• Journal of Welding and Joining
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• v.3 no.2
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• pp.27-34
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• 1985

The mechanical properties and bonding mechanism of aluminum, copper and mild steel have been determined in cold pressure welding. The brittle cover layer to be established by scratch-brushing plays an important role in bond strength and has an influence on the threshold of deformation. The cold pressure welding was achieved at 54% of height reduction in A1-A1, 75% in Cu-Cu, 56% in Al-Cu, and 74% in Cu-steel. The height reduction at which the bond strength of weld interface was the same as the tensile strength of base metal should be over 76% in Al-Al, 82% in Cu-Cu, and 78% in Al-Cu.

• Journal of Welding and Joining
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• v.12 no.2
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• pp.39-48
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• 1994

In comparison to the conventional brazing, laser welding of ceramics has advantages of direct bonding without filler material, which causes the thermal stress due to the differences of thermal expansion coefficients. In pulse-mode, laser welding of dispersion ceramic having high thermal resistance is possible at relatively low preheating temperature of $1300^{\circ}C$ In CW-mode, alumina can be welded at high preheating temperature $1500^{\circ}C$ under the condition of low feed rate of 500 mm/min, respectively. Further studies on developing mechanism of pores in the bead during laser welding of ceramics is required.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.179-180
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• 2015

pure Mg and some Mg alloys are relatively rapidly corroded after operation, resulting in the decrease of mechanical strength and change of local ion concentration. In this study, the corrosion mechanism of biodegradable implant materials was investigated by corrosion tests of the Mg alloy in Hank's solution. Particularly, the crystal structures and chemical bonding state of corrosion reactants was systematically examined.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.113-119
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• 2022

In order to improve the mechanical reliability of next-generation electronic devices including flexible, wearable devices, a high level of mechanical reliability is required at various flexible joints. Organic adhesive materials such as epoxy for bonding existing polymer substrates inevitably have an increase in the thickness of the joint and involve problems of thermodynamic damage due to repeated deformation and high temperature hardening. Therefore, it is required to develop a low-temperature bonding process to minimize the thickness of the joint and prevent thermal damage for flexible bonding. This study developed flexible laser transmission welding (f-LTW) that allows bonding of flexible substrates with flexibility, robustness, and low thermal damage. Carbon nanotube (CNT) is thin-film coated on a flexible substrate to reduce the thickness of the joint, and a local melt bonding process on the surface of a polymer substrate by heating a CNT dispersion beam laser has been developed. The laser process conditions were constructed to minimize the thermal damage of the substrate and the mechanism of forming a CNT junction with the polymer substrate. In addition, lap shear adhesion test, peel test, and repeated bending experiment were conducted to evaluate the strength and flexibility of the flexible bonding joint.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.113-119
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• 1999

In this study, the incineration of MEK and toluene was studied on a Pt supported alumina catalyst at temperature range from 200 to $350^{\circ}C$. An approach based on the Mars-van Krevelen rate model was used to explain the results. The object of this study was to study the kinetic behavior of the platinum catalyst for deep oxidation. The conversions of MEK and toluene were increased as the inlet concentration was decreased and the reaction temperature was increased. The maximum deep conversion of MEK and toluene were 91.81% and 55.69% at $350^{\circ}C$, respectively. The ${\kappa}_3$ constant increases with temperature faster than the ${\kappa}_1$ constant, that is, the surface concentration of ($VOCs{\cdots}O$) is higher than that of (O) at higher temperature according to the Mars-van Krevelen mechanism. Also the activation energy of toluene was larger than MEK for toluene is aromatic compound which have stronger bonding energy.Therefore, the catalytic incineration kinetics of MEK and toluene with Mars-van Krevelen mechanism could be used as the basic data for industrial processes.

• Journal of the Korean Ceramic Society
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• v.31 no.12
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• pp.1443-1448
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• 1994

Pb(Mg1/3Nb2/3)O3-PbTiO3-BaTiO3 solid solution was formed by mixed-oxide method. The phase during formation was analysed by XRD and formation mechanism was investigated. While heat-treating Pb(Mg1/3Nb2/3)O3 composition, the first, Pb2Nb2O7 and Pb3Nb2O8 pyrochlore phases are formed, and finally Pb(Mg1/3Nb2/3)O3 perovskite phase with containing Pb3Nb4O13 pyrochlore phase is obtained at 80$0^{\circ}C$. When Pb(Mg1/3Nb2/3)O3 composition is modified with PbTiO3 which have strong ionic bonding and high tolerance factor, the amount of pyrochlore phase is decreased by increasing of stability in perovskite structure.

• KCI Concrete Journal
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• v.12 no.2
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• pp.31-43
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• 2000

The extensive usage of pretensioned prestressed concrete component in modem construe- tion as structural members mandates precise understanding of its mechanism. Especially, an adequate transfer of prestressing force from steel tendons to concrete around the end regions of the member is a critical issue. Due to the importance of the topic, several investigators have formulated equations modeling the transfer bond length based on various bonding mechanism between steel and concrete. However, the existing models are still inadequate in predicting the bond development in pretensioned prestressed concrete members. Therefore, this study presents a model of transfer bond length based on rational theory that can simulate experimental results. The model is developed into solid mechanics based structural analysis computer program. The program is validated by comparing the analysis results with experimental results of bond stress distribution, concrete strain profiles, and transfer length in pretensioned prestressed concrete members. The proposed analytical procedure in this study can be utilized as a useful tool for realistic evaluation of transfer length in pretensioned prestressed concrete members.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.936-940
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• 2007

The aminolyses of diphenyl phosphinic chloride (1) with substituted anilines in acetonitrile at 55.0 oC are investigated kinetically. Large Hammett ρ X (ρnuc = ?4.78) and Bronsted β X (βnuc = 1.69) values suggest extensive bond formation in the transition state. The primary normal kinetic isotope effects (kH/kD = 1.42-1.82) involving deuterated aniline (XC6H4ND2) nucleophiles indicate that hydrogen bonding results in partial deprotonation of the aniline nucleophile in the rate-limiting step. The faster rate of diphenyl phosphinic chloride (1) than diphenyl chlorophosphate (2) is rationalized by the large proportion of a frontside attack in the reaction of 1. These results are consistent with a concerted mechanism involving a partial frontside nucleophilic attack through a hydrogen-bonded, four-center type transition state.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.642-645
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• 1998

The aminolysis reactions of phenylacetyl chlorides with anilines and N,N-dimethylanilines (DMAS) in acetonitrile at -15.0 ℃ are investigated. The magnitude of ρx (= -2.8 ∼ -2.9) and ρy (= 0.9 ∼ 1.3, after correcting for the fall-off), and the negative sign of ρxy (= -0.12) for the reactions with anilines suggest an associative SN2 mechanism. For the reactions with DMAs, the magnitude of these Hammett coefficients increases so that tighter bond making in the transition state (TS) is predicted. A nonlinear Hammett plots obtained for the DMAs with an electron acceptor substituent is interpreted to result from a more advanced degree of leaving group departure to assist closer approach of the bulky DMA in the TS. The normal secondary kinetic isotope effects $(k_H/k_D>1.0)$ involving deuterated anilines suggest partial deprotonation by hydrogen bonding to the departing chloride ion.

• Archives of Plastic Surgery
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• v.50 no.2
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• pp.142-147
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• 2023

Some of Asian eyelids have double fold and some do not. Many people tend to prefer double eyelid in aesthetic and functional reasons. Since the mechanism of double eyelid is bonding the eyelid skin to the eye-opening tissue, the principle of double eyelid surgery is also connecting the eyelid skin to levator component. Double eyelids are differentiated by their shape according to the height and curvature. The double eyelid surgery procedure is divided into incision method and nonincision method. And the incision method is subdivided into double fold line design, skin and oculi muscle incision or excision, pretarsal or preaponeurotic soft tissue excision, fixation of posterior lamella to anterior lamella, and skin suture. The nonincision method is to connect the posterior lamella and the anterior lamella as a thread only without an incision. A successful double eyelid surgery creates a fold well-balanced in height, curvature, and depth of the fold based on patient's preference. In this article, the author's own methods of performing surgery are described, with a step-by-step guide and surgical tips.