• 한국전자현미경학회:학술대회논문집
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• 2000.05a
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• pp.27-30
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• 2000

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.43-43
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• 2008

• Polymer Science and Technology
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• v.11 no.6
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• pp.779-784
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• 2000

No Abstract, See Full Text

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.63-68
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• 2014

For a nanoscale Cu/low-k wafer, inter-layer dielectric (ILD) and metal layers peelings, cracks, chipping, and delamination are the most common dicing defects by traditional diamond blade saw process. Sidewall void in sawing street is one of the key factors to bring about cracks and chipping. The aim of this research is to evaluate laser grooving & mechanical sawing parameters to eliminate sidewall void and avoid top-side chipping as well as peeling. An ultra-fast pico-second (ps) laser is applied to groove/singulate the 28-nanometer node wafer with Cu/low-k dielectric. A series of comprehensive parametric study on the recipes of input laser power, repetition rate, grooving speed, defocus amount and street index has been conducted to improve the quality of dicing process. The effects of the laser kerf geometry, grooving edge quality and defects are evaluated by using scanning electron microscopy (SEM) and focused ion beam (FIB). Experimental results have shown that the laser grooving technique is capable to improve the quality and yield issues on Cu/low-k wafer dicing process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.20-20
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• 2010

The effect of excimer laser annealing on the structural and dielectric behaviors of $PbZr_{0.52}Ti_{0.48}O_3$ (PZT) thin films has been investigated. The amorphous PZT thin films were prepared on Pt/Ti/$SiO_2$/Si substrates by a sol-gel method. The PZT precursor was prepared from lead acetate, zirconium acetylacetonate, and titanium isopropoxide. The starting materials were dissolved in n-propanol and 1,3-propanediol. After, the amorphous PZT thin films were laser-annealed (using KrF excimer laser) as a function of the laser energy density and the number of laser pulse. Structural properties of PZT thin films are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric characterization was done on a RT66A test system and a Agilent 4294A impedance analyzer. The PZT thin films show that excimer laser irradiation drastically improved the crystallization and dielectric properties of the PZT thin films, depending on the energy density and the pulse number.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.7
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• pp.963-970
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• 2010

This study makes an estimate of the laser-assisted machining (LAM) of an economically viable process for manufacturing precision silicon nitride ceramic parts using a high-power diode laser (HPDL). The surface is locally heated by an intense laser source prior to material removal, and the resulting softening and damage of the workpiece surface simplify the machining of the ceramics. The most important advantage of LAM is its ability to produce much better workpiece surface quality compared to conventional machining. Also important are its larger material removal rates and longer tool life. The cutting force and surface temperature were measured on-line using a pyrometer and a dynamometer, respectively. Tool wear, chips and the surface of the workpiece were measured using optical microscopy, and the surface and fractured cross-section of $Si_3N_4$ were measured by SEM. During the LAM process, the cutting force and tool wear were reduced and oxidation of the machined surface was increased according to the increase in the laser power. Moreover, the more the feed rate increased, the more the cutting force and tool wear increased.

• Clinics in Shoulder and Elbow
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• v.4 no.1
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• pp.1-12
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• 2001

Purpose: To evaluate the histologic effect(LM and EM findings)of nonablative LASER and thermal energy on knee joint capsule of rabbit. Material and Methods: The nonablative LASER and thermal energy was applied to the rabits(average age 36 weeks, weight 5 ㎏). There were divided into 4 groups with 6 rabbits in each. The group I received 6 watts of LASER, group Ⅱ 12 watts of LASER, group Ⅲ 60° of thermal energy, and group Ⅳ 70° of thermal energy. The histologic study included H-E, Massons trichrome stain and electron microscopy at immediate, 3 weeks and 6 weeks after operation. Results: The histologic finding in immediate after operation was shown a fibrous degeneration of collagen on all groups and related to the energy level. The histologic finding after 3 weeks showed fibrosis and this fibrosis related the level of energy. Especially the group IV was shown flattening of capsule and deep fibrosis. The histologic finding after 6 weeks was shown marked recovery of collagen arrangement and capillary proliferation in group Ⅰ,Ⅱ and Ⅲ. But in the group Ⅳ not recovered. Conclusion: The nonablative LASER or thermal energy can cause degeneration, fibrosis and contracture of joint capsular collagen.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.35-44
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• 2009

The purpose of this paper is to describe experimental results about the T-joint welding of the high power continuous wave (CW) fiber laser for SAPH steel plate for seat frame of car. The seat rail is a part of seat frame of cars. The assembling method is mostly fix up using a bolt and nut. But this assembling method has many demerits in productivity such as increasing work process and material cost. This paper presents an experimental study about Laser T-Joint weldability of seat rail. Laser welding has many advantages in lightness and saving material costs of seat frame. The laser beam was moved along the work pieces by six axis robot with process optical fiber. The laser beam is focused with a welding head within incident angle $15{\sim}45^{\circ}$ for the purpose of the T-joint welding through two side full penetration. The range of the root gap size is less than ${\leq}0.4mm$. Optical microscopy SEM were performed to observe the micro structures and determine the structures of welded zone.

• Laser Solutions
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• v.4 no.3
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• pp.30-39
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• 2001

This work was tamed out to apply a laser welding technique in joining between a Zn coated low carbon steel plate(SECC) and a free cutting carbon steel shaft(SUM24L) with or without W coating. Experiments were carried out and analysed by applying the FD(factorial design)method to obtain the optimum Laser welding condition. Optical microscopy, SEM, TEM and XRD analyses were performed in order to observe the microstructures in the fusion zone and the HAZ. Mechanical properties of the welded specimens were examined by microhardness test, tensile test and twist test. There was no flawed Zn in the fusion zone by EDS analysis. This means that during the welding process, Zn gas could be eliminated by appropriate shielding gas flow rate and butt welding gap. Ni coating itself did not influence on the tensile strength and hardness. However, twist bending strength and the weld depth of the Ni-coated free cutting carbon steel were lower as compared with those of the uncoated free cutting carbon steel. It was attributed to a lower absorbance of laser beam to the shin Ni surface. According to the results of the factorial design tests, the twist bending strength of welded specimens was primarily affected by pulse width, laser power, frequency and speed.

• Korean Journal of Materials Research
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• v.11 no.9
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• pp.792-796
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• 2001

For electron beam lithography and SEM(scanning electron microscopy) applications, miniaturized electrostatic lenses called a microcolumn have been fabricated. In this paper, we report the fabrication technique for 20~30$\mu\textrm{m}$ apertures of electron lenses based on silicon and Mo membrane using an active Q-switched Nd:YAG laser. Experimental conditions of laser micromachining for silicon and Mo membrane are improved. The geometrical structures, such as the diameter and the preciseness of the micron-size aperture are dependent upon the total energy of the laser pulse train, laser pulse width, and the diameter of laser spot.