• Carbon letters
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• v.2 no.3_4
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• pp.192-201
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• 2001

The Carbon/Carbon composite was prepared from 3D carbon fiber preform and coal tar pitch as matrix precursor. In order to evaluate of ablative characteristics of the composite, liquid rocket system was employed Kerosene and liquid oxygen was used as propellants, operating at a nominal chamber pressure of 330 psi and a nominal mixture ratio (O/F) of 2.0. The results of an experimental evaluation were that high density composite exhibited high, while low density composites showed low erosion resistance. The erosion rate against heat flux was highly depended on the density of the materials. The morphology of eroded fiber showed differently according to collision angle with heat flux on the composite. The granular matrix which derived from carbonization pressure of 900 bar was more resistance to heat flux than well-developed flow type matrix.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.200.2-200.2
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• 2016

Carbon-based materials have been known as ablative material and have been used for thermal protection systems. Ablation is an erosive phenomenon that results in thermochemical and thermomechanical changes on materials. Ablation resistance is one of the key properties that determines performance and life-time of the thermal protection material under ablative conditions. In this study, ablation properties of graphite, 3-dimensional (C/C) composites (needle-punched type and rod type) were investigated byusing a plasma wind tunnel which produce a supersonic plasma flow from a segmented arc heater with the power level of 0.4 MW. The mass losses and surface roughness changes which contain main result of the ablation are measured. A morphological analysis ofthe carbon-based materials, before and after the ablation test, are performed through field emission scanning electron microscopy (FE-SEM) and non-contact 3D surface measuring system. Electronic balance and a portable surface roughness tester were used for evaluation of the recession and mass loss of the test samples.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.335-340
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• 2005

A study on the variation of combustion characteristics by injector geometries was conducted. Coaxial swirl injectors were used. Existence of swirl chamber and variation of a nozzle length become key parameters. Injectors were identified as open, closed and mixed type by existence of swirl chamber. Variation of nozzle length was made extruding the both nozzle along the axis while other design parameters remain the same. A uni-element combustor with ablative material liner and a water cooled nozzle made by oxygen free copper with outer stainless steel casing were used.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.5
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• pp.265-270
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• 2016

Objectives: To gain information on anatomical variation in anterolateral thigh (ALT) flaps in a series of clinical cases, with special focus on perforators and pedicles, for potential use in reconstruction of oral and maxillofacial soft tissue defects. Materials and Methods: Eight patients who underwent microvascular reconstructive surgery with ALT free flaps after ablative surgery for oral cancer were included. The number of perforators included in cutaneous flaps, location of perforators (septocutaneous or musculocutaneous), and the course of vascular pedicles were intraoperatively investigated. Results: Four cases with a single perforator and four cases with multiple perforators were included in the ALT flap designed along the line from anterior superior iliac spine to patella. Three cases had perforators running the septum between the vastus lateralis and rectus femoris muscle (septocutaneous type), and five cases had perforators running in the vastus lateralis muscle (musculocutaneous type). Regarding the course of vascular pedicles, five cases were derived from the descending branch of the lateral circumflex femoral artery (type I), and three cases were from the transverse branch (type II). Conclusion: Anatomical variation affecting the distribution of perforators and the course of pedicles might prevent use of an ALT free flap in various reconstruction cases. However, these issues can be overcome with an understanding of anatomical variation and meticulous surgical dissection. ALT free flaps are considered reliable options for reconstruction of soft tissue defects of the oral and maxillofacial area.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.3697-3703
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• 2016

Hepatocellular carcinoma (HCC) is the most frequent type of malignant liver tumor and a high impact health problem worldwide. The prevalence of HCC is particularly high in many Asian and African countries. Some HCC patients have no symptoms prior to diagnosis and many of them therefore present at late stage and have a grave prognosis. The well-established causes of HCC are chronic hepatitis B virus (HBV) or chronic hepatitis C virus (HCV) infection or alcoholic cirrhosis and nonalcoholic steatohepatitis. The Barcelona Clinic Liver Cancer (BCLC) Staging System remains the most widely used for HCC management guidelines. To date, the treatments for HCC are still very challenging for physicians due to limited resources in many parts of the world, but many options of management have been proposed, including hepatic resection, liver transplantation, ablative therapy, chemoembolization, sorafnib and best supportive care. This review article describes the current evidence-based management of HCC with focus on early to advance stages that impact on patient overall survival.

• Journal of the Korean Wood Science and Technology
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• v.34 no.6
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• pp.36-43
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• 2006

Using fluidized bed type fast pyrolysis system (capacity 400 g/h) bio-oils were produced from beech (Fagus sylvatica) and softwood mixture (spruce and larch, 50:50). The pyrolysis was performed for 1~2 s at the temperature of $470{\pm}5^{\circ}C$. Pyrolysis products consisted of liquid form of bio-oil, char and gases. In beech wood bio-oil was formed to ca. 60% based on dry biomass weight and the yield of bio-oil was 49% in soft wood mixture. The moisture contents in both bio-oils were ranged between 17% and 22% and the bio-oil's density was measured to $1.2kg/{\ell}$. Bio-oils were composed of 45% carbon, 47% oxygen, 7% hydrogen and lower than 1% nitrogen,which was very similar to those of original biomass. In comparison with oils from fossil resources, oxygen content was very high in bio-oils, while no sulfur was found. More than 90 low molecular weight components, classified to aromatic and non aromatic compounds, were identified in bio-oils by gas chromatographic analysis, which amounted to 31~33% based on the dry weight of bio-oils.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.5
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• pp.406-414
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• 2001

In recent decade, there has been a very rapid development in technical possibilities to provide patients with maxillofacial prostheses. Dr. Brenemark first introduced possibility of use of maxillofacial interosseous implant in patients with ablative tumor surgery in 1979. He did introduce the new type of maxillofacial implants system which widen the fixture flange on top of the bone. The advantages of fixed prostheses with implants were well known to various ways, easy to attach, keep clean prostheses, and not to disturb recipient bed. But there are some problems to install implants on maxillofacial regions, because mostly facial bone has very thin cortical bone and poor bone quality. It needs more retention between implant and bone which overcome that fault with fixture flange. To make maxillofacial prostheses, it should be understood general procedure of maxillofacial laboratory work. Ear and midface maxillofacial fabrication which include nose and eye defects will be described step by step.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.1
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• pp.127-130
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• 2012

Aim: We conducted a study in China to assess the health-related quality of life (HRQoL) in patients treated on for malignant bone tumors after surgery, and investigate the possible determinants. Methods: The subjects were 120 patients surgically treated by amputation and limb-salvage for bone tumors during the period of June 2008 to June 2010. The Medical Outcomes Study Short Form 36 (SF-36) was employed to measure the HRQoL of all the patients before and after surgery. Results: With regard to the results of the general quality of life tool (SF-36), we observed a significant improvement of all the indexes of HRQoL after 6 months (p<0.05). PF, RP and BP scores showed significant increase between surgery after 6 and 12 months (p<0.05). The means of the HRQoL of bone tumor patients in our study were still much lower than those of general population in every domain, even 12 months after surgery. Logistic regression showed that female patients were found to have lower scores in physical component summary (PCS) than males (OR=0.64, 95% CI=0.35-0.89). Patients older than 15 years had lower scores in mental component summary (MCS) (OR=0.60, 95% CI=0.32-0.86). Ablative surgery was related to both lower MCS and PCS scores (For MCS, OR=0.54, 95% CI=0.31-0.83; for PCS, OR=0.43, 95% CI=0.25-0.73). Conclusion: Our study showed the treatment for bone tumor could greatly alter the HRQoL of patients. Age, sex and type of surgery were associated with physical or mental HRQoL after surgery.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.80-87
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• 2004

To understand the each performance parameter correlation of flight type liquid-propellant rocket engine for KSR-III(Korea Sounding Rocket-III), the analysis of engine stand-alone combustion test results was carried out. Considering the variation of ablative material combustion chamber caused by erosion, linear regression analysis that ignores oxidizer/fuel ratio effect and two-variable 2nd-order polynomial regression analysis that considers oxidizer/fuel ratio change were performed. It can be described that linear regression analysis is simple and very practical method, and can predict the performance within 1% error inside analyzed region. And two-variable 2nd-order polynomial regression analysis can predict with very high accuracy inside region and shows that KSR-III engine's optimum oxidizer/fuel ratio for thrust(or specific impulse) is 2.22 and that for combustion chamber pressure(or characteristic velocity) is 2.17.

• Archives of Reconstructive Microsurgery
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• v.9 no.1
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• pp.6-14
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• 2000

Reconstruction of the composite mandibular defect resulting from ablative resection of tumor involved jaw has been challenging task to the plastic surgeon. A wide variety of different techniques were used with limited success until the advent of microsurgery. The high success rate of microsurgical procedures has allowed for significant improvement in both functional and aesthetic results. A variety of free flap donor sites have been used successfully for mandibular reconstruction. Between April of 1991 and August of 1998, 20 mandibular reconstructions were performed for oncologic defects. 4 patients underwent mandibular reconstruction with pectoralis major flap, 3 patients with free nonvascularized bone graft, 1 patient with metal plate. 12 patients underwent microvascular mandibular reconstruction(8: fibula, 4: ilium). The type of free flap was determined by the requirements of the defect. Satisfactory aesthetic and functional results were achieved in all cases without significant complications. So microvascular mandibular reconstruction should be considered as primary choice in all mandibular defect without hesitation.