• Advances in biomechanics and applications
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• 제1권2호
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• pp.77-83
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• 2014

Creep phenomenon at the scale of bone tissue (small specimens) is known to be present and demonstrated for low strains. Here creep is demonstrated on a pair of fresh-frozen human femurs at the organ level at high strains. Under a constant displacement applied on femur's head, surface strains at the upper neck location increase with time until fracture, that occurs within 7-13 seconds. The monotonic increase in strains provides evidence on damage accumulation in the interior (probably damage to the trabeculae) prior to final fracture, a fact that hints on probable damage of the trabecular bone that occurs prior to the catastrophic fracture of the cortical surface layer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.139-143
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• 2005

As increasing gastrointestinal pathologies, general and thoracic surgeries using circular staplers have been dramatically increased. Because of convenience for surgical procedure, recently, various circular staplers for anastomosis have been used widely. Since the circular staplers conventional have used the displacement control method, however, the anastomosis could have various biomechanical conditions. To do that, biomechanical system of gastrointestinal soft tissue should be examined to control the anastomotic condition. In this study, a new intelligent robot used in circular anastomosis. The intelligent robot driven by a stepper motor and controlled by a digital signal processor.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.39.1-39.20
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• 2018

Magnetic resonance imaging (MRI) is an advanced diagnostic tool used in both medicine and dentistry. Since it functions based on a strong uniform static magnetic field and radiofrequency pulses, it is advantageous over imaging techniques that rely on ionizing radiation. Unfortunately, the magnetic field and radiofrequency pulses generated within the magnetic resonance imager interact unfavorably with dental materials that have magnetic properties. This leads to unwanted effects such as artifact formation, heat generation, and mechanical displacement. These are a potential source of damage to the oral tissue surrounding the affected dental materials. This review aims to compile, based on the current available evidence, recommendations for dentists and radiologists regarding the safety and appropriate management of dental materials during MRI in patients with orthodontic appliances, maxillofacial prostheses, dental implants, direct and indirect restorative materials, and endodontic materials.

• Coupled systems mechanics
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• 제10권1호
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• pp.21-38
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• 2021

This work is an attempt to design a dynamic model for a non local bio-thermoelastic medium with diffusion. The system of governing equations are formulated in terms of displacement vector field, chemical potential and the tissue temperature in the context of non local dual phase lag (NL DPL) theories of heat conduction and mass diffusion. Based on this considered model, we study the fundamental solution and propagation of plane harmonic waves in tissues. In order to analyze the behavior of the NL DPL model, we construct basic theorem in the terms of elementary function which determine the existence of three longitudinal and one transverse wave. The effects of various parameters on the characteristics of waves i.e., phase velocity and attenuation coefficients are elaborated by plotting various figures of physical quantities in the later part of the paper.

• Steel and Composite Structures
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• 제38권4호
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• pp.447-462
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• 2021

In this work, we consider a problem in the context of thermoelectric materials with memory-dependent derivative for a half space which is assumed to have variable thermal conductivity depending on the temperature. The Lamé's modulii of the half space material is taken as a function of the vertical distance from the surface of the medium. The surface is traction free and subjected to a time dependent thermal shock. The problem was solved by using the Laplace transform method together with the perturbation technique. The obtained results are discussed and compared with the solution when Lamé's modulii are constants. Numerical results are computed and represented graphically for the temperature, displacement and stress distributions. Affectability investigation is performed to explore the thermal impacts of a kernel function and a time-delay parameter that are characteristic of memory dependent derivative heat transfer in the behavior of tissue temperature. The correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권3호
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• pp.178-181
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• 2022

Williams-Beuren syndrome (WS) is a rare genetic disorder that results from microdeletion at chromosome 7, which harbors the elastin gene. Clinical findings include arteriopathy, aortic stenosis, hypertension, and laxities and contractures in different joints throughout the body. While many components of the temporomandibular joint (TMJ) normally contain elastin, there are few reports on TMJ manifestations of WS. This study reports a TMJ ankylosis case in a WS patient and shares insight on a possible link between development of TMJ ankylosis and elastin deficiency in WS patients. A WS patient presented with bilateral TMJ ankylosis and was successfully treated with TMJ gap arthroplasty. Hypermobility of TMJ and lack of elastin in retrodiscal tissue can induce anterior disc displacement without reduction. Due to lack of elastin, which has a significant role in the compensatory and reparatory mechanism of TMJ, WS patients might be prone to TMJ ankylosis.

• Clinical and Experimental Pediatrics
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• 제48권8호
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• pp.846-856
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• 2005

목 적 : 최근 심장 기능 평가에 많이 사용되는 TDI 지표들에 대해서 우리나라의 정상 소아에 대한 연구가 아직 미흡한 실정이다. 이에 정상 소아 72례(남아 : 42례, 여아 : 30례)를 대상으로 한 TDI 및 31례를 대상으로 한 M-형 심초음파 검사를 이용한 지표들에 대한 계측치를 확인하고, 이러한 계측치에 여러 변수들(몸무게, 심박동수, 측정한 위치 등)이 미치는 영향에 대해서 관찰하였다. 방 법 : 선천성 심질환이나 심장에 영향을 미칠 수 있는 질환이 없는 건강한 소아를 대상으로 하여, 심첨 4방도, 심첨 2방도의 여러 부위에서 PW-TDI를 이용하여 최대 심근 속도를 측정하고, 측정 부위에 따른 계측치의 차이, 나이, 몸무게 및 심박동수 등이 이러한 측정치들에 미치는 영향에 대해서 연구하였다. 또한 심첨 4방도에서 각각의 판막륜 방향으로 M-형 심초음파 검사를 시행하여 나이, 몸무게 및 심박동수와 연관 관계가 있는지 알아보았다. 또한 M-형 심초음파 검사에서 측정한 값들과 TDI 계측치들과의 관계에 대해서도 연구하였다. 결 과 : TDI로 측정한 여러 변수들은 남녀, 심초음파 기기간 및 검사를 시행한 의사간에는 의미있는 차이를 보이지 않았다. 판막륜과 판막륜 및 심첨의 중간 부위에서 측정한 값간에는 판막륜에서 측정한 값들이 의미있게 높게 측정되었으며, 우심실 측벽의 측정치가 심실 중격 및 좌심실 부위에서 측정한 값보다 높았다. 심근 단축률과 TDI 측정치간에는 상관 관계를 보이지 않았다. 심박동수와의 상관 관계를 보면 S-및 E-파형의 경우 심박동수와 상관 관계가 없었으나, A-파형 및 A/E 비는 심박동수와 양의 상관 관계를 보였다. 몸무게와의 상관 관계도 측정한 부위 및 계측치 들마다 일정한 상관 관계를 보여 주지는 못하였다. M-형 심초음파 검사로 측정한 판막륜의 움직임은 성별간에 유의한 차이를 보이지 않았으며, ALD는 몸무게와 양의 상관 관계를, 이동률은 음의 상관 관계를 보이는 경향이 있었다. 그러나 이동률과 TDI 계측치들 간에는 유의한 상관 관계를 발견할 수 없었다. 결 론 : 정상 소아들에서 TDI를 이용하여 최대 심근 속도를 측정하고, 또한 M-형 심초음파 검사를 이용한 판막륜의 움직임을 관찰해 보았다. 이러한 계측치들을 토대로 좀더 많은 례를 통한 한국 소아들의 TDI 및 M-형 심초음파 검사를 이용한 판막륜의 움직임에 대한 정상치를 확립하여야 하겠으며, 선천성 및 후천성 심질환을 가진 환아들에서의 임상 적용을 기대해 본다.

• Archives of Plastic Surgery
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• 제37권1호
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• pp.37-45
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• 2010

Purpose: In Korean rhinoplasty, alloplasts such as silicone rubber have been used for dorsal and tip augmentations. However, alloplasts have produced complications such as deviation, exposure, and infection. Although autogenous tissue is an ideal material, the amount of the cartilage in Korean is not sufficient. Therefore, the authors developed a method to harvest the maximum amount of the septal and conchal cartilage. The authors first performed a complete septal extension graft for short and retruded columella and then performed nasal augmentation using various autogenous tissues. Methods: These surgical techniques were performed on 11 patients. Their average age was 27 years. An open approach with a V-shaped columellar labial incision was performed. At first, the complete septal extension graft was fixed on the entire caudal margin of the septum, and the alar cartilage was suspended to the septal extension graft to make the tip projected and the columella advanced caudally. A temporal fascial ball was used for radix augmentation. For dorsal augmentation, a batten-shaped septal cartilage graft wrapped with or without the temporal fascia or a diced cartilage graft wrapped with the temporal fascia was performed. For nasal tip augmentation, a shield graft and a cap graft or a folded conchal cartilage graft was performed.Results: The mean follow-up period was 11.2 months. The overall results were natural and satisfactory. Two patients underwent slight absorption and caudal displacement. With the exception of these cases, no complications were observed. Conclusion: Korean rhinoplastic surgeons are accustomed to using the alloplasts despite of serious complications. When rhinoplasty using autogenous tissue was performed, some complications occurred such as the displacement of the diced cartilage graft wrapped with the fascia, but many of the complications of alloplastic rhinoplasty were avoided. Therefore, we propose that by this time Korean rhinoplastic surgeons need to change their preference from alloplastic rhinoplasty to autogenous rhinoplasty.

• 한국임상수의학회지
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• 제34권6호
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• pp.414-419
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• 2017

The present study aimed to document the biomechanical findings of soft tissue reconstruction surgeries for the treatment of medial patellar luxation in dogs. Stifle joints (n = 12) from dogs weighing 4.1-8.4 kg were used in this study. The following soft tissue reconstruction techniques used for the treatment of medial patellar luxation were selected for this study: vastus medialis release, medial retinacular release, and capsule release for medial realignment (n = 6), and retinacular imbrication and anti-rotational suture for lateral realignment (n = 6). A 5-kg traction using an electronic scale was applied at $45^{\circ}C$ laterally for medial realignment and medially for lateral realignment. Fluoroscopic imaging was used to measure the length of patellar displacement (LPD) in each technique. Among medial realignment techniques, capsule release had the highest horizontal LPD; vastus medialis release had significantly higher horizontal LPD than medial retinacular release. Vastus medialis release had the smallest increase statistically in vertical LPD, and vertical LPD did not differ significantly between medial retinacular and capsule release. Among lateral realignment techniques, the horizontal LPD was significantly higher in anti-rotational suture with retinacular imbrication than in retinacular imbrication alone, but the vertical LPD did not differ significantly between the two groups. Our findings indicated that vastus medialis release could decrease the medial tension on the patella without inducing patellar instability in dogs. Both medial retinacular and capsule release could increase patellar instability; moreover, medial retinacular release does not decrease the medial tension on the patella. Antirotational suture with retinacular imbrication provides more lateral tension than retinacular imbrication alone.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제20권2호
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• pp.101-105
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• 1998

Compound comminuted mandibular fracture is defined as the presence of multiple fracture lines with open wound resulting in many small pieces within the same area. The incidence of mandibular comminution is difficult to determine but reported as 2.7~18.6 % incidence among mandibular fractures. There are controversies in the treatment of mandibular comminuted fractures. Treatment of comminuted mandibular fracture has traditionally involved closed reduction in an effort to avoid stripping periostcum from the bony segments, but rigid internal rigid fixation is used more popular at present. The extent of comminution, displacement of bony fragments and patient general conditions are important factors in decision of the treatment methods. When significant bone displacement is present, it is necessary to reduce these comminuted fragments to an anatomic, pretraumatic relationship to restore facial form and function. In these cases, ORIF allows anantomic reduction of comminuted segments as well as pretraumatic occlusion. Gentle handling of the soft tissue, rigid fixation of bony fragments and adequate immobilization are essential for reducing the complications. This is the report the incidence, causes, complications and treatment of the patients who visited our department for compound comminuted mandibular fractures.