• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.81-87
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• 1994

We used IR laser inteferometric technique for measuring the temperature of wafer during cryogenic ECR etching. Using this technique, the effect of RF bias power and microwave power on the wafer temperature during etching period is investigated. As the RF bias power and microwave power was increased, the temperature of the wafer considerably increased and we concluded that to prevent the increase of substrate temperature during etching period, an adequate wafer cooling is needed.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.4
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• pp.761-771
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• 1998

In this study, attempt has been made to evaluate the effect of $CO_2$ laser irradiation on enamel surface structure and the bond strength of sealant material. Conventional acid etching was used as a control technic for comparison. The results obtained from this experiment were as follows; 1. The highest mean shear bond strength value was observed in samples of Group I (acid-etching) with the statistical significance(p<.05) between all the other groups. 2. The shear bond strength in Group IV was the lowest among laser etching groups. but there were no significant difference between them(p>.05). 3. Scanning electron microscopic observation showed that the rough and irregular surface was created by $CO_2$ laser treatment with the formation of numerous pores, micro-cracks, and small bubble-like inclusion. Increasing the energy density induced localized surface melt with a thin smooth glaze-like appearance. 4. In acid-etched control specimen cohesive failure predominated, whereas adhesive failure was the main mode in laser-treated group. Based upon the above-mentioned results, it can be assumed that the $CO_2$ laser is not an adequate substitute for the acid-etch technique in enamel preconditioning. More studies are required to explore the effective condition of laser irradiation which could attain the better bond strength of restorative materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.795-796
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• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.253-254
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• 2011

• Proceedings of the Korean Society of Laser Processing Conference
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• 2001.11a
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• pp.37-41
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• 2001

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1089-1095
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• 2012

Laser beam machining (LBM) using nanosecond pulsed laser is widely known to be rapid and non-wear process for micromachining. However, the quality itself cannot meet the precision standard due to the recast layer and heat affected zone. In this paper, a fabrication method for machining micro features in stainless steel using a hybrid process of LBM using nanosecond pulsed laser and electrochemical etching (ECE) is reported. ECE uses non-contacting method for precise surface machining and selectively removes the recast layer and heat affected zone produced by laser beam in an effective way. Compared to the single LBM process, the hybrid process of LBM and ECE enhanced the quality of the micro features.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.75-81
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• 2014

Laser beam machining has been known as efficient for glass micromachining. It is usually used the ultra-short pulsed laser which is time-consuming and uneconomic process. In order to use economic and powerful long pulsed laser, indirect processing called laser-induced backside wet etching (LIBWE) is good alternative method. In this paper, micromachining of glass using Nd:YAG laser with nanosecond pulsed beam has been attempted. In order to improve shape accuracy, combined processing with magnetic stirrer has been widely used. Magnetic stirrer acts to circulate the solution and remove the bubble but it is not suitable for deep hole machining. To get better effect, ultrasonic vibration was applied for improving shape accuracy.

• Laser Solutions
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• v.11 no.1
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• pp.7-11
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• 2008

Decapsulation technology is useful to inspect EMC of package device and the etching technology enable to check inside of device by removing plastic molding. Chemical etching method is used widely to fabricate a lot of semiconductor. But the method has some disadvantage due to wet process. Proposed method in this paper shows the application possibility such as fast processing time, processing accuracy and dry process. These result was obtained by directly removing of packed EMC using UV laser.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.38-46
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• 2005

In laser machining such as drilling with $CO_2$ or Nd:YAG laser, and etching or ablation with Excimer laser, one of the most important parameters affecting the machining is known to be beam characteristics. In this paper a numerical study is performed to investigate the effects of beam parameters, especially in the process of excimer laser ablation of polymers. Results of different beam conditions reveal that if the ablated depth is small compared to beam size the simple photochemical etching model is suitable to predict the etched shape, and that the importance of precise alignment becomes large as beam quality factor becomes larger.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.213-216
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• 2007

LGP (light guide plate) of LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of the major components which affects the product quality of LCD. In the present study, the optical patterns of LGP(2.2") are manufactured by three different methods, namely, laser ablation, chemical etching and LiGA - reflow, respectively. The pattern surface images and roughness of mold and product were compared to check the optical characteristics. From the results of measurement the optical patterns fabricated by LiGA - reflow method showed the best geometric structure as intended in design and the lowest roughness among those.