• Korean Journal of Materials Research
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• v.14 no.1
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• pp.1-8
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• 2004

Laser weldability of aluminized steels for deep drawing application has been investigated. Test coupons for Nd:YAG laser welding and $CO_2$ laser welding were prepared trom the commercial steels. According to the test results, total penetration and back bead width of aluminized steels were sensitive to the welding conditions. Bead width at the half thickness of the overlap joint, however, was rather constant. Laser weldability of aluminized steels was superior to that of zinc coated steel. Weld microstructure revealed that overlap zone adjacent to the fusion line was filled with coated materials, which was thought to be desirable to protect weld from crevice corrosion. The aluminum coated materials was also found in the weld metal. Practically no spattering was observed in the laser welding of aluminized steels even when the welding was performed without joint gap. In the welding of zinc coated steel, however, spattering was so severe that it was difficult to get the acceptable weld. Bead quality of aluminized steel laser weld was smooth and stable.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1627-1630
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• 2004

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266nm. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $300{\sim}450^{\circ}C$ and flow rate of 100${\sim}$700 seem. In order to investigate the effect of post-annealing treatment of ZnO thin films, films have been annealed at various temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction(XRD) and the optical properties of the ZnO were characterized by photoluminescence(PL).

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2079-2082
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• 2004

This paper study on OLEDs(Organic Light Emitting Diodes) panel using PLD(Pulsed Laser Deposition) methode. Deposition of organic was used Q-stitched Nd/YAG laser in 355 nm and reduced organic pellet for PLD method. Organic morphology was measured AFM(Atomic Forced Microscope) and emitting efficiency was measured luminance meter.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.163-170
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• 1997

The MgO-doped LiNbO$_3$ single crystals were grown along c-axis by the Czochralski method with the pulling rate of 3mm/h and the rotation of 10rpm. The MgO contents were form 1 to 4 mole%. The SHG properties were investigated with the pulsed Nd:YAG laser, and thermo-optic coefficient, electro-optic coefficient of birefringence and curie temperature were measured. Phase matching temperature and Curie temperature increase similarly with MgO content until 4 mole%.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1347-1349
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• 1995

Insulators contaminated by salt particles may cause flashovers in humid climate or light rain. Therefore, the quantity of salt on insulators should be monitored not to exceed a critical value. We propose a new remote sensing technique to measure the quantity of salt on insulators of power systems. The amount of the salt is measured from the intensity of the spontaneous emission from the sodium atoms. In this paper, a compact remote on-line salt-meter composed of Q Switch pulsed Nd:YAG laser and emission signal detection system will be introduced. And as the first result of this study, the operating characteristics of our developing laser system is also introduced.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.1-11
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• 1997

The soot and OH radical distributions have been experimentally studied in ethylene and propane laminar diffusion flames. The integrated soot volume fraction was measured along the centerline of a flame using a laser light extinction method. Planar laser light scattering and PLIF techniques are employed for the soot and OH radical distribution measurements utilizing Nd:YAG laser and OPO, FDO system. The concentration of OH radical is rapidly decreased at the edge of sooting region, which implies the importance of OH radical species on the soot oxidation process. For ethylene flames, the addition of air in fuel moves the OH radical distribution towards the center line of a flame at the soot oxidation region, while the concentration of OH radical remains relatively high at the soot formation region. The interaction between soot particles and OH radicals becomes more active with fuel-air at the soot oxidation region. For propane flames, however, any indication of the increased interaction between soot particles and OH radicals with fuel-air was not noticed.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.20-21
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• 2001

실리콘 나노결정 박막은 Nd:YAG 레이저를 사용한 펄스레이저 증착법으로 p형 (100) 실리콘 기판위에 형성되였다. 증착 후, 다양한 분위기 가스와 $400^{\circ}C$에서 $800^{\circ}C$까지 범위의 여러 온도에서 후열 처리가 수행되었다. 후열 처리가 끝난 시료 중 일부는 혼합가스(95 % $N_2$ + 5 % $H_2$)에서 한시간 동안 수소 passivation을 수행하였다. 실온에서 강한 청자색 photoluminescence (PL)을 관찰할 수 있었다. 이 논문에서 우리는 다양한 후열처리 조건과 수소 passivation 효과에 따른 PL 특성 변화를 제시하고, 이 결과를 통해 실리콘 나노결정 박막의 발광 메카니즘을 간접적으로 유추하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.86.1-86.1
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• 2010

Cu2ZnSnSe4는 CIS 태양전지의 In 대체 물질계로 주목을 받고 있는 저가형 태양전지 재료로 장차 차세대 태양전지 재료로 응용이 기대되고 있다. 그러나 에너지 밴드갭이 0.9~1.1eV로 다소 낮아 태양전지 광흡수층 재료로 사용하기 위해서는 wide band gab화 처리가 필요하다. 본 연구에서는 CZTSe에 S를 첨가하여 에너지 밴드갭을 확장하고자 하며, S의 첨가가 CZTSe 박막의 특성에 미치는 영향에 대하여 조사하였다. 실험의 편의성을 도모하고자 펄스레이저 법을 사용하여 증착하였다. 박막 조성 제어에는 Cu, Zn, Sn, Se, S 분말을 볼밀로 분쇄, 혼합하여 균질 혼합상 프리커서를 제조하고 이를 Cold Isostatic Press(CIP) 성형하여 Source target을 사용하였다. Pulsed YAG-Laser를 사용하여 soda lime glass상에 증착하고 조성, 구조, 조직을 관찰하고 에너지 밴드갭, 광흡수계수, 면저항, 전하밀도 등 특성을 조사하였다.

• Laser Solutions
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• v.15 no.1
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• pp.1-5
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• 2012

Recently ultra high strength steels(UHSS) has been widely applied to the structural or safety components in the automotive industry. Specially, hot stamping boron steel 22MnB5 has shown the crash-resistant characteristics when applying to bumpers and pillars. Lap joint Laser welding of the hot stamped and die quenched sheets of Boron steel was carried out using 3kW Nd/YAG laser. The appropriate Lap joint laser welding conditions were founded separately for four lap joint combinations. The lower sheest is a hot stamped sheet in common and the upper sheet is selected among the hot stamped steel and high strength steels such as SPCC, 370MPa, and 590MPa grade high strength steels. Cross bead sections and local hardening and softening were observed as well as tensile-shear test results.

• Laser Solutions
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• v.15 no.1
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• pp.10-14
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• 2012

Pulse laser welding was performed on C22 metal bellows. The results can be summarized as follows: Laser welded metal bellows had less thermal distortion, narrow HAZ, high aspect ratio in comparison with other welding processes like TIG, Plasma welding. Laser welded bellows has higher tensile strengths than that C22 base metal. The value of hardness in laser weld metal was measured 100-120 Hv, it was decreased compared to the base metal. It is reasoned that due to the annealed by heat input during the laser welding.