• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.1000-1007
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• 2001

In an evacuated tube solar collector, the stable sealing of the heat pipe to the glass tube is important for the collector to use for a long period of time. The sealing of copper tube to the glass is quite difficult because of the large differences in the physical and chemical properties of the two materials. In this study, therefore, a proper copper oxide layer was induced to improve the chemical bonding of the two materials, and the oxidation state of copper and the interface between copper and glass were examined by XRD, SEM and EDS. Its bonding strength was also measured. Cu$_2$O was formed when the bare copper was heat-treated under 600$^{\circ}C$, while CuO oxide layer was formed above that temperature. The bonding state of CuO to the copper was very poor. The borate treatment of the copper, however, extend the stable forming of Cu$_2$O layer to 800$^{\circ}C$. Borosilicate glass tube was sealed to a copper tube by Housekeeper method only when the sealing part was covered with Cu$_2$O layer. The bonding strength at the interface was measured 354.4N, its thermal shock resistance was acceptable.

• The Journal of Advanced Prosthodontics
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• v.11 no.2
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• pp.105-111
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• 2019

PURPOSE. Limited data is available regarding the differences for possible microleakage problems and fitting accuracy of zirconia versus titanium abutments with various connection designs. The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the sealing capability and fitting accuracy of abutments. MATERIALS AND METHODS. A total of 42 abutments with different connection designs [internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)] and abutment materials [titanium (Ti) and zirconia (Zr)] were evaluated. The inner parts of implants were inoculated with $0.7{\mu}L$ of polymicrobial culture (P. gingivalis, T. forsythia, T. denticola and F. nucleatum) and connected with their respective abutments under sterile conditions. The penetration of bacteria into the surrounding media was assessed by the visual evaluation of turbidity at each time point and the number of colony forming units (CFUs) was counted. The marginal gap at the implant- abutment interface (IAI) was measured by scanning electron microscope. The data sets were statistically analyzed using Kruskal-Wallis followed by Mann-Whitney U tests with the Bonferroni-Holm correction (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the groups based on the results of leaked colonies (P<.05). The EH-Ti group characterized by an external hexagonal connection were less resistant to bacterial leakage than the groups EH-Zr, IT-Zr, IT-Ti, IC-Zr, and IC-Ti (P<.05). The marginal misfit (in ${\mu}m$) of the groups were in the range of 2.7-4.0 (IC-Zr), 1.8-5.3 (IC-Ti), 6.5-17.1 (IT-Zr), 5.4-12.0 (IT-Ti), 16.8-22.7 (EH-Zr), and 10.3-15.4 (EH-Ti). CONCLUSION. The sealing capability and marginal fit of abutments were affected by the type of abutment material and connection design.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.365-369
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• 2004

The purpose of this study was to evaluate the apical sealing ability of Super-EBA, MTA and Dyract-flow as retrofilling materials. Forty-eight extracted human teeth with straight and single root canal were used in this study. The root canals were prepared to a #40 apical canal size and obturated with gutter-percha. Apicoectomies were performed and root end cavities were prepared to a depth of 3mm using an ultrasonic device. The root end cavities were filled with Super-EBA, MTA or Dyract-flow. Leakage was measured using an electrochemical technique for 4 weeks. According to this study, the results were as follows. 1. Increasing leakage with time was observed in all groups. 2. No significant difference was noted among the 3 groups with time (p =0.216). 3. No significant difference was noted among the 3 groups when measured within the same time interval (p =0.814). The results of this study suggest that the sealing ability of Dyract-flow is equal to that of Super-EBA and MTA, and Dyract-flow may be an alternative to other materials for root-end filling.

• Journal of the Korean Wood Science and Technology
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• v.44 no.4
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• pp.600-606
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• 2016

Wood-based composite panels such as plywood, particleboard (PB), or medium density fiberboard (MDF) are mostly used in the lamination on their surface for the manufacturing of furniture, or interior building products, the concern on the formaldehyde emission (FE) from the surface laminated wood panels is increasingly attracting attentions from the public. Thus, this study was conducted to understand influence of surface laminating materials to the FE from PB and MDF with or without edge sealing, using 24-hour desiccator method. Both PB samples that had been laminated on their surface with low-pressure laminate (LPL) or polypropylene (PP) film and MDF that had been treated with poly(vinyl chloride) (PVC) or coating were tested for the FE with or without edge sealing. As expected, the FE of PB with the sealed edges decreased to 37.4% and 80.7% with the LPL and PP lamination, respectively. The surface laminated MDF with the sealed edges also showed a decrease in the emission up to 57.8% and 54.3%, with the PVC lamination and coating, respectively. However, the coated MDF samples showed 5.3% increase in the emission when their edges were not sealed, indicating a FE form the solvent used for coating. These results showed that the type of surface lamination materials on wood-based composite panels has a great impact on their resultant FE, indicating that the influence of surface laminating materials should be taken into consideration for the formaldehyde mission measurement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1349-1354
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• 2013

Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.6-12
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• 2018

Recently, The use of the curtain wall method is increasing in construction. The curtain wall construction is widely applied to the exterior wall of the building for shortening construction period and economical efficiency. However, the replacement of deterioration of the weather resistance and structural behavior of the sealing material connecting the curtain wall method and the glass frame is necessary for introduction of the stable curtain wall method and quality improvement in accordance with KS F 4910 standard. In this study, the elastic restoring force test was performed in the external environment. In this study, the deterioration of the sealant was evaluated for structural sealants. In Korea, studies on the variable displacement behavior of structural sealants are lacked. In this study, the reproduced results in laboratory conditions are compared with the deteriorating conditions exposed to the external environment, and they are reflected in the design of sealing materials in the future. According to the results of the study, it was confirmed that the existing structure sealant meets the quality standard of KS F 4910, but in the conditions performed in this study, adhesion failure of the specimen and cracking of the surface occurred. Especially, in the weather resistance test, it is necessary to evaluate the long-term durability performance of the structural sealant used in the curtain wall method by checking the insoluble state of all the test pieces. Therefore, in order to apply a conventional structural sealant to the site, it is necessary to introduce another durability performance evaluation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.139-139
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• 2005

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.05a
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• pp.32.2-32.2
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• 2006

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.116-116
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• 2002

• The Journal of the Korean dental association
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• v.16 no.12 s.115
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• pp.935-940
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• 1978

The purpose of this study was to evaluate the marginal sealing ability of 'Hi-Pol' Enamel Bond system. Using freshly extracted human teeth and 2% acquous methylene blue, the marginal leakage of dye in restorative materials such as 'Hi-Pol' Enamel Bond system, Hi-Pol, Adaptic, Nuva system, Epolite and Amalgam were investigated at 37℃ and under temperature cycling in range of 4℃-60℃. the results as follows; 1. All filling materials showed some degree of marginal penetration by 2% methylene blue dye. 2. 'Hi-Pol' Enamel Bond system revealed the least marginal penetration by 2% methylene blue as Nuva did at 37℃, but under temperature cycling in range of 4℃-60℃ it showed the greatest marginal penetration. 3. Hi-Pol restoration showed a tendency the similar to the other composite restoration. 4. Nuva system had the most effective marginal sealing ability either at 37℃ and under temperature cycling.