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이동연,조태준,Hye Ran Lee,이강,Hyuk Joo Moon,박문석,유원준,정진엽,최인호 대한정형외과학회 2011 Clinics in Orthopedic Surgery Vol.3 No.3
Background: Fibrous hamartoma is the key pathology of congenital pseudarthrosis of the tibia (CPT), which was shown to havelow osteogenicity and high osteoclastogenicity. This study further investigated the mechanism of impaired osteoblastic differentiationof fi brous hamartoma cells. Methods: Fibroblast-like cells were obtained from enzymatically dissociated fi brous hamartomas of 11 patients with CPT associatedwith neurofi bromatosis type I (NF1). Periosteal cells were also obtained from the distal tibial periosteum of 3 patientswithout CPT or NF1 as control. The mRNA levels of Wnt ligands and their canonical receptors, such as Lrp5 and β-catenin, wereassayed using reverse transcriptase PCR (RT-PCR). Changes in mRNA expression of osteoblast marker genes by rhBMP2 treatmentwere assayed using quantitative real time RT-PCR. Changes in mRNA expression of transcription factors specifi cally involved inosteoblastic differentiation by rhBMP2 treatment was also assayed using quantitative real-time RT-PCR. Results: Wnt1 and Wnt3a mRNA expression was lower in fi brous hamartoma than in tibial periosteal cells, but their canonicalreceptors did not show signifi cant difference. Response of osteoblastic marker gene expression to rhBMP2 treatment showedpatient-to-patient variability. Col1a1 mRNA expression was up-regulated in most fi brous hamartoma tissues, osteocalcin was upregulatedin a small number of patients, and ALP expression was down-regulated in most fi brous hamartoma tissues. Changes inmRNA expression of the transcription factors in response to rhBMP2 also showed factor-to-factor and patient-to-patient variability. Dlx5 was consistently up-regulated by rhBMP2 treatment in all fi brous hamartoma tissues tested. Msx2 expression was downregulatedby rhBMP2 in most cases but by lesser extent than control tissue. Runx2 expression was up-regulated in 8 out of 18fi brous hamartoma tissues tested. Osterix expression was up-regulated in 2 and down-regulated in 3 fi brous hamartoma tissues. Conclusions: Congenital pseudarthrosis of the tibia appears to be caused by fi brous hamartoma originating from aberrant growthof Nf1 haploinsuffi cient periosteal cells, which failed in terminal osteoblastic differentiation and arrested at a certain stage of thisprocess. This pathomechanism of CPT should be targeted in the development of novel therapeutic biologic intervention.
Pseudo-Resonant Effect on a Flexure-Guided Nano-Positioning System
이동연,권대갑 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.3
This study shows that the system performance of a positioning system composed of a PZT (lead zirconate titanate)-driven flexure guide depends largely on the preload applied on the flexure guide and the driving input amplitude. We used a flexure-guided system that had an original resonant frequency of 54 Hz. Our experiment showed that we could increase the driving bandwidth above the original resonant frequency for a case involving a large preload and a small input amplitude. Results showed that there was a specific “separation frequency” where the response of the moving mass of the flexure system decoupled from the response of the PZT and that this specific separation frequency could be selected by a proper choice of the preload and the input amplitude. Near the separation frequency, the pseudo-resonant phenomenon, for example, a large peak and an abrupt phase change between the PZT actuator and the moving body of the flexure guide, occurred. To find the separation frequency, we performed sine sweep tests. To confirm the increased system bandwidth frequency, we performed open-loop sine tracking experiments. Test results showed that the system responded very well up to a frequency 130 Hz, which is higher than the original natural frequency (54 Hz).0
Color detection을 이용한 QR코드 정찰 임무 연구
이동연,문건희,이병윤,유동완,이해인,탁민제 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11
본 논문에서는 Color detection 을 이용하여 QR 코드를 효율적으로 정찰하는 임무를 연구한다. 우선 효과적인 QR 코드 인식을 위해서 카메라를 이용한 영상정보를 획득한다. 영상에는 고고도에서 촬영한 QR 코드와 그 주변 지역에 관련된 정보가 저장된다. 얻어진 영상에 대해 color detection 을 수행하여 QR 코드가 존재 할 수 있는 영역을 선정하고, 선정된 영역에 대한 위치를 계산한다. 또한 각 위치에 존재하는 color 영역의 넓이를 계산해서 이를 기반으로 한 우선순위 선정을 한다. AR.drone 은 계산된 우선순위에 따라 목표와의 거리를 줄이고 주변 지역을 탐색하는 정밀 유도 정찰을 실시한다. 마지막으로, 실험을 통해 관련 이론을 검증하고 개선 사항에 대해서 분석한다. In this paper, The mission for efficient reconnaissance of QR code is studied using color detection. First, the image information is obtained using a camera for an effective QR code recognition. The recorded image is stored in the QR code filmed in the high altitude and information related to the surrounding area. For the obtained image, color detection is performed to select a region in which a QR code may exist, and then the position of the selected region is calculated. In addition, the selection priority is ranked by calculating it based on the width of the color region present in each position. AR.drone reduces the distance to the target based on the calculated priority order to execute a precise guidance reconnaissance to explore the surrounding areas. Finally, the theory is verified by experiments and the future improvements are to be analyzed.