• Polymer(Korea)
• /
• v.38 no.6
• /
• pp.815-819
• /
• 2014

Scaffolds of tissue engineering should be biocompatible and biodegradable for cell attachment, proliferation and differentiation. In the various scaffold fabrication, 3D printing technique can make the three dimensional scaffold with interconnected pores for cell ingrowth. Polycaprolactone (PCL) is biodegradable polyester with a low melting temperature and has been approved by the Food and Drug Administration (FDA). In this study, PCL scaffold was fabricated by 3D bioprinting system and surface modification of PCL scaffold was controlled by NaOH treatment. Morphological change and wetability of NaOH-treated scaffold were observed by SEM and contact angle measurement system. The remnant of PCL treated with NaOH was measured by ATR-FTIR. In vitro study of scaffolds was evaluated with WST-1 and ALP activity assay. NaOH treatment of PCL scaffolds increased surface roughness, hydrophilicity, cell proliferation and osteogenic differentiation. These results indicate that NaOH-treated PCL scaffold made by 3D bioprinting has tissue engineered potential for the development of biocompatible material.

• The Journal of Korean Academy of Prosthodontics
• /
• v.41 no.6
• /
• pp.720-731
• /
• 2003

Statement of problem. The importance of fixture design and surface treatment. Purpose. The clinical success of dental in plants is affected by many factors such like as degree of osseointegration, the effective load dispersion for the prostheses, and a lot of attempts have been made to overcome the difficulties. In this study, efforts were made to find the possibility of clinical acceptance of the dental implants of newly designed surface and resorbable blast media surcace. Materials and methods. In this study, two groups of custom-made, screw-shaped implants were prepared. The first with the consisting of Branemark clone design and the other with the new design. These implants were divided into four groups according to the kinds of surface treatment. Four implants($AVANA^{(R)}$, Osstem, Busan, Korea)of each group were installed in twenty rabbits. Group A was consisted of Branemark done implant left as machined, Group B with Branemark clone implants with RBM(Resorbable blast media) surface, Group C with newly designed implants left as machined and Group D with newly designed implants with RBM surface. One of the twenty rabbits died from inflammation and the observation was made for six weeks. Specimens from four groups were observed using scanning electron microscopy with 40, 100, 1000 magnification power and microsurface structures were measured by white-light scanning interferometry for three dimensional surface roughness measurements(Accura $2000^{(R)}$, Intek-Plus, Korea.). Removal torque was measured in 17 rabbits using digital torque gauge(MGT 12R, Mark-10 corp., NY, U.S.A.) immediately after the sacrifice and two rabbits were used for the histologic preparation(EXAKT $310^{(R)}$, Heraeus Kulzer, wehrheim, Germany) of specimens and observed under light microscope. Resonance frequency measurement($Osstell^{(R)}$) was taken with the 19 rabbits at the beginning of the implant fixation and immediately after the sacrifice. Results. Following results were taken from the experiment. 1. The surface of the RBM implants as seen with SEM had rough and irregular pattern with reticular formation compared to that of fumed specimens showing different surface topographies. 2. The newly designed implant with RBM surface had high removal torque value among four groups with no statistical significance. The average removal torque was $49.95{\pm}6.70Ncm$ in Group A, $51.15{\pm}4.40Ncm$ in Group B, $50.78{\pm}9.37Ncm$ in Group C, $51.09{\pm}4.69Ncm$ in Group D. 3. The RFA values were $70.8{\pm}4.3Hz$ in Group A, $71.8{\pm}3.1Hz$ in Group B, $70.9{\pm}2.5Hz$, $72.7{\pm}2.5Hz$ in Group D. Higher values were noted in the groups which had surface treatment compared to the untreated groups with no statistical significance. 4. The results from the histomorphometric evaluation showed a mean percentage of bone-to-implant contact of $45{\pm}0.5%$ in Group A, $55{\pm}3%$ in Group B, $49.5{\pm}0.5%$ in Group C, and $55{\pm}3%$ in Group D. Quite amount of newly formed bone were observed at the surface RBM-treated implants in bone marrow space.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.1
• /
• pp.18-25
• /
• 2022

Purpose: This study aimed to evaluate the color stability and antibacterial properties of the surface of polyethyl methacrylate (PEMA) resin with zirconia nanoparticles added. Materials and Methods: The control group was pure PEMA resin, and the experiment group was PEMA resin 15 mm in diameter and 2.5 mm in thickness disk-shaped specimens with 2, 4 and 8 w/v% of zirconia nanoparticles added, which were respectively divided into Group Z2, Group Z4, and Group Z8. After analyzing the surface roughness and color stability of the specimens, their antibacterial properties were evaluated using Porphyromonas gingivalis (P. gingivalis). The Statistical analysis was performed using when normality was met in the Shapiro-Wilk test, one-way ANOVA was used to test parameters, and Tukey's test was used as a post hoc test. When normality was not met, the Kruskal-Wallis test, a non-parametric test was used (P < 0.05). Results: The surface roughness measurement found that there was no significant difference between the experimental and control groups. The color stability evaluation showed that the Z2, Z4, and Z8 groups were within the color range of natural teeth. The adhesion of P. gingivalis was evaluated to be significantly reduced in Group Z2 compared to the control group (P < 0.05). In the Z2 group, Z4 group, and Z8 group, dead cells bacteria than the control group were observed. Conclusion: In conclusion, PEMA resin with zirconia nanoparticles added was within the range of natural teeth in color and reduced the adhesion of P. gingivalis.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.36 no.4
• /
• pp.253-258
• /
• 2010

Until now, evaluating the efficacy of brightening mainly depends on total reflective light measurement. For example, SHV (Saturation, Hue, Value), $L^*$ $a^*$ $b^*$ (CIELAB color space system) color space system was used and lightness and saturation changes were chosen as major parameters for evaluating brightening effect. However, those parameters were calculated from total reflective light on the skin and it is hard to evaluate perceptive efficacy such as luminescence, and glossy. In this research, we applied new method for estimating change of luminescence of skin by using 'Lumiscan' which uses polarized light for detecting surface and inside reflective light independently. We also tested 15 different parameters for finding correlations between luminescence and those parameters. As a results, our 2 different brightening products showed 5 ~ 9 % increase of luminescence at 4 and 8 weeks. And we also found that skin roughness (-28 %), melanin index (-17 %), redness (-7 %), hydration (15 %), and lightness (6 %) were related to luminescence of skin.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.47 no.2
• /
• pp.15-20
• /
• 2010

In this study, AZO (Al: 3 wt%) thin films have been prepared on PES Plastic substrates at various working pressure (5~20 mTorr), $O_2$ gas flow rate(0~3%) and the fixed substrate temperature of 200 f by using the RF magnetron sputtering and their optical and electrical properties have been studied. The XRD measurement shows that AZO thin films exhibit c-axis preferred orientation. From the results of AFM measurements, it is known that the lowest surface roughness (3.49 nm) is obtained for the AZO thin film fabricated at 5 mTorr of working pressure and 3% of $O_2$ gas flow rate. The optical transmittance of AZO thin films is measured as 80% in the visible region. We observe that the energy band gap of AZO thin films increases with decreasing the working pressure and the $O_2$ gas flow rate. This phenomenon is due to the Burstein-Moss effect. Hall measurement shows that the maximum carrier concentration ($2.63\;{\times}\;10^{20}\;cm^{-3}$) and the minimum resistivity ($4.35\;{\times}\;10^{-3}\;{\Omega}cm$) are obtained for the AZO thin film fabricated at 5mTorr of working pressure and 0% of $O_2$ gas flow rate.

• Journal of Biomedical Engineering Research
• /
• v.44 no.6
• /
• pp.404-413
• /
• 2023

In this research, we studied the development of a SUS304 microneedle array based on microfabrication technology and the applicability of Parylene-C thin film, a medical polymer material. First of all, four materials commonly used in the field of medical engineering (SUS304, Ti, PMMA, and PEEK) were selected and a 5 ㎛ Parylene-C thin film was deposited. The applicability of Parylene-C coating to each material was confirmed through SEM analysis, contact angle measurement, surface roughness(Ra) measurement, and adhesion test according to ASTM standards for each specimen. Parylene-C thin film was deposited based on chemical vapor deposition (CVD), and a 5 ㎛ Parylene-C deposition process was established through trial and error. Through characteristic experiments to confirm the applicability of Parylene-C, SUS304 material, which is the easiest to apply Parylene-C coating without pretreatment was selected to develop a microneedle array based on CNC micromachining technology. The CNC micromachining process was divided into a total of 5 steps, and a microneedle array consisting of 19 needles with an inner diameter of 200 ㎛, an outer diameter of 400 ㎛, and a height of 1.4 mm was designed and manufactured. Finally, a 5 ㎛ Parylene-C coated microneedle array was developed, which presented future research directions in the field of microneedle-based drug delivery systems.

• Journal of Conservation Science
• /
• v.27 no.3
• /
• pp.333-344
• /
• 2011

Cleaning of foreign matter and corrosion products on surface among conservation treatment of iron artifacts is an important part for looking up a original form. The sand blaster is the most popular equipment when it removes the foreign matter and corrosion products on iron artifacts surface. Current foreign matter and corrosion products equipment, which mostly uses, is sand blaster. Glass dust which sprayed from sand blaster is harmful and causing environmental pollution. In order to solve these problems, we investigated the $CO_2$ snow cleaning that use a eco-friendly equipment to apply for cleaning foreign matter and corrosion products on surface of iron artifacts. It examined by using sand blaster and $CO_2$ snow cleaning to aged steel coupon and iron artifacts. In case of aged steel coupon, the result showed that the sand blaster and $CO_2$ snow cleaning methods were similar to the degrees of cleaning foreign matter and corrosion products, through surface roughness, color measurement and SEM. $CO_2$ snow cleaning applied to aged steel coupons weren't worn out the surface in comparison with sand blaster by SEM. When applied to the iron artifacts, power nozzle of the $CO_2$ snow cleaning was an excellent cleaning effect that surface wern't worn out in comparison with sand blaster. And, it showed that internal structure change of metal was no found before and after cleaning by X-ray radiography. Consequently, we confirmed that cleaning of the sand blaster and power nozzle of $CO_2$ snow cleaning were similar to the effect. But, it's very careful to use this method because of high outlet pressure of power nozzle for applying to the iron artifacts. As a result of experiments, it could be found that the cleaning methods should be selected depending on internal state of the artifacts.

• Journal of the Korean Vacuum Society
• /
• v.21 no.6
• /
• pp.333-341
• /
• 2012

Indium Tin Oxide (ITO) thin films were prepared by RF magnetron sputtering with different flow rates of $O_2$ gas from 0 to 12 sccm. Electrical and optical properties of these films were characterized and analyzed. ITO deposited on soda lime glass and RF power was 2 kW, frequency was 13.56 MHz, and working pressure was $1.0{\times}10^{-3}$ Torr, Ar gas was fixed at 1,000 sccm. The transmittance was measured at 300~1,100 nm ranges by using Photovoltaic analysis system. Electrical properties were measured by Hall measurement system. ITO thin films surface were measured by Scanning electron microscope. Atomic force microscope surface roughness scan for ITO thin films. ITO thin films secondary electron emission coefficient(${\gamma}$) was measured by ${\gamma}$-Focused ion beam. The resistivity is about $2.4{\times}10^{-4}{\Omega}{\cdot}cm$ and the weighted average transmittance is about 84.93% at 3 sccm oxygen flow rate. Also, we investigated Work-function of ITO thin films by using Auger neutralization mechanism according to secondary electron emission coefficient(${\gamma}$) values. We confirmed secondary electron emission peak at 3 sccm oxygen flow rate.

• Korean Journal of Materials Research
• /
• v.10 no.9
• /
• pp.601-606
• /
• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.9
• /
• pp.3815-3821
• /
• 2012

The LCD frame is an important part which supports the BLU of medium/large sized TFT-LCD. To produce it efficiently, it is necessary to achieve the molding process improvement from 1 cavity to 2 cavity system. Because 2 cavity mold is compact and its hot-runner zone is broadened, it is difficult to control the temperature on the mold. In this study, injection molding analysis on the frame in 2 cavity process with FEA(Finite Element Analysis) software is carried out to estimate its quality. The calculated injection molding pressures and maximum deflection in 1 and 2 cavity processes are 41.13 MPa and 1.62 mm, 40.49 MPa and 1.66 mm respectively. The measured maximum flexure load and surface roughness of the left and right frame of 2 cavities are 209 N and 0.08 ${\mu}m$, 193 N and 0.10 ${\mu}m$ while those in 1 cavity are 140 N and 0.13 ${\mu}m$. Thermal image shows that the maximum standard deviation of the temperature on left and right side of 2 cavity mold is $1.23^{\circ}C$. The simulation and measurement results show that the quality of the frame in 2 cavity injection molding process as a whole is not worse than that of 1 cavity system. But maximum flexure loads of the frame in 2 cavity process are far greater than that in 1 cavity process.