• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1481-1490
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• 2005

Carbon-carbon single bond-forming reaction is the most useful and fundamental reaction in organic synthesis. Most of the basic carbon-carbon single bond-forming reactions, thus, developed in the past. In these respects, conceptually new C-C bond formation reaction can be highlighted. The Baylis-Hillman reaction was found at the early 1970’s. However, extensive studies on this highly potential reaction were started only before 15 years. This review has been written to shed more lights to the importance of Baylis-Hillman reaction. We have focused mainly on the reaction mechanism, conceptually related reactions, and chemical transformations of the Baylis-Hillman adducts.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.381-388
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• 1994

A new process which co-fires the low-firing-substrate and copper conductor was studied to achieve good bond strength and low sheet resistance of conductor. Cupric oxide is used as the precursor of conductive material in the new method and the firing atmosphere of the new process is changed sequently in air H2N2. The addition of cupric oxide and variations of firing atmosphere permited complete binder-burnout in comparison with the conventional method and contributed to the improvement of resistance and bonding behaviors. The potimum conditions of this experiment to obtain the satisfactory resistance and bond strength are as follows (binder-burnout temperature in air; 55$0^{\circ}C$, reducing temperature in H2; 40$0^{\circ}C$ for 30 min, ratio of copper and cupric oxide; 60:40~30:70 wt%). The bonding mechanism between the substrate and metal was explained by metal diffusion layer in the interface and the bond strength mainly depended on the stress caused by the difference of shrinkage and thermal expansion coefficient between the substrate and metal.

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.70-78
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• 1983

This paper discusses the application of Si-Borosilicate glass sealing to a new sealing method which utilizes a large electrostatic field to pormote bound formation at relatively low temperature. Bonding mechanism and the effect of bonding time bonding temperature glass thickness and surface roughness on the bond strength were investigated. Application of a de voltage across bonded specimen gradually produced a layer of glass adjacent silicon which was depleted of mobile ions. As a consequence a n increasingly larger fraction of the applied voltage appeared across the depleted region and very large electric field resulted This field accompanyed by large electrostatic force acted as driving force the of strong bond. And stronger bond was formed with increasing bonding time and temperature. A low temperature preoxidation is advantageous for the Si surface having a rougher surface finish that 1 microinch.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.251-260
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• 2011

In this study, the effect of natural jute fiber volume fraction on the bond characteristics of polyolefin based macro fiber in natural jute fiber reinforced cement composites, including bond strength, interface toughness, and microstructure analysis are presented. The experimental results on polyolefin based macro fiber pullout test of different conditions are reported. Natural jute fiber volume fractions ranging from 0.1% to 0.2% are used in the mix proportions. Pullout tests are conducted to measure the bond characteristics of polyolefin based macro fiber from natural jute fiber reinforced cement composites. Test results are found that the incorporation of natural jute fiber can effectively enhance the polyolefin based macro fiber-cement matrix interfacial properties. The bond strength and interface toughness between polyolefin based macro fiber and natural jute fiber reinforced cement composites increases with the volume fraction of natural jute fiber. The microstructural observation confirms the findings on the interface bond mechanism drawn from the fiber pullout test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.233-241
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• 2005

The paper is presented experimental study results on bond stress between profiled steel and concrete in Profiled SPC(Profiled Steel Plate Concrete) rectangular steel tubes through an experimental program in which 13 pull-out specimens were tested. Advantages and class of composite members and current problems of construction work are noted, past research of PSSC is described. An experimental study is described and evaluated. The bond capacity is interrelated with slip at the steel concrete interface. The factors influencing the mechanism of bond stress transfer were the cross section shape, length/diameter, diameter/thickness and environmental parameters (temperature, moisture). The results of experimental program indicated that the force transfer could be characterized into two regions The first region was governed by bond with no relative slip between the profiled steel and concrete. The second region occurs after the chemical debonding. Bond stress transfer in this region was governed by frictional resistance between profiled steel and concrete and cross section shapes. The important factors influencing the magnitude of frictional resistance are the profiled steel shapes, length/diameter and environmental parameters. (temperature, moisture)

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.809-815
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• 2011

An experimental investigations on the bond-slip properties of the steel and Glass Fiber Reinforced Polymer(GFRP) bars in engineered cementitious composite (ECC) with Polyvinyl Alcohol (PVA) fibers are presented. Total of 8 beam specimens prepared according to the Rilem procedures with 2% of PVA and PE fiber volume percentage and steel and GFRP reinforcements significantly changed the failure mechanism and slightly improved bond strength. The main objective of the tests was to evaluate the load versus displacement and load versus slip behaviors and the bond strength for the following parameters: concrete type (normal and fiber concrete) and bar diameter (10 and 13 mm). The study results showed that ordinary concrete and ECC specimens showed similar behavior for steel reinforced specimen. However, GFRP reinforced specimen showed different behavior that the steel specimen. The code analytical results showed more accuracy compared to the experimental results as expected in conservative code provisions. Based on the obtained results, it is safe to conclude that the new parameters need to be adopted to ensure safe usage of ECC for construction applications.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.17-24
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• 2003

One of the reasons for brittle failure in reinforced concrete structures subjected to severe earthquake is due to large local bond-slippage of bars resulting in fast bond degradation between reinforcing bars and concrete. This study aims to evaluate effects of bar deformation height on bond performance, specially, bond degradation under cyclic loading. Bond test specimens were constructed with machined bars with high relative rib areas. The degree of confinement by transverse bars is also another key parameters in this bond test. From test results, amounts of energy dissipation are calculated and compared for each parameter. Test results show that bond strength and stiffness drops significantly as cycles increases. The confinement and high relative rib area are effective to delay bond degradation, as the reduction of bond strength of cyclic loading compared to monotonic loading decreased for bars with large confinement and high relative rib areas. The energy dissipation also increases as the degree of confinement and relative rib area increases. However, tested bars with very high rib areas show that the bond may be damaged at relatively small slip because of high stiffness. The study will help to understand the bond degradation mechanism due to bar deformation height under cyclic loading and be useful to develop new deformed bars with high relative rib areas.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.441-448
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• 1999

The load distribution in a ground anchor is very complex because it involves three different materials(soil, grout, and steel), which sometimes act as composite sections (bonded length) or separately (unbounded length). Therefore it is very hard to understand load transfer mechanism on the anchor. In order to understand the load transfer, it is essential to consider the load distribution In the three different materials. On these purposes, full scale anchor test is planned on the geotechnical site at Sunkyunkwan University Prior to the test, modeling and analyses of the load transfer mechanism were performed on the data from the case histories.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.111-113
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• 1986

The axial alcohol in trans-3,3,5-trimethylcyclohexanol was oxidized more readily than the equatorial alcohol in cis-3,3,5-trimethylcyclohexanol by NBS in aqueous dioxane. On the contrary, the equatorial alcohol was preferentially oxidized to the axial one by 10% aqueous sodium hypochlorite in the presence of tetrabutylammonium hydrogen sulfate (TBHS). The specificity indicates the presence of two different mechanism. In acidic medium, the cleavage of C-H bond is rate determining step while the reactivity of the alcohol is important in the presence of TBHS. The mechanism in basic medium without TBHS will be discussed.

• Journal of Forest and Environmental Science
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• v.12 no.1
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• pp.45-56
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• 1996

Generally, it has been know that AKD develops sizing efficiency by forming the chemical bond with cellulose in neutral paper making. However, there have been many expriments in opposition to this theory. This study was carried out to find whether there is chemical bond between AKD and cellulose or not. Also, it was investigated that how much the reacted AKD forming chemical bond and the unreacted AKD contribute to sizing degree respectively if chemical bond presents, and what caused AKD sized paper to migrate under high temperature. Besides, this work experimented several factors having influences on AKD sizing in paper amking.