• 한국연소학회:학술대회논문집
• /
• 2005.10a
• /
• pp.328-336
• /
• 2005

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine the chemical quenching phenomenon, we prepared thermally grown silicon oxide plates with well-defined defect density. Ion implantation was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove the oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}C$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The analysis shows that as the ion energy increases, the number of structural defect also increases and non-stoichiometric condition of $SiO_x(x{\le}2)$ plates is enhanced. From the quenching distance measurements, we found out that when the surface temperature is under $300^{\circ}C$, the quenching distance decreases on account of reduced heat loss; as the surface temperature increases over $300^{\circ}C$, however, quenching distance increases despite reduced heat loss effect. Such aberrant behavior is caused by heterogeneous chemical reaction between active radicals and surface defect sites. The higher defect density, the larger quenching distance. This results means that chemical quenching is governed by radical adsorption and can be parameterized by the oxygen vacancy density on the surface.

• Archives of Reconstructive Microsurgery
• /
• v.20 no.1
• /
• pp.8-13
• /
• 2011

Purpose: A palatal defect following maxillectomy can cause multiple problems like the rhinolalia, leakage of foods into the nasal cavity, and hypernasality. Use of a prosthetic is the preferred method for obturating a palate defect, but for rehabilitating palatal function, prosthetics have many shortcomings. In a small defect, local flap is a useful method, however, the size of flap which can be elevated is limited. In 12 cases of palatomaxillary defect, we used various microvascular free flaps in reconstructing the palate and obtained good functional results. Method: Between 1990 and 2004, 12 patients underwent free flap operation after head and neck cancer ablation, and were reviewed retrospectively. Among the 12 free flaps, 6 were latissimus dorsi myocutaneous flaps, 3 rectus abdominis myocutaneous flaps, and 3 radial forearm flaps. Result: All microvascular flap surgery was successful. Mean follow up time was 8 months and after the follow up time all patients reported satisfactory speech and swallowing. Wound dehiscence was observed in 4 cases, ptosis was in 1 case and fistula was in 1 case, however, rhinolalia, leakage of food, or swallowing difficultly was not reported in the 12 cases. Conclusion: We used various microvascular flaps for palatomaxillary reconstruction. For 3-dimensional flap needs, we used the latissimus dorsi myocutaneous flap to obtain enough volume for filling the defect. Two-dimensional flaps were designed with latissimus dorsi myocutaneous flap, rectus abdominis flap and radial forearm flap. For cases with palatal defect only, we used the radial forearm flap. In palatomaxillary reconstruction, we can choose various free flap techniques according to the number of skin paddles and flap volume needed.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.40
• /
• pp.11.1-11.5
• /
• 2018

Background: Squamous cell carcinoma (SCC) is the most commonly occurring malignant tumor in the oral cavity. In South Korea, it occurs most frequently in the mandible, tongue, maxilla, buccal mucosa, other areas of the oral cavity, and lips. Radial forearm free flap (RFFF) is the most widely used reconstruction method for the buccal mucosal defect. The scar of the forearm donor, however, is highly visible and unsightly, and a secondary surgical site is needed when such technique is applied. For these reasons, buccal fat pad (BFP) flap has been commonly used for closing post-surgical excision sites since the recent decades because of its reliability, ease of harvest, and low complication rate. Case presentation: In the case reported herein, BFP flap was used to reconstruct a cheek mucosal defect after excision. The defect was completely covered by the BFP flap, without any complications. Conclusion: Discussed herein is the usefulness of BFP flap for the repair of the cheek mucosal defect. Also, further studies are needed to determine the possibility of using BFP flap when the defect is deep, and the maximum volume that can be harvested considering the changes in volume with age.

• Archives of Reconstructive Microsurgery
• /
• v.17 no.1
• /
• pp.14-18
• /
• 2008

Purpose: Evaluation of results of free flap as a method of reconstruction in soft tissue defect after wide excision of soft tissue tumor of extremity. Materials and Methods: From 2000 through 2007, 11 patients received free flap surgery for soft tissue defect after wide excision operation for soft tissue tumor of limbs. Four cases were upper extremities and seven were lower extremities. Four subjects were diagnosed as squamous cell carcinoma, three as malignant melanoma, two as synovial sarcoma and one as malignant fibrous histiocytoma and alveolar soft part sarcoma. Donor sites of free flap varied with anterolateral thigh flaps in six cases, latissimus dorsi flaps in four, reverse forearm flap in one. By the method of doppler ultrasound, venous circulation was evaluated for the survival of each flap on the third, fifth and seventh day respectively after the operation. Results: 10 of 11 free flaps were successfully survived. Necrosis of free flaps in 1 cases occurred in case of anterolateral thigh flap. Conclusion: Free flap can be a useful method for reconstruction of soft tissue defect after wide excision of soft tissue sarcoma of extremity.

• Analytical Science and Technology
• /
• v.10 no.1
• /
• pp.18-30
• /
• 1997

Na, TPA-ZSM-5 with Si / Al mole ratio of about 130 was synthesized at low temperature and atmospheric pressure. These intermediate products were characterized by using XRD, XRF, FT-IR, NMR, and SEM. As a result, intermediate product were different from those that synthesized by autoclave method but spectroscopic characteristics of the final products showed to be in the typical ZSM-5 region. The defect sites were observed in the final product and removed by calcination at $540^{\circ}C$. Na, TPA-ZSM-5, aboveall, was synthesized at this condition within 48hr.

• Journal of Periodontal and Implant Science
• /
• v.37 no.2
• /
• pp.181-192
• /
• 2007

Periodontal surgery as part of the treatment of periodontal disease is mainly performed 1) to gain access to diseased areas for adequate cleaning; 2) to achieve pocket reduction or elimination; and 3) to restore the periodontal tissues lost through the disease; i.e., a new attachment formation of periodontal regeneration. To accomplish the latter, often referred to as the ultimate goal of periodontal therapy, a number of surgical procedures have been advocated throughout the years. Clinical studies have demonstrated that considerable gain of clinical attachment and bone can be achieved following guided tissue regeneration (GTR) therapy of intrabony defects. The aim of this study was to analyse the radiographic bone changes 2-year after GTR using a bone graft material and nonresorbable membrane. Patients attending the department of periodontics of Kyungpook National University Hospital were studied. Patients had clinical and radiographic evidence of intrabony defect(s), 33 sites of 30 patients aged 32 to 56 (mean age 45.6) were treated by GTR with a bone graft material and nonresorbable membrane. Baseline and 2-year follow-up radiographs were collected and evaluated for this study. Radiographic assessment includes a bone fill, bone crest change, defect resolution, and % of defect resolution. Pre- and post-treatment differences between variables (maxilla and mandible, defect depth, defect angle, bone graft materials) using the paired t-test were examined. We observed $2.86{\pm}1,87mm$ of bone fill, $065{\pm}0.79mm$ of crestal resorption, $3.49{\pm}2.11mm$ of defect resolution, and $44.42{\pm}19.51%$ of percentage of defect resolution. Mandible, deeper initial defect depth, narrower initial defect angle showed greater bone fill, defect resolution, and % of defect resolution. But no difference was observed between xenograft and allograft. Outcome of GTR as a therapy of intrabony defect was better than other therapy, but herein, good oral hygiene maintenance as a anti-infective treatment and periodic recall check of patients are essential.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.38
• /
• pp.46.1-46.7
• /
• 2016

Background: Osteoradionecrosis is the most dreadful complication after head and neck irradiation. Orocutaneous fistula makes patients difficult to eat food. Fibular free flap is the choice of the flap for mandibular reconstruction. Osteocutaneous flap can reconstruct both hard and soft tissues simultaneously. This study was to investigate the success rate and results of the free fibular flap for osteoradionecrosis of the mandible and which side of the flap should be harvested for better reconstruction. Methods: A total of eight consecutive patients who underwent fibula reconstruction due to jaw necrosis from March 2008 to December 2015 were included in this study. Patients were classified according to stages, primary sites, radiation dose, survival, and quality of life. Results: Five male and three female patients underwent operation. The mean age of the patients was 60.1 years old. Two male patients died of recurred disease of oral squamous cell carcinoma. The mean dose of radiation was 70.5 Gy. All fibular free flaps were survived. Five patients could eat normal diet after operation; however, three patients could eat only soft diet due to loss of teeth. Five patients reported no change of speech after operation, two reported worse speech ability, and one patient reported improved speech after operation. The ipsilateral side of the fibular flap was used when intraoral soft tissue defect with proximal side of the vascular pedicle is required. The contralateral side of the fibular flap was used when extraoral skin defect with proximal side of the vascular pedicle is required. Conclusions: Osteonecrosis of the jaw is hard to treat because of poor healing process and lack of vascularity. Free fibular flap is the choice of the surgery for jaw bone reconstruction and soft tissue fistula repair. The design and selection of the right or left fibular is dependent on the available vascular pedicle and soft tissue defect sites.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.81-81
• /
• 2008

Applications of CdS films in this study are to exhibit a high conductivity when they are exposed at light with visible wavelength and sequentially to show a low conductivity in dark state. For this purpose, CdS films should have a high photosensitivity, still maintaining a high conductivity at a visible light. In this study, CdS films were prepared at room temperature on glass substrates by rf magnetron sputtering. In order to increase the photo-conductivity in visible light, various defect levels should be located within the CdS band gap. In order to nucleate the defect sites within the CdS band gap, CdS films were deposited on glass substrates at room temperature using various $H_2$/(Ar+$H_2$) flow ratios by an rf magnetron sputtering. Through the investigation of the structural and photoconductive properties of CdS films by an addition of hydrogen, the relationship between photo- and dark-resistance in CdS films was investigated in detail. 200-nm-thick CdS films for photoconductive sensor applications were prepared at various $H_2$/(Ar+$H_2$) flow ratios on glass substrates at room temperature by rf magnetron sputtering. Sulfur concentration in CdS films crystallized at room temperature with (002) preferred orientation depends directly on the hydrogen atmosphere and the surface roughness of the films gradually increases with increasing hydrogen atmosphere. Films deposited at 8% of $H_2$/(Ar+$H_2$) exhibit an abrupt decrease of dark- and photo-resistance, showing a low photo-sensitivity ($R_{dark}/R_{photo}$). Onthe other hand, films deposited at a hydrogen atmosphere of 42% exhibit a photo-sensitivity of $5\times10^3$, maintaining a photo-resistance of an approximately $2\times10^4\Omega$/square. The dark- and photo-resistance values of CdS films were related with a composition, surface roughness, and defect sites within the band gap.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.28 no.6
• /
• pp.586-589
• /
• 2006

Deep circumflex iliac artery (DCIA) flap can be harvested as a composite free flap and is often used to adequately reconstruct wide mandibular defects. However, the harvesting of this DCIA flap can result in severe osseous defect of the donor site causing a morphologic defect in the iliac crest. To reconstruct this defect of the iliac donor site, several innovative techniques using bioactive ceramic spacers, autogenous rib bone, polylactic acid mesh, or titanium plates have been introduced. Nonetheless, these methods have not been widely used due to high cost, secondary donor site morbidity, difficulty of use, and postoperative dissatisfaction. We used two titanium plates to reconstruct the donor iliac site defect at the harvesting time of primary DCIA flap surgery in the 30-year old female with an ameloblastoma in the left mandible. Postoperatively, both iliac sites were relatively balanced and there were few complications. At the 2 years follow-up, there were no specific abnormal radiographic findings and the patient was very satisfied with her esthetic iliac contouring. In our report, we evaluate the effect of two titanium plates on the reconstruction of the iliac donor site in the aspects of esthetics and usefulness. This technique has many advantages, such as reduced cost, simplicity, decreased postoperative pain or discomfort, and improved bilateral balance of both anterior iliac crest contours, especially in young female patients.

• Journal of Periodontal and Implant Science
• /
• v.45 no.6
• /
• pp.229-237
• /
• 2015

Purpose: The aim of this study was to determine the clinical feasibility of using dehydrothermally cross-linked collagen membrane (DCM) for bone regeneration around peri-implant dehiscence defects, and compare it with non-cross-linked native collagen membrane (NCM). Methods: Dehiscence defects were investigated in twenty-eight patients. Defect width and height were measured by periodontal probe immediately following implant placement (baseline) and 16 weeks afterward. Membrane manipulation and maintenance were clinically assessed by means of the visual analogue scale score at baseline. Changes in horizontal thickness at 1 mm, 2 mm, and 3 mm below the top of the implant platform and the average bone density were assessed by cone-beam computed tomography at 16 weeks. Degradation of membrane was histologically observed in the soft tissue around the implant prior to re-entry surgery. Results: Five defect sites (two sites in the NCM group and three sites in the DCM group) showed soft-tissue dehiscence defects and membrane exposure during the early healing period, but there were no symptoms or signs of severe complications during the experimental postoperative period. Significant clinical and radiological improvements were found in all parameters with both types of collagen membrane. Partially resorbed membrane leaflets were only observed histologically in the DCM group. Conclusions: These findings suggest that, compared with NCM, DCM has a similar clinical expediency and possesses more stable maintenance properties. Therefore, it could be used effectively in guided bone regeneration around dehiscence-type defects.