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전영환,이동근 원광대학교 치의학연구소 1993 圓光齒醫學 Vol.3 No.2
To repair bony defects with transplanted bone in the body, fresh autogenous bone is undoubtly, the most effective bone graft for clinical applications. But the demineralized bone has the matrix-induced bone formation which was suggested by Urist in 1965. Many authors assisted that demineralized bone powder induces phenotypic conversion of mesenchymal cells into osteoblasts, with high-density bone formation. The process of inducing differentiated cells becomes osteogenic properties. The purpose of this study was to evaluate the osteoinductive capacity of allogenic freeze-dried demineralized bone block (FDD. 7×7㎜) and to compare FDD with the same size of deep-frozen allodeneic bone (DF), fresh autogenous bone (A) after implantation. The histological and ultrastructural features of tissue responses were examined after 1, 2. 4. 6, 8 weeks implantation of each experimental groups in the operative site of the New Zealand white rabbits. The results were as follows : 1. Inflammatory cell infiltration generally has appeared at 1 week, but reduced at 4 weeks in each group, but most severe in DF group. 2. Osteoblastic activity has increased for 4 weeks, but decreased at 6 weeks in each group and there was no significant difference among experimental groups. 3. New bone formation has begun at 1 week, least activations in A groups, and showed the reversal line of bone formation among each group at 6 to 8 weeks. 4. Bone resorption has appeared at 1 week, but disappeared at 4 weeks in both A and DF groups, but more severe in DF than A groups. 5. In ultrastructural changes, the DF group have showed the most remarkable osteoclastic activities among the experimental groups. 6. Osteoid or tangled collagen fibrils near the implanted sites were replaced by more mature, lamellated bony trabeculae during bone remodeling. There was little difference among each experimental groups. 7. During the convertion osteoblasts to osteocyte which embedded within the bone matrix, there was organless-poor cytoplasm, increased nuclear chromatin, abundant rough endothelial reticulum (RER) in each groups. From the above the findings, the DF group showed more bone resorption and foreign body reaction than FDD and A groups, and FDD group showed more new bone formation or osteoblastic activity than DF and A groups in early stage. There was no significant difference of cellular activities among the FDD, DF, and A groups according to the time.
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$H_{\infty}$ 알고리즘을 이용한 Dynamic Voltage Restorer의 제어
전영환,김지원,전진홍,Chun, Yeong-Han,Kim, Ji-Won,Jeon, Jin-Hong 대한전기학회 2001 전기학회논문지 D Vol.50 No.12
Recent trend of increasing automated factories needs supply of high quality power from the utilities. Among the items of the power quality, voltage sag can be compensated by Dynamic Voltage Restorer(DVR). The key feature of the DVR is high response with less transient period to recover from the voltage sag due to the lightning or line-to-ground faults. In this paper we report that $H_{\infty}$ controller is very promising for the practical application to the controller of DVR. Experimental results shown in this paper was obtained by applying the control algorithm to 20 kVA DVR system. The experimental set consists of IGBT-based three phase inverter and the TMS320C32-60 DSP used for main processor of the control board. To simulate the 50% voltage sag, the SCR-based experimental set was constructed.
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전영환 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.2
This paper proposes an algorithm for determining critical generator lists using accelerating power and synchronizing power coefficient (SPC), and critical generator group (CGG) from CGG candidates,which is a combination of critical generators. The accurate determination of CGG provides a more accurate energy margin while providing system operator with information of possible unstable generator group. Classical transient energy function (TEF) method selects the critical generators with big corrected kinetic energy of each generator at the moment of fault removal. However, the generator with small acceleration after fault, that is, the generator with small corrected kinetic energy, is also likely to belong to CGG if the generator has small synchronizing power. The proposed algorithm has been verified to be effective compared with the classical TEF method. We utilized the power system of Korean Electric Power Corporation(KEPCO) as a test system.
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전영환 한국장애인재활협회 2009 재활복지 Vol.13 No.3
본 연구는 장애인근로자에게 제공된 보조공학기기의 미사용에 영향을 미치는 요인을 밝히는 것이다. 분석에 사용된 자료는 2007년 보조공학기기 및 서비스 실태조사이다. 보조공학기기 사용에 영향을 미치는 요인분석은 종속변수가 사용여부인 경우는 로지스틱 회귀분석을 적용했으며 총사용 기간에는 다중회귀분석을 실시하였다. 분석결과 보조공학기기 사용여부에 영향을 미치는 요인으로는 나이, 제조업, 상용제품, 지원된 보조공학기기 수, 비용, 보조공학기기 만족도, 작업수행능력 등으로 나타났다. 보조공학기기 총사용 기간에는 나이, 지체장애, 지원된 보조공학기기 수, 비용, 작업수행능력에서 영향이 있는 것으로 나타났다. 이러한 결과에서 개인적이고 환경적인 특성들 보다 보조공학기기 자체와 보조공학기기 사용에 따른 성과가 보조공학기기 사용에 가장 영향이 있는 것으로 확인되었다. 마지막으로 분석결과에 따른 논의사항을 제시하였다. This study aims to analyze the factors affecting non-use of assistive technology devices which were provided to disabled workers. Data from a 2007 survey on assistive technology devices and services were used. The logistic regression model for non-use, multiple regression model for total time period of use was applied in the study. First, according to the analysis, factors affecting use of assistive technology devices include the following: age, type of industry, type of device (commercial or customized), quantity of devices, cost, device satisfaction, and work performance. This analysis also shows that those factors affecting the total time period of use are age, type of disability, quantity of devices, cost, and work performance. These findings confirmed that the use of assistive technology devices have more influence the device itself and the outcomes of devices rather than personal characteristics or characteristics of employment. In conclusion this study demonstrates several main points of discussion and implications derived from the result of the analysis.
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