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Jin‑Kyung Jeon,Hyunseon Seo,Jimin Park,Soo Ji Son,Yeong Rim Kim,Eun Shil Kim,Jong Woong Park,Woong‑Gyo Jung,Hojeong Jeon,Yu‑Chan Kim,Hyun‑Kwang Seok,Jae Ho Shin,Myoung‑Ryul Ok 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4
The excessive initial corrosion rate of Mg is a critical limitation in the clinical application of biodegradable Mg implantsbecause the device loses its fi xation strength before the fractured bone heals. This study suggests a new approach to overcomethis hurdle by accelerating tissue regeneration instead of delaying the implant biodegradation. As angiogenesis is anessential process in early bone regeneration, a Mg implant coated with electrospun nanofi bers containing nitric oxide (NO),which physiologically promotes angiogenesis, is designed. The integrated device enables adjustable amounts of NO to bestored on the NO donor-conjugated nanofi ber coating, stably delivered, and released to the fractured bone tissue near theimplanted sites. An in vitro corrosion test reveals no adverse eff ect of the released NO on the corrosion behavior of the Mgimplant. Simultaneously, the optimal concentration level of NO released from the implant signifi cantly enhances tube networkformation of human umbilical vein endothelial cells without any cytotoxicity problem. This indicates that angiogenesis canbe accelerated by combining NO-releasing nanofi bers with a Mg implant. With its proven feasibility, the proposed approachcould be a novel solution for the initial stability problem of biodegradable Mg implants, leading to successful bone fi xation.
FDM에서 Build Orientation이 쾌속조형물의 표면에 미치는 영향
전재억,서진호,권광진,권혁준,정진서,하만경 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-
Fused deposition (FD) modeling by Stratasys Inc., is one of the material deposition subfamilies of solid freeform fabrication (SFF) technologies. In this process, build material in the form of a flexible filament, is heated to a semi-liquid state and extruded from a controlled deposition head onto a fixtureless table in a temperature controlled environment. The position of nozzle is computer controlled relative to the base, which allows geometric complex models to be made to precise dimensions. FDM provide what the part was directly tested by the worker. It provide believable data. This Study is identify to surface roughness by build orientation adjustment. So, the paper is the study on surface roughness by build orientation at FDM.
이동 애드 혹 네트워크에서의 환경적응형 QoS AODV 라우팅 프로토콜에 관한 연구
裵振勝,宋東勳,吳世德,鄭燦赫,金玄郁,李光培,文泰洙,郭承郁,河載承 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-
In this paper, we propose a bidirectional mobile Ad Hoc routing protocol based on AODV(ad-hoc on-demand distance vector routing) with QoS(quality of service) support. At presence, wireless mobile communication focuses on how to efficiently support mobility of users more than QoS guarantee. However, in order to satisfy requirement of various applications which have been or will be served, QoS guarantee between end points is a very important issue. The existing AODV routing protocol is implemented to use only BE (Best Effort) service. However, actual wireless mobile environment requires to reduce a waste of communication resources and meet with the real-time change of data paths by setting up routes with QoS support, considering available communication resources at each node in advance. Therefore, in this thesis, we propose an adaptive QoS support method using hello message in order to rapidly meet with the change of available communication resources and to smoothly perform route maintenance. For performance evaluation, we analyzed the average data reception rate. At that time, we used evaluation parameters such as node's mobility-stop time, hello message period, and packet priority, considering the node's mobility and the number of best effort/QoS data flows. As results, we found that with our proposed method the average data reception rate was increased 16.293%, 15.914%, 17.238% for 300 mobility-stop second case and 4.809%, 4.264%, 2.956% for 300 mobility-stop second case.
FDM에서 경사면의 표면과 면적오차법의 관계에 대한 연구
전재억,정진서,황영모,김수광,김준안,계중읍,하만경 한국공작기계학회 2002 한국공작기계학회 추계학술대회논문집 Vol.2002 No.-
In any rapid prototyping process, the layer by layer building process introduces an area error between the staircase and the surface line specified by the computer-aided design model. This affects the dimensional accuracy as well as the surface finish for different part build orientations. This paper describes a methodology for computing the area error for any orientation of the part built by the fused deposition modelling system. This technique can be applied to determine the best build orientation of the part, based on the minimum area error. This technique is verified by comparing the results with the experimental measurements of the area error of the parts built at different orientations.
최광진,장일영,권종주,송재호 金烏工科大學校 1994 論文集 Vol.15 No.-
The object of this study is to present an analytical method using superposition of displacement due to flexural crack and diagonal tension crack in reinforced concrete members. Flexural displacement caused by bending moment could be found by the double integration of curvature derived from the relationship between moment and curvature. The macro model of shear deformation from the viewpoint of diagonal tension crack occurrence and its development has been developed. The rotational angle due to diagonal tension crack could be evaluated by using strain compatibility, force equilibrium and moment equilibrium. Furthermore the bonding characteristics between concrete and steel as well as the characteristics of dowell have been taken into consideration. The theoretical values calculated using the analytical method developed in this study have been investigated in comparison with the experimental ones which were carried out earlier in order to prove it s validity. From the results it has been shown that theoretical values agree quite well with experimental ones, and it could be pointed out that presented analytical method is widely acceptable for the practical analysis of flexural displacement of reinforced concrete members.
안면부 기저상피세포암의 인접표피에서 p53 발현 양상에 관한 연구
김광진,김대중,김재훈 순천향의학연구소 1999 Journal of Soonchunhyang Medical Science Vol.5 No.1
The tumor suppressor gene, p53, has proved to be one of the genes most often modified in human cancers. These aterations consist mainly of point mutations located in the evolutionarily conserved sequences which render the protein inactive for its normal biologic functions. Many mutations of p53 result in a protein product that is abnormally stable, so it becomes readily detectable by immunochemistry. Immunohistochemical overexpression of p53 has been observed not only invasive tumors but also in precancerous or early lesions of tumors of the skin. Overexpression of p53 might be useful marker to identify precursor lesions of cancers arising de novo, which are histopathologically indistinguishable from normal cell. We were studied the p53 expressions immunohistochemically to identify a precursor lesion of basal cell carcinoma in the epidermis adjacent to basal cell carcinoma. With anti-p53 antibodies of DO7, p53 expression was frequently detected in the epidermis adjacent to basal cell carcinomas arising on the face and in the normal epidermis with usual sun exposure. In the epidermis adjacent to basal cell carcinoma, stained cells were occasionally clustered in a small area, but no cluster was found in the normal epidermis with usual sun exposure. The expression was less frequent in the normal epidermis with rare sun exposure. We have carried our PCR-sequencing of exon 5-8 of the p53 gene in 7 basal cell carcinoma and two normal epidermis with immunohistochemically positive and cluster formed. Heterozygous mutations were detected in 4 of 7 (57%) samples investigated. All mutations were G:C-A:T transitions, three at codon 248 and one at codon 273. But no mutation was detected in two normal epidermis with cluster formed positive staining. We conclude that 1. Because all basal cell carcinoma specimens examined here were obtained from facial lesions that were usually exposed to sunlight, the frequent p53 overexpression-detected in the epidermis adjacent to basal cell carcinoma might be related to chronic UV light exposure. 2. The accumulation of p53 was also frequently detected in the epidermis adjacent to basal cell carcinoma developing on the face that was usually sun-exposed. In the epidermis adjacent to basal cell carcinoma, unlike normal epidermis with usual sun exposure that was scattered pattern, the stained cells were occasionally clustered in small areas of the epidermis. 3. A missense mutation was not found in the epidermis adjacent to basal cell carcinoma. 4. The correlation between immunohistochemicl overexpression or pattern and underlying mutation is not absolute, but there might be useful as excisional marker because the p53 staining positive cells ,that was clustered pattern, were possible result for clonal expansion of p53 mutant cells.