• Journal of Periodontal and Implant Science
• /
• v.38 no.4
• /
• pp.699-708
• /
• 2008

Purpose: The aim of this study was to investigate the effect of tongue cleaner-equipped manual toothbrush on tooth cleanness, tongue cleanness and malodor index. Materials and methods: 504 subjects were included in this study. At 1st visit, basic information such as age, sex, smoking amount and alcohol consumption was recorded. Self assessment by individual subjects was performed regarding satisfaction to old toothbrush and toothbrushing habit. Tooth cleanness, tongue cleanness and malodor index was assessed by professional researcher. Tongue cleaner-equipped manual toothbrush was given to each subject with proper toothbrushing instruction. After 1 month passed, self assessment and researcher assessment regarding the same index were performed and analyzed statistically by chi-square test. Results: At 1st visit subjects seem to ignore tongue cleansing and showed poor tooth cleanness index, tongue cleanness index and malodor index, however the same subjects were motivated to clean their tongue and teeth and presented statistically improved distribution pattern in tooth cleanness index, tongue cleanness index and malodor index after using tongue cleaner-equipped manual toothbrush(p<0.01). Satisfaction to tongue cleaner-equipped manual toothbrush was 98%. Conclusion: Tongue cleaner-equipped manual toothbrush would be an effective tool for maintaining good oral hygiene through improving tooth and tongue cleanness and preventing malodor formation.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.10 no.3
• /
• pp.218-224
• /
• 2005

Surface modification of glutaraldehyde fixed bovine pericardium (GFBP) was success­fully carried out with hyaluronic acid (HA) derivatives. At first, HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional group into the carboxyl group of HA backbone. Then, GFBP was surface modified by grafting HA-ADH to the free aldehyde groups on the tissue and the subsequent HA-ADH hydrogel coating. HA-ADH hydrogels could be prepared through selective crosslinking at low pH between hydrazide groups of HA-ADH and crosslinkers containing succinimmidyl moieties with minimized protein denaturation. When HA­ADH hydrogels were prepared at low pH of 4.8 in the presence of erythropoietin (EPO) as a model protein, EPO release was continued up to $85\%$ of total amount of loaded EPO for 4 days. To the contrary, only $30\%$ of EPO was released from HA-ADH hydrogels prepared at pH=7.4, which might be due to the denaturation of EPO during the crosslinking reaction. Because the carboxyl groups on the glucuronic acid residues are recognition sites for HA degradation by hyaluronidase, the HA-ADH hydrogels degraded more slowly than HA hydrogels prepared by the crosslinking reaction of divinyl sulfone with hydroxyl groups of HA. Following a two-week subcutaneous implantation in osteopontin-null mice, clinically significant levels of calcification were observed for the positive controls without any surface modification. However, the calcification of surface modified GFBP with HA-ADH and HA-ADH hydrogels was drastically reduced by more than $85\%$ of the positive controls. The anti-calcification effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue after staining with Alizarin Red S for calcium, which followed the trend as observed with calcium quantification.

• Journal of Welding and Joining
• /
• v.14 no.6
• /
• pp.109-118
• /
• 1996

Al$_2$O$_3$-TiO$_2$powders of six different compositions were plasma-sprayed on Ti substrate. The spray powders and the spray coated layers were analysed and compared using SEM and X-RD. The elastic properties (specific elastic constant and damping coefficient) of the coated specimens were measured in order to select the optimum composition range of ceramics for use in a speaker diaphragm. A correlation between the microstructure and elastic properties was also investigated. When $Al_2$O$_3$powders with 0- 13% TiO$_2$were plasma sprayed, the coated layers were composed of metastable y-Al$_2$O$_3$with small amount of $\alpha$-Al$_2$O$_3$and the content of $\alpha$-Al$_2$O$_3$was increased with TiO$_2$content. Specific elastic constant was rapidly increased with 2 and 13% TiO$_2$addition to $Al_2$O$_3$. The internal damping was nearly unchanged with TiO$_2$content The specific elastic constant seemed to be dependent on the content of $\alpha$-Al$_2$O$_3$in the coated layer.

• Polymer(Korea)
• /
• v.30 no.4
• /
• pp.350-356
• /
• 2006

In order to investigate the effect of the composition of weather-resistant coatings on physical properties, three different weather-resistant coatings were prepared by varying the ratio of a mill-base silicone/acrylic resin and let-down silicone/acrylic resin in weight ratios of 2 : 8, 3 : 7, and 4 : 6. The physical properties and weather-resistance of the prepared coatings were tested. It was found that the thermal stability, salt spray exposure, and weather-resistance were improved with increasing the amount of silicone. The optimum mixing ratio of mill-base silicone/acrylic resin to the let-down silicone/acrylic resin was 2 : 8. The coating containing silicone component of 30 wt% was found to be suitable as high weather-resistant coatings.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.5 s.108
• /
• pp.423-429
• /
• 2006

This paper deals with research for development of electromagnetic wave absorbers in sheet type for mobile phones. By controlling the sendust ratio, the $Al(OH)_3$ coating, the thickness, the kind of binders, and the milling time, electromagnetic wave absorbers were prepared and examined. Central frequency shills toward lower 2.2 GHz, 1.29 GHz, 842 MHz with increasing thickness 1 mm, 2 mm, 3 mm of the absorber, and absorption ability controlled each 2.2 GHz to 1.91 GHz, 1.29 GHz to 801 MHz, 842 MH2 to 801 MHz adjust sendust amount from 80 wt% to 85 wt%. The absorption band of the electromagnetic wave absorber coated with $Al(OH)_3$ becomes larger than that of non-coated one. Sendust composite microwave absorbers mixed with CPE were prepared at $70^{\circ}C$ in temperature. The fabricated electromagnetic wave absorbers show a reflection coefficient 5.76 dB at 1.8 GHz in thickness of 0.85 mm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.129-134
• /
• 2018

Herein, we report the manufacture of high-performance, ambipolar organic field-effect transistors (OFETs) and complementary-like electronic circuitry based on a blended, polymeric, semiconducting film. Relatively high and well-balanced electron and hole mobilities were achieved by incorporating a small amount of ionic additives. The equivalent P-channel and N-channel properties of the ambipolar OFETs enabled the manufacture of complementary-like inverter circuits with a near-ideal switching point, high gain, and good noise margins, via a simple blanket spin-coating process with no additional patterning of each active P-type and N-type semiconductor layer.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.1
• /
• pp.160-164
• /
• 2008

In this paper, The $TiO_2$ paste was prepared by changing the ratio of $TiO_2$(Degussa, P-25), binder (A-9540) and solvent. The paste was coated on to aluminuim metal plate to investigate the photodegradation of IPA. The best efficiency was obtained with increasing $TiO_2$ content and decreasing binder content. MEK is preferred to ethanol in terms of efficiency and the lower amount of solvent enhanced the rate. We, however, found the increasing viscosity of the paste and cracking with the lower content of solvent(MEK). In conclusion, the optimum activity was obtained when the ratio of $TiO_2$, Organic binder(A-9540) and MEK was 1.75 : 0.25 : 10.

• Transactions of the KSME C: Technology and Education
• /
• v.1 no.1
• /
• pp.49-57
• /
• 2013

The dimensioning accidental loads have been selected through suitable quantitative risk assessment and generally utilized important factors for offshore facility design. The fire hazard can be quantified with dimensioning fire loads. The main purposes of fire protection are to maintain the functionality of safety systems within evacuation period and to prevent the escalation from initial fire to uncontrolled catastrophic fire. This paper introduces the applications and the design methods of active and passive fire protections as representative measures of fire protection of offshore facilities. The passive fire protection requires the high initial installation cost and much difficulty on the operation of facilities and their maintenance. The oil major clients have asked the design contractors of offshore facilities to optimize the amount of passive fire protection with relevant engineering technology recently.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.29 no.2
• /
• pp.76-82
• /
• 1997

In paper the evenness of planar distribution of mass in a small scale is called formation (orbetter:mass formation). Traditionally formation has been assessed visually, by looking the sheet of paper against transmitted light. Different kinds of optieal testers are being usd to obtain quantitative rankings htat would be independent of the observer but would well correspond to the visual assessment. However, various raw-material and process factors do influence light trans-mittance in paper and do impair the correspondence between basis weight and the optical formation measurement (or visual assessment). As the optical formation test methods do not incorporate an efficient calib ration routine, the formation of the sophisticated paper grades of today the is rather difficult to measure optically and may lead to erroneous results. It may be concluded that the optical measurement is not suitable for paper grades with high filler content. coating, heavy calendering or that are made of heavily beaten pulp, nordoes it apply for dyed or printed papers. For this reason, visual assessment and optical evaluation shoild be replaced with a measurement that gives reliable results independent on paper grode and manufacturing process. Formation measuremend based on beta radiation is suitable for all paper grades regardless to the material contents or process treatment. It is possible to measure even dyed or printed samples. Thonks to a sim ple and relioble calibration, the results are converted to real basis weight balues that remain reliable even with time. The only beta tester commercially available is the AMBERTEC Beta Formation Tester. Formation of paper does vary locally in the web. Typically there exists a formation profile, too similarly to other properties of paper. Therefore, formation should ？ ays be expressed as a mean of a sufficient amount of parallel determinations. All formation measurements should be calibrated against basis weight.

• Journal of Biosystems Engineering
• /
• v.35 no.4
• /
• pp.257-261
• /
• 2010

Surface energy is the principal factor of anti-condensation. High surface energy appears hydrophilic itself and low surface energy represents hydrophobic itself. The contact angle is widely being used for measurement of surface energy of materials, evaluation of coating performances, measurement of wettability, and so on. However, the existing contact angle measuring system is so expensive for purchasing and complicated, so it takes a lot of time and money to use. This study was conducted to develop the algorithm for evaluating hydrophilic performance through measuring the contact angle of water droplet automatically, and fabricate relatively simple measuring system using a low-cost monochrome camera and image processing. A constant amount of water was firstly allocated on a slide by a micropipette, and then the image of water droplet was captured by monochrome digital camera and sent to a computer. The image was binarized and then reduced noises by labeling. Finally, the contact angle of water droplet was computed by using three points (left, right, and top coordinates), simple linear mathematics, and trigonometric function. The experimental results demonstrated the accuracy and reproducibility of the developed system showing less deviations and deviation ratio.