• Journal of Korean Neurosurgical Society
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• v.53 no.5
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• pp.281-287
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• 2013

Objective : Pleomorphic xanthoastrocytoma (PXA) is a rare primary low-grade astrocytic tumor classified as WHO II. It is generally benign, but disease progression and malignant transformation have been reported. Prognostic factors for PXA and optimal therapies are not well known. Methods : The study period was January 2000 to March 2012. Data on MR findings, histology, surgical extents and adjuvant therapies were reviewed in twenty-two patients diagnosed with PXA. Results : The frequent symptoms of PXA included seizures, headaches and neurologic deficits. Tumors were most common in the temporal lobe followed by frontal, parietal and occipital lobes. One patient who died from immediate post-operative complications was excluded from the statistical analysis. Of the remaining 21 patients, 3 (14%) died and 7 (33%) showed disease progression. Atypical tumor location (p<0.001), peritumoral edema (p=0.022) and large tumor size (p=0.048) were correlated with disease progression, however, Ki-67 index and necrosis were not statistically significant. Disease progression occurred in three (21%) of 14 patients who underwent GTR, compared with 4 (57%) of 7 patients who did not undergo GTR, however, it was not statistically significant. Ten patients received adjuvant radiotherapy and the tumors were controlled in 5 of these patients. Conclusion : The prognosis for PXA is good; in our patients overall survival was 84%, and event-free survival was 59% at 3 years. Atypical tumor location, peritumoral edema and large tumor size are significantly correlated with disease progression. GTR may provide prolonged disease control, and adjuvant radiotherapy may be beneficial, but further study is needed.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.263-273
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• 1998

For histologic observation of the regenerated bone following guided tissue regeneration (GTR) using ePTFE membranes with calcium carbonate implant and autogenous bone graft, biopsies were collected from 2 patients during 5-year-postoperative surgical reentry. In both combined cases with guided tissue regeneration in conjunction with calcium carbonate implant and autogenous bone graft, significant bone fill and gain in probing attachment level was observed. In histologic examination, specimen in GTR case with calcium carbonate grafting was composed of a dense bone containing vascular channel with lamellar structure and viable bone cells in lacunae, however considerable calcium carbonate particles remained unresorbed and isolated from regenerated bone by the dense cellular and fibrous connective tissue. No formative cells could be seen in contact with remained calcium carbonate particles. In GTR case with autogenous bone grafting, specimen show was composed of a dense lamellar bone containing vascular channel, which showed normal alveolar bone architectures. The present observation indicate that guided tissue regeneration in conjunction with grafting, especially autogenous bone graft, has highly osteogenic potential, however resorbable calcium carbonate granules were not completely resorbed at 5 year postimplantation.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.509-522
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• 2004

This study was performed to compare the clinical effectiveness of two regenerative techniques for class II furcation involvements in human: a combination of bone grafts with PRP vs. GTR with bone grafts. The e-PTFE group was treated with non-absorbable membrane and bone grafts, the PRP group was treated with PRP and bone grafts Pocket depth, clinical attachment level, and gingival recession were measured at baseline and postoperative 6 months. Vertical and horizontal furcation depth were measured by re-entry surgeries at 6 months post-treatment Both groups were statistically analyzed by Wilcoxon signed Ranks Test & Mann-whitney Test using SPSS program (5% significance level). The results were as follows: 1. The change of pocket depth, clinical attachment level, vertical furcation depth and horizontal furcation depth in both groups was decreased significantly at 6 months than at baseline. (p<0.05) 2. The change of gingival recession in both groups was increased significantly at 6 months than at baseline. (p<0.05) 3. The change of alveolar crest absorption in both groups was increased at 6 months than at baseline but there were no statistically significant differences. 4. The change of pocket depth, clinical attachment level, vertical furcation depth and horizontal furcation depth in both groups was increased significantly at 6 months, but there were no statistically or clinically significant differences with both groups. 5. The change of gingival recession and alveolar crest absorption in both groups was increased at 6 months, but there were no statistically or clinically significant differences with both groups. In conclusion, the use of bone graft with PRP or GTR technique improved clinical index of the soft and hard tissue in mandibular class II furcation involvement but there were no statistically or clinically significant differences between bone graft with PRP and GTR technique.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.110-119
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• 1999

The principle of guided tissue regeneration (GTR), as applied to bone healing, is based on the prevention of connective tissue from entering the bony defect during the healing phase. This allows the slower bone producing cells to migrate into and reproduce bone within the defect. The principle of guided tissue regeneration has demonstrated a level of success in regenerating bone defect. Several types of membrane barrier, each one with distinct properties, have been utilized to apply this principle in bone regeneration. The purpose of this study is to introduce and discuss the attributes of rubber dam as a barrier membrane and evaluate whether improved bone regeneration can be achieved by GTR using rubber dam. In the 15 New Zealand white rabbits, full-thickness bone defects on three sites of each rabbit calvaria were made. Non membrane group served as a control and experimental group 1 was covered with rubber dam and group 2 covered with Gore-Tex$^{TM}$ membrane. Macroscopic, radiographic, microscopic examinations were made serially on 1, 2, 3, 6, 12 weeks after operation. The results were as follows: 1. Macroscopically, the control site was collapsed and filled with connective tissue throughout the experimental period. But the defects of experimental groups 1 and 2 were filled with bone-like mass and showed the hard consistency on palpation. 2. Radiographically, the early new bone formation appeared similarly from the host bone in groups 1 and 2. 3. Microscopically, there were much connective tissue at the central part of control site but the defect of group 1 and 2 was filled with the mature bony trabeculae on the 12th week. This results suggest that rubber dam can be effectively used as a barrier membrane for guided bone regeneration.

• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.35.1-35.9
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• 2022

Although the success rates of microsurgery and micro-resurgery are very high, the influence of a recurrent perforation combined with radicular cyst remains unclear. A 21-year-old white female patient had a history of root perforation in a previously treated right maxillary lateral incisor. Analysis using cone-beam computed tomography (CBCT) revealed an extensive and well-defined periapical radiolucency, involving the buccal and palatal bone plate. The perforation was sealed with bioceramic material (Biodentine) in the pre-surgical phase. In the surgical phase, guided tissue regeneration (GTR) was performed by combining xenograft (lyophilized bovine bone) and autologous platelet-rich fibrin applied to the bone defect. The root-end preparation was done using an ultrasonic tip. The retrograde filling was performed using a bioceramic material (Biodentine). Histopathological analysis confirmed a radicular cyst. The patient returned to her referring practitioner to continue the restorative procedures. CBCT analysis after 1-year recall revealed another perforation in the same place as the first intervention, ultimately treated by micro-resurgery using the same protocol with GTR, and a bioceramic material (MTA Angelus). The 2-year recall showed healing and bone neoformation. In conclusion, endodontic micro-resurgery with GTR showed long-term favorable results when a radicular cyst and a recurrent perforation compromised the success.

• Brain Tumor Research and Treatment
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• v.6 no.2
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• pp.60-67
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• 2018

Background Recently, modern technology such as diffusion tensor imaging (DTI), neuro-navigation and intraoperative neurophysiological monitoring (IOM) have been actively adopted for the treatment of thalamic tumors. We evaluated surgical outcomes and efficacy of the aforementioned technologies for the treatment of pediatric thalamic tumors. Methods We retrospectively reviewed clinical data from 37 children with thalamic tumors between 2004 and 2017. There were 44 operations (27 tumor resections, 17 biopsies). DTI was employed in 17 cases, neuro-navigation in 23 cases and IOM in 14 cases. All diagnoses were revised according to the 2016 World Health Organization Classification of Tumors of the Central Nervous System. Progression-free survival (PFS) and overall survival (OS) rates were calculated, and relevant prognostic factors were analyzed. The median follow-up duration was 19 months. Results Fifteen cases were gross total resections (GTR), 6 subtotal resections (STR), and 6 partial resections (PR). Neurological status did not worsen after 22 tumor resections. There were statistically significant differences in terms of the extent of resection between the groups with DTI, neuro-navigation and IOM (n=12, GTR or STR=12) and the group without at least one of the three techniques (n= 15, GTR or STR=9, p=0.020). The mean PFS was $87.2{\pm}38.0$ months, and the mean OS $90.7{\pm}36.1$ months. The 5-year PFS was 37%, and the 5-year OS 47%. The histological grade ($p{\leq}0.001$) and adjuvant therapy (done vs. not done, p=0.016) were significantly related to longer PFS. The histological grade (p=0.002) and the extent of removal (GTR/STR vs. PR/biopsy, p=0.047) were significantly related to longer OS. Conclusion Maximal surgical resection was achieved with acceptable morbidity in children with thalamic tumors by employing DTI, neuro-navigation and IOM. Maximal tumor resection was a relevant clinical factor affecting OS; therefore, it should be considered the initial therapeutic option for pediatric thalamic tumors.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.5
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• pp.500-508
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• 2014

In the ongoing debates over the need to identify new sources of energy and to reduce the emissions of greenhouse gases. Hydrogen has emerged as one of the most promising alternatives due to its emissions from the vehicle being virtually zero. The governments have identified the development of regulations and standards as one of the key requirements for commercialization of HFCV. Regulations and standards will help overcome technological barriers to commercialization. The development of Global Technical Regulation (GTR) for HFCV occurred under the World Forum for Harmonization of Vehicle Regulations. Development of a technique for safety assessment of HFCV include four tasks, research for regulation system and policy, hydrogen safety, vehicle operation safety and protection against high-voltage. The objective is to establish a technique for safety assessment and amend safety standards for HFCV and consequently reflect research results to vehicle management policy. We devised safety standards and evaluation techniques with regard to high-pressure gas and high voltage of hydrogen fuel cell vehicle. KMVSS for HFCV was amended to June 10, 2014. including the results of the safety assessment technology for high-voltage and hydrogen characteristics.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.4
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• pp.520-526
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• 2011

In recent years, it is very important that hydrogen storage system is safe for user in any circumstances in case of crash and fire. Because the hydrogen vehicle usually carry high pressurized cylinders, it is necessary to do safety design for fire. The Global Technical Regulation (GTR) has been enacted for localized and engulfing fire test. High pressure hydrogen storage system of fuel cell electrical vehicles are equipped with Thermal Pressure Relief Device (TPRD) installed in pressured tank cylinder to prevent the explosion of the tank during a fire. TPRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. In this paper, we observed the localized and engulfing behavior of tank safety, regarding the difference of size and types of the tanks in accordance with GTR.

• Journal of Auto-vehicle Safety Association
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• v.13 no.1
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• pp.51-56
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• 2021

As hydrogen is classified as an eco-friendly fuel, vehicles using hydrogen fuel are being developed worldwide. Vehicle fuel hydrogen is stored in cylinders at 70 MPa, so there is a high risk of explosion. Therefore, it is important to inspect hydrogen cylinders in used-vehicles. This study was conducted to improve the inspection method of the cylinders currently mounted on used-hydrogen buses. The inspection method is an image analysis method using a camera. Calcaulation algorithm was developed to quantitatively chech the amount of hydrogen leakage by the image method. As a result of adding a contact angle element to the calculation algorithm suggested by the GTR regulation and comparing it with the experimental data of the GTR regulation, the algorithm reliability was 94%, which secured similarity.

• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.472-478
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• 2001

Objectives : The authors present a retrospective analysis of 100 consecutive adult patients harboring craniopharyngiomas who underwent microsurgical resection between 1981 and 1999 to assess the long-term outcome of surgical treatment and to determine the most optimal management strategy. Methods : The extent of surgical removal was divided into four categories ; GTR(gross total removal), RSTR(radical subtotal removal), STR(subtotal removal),and PR(partial removal). The median follow-up period was 50 months(4-198). CT scan and/or MR imaging and hormonal status were evaluated to the last follow-up. Results : Visual disturbance was the most common presentation, which was improved in 42 cases and aggravated in 19 cases following the operation. Hypopituitarism was detected in 56 patients preoperatively, 82 during the immediate postoperative period, and 76 at the last follow-up. Improvement of pituitary function was not observed in any of these patients. Twenty of 100 patients showed recurrence at the mean of 27 months(3 to 196). The median progression-free survival(PFS) time of all patients was 145 months and 5-year PFS rate was 74%. Five-year PFS rate of GTR or RSTR group(71%) was significantly higher than that of STR or PR group(30%)(p=0.01). Postoperative radiation therapy significantly prolonged the PFS from 94 months in non-radiation group to 182 months(p=0.002). However, there was no statistical difference in number of patients who required hormonal replacement therapy between radiation and non-radiation group. Conclusion : Visual disturbance can be improved by early diagnosis and surgical decompression. GTR or RSTR in selected patients is considered a proper surgical strategy. Post-operative radiation therapy for residual tumors must be considered, although the ideal timing of radiation therapy is to be determined.