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분절호선법으로 상하악 절치부 압하 시 순측경사도가 미치는 영향에 관한 3차원 유한요소법적 연구
김동우,양훈철,김기태,김성식,손우성 대한치과교정학회 2003 대한치과교정학회지 Vol.33 No.4
본 연구는 상하악 절치부의 압하를 도모하기 위한 장치의 하나인 분절호선장치를 사용하여 절치부의 순측경사에 따른 저항중심의 위치와 변화양상, 그리고 치축경사 개선과 압하를 동시에 이루기 위해 필요한 최소 후방 견인력의 크기 및 변화양상을 알아보기 위하여 3차원 유한요소법을 이용하여 시행되었으며 다음과 같은 결론을 얻었다. 1. 치축 경사도의 변화에 따른 상악 절치부 저항중심은 1) 정상 치축경사를 가진 경우에서 측절치 브라켓 원심면 후방 6mm에 위치하였다. 2) 순측경사가 10˚ 증가된 경우에서 측절치 브라켓의 원심면 후방 9mm에 위치하였다. 3) 순측경사가 20˚ 증가된 경우에서 측절치 브라켓 원심면 후방 12mm에 위치하였다. 4) 순측경사가 30˚ 증가된 경우에서 측절치 브라켓 원심면 후방 16mm에 위치하였다. 2. 치축 경사도의 변화에 따른 하악 절치부 저항중심은 1) 정상 치축경사를 가진 경우에서 측절치 브라켓 원심면 후방 10mm에 위치하였다. 2) 순측경사가 10˚ 증가된 경우에서 측절치 브라켓 원심면 후방 13mm에 위치하였다. 3) 순측경사가 20˚ 증가된 경우에서 측절치 브라켓 원심면 후방 15mm에 위치하였다. 4) 순측경사가 30˚ 증가된 경우에서 측절치 브라켓 원심면 후방 18mm에 위치하였다. 3. 응력 분포 양상은 1) 각 저항중심에서 압하력을 가한 경우에 치주인대에 균일한 압축응력을 나타내었다. 2) 후방 견인력을 동시에 적용한 경우에 순측경사가 증가할수록 응력분포 양상이 복잡해지는 양상을 보였다. 4. 상하악 절치부가 20˚까지 순측경사된 경우에서 pure intrusion을 위하여 필요한 후방 견인력의 크기도 증가하였다. This study was designed to investigate the position of anteroposterior center of resistance for genuine intrusion and the mode of change of the minimum distal force for simultanous intrusion and retraction of the upper and lower incisors according to the increase of labial inclination. For this purpose, we used the three-piece intrusion arch appliance and three-dimensional finite element models of upper and lower incisors. 1. Positions of the center of resistance in upper incisors according to the increase of the labial inclination were as follows; 1) In normal inclination situation, the center of resistance was located in 6mm behind the distal surface of the lateral incisor bracket. 2) In 10˚ increase of the labial inclination situation, the center of resistance was located in 9mm behind the distal surface of the lateral incisor bracket. 3) In 20˚ increase of the labial inclination situation, the center of resistance was located in 12m behind the distal surface of the lateral incisor bracket. 4) In 30˚ increase of the labial inclination situation, the center of resistance was located in 16m behind the distal surface of the lateral incisor bracket. 2. Positions of the center of resistance in lower incisors according to the increase of the labial inclination were as follows; 1) In normal inclination situation, the center of resistance was located in 10mm behind the distal surface of the lateral incisor bracket. 2) In 10˚ increase of the labial inclination situation, the center of resistance was located in 13mm behind the distal surface of the lateral incisor bracket. 3) In 20˚ increase of the labial inclination situation, the center of resistance was located in 15m behind the distal surface of the lateral incisor bracket. 4) In 30˚ increase of the labial inclination situation, the center of resistance was located in 18m behind the distal surface of the lateral incisor bracket. 3. The patterns of stress distribution were as follows; 1) There were even compressive stresses in and periodontal ligament when intrusion force was applied through determined center of resistance. 2) There were gradual increase of complexity in compressive stress distribution pattern with increase of the labial inclination when intrusion and retraction force were applied simultaneously. 4. With increase of the labial inclination of the upper and lower incisors, the position of the center of resistance moved posteriorly. And the distal force for pure intrusion was increased until 20˚ increase of the labial inclination.
Overcome the barriers of the skin: exosome therapy
Gi Hoon Yang,Yoon Bum Lee,강동구,Eunjeong Choi,Yoonju Nam,Kyoung Ho Lee,Hi Jin You,Hyo Jin Kang,안상현,전호준 한국생체재료학회 2021 생체재료학회지 Vol.25 No.3
Exosomes are nano-sized cargos with a lipid bilayer structure carrying diverse biomolecules including lipids, proteins, and nucleic acids. These small vesicles are secreted by most types of cells to communicate with each other. Since exosomes circulate through bodily fluids, they can transfer information not only to local cells but also to remote cells. Therefore, exosomes are considered potential biomarkers for various treatments. Recently, studies have shown the efficacy of exosomes in skin defects such as aging, atopic dermatitis, and wounds. Also, exosomes are being studied to be used as ingredients in commercialized skin treatment products. In this review, we discussed the need for exosomes in skin therapy together with the current challenges. Moreover, the functional roles of exosomes in terms of skin treatment and regeneration are overviewed. Finally, we highlighted the major limitations and the future perspective in exosome engineering.
Yang, Gi Hoon,Kim, Minseong,Kim, GeunHyung IOP Publishing 2017 Biofabrication Vol.9 No.1
<P>Three-dimensional biomedical polycaprolactone scaffolds consisting of microsized spiral-like struts were fabricated using an additive manufacturing process. In this study, various processing parameters such as applied pressure, polymer viscosity, printing nozzle-to-stage distance, and nozzle moving speed were optimized to achieve a unique scaffold consisting of spiral-like struts. Various physical and biological analyses, including the. morphological structure of spirals, mechanical properties, cell proliferation, and osteogenic activities, were performed to evaluate the effect of the spirals of the scaffold. Osteoblast-like cells (MG63) were used to identify the various in vitro cellular responses on the scaffolds. The spiral-like struts, having unique spiral angles, had a. more significant effect on cell attachment, proliferation, and differentiation compared to normal struts. The results suggest that the scaffold consisting of spiral struts can be a potential biomedical device for various applications in tissue engineering.</P>
Yang, Gi-Hoon,Lee, Hyeongjin,Kim, GeunHyung THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.61 No.-
<P><B>Abstract</B></P> <P>Factors that are important for the development of tissue-engineered scaffolds include an appropriate selection of the physiochemical structure and surface characteristics to achieve the desired cellular responses depending on the target tissue or organ. In this study, we designed the linear polycaprolactone (PCL) strut, a spiral-like PCL strut that was fabricated using a 3D melt-printing system and a modified spiral-like PCL strut via a 3D melt-printing/plasma-etching process. The surface-roughened spiral-like strut showed significantly enhanced wettability and protein absorption abilities, which were closely related to cellular activities compared to those of linear and spiral-like struts. The <I>in vitro</I> cellular activities using the preosteoblasts (MC3T3-E1) indicated that the newly designed surface-modified spiral-like structure showed significantly higher metabolic activities and mineralization compared to those of conventionally 3D-printed struts.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Yang, Gi-Hoon,Kim, Minseong,Kim, GeunHyung Elsevier 2015 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.450 No.-
<P><B>Abstract</B></P> <P>Hybrid biomedical structures have been used widely in various tissue-regenerating materials because they effectively induce exceptional physical and cellular responses. In this study, a new hybrid process was used to design a three-dimensional (3D) biomedical hybrid scaffold with a controlled pore-structure and high mechanical strength. A melt-dispensing method was used to obtain mechanical properties and electrohydrodynamic direct-jet (EHD-DJ) printing was used to provide microsized fibrous structures for the scaffold. Furthermore, the poly(ε-caprolactone) (PCL) hybrid scaffolds were coated biomimetically with type-I collagen to increase bioactive interactions between cells and scaffolds. The fabricated scaffolds showed similar mechanical properties to the two control scaffolds; however, the results of culturing osteoblast-like (MG63) cells showed significant increases in <I>in vitro</I> cellular activities (cell viability>twofold and calcium deposition>sevenfold). Based on these results, we propose a newly designed hybrid scaffold that can support significant <I>in vitro</I> cellular activities at the interface between cells and the 3D micro-pore structure for soft and hard tissue regeneration.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
양경훈(Kyung Hoon Yang),이재범(Jae Bum Lee),김윤기(Yoon Gi Kim),유훈상(Hoon Sang Yoo) 한국경영학회 2000 經營學硏究 Vol.29 No.1
It is important to understand the process of IT diffusion between organizations for meeting effectively IT progress and its changes. The previous studies provide the process of IT diffusion between organizational members, organizational factors facilitating the assimilation of IT within the organization, and the organizational members` usage of communication channels in the IT adoption process. But they failed to provide comprehensively the diffusion process of IT between organizations. Therefore, an empirical research through a field survey has been performed to examine the diffusion process of LAN and RDB with 64 companies to overcome the limits of the previous studies. The purpose of this study is (1) to empirically examine the interaction of companies(prior adopters and potential adopters), (2) to look into the differences of the factors of organizational structure and the periods of IT adoption process between OAE(Organizations Adopting Earlier) and OAL(Organizations Adopting Later), and the importance of communication channels used in IT planning stage and adoption stage, (3) to inquire into the difference between OAE and OAL. The results of this study indicate that there is no interaction between the prior adopters and the potential adopters. Also, there are great significant differences with regards to variables of CEO`s age, CEO`s concern on IT, formalization, centralization, compensation systems, CIO`s attitudes on changes, IT adoption periods, performance of IT. In addition, interpersonal channels have been much more used than mass communication channels in both IT planning stage and adoption stage. This study provides good guidelines to the companies and the vendors in shaping the strategies of IT adoption and IT diffusion respectively.