• Journal of the Korean Society of Industry Convergence
• /
• v.10 no.4
• /
• pp.207-211
• /
• 2007

The durable lifetime of RC structures is shortened by various reasons, which are the generation of cracks in construction and service term, the exterior deterioration according to climatic condition, the surface damage due to chloride attack and the corrosion of reinforced bars. The durability of concrete structures is nevertheless able to be increased by the method and the material of reinforcement and repair. The epoxy resin is widely used for reinforment and repair of concrete because of the superiority in mechanical property, adhesive property, abrasion resistance, impact resistance and chemical resistance. The epoxy cement mortar with hardening agent has a lot of disadvantages that are troublesome mixing work, weakened weatherability and high cost for hardening agent. In this study, the mix proportion of mortar is presented just only with epoxy resin and some admixtures, and the test result of mortar without hardening agent shows the higher strength than the mortar with hardening agent. In the mix proportion, the weight of epoxy resin must be less than 15% of the unit weight of cement, and 10% of unit weight of cement is adequate for the weight of admixtures.

• Structural Monitoring and Maintenance
• /
• v.7 no.3
• /
• pp.233-259
• /
• 2020

Using bonded fiber-reinforced polymer laminates for strengthening wooden structural members has been shown to be an effective and economical method. In this research, properties of suitable composite materials (sika wrap), adhesives and two ways of strengthening beams exposed to bending moment are presented. Passive or slack reinforcement is one way of strengthening. The most effective way of such a strengthening was to place reinforcement laminates in the stretched part of the wooden beam (lower part in our case), in order to investigate the effectiveness of externally bonding FRP to their soffits. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, i.e., the wooden beam, the sika wrap composite plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the composite-wooden hybrid structures. The results showed that the use of the new strengthening system enhances the performance of the wooden beam when compared with the traditional strengthening system.

• Journal of Industrial Technology
• /
• v.24 no.A
• /
• pp.179-184
• /
• 2004

Each year, new technological advancements for repair-purpose are being introduced to overlay the old deterioration of RC bridge deck at highway by latex-modified concrete. The days may come when this old problem will be successfully resolved. While the experimental works and researches are very active at both laboratory and field, only a few theoretical studies were performed on interfacial problems, especially on stress distribution and concentration of RC beam overlayed by latex-modified concrete. The repaired and strengthened structures would induce a premature failure due to the stress concentration at the adhesive layer of different material before the design expected failure. This paper investigated and proposed an analytical model for predicting interfacial shear and normal stresses of RC beam repair-purpose overlayed by latex-modified concrete. This would be used for predicting interfacial stresses and preventing premature failure at interfaces. This study modified Smith-Teng method for applying to cementitious repairing material, which was based on a direct governing equation and linear-elastic approach for interfacial normal and shear stresses. The proposed theoretical model was verified using commercial FEA program, LUSAS, in terms of interfacial stresses predicted by the proposed model and calculated by LUSAS.

• Journal of the Microelectronics and Packaging Society
• /
• v.20 no.2
• /
• pp.11-15
• /
• 2013

The wafer bonding process becomes a flexible approach to material and device integration. The bonding strength in 3-dimensional process is crucial factor in various interface bonding process such as silicon to silicon, silicon to metals such as oxides to adhesive intermediates. A measurement method of bonding strength was proposed by utilizing AFM applied CNT probe tip which indicated the relative simplicity in preparation of sample and to have merit capable to measure regardless type of films. Also, New Tool was utilized to measure of tip radius. The cleaned $SiO_2$-Si bonding strength of SPFM indicated 0.089 $J/m^2$, and the cleaning result by RCA 1($NH_4OH:H_2O:H_2O_2$) measured 0.044 $J/m^2$, indicated negligible tolerance which verified the possibility capable to measure accurate bonding strength. And it could be confirmed the effective bonding is possible through SPFM cleaning.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.267-278
• /
• 2010

To improve the grout penetration characteristics, vibration method was adopted in this study. The grout material perturbed by cyclic vibration is injected into the ground. By applying the vibrating flow system, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibration grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at low grouting pressure of less than 400kPa.

• Journal of Ocean Engineering and Technology
• /
• v.24 no.1
• /
• pp.172-177
• /
• 2010

This study presents an explicit dynamic analysis of an adhesively bonded single-lap joint under an impact load. The finite element software, ANSYS LS-DYNA, was used for the analysis and Von Mises stresses were obtained from the analysis. To model the adherents, solid elements were used and a rigid body was assumed for impactor modeling. Three impact heights (1 m, 5 m, and 10 m) were applied to consider different impact conditions and infinite boundary conditions were applied to the end-area of each adherent to save computational time in the analysis. In addition to investigating the stresses in the normal state, we also investigated the stresses in a damaged state (elasticity deterioration), simulated by a change in Young's modulus for 36 of the 3600 elements in the upper layer of the adhesive. The results showed that the location of damage is critical to the stress state of each layer (upper, middle, and lower).

• Journal of Gastric Cancer
• /
• v.2 no.1
• /
• pp.29-32
• /
• 2002

A gastroduodenostomy is the most physiological reconstruction after a distal gastrectomy. However, a gastroduodenostomy with either sutures or staples has many complications. These include bleeding, leakage and stenosis. A sutureless gastroduodenostomy with a biofragmentable anastomosis ring (BAR) in was used adenocarcinoma patients to prevent these complications from 1999. A BAR is composed of polyglycolic acid and Barium sulfate to allow for X-ray visualization. Hardy in first introduced the BAR in 1985. Since then, it has been used in an anastomosis of the colon or small bowel surgery but its use in a gastroduodenostomy is the first trial in the world. A 70 year male patient, old who received a subtotal gastrectomy (Billroth I), underwent a A sutureless gastroduodenostomy with a BAR. The gastroduodenostomy with the BAR was watertight and maintained the initial burst strength in the gastrografin X-ray study performed at the postoperative 1 week. The BAR began to fragment 3 weeks after the operation and disappeared from the digestive tract completely. The diameter of the anastomosis site was sufficient for passed foods. No other secondary changes from remained foreign bodies were found in the endoscopic examination. In a second operation to treat a primary hepatoma, there was no adhesive changes around the gastroduodenostomy site. In conclusion, a sutureless gastroduodenostomy with BAR is a safe, easy and efficient reconstructive method after a distal gastrectomy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.279-280
• /
• 2008

For the manufacture of the $CuGaS_2$, Cu, Ga and S were vapor-deposited in the named order. Among them, Cu and Ga were vapor-deposited by using the Evaporation method in consideration of their adhesive force to the substrate so that the composition of Cu and Ga might be 1 : 1, while the surface temperature having an effect on the quality of the thin film was changed from R.T.[$^{\circ}C$] to 150$[^{\circ}C]$ at intervals of 50$[^{\circ}C]$. As a result, at 400$[^{\circ}C]$ of the Annealing temperature, their chemical composition was measured in the proportion of 1 : 1 : 2. It could be known from this experimental result that it is the optimum condition to conduct Annealing on the $CuGaS_2$ thin film under a vacuum when the $CuGaS_2$ thin film as an optical absorption layer material for a solar cell is manufactured.

• Journal of the Microelectronics and Packaging Society
• /
• v.6 no.3
• /
• pp.51-63
• /
• 1999

The effects of high filler loading technique on the reliability of epoxy molding compound (EMC) as a microelectronic encapsulant was investigated. The method of high filler loading was established by the improvement of maximum packing fraction using the simplified packing model proposed by Ouchiyama, et al. With the maximum packing fraction of filler, the viscosity of EMC wart lowered and the flowability was improved. As the amount of filler in EMC increased, several properties such as internal stress and moisture absorption were improved. However, the adhesive strength with the alloy 42 leadframe decreased when the filler content was beyond the critical value. It was found that the appropriate content of filler was important to improve the reilability of EMC, and the optimum filler combination should be selected to obtain high reliable EMC filled with high volume fraction of filler.

• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.292-298
• /
• 2001

An experimental investigation of the effect of composite patching repair was conducted to characterize the fatigue crack growth behavior in thick A16061-T6 (6mm) panels with single bonded patch by fiber reinforced composite patch. Four patch lengths and no patch plate were examined. An analytical procedure, involving three-dimensional finite element method having three layers to model cracked aluminum plate, epoxy by adhesive and composite patch, is calculated the stress intensity factors. From the calculated stress intensity factors, the fatigue crack growth rates are obtained. At the single patching type, different fatigue crack growth ratios through the plate thickness were investigated by using the experimental and analytical results. The results demonstrated that there was a definite variation in fatigue life depending on the size of composite patch. While crack reached the patch end, retardation of crack growth was also revealed in the bonded repair.