• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.70-79
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• 2006

many plumbing system are needed in the ceiling of the building as it becomes advanced more and more. This leads to make effective space between ceiling level and slab less. Also, piping system is not suitably arranged and operated if it is bent around the columns which they are a lot. But this system can be more effective if it passes through the columns directly. Most people think that those columns should not be damaged with such as holes. But actually this is existed in a hotel building in switzerland. This study is to fing out how much capacity the columns become damaged and low using model size of $20cm{\times}30cm$ rectangular section, and 160cm long, in the structural test. it's compressive strength is focused on $240kg/cm^{2}$ design strength, commonly used in korea. Compressive test for them was done at Hanyang University using UTM one thousand tone(1000t) capacity. Variable numbers for the study are one hole of dia 3cm with distance 20cm or 40cm, two holes of dia 3cm with 20cm and 40cm distance, one hole of dia 5cm with distance 20cm and 40cm, two holes of dia 5cm with 20cm and 40cm distance, me eccentric hole with 20cm and 40cm distance, Normal(without hole). two test specimens of each variable are made for the test. ED5H20 capacity was 16.7% decreased, compared to normal one. While ED5H40 distant 40cm from the end of column top showed 19.5% capacity decrease, compared to normal one. Strain of ED5H20 diameter 5cm, in distance of 20cm form the top of the column was less 5% than the one of diameter 3cm. Finally, conclusions are that in case of hole diameter 3cm, located at 20cm from the end of the column top, capacity was decreased down to 3, percent only compared to the same diameter hole with 20cm distant from the end of it.

• Journal of Periodontal and Implant Science
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• v.28 no.1
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• pp.87-102
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• 1998

The purpose of this stuffy was to assess and compare the osseous responses to implanted particles of porous synthetic HA (Interpore $200^{(R)}$, Interpore International, U.S.A.), resorbable natural bovine derived HA (Bio-$oss^{(R)}$, Gestlich Pharma, Switzerland) and calcium carbonate(Biocoral $450^{(R)}$, Inoteb, France) in bone defects. Four calvarial defects of 2.5mm diameter were created in earth of 16 Sprague-Dawley rats. The experimental materials were subsequently implanted hi three defects, leaving the fourth defect for control purpose. Four animals were earth sacrificed at 3 days, 1week, 2weeks and 4 weeks after surgery. The tissue response was evaluated under light microscope. Overall, histologic responses showed that all the particles were well tolerated and caused no aberrent tissue responses. There were difference in the amount of newly formed bone at the experimental sites and control site. There was more new bone formation associated with calcium carbonate site. In addition, the calcium carbonate site displayed multinucleated giant cells surrounding calcium carbonate particles after the 1st week, and osteoid tissue within the particle after the 2nd week. After 4 weeks, calcium carbonate particles were resorbed and replaced with new bone. The healing of the natural bovine derived HA site was similar to that of porous synthetic HA, except that new bone growth between the two particles have progressed more in the former site after the 2nd week. In the natural bovine derived HA site, the particle was surrounded by newly formed bone after the 4th week. After 4 weeks, the control site showed more mature bone than other sites. In conclusion, the grafted site were better in new bone formation than non-grafted sites. In particular the calcium Carbonate site showed the ability of osteoinduction and natural bovine denver HA showed osteoconduction in rat calvarial defects. This suggest that calcium carbonate and natural bovine derived HA could enhance the regenerative potential in periodontal defects.

• Journal of Periodontal and Implant Science
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• v.39 no.2
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• pp.149-156
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• 2009

Purpose: Deproteinized bovine bone substitutes are commonly used in dental regenerative surgery for treatment of alveolar defects. In this study, three different bovine bone minerals - OCS-B (NIBEC, Seoul, Korea), Bio-Oss (Geistlich - Pharma, Switzerland), Osteograft/N - 300 (OGN, Dentsply Friadent Ceramed. TN, USA) - were investigated to analyze the basic characteristics of commercially available bone substitutes. Methods: Their physicochemical properties were evaluated by scanning electron microscopy, energy dispersive X-ray spectrometer (EDS), surface area analysis, and Kjeldahl protein analysis. Cell proliferation and alkaline phosphatase (ALP) activity of human osteosarcoma cells on different bovine bone minerals were evaluated. Results: Three kinds of bone substitutes displayed different surface properties. Ca/P ratio of OCS - B shown to be lower than other two bovine bone minerals in EDS analysis. Bio-Oss had wider surface area and lower amount of residual protein than OCS - B and OGN. In addition Bio - Oss was proved to have lower cell proliferation and ALP activity due to lots of residual micro particles, compared with OCS - B and OGN. Conclusions: Based on the results of this study, three bovine bone minerals that produced by similar methods appear to have different property and characteristics. It is suggested that detailed studies and quality management is needed in operations for dental use and its biological effects on new bone formation.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.423-432
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• 2016

PURPOSE. The aim of this work is to evaluate different types of materials used for making implant abutments, by means of an in vitro study and a review of the literature, in order to identify the indications for a better choice of an implant-supported restoration in the anterior section. MATERIALS AND METHODS. 5 implant abutments were tested in a random order in the superior anterior maxilla of pig gingiva (n = 8): titanium dioxide (Nobel Biocare); zirconium dioxide, Standard BO shade (Nobel Biocare, Kloten, Switzerland); zirconium dioxide, Light BI shade (Nobel Biocare); zirconium dioxide, Intense A 3.5 shade (Nobel Biocare); and aluminium oxide. Each abutment was tested for 2 mm and 3 mm thickness. To determine color variation, VITA Easyshade Advance spectrophotometer (Vita Zahnfabrik, Bad Sackingen, Germany) was used. RESULTS. Results showed that the color variation induced by the abutment would be affected by the abutment material and gingival thickness, when the gingival thickness is 2 mm. All materials except zirconium dioxide (Standard shade) caused a visible change of color. Then, as the thickness of the gingiva increased to 3 mm, the color variation was attenuated in a significant manner and became invisible for all types of abutments, except those made of aluminium oxide. CONCLUSION. Zirconium dioxide is the material causing the lowest color variation at 2 mm and at 3 mm, whereas aluminium oxide causes the highest color variation no matter the thickness.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.293-302
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• 2007

I. Objectives The purpose of this study was to compare the shaping ability between the single length technique performed with Mtwo instruments (VDW, Munich, Germany) and the crown-down technique using K3 (SybronEndo, West Collins, CA, USA) and RaCe (FKG, La Chaux-de-Fonds, Switzerland) instruments. II. Materials & Methods Forty five curved canals in resin blocks were equally divided in to three groups. Group 1 (Mtwo) was instrumented used the full length of canal according to the manufacturer's instructions. The simulated canals was prepared to an instrument size of 35, 0.04 taper canal terminus. In group 2 (Race) and group 3 (K3) was instrumented in a crown-down manner and prepared to an instrument size of 30, 0.06 taper canal terminus. Pre- and post-instrumentation images were scanned and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 7 measuring points, beginning 1mm from the end point of preparation. Differenced of centering ratio were statistically analyzed using One-way ANOVA followed by Duncan's test. II. Results & Conclusion There was no significant difference on 1, 2, 3 and 7mm measuring point. At 4 and 5 measuring point, significant difference showed between the Mtow instruments and other two instruments. (p<0.05)

• Restorative Dentistry and Endodontics
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• v.28 no.4
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• pp.348-353
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• 2003

The purpose of present study was to evaluate the polymerization shrinkage stress and amount of linear shrinkage of composites and compomers for posterior restoration. For this purpose, linear polymerization shrinkage and polymerization stress were measured. For linear polymerization shrinklage and polymerization stress measurement, custom made Linometer (R&B, Daejon, Korea) and Stress measuring machine was used (R&B, Daejon, Korea). Compositers and compomers were evaluated: Dyract AP (Dentsply Detrey, Gumbh. German) Z100 (3M Dental Products, St. Paul. USA) Surefil (Dentsply Caulk, Milford, USA) Pyramid (Bisco, Schaumburg, USA) Synergy Compact (Coltene, Altstatten, Switzerland), Heliomolar (Vivadent/Ivoclar, Liechtenstein), and Compoglass (Vivadent Ivoclar/Liechtenstein) were used. 15 measurements were made for each material. Linear polymerization shrinkage or polymerization stress for each material was compared with one way ANOVA with Tukey at 95% levels of confidence. For linear shrinkage: Heliomolar, Surefil

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.881-892
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• 2016

Following the Fukushima accident and its extended station blackout, attention was brought to the importance of the spent fuel pools' (SFPs) behavior in case of a prolonged loss of the cooling system. Since then, many analytical works have been performed to estimate the timing of hypothetical fuel uncovery for various SFP types. Experimentally, however, little was done to investigate issues related to the formation of a flammable gas mixture, distribution, and stratification in the SFP building itself and to some extent assess the capability for the code to correctly predict it. This paper presents the main outcomes of the Experiments on Spent Fuel Pool (ESFP) project carried out under the auspices of Swissnuclear (Framework 2012-2013) in the PANDA facility at the Paul Scherrer Institut in Switzerland. It consists of an experimental investigation focused on hydrogen concentration build-up into a SFP building during a predefined scaled scenario for different venting positions. Tests follow a two-phase scenario. Initially steam is released to mimic the boiling of the pool followed by a helium/steam mixture release to simulate the deterioration of the oxidizing spent fuel. Results shows that while the SFP building would mainly be inerted by the presence of a high concentration of steam, the volume located below the level of the pool in adjacent rooms would maintain a high air content. The interface of the two-gas mixture presents the highest risk of flammability. Additionally, it was observed that the gas mixture could become stagnant leading locally to high hydrogen concentration while steam condenses. Overall, the experiments provide relevant information for the potentially hazardous gas distribution formed in the SFP building and hints on accident management and on eventual retrofitting measures to be implemented in the SFP building.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.847-858
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• 2016

An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ) and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI), Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1) a vertical channel modeling a pair of neighboring sub-channels; and (2) an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of $16{\times}64$ measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.371-380
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• 2000

The effect of fiber reinforcing materials on the fracture strength of composite resin was evaluated. Each ten composite resin bars reinforced by glassfiber[Fiber-Splint ML$^{(R)}$(Polydentia SA, Switzerland)], polyethylene fiber [Ribbond$^{(R)}$(Ribbond Inc., U.S.A.)] and polyaramid fiber[Kevlar$^{(R)}$(DuPont, U.S.A.)] were loaded under the 3-point compression technique. Another ten pure composite resin bars without reinforcement were used as a control group. Then mean fracture strength and standard deviation were calculated and a ANOVA and Scheffe test were used in statistics. The results were as follows: 1. Kevlar group showed the highest fracture strength as 175.5MPa (p<0.05). Fiber-Splint ML group showed the lowest fracture strength as 112.7MPa. 2. The mean value of fracture strength in Ribbond group was 136.4MPa, and that of unterated control group was 143.6MPa. No difference was found between the two groups. 3. Ribbond and Kevlar reinforcement groups showed a catastrophic failure, where complete separation of pieces occurs to a unseparated fracture pattern. The use of Kevlar reinforcement fibers with composite resin showed significant increase in the average load failure and the presence of the fibers did prevent the catastrophic crack propagation present in the unreinforced samples. The use of Ribbond reinforcement fibers with composite resin showed no significant increase in the average load failure. However, the presence of the fibers did prevent the catastrophic crack propagation. Because high strength of glassfiber are rapidly degraded on exposure to moisture and humidity. The use of Fiber-Splint ML reinforcement fibers with composite resin showed significant decrease in the average load failure and displayed catastrophic fractures.

• Restorative Dentistry and Endodontics
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• v.38 no.4
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• pp.222-226
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• 2013

Objectives: The aim of this study was to assess the influence of operator experience level on the lifespan of the WaveOne Primary file (Dentsply Maillefer, Ballaigues, Switzerland) in extracted teeth. Materials and Methods: Moderately curved canals of extracted maxillary and mandibular molars were randomly distributed into 2 groups: experienced and inexperienced operators. Ten files were allocated to each group (n = 10). Each canal was prepared until the working length was reached, and the same file was used to prepare additional canals until it separated. The number of canals prepared before file separation was recorded. The fragment length of each file was measured, and the location of the fragment in the canal was determined. Data were statistically analysed using the independent 2-sample t-test. Results: The 2 operators prepared a total of 324 moderately curved canals of maxillary and mandibular molars. There was no significant intergroup difference in the mean number of canals prepared (p = 0.27). The average lifespan of the WaveOne Primary file was 17.1 and 15.3 canals, and the longest lifespan was 25 and 20 canals, when used by experienced and inexperienced operators, respectively. There were no statistically significant intergroup differences in separated fragment length and location. Conclusions: Within the limitations of this study, operator experience level appears to have no effect on the lifespan of the WaveOne Primary file in preparation of moderately curved canals. Single teeth with multiple canals can be prepared safely even by a novice operator by using a single file.