• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.47-54
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• 2008

Recently, application of ceramics has increased gradually due to excellent mechanical properties. Si3n4-BN ceramic which is one of ceramics is very hard and has superior resistance against volatile temperature and wear. However, extremely high hardness of the $Si_3N_4-BN$ ceramic makes conventional machining very difficult. Therefore, the use of machinable ceramic has been in a poor because of difficult industrial processes in spite of many advantages. And so new technology being called IED(In-process electrolytic dressing) was introduced to solve this problem. The aim of this study is to determine the machining characteristics in terms of pressurized weight to the workpiece and the influence with h-BN content using IED lapping system. Also, Acoustic Emission (AE) is used for the monitoring of surface characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.178-189
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• 1993

Engineering ceramics have some excellent properties as the material for the mechanical components. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper experiments are carried out to obtain the effect of "In-process dressing" to grind the Engineering ceramics with high efficiency. To save running time for dressing process and obtain restraint effect of diamond grain wear, "In-process dressing" system usint WA stick type honing stone is proposed. Representative High Strength Engineering ceramics A1$_{2}$O$_{3}$ and Si$_{3}$N$_{4}$are ground with diamond wheel. Also bending strengrh test is carried out to check upward tendancy of mecahnical properties as the result of machining defact restraint through the grinding maching method using "In-process dressing" process. Some results obtained in this study provide useful information to attain the high efficency grinding and the high mechanical properties of Engineering ceramics.rties of Engineering ceramics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.75-80
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• 2013

Single crystal sapphire being used in high technology industry is a brittle material with a high hardness and excellent physical properties. ELID(Electrolytic In-Process Dressing) grinding technology was applied to material removal machining process of single crystal sapphire wafer. Ultrasonic vibration which added to material using ultrasonic table was adopted to efficient ELID grinding of sapphire materials. The evaluation of the ground surface of single crystal sapphire wafer was carried out by means of surface measuring by using AFM(Atomic Force Microscope), surface roughness tester and optical microscope device. As the results of experiment, it was shown that more efficient grinding was conducted when using ultrasonic table. In case of using #170 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was superior to ELID ground specimen without ultrasonic table. However, In case of using #2000 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was inferior to ELID ground specimen without ultrasonic table.

• Pediatric Infection and Vaccine
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• v.16 no.2
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• pp.131-141
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• 2009

Purpose : In February 2007, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections occurred in two newborns in the neonatal unit of Sahmyook Seoul Hospital. We performed this study to investigate the characteristics of MRSA nasal carriage among neonatal unit staffs and the effective infection control measures. Methods : Nasal swab specimens were obtained from the neonatal unit staff for the presence of MRSA. MRSA-colonized staffs were offered decolonization therapy with oral trimethoprim-sulfamethoxazole or 2% mupirocin ointment. Every 2-4months after decolonizaton, repeat nasal swab specimens were obtained. Also, samples from the neonatal unit environment and room air were collected. Results : Successful decolonization was achieved in 92% of the cases in 2 weeks after decolonization therapy, but most of the staffs were recolonized after several months. The nature of antibiotic susceptibility was changed from multi-drugsusceptible to multi-drug-resistant. The most frequently contaminated objects were dressing carts, computer keyboards, bassinets and washbowls. In environmental cultures using the settle microbe count method, the colony counts were decreased significantly at the last study period compared with the first study period in the neonatal room, breastfeeding room, service room, and dressing room (P <0.05). Conclusion : Effective control of sustained MRSA transmission within an institution may require prompt identification, treatment, and monitoring of colonized and/or infected staffs. However, nasal decolonization therapy may induce multi-drugresistant MRSA infection and had no effect on decreasing the MRSA nasal carriage rate in our study. Other factors might be more important, such as improving staff education, increasing hand hygiene practices, and environmental sterilization for controlling MRSA infections.