• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.314-321
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• 2005

Objectives. The purpose of this study was to compare the shade changes in wet and dry conditions of natural teeth using two different intra-oral colorimeters. Materials and methods. Twenty volunteer subjects have no restorations and fillings in the maxillary central incisors were involved in this clinical study. The color of tooth was measured by two different instruments that were a Shade $Scan^{TM}$ System and a VITA $Easyshade^{(R)}$, Five times consecutive measurements were done for each subject with both instruments. Groups of measurement are an initial wet condition as control, dry in 5 minutes, 15 seconds after re-wetting with saliva, re-wetting after 5minutes and re-wetting after 30 minutes. Using ShadeScan $System^{TM}$, tooth image was captured and converted to the mapping image of Vitapan 3D master. Three main shades were chosen from each subject and calculated the area in Global Lab Image software. Data were analyzed using paired T-Test and Wilcoxon Signed Ranked Test. Using VITA $Easyshade^{(R)}$, color differences($\Delta$E) between measurements were analyzed with one sample T-test. Results. Using ShadeScan $System^{TM}$, there were significant differences between control group and dry(P=.023), dry and re-wetting 15 seconds, 5 minutes, 30 minutes as well(P=.021, P=.017, P=.030) in comparison of primary shade. However, comparing three main shades, there was no significant difference between control and dry(P=.105). Using VITA $Easyshade^{(R)}$, color differences($\Delta$E) between control and dry, dry and re-wetting 30 minutes were statistically different(P=.002, P=.022). Conclusion. Primary shade could be changed in dry and wetting procedure in time, however there was no significant shade changes in overall.

• Restorative Dentistry and Endodontics
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• v.27 no.4
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• pp.389-393
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• 2002

The marginal integrity of the crown can be broken during endodontic access cavity preparation due to the vibration of burs. Therefore, the purpose of this study was to evaluate the effect of endodontic access cavity preparation on the marginal leakage of full veneer gold crowns. 24 intact molars were mounted in acrylic resin blocks and prepared for crowns by a restorative dentist and crowns were cast with gold alloy. 20 Crowns were cemented with glass ionomer cement and 2 crowns were not cemented for positive control. 200 thermo-cycles from 5$^{\circ}C$ to 5$0^{\circ}C$ with a travel time of 20s were completed. Then samples were randomly divided into 2 experimental groups of 9 each. Endodontic access preparation and zinc-oxide eugenol temporary fillings were done in Group 1. Teeth in Group 2 were not treated. Samples were coated with 2 layers of nail varnish and were immersed in 1% methylene blue dye for 20 hrs. Endodontic access was prepared in 2 samples, which were coated with nail varnish on all surfaces for negative control. After washing in running water gold crowns were cut with a #330 bur. Four buccolingual sections, 2 mm apart, were cut from the central section of each tooth and were examined and scored under the microscope for dye leakage. Score 1: leakage to the cervical 1/3 of the axial wall, Score 2: leakage to the middle 1/3 of the axial wall, Score 3: leakage to the coronal 1/3 of the axial wall, Score 4: leakage to the occlusal surface. The median value for Group 1 is 4 and for Group 2 is 2. The result of this study showed that samples in Group 1 leaked more than those in Group 2. This finding was significant(P<0.001).

• Journal of Korean society of Dental Hygiene
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• v.13 no.4
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• pp.543-552
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• 2013

Objectives : The aim of the study is to investigate job performance expectations according to duration of work and to specify the clinical practice of dental hygienists by career expectations. Methods : The subjects were 310 dental hygienists in Seoul and Incheon. They completed the self-reported questionnaires and 304 data were analyzed except incomplete 6 answers. Results : The tasks performed by dental hygienists were as follows ; SS crown restoration in pediatric dentistry accounted for 25.1%, orthodontics (42.1 %), plaque removal (71.4 %), temporary fillings (60.5%), and impression taking of abutments and bite registration (58.9%). In order to be a skillful dental hygienists, it took two to three years of clinical filed work. Conclusions : On the job training (OJT) is the most important in dental hygiene curricula. So it is necessary to develop the OJT performance skill.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.672-675
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• 2005

To imprint 70-nm wide line-patterns, we used a newly developed ultraviolet nanoimprint lithography (UV-NIL) process in which an elementwise patterned stamp (EPS), a large-area stamp, and pressurized air are used to imprint a wafer in a single step. For a single-step UV-NIL of a 4' wafer, we fabricated two identical $5'\times5'\times0.09'(W{\times}L{\times}H)$ quartz EPSs, except that one is with nanopatterns and the other without nanopatterns. Both of them consist of 16 small-area stamps, called elements, each of which is $10\;mm\;\times\;10\;mm$. UV-curable low-viscosity resin droplets were dispensed directly on each element of the EPSs. The volume and viscosity of each droplet are 3.7 nl and 7 cps. Droplets were dispensed in such a way that no air entrapment between elements and wafer occurs. When the droplets were fully pressed between ESP and wafer, some incompletely filled elements were observed because of the topology mismatch between EPS and wafer. To complete those incomplete fillings, pressurized air of 2 bar was applied to the bottom of the wafer for 2 min. Experimental results have shown that nanopatterns of the EPS were successfully transferred to the resin layer on the wafer.

• Korean Journal of Materials Research
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• v.4 no.1
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• pp.31-36
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• 1994

The bonding behavior of $SiO_{2}$ thin film and glass during VCR head fabrication was investigated, varying the surface roughness of substrate and the sputtering parameter. Insufficient fillings of grooves In the $SiO_{2}$ film with glass was postulated to give rise to the generation of bubble in the glass. The surface roughness of $SiO_{2}$ film was found to depend on that of substrate. The lower the deposition rate, the smoother the surface of film. The bubble free glass after bonding could be obtained using substrate polished with 0.05$\mu\textrm{m}$ $Al_2O_3$ powder under the sputtering condition of 10% oxygen pressure.

• Journal of Korean society of Dental Hygiene
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• v.12 no.2
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• pp.431-438
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• 2012

Objectives : The aim of this study was assessment of the variation of urinary mercury concentrations after removal of amalgam fillings in children. Methods : 10 elemental school children with amalgam filling tooth surfaces were took part in this study. One dentist recorded the number of amalgam filling surface, and general characteristics of subjects were surveyed by questionnaire. Each urine samples were collected before, immediately after and after 24 hours amalgam removal. The statistical analysis was performed using the SPSS 18.0. Results : The mean concentration urinary mercury immediately after amalgam removal was higher ($5.70{\pm}1.20{\mu}g/g$ creatinine) than before amalgam removal ($5.28{\pm}1.53{\mu}g/g$ creatinine). The mean concentration urinary mercury level whose have 1-10 amalgam removal surfaces was increased after amalgam removal compared with before. Conclusions : Mercury concentration in urine was influenced by amalgam removal.

• The Journal of Fisheries Business Administration
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• v.25 no.1
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• pp.1-17
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• 1994

Coastal economic activities usually generate externalities to other economic activities. The conflicts between coastal economic activities, especially land fillings and reclamations, and fisheries in coastal waters pose a typical one, which sometimes causes some social conflicts. In this regard, as the contents and requirements for rules and regulations on fisheries compensation may have important implications for solving such problems, important is to review rationales fur the formulas in calculating fisheries compensation. The purpose of this paper is to review the formulas for fisheries compensation from the economic view points, to highlight some problems and to suggest more appropriate formulas. It is found that the current formulas of fisheries compensation are not properly based on economic concepts and valuation techniques. Main problems are related, as followings, to the coefficient(0.8) employed in the formula, to fishermen's own wages and to current values of invested assets such as fishing boats and nets, etc.. First, it is not clear what the coefficient(0, 8) means. In Japan's case, the coefficient was assumed to reflect the opportunity cost of fishermen's own wages, but it was disappeared from the formula after the self-wage came to be included in totaling fishing cost. As our new formula will include the self-wage in fishing cost, the coefficient(0.8) should be excluded. Second, according to our formula, the current value of invested assets is added to total operating compensation, which will overestimate total compensation. Therefore, it is suggested that total present value of the assets to be invested during the business life should be deducted from total operating compensation. Third, as the self-wage will be included in total cost, opportunity cost for finding new jobs should be newly added to the formula. Finally, this paper also conducted a comparative case study considering above-mentioned factors. The case study showed that the current formulas overestimated total fisheries compensation.

• Korean journal of food and cookery science
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• v.30 no.2
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• pp.146-152
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• 2014

This study surveyed consumers' sensory liking ratings of 3 types of developed brown rice products (brown rice nut waffles, Kimchi and tuna rice ball, sweet red-bean paste rice ball) and analyzed the drivers for liking or disliking the brown rice products. Each brown rice product had a brown rice to brown rice powder ratio of either: 100:0; 80:20; or 50:50. Forty consumers evaluated the acceptance of brown rice products on a 9-point hedonic scale and gave comments regarding liking or disliking each product. The results of the preference investigation analysis showed subjectivity depending on the brown rice product and the respondents' genders and ages. For brown rice nut waffles was affected by gender, age, and brown rice powder mixing ratio (p < 0.05). The variables "liking the aroma"; "liking the delicate flavor"; "liking the chewiness"; "liking the moistness"; "liking the softness"; "liking the harmony"; "liking the aftertaste" and "overall acceptability" did not differ significantly with the Kimchi and tuna rice ball. For the sweet red-bean paste rice ball product, the rates of liking the chewiness, stickiness, moistness, and softness of the 0% brown rice powder mix were all higher (p < 0.05) than were the rates of liking those same qualities in the 50% brown rice powder mix. Among all brown rice products, there were high correlations between the overall acceptability, liking the saltiness, liking the aroma, and liking the harmony. A preference investigation analysis showed that the brown rice product fillings were key factors to the products' overall acceptability.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.2
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• pp.120-128
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• 2013

This paper presents the results of sloshing experiments having different fluids in model tanks with various density ratios. The experimental model consisting water and air at ambient, which has been commonly used, is not consistent in density ratio with that of an actual LNG cargo tank. Therefore, an advanced experimental scheme is developed to consider the same density ratio of LNG and NG by using a mixed gas of sulfur hexafluoride ($SF_6$) and nitrogen ($N_2$). For experimental observation, a two-dimensional model tank of 1/40 scale and a three-dimensional model tank of 1/50 scale have been manufactured and tested at various conditions. Two different fillings with various excitation frequencies under regular motions have been considered for the two-dimensional model tank, and three different filling levels under irregular motions have been imposed for the three-dimensional model tank. The density ratio between gas and liquid varies from the ratio of the ambient air and water to that of the actual LNG cargo container, and the different composition of gas is used for this variation. Based on the present experimental results, it is found that the decrease of sloshing pressure is predicted when the density ratio increases.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.249-261
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• 2012

Phlogopite-bearing orthopyroxenite occurs in Andong ultramafic complex in a planar body of about 1 meter thick, and consists mostly of coarse subhedral to euhedral orthopyroxene crystals. Minor minerals are clinopyroxene, phlogopite, and plagioclase with trace chromian spinel, pentlandite, apatite, and zircon. Clinopyroxene occurs as either exolution lamella or interstitial fillings with phlogopite and plagioclase. Electron microprobe analysis showed that orthopyroxenes are entatite, while clinopyroxenes are diopside with little chemical variation through samples. Hydrous alteration resulted in the formation of talc, amphibole, and serpentine from orthopyroxene, clinopyroxene, and plagioclase, respectively. The orthopyroxenite was probably formed by the fractional crystallization of the ultramafic magma. Radiogenic dating of phlogopite and zircon of the orthopyroxenite would reveal the age of the Andong ultramafic complex.