• 대한치과교정학회지
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• 제41권5호
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• pp.324-336
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• 2011

전치의 후방 견인 시 적절한 치아 이동 상태 조절은 필수적이다. 설측 장치를 이용한 레버 암 길이의 조절을 통하여 치아 이동에 관한 연구는 있었으나 3차원적인 변위 양상에 대한 연구는 많이 이루어지지 않은 실정이다. 이에 본 연구는 상악 전치부의 레버 암(lever arm)의 길이를 5 mm 단위로 20 mm까지 증가시켰으며 대구치와 TPA (trans palatal arch) 상에 있는 견인 훅(hook)의 위치를 달리 하여 200 gm의 후방 견인력을 가했을 때 나타나는 치아 변위 양상과 응력분포를 3차원적 유한요소분석을 통하여 알아보고자 하였다. 이를 위하여 아시아 성인의 표본조사를 통해 제작된 치아모형(Nissan Dental Product, Kyoto, Japan)을 3차원적으로 스캐닝한 후 상악치아, 치주인대, 치조골에 대한 유한요소 모델을 제작하였다. 각 치아의 절단연과 치근첨의 이동량을 x, y, z 좌표에서 각각 계산하여 치열의 변위 양상을 분석하고 von Mises 응력 분포를 계측하였다. 연구 결과, 정상 교합 모형의 레버 암 길이가 15 mm, 20 mm인 경우 전치 절단연과 치근첨의 설측 변위가 유도되었다. 본 실험의 조건 중 20 mm에서 치근첨의 설측 변위는 최대로 나타났다. 구치부 견인 훅이 치근첨에 있을 때 대구치 치관은 원심 방향으로 변위되었다. 또한 레버 암의 길이가 20 mm인 경우 전치부의 정출은 미약하였고 견치 치관은 협측 방향으로 전위되었다. 이 때 구치부 견인 훅의 위치가 TPA의 구개 중앙 측에 있을 때보다 가장자리 측에 있을 때 견치 치관은 더 많이 전위되었다. 이상의 결과를 토대로 설측 장치를 이용한 상악 6전치의 후방 견인 시 레버 암의 길이가 길고 구치부 견인 훅의 위치가 구개 중앙부에 있을 때 전치부 절단연(incisal edge)의 정출 없이 견치의 측방 전위 및 전치부 절단연과 치근첨의 설측 변위가 공히 나타남을 알 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제41권2호
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• pp.84-93
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• 2020

Despite of a lot of studies about proprioception tests, there are little study results to investigate the relationship between the functional movement and proprioception level. In this study, we tried to perform quantitative analysis for the effect of ankle joint proprioception level on the one leg standing postural control ability. Nine healthy people volunteered for this study. Force and position aspects of proprioception were evaluated using the electromyography system (EMG) and mobile clinometer application, respectively. The center of pressure (COP) trajectories, measured by a pressure mat sensor, were used for quantitative analysis of balance for each subject. We computed indices and errors of force and position aspects of proprioception from the EMG and ankle angle. Mean velocity of total and anterior-posterior direction (Vm and Vm_ap), root mean squared distance in anterior-posterior direction (RDap), travel length (L), and area (A) of COP trajectories were also calculated as indices of postural control ability of subjects. Two aspects of proprioception showed the low correlation from each other as previous studies. However, the EMG error of gastrocnemius lateral activation showed a high correlation coefficient with COP variables such as Vm (ρ=0.817, p=0.007), Vm_ap (ρ=0.883, p=0.002), RDap (ρ=0.854, p=0.003), L (ρ=0.817, 0.007) and A (ρ=0.700, p=0.036). Within our knowledge, this is almost the first study that investigated the relationship between proprioception level and functional movement. These study results could support that the ankle joint proprioception facilitation exercise would have positive effects on functional balance rehabilitation interventions.

• 대한소아치과학회지
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• 제26권1호
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• pp.38-43
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• 1999

치아전위는 비교적 드문 발육장애이다. 적절하게 차단치료된다면 예방이 가능할 뿐 아니라 이후의 교정과 수복과정이 보다 용이할 수 있다. 이를 위한 8-9세 경의 조기 임상검사가 이러한 발육장애의 인지를 위해 추천된다. 일단 전위가 일어난 경우에는, 부정교합을 교정하고 최상의 기능적, 심미적 결과를 얻기 위해 주의깊은 교정적 평가가 요구된다. 이상적인 결과를 얻기 위하여 두 치아를 원래의 위치로 환원시키는 치료가 요구되나, 완전전위되어 두 치아가 맹출되었다면 전위된 상태로 치아를 배열하여도 비교적 양호한 결과를 얻을 수 있었다.

• 대한소아치과학회지
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• 제42권1호
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• pp.87-101
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• 2015

하악 유견치의 조기탈락은 임상에서 흔히 관찰되는 현상으로 후에 영구치열에서 총생의 징후라 할 수 있으며 향후 영구 전치의 배열상의 문제점이나 부정교합을 유발할 수 있다. 영구 측절치가 맹출될 때 맹출 공간이 부족할 경우 인접해 있는 유견치 치근을 흡수시키면서 맹출하게 되고 그 결과 유견치가 조기에 탈락하게 되는데, 이 경우 영구 하악 영구 절치들이 설측으로 경사지게 되면 상악 절치들과 교합 접촉이 상실되어 상악 절치들이 과맹출됨으로써 수직피개교합 및 수평피개교합이 깊어지며 악궁둘레길이는 감소된다. 유견치가 편측으로 상실된 경우는 상기 현상 이외에, 영구 절치들이 조기 상실된 부위의 공간으로 경사지게 되어 정중선이 틀어지게 된다. 보통 4 mm 이하의 공간부족은 순차적인 유치의 disking과 passive lingual arch를 사용하여 leeway space를 보호하는 것만으로도 해결이 가능하며 4~6 mm 공간부족은 상기 술식과 함께 악궁의 전후방 및 측방확장으로 어느정도 해소할 수 있다.

• Archives of Plastic Surgery
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• 제35권3호
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• pp.273-278
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• 2008

Purpose: The most widely accepted protocol for alveolar cleft reconstruction is to repair it during the mixed dentition stage. There were lower resorption rate (about 88%) at this stage. However we found some cases that need repeated bone grafting. Therefore we sought to analyze the cause of repeated alveolar bone grafting in connection with other factors. Methods: From January 2000 to January 2006, thirty-nine secondary alveolar bone grafts with iliac crest spongiosa were carried out. In 39 patients, 5 patients who had significant bone graft resorption received repeated alveolar bone graft. In all the cases, the causes of repeated bone grafts were dental root exposure(angulation), and the deficiency of the bony support for lateral incisor or canine eruption. In 3 cases, there was deficiency of the alveolar bone at the cleft side. There was the need of repeated bone grafts for orthodontic treatment in 2 cases and for application of dental implants in 1 case. Results: During the follow-up period, the clinical and radiologic examinations showed that repeated alveolar bone grafts were maintained successfully without any complications. The volume of the repeated bone graft was sufficient for orthodontic treatment and implantation. Conclusion: The essential conditions for successful alveolar bone grafting includes the status of cleft sided teeth, further treatment and planed schedule, as well as canine eruption. Alveolar bone grafting has to be performed with difference of each case in mind.

• The Journal of Korean Physical Therapy
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• 제28권5호
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• pp.308-313
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• 2016

Purpose: This study investigated the effects of sex hormones across menstrual cycle phases on knee muscle activity during one-leg landing in non-athletic females. Methods: Twenty-six healthy females who reported normal menstrual cycles for the previous three months were tested when estrogen levels were highest (ovulation) and lowest (menstruation). Knee muscle activity was analyzed based on electromyography (EMG) data recorded during landing on a 30-cm box. Before data collection, each subject was trained in single-leg landing tasks ten times. Landing was analyzed by measuring the average of three landing tasks. EMG data were collected between the moment of ground contact and the point of knee maximum flexion. The maximum voluntary isometric contraction (MVIC) for normalization that was recorded as the EMG root-mean-square (RMS) during landing was tested, with paired t-tests used to assess differences in knee muscle activity according to menstrual cycle phases. Results: The results showed that the soleus, semitendinosus, and lateral gastrocnemius muscle activity during landing was differed significantly during ovulation compared to that during menstruation (p<0.05). No significant differences in vastus medialis activity were found between menstrual and ovulatory phases during landing (p>0.05). Conclusion: Changes in the menstrual cycle in response to sex hormones changed the activity of muscles around the knee during landing. Females utilize different muscle activity control strategies during different phases of the menstrual cycle, which may contribute to increased ACL injury risk.

• Journal of Korean Neurosurgical Society
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• 제48권2호
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• pp.139-144
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• 2010

Objective : We report our surgical experience in the treatment of 16 consecutive patients with benign craniovertebral junction (CVJ) tumor, observed from 2003 to 2008 at our department. Methods : We had treated 6 foramen magnum meningiomas, 6 cervicomedullary hemangioblastomas, 1 accessory nerve schwannoma, 1 hypoglossal nerve schwannoma, 1 C2 root schwannoma, and 1 cavernous hemangioma. Clinical results were evaluated by Karnofsky Performance Scale (KPS) and all patients underwent preoperative neuroradiological evaluation with computed tomography (CT) and magnetic resonance image (MRI). Angiography was performed in 15 patients and preoperative embolization was done in 2 patients. Results : Five far-lateral, 1 supracondylar and 10 midline suboccipital approaches were performed. Gross total removal was achieved in 15 cases (94%) and subtotal removal in 1 patient (6%). None of the patients required occipitocervical fusion. Radiological follow-up showed no recurrence in cases totally removed. Postoperative decrease of KPS scores was recorded in only 1 patient. The treatment of cervicomedullary solid hemangioblastoma presented particular issues : by preoperative embolization, we removed tumor totally without an excessive bleeding or brainstem injury. In one of foramen magnum meningioma, we carried out subtotal removal due to hard tumor consistency and encasement of neurovascular structures. Conclusion : The choice of surgical approaches and the extent of bone resection should be defined according to the location and size of individual tumors. Moreover, we emphasize that preoperative neuroradiological evaluations on presumptive tumor type could be helpful to the surgeon in tailoring the technique and providing the required exposure for different lesions, without unnecessary surgical steps.

• 대한두개안면성형외과학회지
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• 제11권1호
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• pp.65-68
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• 2010

Purpose: Dermoid cysts are benign neoplasms that are derived from both ectoderm and mesoderm. Approximately 7 percent of all dermoid cysts occur in the head and neck, as most common sites are the lateral ends of the eyebrows, the midline in the nasal root and neck. Rarely they can be found in the frontal sinus, temporal bone, maxilla and the floor of the mouth. Dermoid cysts in the temporal fossa are extremely rare. We experienced a characteristic dermoid cyst that occupied the temporal fossa. Methods: A 16-year-old man had a progressive enlarging mass on the left eyebrow. Computerized tomographic scan showed a bulging mass in the temporal fossa, and it had the density similar to that of fat. The size of the mass was $3{\times}3{\times}2cm$, and it was composed of high density of fat with clear margin. There was no bony invasion, but the mass was fixed on bone. Results: We performed the surgery through coronal incision under general anesthesia. Because the mass was closely connected with temporal fat pads, we removed this mass with some portion of temporal fat pads, avoiding damage to the facial nerve. The postoperative course was ordinary without complication. Conclusion: The reports about dermoid cyst on the temporal fossa is uncommon. However, if there is a mass in the temporal fossa which has the density similar to that of fat in CT scan, we should consider the possibility of dermoid cyst. We suggest that excision through coronal incision with bewaring temporal fat pad can induce good result.

• Advances in biomechanics and applications
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• 제1권3호
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• pp.169-185
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• 2014

Computational multibody models of the elbow can provide a versatile tool to study joint mechanics, cartilage loading, ligament function and the effects of joint trauma and orthopaedic repair. An efficiently developed computational model can assist surgeons and other investigators in the design and evaluation of treatments for elbow injuries, and contribute to improvements in patient care. The purpose of this study was to develop an anatomically correct elbow joint model and validate the model against experimental data. The elbow model was constrained by multiple bundles of non-linear ligaments, three-dimensional deformable contacts between articulating geometries, and applied external loads. The developed anatomical computational models of the joint can then be incorporated into neuro-musculoskeletal models within a multibody framework. In the approach presented here, volume images of two cadaver elbows were generated by computed tomography (CT) and one elbow by magnetic resonance imaging (MRI) to construct the three-dimensional bone geometries for the model. The ligaments and triceps tendon were represented with non-linear spring-damper elements as a function of stiffness, ligament length and ligament zero-load length. Articular cartilage was represented as uniform thickness solids that allowed prediction of compliant contact forces. As a final step, the subject specific model was validated by comparing predicted kinematics and triceps tendon forces to experimentally obtained data of the identically loaded cadaver elbow. The maximum root mean square (RMS) error between the predicted and measured kinematics during the complete testing cycle was 4.9 mm medial-lateral translational of the radius relative to the humerus (for Specimen 2 in this study) and 5.30 internal-external rotation of the radius relative to the humerus (for Specimen 3 in this study). The maximum RMS error for triceps tendon force was 7.6 N (for Specimen 3).

• Journal of Korean Neurosurgical Society
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• 제37권4호
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• pp.258-262
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• 2005

Objective: The 5th lumbar spinal nerve can be entrapped in the intraspinal zone, foraminal zone, and the extraforaminal zone simultaneously. The failure to recognize that the nerve root can be compressed in such manners may be the reason of a number of failures of surgical decompression. Here we describe a microsurgical method for the decompression of the triple entrapment of the L5 spinal nerve in 21 patients. Methods: Clinical manifestations and surgical results of twenty-one patients treated surgically under the diagnosis of the triple entrapment of the L5 spinal nerve were reviewed retrospectively. All patients were treated by the posterior midline approach for the intraspinal entrapment and by the paraspinal approach for the foraminal and the extraforaminal entrapment. Results: Pain relief was obtained in all patients immediately after surgery. The mean follow-up period after the surgery was 13 months, ranged from 6 to 24 months. The mean Numeric Rating Scale (pain score) improved from 8.9 before the surgery to 1.4 (P<0.0001). The mean ODI scores improved from 76.2 before the surgery to 13.1 (P<0.0001). Nineteen patients were satisfied with their result at the last follow-up examination. Neither complications related to the surgery, nor the spinal instability was detected. Conclusion: The triple entrapment of the 5th lumbar spinal nerve is an important pathologic entity to identify for the treatment of L5 radiculopathy. Combined medial and lateral approaches are safe, minimally invasive and it provide the complete decompression of triple entrapment of the L5 spinal nerve without causing secondary instability like after complete facetectomy.