• 대한안전경영과학회지
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• 제4권2호
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• pp.113-122
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• 2002

The marketing environment of recent security business has been changed as goods and service have been changed variously. Under this condition, the security corporations have been trying to have good relationship with customers and to have high gains as well. But the management of the customers in the bond marketing is not enough. Then, this paper suggests some methods to promote the CRM at bond brokerage in order to make profits in the security corporation. First, the customers will know the earning rate of the bond that they have and also they can analysis the difference selling the bond and keeping it until the due date. The developed bond management system analyzes customers' preference from questionaire which is responded by customers. It also can make customers actively sell and buy the bond through recommendations corresponding with customers' preference. Moreover, this paper suggests the video conference consulting system for close relationship with corporation and customers. We have tested this bond management system and we expect that this system activates the buying and selling of the bond that non-experts can easily invest bonds and the security corporations can increase profit.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.113-116
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• 2006

In this study, new bond-slip model is proposed. The proposed bond-slip model which has bilinear ascending regions and exponential descending region by modifying the conventional bilinear bond-slip model has been verified. Then, result by finite element analyses using interface element implemented with bond-slip model compared well with those of existing experiment researches on bond-slip models. It is shown that bond strength and effective bond length predicted by the bond-slip model and finite element analysis is good agreement with those of pull tests.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.140-146
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• 2016

Using density functional Theory, we studied local structure of liquid ethylene glycol and 1,3-propanediol. For both liquid, making intramolecular hydrogen bonding is not preferred, because relative energy between with and without intramolecular hydrogen bond is only -1.95kcal/mol, which is far less than intermolecular hydrogen bonding energy, about -7.5kcal/mol. Also, hydrogen bond induce polarization of hydroxyl group and make $2^{nd}$ hydrogen bond more stronger. This effect was small in intramolecular hydrogen bond of ethylene glycol. When considering energy per hydrogen bond, making only one intermolecular hydrogen bond for ethylene glycol pair is energetically favored, while two intermolecular hydrogen bond can be formed in 1,3-propanediol pair.

• 대한치과기공학회지
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• 제7권1호
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• pp.19-25
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• 1985

In oder to compare and measure bond strength of ceramometal system with use of ceramco porcelain powder including SnO2 and uni metal, Rexillium III, Vera Bond as non precious alloys manufactured for porecelain-metal restorations. Total 24 test sample were constructed. All Test sample were measured with a Mitutoyo micrometer graduated to 0.01mm. It is as follows measured of thickness 3.3mm(metal : 1.1mm, porcelain: 2.2mm), width 12mm, length 30mm(porcelain 12mm x 12mm), Compared maximum bending stress test. The results obtained were as follows: 1. Bond strength of each metal with ceramco porcelain powder showed statistical significance.(P<0.05) 2. Vera Bond and uni metal, uni metal and Rexillium III revealed no statistical Significance.(P>0.05) Vera Bond and Rexillium III showed statistical significance.(P<0.05) 3. The order of maximum bending stress was Rexillium III, uni metal, vera Bond. The order of bond strength ratio making bending stress was Vera bond, uni metal, Rexillium III.

• Computers and Concrete
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• 제29권3호
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• pp.145-159
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• 2022

In this study, the extreme learning machine and deep learning models were devised to estimate the bond strength of corroded reinforcement in concrete. The six inputs and one output were used in this study. The compressive strength, concrete cover, bond length, steel type, diameter of steel bar, and corrosion level were selected as the input variables. The results of bond strength were used as the output variable. Moreover, the Analysis of variance (Anova) was used to find the effect of input variables on the bond strength of corroded reinforcement in concrete. The prediction results were compared to the experimental results and each other. The extreme learning machine and the deep learning models estimated the bond strength by 99.81% and 99.99% accuracy, respectively. This study found that the deep learning model can be estimated the bond strength of corroded reinforcement with higher accuracy than the extreme learning machine model. The Anova results found that the corrosion level was found to be the input variable that most affects the bond strength of corroded reinforcement in concrete.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.29-34
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• 2006

Elastic modulus, tensile and bond capacities are important factors for developing an effective reinforcing action of a flexural member as a reinforcing material for concrete structures. Reinforcement must have enough bond capacity to prevent the relative slip between concrete and reinforcement. This paper presents an experimental study to clarify the bond capacity of prestressed carbon fiber reinforced polymer(CFRP) rod manufactured by an automatic assembly robot. The bond characteristics of CFRP rods with different pitch of helical wrapping were analyzed experimentally. As the result, all types of CFRP rods show a high initial stiffness and good ductility. The mechanical properties of helical wrapping of the CFRP rods have an important effect on the bond of these rods to concrete after the bond stress reached the yield point. The stress-slip relationship analyzed from the pull-out test of embedded cables within concrete was linear up to maximum bond capacity. The deformation within the range of maximum force seems very low and was reached after approximately 1 mm. The average bond capacity of CF20, CF30 and CF40 was about 12.06 MPa, 12.68 MPa and 12.30 MPa, respectively. It was found that helical wrapping was sufficient to yield bond strengths comparable to that of steel bars.

• Restorative Dentistry and Endodontics
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• 제37권3호
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• pp.155-159
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• 2012

Objectives: To investigate the effect of dentin moisture degree and air-drying time on dentin-bond strength of two different one-step self-etching adhesive systems. Materials and Methods: Twenty-four human third molars were used for microtensile bond strength testing of G-Bond and Clearfil $S^3$ Bond. The dentin surface was either blot-dried or air-dried before applying these adhesive agents. After application of the adhesive agent, three different air drying times were evaluated: 1, 5, and 10 sec. Composite resin was build up to 4 mm thickness and light cured for 40 sec with 2 separate layers. Then the tooth was sectioned and trimmed to measure the microtensile bond strength using a universal testing machine. The measured bond strengths were analyzed with three-way ANOVA and regression analysis was done (p = 0.05). Results: All three factors, materials, dentin wetness and air drying time, showed significant effect on the microtensile bond strength. Clearfil $S^3$ Bond, dry dentin surface and 10 sec air drying time showed higher bond strength. Conclusions: Within the limitation of this experiment, air drying time after the application of the one-step self-etching adhesive agent was the most significant factor affecting the bond strength, followed by the material difference and dentin moisture before applying the adhesive agent.

• International Journal of Concrete Structures and Materials
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• 제1권1호
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• pp.37-43
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• 2007

This paper discusses the failure mode of reinforced concrete beams strengthened with composite materials based on six experimental set-ups to determine the FRP-to-concrete bond strength. Interfacial bond behavior between concrete and CFRP plates was discussed. Shear test were performed with different concrete compressive strengths (21 MPa and 28 MPa) and different bonding length (100 mm, 150 mm, 200 mm, and 250 mm). Shear test results indicate that the effective bond length (the bond length beyond which the ultimate load does not increase) was estimated as $196{\sim}204\;mm$ through linear regression analysis. Failure mode of specimens occurred due to debonding between concrete and CFRP plates. Maximum bond stress is calculated as about $3.0{\sim}3.3\;MPa$ from the relationships between bond stress and slip. Finally, the interfacial bond-slip model between CFRP plates and concrete, which is governed debonding failure, has been estimated from shear tests. Average bond stress was about $1.86{\sim}2.04\;MPa$, the volume of slip between CFRP plate and concrete was about $1.45{\sim}1.72\;mm$, and the fracture energy was found to be about $1.35{\sim}1.71\;N/mm$.

• Advances in concrete construction
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• 제10권2호
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• pp.113-125
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• 2020

This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

• 한국농공학회논문집
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• 제46권3호
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• pp.73-81
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• 2004

FRP reinforcing bars(rebars) are produced through a variety of manufacturing process includes pultrusion, and filament winding and braiding etc. Each manufacturing method produces a different surface condition of FRP rebar. The surface properties of FRP rebar is an important property for mechanical bond with concrete. Current methods of providing surface deformation to FRP rebars include helical wrapping, surfaces and coating and rib molding. The problem with the helical wrapping method is that it can not provide enough surface deformation for good bond and it can be easily sheard off from the FRP rebars. Sand coating and rib molding provide surface deformation only to the outer FRP skins. Therefore, FRP rebar has about 60% of bond strength of steel rebar. The main objective was to evaluate the bond properties of FRP rebar after environmental exposure. Five types of FRP rebar includes CFRP ISO, GFRP Aslan, AFRP Technora CFRP(Korea), and GFRP(Korea) rebars performed direct bond tests. Also, FRP rebar bond specimens were subjected to exposure conditions including alkaline solution, acid solution, salt solution and deionized water etc. According to bond test results, CFRP(Korea) and CFRP(Korea) rebars were found to have better bond strength with concrete than previous FRP rebars. Also, FRP(Korea) rebar had more than about 70% in bond strength of steel rebar.