• Title/Summary/Keyword: Defect

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Development of Digital-Image-Correlation Technique for Detecting Internal Defects in Simulated Specimens of Wind Turbine Blades (풍력 블레이드 모의 시편의 내부 결함 검출을 위한 이미지 상관법 기술 개발)

  • Hong, Kyung Min;Park, Nak Gyu
    • Korean Journal of Optics and Photonics
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    • v.31 no.5
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    • pp.205-212
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    • 2020
  • In the performance of a wind turbine system, the blades play a vital role. However, they are susceptible to damage arising from complex and irregular loading (which may even cause catastrophic collapse), and they are expensive to maintain. Therefore, it is very important both to find defects after blade manufacturing is completed and to find damage after the blade is used for a certain period of time. This study provides a new perspective for the detection of internal defects in glass-fiber- and carbon-fiber-reinforced panels, which are used as the main materials in wind turbine blades. A gap or fracture between fiber-reinforced materials, which may occur during blade manufacturing or operation, is simulated by drilling a hole 5 mm in diameter in the middle layer of the laminated material. Then, a digital-image-correlation (DIC) method is used to detect internal defects in the blade. Tensile load is applied to the fabricated specimen using a tensile tester, and the generated changes are recorded and analyzed with the DIC system. In the glass-fiber-reinforced laminated specimen, internal defects were detected from a strain value of 5% until the end of the experiment, while in the case of the carbon-fiber-reinforced laminated specimen, internal defects were detected from 1% onward. It was proved using the DIC system that the defect was detected as a certain level of strain difference developed around the internal defects, according to the material properties.

A Study on Improvement Options of Objection Procedure in the Supervision and Guidance of Maritime Safety Supervisors (해사안전감독관 지도·감독 이의신청 제도의 개선방안 연구)

  • Lee, Seok-Mal
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.708-716
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    • 2019
  • After the Sewol ferry disaster, the maritime safety supervisor system was introduced to strengthen maritime safety control for coastal vessels. If any critical defect is found in vessel facilities during periodical or occasional guidance and supervision on a vessel, a maritime safety supervisor takes an administrative measure: detention of the vessel until it has been completely corrected. The detention order is one of the most powerful regulations exercised by a maritime safety supervisor. It would not be an overstatement to say that the guidance and supervision conducted by a maritime safety supervisor is very important for the safety of a vessel and protection of the maritime environment. However, the regulatory level of each Regional Office of Oceans and Fisheries toward vessels may vary with the enforcers, and an individual's intentional act or negligence might occur during the execution process. Detention of a coastal vessel by the Regional Office of Ocean and Fisheries can easily lead to delayed navigation, and a vessel owner may suffer economic loss from suspension of a charter party. Nevertheless, the Maritime Safety Act does not prescribe filing a petition for objection to the measure of detention order by a maritime safety supervisor. To overcome this problem, therefore, the objection procedure under the Maritime Safety Act has to be reformed to reclaim a right against an inappropriate detention order measure caused by an individual's intentional act or negligence through a formal objection.

IMPLANT INSTALLATION USING VERTICAL DISTRACTION OSTEOGENESIS AT A SEVERELY ATROPHIED EDENTULOUS MANDIBLE (심하게 위축된 하악골의 완전 무치악 환자에서의 수직 골신장술을 이용한 임플란트 치료)

  • Yeom, Hak-Ryol;Jeon, Seung-Ho;Kim, Yoon-Tae;Paeng, Jun-Young;Ahn, Kang-Min;Myung, Hoon;Hwang, Soon-Jung;Seo, Byoung-Moo;Choi, Jin-Young;Lee, Jong-Ho;Choung, Pill-Hoon;Kim, Myung-Jin
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.28 no.2
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    • pp.154-165
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    • 2006
  • Objectives : It is difficult to place implants at a severely atrophied edentulous mandible because of vertical and horizontal alveolar defect. The autogenous and allogenic bone graft and guided bone regeneration are useful, but there are some limitations such as the resorption and infection of the grafted bone, and insufficiency of soft tissue. Distraction osteogenesis has recently evolved a challenging technique to overcome major draws of conventional augmentation procedures, we, therefore, report the four applications of implant placement after vertical alveolar distraction osteogenesis. Patients and Methods : Four patients(all female, mean age: $60{\pm}6$ years) with severe alveolar ridge deficiencies at their anterior mandible were treated with vertical alveolar distraction osteogenesis by intraoral device(Track 1.5, 15 mm model, KLS Martin, Tuttlingen, Germany) and placement of implants (Branemark MK III, TiUnite). After the latency periods of 5, 7, 8 days, distraction rhythm and rate were $0.5\;mm{\times}2\;times/day$ in the case of good bone quality, and $0.25\;mm{\times}3\;times/day$ in the case of poor bone quality. After consolidation periods of mean fifteen weeks, five implants for each patients were placed at the interforaminal area. Results : On average, a vertical gain of $11.38{\pm}1.38\;mm$ was obtained by distraction. And all distraction zone showed complete ossification by panoramic radiography. There were no postoperative complications other than numbness of lower lip in one case. Total twenty implants in four patients were placed and their outcomes were satisfactory. Conclusion : It is a useful method to place five implants after vertical distraction osteogenesis of the severely atrophied mandible for the implant-supported fixed prosthesis.

The Effect of Bone Marrow-Derived Osteoblasts on Mandibular Deffect in Rabbit (가토골수에서 유래된 골모세포의 하악골 결손부 이식시 골형성에 미치는 효과)

  • Park, Young-Ju;Nam, Jeong-Hun;Kim, Bo-Gyun;Jeon, Min-Su;Chung, Jae-An;Lee, Jung-Won;Ahn, Jang-Hoon;Gang, Tae-In;Park, Mi-Hee;Lim, Sung-Chul
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.32 no.4
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    • pp.306-312
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    • 2010
  • Purpose: The purpose of this experiment was to evaluate the clinical effect of cultured autoglogous osteoblasts as a way to treat the defect of mandible in rabbits. Materials and Methods: Twelve rabbits were used to determine the rate of osteogenesis. The osteoblasts were obtained from the iliac crest of rabbits using aspiration. They were then cultured in Dulbecco's Modified Eagles's Medium (DMEM) with beta-glycerophosophatate, L-ascorbicacid, and dexamethasone to proliferate and differentiate osteoprogenitor cells. The expression of osteogenic markers were detected by reverse transcription-polymerase chain reaction (RT-PCR) and silver nitrate staining techniques. Five, 10-mm holes were placed in each rabbit mandible to simulate defective regions with the use of a low speed trephine bur. In the experimental group, the previously cited defects were grafted with both activated osteoblastic and autogenous bone. The control group, however, was only grafted with autogenous bone. Both groups were then analyzed at 2, 4, and 8-week intervals using bone histomorphometric analysis. Results: According to histomorphologic analysis, the rates of new bone formation at the 2, 4, and 8-week intervals were 36%, 51%, and 23% for the control group, respectively; 52%, 39%, and 28%, for the experimental group, respectively. The experimental group showed higher rates of new bone formation compared to the control group at both the 2-week and 8-week interval. Conclusion: Bone marrow-derived osteoblasts seems to be a promising bone graft material.

IMMEDIATE IMPLANT PLACEMENT AFTER EXTRACTION OF RETAINED DECIDUOUS TEETH AND IMPACTED CANINES: REPORT OF A CASE (상악 전치부 잔존 유치와 매복 견치 발치 후 즉시 임플란트 식립: 증례 보고)

  • Yoo, Ji-Yeon;Kim, Yeo-Gab;Lee, Baek-Soo;Kwon, Yong-Dae;Choi, Byung-Joon;Kim, Young-Ran;Baek, Jin
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.31 no.4
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    • pp.330-333
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    • 2009
  • Alveolar bone resorption after extraction impairs the necessary bone volume and complicates the case for implant surgery and aesthetic implant prosthesis. Immediate implant surgery after extraction decreases the number of surgical procedures and the duration of treatment, while allowing minimum alveolar bone resorption and preserving the residual bone volume. Although immediate implant holds many advantages such as preservation of hard and soft tissue around the extraction socket, greater implant survival rate and higher patient satisfaction, various complications and high failure rate are discouraging factors for the clinicians. In this case report, severe alveolar bone resorption with soft tissue changes were predicted after the extraction of prolonged retained deciduous incisors and impacted maxillary canines and thus decided on immediate implant procedure. Immediate implant surgery after extraction was carried out with minimal bone reduction and tapered wide-neck implant to establish initial stability. Simultaneous bone graft was done by filling the defect area with iliac cancellous bone with additional onlay-type bone graft and absorbable membrane on the labial bone for upper lip support. A stable and esthetic result was obtained with shortened treatment period.

The Effect of $\beta$-Tricalcium Phosphate and Deproteinized Bovine Bone on Bone Formation in the Defects of Rat Calvaria (흰쥐 두개골 결손부에서 베타-트리칼슘 인산염과 탈단백우골의 골형성 효과)

  • Jung, Seung-Gon;Park, Hong-Ju;Ryu, Sun-Youl
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.32 no.4
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    • pp.313-323
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    • 2010
  • Purpose: This study was conducted to evaluate the effect of beta-tricalcium phosphate (Cerasorb$^{(R)}$, Germany) and deproteinized bovine bone (Bio-Oss$^{(R)}$, Switzerland) grafted to the defect of rat calvaria artificially created and the effect of use of absorbable membrane (BioMesh$^{(R)}$, Korea) on new bone formation. Materials and Methods: Transosseous circular calvarial defects with diameters of 5 mm were prepared in the both parietal bone of 30 rats. In the control group I, no specific treatment was done on the defects. In the control group II, the defects were covered with absorbable membrane. In the experimental group I, deproteinized bovine bone was grafted without absorbable membrane; in the experimental group II, deproteinized bovine bone was grafted with absorbable membrane; in the experimental group III, beta-tricalcium phosphate was grafted without absorbable membrane; in the experimental group IV, beta-tricalcium phosphate was grafted with absorbable membrane. The animals were sacrificed after 3 weeks and 6 weeks respectively, and histologic and histomorphometric evaluations were performed. Results: Compare to the control groups, the experimental groups showed more newly formed bone. Between the experimental groups, beta-tricalcium phosphate showed more resorption than deproteinized bovine bone. Stabilization of grafted material and interception of the soft tissue invasion was observed in the specimen treated with membrane. There was no statistical difference between the experimental group I, III and experimental group II, IV classified by graft material, but statistically significant increase in the amount of newly formed bone was observed in the experimental group I, II and II, IV classified by the use of membrane (P<0.05). Conclusion: Both beta-tricalcium phosphate and deproteinized bovine bone showed similar osteoconductibility, but beta-tricalcium phosphate is thought to be closer to ideal synthetic graft material because it showed higher resorption rate in vivo. Increased new bone formation can be expected in bone graft with use of membrane.

Clinical Cases Analysis of Forearm Free Fasciocutaneous Flaps on Oral Cavity Defect Area (구강 결손부에 적용된 요골 유리전완 피부피판 적용례 분석)

  • Kim, Uk-Kyu;Lee, Kwang-Ho;Song, Won-Wook;Hwang, Dae-Seok;Kim, Yong-Deok;Shin, Sang-Hun;Kim, Jong-Ryoul;Chung, In-Kyo
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.32 no.4
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    • pp.324-331
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    • 2010
  • The radial forearm free flap (RFFF) has become a workhorse flap as a means of reconstructing surgical defects in the head and neck region. We have transferred 12 RFFFs with fasciocutaneous type on oral cavity defects in 12 patients after cancer resection and submucous fibrotic lesion ablation from 2005 to 2007 at Department of oral and maxillofacial surgery, Pusan National University Hospital. We reviewed retrospectively patients' charts and followed up the patients. Clinical analysis on the cases with RFFFs focusing on flap morbidity, indications and available vessels was done. The results of study are follows: 1. RFFF could be applied for all kind of defects after resection of tongue, floor of mouth, buccal mucosa, denuded bone of palate, maxilla, and mandible. 2. All free flaps could be used for primary reconstruction. The survival rate of 12 RFFFs was 92%. Partial marginal loss of the flaps was shown as 3 cases among 12 cases. Large size-vessels like superior thyroid artery, facial artery, internal jugular vein were favorable for microvascular anastomosis. 3. Parenteral nutrition instead of nasal L-tube also can be favorable for postoperative a week for better healing of the flap if the patients couldn't be tolerable with nasal tubing. 4. Donor sites with thigh skin graft were repaired with wrist band for 2 weeks. The complications included scarring, abnormal sensation on hand, and reduced grip strength in few patients, but those didn't induce major side effects. 5. Most RFFFs were well healed even if mortality rate of cancer patients was shown as 50% (5/10 persons). The mortality of patients was not correlated with morbidity of the flaps. We could identify the usefulness of RFFF for restoration of oral function, esthetics if the flap design, tissue transfer indications, and well controlled operation are proceeded.

Maxillary reconstruction using tunneling flap technique with 3D custom-made titanium mesh plate and particulate cancellous bone and marrow graft: a case report

  • Takano, Masayuki;Sugahara, Keisuke;Koyachi, Masahide;Odaka, Kento;Matsunaga, Satoru;Homma, Shinya;Abe, Shinichi;Katakura, Akira;Shibahara, Takahiko
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.41
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    • pp.43.1-43.5
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    • 2019
  • Background: Reconstructive surgery is often required for tumors of the oral and maxillofacial region, irrespective of whether they are benign or malignant, the area involved, and the tumor size. Recently, three-dimensional (3D) models are increasingly used in reconstructive surgery. However, these models have rarely been adapted for the fabrication of custom-made reconstruction materials. In this report, we present a case of maxillary reconstruction using a laboratory-engineered, custom-made mesh plate from a 3D model. Case presentation: The patient was a 56-year-old female, who had undergone maxillary resection in 2011 for intraoral squamous cell carcinoma that presented as a swelling of the anterior maxillary gingiva. Five years later, there was no recurrence of the malignant tumor and a maxillary reconstruction was planned. Computed tomography (CT) revealed a large bony defect in the dental-alveolar area of the anterior maxilla. Using the CT data, a 3D model of the maxilla was prepared, and the site of reconstruction determined. A custom-made mesh plate was fabricated using the 3D model (Okada Medical Supply, Tokyo, Japan). We performed the reconstruction using the custom-made titanium mesh plate and the particulate cancellous bone and marrow graft from her iliac bone. We employed the tunneling flap technique without alveolar crest incision, to prevent surgical wound dehiscence, mesh exposure, and alveolar bone loss. Ten months later, three dental implants were inserted in the graft. Before the final crown setting, we performed a gingivoplasty with palate mucosal graft. The patient has expressed total satisfaction with both the functional and esthetic outcomes of the procedure. Conclusion: We have successfully performed a maxillary and dental reconstruction using a custom-made, pre-bent titanium mesh plate.

THE EFFECTS OF IRRADIATION AND HYPERBARIC OXYGEN THERAPY ON MICROVASCULAR ANASTOMOSIS (방사선조사 및 고압산소요법이 미세혈관 문합술에 미치는 영향)

  • Choi, Sung-Weon;Kim, Byung-Yong;Park, Jung-Hyun;Yoon, Jung-Hoon;Yook, Jong-In;Yoo, Jae-Ha;Lee, Eui-Woong;Cha, In-Ho
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.26 no.5
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    • pp.455-461
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    • 2000
  • Malignant tumors of the head and neck frequently require treatment with both radiotherapy and surgery. Reconstruction of the defect in previously irradiated field is a challenge to surgeon, who must produce both a functional and an esthetic result. Hyperbaric oxygen therapy(HBO) has been used in an attempt to reduce the deleterious effects of radiation. But the issue of whether prior irradiation and HBO of the recipient site of a free flap affects the result of reconstruction continues to generate controversy. So, the effects of irradiation and hypergbaric oxygen therapy on microvascular anastomosis was evaluated in an experimental study in femoral vessels of rats. The experimental groups were divided into 3 groups, contorol group, irradiation group, and irradiation and HBO group. Preoperative irradiation was delivered in the left groin field with single dose corresponding 2,000cGy and total 48 hours of HBO was given 100% oxygen at 2.4 atmosphere for 4 weeks. The femoral vessels of 60 rats were anastomosed after irradiation and HBO treatment. Three days, 1 week, 2 weeks and 4 weeks after surgery, the femoral vessels were evaluated for patency and histopathologic changes. There was no notable effect of irradiation on patency of femoral vessels in rats and the radiation effects were obvious on histological examination which showed the sloughing of the endothelial cells, subintimal hyperplasia and fibrosis on the media and adventitia of femoral arteries. The histologic changes of the femoral veins were mild and not typical. But the effects of hyperbaric oxygen therapy after irradiation was seen not marked difference in irradiation group.

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RADIOGRAPHIC INTERPRETATION OF EXPERIMENTALLY PRODUCED BONY DEFECT ACCORDING TO kVp (관전압 변화에 다른 실험적 골결손부의 방사선사진상의 판독)

  • Nam Hye Kyung;Choi Karp Shik;Kim Chin Soo
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.20 no.2
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    • pp.265-276
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    • 1990
  • The purpose of this experiment was to evaluate radiographic interpretation, of various sized 60 periapical and 60 cancellous lesions in 10 mandibular sections of 5 dogs according to kVp (65, 70, 75, 80 and 85 kVp). The results were as follows; The change of kilovoltage within 65kVp-85kVp range did not have influence on the radiographic interpretation of the same-sized bony defects at the constant radiographic density (p> 0.05). When the bony defects were less than the size of No.2 round bur, radiographic interpretation of bony defects prepared with No.2 round bur was easier than those prepared with No. 1 round bur at 80-85kVp in periapical region (p<0.05). However, in cancellous bone, this radiographic interpretation was easier at 65-75kVp (p<0.05). There were significant differences in the radiographic interpretation between the defects confined only to the cancellous, bone and the defects involved in the compact bone (p<0.05). However there were no significant differences between the defects confined only to the cancellous bone and the defects involved in junctional area of cancellous and compact bone (p>0.05). From the results of densitometric analysis, there was a difference in densitometric measurements at the same radiographic interpretation scores, and aluminum equivalent differences of 0.15-1.66㎜ thickness were needed for radiographic interpretation.

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