• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.74-74
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• 2018

Ti-6Al-4V alloys have been widely used as orthopedic materials because of their excellent corrosion resistance and mechanical properties. However, it does not bind directly to the bone, so it requires a surface modification. This problem can be solved by nanotube and micropore formation. Plasma electrolytic oxidation (PEO) treatment for micropore, which combines high-voltage spark and electrochemical oxidation, is a new way of forming a ceramic coating on light metals such as titanium and its alloys. This method has excellent reproducibility and can easily control the shape and size of the Ti alloy. In this study, formation of bioactive surface by PEO-treatment after $2^{nd}$ ATO technique of Ti-6Al-4V alloy was invesgated by various instrument. Nanotube oxide surface structure was formed on the surface by anodic oxidation treatment in 0.8 wt.% NaF and 1M $H_3PO_4$ electrolytes. After nanotube formation, nanotube layer was removed by ultrasonic cleaning. PEO-treatment was carried out at 280V for 3 minutes in the electrolytic solution containing the bioactive substance (Mg, Zn, Mn, Sr, and Si). The surface of Ti-6Al-4V alloy was observed by field emission scanning electron microscopy (FE-SEM, S-4800 Hitachi, Japan). An energy dispersive X-ray spectrometer (EDS, Inca program, Oxford, UK) was used to analyze the spectra of physiologically active Si, Mn, Mg, Zn, and Sr ions. The PEO film formed on the Ti-6Al-4V alloy surface was characterized using an X-ray diffractometer (TF-XRD, X'pert Philips, Netherlands). It is confirmed that bioactive ions play an essential role in the normal bone growth and metabolism of the human skeletal tissues.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.23-32
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• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air($50^{\circ}C$) and room temperanrre($25^{\circ}C$) drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.

• Journal of Korean society of Dental Hygiene
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• v.16 no.1
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• pp.11-18
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• 2016

Objectives: The purpose of the study was to compare the oral health related characteristics between a long-term patients and general population. Methods: A direct interview questionnaire was completed by 160 patients and 165 general people from January 16 to April 31, 2014. The questionnaire consisted of general characteristics of the subjects, subjective health status, oral health behaviors, and needs of oral health. The data were analyzed using SPSS 18.0 program. Results: The long-term patients reported that most of them were denture wearers(38.1%), and had oral disease symptoms(62.5%) and xerostomia(65.6%). Most of the long-term patients were ex-smoker(31.3%) and did not receive regular dental check-up(92.5%). They did not know tooth brushing method(31.3%) and brushed their teeth less than twice a day(47.5%). Those who used tooth brush for more than 6 months accounted for 47.5%. Most of them did not use auxiliary oral hygiene devices(85.6%). The patients answered that oral health is not important(6.9%), oral health education is not necessary(7.5%), and oral cleaning(26.3%) should be included in oral health education. Conclusions: The self-reported oral health status of the long-term patients much more serious than the general population. It is necessary to educate the continuing oral health management program for the long-term patients.

• Design & Manufacturing
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• v.12 no.1
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• pp.41-46
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• 2018

This study proves the causes of cylinder and piston jam by scratches which is the fatal problem of hydraulic breaker through the thermal analysis and thermal-structural coupled field analysis. The trouble from the scratch is a complex problem which can be caused by manufacturing process (this is an internal factor) and the users mistake or contamination in the hydraulic circuit (these are an external factor). Hence, it's not easy to investigate the causes, also hard to prevent the recurrence. In this reason, hydraulic breaker manufacturers are trying to improve the manufacturing process such as machining, heat treatment, grinding, cleaning, also to prevent the contamination in hydraulic circuit and to remove the remains. It's being managed thoroughly by manufacturers. This study shows the effect of the temperature rise by the frictional heat generated when the piston hits the tool on the hydraulic oil while the hydraulic breaker is operating, also the temperature distribution when it starts to affect main components of hydraulic breaker. The stress and the amount of deformation also could be found through thermal-structural coupled field analysis. It proved that the stress and deformation are proportionally increased according to the temperature rise in hit area, and it affects the cylinder and the viscosity of hydraulic oil inside the cylinder when it heats up beyond the certain temperature.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.672-678
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• 2017

In this study, municipal solid waste (MSW) has collected 3 times and physico-chemical analysis has done. Nitrous oxide emissions from MSW incineration plant were measured continuously by EPA Method 18 and it was compared with the emission by calculation using the emission factor. The $N_2O$ emission of MSW incineration plant was more than twice as large as the emission by calculation. It was found that the installation of abatement facilities in MSW incineration plant is effective in achieving the greenhouse reduction targets and it can be ensure economical efficiency through emission trading system.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.12 no.1
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• pp.43-64
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• 2001

The purpose of this study was to measure performance of university libraries, especially investigating the components of service quality and their relationship to the customer satisfaction. The result of the statistical analyses is summarized as follows： The result of 5 point scale study shows the following degree of satisfaction in 55 components： timeliness of circulation, processing of fine. location of library, usefulness of retrieval system, library user education, speed of retrieval. number of terminals, and cleaning. On the other hand, shows the following degree of dissatisfaction in 55 components： speed of civil petitions, hour for program use, result of civil petitions, fixing of library user education, speed of retrieval, method of public relation, waiting time for Internet use, and use of the other library materials. Also. customers’matters of weight and importance was availability. learning facilities, suitable collections, circulation, and system of retrieval.

• The Research Journal of the Costume Culture
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• v.17 no.2
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• pp.216-224
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• 2009

This study was accomplished to examine the dyeing property and functionality of both cotton and silk fabrics dyed with clove extract. The purpose of this study was to investigate the effects of dyeing property, antibiosis, and sun protection effectiveness for a clove. The study method used in this study was the experimental research to extract dyestuffs from a clove, to treat dyestuffs with a mordant, and then to measure dyeing colorfastness, antibiosis, and sun protection for dyed fabrics. As a result of the test for dyeing colorfastness, in the case of colorfastness to laundry, the degree of discoloration showed grade $1\sim4$ and the degree of pollution showed grade $4\sim5$. Colorfastness to perspiration for both cotton and silk fabrics dyed showed grade $1\sim2$ to $4\sim5$. Colorfastness to sunlight showed grade 2 to $4\sim5$. Colorfastness to rubbing showed grade $3\sim4$ to $4\sim5$. In the colorfastness to dry cleaning, the degree of discoloration showed grade $3\sim4$ and the degree of pollution showed grade $4\sim5$. As a result of the antibiosis test, for the Staphylococcus aureus, both cotton and silk showed the bacteria reduction rate of 99.9% even after five times laundry, and for the Escherichia coli, cotton fabrics showed the bacteria reduction rate of 99.9% only after one time laundry, but silk fabrics showed the bacteria reduction rate of 99.9% even after five times laundry. As a result of the test for sun protection effectiveness, dyed silk fabrics showed the result more excellent than dyed cotton fabrics.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.800-803
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• 2008

Road is one of the infrastructure facilities, on which lines include various information for guiding a smooth traffic flow. This line marking work is continually removed and re-marked during maintenance. However, some problems exist when the line marking work is conducted. Traditional methods of using grinders and torches have risk of repetitive skill, and workers are exposed directly to the hazardous situations. Moreover, even though the equipment has developed, the line removing work induces environmental contamination and pollution line on the road. Therefore, this study can become one of the eco-friendly cleaning technologies using dry ice blaster equipment, and the new development of equipment will improve method of pavement marking removal. Also, it can introduce innovative automation in construction.

• Asian Journal of Atmospheric Environment
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• v.7 no.1
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• pp.1-7
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• 2013

To establish the method for investigating the behavior of aerosol particles deposited on the leaf surface against fog water under natural conditions, scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analysis and wash water analysis by ion chromatography after the washing treatment were performed using leaves of white birch collected from low part of the tree crown and the top of the tree in Sapporo City, Hokkaido, northern Japan. Each of collected leaves was divided into two parts according to the treatment performed: leaf surface (adaxial side) was 1) untreated, and 2) washed with deionized water with a pipette. In untreated samples, many particles of various shapes, including soil particles and organic debris, were deposited on the surface. Particles containing S were found on the surface of samples collected from only low part of the tree crown. After the washing treatment, SEM-EDX analysis revealed that soil particles and particles containing S had been washed off with water, although some particles such as soil particles and organic debris still remained on the leaf surface. The major anion such as $SO{_4}^{2-}$ was detected in wash water of all samples, although the peak of S in X-ray spectra was not detected from samples collected at top of the tree. The combination of SEM-EDX analysis with wash water analysis indicated that $SO{_4}^{2-}$ was deposited on the leaf surface in dissolved state and/or in state of submicron particles. These results suggested that fog water could remove soil particles and particles containing S and $SO{_4}^{2-}$ from the leaf surfaces, but not all particles. There was no difference in sampling position in the tree crown. Our study suggested that combination with SEM-EDX analysis and wash water analysis would be effective for investigation of the behavior of particles on the leaf surface against fog water.

• Journal of Surface Science and Engineering
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• v.43 no.1
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• pp.17-24
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• 2010

In this study, surface characteristics of dental implant fixture with various manufacturing process have been researched using electrochemical methods. The dental implant fixture was selected with 5 steps by cleaning, surface treatment and sterilization with same size and screw structure; the 1st step-machined surface, 2nd step-cleaned by thinner and prosol solution, 3th step-surface treated by RBM (resorbable blasting media) method, 4th step-cleaned and dried, 5th step-sterilized by gamma-ray. The electrochemical behavior of dental implant fixture has been evaluated by using potentiostat (EG&G Co, 2273A) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The corrosion surface was observed using field-emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy (EDS). The step 5 sample showed the cleaner and rougher surface than step 3 sample. The step 5 sample of implant fixture treated by RBM and gamma sterilization showed the low corrosion current density compared to others. Especially, the step 3 sample of implant fixture treated by RBM was presented the lowest value of corrosion resistance and the highest value of corrosion current density. The step 3 sample showed the low value of polarization resistance compared to other samples. In conclusion, the implant fixture treated with RBM and gamma sterilization has the higher corrosion resistance, and corrosion resistance depends on the step of manufacturing process.