• Journal of Welding and Joining
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• v.31 no.6
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• pp.58-64
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• 2013

Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.

• Journal of Surface Science and Engineering
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• v.47 no.5
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• pp.221-226
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• 2014

A low temperature plasma nitrocarburizng was implemented on the duplex stainless steel to achieve the enhancement of surface hardness without degradation of its corrosion resistance. Attempts were made to investigate the influence of Pulse frequency and Duty factor of pulsed power in a high Pulse frequency regime on the surface characteristics of the hardened layer. The hardened layer (S-phase) was formed on all of the treated surfaces. Surface hardness reached up to 1300 $HV_{0.1}$ which is about 4.6 times higher than that of the untreated material (280 $HV_{0.1}$). The thickness of the hardened layer tends to increase lightly with the higher Pulse frequency and the higher Duty factor. The corrosion resistance of nitrocarburized duplex stainless steel was almost similar to that of the untreated material. Both the Pulse frequency and the Duty factor do not have a significant influence on the corrosion property of plasma treated duplex stainless steel.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.224-232
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• 2012

In this study, the effect of hot-stamping heat treatment on the microstructure and hardness of TWB(Tailor Welded Blank) laser joints in Al-Si-coated boron steel and Zn-coated DP(Dual Phase)590 steel was investigated. In the TWB joints without heat treatment, hardness profiles showed local hardness deviation near the fusion zone. However, there was no hardness deviation in the heat treated specimen and its hardness was higher than that of the one without the heat treatment, due to a fully martensite microstructure. In the TWB joints of both the boron and DP steels, the maximum hardnesses were observed at the HAZ(Heat Affected Zone) near the base metal, and the hardness decreased gradually to the base metal. In the heat treated joints, the hardnesses of the HAZ and the base metal of the boron steel side were similar to the maximum hardness of the weld, while those of the HAZ and the base metal of the DP steel side were higher than the maximum hardness.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.956-966
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• 2011

Bioleaching studies of metals from a spent catalyst were conducted using both adapted and unadapted bacterial cultures. The bacterium used in this experiment was Acidithiobacillus ferrooxidans. A comparison of the kinetics of leaching was made between the two cultures by varying the leaching parameters, including the pulp density, particle size and temperature. Both cultures showed similar effects with respect to the above parameters, but the leaching rates of all metals were higher with the adapted compared to the unadapted bacterial cultures. The leaching reactions were continued for 240 h in the case of the unadapted bacterial culture, but only for 40 h in the case of the adapted bacterial culture. The leaching reactions followed first order kinetics. In addition, the kinetics of leaching was concluded to be a diffusion control model; therefore, the product layers were impervious.

• Cross-Cultural Studies
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• v.38
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• pp.351-384
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• 2015

This paper is concerned with the effectiveness of songs in the acquisition of formulaic sequences in the college EFL classroom. The existing research mentions the use of songs in terms of the power of their melodies (Fonseca-Mora, 2000), linguistic features in song lyrics (Abbott, 2002), and the emotional basis of memory (LI & Brand, 2009). Learners' opinions about the use of songs has been ignored, however. In this paper, seven subjects with English ability ranging from advanced (one) intermediate-high (three), intermediate-middle (two), and intermediate-low (one) studied five different pop songs. The results showed that they did not agree with the existing research findings. Rather, they were negative about using songs in the classroom. Their complaints were the burden of using too many hours to memorize lyrics, few language expressions to learn, and too much emphasis on expressions about love and feelings. Students at all levels expressed similar negativity about the use of songs. When their complaints were discussed during interviews, however, their attitude changed from negative to positive. The case study in this paper was on a small-scale but it is suggested that through further research the use of songs could be activated in the EFL classroom. Considering college language learners disregard most existing EFL materials, it appears to be worthwhile to continue further with this kind of research.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.1
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• pp.33-40
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• 1971

Using radioactive $^{40}K$ in potassium, a study was conducted to evaluate the potassium supplying power of different soil types developed on different parent materials. A conversion factor based on two parameters namely $\frac{available\;K_{soil}}{total\;K_{soil}}$ and $\frac{K_{plant}}{K_{soil}}$ was developed and found to be closely related to plant response. According to this characterization soils derived from the various parent materials were ranked as basalt >Silla series>gneiss>porphyry>granite${\gg}$schist. From the point of view of potassium response as measured by yield as similar response pattern was observed. That is, soils derived from basalt to be most responsive as compared to the other soils. The variations among the soils may be accounted for to their potassium bearing mineralogical composition and their stability.

• Journal of Fashion Business
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• v.25 no.4
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• pp.151-160
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• 2021

The purpose of this study was to investigate whether there were improvements on balance when both ankle-jointed calf muscles and hip muscles, which affect balance capabilities, were activated through taping techniques and EMS. In this study, the One Leg Standing Test, a static balance test, was conducted by experimenting on a flat floor, foam pad, and a stretching board with a gradient of 20 degrees, respectively, to study static balance capabilities in different situations. Nine healthy men in their 20s were measured five times every five minutes considering muscle fatigue, and the difference between each variable was analyzed through post-test using nonparametric statistical analysis. Our results showed an equal increase in static balance capability was similar when EMS was applied only to calf muscles and only to hip muscles. Notably most improvements were seen when wearing calf supporters and taping technology pants, and applying EMS together. It was also found that the difference between EMS electric stimulation and balance capability was greater when wearing and applying supporters and taping technology pants. Based on the results of the present study, a muscle support band and EMS of taping techniques can improve balance capabilities. These findings are expected to form a basis for solutions Improving the balance capabilities

• Corrosion Science and Technology
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• v.20 no.4
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• pp.189-195
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• 2021

A technology for designing and licensing a dedicated radiation shielding facility needs to be developed for safe and efficient operation an R&D center. Technology development is important for smooth operation of such facilities. Causes of damage to internal structures (such as baffle former bolt (BFB) of pressurized water reactor) of a nuclear power reactor should be analyzed along with prevention and countermeasures for similar cases of other plants. It is important to develop technologies that can comprehensively analyze various characteristics of internal structures of long term operated reactors. In high-temperature, high-pressure operating environment of nuclear power plants, cases of BFB cracks caused by irradiated assisted stress corrosion cracks (IASCC) have been reported overseas. The integrity of a reactor's internal structure has emerged as an important issue. Identifying the cause of the defect is requested by the Korean regulatory agency. It is also important to secure a foundation for testing technology to demonstrate the operating environment for medium-level irradiated testing materials. The demonstration testing facility can be used for research on material utilization of the plant, which might have highest fluence on the internal structure of a reactor globally.

• Environmental Engineering Research
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• v.24 no.1
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• pp.91-98
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• 2019

This study was to objectify differences in the results of odor testing according to the characteristics of panel members that participate in air dilution olfactory method (ADOM) testing. When differences in the results of olfactory testing were reviewed in relation to characteristics of the panelists, the result of entire panels for the site boundary Proficiency Testing Materials (PTMs) showed no difference according to panelist sex, age, smoking status, and past participation in ADOM tests. As for the outlet PTMs, distinct differences appeared in relation to the smoking status and age of panelists. The frequency distribution for all the panelists (Dev($D/T_{total}$)) showed a form similar to a normal distribution, so it is thought to be more appropriate for the review of effect of panelist characteristics on the result of air dilution olfactory tests. In addition, the ADOM testing method implemented as the standard method for odor compounds in Korea (Dev($D/T_3$)) will have to be implemented along with a concurrent assessment, for the purpose of identifying the effect of panelist characteristics on administrative dispositions against malodors.

• Tribology and Lubricants
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• v.35 no.1
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• pp.24-29
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• 2019

In this work we investigated the friction and wear characteristics of a magnesium alloy, which has been receiving much attention as a light metal in industrial applications such as automobiles and aerospace. Magnesium is one of the lightest structural material that has high specific strength, lightweight, low density and good formability. However, current issue of using magnesium alloy is that magnesium has weakness against temperature. As the temperature increases, magnesium undergoes poor creep resistance and ease of softening, and therefore, its mechanical strength decreases sharply. To solve this issue, a new type of magnesium alloy that retains high strength at high temperature has been proposed. The tribological behavior of this alloy was investigated using a tribotester with reciprocating motion and heating plate. A stainless steel ball was used as a counter surface. Results showed that extrusion process has similar wear behavior to the commonly used casting process but retains good mechanical strength and durability. The presence of an alloying element enhanced the wear properties especially in high temperature. This study is expected to be utilized as fundamental data for the replacement of high density materials currently used in mechanical industries to a much lighter and durable heat-resistant materials.