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Sandblasted large grit, acid etched 표면처리에 따른 교정용 미니 임플랜트의 제거회전력에 관한 연구
오남희,김성훈,국윤아,이근혜,강윤구,모성서 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.5
Sandblasted large grit, acid etched(SLA) 표면처리 된 교정용 미니 임플랜트와 평활면을 가진 교정용 미니 임플랜트 사이에 제거회전력과 조직학적 소견을 통해 표면처리된 교정용 임플랜트의 임상적 가능성에 대하여 알아보고자 하였다. 실험재료로는 길이가 9.5 mm, 외경이 1.8 mm인 custom made, screw shaped, titanium implants가 사용되었다. 미니 임플랜트는 두개의 군으로 분류되었는데 SLA군은 20개의 SLA 표면처리된 미니 임플랜트이었고, 평활면군은 크기와 형태가 같지만 SLA처리공정이 생략되어 제작된 20개의 미니 임플랜트로 구성되었다. 이들은 10마리 가토의 경골에 식립되었다. 각각의 가토의 우측 경골에는 SLA군의 미니 임플랜트 2개가 식립되었고, 좌측 경골에는 평활면군의 미니 임플랜트 2개가 식립되었다. 각 군에는 식립 직후 Ni-Ti coil spring에 의해 약 150 g의 지속적인 견인력이 주어졌다. 식립 6주 후에 10마리의 가토를 희생하였고, 안정된 상태에서 Ni-Ti coil spring을 제거하였으며 digital torque gauge를 이용하여 제거 회전력을 측정하였다. 식립 6주 후에 SLA군의 경우 (8.29 Ncm) 평활면군 (3.34 Ncm)에 비해 더 높은 평균 제거회전력을 나타내었고 조직학적 소견에서도 screw 하방에서의 신생골 형성이 관찰되었다. SLA 표면처리된 미니 임플랜트는 평활면 미니 임플랜트에 비해 좀 더 강한 교정력에 저항할 수 있을 것으로 예상되었다. Objective: The purposes of this study were to evaluate the differences between sand blasted, large grit and acid-etched (SLA) treated mini-implants and smooth surface orthodontic mini-implants in relation to the removal torque as well as the histologic analysis. Methods: Custom-made, screw-shaped, titanium implants with a length of 9.5 mm and an outer diameter of 1.8 mm were divided into 2 groups; the SLA group (20 SLA treated orthodontic mini-implants) and the smooth surface group (20 smooth surface mini-implants), and placed in the tibia metaphysis of 10 rabbits. Each rabbit had 4 mini-implants placed, 2 in each tibia. The right tibia were implanted with the SLA group mini-implants and the left tibia had the smooth group mini-implants placed. Each mini-implant group were immediately applied with a continuous traction force of 150 g using a Ni-Ti coil spring. The rabbits were sacrificed 6 weeks post-surgically. Subsequently, the legs were stabilized, the Ni-Ti coil springs were removed and the mini-implants were removed under reverse torque rotation with a digital torque gauge. Results: 6 weeks after placement, the SLA group presented a higher mean removal torque value (8.29 Ncm) than the smooth group (3.34 Ncm) and histologic analysis revealed a higher new bone formation aspect along the screw in the SLA group. Conclusion: Results of this study indicates that SLA treated mini-implants may endure higher orthodontic forces without loosening.
Nam-Goo Kang(Nam-Goo Kang),Jong-Gil Seo(Jong-Gil Seo),Won-Nyeong Cho(Won-Nyeong Cho),Jin-Wook Sung(Jin-Wook Sung) 한국임상움직임치료학회 2022 한국임상움직임치료학회지 Vol.2 No.2
Background Transverse abdominis (TrA) is an important local muscle that plays an essential role in the core. Ultrasound imaging is a reliable and valid technique for analyzing TrA muscle thickness. However, this method requires skilled operators. Biofeedback devices have achieved similar clinical outcomes to ultrasound. Even so, few studies have examined the validity of this biofeedback. Objectives This study aimed to assess whether changes in waist circumference, as determined by changes in the thickness of TrA detected with a stretch sensor made with a biofeedback device, produce results similar to those obtained through ultrasound. Methods Nineteen healthy participants were recruited for this study. Ultrasound measurement of the thickness of TrA was compared with the simultaneous measurement of the stretch sensor biofeedback device. Results Acceptable validity was found between the thickness of the TrA and the stretch sensor displayed on-screen waist circumference (Pearson correlation = -0.69, p = 0.03). Conclusions The study confirmed that changes in the grape bar on the screen of the stretch sensor application could be employed as a suitable indicator for assessing the changes to the thickness of the TrA muscle.
Goo, Nam Seo,Park, Hoon Cheol,Yoon, Kwang Joon Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.306 No.-
<P>A general helicopter uses rotary power produced from the installed engine in order to get the directional thrust. In the case of a tip-jet rotor helicopter, the compressed air or the combustion gas passes through a duct system inside rotors and is ejected out of the nozzle at the blade tips to produce torque enough for rotation of the rotor system. The generated torque makes the rotor system rotate, so that it can create the directional thrust. Since the anti-torque does not occur in this tip-jet rotorcraft, the tail rotor can be removed, which can be very attractive. In this paper, a power system for a reduced-scale tip-jet rotor by using a small turbo-jet engine is designed and tested for feasibility study. The in-plane thrust that the power system can produce is measured and compared with the calculated one. Finally, the finite element analysis of a conceptually designed tip-jet rotor is performed to ensure structural safety. </P>
Goo, Nam Seo,Phan, Van Phuoc,Park, Hoon Cheol Institute of Physics Publishing 2009 Smart materials & structures Vol.18 No.3
<P>Pre-stressed piezoelectric actuators such as RAINBOW, THUNDER™, and LIPCA have a curvature due to a mismatch of the coefficient of thermal expansion, which inevitably exists during the manufacturing process. This technical note provides an answer to the question of how their actuation displacement performance changes when the curved pre-stressed piezoelectric actuators are attached to a flat surface. Finite element analysis with the ANSYS™ program was used to calculate the stress distribution inside a LIPCA, one of the pre-stressed piezoelectric actuators, after the LIPCA was cured and attached to the flat surface. The change of actuation displacement performance can be explained in terms of the relation between the piezoelectric strain constants and internal stress. As a result of the curing and attachment to a flat surface, the two-dimensional stress state inside the piezoceramic layer leads to an expected increase of around 51% for the longitudinal piezoelectric strain constant. To confirm this result, we reconsider the experimental results of the actuation moment measurement of the LIPCA and bare lead zirconium titanate. </P>
The durability of a conducting shape memory polyurethane actuator
Goo, Nam Seo,Paik, Il Hyun,Yoon, Kwang Joon Institute of Physics Publishing 2007 Smart materials & structures Vol.16 No.4
<P>This paper discusses the actuation durability of a conducting shape memory polyurethane (CSMPU) actuator. Introduced in 2004, the CSMPU actuator was manufactured by an <I>in situ</I> polymerization method for shape memory polyurethane with multi-walled carbon nanotubes. In order to apply the CSMPU to smart actuators and determine detailed design concepts, the durability data should be measured. Hence, the experiments in this research were designed to obtain durability data, and the maximum number of actuation cycles versus the initial elongation ratio and the actuation temperature were measured for the purpose of assessing durability. The broken surfaces of the specimens were investigated. </P>
가열 요소를 이용한 형상기억폴리머 안테나 축소 모형의 전개 실험
구남서(Nam Seo Goo),안재균(Jae Kyun Ahn),김태균(Tae Kyun Kim),박미선(Miseon Park),박종규(Jongkyoo Park) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.10
우주 안테나용으로 연구 중인 열 자극 기반 형상기억폴리머로 된 축소 모형 안테나의 전개 실험을 수행하였다. 전개 실험을 위하여 양쪽 말단에 isocyanate기를 갖는 프리폴리머와 다관능기의 폴리올을 반응시켜 우레탄 형상기억폴리머를 합성하였으며, 2 mm의 두께를 갖는 원형 모양의 전개 시편을 제조하였다. 표면 부착형 가열 요소를 사용하여 형상기억폴리머 안테나 축소 모형을 전개한 결과, 가열요소의 크기와 방향 등에 따라 형상기억폴리머 시편의 온도 상승이 큰 차이를 나타내었다. 다양한 시도를 통하여 형상기억폴리머 시편을 전개시킬 수 있는 최적의 조건을 제시하였다. A deploying test of small-scale antenna models made of thermal stimulus-based shape memory polymer (SMP) was conducted; this material has been researched as a candidate for aerospace antenna applications. For the test, urethane SMP was synthesized from the prepolymer with diisocyanate and multi-functional polyol, and the circle-shaped specimens with a thickness of 2 mm were fabricated. The results of the deploying test of the SMP small-scale antenna model attached with heating element showed that the size and orientation of heating elements affect the temperature increase of the SMP specimens. The optimal attachment condition is suggested to deploy SMP effectively.