• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.111-112
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• 2009

Diamond-like carbon (DLC) is a convenient term to indicate the compositions of the various forms of amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), hydrogenated amorphous carbon and tetrahedral amorphous carbon (a-C:H and ta-C:H). The a-C film with disordered graphitic ordering, such as soot, chars, glassy carbon, and evaporated a-C, is shown in the lower left hand corner. If the fraction of sp3 bonding reaches a high degree, such an a-C is denoted as tetrahedral amorphous carbon (ta-C), in order to distinguish it from sp2 a-C [2]. Two hydrocarbon polymers, that is, polyethylene (CH2)n and polyacetylene (CH)n, define the limits of the triangle in the right hand corner beyond which interconnecting C-C networks do not form, and only strait-chain molecules are formed. The DLC films, i.e. a-C, ta-C, a-C:H and ta-C:H, have some extreme properties similar to diamond, such as hardness, elastic modulus and chemical inertness. These films are great advantages for many applications. One of the most important applications of the carbon-based films is the coating for magnetic hard disk recording. The second successful application is wear protective and antireflective films for IR windows. The third application is wear protection of bearings and sliding friction parts. The fourth is precision gages for the automotive industry. Recently, exciting ongoing study [1] tries to deposit a carbon-based protective film on engine parts (e.g. engine cylinders and pistons) taking into account not only low friction and wear, but also self lubricating properties. Reduction of the oil consumption is expected. Currently, for an additional application field, the carbon-based films are extensively studied as excellent candidates for biocompatible films on biomedical implants. The carbon-based films consist of carbon, hydrogen and nitrogen, which are biologically harmless as well as the main elements of human body. Some in vitro and limited in vivo studies on the biological effects of carbon-based films have been studied [$2{\sim}5$].The carbon-based films have great potentials in many fields. However, a few technological issues for carbon-based film are still needed to be studied to improve the applicability. Aisenberg and Chabot [3] firstly prepared an amorphous carbon film on substrates remained at room temperature using a beam of carbon ions produced using argon plasma. Spencer et al. [4] had subsequently developed this field. Many deposition techniques for DLC films have been developed to increase the fraction of sp3 bonding in the films. The a-C films have been prepared by a variety of deposition methods such as ion plating, DC or RF sputtering, RF or DC plasma enhanced chemical vapor deposition (PECVD), electron cyclotron resonance chemical vapor deposition (ECR-CVD), ion implantation, ablation, pulsed laser deposition and cathodic arc deposition, from a variety of carbon target or gaseous sources materials [5]. Sputtering is the most common deposition method for a-C film. Deposited films by these plasma methods, such as plasma enhanced chemical vapor deposition (PECVD) [6], are ranged into the interior of the triangle. Application fields of DLC films investigated from papers. Many papers purposed to apply for tribology due to the carbon-based films of low friction and wear resistance. Figure 1 shows the percentage of DLC research interest for application field. The biggest portion is tribology field. It is occupied 57%. Second, biomedical field hold 14%. Nowadays, biomedical field is took notice in many countries and significantly increased the research papers. DLC films actually applied to many industries in 2005 as shown figure 2. The most applied fields are mold and machinery industries. It took over 50%. The automobile industry is more and more increase application parts. In the near future, automobile industry is expected a big market for DLC coating. Figure 1 Research interests of carbon-based filmsFigure 2 Demand ratio of DLC coating for industry in 2005. In this presentation, I will introduce a trend of carbon-based coating research and applications.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.261-270
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• 2013

Purpose: Adsorption properties of lysozyme and albumin according to physiochemical properties of commercial contact lens classified with the FDA categories and a contact lens fabricated in the laboratory were investigated. Methods: The contact lens were prepared using HEMA(2-hydroxyethyl methacrylate) and TRIM(3-(trimethoxysilyl) propyl methacrylate) in a cast mold. Artificial tears containing lysozyme and albumin were prepared. We measured the amounts of protein adsorbed on the each lenses with varying adsorbed time (48 hour) and the pH range (6, 6.8, 7.4, 8.2, 9) of artificial tear. Amount of the proteins absorbed on the contact lenses were measured by using HPLC. Results: Time to reach the equilibrium of protein adsorption for silicone hydrogel lens was taken longer than hydrogel lens. The amount of adsorbed both lysozyme and albumin at equilibrium were greater for the hydrogel lens than the silicone hydrogel lens, and larger for the ionic lens than the non-ionic lens. Lysozyme was more adsorbed on the higher water content of contact lens, whereas albumin was more adsorbed on the lower water content of contact lens. Only lysozyme was adsorbed on the Group IV hydrogel lens of ionic higher water content. The adsorption of protein on contact lens increased with pH of artificial tears as close to the isoelectric point of each protein. Conclusions: The adsorption amount of lysozyme is more affected by the ionic strength of the contact lens surface than the water content of contact lens. Albumin adsorption is more affected by water content than the ionic strength of the contact lens surface. For the adsorption of proteins on the silicone hydrogel lens, the pore size, determined both by the number of Si atoms and the chemical structure of the silicone-containing monomers, as well as the polarity of contact lens should be also considered.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.38-44
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• 2015

This study was conducted to investigate the effects of electrolyzed water (EW) and hot-air-drying with ultraviolet light (UV) to reduce coliform bacteria of Undaria pinnatifida (UP). The UP was washed in the order of 15% EW, tap water (TW), and distilled water (DW) under following conditions: 15% EW for 10 min (washing: 1 time), TW for 1 min, and DW for 10 min (washing: 5 times). Viable cells, coliform, and mold counts were at 10²-10³ CFU/g in untreated samples. After EW treatment, viable cells, coliform, and molds were not detected in whole samples or on the surface of UP. But, after hot-air-drying at 48°C for 48 h, the number of viable cells, coliform, and molds were 10¹-10⁵ CFU/g. After hot-air-drying at 48°C for 48 h with UV (12-48 h), viable cells, coliform, and molds were not detected in whole samples or on the surface of UP. In respect of color value, there were no significant changes. In sensory evaluation, the UP with hot-air-drying with UV (12 h) had the highest score in overall preference among UV treatment groups. These results suggest that the treatments at 15% EW for 10 min and hot-air-drying at 48°C for 48 h with UV (12 h) were effective to reduce coliform bacteria of the dried Undaria pinnatifida.

• Food Science of Animal Resources
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• v.29 no.3
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• pp.382-390
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• 2009

This study was carried out to determine the effects of tomato powder (TP) as nitrite (NT) on pork patties. The following treatments were made: 0.01% NT (Tl), 0.01% NT and 1.0% TP (T2), 0.5% TP (T3), 1.0% TP (T4), and 0.01% NT and 1.0% TP (T5) were in basal formula (C). The following observations were made: T5 displayed lower gumminess and adhesiveness values than those of C and T1 (p<0.05) on Day 1 of storage; the hardness and surface hardness of T3 and T4 were relatively lower and the surface hardness and gumminess of T3 were relatively higher than the others (p<0.05) on Day 21 of storage; Y4 had significantly lower TBARS values than the others during storage; VBN values of the tested groups were significantly lower than the control samples on Day 7 and 21 of storage; T3 and T4 samples displayed lower pH values (p<0.05) than the control samples on Day 21 of storage; T3, T4 and T5 revealed lower CIE $L^*$ and W than those of C and T1 during storage; T2 had the highest CIE $a^*$ (p<0.05); T4 had significantly higher CIE $b^*$ and chroma values than those of others; T3 and T4 had significantly lower total plate counts than the others; T1 had significantly lower yeast and mold and Staphylococcus sp. counts than the other groups'; and T1 and T2 displayed significantly higher color acceptability than the others.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.509-518
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• 2002

The purpose of this study was to evaluate the bonding of compomer to deciduous dentin which is known to have been developed to improve the weak properties of glass ionomer cement and composite resin. 120 sound primary molars were used for the shear bond strength test and another 24 for the scanning electron microscopic evaluation. Each material was ailed into polyethylene mold attached to exposed dentinal surface($3{\times}4mm$ in diameter) of sample blocks. Shearbond strength was measured using Universal testing machine and data were analyzed statistically with Oneway-ANOVA and Scheffe test. Scanning electron microscopic observation was performed in order to evaluate the pattern of distribution and penetration of resin tags and hybrid layer. Compomer groups(II-V) showed significantly higher bond strength values than glass ionomer group(I)(p<.05). Etching-compomer groups(III, V) showed the significantly higher bond strength than non-etching compomer groups(II, IV)(p<.05), but slightly lower values than composite resin group(VI) with no statistically significant difference(p>.05). No significantly different bond strength was found between compomer groups of different bonding system(p>.05). Scanning electron micrographs showed more irregular distribution of short and thin resin tags in non-etching compomer groups(II, IV) whereas the more regular and intimate distribution of long and thick tags in etching compomer groups(III, V) and composite resin group(VI). The evaluation of hybrid layer also showed more regular formation of thicker layer in etching compomer groups(III, V). Based on the results of present study, the use of compomer as an esthetic restorative material for primary molars might be justified.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.464-470
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• 2001

The purpose of this study was to evaluate the tensile strength of light-cured restorative posterior resin-based composites. Five commercially available light-cured composites(Denfil : DF, P60 : PS, Unifil S : US, Z100 : ZH, Z250 : ZT) were used. Rectangular tension test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. Specimens were subjected to the 5,000 thermal cycles between $5^{\circ}C$ and $55^{\circ}C$ and the immersion time in each bath was 15 second per cycle. Tensile testing was carried out with Instron at a crosshead speed of 0.5mm/min and fractured surface were observed with scanning electron microscope. The obtained results were summarized as follows; 1. The tensile strength of PS was highest. PS was significantly higher than DF, US and ZH(p<0.05) but in the case of ZT was similar to PS(p>0.05). 2. The tensile strength DF was lowest. DF was significantly lower than PS, US, ZH and ZT(p<0.05). 3. The tensile strength of US and ZH were significantly lower than PS and ZT(p<0.05). but were significantly higher than DF(p<0.05). The tensile strength of US and ZH were similar(p>0.05).

• Journal of Conservation Science
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• v.30 no.3
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• pp.263-275
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• 2014

It's shown how to proceed the study on Manufacturing techniques & Conservation to the Iron Pot from Cheonmachong Ancient Tomb(the 155th Tomb in Hwangnam-dong). In order to investigate manufacturing techniques of the Iron Pot, some parts of the relic were gathered. After mounting, polishing and etching on the relic, analyzing the metal microstructure was conducted. Also it's conducted a SEM-EDS analysis on the nonmetallic inclusion. White iron structure was observed in the metallurgical structure inspection, SEM-EDS analysis. It seems to be dried slowly at room temperature after casting, doesn't look as particular heat treatment to improve brittleness. It is estimated that it's as the handle seam side were verified about 3cm inch wide, 1.5 thick in center of body, so 2 separate half-completed products was cast with width-type mould. The manufacturing techniques Using white cast iron structure, width-type mould are observable to the Iron Pot excavated from Sikrichong Ancient Tomb & Hwangnamdaechong grand Ancient Tomb around those were constructed the same time. It's able to recognize that it's almost identical manufacturing techniques at that time. Conservation is generically following those are survey of pretreatment, foreign material removal, stabilization, restoration and color matching in the order. cleaning & drying were added to the process as occasion demands. The strengthening treatment were difficult with artifact's volume, low concentration Paraloid NAD-10 solution was spread two or three times with a brush, surface hardening also came up with 15wt% Paraloid NAD-10 solution after the conservation was complete. There were connection & restoration for the restoration to the damage after modeling forms that it's similar to damaged parts by using the Fiber Reinforced Plastic resins(POLYCOAT FH-245, mold laminated type). Throughout this research, capitalizing on accumulations of measurements about the production technique of Iron Pot in the time of the fifth and 6th centuries is no less important than the Iron artifact's conservation for a better study in the future.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.509-516
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• 2005

For the purpose of comparing the bond strengths of compomers to composite resin, composite Z250, and two polyacid modified composite resin, Dyract AP and F2000, were selected and investigated using universal testing machine for measuring the shear bond strengths. Additionally, the failure modes were examined by observing the fractured surfaces of each specimen. The following results were obtained. 1. The shear bond strength of Dyract AP to Z250 were higher than those of F2000, but there was no statistically significant difference between group 1 and group 3(p>0.05), and groups using fresh compomers showed higher bond strength than those using aged compomers(p<0.05). 2. After measuring the shear bond strength of each group, it was highest in group 5 and was lowest in group 9(p<0.05). 3. Although there was no statistically significant difference, groups treated with thermocycling showed lower bond strengths than those of non-thermocycling groups. 4. Overall compomer/composite resin failures were adhesive. Cohesive failures occurred mainly in groups using bonding agent. Based on these results, the application of a bonding agent on fresh polyacid-modified resin composite increases the bond strength between polyacid-modified resin composite and composite resin. Additionally, the surface of aged polyacid-modified resin composite has to be roughened mechanically and a bonding agent has to be used in combination with composite resin.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.263-268
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• 2006

Recently, self-etching adhesive system has been introduced to simplify the clinical bonding proce- dures. It is less acidic compared to the phosphoric acid, thus there is doubt whether this system has enough bond strength to enamel. The purpose of this study was to investigate the influence of additional etching on the adhesion of resin composite to enamel. Ninety extracted bovine permanent anterior teeth were used. The labial surfaces of the crown were ground with 600-grit abrasive paper under wet condition. The teeth were randomly divided into six groups of 15 teeth each. Clearfil SE $Bond^{\circledR},\;Adper^{TM}$ Prompt L-Pop and Tyrian $SPE^{TM}$ were used as self-etching primers. Each self-etching primers were applied in both enamel specimens with and without additional etching. For additional etching groups, enamel surface was pretreated with 32% phosphoric acid (UNI-ETCH, Bisco, Inc., Schaumburg, IL. USA). Hybrid resin composite Clearfil AP-X, (Kuraray Co., Ltd., Osaka, Japan) was packed into the mold and light-cured for 40 seconds. Twenty-four hours after storage, the specimens were tested in shear bond strength. The data for each group were subjected to independent t - test at p < 0.01 to make comparisons among the groups. In Clearfil SE $Bond^{\circledR}$, shear bond strength of additional etching group was higher than no additional etching group (p < 0.01). In $Adper^{TM}$ Prompt L-Pop and Tyrian SPE, there were no significant difference between additional etching and non-etching groups (p > 0.01). In conclusion, self-etching adhesive system with weak acid seems to have higher bond strength to enamel with additional etching, while self-etching adhesive system with strong acid seems not.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.189-197
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• 2023

Purpose. This study aimed to compare and evaluate the shear bond strength between various temporary prostheses resin blocks fabricated by subtractive and additive manufacturing methods bonded to self-curing reline resin. Materials and methods. The experimental groups were divided into 4 groups according to the manufacturing methods of the resin block specimens and each specimen was fabricated by subtractive manufacturing (SM), additive manufacturing stereolithography apparatus manufacturing (AMS), additive manufacturing digital light processing manufacturing (AMD) and conventional self-curing (CON). To bond the resin block specimens and self-curing resin, the reline resin was injected and polymerized into the same location of each resin block using a silicone mold. The shear bond strength was measured using a universal testing machine, and the surface of the adhesive interface was examined by scanning electron microscopy. To compare between groups, one-way ANOVA was done followed by Tukey post hoc test (α = 0.05). Results. The shear bond strength showed higher values in the order of CON, SM, AMS, and AMD group. There were significant differences between CON and AMS groups, as well as between CON and AMD groups. but there were no significant differences between CON and SM groups (P > .05). There were significant differences between SM and AMD groups, but there were no significant differences between SM and AMS groups. The AMS group was significantly different from the AMD group (P < .001). The most frequent failure mode was mixed failures in CON and AMS groups, and adhesive failures in SM and AMD groups. Conclusion. The shear bond strength of SM group showed lower but not significant bond strength compared to the CON group. The additive manufacturing method groups (AMS and AMD) showed significantly lower bond strength than the CON group, with the AMD group the lowest. There was also a significant difference between the AMD and SM group.