• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.20-25
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• 2015

Purpose: This study was evaluated the shade of feldspathic porcelain with various concentration of silver ion. Materials and Methods: The control group was conventional feldspathic porcelain with no silver ion, the experimental groups were the feldpathic porcelain with 5%, 10%, 20%, 30% silver ion. The number of specimens on the each group was 5. Commission Internationale de I'Eclairage (CIE) $L^*a^*b^*$ parameters were recorded twice for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). One-way Anova was used for statistical analysis. Results: L value was similar. a value was increasing and b value was decreasing with silver ion statistically significantly. ${\Delta}E$ was increasing according to silver ion significantly. Conclusion: The shade of feldspahtic porcelain was influenced by silver ion. Ag ion under 10% concentration is acceptable clinically.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.606-617
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• 2000

The purpose of this study was to measure the marginal fidelities and the fracture strength of IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$ ceramic crowns. After constructed of 12 experimental dies for each group, ceramic crowns were fabricated on the metal master dies prepared on the maxillary right premolar Marginal gaps were measured on the specimen between the margin of each crown and finish-ing line of the metal master die by using stereo-microscope($SZ-ST^{(R)}$ Olympus, Japan) and all specimens were cemented on the metal master die with Bistite $II^{(R)}$ (Tokuyama soda Co, LTD., Japan) resin cement. Finally marginal gaps were measured again. To measure of the fracture strength, buccal incline on the functional cusp of specimens were loaded until the catastrophic failure occurred by using the AGS-1000 $D^{(R)}$(Shimadzu, Japan). The result of marginal fidelities and fracture strength were statistically analyzed with the SPSS version 8.0 programs. The results of this study were as follows : 1. No significant difference was found in the mean marginal fidelities and fracture strength between the IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$. 2. In comparison of marginal fidelities between before and after cementation, there was significant difference(P<0.05). The IPS Empress 2 system was shown in this study that had good marginal fidelities and fracture strength compared to In-Ceram ceramics. Although this system was acceptable to clinical applications, the system still has to be considered long-term researches about marginal fidelities and fracture strength due to the lack of data about the clinical researches.

• Journal of Energy Engineering
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• v.15 no.3 s.47
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• pp.146-153
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• 2006

A performance test of the stainless steel based sintered metal filter was conducted on the low and intermediate level radioactive waste (LILW) vitrification process. The applicability of the metal filter was based on the test results as well. The baseline pressure drop of the metal filter was evaluated similar to the ceramic filter. During the test, when the flow rate of off-gas was $110Nm^{3}/h$, the total baseline pressure drop was shown as $92mmH_{2}O$. The total pressure drop was attributed to the filter media and the residual dust layer and the value of each was $25mmH_{2}O\;and\;67mmH_{2}O$ respectively. The SEM-EDS spectrum and micrograph of the metal filter specimen showed, no corrosion and no physical damage both at the skin membrane and at the support layer. And most of the baseline pressure drop was caused by the deposition of dust on the surface of the membrane. In conclusion, even though the filter exposure time was short at the test, the performance of the stainless steel based metal filter was acceptable for the treatment of LILW vitrification process.

• The Journal of the Korean dental association
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• v.48 no.9
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• pp.680-687
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• 2010

The purpose of this study was to compare post cementation efficacy according to the different adhesive systems and cement delivery methods. A total of 40 extracted human single-rooted premolar teeth were randomly divided in four groups according to the two luting agents of Unicem applicap (3M ESPE, St. Paul, MN, USA) or Variolink II (Ivoclar Vivadent, Liechtenstein) and cement delivery methods of direct cement application or lentulo spiral application. After restoration using glass?fiber posts, the samples were embedded in acrylic resin. Three sections of 2 mm thickness were prepared from each specimen, and the post in each section was subjected to a push-out test. The data were analysed statistically at significant level of 95%. The Unicem had significantly higher push-out bond strength than Variolink and the lentulo spiral application made higher bond strength (p<0.05). Adhesive failure between cement and dentin was predominant in all groups. The Unicem of self-etch system and cement delivery using lentulo spiral showed clinically acceptable and comparable bonding strength for the fiber post.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.5
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• pp.309-314
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• 2008

The toxicity of five species of puffer fish, Arothron firmamentum (Byeolbok), Lagocephalus gloveri (Heukmilbok), L. wheeleri (Eunmilbok), L. inermis (Minmilbok) and L. lunaris (Milbok), collected from fish markets in Korea, was determined using a mouse bioassay. In A. firmamentum, the proportion of toxic specimens containing >10 MU/g was 87.5% in the ovaries, and 10.0% in the skin; no toxicity was detected in the muscle, fin, liver, intestine and gallbladder using the mouse bioassay. The highest toxin levels were found to be 87 MU/g in the ovaries, and 13 MU/g in the skin. Toxic specimens containing >10 MU/g were not detected from samples taken from any of the organs in L. wheeleri and L. inermis. In L. gloveri, most specimens were found to be non-toxic, but toxin levels of 11-72 MU/g were detected from within the skin, fins, and intestines in one specimen. In L. lunaris, the proportion of toxic specimens was 50.0% in the ovaries, and 7.1% in the gallbladder; no toxicity was detected in the other organs by the mouse bioassay. The highest toxin levels were 75 MU/g in the ovaries, and 14 MU/g in the gallbladder. Therefore, the toxicities of edible muscle and skin in the five species of puffer fish marketed in Korea were found to be within acceptable levels for human consumption.

• Geotechnical Engineering
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• v.12 no.2
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• pp.9-18
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• 1996

The results of a series of triaxial compression tests on remolded normally consolidated clay are compared with the predictions .by the isotropic single -hardening constitutive model, which incorporates eleven parameters. The parameters can be determined from undrained triaxial compression tests on isotropically consolidated specimens of remolded clay. The model with the determined parameters is applied to predict the stress-strain and pore pressure behaviors for untrained triaxial compresion tests on anisotropically consolidated specimens. Also the model is utilized to predict the stress strain and voltmetric strain behavior for drained triaxial compression tests on both isotropic and anisotropic specimens. The predicted response agrees well with the measured behavior for undrained triaxial compression tests on not only isotropically but also anisotroically but also anisotropically consolidated specimens. The initial volumetric strain is, however, predicted to be less than the measured value from drained triaxial compression tests, while the predicted volumetric strain close to failure is greater than the measured value. Nevertheless, it may be stated generally that overall acceptable predictions are produced. Therefore, the results of this study indicate that the applicability of the model on prediction of the behavior of normally consolidated clay is achieved sufficiently.

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1577-1583
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• 2000

Objectives : Among the various types of minimally invasive spine surgeries, thoracoscopic surgery is becoming more widely accepted and increasingly utilized. This report delineates our clinical experience using thoracoscopy to resect herniated thoracic discs in 16 patients who suffered from myelopathy or intolerable radiculopathy. Patients and Methods : Between Mar. 1997 and Sep. 1999, 16 consecutive patients underwent thoracoscopic discectomy for treatment of herniated thoracic discs. There were 12 men and 4 women(mean age 43.5 years ; range 18-61 years). Eleven patients presented with myelopathic signs and symptoms from spinal cord compression and 5 patients had incapacitating thoracic radicular pain without myelopathy. The surgical level was varied between T3 and T12. The pathology of specimen were 11 hard discs and 5 soft discs herniations. Thoracoscopic techniques were performed with long narrow spine instruments and high speed drill through 3 or 4 ports under one lung ventilated general anesthesia. During the operation three patients were converted to open thoracotomy due to intolerable one lung ventilation, excessive bleeding and inadequate operation field. The mean operation time was 264min.(range : 100-420min.), and postoperative mean admission period was 11 days. Results : Clinical and neurological outcomes were good in all patients(mean follow-up period 20 months). Among the eleven myelopathic patients, 8 improved neurologically, and 3 stabilized. Among the five radiculopathic patients, 4 recovered completely and no patient had worsened. Postoperative complications were pleural effusion in one case, intercostal neuralgia in one, delayed hemopneumothorax in one, prolonged air leakage in one and pneumonia in one case. Conclusions : Thoracoscopic discectomy needs a steep learning curve to be familiar to anatomical space and handling of endoscopic instruments. However, it is technically feasible and can be effectively performed with acceptable results.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.5
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• pp.544-555
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• 2004

Statement of problem: Shade selection has traditionally been accomplished by visual examination, which is particularly relevant to the shade selection of anterior teeth, but the subjective nature of visual analysis can lead to errors in shade matching. Recently shade selection systems have been developed to provide a more objective and scientific approach to understanding and clarifying shade selection. Purpose : The purpose of this study was analysis of various shade analyzing equipment with the goal of providing a more objective shade selection. Materials and method: Visual shade matching system selection(Vita Lumin Vacuum shade guide, Vitapan 3D Master shade guide) and mechanical shade matching method($ShadeEye^{(R)}$-EX Chroma Meter, $Shadescan^{TM}$ System) used for this study. The shade guide tap specimens for 10 extracted maxillary anterior teeth were produced by selecting shades using each shade matching system. The accuracy of the selection of shades for the teeth and fabricated specimens were evaluated by analyzing the calculated shade difference(${\Delta}E^*$), using a spectrophotometer and calculating the output of value $L^*,\;a^*,\;b^*$. Results and conclusion: The results show that the average ${\{Delta}E^*$ value (difference of shade) of the shade tap specimens to the actual specimen decreased in the following order: Vita Lumin Vacuum Shade Guide(VL), $ShadeEye^{(R)}$-EX Chroma Meter(SE) Vitapan 3D Master Shade guide(V3), and $Shadescan^{TM}$ System(55) : and that there are significant statistical differences between the VL and SS (p<0.05). In the analysis of the ${\Delta}E^*$ (difference of shade) value,40% of the VL group was found to be less than 3.3 (limit value of shade tap specimens clinically acceptable), 60% in the V3 group, 50% in the SE group, and 80% in the SS group.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.3
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• pp.275-283
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• 2006

Statement of problem. There have been many studies about marginal discrepancy of single restorations made by various systems and materials. However most of the statistical inferences are not definite because of sample size, measurement number, measuring instruments, etc, and there have been few studies about the marginal fit of the Digident CAD/ CAM zirconia ceramic crowns. Purpose. The purpose of this study was to compare the marginal fit of the anterior single restorations made by using the Digident CAD / CAM zirconia ceramic crowns with metal-ceramic restorations and to obtain more accurate information by using a large enough sample size and by making sufficient measurements per specimen. Material and Methods. The crowns were made from one extracted maxillary central incisor pre-pared with a 1mm shoulder margin and $6^{\circ}$ taper walls by milling machine. The in vitro marginal discrepancies of the digident CAD / CAM zirconia ceramic crowns and control groups(metal ceramic crowns) were evaluated and compared. Twenty crowns per each system were fabricated. Measurements of a crown were recorded at 50 points that were randomly selected for marginal gap evaluation. Parametric statistical analysis was performed for the results. Conclusion. Within the limitations of this in vitro study, the following conclusions were drawn: 1. Mean gap dimensions and standard deviations at the marginal opening for maxillary incisal crowns were $88{\pm}10{\mu}m$ for the control (metal-ceramic crowns), $92{\pm}4{\mu}m$ for Digident CAD / CAM zirconia ceramic crowns. 2. Marginal gap between Digident CAD / CAM zirconia ceramic crowns and metal ceramic crowns did not show significant difference (P>.05). 3. The Digident CAD/ CAM zirconia ceramic crowns and metal ceramic crowns showed clinically acceptable marginal discrepancy.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.4
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• pp.657-664
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• 1996

The purpose of this study was to compare the dimensional stability, compression resistance, elastic recovery and surface hardness of elastomeric interocclusal recording materials. Five commonly used elastomeric interocclusal recording materials(Ramitec, Regisil, Blue-Mousse, Stat-Br, Coltoflax) were selected for this study. According to ADA specification No. 19, two types of specimen were fabricated. Cylinder type specimens were used to test compression resistance and elastic recovery and plate type specimens were used to evaluate dimensional stability and surface hardness. Paired t-test was applied to detect significance among the occlusal registration materials. The obtained results were as follows: 1. There were statistical difference in dimensional stability between the elastic interocclusal recording materials. The dimensional stability of silicone was higher than that of polyether tested(p<0.05). 2. Coltoflax was significantly less resistance to compression than the other elastic interocclusal recording materials(p<0.001). 3. The elastic recovery capacity of Blu-Mousse and Stat-Br is better than that of Coltoflax (p<0.01). 4. The surface hardness of Coltoflax was lower than that of Blu-Mousse and Stat-Br(p<0.05). 5. The percentage dimensional change of alll materials was acceptable according to the limid of 0.5% suggeted by ADA specificatin No. 19.