• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1085-1093
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• 1999

Thickness effects of coupling agent on residual bending stress were investigated in $Polyimide/SiO_2$ joints during thermal cycling. Thickness and peel strength of $\gamma$-APS coupling agent were measured and correlated with solution concentration and residual bending stress. The variation of residual bending stress with temperature was also measured for various thicknesses of the coupling agent. Finite element results were compared with experimental data for residual bending stress in $Polyimide/SiO_2$ joints.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.266-269
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• 2005

The effect of exit temperature on the thickness of recrystallization layer during Al extrusion process was investigated. The recrystallization layer of an extruded Al alloy is an important feature of the product in a wide range of applications, particularly those within the automotive industry. The thicker recrystallized layer in the Al alloys can give rise to a number of problems including reduced fatigue resistance and orange peel during cold forming. But the interaction of extrusion process variables with the thickness of recrystallization layer is poorly understood, and there is limited information available regarding the role of the main hot extrusion variables. Using the 3650 US ton extrusion press, this paper describes the effect of the main process variables such as billet temperature, ram speed, and exit temperature on the thickness of recrystallization layer for the A6XXX Al alloy.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.491-498
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• 2001

The failure phenomenon of overlaid concrete structures, such as surface crack and peel-off failure in the contact zone, was investigated due to temperature shock(rainfall). To investigate this failure phenomenon, the surface tensile stress, and the shear stress, the vertical tensile stress in the contact zone were analysed using the non-linear stress-strain relationship of material such as strain-hardening- and strain-softening diagrams. Rainfall intensity, overlay thickness and overlay material were the main variables in the analyses. It is assumed that the initial temperature of overlaid concrete structures was heated up to 55$\^{C}$ by the solar heat. With a rain temperature 10$\^{C}$ and the rainfall intensity of nR=1/a, tR=10min, 60min, the stress states of overlaid concrete structures were calculated. The result shows that only fictitious cracks occurred in the overlay surface and no shear bond failure occurred in the contact zone. The vortical tensile stress increasing with overlay thickness was proved to be the cause of peel-off failure in the contact zone. The formulae for relationship between the vertical tensile stress and overlay thickness, material properties were derived. Using this formulae, it is possible to select proper material and overlay thickness to prevent failure in the contact zone due to temperature shock caused by rainfall.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1178-1183
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• 1999

Essential oils were isolated from the peel of mandarin (Citrus unshiu Marc. Var. Okitsu) cultivated in Cheju Island. Among three different isolation methods investigated, simultaneous distillation gave higher yield 1.14%(w/w) than solvent extraction or cold pressing. The densities of essential oils were between 0.8409 and 0.8530, which showed no significant effect of the isolation methods. Some variations in the number of constituents detected and the content of d-limonene in the peel oils were observed depending upon the isolation methods. The citrus fruit was collected seasonally from the field and used as a sample for analysis. The peel thickness and the peel content of citrus fruit were around 2 mm and about 17% on wet weight basis, respectively, in harvest season. The maximum yield of essential oils was obtained in September from citrus peels just prior to ripeness and thereafter the yield had a tendency of decrease but remained over 1%(w/w). The relative content of d-limonene, the major constituent of citrus peel oils. increased gradually with ripening up to 68.69%(relative peak area, RPA). The other minor constituents were ${\gamma}-terpinene,\;{\beta}-elemene$, farnesene, hexadecanoic acid, ${\alpha}-pinene,\; {\beta}-myrcene$ and linalool in the decreasing order of their own contents of 7.75, 2.96, 2.29, 1.76, 1.63, 1.56 and 1.46%(RPA).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.752-760
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• 2000

Mechanical press joining has been used in sheet metal joining processes because of its simple process and possibility of joining dissimilar metals, such as steel and aluminum. The strength of mechanical press joining varies with joining conditions. The optimum joining conditions considering tensile-shear and peel-tension strength have to be established to assure the reliability in the joining strength. Therefore, optimization of joining conditions has been investigated for improving joining strength of sheet metal. It is possible to obtain optimum strength from improvement on the joining strength of peel-tension mechanical press joint under multiaxial stress states.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.465-470
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• 2001

The adhesively-bonded joints considered in this investigation include single-lap joint and double-lap joint. For an adhesively bonded double-lap joint, end mismatch between the two cuter adherends(upper, lower) can not removed completely although it can be controlled within a manufacturing tolerance. This paper shows that the end mismatch introduces local bending and end mismatch affects the shear and peel stresses in the adhesive. The double-lap joint with an end mismatch is affected of adhesive thickness, material properties of adhesive and adherend etc. Also, we concluded that there are critical value of an end mismatch to provoke the interface fracture.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.94-96
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• 2005

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tensile and peel tests were carried out on specimen manufactured hybrid stacked composites such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the failure strength of adhesive bonded joints using hybrid stacked composites with a polyester and bamboo natural fiber layer adjacent to the fiber orientation. From results, the load directional orientation, small amount and low thickness of bamboo natural fiber layer have a good effect on the tensile and peel strength of natural fiber reinforced composites. and these characters are have a great influence on fracture strength and failure shape of adhesive bonded joints using hybrid stacked composites in the difference of fiber orientation.

• Food Science and Preservation
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• v.24 no.6
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• pp.727-733
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• 2017

We investigated the effect of PE film thickness on the modified atmosphere packaging (MAP) deastringency of 'Sanggamdungsi' (Diospyros kaki cv.) astringent persimmon at room temperature ($25^{\circ}C$) and low temperature ($-1^{\circ}C$). The fruits were individually packaged with PE film of which the thickness is 60, 80, 100, 115 or $130{\mu}m$ and stored at room or low ($-1^{\circ}C$) temperature. At room temperature, firmness shows the highest value (23.3-26.5) at $100{\mu}m$ thickness. Top flesh browning and decay was monitored at 20 days after storage, and peel blackening and style-end softening was negligible at optimal thickness. Therefore, optimal film thickness of deastringency at room temperature is $80-100{\mu}m$. At this thickness, the astringency was removed after 5 days and the fruits can be distributed until 10 days after the MAP. At low ($-1^{\circ}C$) temperature, firmness was maintained regardless of film thickness. However, the firmness is higher as the film is thicker. Top flesh browning and decay was not occurred even after 90 days after storage. Peel blackening and style-end softening was monitored at 90 days after storage. Off-flavor was monitored at 115 and $130{\mu}m$ thickness. Therefore, optimal film thickness of deastringency at low ($-1^{\circ}C$) temperature is $80-100{\mu}m$. At this thickness, the astringency was removed after 50 days and the fruits can be distributed until 80 days after the MAP.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.363-363
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• 2006

Bonding of composite materials with an adhesive layer is one of the most promising alternatives to classical bonding techniques. The use of several surface treatments may greatly increase this adhesion behavior at the initial state. Then in order to see the influence of the thickness of polymer matrix on the adhesion of composite assembly, different surface treatment, which can reduce or increase this thickness, are used (peel ply, tear ply, excimer laser). The influence of this specific parameter is not only discussed at the initial state but also after thermal ageing of the whole bonded assembly. Results show that the best performances at the initial state are not obviously the best performances after ageing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.695-696
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• 2009