• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.173.2-173.2
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• 2005

• 대한치과보철학회지
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• 제42권1호
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• pp.83-93
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• 2004

Statement of problem : Since the concept of osseointegrated dental implant by $Br{\aa}nemark$ et al was first applied to mandibular full edentulous patients. Recently it is considerated the first treatment option on missing teeth. A common problem associated with dental implant restorations is loosening of screws that retain the prosthesis to the abutment and the abutment to the implant fixture. Purpose : This study is to examine the influence on screw loosening of implant-abutment designs. Material and methods : External hex, cone screw, beveled hex, cam cylinder, cylinder hex by means of evaluating the loosening torques, with respect to a range of tightening torques after repeated loading. Result : 1. Cone screw, beveled hex groups are the highest initial tightening rate and cylinder hex, external hex groups are the lowest initial tightening rate (p < 0.05). 2. Cone screw groups are the highest after repeated loading tightening rate and cylinder hex groups are lowest after repeated loading tightening rate(p < 0.05). 3. Cone screw groups have the highest initial stability and anal stability. 4. All groups are decreased tightening rate after repeated loading.

• Smart Structures and Systems
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• 제15권1호
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• pp.41-55
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• 2015

This study proposes a laser based impedance measurement system and impedance based pipe corrosion and bolt-loosening monitoring techniques under temperature variations. For impedance measurement, the laser based impedance measurement system is optimized and adopted in this paper. First, a modulated laser beam is radiated to a photodiode, converting the laser beam into an electric signal. Then, the electric signal is applied to a MFC transducer attached on a target structure for ultrasonic excitation. The corresponding impedance signals are measured, re-converted into a laser beam, and radiated back to the other photodiode located in a data interrogator. The transmitted impedance signals are treated with an outlier analysis using generalized extreme value (GEV) statistics to reliably signal off structural damage. Validation of the proposed technique is carried out to detect corrosion and bolt-loosening in lab-scale carbon steel elbow pipes under varying temperatures. It has been demonstrated that the proposed technique has a potential to be used for structural health monitoring (SHM) of pipe structures.

• The Journal of Advanced Prosthodontics
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• 제7권5호
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• pp.375-379
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• 2015

PURPOSE. The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. MATERIALS AND METHODS. Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at $10^6$ cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). RESULTS. The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). CONCLUSION. The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.

• 한국전산구조공학회논문집
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• 제32권4호
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• pp.265-272
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• 2019

본 연구에서는 영상기반 딥러닝 및 이미지 프로세싱 기법을 이용한 볼트풀림 손상검출 기법을 제안하였다. 이를 위해 먼저, 딥러닝 및 이미지 프로세싱 기반 볼트풀림 검출 기법을 설계하였다. 영상기반 볼트풀림 검출 기법은 볼트 이미지 검출 과정 및 볼트풀림 각도 추정 과정으로 구성된다. 볼트 이미지의 검출을 위하여 RCNN기반 딥러닝 알고리즘을 이용하였다. 영상의 원근왜곡 교정을 위해 호모그래피 개념을 이용하였으며 볼트풀림 각도를 추정을 위하여 Hough 변환을 이용하였다. 다음으로 제안된 기법의 성능을 검증을 위하여 거더의 볼트 연결부 모형을 대상으로 볼트풀림 손상검출 실험을 수행하였다. 다양한 원근 왜곡 조건에 대하여 RCNN 기반 볼트 검출기와 Hough 변환 기반 볼트풀림 각도 추정기의 성능을 검토하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.636-641
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• 2007

This research focuses on the development of an analytical model loosening mechanism of dental implant system. The model is utilized for predictions of preload values for internal and external types of implants. It identifies the effects of various parameters such as friction, geometric factors and mechanical properties on the loosening mechanism of the implant system. The results of analytical model are compared to those of the numerical method for validation.

• 생약학회지
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• 제10권3호
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• pp.119-124
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• 1979

Both wild peony and cultivated peony demonstrated a slight effect and tranquilizer of anti-convulsion on the strychinine and picrotoxine but the wild plant was more effective. The methanol extract of cultivated peony root demonstrated a weak effect of muscle loosening but its mixture with water extractable fraction did not have this effect in contrast to the case wild type whose methanol extract mixture with water extractable fraction still retained a strong anti-convulsional muscle loosening effect. Therefore, it is concluded that wild peony root has more analgesic and muscle loosening effect than the cultivated counterpart has.

• 한국정밀공학회지
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• 제20권6호
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• pp.214-221
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• 2003

Tension mask assembly is positioned right behind the glass-made front panels of CRT type display devices. The frame-supported thin metal sheet contains numerous slits, through which electron beams are focused to enhance definition. Pretension is imposed on the masks, especially for enlarged flat screens, in order to avoid vibration due to acoustic or mechanical impact. High temperature assembly process subsequent to pretensioning, however, degenerates the creep resistance of common mask materials, and if tensile stress is high enough, tension on the mask may be loosened substantially due to creep deformation. In this study, the assembly is modeled as a combined structure of beams and wire array, and a numerical simulation is attempted for pretensioning followed by high temperature process. According to a model study, small amount of creep strain is likely to be generated, but its adverse influence is not negligible. Some structural modification measures to reduce the creep-induced tension loosening are proposed and evaluated. Also, optimal configuration of frame structure is sought for, which maintains high tension of masks and minimizes the possible creep of frame simultaneously.

• Journal of Yeungnam Medical Science
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• 제21권1호
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• pp.1-11
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• 2004

Total knee arthroplasty has become a common procedure for treatment of severe osteoarthritis, rheumatoid arthritis and post-traumatic arthritis. In the past, failure of total knee arthroplasty was commonly attributable to aseptic loosening, often associated with component malalignment, soft tissue imbalance. With improved surgical instrumentation and soft tissue balancing techiniques, failure secondary to mechanical loosening has been minimal. But surgeons are still dissatisfied with implant malalignment. Correct tibiofemoral alignment seems to be particularly important since it is generally agreed that axial deviation and imprecise implantation may lead to loosening of the implant component. Navigation systems and robotic techniques could potentially solve problems of imprecision in traditional total knee arthroplasty. It is expected that the success rate and longevity of total knee arthroplasty will be improved during the twenty first century.

• Clinics in Shoulder and Elbow
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• 제23권3호
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• pp.152-155
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• 2020

Periprosthetic fracture after total elbow replacement surgery is a difficult complication to manage, especially when it comes together with implant loosening. If stem revision and internal fixation of the periprosthetic fracture are performed simultaneously, this would be a very challenging procedure. Most of total elbow replacement implants are cemented type. Cement usage at periprosthetic fracture site may interfere healing of fractured site. Authors underwent internal fixation with use of locking plate and cerclage wire for periprosthetic fracture, allogenous fibular strut bone inserted into the humerus intramedullary canal allowing the fractured site to be more stable without cement usage. At 10-month follow-up, the complete union and good clinical outcome was achieved. We present a novel technique for treating periprosthetic fracture with implant loosening after total elbow replacement surgery, using intramedullary allogenous fibula strut bone graft.