetron sputter with changing sputtering conditions such as Ar/$O_2$ gas ratios, RF power, substrate temperature, chamber prsssure and target-substrate distance. To analyze a crystallographic properties of the films, ${\Theta}/2{\Theta}$ mode X-ray diffraction, rocking curve and Alpha-step were performed. SAW filters were fabricated to evaluate the feasibility of ZnO thin film as a piezoelectrical materials and the processes of ZnO SAW filters using etch and lift-off were compared.