• 대한의용생체공학회:의공학회지
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• 제28권3호
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• pp.397-409
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• 2007

Owing to needs of biomechanical comprehension and analysis to obtain various medical treatment designs which are related with the spine in order to cure and diagnose LBP patients, the FE modeling and nonlinear analysis of lumbosacrum including a partial ilium and iliolumbar ligaments, were carried out. First, we investigated whether the geometrical configuration of vertebrae displayed by DICOM slice files is regular and normal condition. After constructing spinal vertebrae including a partial ilium, a sacrum and five lumbars (from L1 to L5)with anatomical shape reconstructed using softwares such as image modeler and CAD modeler, we added iliolumbar ligaments, lumbar ligaments, discs and facet joints, etc.. And also, we assigned material property and discretized the model using proper finite element types, thus it was completely modeled through the above procedure. For the verification of each segment, average sagittal ROM, average coronal ROM and average transversal ROM under various loading conditions(${\pm}10Nm$), average vertical displacement under compression(400N), ALL(Anterior Longitudinal Ligament) and PLL(Posterior Longitudinal Ligament) force at L12 level, strains of seven ligaments on sagittal plane at L45 level and maximal strain of disc fibers according to various loading conditions at L45 level, etc., they were compared with experimental results. For the verification of multilevel-lumbosacrum spine including partial ilium and iliolumbar ligaments, the cases with and without iliolumbar ligaments were compared with ROM of experiment. The results were obtained from analysis of the verified FE model as follows: I) Iliolumbar ligaments played a stabilizing role as mainly posterior iliolumbar ligaments under flexion and as both posterior and anterior iliolumbar ligaments of one side under lateral bending. 2) The iliolumbar ligaments decreased total ROM of 1-8% in total model according to various motion conditions, which changed facet contact forces of L5S level by approximately 0.8-1.4 times and disc forces of L5S level by approximately 0.8-1.5 times more than casewithout ilioligaments, under various loading conditions. 3) The force of lower discs such as L45 and L5S was bigger than upper discs under flexion, left and right bending and left and right twisting, except extension. 4) It was predicted that strains of posterior ligaments among iliolumbar ligaments would produce the maximum 16% under flexion and the maximum 10% under twisting. 5) It's expected that this present model applies to the development and design of artificial disc, since it was comparatively in agreement with the experimental datum.

• Journal of Periodontal and Implant Science
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• 제34권1호
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• pp.71-81
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• 2004

Peri-implantitis could be the result of biomechanical and occlusal overload as well as microbiologic invasion. The dental implant may be more susceptible to dental plaque than the natural tooth, as the predictability of a stable soft tissue attachment complex has not yet been confirmed. With the development of peri-implantitis, the implant surface would be exposed to the oral environment and becomes coated with bacteria. The objective of therapy for this condition is to regain integration of the implant with bone. Since fibroblast adherence to surfaces is impeded by endotoxin, it would seem that decontamination would be desirable to obtain maximum osseointegration. The purpose of this study was to determine whether various chemotherapeutic and mechanical treatments(distilled water, air-powder abrasive, hypersaturated citric acid, tetracycline) can detoxify contaminated titanium implant surface by means of kinetic LAL test. Experimental rough surface titanium disks were fabricated. All of them were divided into two groups(A.a group and P.g group) and each contaminated by A. actinomycetemcomitans and P. gingivalis suspension. Contaminated disks were treated with distilled water, air-powder abrasive, citric acid and tetracycline, and then all disks were placed into LPS-free water for elution. The results were as follows : 1. In A.a group, LPS elute level of all test groups were significantly lower than control group(p<0.05). 2. In A.a group, LPS elute level of test 2, test 3 and test4 groups were significantly lower than that of control group(p<0.05). But, among the test 2, test 3, test4 groups, the significant differences were not detected. 3. In P.g group, LPS elute level of test 2, test 3 and test 4 groups were lower than that of control group(p<0.05). But, among the test groups, the significant differences were not detected. From the result of this study, it would be concluded that air-powder abrasive, hypersaturated citric acid and tetracycline treatments may be effective at reducing endotoxin level on rough titanium implant surfaces, and can be clinically used. But the treatments in peri-implantitis differentially impact osseointegration making one method clinically superior. To gain this knowledges, further molecular biologic and histopathologic studies should be developed.

• 대한치과보철학회지
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• 제58권2호
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• pp.161-168
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• 2020

임플란트 고정성 보철물의 실패는 과도한 교합스트레스와 같은 생역학적인 요인과 세균 감염, 염증과 같은 생물학적인 요인으로 인하여 일어난다. 임플란트 합병증으로 인한 문제가 해결되지 않고 악화되어 심한 골흡수가 일어난 임플란트는 제거되어야 하며, 제거 후 잔존 치아와 잔존 임플란트 및 잔존 치조제를 고려하여 새로운 치료를 계획해야 한다. 본 증례의 환자는 하악 무치악부에 약 10년 전 식립한 하악 고정성 임플란트 보철물 중 일부를 임플란트 주위염으로 인하여 제거하게 되었다. 추가 임플란트 재식립을 위한 잔존 치조골의 상태를 재평가 하고 소수의 임플란트를 추가 식립 후 임플란트 서베이드 크라운을 지대치로 하는 임플란트 융합 가철성 국소의치로 최종 치료하였다. 이를 통해 실패 이후 저작기능을 다시 회복하고 구강위생 관리에 유리한 조건으로 전환하였기에 이를 보고하고자 한다.

• 대한치과보철학회지
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• 제33권4호
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• pp.780-806
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• 1995

The purpose of this study was to describe the application of 3D finite element analysis to determine resultant stresses on the bone anchored fixed prosthesis, implants and supporting bone of the mandible according to fixture numbers and load conditions. 4 or 6 fixtures and the bone anchored fixed prosthesis were placed in 3D finite element mandibular arch model which represents an actual mandibular skull. A $45^{\circ}$ diagonal load of 10㎏ was labiolingually applied in the center of the prosthesis(P1). A $45^{\circ}$ diagonal load of 20㎏ was buccolingually applied at the location of the 10mm or 20mm cantilever posterior to the most distal implant(P2 or P3). The vertical distribution loads were applied to the superior surfaces of both the right and the left 20mm cantilevers(P4). In order that the boundary conditions of the structure were located to the mandibular ramus and angle, the distal bone plane was to totally fixed to prevent rigid body motion of the entire model. 3D finite element analysis was perfomed for stress distribution and deflection on implants and supporting bone using commercial software(ABAQUS program. for Sun-SPARC Workstation. The results were as follows : 1. In all conditions of load, the hightest tensile stresses were observed at the metal lates of prostheses. 2. The higher tensile stresses were observed at the diagonal loads rather than the vertical loads 3. 6-implants cases were more stable than 4-implants cases for decreasing bending and torque under diagonal load on the anterior of prosthesis. 4. From a biomechanical perspective, high stress developed at the metal plate of cantilever-to-the most distal implant junctions as a consequence of loads applied to the cantilever extension. 5. Under diagonal load on cantilever extension, the 6-implants cases had a tendency to reduce displacement and to increase the reaction force of supporting point due to increasing the bendign stiffness of the prosthesis than 4-implants cases. 6. Under diagonal load on cantilever extension, the case of 10mm long cantilever was more stable than that of 20mm long cnatilever in respect of stress distribution and displacement. 7. When the ends of 10mm or 20mm long cantilever were loaded, the higher tensile stress was observed at the second most distal implant rather than the first most distal implant. 8. The 6-implants cases were more favorable about prevention of screw loosening under repeated loadings because 6-implants cases had smaller deformation and 4-implants cases had larger deformation.

• 한국운동역학회지
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• 제31권1호
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• pp.72-78
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• 2021

Objective: The purpose of this study was to investigate relations and effectiveness about mountain climbling exercise with different level of support surfaces by analyzing heart rate and EMG data. A total of 10 male college students with no musculoskeltal disorder were recruited for this study. Method: The biomechanical analysis was performed using heart rate monitor (Polar V800, Polar Electro Oy, Finland), step-box, exercise mat, and EMG device (QEMG8, Laxtha Inc. Korea, sampling frequency = 1,024 Hz, gain = 1,000, input impedance > 1012 Ω, CMRR > 100 dB). In this research, step-box were used to create different surface levels on the upper body (flat surface, 10% of subject's height, 20% of subject's height, and 30% of subject's hight). Based on these different conditions, data was collected by performing mountain climbing exercise during 30 seconds. Subjects were given 5 minutes of break to prevent muscular fatigue after each exercise. For each dependent variable, a one-way analysis of variance with repeated measures was conducted to find significant differences and Bonferroni post-hoc test was performed. Results: The results of this study showed that exercise intensity was reduced statistically as increased surface level on the upper body. Muscle activity of the upper rectus abdominis and biceps femoris for 30% of surface level was significantly higher than the corresponding values for flat surface. However, the opposite was found in the rectus femoris. In general, muscle activity of the lower rectus abdominis, erector spinae, external oblique abdominis, and gluteus maximus increased when surface level increased, but the differences were not significant. Conclusion: As a result, the increase in surface level of the body would change muscle activity of the upper body, indicating that different surface level of the upper body may cause significant effect on particular muscles to be more active during mountain climbing exercise. Based on results of this study, it is suggested to set up an appropriate surface level to target particular muscle to expect an effective training. It is also important to set adequate surface levels to create an effective training condition for preventing exercise injuries.

• 구강회복응용과학지
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• 제36권4호
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• pp.222-231
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• 2020

안착형 외부 연결 임플란트를 적절히 사용하기 위해서는 식립 시에 임플란트 간의 간격에 주의해야 하며 2차 수술 시에 임플란트 상부로 올라간 골을 다듬어야 한다. 육각형태를 가진 지대주가 원형 지대주에 비해 유용하다. 외부 연결형 임플란트는 악간간격이 제한된 경우에 적용할 수 있다. 안착형 외부연결(조직수준) 임플란트는 상부 직경의 두께로 인한 생역학적 장점과 내재된 점막관통부로 인한 생물학적 장점을 가지고 있다. 조직수준 임플란트를 수복할 때 지대주 수준과 임플란트 수준의 변연 중 악간공간에 따라 선택한다. 어떤 한 가지 임플란트 종류로는 모든 증례를 만족시키기 어려우므로 교합력 및 골조건을 고려하여 적절한 임플란트를 선택하는 것이 필요하다.

• 대한치과보철학회지
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• 제53권2호
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• pp.120-127
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• 2015

목적: 4종의 임플란트 나사산이 골유착 중간과정과 완료 이후 단계에서 보이는 응력분산 특성을 평가하고자 한다. 재료 및 방법: 실린더형 몸체(외경 4.1 mm 길이 10 mm)에 이전연구에서 식립 특성이 우수하게 평가되었던 V-자형 나사산과 다른 3종(buttress형, reverse buttress형, square형)의 나사산을 가진 4종의 임플란트가 악골에 매식된 복합체 모델을 CAD 프로그램으로 제작하였다. 지대주 상부에 100 N의 힘을 임플란트 장축과 30도 방향으로 부하하고 인접골 응력분포를 유한요소 해석하였다. 응력분산 특성이 골유착 진척 상태에 따라 달라질 수 있다는 가정하에 임플란트/골 계면을 골유착 미숙단계와 골유착 완료단계의 두 가지로 구분하여 분석하였다. 골유착 미숙단계는 임플란트/골 계면을 비선형 contact 조건(마찰계수 0.3)으로 모사하였고, 골유착이 완료된 단계에 대해서는 계면이 충분히 결합된 것으로 간주하여 접합(bonding) 조건을 부여하였다. 결과: 골유착 정도에 따라 임플란트의 응력분산 특성이 달라졌다. 골유착 미숙단계에서는 골응력과 나사산에 따른 응력 특성의 차이도 상대적으로 컸고 골유착 완료단계에서는 골응력의 절대값과 나사산간 차이가 모두 감소하였으며, V-자형 나사산의 응력분산 특성은 골유착 미숙 및 완료단계에서 모두 4종 나사산의 중간 정도였다. 이로부터 나사산 디자인의 차이는 임플란트 식립후 골유착이 진행되는 과정까지 영향을 미치며, 일단 골유착이 완료되면 나사산의 영향은 급격히 감소할 것임을 추론할 수 있었다. 결론: V-자형 나사산의 응력분산 특성은 골유착이 이루어지는 단계와 완료된 이후 단계 전기간 동안 4종 나사산의 중간 정도였다.