• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.137-142
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• 1997

Spot welding has been used in the sheet metal joining processes because of its high productivity and convenience. In this study effects of welding conditions on the fatigue life and predicting methods of fatigue life of spot welded joint have been studied. Fatigue life was estimated by stress index parameter considering multiaxial stresses. Fatigue tests were conducted with the tensile-shear specimens using SPCC. Fatigue life of spot welded joint was influenced by welding currents and was predicted exactly with taking into account Stage III.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.157.2-158
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• 2001

• The Journal of Information Systems
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• v.6 no.2
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• pp.165-188
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• 1997

This paper describes about the development of the 3 Dimensional interactive physics experiment system using virtual reality technologies. Until now, most of the computer aided education systems have adopted one-sided learning way which only shows or tells. It excludes students during learning processes. To solve the problems of the one-sided learning way and to improve the educational productivity, the 3 Dimensional interactive physics experiment system is developed. The 3 Dimensional interactive physics experiment system introduced in this paper provides a new learning motivation for students and improves their educational effects through the 3 Dimensional graphics, realtime action, and realistic interactive experiment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.293-298
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• 1999

To make use of various switches, relays, and control instruments, a connector (jack) is used to link the battery (power) and operating units. A connector must have precision as well as solidity to control the power in a car. To improve productivity, we researched and developed a connector molding by adapting vacuum system and we've made it possible to minimize the incomplete molding and weld-line. As a result, good quality can be warranted with less costs.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2005.09a
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• pp.37-40
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• 2005

• Journal of the korean veterinary medical association
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• v.33 no.12
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• pp.743-748
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• 1997

Doramectin(DECTOMAXR), 25-cyclohexyl avermectin, which has acaricidal and anthelmintic effect was evaluated against the natural infestations of Sarcoptes scabiei var suis and GI nematodes(Ascaris suum and Trichuris suis) as measured by litter size and wei

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.569-578
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• 2015

Cold water paddy field soils are relatively unproductive, but can be ameliorated by supplementing with inorganic fertilizer from animal waste-based composts. The yield of two rice cultivars was significantly raised by providing either chicken manure or cow dung-based compost. The application of these composts raised the soil pH as well as both the total nitrogen and ammonium nitrogen content, which improved the soil's fertility and raised its nitrification potential. The composts had a measurable effect on the abundance of nitrogencycling-related soil microbes, as measured by estimating the copy number of various bacterial and archaeal genes using quantitative real-time PCR. The abundance of ammonia oxidizing archaea and bacteria was markedly encouraged by the application of chicken manure-based compost. Supplementation with the composts helped promote the availability of soil nitrogen in the cold water paddy field, thereby improving the soil's productivity and increasing the yield of the rice crop.

• Information Systems Review
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• v.11 no.3
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• pp.169-189
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• 2009

Over the past three decades, the impact of information technology (IT) investments on firm performance has been the subject of active research. Despite increasing importance of research into the productivity of IT in developing countries, almost all findings on IT productivity have been based on data collected in developed countries. This study investigates the effects of IT investment on firms' financial performance in the insurance industry of Korea, which is OECD member and can be classified as a developed country in IT perspective, and in the electronics industry of China, which is a developing country, and compare them. The findings show that IT investment has a positive and significant impact on firm efficiency in both Korea and China, but a weakly positive impact on firm growth in only Korea. Moreover, the size of the impact on efficiency (ROA) in China is significantly larger than that in Korea.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.83-89
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• 1999

Butterhead lettuce was grown hydroponically in a plant factory during summer season. To decrease the occurrence of tipburn and increase productivity, optimum cultivars, substrates, gully slope and height, and the amount of irrigation were evaluated in this experiment. Cultivars ‘Rex’ and ‘Flandria’ showed higher productivity with less tipburn as compared to the others in spite of lower growth rates and appeared to be suitable cultivars during summer season. Cocopeat showed high productivity due to superior physio-chemical characteristics. Appropriate gully slope which makes nutrient solution easy to flow was shown to be 1 to 2%. The amount of irrigation was appropriate at 2$\ell$/gully. Higher growth of the butterhead lettuce observed when the bed was at a lower position. Low bed was thought to be good for lettuce growth with proper humidity and average temperatures.

• KSBB Journal
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• v.30 no.6
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• pp.307-312
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• 2015

Transgenic rice cells using RAmy3D promoter can provide high productivity, and the production of recombinant protein is induced by sugar starvation. In this system, productivity was reduced during the scale-up processes. To ensure the influences of shear stress and oxygen transfer rate, working volume and mixing performances were investigated under various agitation speeds and working volumes. In addition, inoculation methods including suspended cells and filtered cells were compared. Working volumes and shaking speeds were 300, 450 mL and 80, 120 rpm, respectively. Hydrodynamic environment of each condition was measured numerically like mixing time and $k_La$. Good mixing performance and high shear stress were measured at high agitation speed and low volume. The highest level of hCTLA4Ig was 30.7 mg/L at 120 rpm, 300 mL. When conditioned medium was used for inoculation, increased cell growth was noticed during the day 0~4 and decreased slower than filtered cells. Compared with filtered cells, the maximum hCTLA4Ig level reached 37.8 mg/L at 120 rpm, 300 mL and lower protease activity level was observed. In conclusion mixing performance is critical factor for productivity and conditioned medium can have a positive effect on damaged cells caused by hydrodynamic shear stress.