• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.16-20
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• 2003

Objectives: Radiotherapy is an effective treatment in the initial management of T1 glottic carcinoma, but local recurrent or residual tumor growth is found in approximately 10% of the patients. Even in recurrence or residual tumor, in highly selected cases, conservation surgery with preservation of a portion of the larynx is feasible. So we investigated the efficacy of salvage vertical partial laryngectomy for recurrent glottic carcinoma after irradiation. Material and Methods: Retrospectively we reviewed a consecutive series of 10 patients treated by conservative vertical partial laryngectomy of the larynx for radiation-failure, recurrent T1 glottic squamous cell carcinoma treated at Severance Hospital from 1994 to 2002. Results: Local recurrence developed in 4 patients (40%). Two patient was salvaged by further totallaryngectomy. Successful salvage was achieved finally in 8 (80%) of the 10 patients. There was no operative mortality. Postoperative perichondritis was developed in two patients. One was resolved by conservative treatment, but the other has underwent the total laryngectomy. Conclusion: A vertical partial laryngectomy in case of recurrent glottic carcinoma after a course of irridation should be the therapy of choice when stringent criteria are observed.

• CELLMED
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• v.11 no.1
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• pp.6.1-6.7
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• 2021

In situ gelling devices, as they enter the body, are dosage forms in the shape of the sol but turn into gel types under physiological circumstances. Transition from sol to gel is contingent on one or a mixture of diverse stimuli, such as transition of pH control of temperature, irradiation by UV, by the occurrence of certain ions or molecules. Such characteristic features may be commonly employed in drug delivery systems for the production of bioactive molecules for continuous delivery vehicles. The technique of in situ gelling has been shown to be impactful in enhancing the potency of local or systemic drugs supplied by non-parenteral pathways, increasing their period of residence at the absorption site. Formulation efficacy is further improved with the use of mucoadhesive agents or the use of polymers with both in situ gelling properties and the ability to bind with the mucosa/mucus. The most popular and common approach in recent years has provided by the use of polymers with different in situ gelation mechanisms for synergistic action between polymers in the same formulation. In situ gelling medicine systems in recent decades have received considerable interest. Until administration, it is in a sol-zone and is able to form gels in response to various endogenous factors, for e.g elevated temperature, pH changes and ions. Such systems can be used in various ways for local or systemic supply of drugs and successfully also as vehicles for drug-induced nano- and micro-particles. In this review we will discuss about various aspects about use of these in situ gels as novel drug delivery systems.

• Journal of Periodontal and Implant Science
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• v.52 no.1
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• pp.39-53
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• 2022

Purpose: This study evaluated the systemic and local effects of doxycycline (DOX) and low-intensity laser (LIL) treatment as adjuvants to scaling and root planing (SRP) in the treatment of experimental periodontitis in rats. Methods: The sample consisted of 180 male rats (Rattus norvegicus albinus, Wistar), of which 30 did not receive induction of periodontal disease (negative control [NC] group) and 150 received induction of periodontal disease in the lower first molar. After 7 days, the ligature was removed, and the animals were divided into the following groups: NT (no treatment), SRP (SRP), DOX (SRP and DOX irrigation), LIL (SRP and laser irradiation), and DOX+LIL (SRP, DOX, and LIL). The animals were euthanized at 7, 15, and 30 days; thereafter, biochemical, radiographic, histological, and immunohistochemical analyses were performed. Results: In the intragroup analysis, lower concentrations of α-1-glycoprotein acid (α-1-Ga) and complement 3 (C3) were observed in the DOX+LIL group than in all other groups at all time points, as well as lower levels of complement 4 (C4) at 15 and 30 days (P<0.001). Less bone loss was observed in the DOX, LIL, and DOX+LIL groups than in the NC and SRP groups at all time points (P<0.001). There was a smaller number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the DOX+LIL group than in the other groups at all time points (P<0.001). Positive correlations were observed between the systemic levels of α-1-Ga, C3, and C4 and the number of TRAP-positive cells. Conclusions: The combination of DOX with LIL as SRP adjuvants was effective both systemically and locally for the treatment of experimental periodontitis in rats.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.95-99
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• 2001

Purpose : To evaluate the effectiveness and tolerance of postoperative external radiotherapy for patients with intracranial meningiomas. Materials and Methods : The records of thirty three patients with intracranial meningiomas who were treated with postoperative external irradiation at our institution between Feb, 1988 and Nov, 1999 were retrospectively analyzed. Median age of patients at diagnosis was 53 years with range of 17 to 68 years. Sites of involvement were parasagital, cerebral convexity, sphenoid ridge, parasellar and tentorium cerebelli. Of 33 evaluated patients, 15 transitional, 10 meningotheliomatous, 4 hemangiopericytic, 3 atypical and 1 malignant meningioma were identified. Four patients underwent biopsy alone and remaining 29 patients underwent total tumor resection. A dose of 50 to 60 Gy was delivered in 28-35 daily fractions over a period of 5 to 7 weeks. Follow-up period ranged from 12 months to 8 years. Results : The actuarial survival rates at 5 and 7 years for entire group of patients were 78% and 67%, respectively. The corresponding disease free survival rates were 73% and 61%, respectively. The overall local control rate at 5 years was 83%. One out of 25 patients in benign group developed local failure, while 4 out of 8 patients in malignant group did local failure (p<0.05). Of 4 patients who underwent biopsy alone, 2 developed local failure. There was no significant difference in 5 year actuarial survival between patients who underwent total tumor resection and those who did biopsy alone. Patients whose age is under 60 showed slightly better survival than those whose age is 60 or older, although this was not statistically significant. There was no documented late complications in any patients. Conclusion : Based on our study, we might conclude that postoperative external beam radiotherapy tends to improve survival of patients with intracranial meningiomas comparing with surgery alone.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.73-79
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• 1991

Between January 1980 and September 1988,08 patients with advanced T3 & T4 glottic carcinoma were treated with RT and surgery/RT in the Department of Radiation Oncology, Yonsei Cancer Center and ENT, Yonsei University College of Medicine. The mean age was 60 years old (range 33 to 79 years old). The 34 patients were treated with irradiation alone, and the remaining 34 patients with surgery and irradiation. Initial nodal presentation was $37\% (25/68);\;31\%$ (l1/34) in RT alone group and $41\%$ (14/34) in combined treatment group. The minimum follow-up was 2 years. The local control rate after treatment was $47\%$ in RT alone group and $65\%$ in combined treatment group; $57\%$ for node negative and $27\%$ for node positive patients treated with RT alone; $65\%$ for node negative and $54\%$ for node positive patients treated with combined treatment. The treatment failure was observed in 30 patients; 14 patients for primary local failure, 6 patients for regional nodal failure,5 patients for local and regional failure, 26 patients for primary failure and/or distant metastasis, and 2 patient for regional failure and/or distant metastasis. The overall 5-year suwival rate was $57\%;\;37\%$ in RT alone group and $70\%$ in combined treatment group; $55\%$ for node negative and $20\%$ for node positive patients treated with RT alone; $73\%$ for node negative and $77\%$ for node positive patients treated with combined treatment. In conclusion, the combined treatment groups in the treatment of advanced 73 and 74 glottic cancer showed the better results in local control rates and S-year actuarial survival rates than RT alone group. We suggest that total laryngectomy and postoperative RT in the most patients of advanced glottic cancer were performed. However, in cases of node negative patints, RT alone is prefer as a treatment modality over combined surgery and RT since the treatment results were comparable and furthermore functional preservation could be achieved.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.322-329
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• 2009

Machinability of LAM(Laser Assisted Machining) has been studied for ceramics such as $Al_2O_3$, $Si_3_N4$ and $ZrO_2$ by $CO_2$ laser. It was possible to remove ceramics by PCBN tool because material became softening and deterioration by local laser beam irradiation. The advantage of LAM is the ability to produce larger material removal rates and tool life. But, for cutting of $Al_2O_3$ and $ZrO_2$, stage of laser power control was needed owing to thermal shock with high temperature of workpiece by laser power. And when $Si_3N_4$ was machined by LAM, $N_2$ gas spouted from surface of one cause of high temperature. Characteristics of LAM were analyzed using pyrometer, dynamometer, SEM and EDS to measure temperature of workpiece surface, cutting force, variation of machining surface and structure of lattice respectively. As the result of this study, it was found that machinability of LAM for ceramics in $CO_2$ laser and mechanism of LAM was different according to the kind of ceramics because of properties of materials.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1213-1218
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• 2004

The present article reports extensive numerical results on the non-local characteristics of ultra-short pulsed laser-induced breakdowns of fused silica ($SiO_{2}$) by using the multivariate Fokker-Planck equation. The nonlocal type of multivariate Fokker-Planck equation is modeled on the basis of the Boltzmann transport formalism to describe the ultra-short pulsed laser-induced damage phenomena in the energy-position space, together with avalanche ionization, three-body recombination, and multiphoton ionization. Effects of electron avalanche, recombination, and multiphoton ionization on the electronic transport are examined. From the results, it is observed that the recombination becomes prominent and contributes to reduce substantially the rate of increase in electron number density when the electron density exceeds a certain threshold. With very intense laser irradiation, a strong absorption of laser energy takes place and an initially transparent solid is converted to a metallic state, well known as laser-induced breakdown. It is also found that full ionization is provided at intensities above threshold, all further laser energy is deposited within a thin skin depth.

• Journal of Korean Neurosurgical Society
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• v.55 no.1
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• pp.40-42
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• 2014

A correlation between radiation therapy and cavernoma has been suspected since 1994. Since then, only a few cases of radio-induced cavernomas have been reported in the literature (85 patients). Most of them were children, and the most frequent original tumour had been medulloblastoma. The authors report a case of two cystic cavernous angiomas after radiation therapy for atypical meningioma in adult woman. This is the first case of cavernous angioma after radiotherapy for low grade meningioma. A 39-year-old, Latin american woman was operated on for a frontal atypical meningioma with intradiploic component and adjuvant radiotherapy was delivered (6000 cGy local brain irradiation, fractionated over 6 weeks). Follow-up MR imaging showed no recurrences of the tumour and no other lesions. Ten years later, at the age of 49, she consulted for progressive drug-resistant headache. MR imaging revealed two new well defined areas of different signal intensity at the surface of each frontal pole. Both lesions were surgically removed; the histopathological diagnosis was cavernous angioma. This is the first case of cavernous angioma after radiation therapy for atypical meningioma : it confirms the development of these lesions after standard radiation therapy also in patients previously affected by non-malignant tumours.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1096-1099
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• 2001

The basic design structure of RC-GCTs (Reserve-Conducting Gate-Commutated Thyristors) is firstly given in this paper. The bulk of wafer is punch-through (PT) type with high resistivity and narrow N-base width. The photo-mask was designed upon the turn-off characteristics of GCT and solution of separation between GCT and diode part. The center part of Si wafer is free-wheeling diode (FWD) and outer is GCT part which has 240 fingers totally. The switching performance of GCT was investigated by Dessis of ISE. The basic manufacture process of 2500V-4500V RC-GCTs was given in this work. Additionally, the local carrier lifetime control by 5Mev proton irradiation was adopted so as to not only to have the softness of reverse recovering for FWD but for reduction of turn-off losses of GCT as well.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1109-1114
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• 2009

The evolution of a high burnup structure (HBS) in a light water reactor (LWR) $UO_2$ fuel was simulated using the Potts model. A simulation system for the Potts model was defined as a two-dimensional triangular lattice, for which the stored energy was calculated from both the irradiation damage of the $UO_2$ matrix and the formation of a grain boundary in the newly recrystallized small HBS grains. In the simulation, the evolution probability of the HBS is calculated by the system energy difference between before and after the Monte Carlo simulation step. The simulated local threshold burnup for the HBS formation was 62 MWd/kgU, consistent with the observed threshold burnup range of 60-80 MWd/kgU. The simulation revealed that the HBS was heterogeneously nucleated on the intergranular bubbles in the proximity of the threshold burnup and then additionally on the intragranular bubbles for a burnup above 86 MWd/kgU. In addition, the simulation carried out under a condition of no bubbles indicated that the bubbles played an important role in lowering the threshold burnup for the HBS formation, thereby enabling the HBS to be observed in the burnup range of conventional high burnup fuels.