• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1572-1577
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• 2003

High-power pulsed laser ablation under atmospheric pressure is studied utilizing numerical and experimental methods with emphasis on recondensation ratio, and the dynamics of the laser induced vapor flow. In the numerical calculation, the temperature pressure, density and vaporization flux on a solid substrate are first obtained by a heat-transfer computation code based on the enthalpy method, and then the plume dynamics is calculated by using a commercial CFD package. To confirm the computation results, the probe beam deflection technique was utilized for measuring the propagation of a laser induced shock wave. Discontinuities of properties and velocity over the Knudsen layer were investigated. Related with the analysis of the jump condition, the effect of the recondesation ratio on the plume dynamics was examined by comparing the pressure, density, and mass fraction of ablated aluminum vapor. To consider the effect of mass transfer between the ablation plume and air, unlike the most previous investigations, the equation of species conservation is simultaneously solved with the Euler equations. Therefore the numerical model computes not only the propagation of the shock front but also the distribution of the aluminum vapor. To our knowledge, this is the first work that employed a commercial CFD code in the calculation of pulsed ablation phenomena.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2163-2165
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• 2005

A pulsed laser ablation deposition (PLAD) technique has been used for producing fine particle as well as thin film at relatively low substrate temperatures. However, in order to manufacture and evaluate such materials in detail, motions of plume particles generated by laser ablation have to be understood and interactions between the particles by ablation and gas plasma have to be clarified. Therefore, this paper was focused on the understanding of plume motion in laser ablation assisted by Ar plasma at 50(mTorr). Two-dimensional hybrid model consisting of fluid and particle models was developed and three kinds of plume particles which are carbon atom (C), ion $(C^+)$ and electron were considered in the calculation of particle method It was obtained that ablated $C^+$ was electrically captured in Ar plasmas by strong electric field (E). The difference between motions of the ablated electrons and $C^+$ made E strong and the collisional processes active.

• Journal of The Korean Radiological Technologist Association
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• v.29 no.1
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• pp.210-210
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• 2003

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.737-742
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• 2012

To evaluate efficacy of microwave ablation in a primary clinical study, sixty patients (44 men, 16 women; mean age 53 years) with 96, 1-8 cm (mean $3.20{\pm}0.17$ cm) liver cancers were treated with 2,450-MHz internally cooled-shaft antenna. Complete ablation (CA) and local tumor progression (LTP) rates as well as complications were determined. CA rates in small (< 3.0 cm), intermediate (3.1-5.0 cm) and large (5.1-8.0 cm) liver cancers were 96.4% (54/56), 92.3% (24/26) and 78.6% (11/14), respectively. During a mean follow-up period of $17.17{\pm}6.52$ months, LTP occurred in five (5.21%) treated cases. There was no significant difference in the CA and LTP rates between the HCC and liver metastasis patient subgroups (P<0.05). Microwave ablation provides a reliable, efficient, and safe technique to perform hepatic tumor ablation.

• Knee surgery & related research
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• v.30 no.4
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• pp.348-355
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• 2018

Purpose: To evaluate the clinical effects of using anatomical bony landmarks (Parsons' knob and the medial intercondylar ridge) and minimal ablation of the tibial footprint to improve knee anterior instability and synovial graft coverage after double-bundle anterior cruciate ligament reconstruction. Materials and Methods: We performed a retrospective comparison of outcomes between patients who underwent reconstruction with minimal ablation of the tibial footprint, using an anatomical tibial bony landmark technique, and those who underwent reconstruction with wide ablation of the tibial footprint. Differences between the two groups were evaluated using second-look arthroscopy, radiological assessment of the tunnel position, postoperative anterior knee joint laxity, and clinical outcomes. Results: Use of the anatomical reference and minimal ablation of the tibial footprint resulted in a more anterior positioning of the tibial tunnel, with greater synovial coverage of the graft postoperatively (p=0.01), and improved anterior stability of the knee on second-look arthroscopy. Both groups had comparable clinical outcomes. Conclusions: Use of anatomical tibial bony landmarks that resulted in a more anteromedial tibial tunnel position improved anterior knee laxity, and minimal ablation improved synovial coverage of the graft; however, it did not significantly improve subjective and functional short-term outcomes.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.401-405
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• 1994

The chemical composition and electrical properties were investigated for epitaxially crystallized $(Ba_{0.5}Sr_{0.5})Tio_3$ (BST) films deposited on Pt and $YBa_Cu_3O_{7-x}$(YBCO) electrodes by laser ablation technique. The crystalline quality of the heteroepitaxial BST films deposited on Pt bottom electrode was found to be better than that of BST film on YBCO electrode by the RBS analysis. Films deposited at $600^{\circ}C$ on Pt electrode showed a dielectric constant of 320 and a dissipation factor of 0.023 at 100kHz. Leakage current density of BST films on Pt electrode was smaller than that on YBCO bottom electrode. Their leakage current density was about 0.8$\mu \; A/ \textrm{cm}^2$ at an applied electric field of 0.15MV/cm.

• Archives of Plastic Surgery
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• v.36 no.2
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• pp.205-210
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• 2009

Purpose: Corrugator supercilii muscle pulls eyebrow to inferomedial direction and produces the vertical component of the glabellar line formation. Current techniques for eliminating of glabellar frown include direct resection of corrugators and botulinum toxin injection. Muscle resection in endoscopic face lift procedure is relatively complex and has many disadvantages ranging from possible nerve injury, postoperative edema, pain and a long recovery period. The Botox treatment on the other hand is much more simple in technique but has a short duration of action. The authors have attempted new ways of finding improved treatment of the glabellar frown by selectively blocking of motor nerves innervating the corrugator supercili muscle by using radiofrequency ablation technique. Methods: A total of 80 patients were recruited in our study during the period between Feb. 2007 to June 2008. A probe was introduced from the supraorbital ridge and advanced to the corrugator supercilii muscle. Nerve stimulator was then used to locate the nerve innervating the corrugator and radiofrequency ablation of the nerve was done. Results: In all patients, there were marked improvement in glabellar frown after treatment. There were no reported cases of any relapses during the follow up period. No complication was noted such as facial nerve injury. No patient complained of any adverse symptoms other than slight discomfort due to swelling of the operation site. Conclusion: The treatment of glabellar frown lines using selective nerve block with radiofrequency ablation was not only less invasive but also excellent in surgical outcomes.

• Korean Journal of Radiology
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• v.22 no.6
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• pp.944-950
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• 2021

Objective: To demonstrate the feasibility of percutaneous microwave ablation in desmoid fibromatosis with respect to tumor volume control and improvement in the quality of life. Materials and Methods: Twelve microwave ablations were performed in 9 patients with a histological diagnosis of desmoid fibromatosis between January 2010 and January 2019. The study population included 6 female and 3 male, with an age range of 21-76 years (mean = 46.6 years; standard deviation [SD] = 19.3 years). The mean major axis of the tumors was 10.9 cm (SD = 5.2 cm) and mean lesion volume was 212.7 cm³ (SD = 213 cm³). Their anatomical distribution was as follows: 3 lesions in the thigh, 2 in the gluteus, 2 in the leg and 2 in the periscapular region. We evaluated the reduction in tumor volume and improvement in the quality of life based on the Eastern Cooperative Oncology Group (ECOG) scale. Results: An average tumor volume reduction of 70.4% (SD = 24.9) was achieved, while the quality of life (ECOG scale) improved in 88.9% of patients. Conclusion: Percutaneous microwave ablation may potentially be a safe, effective, and promising technique for controlling tumor volume and improving the quality of life in patients with desmoid fibromatosis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.433-438
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• 2009

The main objective of this research effort is to develop the performance of C/SiC composites manufactured by LSI (Liquid Silicon Infiltration) method for solid and liquid rocket propulsion system and ensure the performance analysis technique. The high performance and reliability of C/SiC composite are proved for solid and liquid rocket propulsion system. And the performance analysis technique related to mathematical ablation model is originated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1847-1853
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• 2000

A computer simulation technique for 2-dimensional laser generated ultrasonic waves was developed for visualization and investigation of ultrasonic propagation in solids. The technique is similar to a finite difference method (FDM) and a mass-particle model method, but uses a new nodal calculation method based on fundamental consideration of an elastic wave equation. By this method, the propagation behavior oflaser generated ultrasonic wave in thermoelastic and ablation mode is visualized and shows good agreement with previous experimental result or the numerical analysis result by Green function.