• Proceedings of the KWS Conference
• /
• 2000.04a
• /
• pp.139-143
• /
• 2000

Laser beam weldability of Zircaloy-4 was investigated using a pulsed Nd:YAG laser of 550W average power. Mechanical properties and microstructure of laser butt welded Zircaloy-4 test specimens were examined. The influence of laser generated during laser welding was analyzed and optimum laser welding parameters were investigated.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.1
• /
• pp.41-47
• /
• 2012

The LDS(Laser Direct Structuring) is one of the new direct writing methods to fabricate conductive patterns by energy beam. It uses thermoplastic polymers with an additive compound that serves as plating seed after the activation by laser. The advantages of LDS include the miniaturization of electrical components, design flexibility, and a reduced number of production steps. The purpose of this study is to investigate the fundamental mechanism for LDS and the characteristics of conductive patterns by laser parameters. These results were studied by SEM, EDX, and XPS analysis. We have used a 20W pulse-modulated fiber laser and copper electroless plating to fabricate conductive patterns on polymer. The result showed that electroless copper plating seed caused the laser cracking of additive compound. In particular, the additive compound contained in copper metal oxides atoms will be changed to copper metal elements. Also, the characteristics of conductive patterns were dependent on laser parameter, especially laser fluence.

• Journal of Acupuncture Research
• /
• v.22 no.5
• /
• pp.121-132
• /
• 2005

Objectives : The purpose of study was to compare and analyze the effect of the Intravascular Laser Irradiation Therapy and the Exterior vascular Laser Irradiation Therapy on Hypercholesterolemia. Methods : The 73 Sam-se-han-bang hospital patients who were irradiated to the Intravascular Laser and the 57 Sam-se-han-bang hospital patients who were irradiated to the Exterior vascular Laser were the study group. They had the treatment two or three times a week, and had checked total cholesterol before and after the ten times irradiation therapy. Results : Both the Intravascular Laser Irradiation Therapy and the Exterior vascular Laser Irradiation Therapy were effective on decreasing total cholesterol. The effect on decreasing total cholesterol was more definite at the abnormal group than the border line group, and the border line group than the normal group. The effect on decreasing total cholesterol was more definite at the Exterior vascular Laser Irradiation Therapy than the Intravascular Laser Irradiation Therapy, but this result was unavailable in the statistics. Conclusion : Both the Intravascular Laser Irradiation Therapy and the Exterior vascular Laser Irradiation Therapy had available effect on decreasing total cholesterol.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.11
• /
• pp.707-711
• /
• 2016

ITO/Ag/ITO conductive films on PET (polyethylene terephthalate) was etched by a Q-switched diode-pumped neodymiun-doped yttrium vanadate (Nd:YVO4, ${\lambda}=1064nm$) laser. During the laser direct etching, the laser beam was incident on the two different directions of PET and the etching patterns were investigated and analyzed. At a lower repetition rate of laser pulse, the larger laser etched patterns were obtained by laser beam incident on reverse side of PET substrate. On the contrary, at a higher repetition rate, it was possible to find the larger etched patterns in case of the laser beam incidence on forward side of PET substrate. For the laser beam incidence on reverse side, the laser beam is expected to be transferred and scattered through the PET substrate and the laser beam energy is thought to be dependent on the etch laser pulse beam energy.

• Laser Solutions
• /
• v.9 no.3
• /
• pp.7-13
• /
• 2006

Auto focusing system to find optimized focal position of laser beam used for material process has been investigated by using fiber confocal method. Wavelength of laser diode (LD) and diameter of single-mode fiber are 780nm and $5.3{\mu}m$, respectively. Intensity distributions of beam reflected from the surface of mirror and silicon bare wafer have been observed in a gaussian form. Experimental results show that focal position obtained by LD is shifted from one observed from surface scribed by laser about $80{\mu}m$. It is due to the difference of wavelength and each divergence of between LD and laser used for material process. It is confirmed that auto focusing control system through position calibration has operated steadily.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.11
• /
• pp.1-8
• /
• 1990

We made a 12-Laser Diode Array consisting of 12 Graded Index Separate Confinement (GRINSCH) InGaAs/Inp Buried Heterostructure 4 Quantum Well Laser Diodes and examined the potential of controlling lasing operation of each laser diode by the voltage to its electroabsorption region. Using Si V-Groove with 12 V-grooves, a 12-Laser Diode Array, and 12 optical fibers, we investigated the various characteristics of each laser diode by changing the voltage to its electro-absorption region. Finally, we thought over the promising way of implementing optical local area communication between electric circuit boards or between subscribers and a central office using a 12-Laser Diode Array, Si V-groove, and optical fibers.

• Korean Journal of Metals and Materials
• /
• v.50 no.3
• /
• pp.191-200
• /
• 2012

The purpose of this paper is to review the state of laser processing technology using metal powders. In recent years, a series of research and development efforts have been undertaken worldwide to develop laser processing technologies to fabricate metal-based parts. Layered manufacturing by the laser melting process is gaining ground for use in manufacturing rapid prototypes (RP), tools (RT) and functional end products. Selective laser sintering / melting (SLS/SLM) is one of the most rapidly growing rapid prototyping techniques. This is mainly due to the processes's suitability for almost any materials, including polymers, metals, ceramics and many types of composites. The interaction between the laser beam and the powder material used in the laser melting process is one of the dominant phenomena defining feasibility and quality. In the case of SLS, the powder is not fully melted during laser scanning, therefore the SLS-processed parts are not fully dense and have relatively low strength. To overcome this disadvantage, SLM and laser cladding (LC) processes have been used to enable full melting of the powder. Further studies on the laser processing technology will be continued due to the many potential applications that the technology offers.

• 전기의세계
• /
• v.13 no.4
• /
• pp.36-46
• /
• 1964

본고의 내용은 다음과 같다. 1. Laser의 원리 2. Laser의 실례 3. Laser광의 성질 4. Laser의 응용

• Journal of Sensor Science and Technology
• /
• v.22 no.1
• /
• pp.49-53
• /
• 2013

In this paper, we proposed a laser-based non-contact temperature measuring method for high speed rotating polycarbonate (PC) disk using transparency change of thermocolor. The thermocolor has abilities to change color and transparency due to a change in temperature. The thermocolor is applied on one side of polyvinylidene fluoride (PVDF) membrane. The thermocolor applied membrane is attached to inside of reaction chamber in disk. An optical system consisted of a laser beam radiator and a laser photometer is installed. Laser is irradiated at the bottom side of disk and the transmitted laser beam is detected by the laser photometer at the opposite side of disk. During the disk is rotating, laser is irradiated and detected simultaneously. The laser photometer senses the transmitted laser power and generates voltage as output. The temperature of disk can be detected during the disk is rotating up to 3000 RPM.

• Laser Solutions
• /
• v.8 no.3
• /
• pp.27-30
• /
• 2005

Nowadays, most automotives companies are making use of laser welding in car body assembly shop. But even though laser welding is better than resistance spot welding in many points, its application has been limited to special technology for manufacturing. The paper introduces in the field of remote welding system (RWS) to improve the process efficiency of laser welding. Positioning time of RWS between welding stitches is dramatically reduced to zero. It is a kind of solutions to generalize laser welding in mass production. This RWS consists of fiber laser, industrial robot and 3-axis scanner.