• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.70-71
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• 2021

An increasing amount of red mud (RM) is being generated globally with the growth in alumi-num production. To avoid the RM becoming a pollutant, methods for effectively recycling RM at a low cost are being investigated. This study proposes a method for recycling RM as a construc-tion material. The cement paste with neutralized liquefied red mud had higher compressive strength than that of plain cement paste and cement paste with liquefied red mud without neutralization at 1 d of aging; this indicates that nitric acid neu-tralization increases the early-age strength.

• Journal of Koreanology Reviews
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• v.1 no.1
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• pp.25-29
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• 2022

Economic growth is one of the significant benchmarks determining a country's sustainable growth. Before WWII, most countries perceived their priority in terms of military strength as they dedicated most of their efforts and resources to creating weapons of mass destruction. The current research aims to establish some of the significant factors that may have contributed to the sustainable and progressive economic growth of South Korea within the 60-year timeframe. Multiple prior studies have attributed the economic growth in South Korea to policy reforms that opened the country to foreign markets. The outstanding increase in the percentage of exports stands out as an indication of the improvement in the quality of goods produced in the country. Finally, in recent years, China has dedicated more resources to research and developments as a strategy to improve innovation within the country and its overall economic growth. Other issues of concern likely to undermine the prospects of the country's economic growth include the limited geographical size, aging population, and limited natural resources. As such, South Korea needs to emphasize innovation and improve the business environment as its main strategy for sustainable economic growth in the future to maintain its continuous economic miracle.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.125-130
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• 2004

The effect of SiC particle size on the microstructures and mechanical properties of A1$_2$O$_3$-SiC composite was investigated. Two types of SiC powders having average particle sizes of 0.15 ${\mu}{\textrm}{m}$ and 3 ${\mu}{\textrm}{m}$ were used. The grain growth in the specimen containing 0.15 ${\mu}{\textrm}{m}$ SiC was effectively inhibited due to the fine SiC particles. However, after the formation of some abnormal grains, fast and exaggerated grain growth occurred which led to the microstructure of large grains with irregular shape. Fracture strength decreased due to the abnormal large grains. On the other hand, for specimen containing 3 ${\mu}{\textrm}{m}$ SiC showed normal grain growth behavior from initial sintering stage. Large SiC particles, however, effectively inhibited exaggerated grain growth after nucleation of a few abnormal grains. As a consequence, microstructure consisted of homogeneous elongated grains. In the A1$_2$O$_3$-2.5SiC(0.15 ${\mu}{\textrm}{m}$)-2.5SIC(3 ${\mu}{\textrm}{m}$) composite fabricated by mixing the two types of SiC powder, abnormal grain growth occurred. However, the good fracture strength was maintained regardless of microstructural changes in this specimen.

• Korean Security Journal
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• no.57
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• pp.85-110
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• 2018

The bodyguard is continuously training basic physical training and security art martial to protect the privacy of security target, prepare and deal with external contingencies and threats. Currently, university students majoring in security are required to take a judo class, one of their security art martial, which can use a technology to catch, crush and repress opponent. Therefore, this study identified the effects of systematic training on body composition, Performance fitness, growth hormones, and IGF-1 among male university students through a 10-week judo training program so that it was committed to providing objective data to enhance the value of judo as a security art martial and as a result, we have a conclusion as follows: After 10 weeks of judo training, muscle mass increased significantly, and body fat rate and BMI decreased significantly. The muscular strength and power of Performance fitness were shown to increase significantly, and growth hormones were shown to increase significantly. In total, the above results showed that for judo training university students, overall body composition improved positively, the muscular strength and power of active physical fitness improved, and growth hormones increased. Thus, the increase in muscle strength and growth hormones through judo training will encourage fat breakdown due to the development of the body's muscles and increase bone density in the spine, thereby reducing the risk of fractures and preventing injury to the trainees who are performing a security art martial. It will also greatly help your health by preventing obesity, cardiovascular and metabolic diseases, which eventually will enhance your bodyguard function and prolong your life as a bodyguard.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.425-428
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• 1996

Treeing deterioration which is one of the main cause of breakdown in insulating materials is affected by temperature, applied voltage and frequency. In this study, GN was introduced to improve impact strength of DGEBA/MDA system and the temperature dependence of AC treeing deterioration in this system was investigated. Dielectric breakdown strength decreased with the increment of temperature. As temperature increased, the growth rate of tree Increased.

• Journal of Ocean Engineering and Technology
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• v.18 no.5
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• pp.43-49
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• 2004

The lightness of components required in the automobile and machine industry necessitates the use of high strength components. In particular, the fatigue failure phenomena, which occurs when using metal, increases the danger to human life and property. Therefore, antifatigue failure technology is an integral part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel, while improving the fatigue strength on surface. Therefore, in this paper, the effect of compressive residual stress of spring steel(JISG SUP-9) by shot-peening on fatigue crack growth characteristics in a stress ratio(R=0.1, R=0.3, R=0.6) was investigated, giving consideration to fracture mechanics. By using the methods mentioned above, following conclusions are drawn: (1) The fatigue crack growth rate(da/dN) of the shot-peening material was lower than that of the un-peening material and in stage I, ΔKth, the threshold stress intensity factor of the shot-peen processed material is high in critical parts, unlike the un-peening material. Also m, fatigue crack growth exponent and number of cycle of the shot-peening material, was higher than that of the un-peening material, as concluded from effect of da/dN. (2) Fatigue life shows more improvement in the shot-peening material than in the un-peening material, and the compressive residual stress of surface on the shot-peen processed operate resistance of fatigue crack propagation.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.523-530
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• 2015

This study was tested growth hormone and fatigue materials after eight-week high-intensity interval exercise to middle aged women (40's~50's women) who have been obesity without other disease. Two group of 20 candidates were randomly divided 10 persons as exercise group and control group. Exercise was conducted 8 weeks 4 days 35 minutes, before the study each group was checked vital sign for fatigue materials. It showed the following results. First, it has been increased growth hormone level after exercise program compared each group, significantly. Secondly, it has been decreased fatigue materials due to the high-strength interval workout for 8 weeks compared control as significantly. As a result, eight-week high-intensity interval exercise could be increased growth hormone levels by reducing fatigue and it might be preventing fatigue materials levels. We would suggest that high-strength interval workout for 8 weeks could have a positive effect for preventing and reducing fatigue and related disease, obesity.

• Journal of Plant Biotechnology
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• v.31 no.4
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• pp.295-300
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• 2004

This article was conducted to induce the transgenic hairy roots and determine the effect of culture conditions on optimum growth of hairy roots by Agrobacterium rhizogenes strain, 15834 in Lycium chinense Miller. Hairy roots of L. chinense Miller. were induced from leaf segments by co-cultivation with A. rhizogenes. When the hairy roots were cultured in various MS medium strength and sucrose concentrations, the highest growth of hairy roots was observed in half-strength MS media supplemented with 3% sucrose, respectively. In air lift bioreactor cultures, the liquid medium contained with 1/2 MS and 3% sucrose was also the best for optimum growth of hairy roots.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.604-611
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• 2000

Glass-ceramics containing a cordierite (2MgO-2Al2O3-5SiO2) as a main crystal phase was prepared from MgO-Al2O3-SiO2 system glass through a controlled 2-step heat treatment for the application to magnetic memory disk substrate for higher storage capacity. Parent glasses prepared with addition of CeO2 as a fulx and TiO2 as a nucleating agent were crystallized by a 2-step heat treatment i.e. nucleation and crystal grwoth. Then the maximum nucleation and crystal growth rates were investigated and several properties such as bending strength, surface hardness and surface roughness were also studied for heat treated glass. As a result, only a $\alpha$-cordierite was precipitated as a main crystal phase for all heat treatment conditions and the maximum nucleation and crystal growth rates were 2.4$\times$109/㎣.hr at 80$0^{\circ}C$ and 0.3${\mu}{\textrm}{m}$/hr at 915$^{\circ}C$ respectively. After being nucleated at 80$0^{\circ}C$ for 5 hours and then crystallized at 915$^{\circ}C$ for 1 hour, the heat treated glass had a crystal volume fraction of 17.6% and crystal size fo 0.3${\mu}{\textrm}{m}$, and showed the optimum properties for the application to magnetic memory disk substrates as follows. ; Bending strength of 192 MPa, Vidkers hardness of 642.1kgf/$\textrm{mm}^2$, and surface roughness of 27$\AA$.

• Computers and Concrete
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• v.19 no.4
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• pp.429-434
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• 2017

Failure of basic structures material is usually accompanied by expansion of interior cracks due to stress concentration at the cracks tip. This phenomenon shows the importance of examination of the failure behavior of concrete structures. To this end, 4 types of mortar samples with different amounts of nano-silica (0%, 0.5%, 1%, and 1.5%) were made to prepare twelve $50{\times}50{\times}50mm$ cubic samples. The goal of this study was to describe the failure and micro-crack growth behavior of the cement mortars in presence of nano-silica particles and control mortars during different curing days. Failure of mortar samples under compressive strength were sensed with acoustic emission technique (AET) at different curing days. It was concluded that the addition of nano-silica particles could modify failure and micro-crack growth behavior of mortar samples. Also, monitoring of acoustic emission parameters exposed differences in failure behavior due to the addition of the nanoparticles. Mortar samples of nano-silica particles revealed stronger shear mode characteristics than those without nanoparticles, which revealed high acoustic activity due to heterogeneous matrix. It is worth mentioning that the highest compressive strength for 3 and 7 test ages obtained from samples with the addition of 1.5% nano-silica particles. On the other hand maximum compressive strength of 28 curing days obtained from samples with 1% combination of nano-silica particles.