• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.311-317
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• 2005

It has been the most progressive interruption technique to use the ablation gas from the surface of PTFE nozzle driven by arc plasma during switching process in $SF_6$ gas circuit breakers. This advanced interruption technique can reduce the required mechanical energy to compress and blow the gas for extinguishing the arc plasma between the electrodes due to using the ablation effect instead. In order to consider the phenomena during calculation of switching process, it is required to confirm the principles of ablation from PTFE nozzle as well as of arc plasma during switching process. In this study, we have calculated the switching process considered the ablation of PTFE nozzle driven by arc plasma using multidisciplinary simulation technique and compared the results with the data without the ablation effect. More $50\%$ difference of pressure rise inside expansion chamber has been found from the results and it should be indispensable for this type of computational work to consider and include the ablation effect of PTFE nozzle. Further study on turbulence and radiation will be followed.

• Korean Journal of Radiology
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• v.1 no.4
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• pp.175-184
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• 2000

Although surgical resection remains the best option as potentially curative therapy for hepatocellular carcinoma, radiofrequency thermal ablation has begun to receive much attention as an effective minimally invasive technique for the local control of unresectable malignant hepatic tumors. Most recent radiofrequency devices equipped with a powerful generator and larger needle electrode permit larger thermal lesions, up to 5 cm in diameter, with a single ablation. In this article, the author reviews the technical developments and early clinical results obtained with radiofrequency ablation techniques.

• Journal of Aerospace System Engineering
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• v.15 no.6
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• pp.10-18
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• 2021

A flame deflector prevents a launch system from thermal damage by deflecting the exhaust flame of the launch vehicle. During the deflection of the flame, the flame deflector is subjected to a high-temperature and high-pressure flow, which results in thermal ablation damage at the surface. Predicting this ablation damage is an essential requirement to ensure a reliable design. This paper introduces a numerical method for predicting the ablation damage phenomena based on a one-way fluid-structure interaction (FSI) analysis. In the proposed procedure, the temperature and convective heat transfer coefficient of the exhaust flame are calculated using a fluid dynamics analysis, and then the ablation is calculated using a finite element analysis (FEA) based on the user-subroutine UMESHMOTION and Arbitrary Lagrangian-Eulerian (ALE) adaptive mesh technique in ABAQUS. The result of such an analysis was verified by comparison to the ablation test result for a flame deflector.

• Laser Solutions
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• v.11 no.1
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• pp.12-18
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• 2008

Laser micromachining is a promising technique to fabricate the micro-scale devices. However, there remains important challenges to reducethe redeposition of ablated materials around the laser irradiated zone and to get a smooth surface, especially for metal and semiconductor materials. To achieve the high-quality micromachined devices, various methods have been developed. Liquid-assisted micromachining can be a good solution to overcome the previously mentioned problems. During the laser ablation process, the liquid around the solid sample dramatically changes the ablation characteristics, such as ablation rate, surface profile, formation of debris, and so on. In this investigation, we conducted the laser micromachining of Si in various liquid environmental conditions, such as liquid types, liquid thickness. In addition, using nanoscale time-resolved shadowgraphy technique, we observed the ablation process in liquid environments to understand the mechanism of liquid-assisted laser micromachining.

• International Journal of Arrhythmia
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• v.19 no.3
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• pp.235-284
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• 2018

In this part the writing group will cover strategies, techniques, and endpoints of atrial fibrillation (AF) ablation. Prior to all, electrical isolation of the pulmonary veins is recommended during all AF ablation procedures. In addition, techniques to be used for ablation of persistent and long-standing persistent AF, adjunctive ablation strategies, nonablative strategies to improve outcomes of AF ablation, and endpoints for ablation of paroxysmal, persistent, and long-standing persistent AF will be reviewed. Currently many technologies and tools are employed for AF ablation procedures. Radiofrequency energy, cryoablation, and other energy sources and tools are in various stages of development and/or clinical investigation. Finally, anticoagulation strategies pre-, during, and postcatheter ablation of AF and technical aspects of ablation to maximize safety are discussed in this section.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.634-639
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• 2002

Using laser ablation technique carbon thin films were deposited on Si(100) substrate as a function of substrate temperature. In this study, the surface morphologic, structural and field emission properties of these carbon thin films were investigated using Raman spectroscopy, scanning electron microscopy, and a diode technique, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover, the intensity of D-band and the full width at half maximum of these bands were dependent on substrate temperatures. As the substrate temperature was increased, the field emission properties were improved. As the result, we find that the field emission properties of the films were changed significantly with the substrate temperature and structural features of carbon than films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.484-487
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• 2001

Amorphous carbon thin films were deposited using laser ablation technique on Si(100) substrates at different temperatures. In this study, effects of the substrate temperature on the properties of amorphous carbor, films were systematically investigated. The surface morphologic and structural properties of the films were studied by scanning electron microscopy (SEM) and raman spectroscope, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover the intensity ratio of D-band and G-band and the full width at half maximum of these bands were dependent on substrate temperatures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.484-487
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• 2001

Amorphous carbon thin films were deposited using laser ablation technique on Si(100) substrates at different temperatures. In this study, effects of the substrate temperature on the properties of amorphous carbon films were systematically investigated. The surface morphologic and structural properties of the films were studied by scanning electron microscopy (SEM) and raman spectroscope, respectively. With increasing of the substrate temperature, the surface morphologies were changed singnificantly. Moreover the intensity ratio of D-band and G-band and the full width at half maximum of these bands were dependent on substrate temperatures.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.2
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• pp.76-86
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• 2022

Ovarian cystectomy is the preferred technique for the surgical management of ovarian endometrioma. However, other techniques such as ablation or sclerotherapy are also commonly used. The aim of this review is to summarize information regarding the efficacy of ablation and sclerotherapy compared to cystectomy in terms of ovarian reserve, the recurrence rate, and the pregnancy rate. Several studies comparing ablation versus cystectomy or sclerotherapy versus cystectomy in terms of the serum anti-Müllerian hormone (AMH) decrement, endometrioma recurrence, or the pregnancy rate were identified and summarized. Both ablation and cystectomy have a negative impact on ovarian reserve, but ablation results in a smaller serum AMH decrement than cystectomy. Nonetheless, the recurrence rate is higher after ablation than after cystectomy. More studies are needed to demonstrate whether the pregnancy rate is different according to whether patients undergo ablation or cystectomy. The evidence remains inconclusive regarding whether sclerotherapy is better than cystectomy in terms of ovarian reserve. The recurrence rates appear to be similar between sclerotherapy and cystectomy. There is not yet concrete evidence that sclerotherapy helps to improve the pregnancy rate via in vitro fertilization in comparison to cystectomy or no sclerotherapy.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.11-20
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• 2021

Decontamination of systems, structures and components (SSC) during the decommissioning of a Nuclear Power Plant (NPP) can be for a variety of reasons. The main reasons for decontamination are: to reduce the contamination of SSC to a reasonably low level, to reduce the potential for the spread of contaminants into the environment and to reduce the cost of disposal due to the reduced level of contamination in a particular SSC. The decontamination technique can be aggressive or non-aggressive depending on the intent after the decontamination process. Aggressive decontamination technique is used when the intent is not to reuse the SSC while a non-aggressive decontamination technique is used with the intent of SSC reuse. For different SSCs there are different decontamination techniques that can be used, each having its own advantages and drawbacks. Metal components such as pipes in the nuclear power plant account for a large amount of nuclear wastes generated. Some of these wastes can be reused if the contaminant level is reduced to an acceptable level. Laser ablation is a non-aggressive decontamination technique that can be used to reduce the contamination in pipes to an acceptable level with no secondary waste generated during the process. The operation and control of a laser ablation device must be precise to achieve a high decontamination factor. This precision can be achieved by a well-designed motion control system. For this purpose, a motion control system was developed consisting of two parts: the first part being the precise control of the laser ablation device inside the pipe and the second part is the control of the laser ablation device outside the pipe. This paper describes the Systems Engineering approach for the development process of a motion control system for the Laser decontamination system.