• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.54-59
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• 2012

This study dealt with effect of the grinding in SCM420H planetary gears. The hardness, tooth profile, lead and roughness of the gear surface can be improved by grinding process. Therein, the grinding techniques are widely used especially as one of the physical surface improvement methods. As the results, the gear grinding process reduced vibration and noise, and increased the life of the gear. And the gear grinding improved the surface of gear tooth in a short time and low cost, thus, it is a very important process in manufacturing industry. But nowadays, it is hard to find the detail information of gear grinding process. The test piece is a planetary gear which is used in the industrial machine. The manufacture process of the test piece contains hobbing, shaving, carburizing and grinding. This study investigated the effect of the grinding process to the physiognomy and the fatigue strength of test piece which was made by SCM420H.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.56-62
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• 2008

The biocompatibility and the fatigue strength of Co-Cr-Mo alloy are excellent, so it is used well for the material of artificial joints. The head of artificial joint needs mirror surface for reduction of abrasive resistance. Mirror finishing of Co-Cr-Mo alloy with geometrically defined single crystal diamond cutting tools is handicapped by micro chipping of tool edge. In general, it is said that the micro chipping of diamond tool is caused by work hardening of Co-Cr-Mo alloy for the cut. In the present research, mirror finishing of Co-Cr-Mo alloy by applying ultrasonic elliptical vibration cutting was carried out. The experimental results show that the micro chipping of diamond tool was suppressed and the tool wear was remarkably reduced as compared with the ordinary diamond cutting without elliptical vibration motion. It was confirmed that the good mirror surface of maximum surface roughness of 25 nmP-V was obtained for the cutting length of about 14 m. It is expected that mirror finishing of Co-Cr-Mo alloy can be achieved by applying ultrasonic elliptical vibration cutting practically.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.38-44
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• 2008

Titanium and its alloys, due to their superior properties of high specific strength and excellent corrosion resistance, are increasingly used in living applications in the 21century. The applications in aerospace and medical industries demand machining process more frequently to obtain a desired product. But unfortunately, this material is one of the most difficult-to-cut. In the turning process of titanium alloys, the key point for successful work is to select proper tool materials and cutting conditions. This study suggests a guidance for selecting the tool materials and the cutting speeds to improve tool life and surface integrity in Ti-6Al-4V titanium turning process. The experiments investigate the change of surface roughnesses, cutting forces and flank wear with various cutting parameters of tool materials, depth of cuts and feeds. As the results, K10 type of insert tip was assured as the best for turning of Ti-6Al-4V titanium alloy.

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.206-215
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• 2017

Objectives: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide ($Al_2O_3$) particles at different pressures. Materials and Methods: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and ${\chi}^2$ tests (${\alpha}=0.05$). Results: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.

• Magazine of the Korea Concrete Institute
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• v.7 no.1
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• pp.109-116
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• 1995

In tnis study, the impact factors of a simply supported highway bridge due to a vehicle moving across the span are presented. This variable has received cons~derable attention in recent years, both analytically and experimentally. The KBDC specification equation has a maximum 30 percent value which decreases with span length. The results of field tests showed that the dynamic load effects are mostly lower t.hari present KBDC value and that the impact factor does not vary significantly with spar1 as implied in KHUC. The rnain parameters affecting lmpact are the br dge approach. bumps, and other pavement roughness. In thls study, based on test results, three values of impact factors are provided by correlating the roughness of the surface to the deck condition survey values. The present study proposes reasonable impact factors for the strength evaluation of highway bridges. This study may be extended to the evaluation of existing brdges.

• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.134-140
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• 2000

Si wafer direct bonding(SDB) technology is very attractive for both Si-on-insulator(SOI) electronic devices and MEMS applications. This paper presents on pre-bonding according to HF pre-treatment conditions in Si wafer direct bonding. The characteristics of bonded sample were measured under different bonding conditions of HF concentration and applied pressure. The bonding strength was evaluated by tensile strength method. A bond characteristic on the interface was analyzed by using FT-IR, and surface roughness according to HF concentration was analyzed by AFM. Si-F bonds on Si surface after HF pre-treatment are replaced by Si-OH during a DI water rinse. Consequently, hydrophobic wafer was bonded by hydrogen bonding of Si-OH$\cdots$(HOH$\cdots$HOH$\cdots$HOH)$\cdots$OH-Si. The pre-bonding strength depends on the HF pre-treatment condition before pre-bonding. (Min : $2.4kgf/cm^2{\sim}$Max : $14.9kgf/cm^2$)

• Composites Research
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• v.17 no.6
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• pp.14-21
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• 2004

Failure process, mode and strength of unidirectional composite single lap bonded joints were investigated experimentally with respect to bonding methods, those are, co-curing with and without adhesive and secondary bonding. The co-cured joint specimens without adhesive had the largest failure strength. Progressive failures along the adhesive layer occurred in the secondary bonded specimens. In the co-cured specimens with adhesive film which had better material strength and adhesion performance, delamination failure occurred and the joint strengths were less than those of secondary bonded specimens. Delamination failure did not occur in the secondary bonded specimens because of earlier crack growth and progressive failure in the adhesive layer. Therefore, failure strength of composite bonded Joints were not always proportionate to material strength and adhesion performance of the adhesive due to the weakness of delamination in composite materials. The effects of surface roughness, bondline thickness and fillets were also studied on secondary bonded specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.156-165
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• 2011

This study investigates the horizontal shear behavior of an interface between precast concrete (PC) and topping concrete(RC), and evaluates the horizontal based on the investigations by the experimental. Horizontal shear strength in connected surface is determined by the roughness an interface and the shear reinforcement or not. In this study, the main experimental parameters are the shear reinforcement types in the shape of loop-type and lattice-type, rebar spacing. A total of four specimens were shear strength tested and manufactured. As a result, the horizontal shear strength of reinforced connected surface was found to be controlled by deformation in vertical direction. Comparison of reinforcement shape, the mean initial crack load loop type specimens, the average maximum load and the junction of the average in terms of initial stiffness, respectively 33.7%, 45.9% and 55.2% were large enough. Evaluation results for shear strength equation of existing standard domestic, the loop-type reinforced 2.32 to 4.23 times, lattice-type reinforced 1.65 to 3.06 times appears to be higher. Behavior of interface or strength of structural design criteria was fairly safe side. It does not have any problems in the applied field is considered.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.2
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• pp.1-8
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• 2019

The demand and importance of adhesives and paint coatings applied to solid surfaces such as metals, ceramics, and plastics are increasing. In this study, the influencing factors on the adhesive strength between the polymer coating and the metal adherend were investigated by Dolly test when the adhesive or the paint coating was applied on the metal adherend. Two-component epoxy adhesive was used as the adhesive, and EH2350, a two-component epoxy paint for anti-corrosion, was used as the paint. Especially, the effect of adherend metals(Al, Fe, STS, Cu, Zn), surface roughness and surface contamination(tap water, salt water) on adhesive strength was studied as influencing factors. The adhesive strength between adhesive and adherend was different when the type of metal adherend was different even when the same adhesive was used. It was found that spray water cleaning was necessary before the paint coating process on the surface of the oxide contaminated adherend with tap water or salt water. As a result of this study, it was confirmed that Dolly test can be widely used in the future to measure adhesive strength between paint coating and adherend.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.2 s.120
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• pp.25-30
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• 2007

Recently the use of web offset printing has been increasing, which can provide high print speed, mass production, and high print quality. However, high speed web offset printing has frequently undergone a blistering problem when the printed paper passes through hot air dryers. Blistering occurs in the middle of the base paper or in the coating layer. This paper focused on the blistering occurring in the base paper. In order to elucidate the effect of pigment ratio on blistering, 6 types of coating color were prepared with varying GCC/clay ratios and printability and blistering were investigated focusing on structure changes in the coating layer. When the clay content in the coating layer was increased, surface roughness and surface strength were decreased and paper gloss was increased. In addition, it was found that the coating layer structure with high clay content, which contains lots of discontinuous pores, hindered water vapors to penetrate out and, as a result, blistering occurred.