• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.374-375
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• 2006

The purpose of this paper is to investigate the propriety of biodegradable polymer pad in spite of exchanging from existing polyurethane pad used in CMP(Chemical Mechanical Planarization). Poli 400 of G&P Technology for CMP and Ellipsometer of Rudolph AutoEL-III for measurement were used in this experiment. From this experiment, it is proven that the biodegradable polymer pad is sufficiently suitable in CMP process. Therefore, it is expected that, by using the biodegrable pad CMP manufacturing process, and will be decreased. Especially, wafer scratch can be decreased.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.292-294
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• 2006

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.225-227
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• 2006

As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-alloyed steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-alloyed steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-alloyed steel becomes quite expensive. Therefore, in order to replace Mn-alloyed steel, we performed build-up welding using CH-90 and investigated regarding to wear characteristics of build-up weld metal.

• The korean journal of orthodontics
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• v.5 no.1
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• pp.25-31
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• 1975

A study of the effects of multibanded orthodontic appliances on the oral lactobacilli was conducted on 41 multibanded group and 41 caries free group. The following conclusions were obtained. 1. In multibanded group, the average count of lactobacilli per milli-liter of saliva showed about 219,300 in male and 254,100 in female. In caries free group, the mean count of lactobacilli per milli-liter of saliva showed about 66,700 in male and 68,500 in female, Therefore, the average of lactobacilli in multibanded group was much higher than that of the caries free group in both sexes. 2. The average of all the types of lactobacilli colonies (Disk-type, Bell-type, Y-type) in multibanded group was much more than that of caries free group. 3. Multibanded orthodontic appliances were found to sufficiently alter oral environment to significantly affect disk-types and total counts in both sexes and bell-type in female, at $1\%$ level of confidence. But changes in bell-type and y-type, in male, were considered to be significant at $5\%$ level of confidence.

• Journal of Oral Medicine and Pain
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• v.6 no.1
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• pp.83-90
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• 1981

This study was undertaken to study the changes of epithelium of oral mucosa caused by diabetic disease in terms of keratinization and morphology of epithelial cells of oral mucasa, and to diagnose the oral diseases caused by systemic origns in terms of oral exfoliative cytology as a diagnostic tool. The author has studied the changes of epithelial cells on the cheek mucosa and upper antirior gingiva of 20 adult diabetic patients by Oral Exfoliative Cytology. And 50 healthy adults were selected as control group. The cytologic smears were stained by Papanicolaou method. The results were as follows : 1. In diabetic patient's cheek mucosa, Yellow staining cells were reveald as 11.8%, which was higher than the control group(4.2%). 2. In diabetic patients' upper anterior gingiva, Yellow staining cells were reaveale as 12.4%, which was lower than the control group(68.2%) 3. The changes of nucleus and cytoplasmic changes were not significantly different in diabetic patients and control group.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.998-1002
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• 2003

This paper investigates the characteristics of stiffness and load in the thrust bearing of spindle which could be changeable according to the groove shape of inlet, in order to design a high-stiffness air bearing by selecting a optimal groove shape. In experiments, dead weight and displacement sensor are used to measure the load carrying capacity and the stiffness respectively. Various shapes and different depth of groove of self-restrictor are used as experimental conditions. Comparative study between the theoretical value and the practical one by measuring the value of stiffness and load of the thrust bearing is performed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.45-48
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• 2001

SL(Stereolithogrphy) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. This effect causes excessive surface roughness and requires additional postprocess finishing such as abrasive basting which is detrimental to part geometry and time consuming. Hence paraffin coating and grinding postprocess is proposed to raise the surface quality of SL part. The paraffin which has suitable properties for the proposed postprocess is coated all over the part surface. By grinding the thin layer of coated on the SL part only, the surface roughness can be improved without any damage on the part. From the experimental result, It is verified as very practical for die casting with silicon rubber mold.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.137-140
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• 1997

In general, stereolithography parts is not suitable for master pattern. Because of its bad surface roughness. Therefore, To reduce roughness it requires post-process that is depending on user skill and takes long time to do. This study aims to develop an expert system which can select an optimal build orientation, reduce roughness and shorten post-processing time. Genetic Algorithm was introduced for optimization. A simplified computation model was developed for real-time response. For accurate roughness estimation, mterpolation of experimental data was implemented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.165-166
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1257-1260
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• 2003

Rapid Prototyping technology has many advantages such as Rapid Tooling. However, Using the RT technique is limited by the poor surface quality of the RP part. Thus, additional post-machining is required for improving the surface roughness by the sanding, grinding and polishing etc. But, these traditional finishing techniques are time and labor cost consuming. Hence, improving and formulation the finishing technique is inevitably necessary for the RF part. A new post-machining methodology for RP part is presented by the SLS part is used for automobile components in this research. Also, a web based interface tool that user requirements are rapidly ordered for post-machining RP part is developed.