• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.98-105
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• 2008

In this paper, the system for monitoring process of aluminum laser welding was developed using the light signal emitted from the plasma which comes from interaction between material and laser. Photodiode for monitoring system was selected based on the spectrum analysis of light from plasma and keyhole. Behavior of plasma and keyhole was analyzed through the sensor signals. Value of sensor signal represented the light intensity and fluctuation of signal indicated the stability of plasma and keyhole. For the relation between welding condition and sensor signals, the input power and weld geometry greatly effected on the average of each sensor signals. Using the feature values of signals, estimation model for tensile strength of weld was formulated with neural network algorithm. Performance of this model was verified through coefficient of determination and average error rate.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.135-137
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• 2006

To improve device yield and throughput, faults in plasma processing equipment should be quickly and accurately diagnosed. Despite many useful information of ex-situ sensor measurements, their applications to recognize plasma faultshave not been investigated. In this study, a new technique to identify fault causes by recognizing X-ray photoelectron spectroscopy (XPS) using neural network and continuous wavelet transformation (CWT). The presented technique was evaluated with the plasma etch data. A totalof 17 experiments were conducted for model construction. Model performance was investigated from the perspectives of training error, testing error, and recognition accuracy with respect to various thresholds. CWT-based BPNN models demonstrated a higher prediction accuracy of about 26%. Their advantages over pure XPS-based models were conspicuous in all three measures at small networks.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.96-98
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• 2006

A new ex-situ model to diagnose a plasma processing equipment was presented. The model was constructed by combining wavelet, scanning electron microscope, ex-situ measurement of etching profile, and neural network. The diagnosis technique was applied to a tungsten etching process, conducted in a $SF_6$ helicon plasma. The wavelet was used to characterize detailed variations of plasma-etched surface. The diagnosis model was constructed with the vertical wavelet component. For comparison, a conventional model was built by using the estimated profile data. Compared to the conventional model, the wavelet-based model, demonstrated a much improved diagnosis.

• Journal of Welding and Joining
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• v.19 no.4
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• pp.375-378
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• 2001

The new development of the surface hardening technology has been attracted to machine designer and materials scientist in the view point of improvement in the lifetime and performance of the machine. The heat-treatment process has been a well-known technology to make harden the metal surface despite of its inefficiency in productivity and its inherent environmental pollution problem. Therefore, the plasma technology has been applied to the conventional process to improve the above issues and become successful in diminishing the ecological harmfulness. However, the drastic short processing time has been sought to increase the productivity by means of new plasma technology so-called, high temperature pulsed plasma flux (HTPPF). The basic principle and features of this HTPPF will be introduced and the present status of this technology will be described in this paper.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.203-203
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• 2013

Low pressure plasmas play a key role in many areas including electronic, aerospace, automotive, biomedical, and toxic waste management industries, and the advantages of the plasma are well known the processing procedure is established. However, the insight behavior of the discharges remains a mystery, even though a simple geometry as capacitive discharges. In this work, we measured RF power dissipation in capacitively coupled plasma (CCP) at various experiment conditions with potential probe and RF current probe. Through the results, we will have a clearer view of the inner nature of the CCP.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.244-245
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• 2007

The RF inductive discharge of inductively couples plasma (ICP) continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. Although most practical ICPs operate at 13.56 [MHz] and 2.65 [MHz], the trend to reduce the operating frequency is clearly recognizable from recent ICP developments. in and electrodeless fluorescent lamp, the use of a lower operating frequency simplifies and reduces cost of RF matching systems and RF generators and can eliminate capacitive coupling between the inductor coil and plasma, which could be a strong factor in wall erosion and plasma contamination. In this study, electric and optical characteristics of electrodeless fluorescent lamp by changing ferrite position is discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.3
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• pp.515-520
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• 2009

In this paper, the monitoring system was developed measuring the light signal emitted from the plasma in aluminum laser welding. Spectrum of plasma was measured using a spectrometer, and the photodiode was selected based on the spectrum analysis. The sensor signals for various welding conditions could be obtained, the characteristic of signal was closely related to the intensity and stability of plasma through mean value of signal and FFT analysis. The reason of signal fluctuation was behavior of plasma and keyhole and it was also connected with the surface bead shape of weld.

• Textile Coloration and Finishing
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• v.34 no.3
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• pp.165-172
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• 2022

Polypropylene(PP) is a textile material with various functions such as eco-friendliness, lightness, and elasticity. Although most synthetic fibers can be dyed and finished, but original PP is difficult to dye or finish due to its extremely hydrophobic properties, so its application expansion is limited. In order to solve this problem, dyeable PP was developed, and various researches on textiles for clothing such as mass production technology, fine fiberization and performance improvement are in progress. Plasma treatment is a processing method for modifying the surface of fabrics, and has effects such as hydrophilization, deepening color, improving adhesion, and surface polymerization. In this study, plasma treatment was applied to study changes in hydrophilization properties of dyeable PP, surface changes before and after plasma treatment and performance according to hydrophilization.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.185-192
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• 2020

In this study, materials characterization of pure copper and copper based carbon nano-tube composite prepared by powder metallurgy method were investigated. Prior to evaluate materials characterization, spark plasma sintering processing variables such as sintering temperature, pressure, thickness and diameter of compacts was optimized to ensure the microstructure and materials property of pure Cu and Cu-CNT composite. In addition, corrosion behavior of Cu-based CNT composite produced by powder sintering method was investigated. It was confirmed from this study that the corroded surfaces of the composite shows less dissolution compared with pure copper in 3.5 wt% NaCl solution. The measured corrosion current density (I_corr) indicates improved corrosion property of Cu based composite containing small additions of CNTs in chloride containing media. Micro-galvanic activity between Cu and CNT was not observed in given sintering condition.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.760-765
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• 1996

Silicon oxide thin films are prepared by plasma-enhanced CVD (PECVD) using 100kHz and 13.56MHz generators. Source gases are two sorts of mixture, tetramethoxysilane (TMOS) and oxygen, and tetramethylsilane (TMS) and oxygen. We investigate the effect of frequency on film properties of deposited films including mechanical properties. 100kHz PECVD process can deposit silicon oxide films at $23^{\circ}C$ at the power of 20W. X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and ellipsometric measurements reveal that the structural quality of the films prepared both by 100kHz process and by 13.56MHz process are very like silicon dioxide. The 100kHz process is adequate for low temperature deposition of SiOx films.