• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.9
• /
• pp.127-134
• /
• 2009

Laser-assisted machining uses primarily laser power to heat the local area before the material is removed. It not only efficiently reduces the cutting force during the manufacturing process but also improves the machining characteristics and accuracy with regard to difficult-to-machine materials. The prediction of relative deformations between the cutting tool and workpiece is important to improve the accuracy of machined components. This paper presents the deformation errors caused for a cylindrical workpiece by thermal effects in the laser-assisted machine tool using finite element method. The results can be used to increase the cutting accuracy by compensating thermal distortion prior to laser-assisted machining.

• Transactions of Materials Processing
• /
• v.12 no.5
• /
• pp.487-492
• /
• 2003

Tension variations with heat treatment in shadow mask for flat braun tubes are investigated in this study. In CRT, landing shift of the electron beam due to thermal deformation of the tension mask made the color purity of screen worse. In order to get the final results of thermal deformation, the tensile force within the mask and the welding processes between the rail and the extended mask have to be analysed sequentially. In this study, the effect of heat treatment is studied in terms of tension variations of shadow mask during its manufacturing process.

• Journal of Welding and Joining
• /
• v.7 no.4
• /
• pp.46-55
• /
• 1989

Zirconia coatings are performed by the plasma spraying on the substrate of Al-Si alloy. In case of plasma sprayed ceramic coatings, it is important to control properly residual stress occurred during cooling process. Residual stress in coating layer varies with sprayed conditions and is influenced greatly by the coating layer thickness. Surface residual stress due to coating layer thickness is measured by X-ray diffraction method and the residual stress in coating layer is estimated by the deflection of coating layer when the restraint force in substrate was removed. When zirconia was coated on the substrate, tensile residual stress remains on zirconia coated surface layer. The tensile stress is increased to 0.35mm thickness and after 0.45mm thickness it is decreased abrouptly. A thick bond and composite coating reduce the zirconia surface stress and composite coating controls effectively the thick zirconia surface stress.

• Steel and Composite Structures
• /
• v.34 no.2
• /
• pp.309-319
• /
• 2020

The objective is to study the deformation in a homogeneous isotropic modified couple stress thermoelastic medium with mass diffusion and with two temperatures due to a thermal source and mechanical force. Laplace and Fourier transform techniques are applied to obtain the solutions of the governing equations. The displacements, stress components, conductive temperature, mass concentration and couple stress are obtained in the transformed domain. Numerical inversion technique has been used to obtain the solutions in the physical domain. Isothermal boundary and insulated boundaryconditions are used to investigate the problem. Some special cases of interest are also deduced.

• Journal of Auto-vehicle Safety Association
• /
• v.6 no.1
• /
• pp.33-40
• /
• 2014

In this study the cylinder liner deformation which is one of the most influencing factors in a diesel engine oil consumption was performed by the finite element analysis on the basic designed structure consisting of the cylinder block, head and liners under the conditions of assembly, thermal and gas loads. Compared with a large number of other cylinder blocks showing remarkable harmonic orders of the liner distortion, results are excellent. Namely. the higher harmonic order amplitudes of the radial liner deformation amount to 1 ~ 2㎛ maximally. The main reason lies in the relatively large wall thickness of the liner which amounts to 8.2% of the bore diameter. Besides, a very stiff and symmetrical cylinder block design in combination with a bolt force introduction approximately 1.5mm below the block top deck have a further share on these results. Therefore excellent low oil consumption can be expected.

• The International Journal of Costume Culture
• /
• v.7 no.2
• /
• pp.103-111
• /
• 2004

The shrinkproof-finished wool fibers treated with resin coating and chlorination methods were used to find out an optimal shrinkproof finishing method keeping the quality properties of wool fabric to manufacturers. Shrinkage during repeated washing, electrostatic propensity, thermal resistance and pilling propensity of shrinkproof-finished wool knits, and analysis of finishing methods were measured. Upon the results from the surface examination of shrinkproof-finished wool fibers, the patterns of scale layer and degree of scale removal were subject to change according to the finishing processes. The shrink resistance was significantly enhanced on repeated washing of shrinkproof-finished knits, especially, chlorinated wool. Addition of strong physical force and alkali detergent applied in this washing experiment brought about superior effects with the low shrinkage rate although it was very severe washing conditions for wool fabrics. The results from the washing experiment implies that shrinkproof-finished knitted fabrics can be machine washed at individual households with other ordinary laundry. There was some changes and variation found in thermal resistance, electrostatic propensity, and pilling, however, it seems to be minor within standard limits. Therefore, shrinkproof-finished knitted fabrics did not bring serious changes to other physical properties comparing with original wool, which helps consumers handle wool knitted clothes more conveniently.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.18 no.6
• /
• pp.225-231
• /
• 2008

For an aspect ratio (transport length-to-width) of 5, Pr=1.13, Le=1.91, Pe=4.3, Cv=1.01, $P_B=20\;Torr$, the effects of addition of inert gas Ne on thermally buoyancy-driven convection ($Gr=2.44{\times}10^3$) are numerically investigated for further understanding and insight into essence of transport phenomena in two dimensional horizontal enclosures. For $10K{\leq}{\Delta}T{\leq}50\;K$, the crystal growth rate increases from 10 K up to 20 K, and then is slowly decreased until ${\Delat}T=50\;K$, which is likely to be due to the effects of thermo-physical properties stronger than the temperature gradient corresponding to driving force for thermal convection. The dimensional maximum velocity gratitude reflecting the intensity of thermal convection is directly and linearly proportional to the temperature difference between the source and crystal regions. The rate is first order-exponentially decreased for $2{\leq}Ar{\leq}5$. This is related to the finding that the effects of side walls tend to stabilize convection in the growth reactor. In addition, the rate is first order exponentially decayed for $10{\leq}P_B{\leq}200\;Torr$.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.290.2-290.2
• /
• 2016

Recently, organic thin-film transistors have been widely researched for organic light-emitting diode panels, memory devices, logic circuits for flexible display because of its virtue of mechanical flexibility, low fabrication cost, low process temperature, and large area production. In order to achieve high performance OTFTs, increase in accumulation carrier mobility is a critical factor. Post-fabrication thermal annealing process has been known as one of the methods to achieve this by improving the crystal quality of organic semiconductor materials In this paper, we researched the properties of pentacene films with X-Ray Diffraction (XRD) and Atomic Force Microscope (AFM) analyses as different annealing temperature in N2 ambient. Electrical characterization of the pentacene based thin film transistor was also conducted by transfer length method (TLM) with different annealing temperature in Al- and Ti-pentacene junctions to confirm the Fermi level pinning phenomenon. For Al- and Ti-pentacene junctions, is was found that as the surface quality of the pentacene films changed as annealing temperature increased, the hole-barrier height (h-BH) that were controlled by Fermi level pinning were effectively reduced.

• Journal of the Korean Vacuum Society
• /
• v.8 no.2
• /
• pp.93-101
• /
• 1999

The purposed of this paper is to investigate the electrical and thermal stability of Polyvinylidene fluoride(PVDF) organic thin films prepared by the vapor deposition method. The differential scanning calorimetry curve of the PVDF organic thin films prepared by increasing substrate temperature showed that the melting curve increased from $128^{\circ}C$ to $142^{\circ}C$. This result implied that the PVDF organic thin film prepared by increasing substrate temperature increased intermolecular force in the crystalline region. The anomalous properties in dielectric constant and dielectric loss at low frequency and high temperature were described for PVDF organic thin film containing impurity carriers. It was confirmed that in view of electric conductive characteristics the ohm's law is satisfied in the range of lower electric field and ln J was proportional to the electric field ln E as like the conventional property of ionic conduction in the range of higher electric field. It was confirmed that major carrier of conductivity was ions. The electrical stability was improved according to an increase of the substrate temperature. On the basis of this experimental result, it could be observed that the optimum temperature of substrate for the electrical and thermal stability was at $105^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.317-319
• /
• 2007

Recently, there were many researches for efficiency improvement of DSC. Among of these works, research of surface treatment is still a prerequisite for electron diffusion, light-harvesting and surface state of $DSC^{4)}$. Using of the surface treatment, it can be raise up porosity of $TiO_{2}$ nano-crystalline structure on $photo-electrode^{5)}$. There are chemical, physical, electrical and optical methods which raise up its porosity. In this paper, we have designed and manufactured MOPA-type ultrasonic circuit (100W, frequency and duty variable). Manufactured ultrasonic circuit to use to force cavity density and power into $TiO_{2}$ paste. Then, we have optimized forcing time, frequency and duty of ultrasonic irradiation for surface treatment of photo-electrode of DSC. In I-V characteristic test of DSC, ultrasonic and thermal treated DSC shows 19% improved its efficiency against established DSC.