• 한국가스학회지
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• 제11권4호
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• pp.79-84
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• 2007

LPG 용기에 장착된 네크링의 암나사와 개폐밸브의 수나사 사이에서 발생되는 접촉법선응력과 von Mises 응력을 유한요소법으로 해석하여 밸브나사의 체결안전성에 관련된 강도 및 가스누출 안전성에 대해 고찰하였다. LPG 봄베의 가스충전압력 $8{\sim}9kg/cm^2$은 밸브와 LP가스 용기의 체결작용과 밀봉작용을 담당하는 나사부에 가압된다. 나사 선단부에서 발생한 스크래치 마모나 칩핑 손상은 나사의 접촉높이를 실질적으로 낮추게 되어 나선부의 강도를 떨어뜨리고, LP가스의 누설을 조장하게 된다. 체결 나선부의 손상은 밸브 나사부의 이빨 강도를 약화시키고, LP가스의 누출에 영향을 미친다. FEM 해석결과에 의하면, 나사 선단부의 마모 및 칩핑에 의한 높이 손상은 이론적으로 볼 때 LP가스의 누출과 밸브의 강도에 영향을 미치지 못하는 것으로 나타났다. 그러나 황동밸브 나사 높이의 손상정도가 밸브의 임계강도를 넘어서게 되면, 나사는 밸브와 LP가스 봄베를 더 이상 체결하지 못하게 되어 압력용기는 갑자기 파손될 수도 있다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.16.1-16.6
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• 2017

Background: Mandibular reconstruction is performed after segmental mandibulectomy, and precise repositioning of the condylar head in the temporomandibular fossa is essential for maintaining preoperative occlusion. Methods: In cases without involvement of soft tissue around the mandibular bone, the autopolymer resin in a soft state is pressed against the lower border of the mandible and buccal and lingual sides of the 3D model on the excised side. After hardening, it is shaved with a carbide bar to make the proximal and distal parts parallel to the resected surface in order to determine the direction of mandibular resection. On the other hand, in cases that require resection of soft tissue around the mandible such as cases of a malignant tumor, right and left mandibular rami of the 3D model are connected with the autopolymer resin to keep the preoperative position between proximal and distal segments before surgical simulation. The device is made to fit the lower border of the anterior mandible and the posterior border of the mandibular ramus. The device has a U-shaped handle so that adaptation of the device will not interfere with the soft tissue to be removed and has holes to be fixed on the mandible with screws. Results: We successfully performed the planned accurate segmental mandibulectomy and the precise repositioning of the condylar head by the device. Conclusions: The present technique and device that we developed proved to be simple and useful for restoring the preoperative condylar head positioning in the temporomandibular fossa and the precise resection of the mandible.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제40권
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• pp.35.1-35.7
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• 2018

Background: After the resection at the mandibular site involving oral cancer, free vascularized fibular graft, a type of vascularized autograft, is often used for the mandibular reconstruction. Titanium mesh (T-mesh) and particulate cancellous bone and marrow (PCBM), however, a type of non-vascularized autograft, can also be used for the reconstruction. With the T-mesh applied even in the chin and angle areas, an aesthetic contour with adequate strength and stable fixation can be achieved, and the pores of the mesh will allow the rapid revascularization of the bone graft site. Especially, this technique does not require microvascular training; as such, the surgery time can be shortened. This advantage allows older patients to undergo the reconstructive surgery. Case presentation: Reported in this article are two cases of mandibular reconstruction using the ready-made type and custom-made type T-mesh, respectively, after mandibular resection. We had operated double blind peer-review process. A 79-year-old female patient visited the authors' clinic with gingival swelling and pain on the left mandibular region. After wide excision and segmental mandibulectomy, a pectoralis major myocutaneous flap was used to cover the intraoral defect. Fourteen months postoperatively, reconstruction using a ready-made type T-mesh (Striker-Leibinger, Freibrug, Germany) and iliac PCBM was done to repair the mandible left body defect. Another 62-year-old female patient visited the authors' clinic with pain on the right mandibular region. After wide excision and segmental mandibulectomy on the mandibular squamous cell carcinoma (SCC), reconstruction was done with a reconstruction plate and a right fibula free flap. Sixteen months postoperatively, reconstruction using a custom-made type T-mesh and iliac PCBM was done to repair the mandibular defect after the failure of the fibula free flap. The CAD-CAM T-mesh was made prior to the operation. Conclusions: In both cases, sufficient new-bone formation was observed in terms of volume and strength. In the CAD-CAM custom-made type T-mesh case, especially, it was much easier to fix screws onto the adjacent mandible, and after the removal of the mesh, the appearance of both patients improved, and the neo-mandibular body showed adequate bony volume for implant or prosthetic restoration.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권5호
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• pp.559-566
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• 2007

Distraction osteogenesis(DO) is a surgical method of bone formation that involves an osteotomy and sequential stretching of the healing callus by gradual movement and subsequent remodeling. DO is used to correct facial asymmetry, such as in patients with hemifacial microsomia, maxillary or mandibular retrusion, cleft lip and palate, alveolar defects, and craniofacial deficiency. It is accomplished with the aid of a distraction device, which is secured with screws placed directly into bone, for a predetermined length of time. Hemifacial microsomia is characterized by unilateral facial hypoplasia, often with unilateral shortening of the mandible and subsequent malocclusion. Patients with hemifacial microsomia and facial asymmetry have a vertically short maxilla, tilted occlusal plane, and short mandible. Early treatment is necessary to avoid subsequent impaired midfacial growth. The standard treatment of these malformations consists of the application of bone grafts, which can lead to unpredictable growth. The new bone-lengthening procedure represents a limited surgical intervention and opens up a new perspective for treatment, especially in younger children with severe deformities. This report describes a case of hemifacial microsomia(Type-II left-sided hemifacial microsomia). The patient, a 10-year-old child, visited our clinic for facial asymmetry correction. He had a hypoplastic mandible, displaced ear lobe, 10 mm canting on the right side, and malocclusion. We planned DO to lengthen the left mandible in conjunction with a Le Fort I osteotomy for decanting and then perform a right intraoral vertical ramus osteotomy(IVRO). Progressive distraction at a rate of 0.5 mm/12 hours was initiated 7 days postoperatively. The duration of DO was 17 days. The consolidation period was 3 months. Satisfactory results were obtained in our case, indicating that DO can be used successfully for functional, aesthetic reconstruction of the mandible. We report a case involving DO in conjunction with orthognathic surgery for correcting mandibular hypoplasia with a review of the literature.

• 한국초등과학교육학회지:초등과학교육
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• 제35권1호
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• pp.26-38
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• 2016

The purpose of this study was to grasp the characteristics of composition regarding the material-centered integrated unit of environmental and natural studies, a science subject in Finland, to investigate a need for applying the material-centered integrated unit to the science curriculum of Korea. For the purpose, the study made an analysis on contents, inquiry activities, and visual materials (the most important in the elementary science curriculum and textbook composition), and it brought following results: First, as a result of analyzing the area of contents, the bicycle material-centered integrated unit comprised a large proportion of 44 pages (25.3%) of the whole 174 pages from the environmental and natural studies textbook for the third grade. The contents included such various concepts as traffic rules, safety, environmental protection and pollution, recycling and separate collection, tubes and triangular structures, wedges and screws, leverage, wheels, axles, gears, elasticity (spring), friction, and so on. Second, as a result of analyzing contents related to the thinking ability of inquiry activities, "expecting or confirming expectations" and "application" are included in every lesson, and one lesson is composed in such a way that students can study on bicycles as a practical material for their daily life and they can improve various thinking abilities. Third, as a result of analyzing the circumstances of inquiry activities, daily circumstances made up eight lessons (80.0%) and technical and social circumstances made up two lessons (20.0%) by focusing on bicycles, a material related to students' daily life. Fourth, as a result of analyzing visual materials, the percentage of pictures and photos was high at 53.4% and 45.2% respectively. As a result of analyzing the role of visual materials, the percentage of the illustrative role and explanatory-complementary role was high at 52.1% and 47.9% respectively. Lastly, as a result of analyzing from the epistemological view to interpret the relation between visual materials and students and the position of visual materials, the visual textbook materials were provided toward a way that students can decrease their feeling of epistemological separation in the three fields of ideational metafunction, interpersonal metafunction, and textual metafunction.

• 대한방사선기술학회지:방사선기술과학
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• 제33권4호
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• pp.335-340
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• 2010

T형 금속판을 이용한 요골 원위부 골절 수술 후 나사못의 요골구 관통 유무를 확인하기 위한 요골구 촬영 방법을 알아보고자 하였다. Wrist CT 환자 51명의 3D 영상과 건조된 요골 표본 20본에서 요골구 각도를 분석하였고, 석고를 이용하여 요골 모형을 제작 한 다음 나사못이 요골구를 2.4 mm 관통 하도록 하고 요골구 원위부 거상 각도 및 외회전 각도를 0~30도까지 5도씩 변화시켜 X-선 영상으로 촬영하였다. 그 결과 요골구 각도는 Wrist CT 영상에서 평균 14.4도, 건조된 요골 표본에서 평균 16.3도였다. 요골 모형에서 요골구를 관통한 나사못의 길이는 거상 각도 및 외회전 각도에 따라 묘출 정도가 다름을 알 수 있었다. 결론적으로 T형 금속판을 이용한 요골 원위부 골절 수술 후 나사못의 요골구 관통을 알기 위한 접선방향촬영에서 요골 원위부 거상각은 $5^{\circ}$, 외회전 각은 $20^{\circ}$를 추천한다.

• 한국임상수의학회지
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• 제31권6호
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• pp.527-530
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• 2014

7살 중성화된 수컷 한국집 고양이가 6개월동안 지속된 변비를 주증으로 본원에 내원하였다. 직장검사에서 골반강의 우측 외측부분의 좁아짐을 보였고, 방사선검사에서는 골반골절의 부정유합으로 인한 골반강의 협착을 확인할 수 있었다. 골반강 직경 비율은 0.68이었다. 직장검사와 방사선검사를 기반으로 골반강 협착으로 인한 변비로 진단하였다. 그래서 골반결합을 절골하여 골반강 확장술을 시행하였고 이를 용이하게 하기 위하여 장골 절골술도 함께 시행하였다. 확장된 골반강을 유지하기 위하여 골반결합 사이에 폴리메칠메타크릴레이트를 성형하여 구조물로 삽입하였다. 절골 한 장골은 뼈판과 나사를 이용하여 다시 고정시켜주었다. 방사선 검사에서 술 후 골반강 직경 비율은 0.91로 증가했음을 알 수 있었다. 술 후 처치로는 항생제, 진통소염제, 락툴로오스경구제 투여와 함께 수액요법을 시행하였다. 환자는 골반강 확장술 후 일주일부터 정상적인 배변을 보였고, 그 이후 6개월동안 재발은 없었다. 이 증례를 바탕으로 골반강 확장술은 골반골절의 부정유합으로 인한 골반강 협착에 따라 발생한 변비에서 유용한 치료법으로 사료된다.

• 대한의용생체공학회:의공학회지
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• 제27권5호
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• pp.210-217
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• 2006

Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.

• Journal of Korean Neurosurgical Society
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• 제61권6호
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• pp.680-688
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• 2018

Objective : To mitigate the risk of iatrogenic instability, new posterior decompression techniques able to preserve musculoskeletal structures have been introduced but never extensively investigated from a biomechanical point of view. This study was aimed to investigate the impact on spinal flexibility caused by a unilateral laminotomy for bilateral decompression, in comparison to the intact condition and a laminectomy with preservation of a bony bridge at the vertebral arch. Secondary aims were to investigate the biomechanical effects of two-level decompression and the quantification of the restoration of stability after posterior fixation. Methods : A universal spine tester was used to measure the flexibility of six L2-L5 human spine specimens in intact conditions and after decompression and fixation surgeries. An incremental damage protocol was applied : 1) unilateral laminotomy for bilateral decompression at L3-L4; 2) on three specimens, the unilateral laminotomy was extended to L4-L5; 3) laminectomy with preservation of a bony bridge at the vertebral arch (at L3-L4 in the first three specimens and at L4-L5 in the rest); and 4) pedicle screw fixation at the involved levels. Results : Unilateral laminotomy for bilateral decompression had a minor influence on the lumbar flexibility. In flexion-extension, the median range of motion increased by 8%. The bone-preserving laminectomy did not cause major changes in spinal flexibility. Two-level decompression approximately induced a twofold destabilization compared to the single-level treatment, with greater effect on the lower level. Posterior fixation reduced the flexibility to values lower than in the intact conditions in all cases. Conclusion : In vitro testing of human lumbar specimens revealed that unilateral laminotomy for bilateral decompression and bone-preserving laminectomy induced a minor destabilization at the operated level. In absence of other pathological factors (e.g., clinical instability, spondylolisthesis), both techniques appear to be safe from a biomechanical point of view.

• 대한관절경학회지
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• 제4권2호
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• pp.148-153
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• 2000

목적 : 관절경하 족근관절 고정술의 결과를 분석하여 그 유용성을 보고하고자 한다. 대상 및 방법 : 1992년 10월부터 1996년 8월까지 족근관절 동통으로 관절경하 족근관절 고정술을 시행받은 5명, 6례를 대상으로 하였으며, 3례는 류마토이드 관절염, 2례는 퇴행성 관절염 그리고 1례는 결핵성 관절염이었다. 연령은 최저 38세에서 최고 65세로 평균 48세였으며, 남자 1명, 여자 4명이었다. 추시기간은 최단 12개월에서 최장 80개월로 평균 45개월이었다. 수술 방법은 경골과 종골의 외측부에 외고정장치를 부착하여 신연시킴으로써 족근관절강을 넓게 하여 관절경 및 수술기구를 사용할 수 있는 공간을 확보하였으며 전외측, 전내측 및 전면중앙의 입구를 사용하였다. shaver와 burr를 사용하여 경골, 거골 및 비골의 관절연골 및 연골하 뼈의 일부를 제거하고 출혈을 확인하였으며 경골 내과 및 비골 외과 상방에서 $2\~3$개의 유관나사(cannulated screws)를 사용하여 압박 고정하였다. 술 후 $6\~12$주간 단하지 석고 고정을 시행하였다. 결과 : 전례에서 족근관절의 유합소견을 보였으며 방사선 사진상 골유합의 시기는 최단 6주에서 최장 15주로 평균 10주였고 합병증은 발생하지 않았다. 결론 : 관절경하 족근관절 고정술은 류마토이드 관절염, 퇴행성 관절염 및 비교적 관절에 국한된 감염이 있는 환자에서 족근관절 고정술이 적응이 될 시 사용할 수 있는 좋은 방법으로 사료된다.