• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.251-254
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• 2006

In this paper, cutting qualifies and fracture strength of silicon dies by laser dicing are investigated. Laser micromachining is the non-contact process using thermal ablation and evaporation mechanisms. By these mechanisms, debris is generated and stick on the surface of wafer, which is the problem to apply laser dicing to semiconductor manufacture process. Unlike mechanical sawing using diamond blade, chipping on the surface and crack on the back side of wafer isn't made by laser dicing. Die strength by laser dicing is measured via the three-point bending test and is compared with the die strength by mechanical sawing. As a results, die strength by the laser dicing shows a decrease of 50% in compared with die strength by the mechanical sawing.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.5-8
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• 2013

The ignition of aluminum particles under high pressure and temperature conditions is studied. The laser ablation method is used to generate aluminum particles exposed to pressures ranging between 0.35 and 2.2 GPa. A continuous wave $CO_2$ laser is then used to heat surface of the aluminum target until ignition is achieved. We confirm ignition by a spectroscopic analysis of AlO vibronic band of 484 nm wavelength. The radiant temperature is measured with respect to various pressures for tracing of required heating energy for ignition. Then the ignition temperature is deduced from the radiant temperature using the thermal diffusion equation. The established ignition criteria for corresponding temperature and pressure can be used in the modeling of detonation behavior of heavily aluminized high explosives or solid propellants.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1256-1258
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• 1993

Optical data storage offer high density storage and archival storage capability. In this study, we selected the ablation mechanism-one of an irreversible recording system-using the antireflection trilayer(ART) structure. Optical recording medium is a $(Te_{86}Se_{14})_{50}Bi_{50}$ thin films. Actually, ART structure is fabricated and compared to monolayer structure. ART structure leads to the reduction of recording power as well as an increase in the effciency compared to the monolayer structure.

• Journal of Chest Surgery
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• v.54 no.1
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• pp.75-78
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• 2021

Minimally invasive cryoablation is often considered for lung tumor patients with high surgical risk or inoperable metastatic lung tumors. Cryoablation is a type of thermal percutaneous ablation in which argon and helium gases are delivered via a cryoprobe to induce tissue freezing and necrosis. We report the case of a 23-year-old woman who had suffered from multiple pulmonary endometriosis with frequent intermittent hemoptysis during menstruation for 6 years prior to her visit. She was treated with cryoablation at our hospital, and since her treatment, she has been doing well with no hemoptysis for at least 6 months. Although endometriosis is a benign lung disease, cryoablation is an ideal and effective treatment option for patients with multiple endometriosis.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.469-475
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• 2008

Background: Video-assisted thoracic sympathicotomy is a definitive minimally invasive treatment for axillary hyperhidrosis. Different techniques exist for controlling axillary hyperhidrosis, but they are temporary and expensive. We compared the results after using two different levels of sympathicotomy for treating axillary hyperhidrosis: T3-T4 and T4. Material and Method: Between June 2002 and May 2007, 30 patients with isolated axillary hyperhidrosis underwent either T3-T4 or T4 thoracoscopic sympathicotomy in the Department of Thoracic & Cardiovascular Surgery at Wonkwang University Hospital. The patients were divided into two groups. Group I (n=15) was composed of patients who underwent T3-T4 sympathicotomy (thermal ablation), and Group II (n=15) was composed of patients who underwent T4 sympathicotomy (thermal ablation). The procedures were bilateral and simultaneous, involving the use of two 2-mm trocars and a 0-degree 2-mm thoracoscope under general anesthesia with single endotracheal intubation. Outcome parameters included satisfaction rate of treatment, degree of compensatory sweating, and postoperative complications. Patients were interviewed by telephone regarding satisfaction and compensatory hyperhidrosis. Result: There were no differences in age between group I and group II. The mean follow-up for the T3-T4 group was $38.7{\pm}2.3$ months, and the mean follow-up for the T4 group was $18.7{\pm}3.6$ months. The immediate therapeutic success rate (within 2 weeks postoperative) was 100% in both groups, and there were no recurrences in either group during the long-term follow-up period. The satisfaction rate was higher (93.3%) in the T4 group than in the T3-T4 group (53.3%), and the incidence of compensatory hyperhidrosis was lower in the T4 group (6.7%) than in the T3-T4 group (46.7%). Postoperative complications included one mild pneumothorax and two instances of intercostal neuralgia. Digital infrared thermographic imaging (DITI) correlated well with postoperative satisfaction. Conclusion: Both techniques proved effective for controlling isolated axillary hyperhidrosis. The T4 group had a higher satisfaction rate and lower severity of compensatory hyperhidrosis. Hence, thermal ablation of the lower interganglionic fibers of the third thoracic sympathetic ganglion on the fourth rib is a more practical and minimally invasive treatment than is the T3-T4 surgical method, according to the degree of compensatory sweating in isolated axillary hyperhidrosis.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.21-27
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• 2019

Cellulose-based carbon fabrics are used in aerospace nozzles have low thermal conductivity and high ablation resistance. However, there is a disadvantage in that the weight is reduced by 70~90% in the pyrolysis process and graphitization process and the residual rate is low when the final carbon fabric is produced. In this study, phosphoric acid as a phosphorus flame retardant and Citric acid as a cross-linking agent were treated on the lyocell fabrics. After that the functional groups were identified and thermal properties were confirmed by FT-IR, XRD and TGA. The yields of the final carbon fabrics were also compared through the pyrolysis and graphitization process. The graphitized yield increased to 8.1% with increasing citric acid to 16 wt% added.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.699-705
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• 2011

High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.6980-6985
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• 2014

A micro-conductive pattern was fabricated on an insulating substrate ($SiO_2$) surface using a laser direct writing method. In the LIFT process, when the laser beam irradiates a thin metal film, the photon energy is absorbed by the film and converted to thermal energy, and the thermal decomposition reaction produced by the resulting heat conduction forms a deposit on the substrate. The resistivity of the micro-electrodes deposited through LIFT process with and without polymer coating was measured. The results showed that the electric conductivity of the micro-pattern and micro-structure can be increased approximatly two times when the deposited micropattern is fabricated through a LIFT process with a polymer coating, compared to the case without a polymer coating.

• Medical Lasers
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• v.8 no.1
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• pp.13-18
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• 2019

Background and Objectives High-intensity focused ultrasound (HIFU) can produce small zones of thermal damage. A HIFU procedure is non-invasive and it can achieve rejuvenation of facial skin. Fractional CO₂ laser resurfacing delivers thermal damage to the pixilated columnar zone of the skin and so evoke collagen remodeling, the same as HIFU. In many cases, the patients who want rejuvenation with HIFU are also good candidates for cutaneous photorejuvenation such as can be accomplished via fractional CO₂ resurfacing. If patients are treated in a single session by remodeling both the superficial and deep compartments of skin by using both modalities, then improvement in rhytides and tightening of sagging skin will optimize the aesthetic result. Materials and Methods Between May 2014 and January 2018, a total of 44 patients were treated with combination HIFU and fractional CO₂ laser resurfacing according to our protocol. First, the HIFU was applied to the entire face with an average of 300 treatment lines. Immediately after HIFU treatment, the ultrasound gel was washed off and then fractional CO₂ laser resurfacing was performed. We evaluated the patients using 4-point grading scales. The clinician examined the skin for evidence of complications after the completion of treatment. Results All the patients' skin quality showed improvement. Further. the clinical results after duel modality treatment were substantially better than that after the use of either modality alone. The recovery times and the incidence of adverse events when quickly and consecutively performing both treatments were similar as compared to those with employing stepwise treatment. We encountered no complications whatsoever. Conclusion When compared with stepwise therapy, combination therapy with HIFU and fractional CO₂ resurfacing offers better, safer and more effective clinical results. Thus, for targeting multiple layers of aging facial skin, this combination therapy can be safely performed in a single treatment session.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.120-120
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• 2003

The metallic oxide nanomaterials including ZnO, Ga$_2$O$_3$, TiO$_2$, and SnO$_2$ have been synthesized by a number of methods including laser ablation, arc discharge, thermal annealing procedure, catalytic growth processes, and vapor transport. We have been interested in preparing the nanomaterials of Ga$_2$O$_3$, which is a wide band gap semiconductor (E$_{g}$ =4.9 eV) and used as insulating oxide layer for all gallium-based semiconductor. Ga$_2$O$_3$ is stable at high temperature and a transparent oxide, which has potential application in optoelectronic devices. The Ga$_2$O$_3$ nanoparticles and nanobelts were produced using GaN single crystals, which were grown by flux method inside SUS$^{TM}$ cell using a Na flux and exhibit plate-like morphologies with 4 ~ 5 mm in size. In these experiments, the conventional electric furnace was used. GaN single crystals were pulverized in form of powder for the growth of Ga$_2$O$_3$ nanomaterials. The structure, morphology and composition of the products were studied mainly by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM).).