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Ruled Surface로 형성된 임펠러 블레이드의 5-축 가공에 관한 연구
정대일,조현덕,윤문철,최두선,신보성,이응숙 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-
This paper describes the method and the process for impeller machining on 5-axis CNC machining center. Also, The CAD/CAM software for the impeller post processing is developed. The software can be interfaced with Solid-works software for confirmation of the impeller shapes. In this study, blades on impeller is described from Ruled-surfaces between two Ferguson curves. In this study, using 5-axis NC part program obtained from the developed software, a sample impeller was machined on 5-axis CNC machining center. The machined impeller was very agreeable to the designed impeller. Thus, theories proposed in this study can be very useful for the 5-axis machining of impeller blades with Ruled-surfaces.
변연골 흡수가 내측연결 임플란트 매식체의 응력분포에 미치는 영향
윤미정,윤민철,엄태관,허중보,정창모 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.2
Purpose: The change of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. The purpose of this study was to investigate the load transfer of internal conical joint type implant according to marginal bone resorption by using the three-dimensional finite element analysis model. Materials and methods: The internal conical joint type system was selected as an experimental model. Finite element models of bone/implant/prosthesis complex were constructed. A load of 300 N was applied vertically beside 3 mm of implant axis. Results: The pattern of stress distribution according to marginal bone resorption was similar. The maximum equivalent stress of implant was increase according to marginal bone resorption and the largest maximum equivalent stress was shown at model of 1 mm marginal bone resorption. Although marginal bone loss more than 1mm was occurred increasing of stress, the width of the stress increase was decreasing. Conclusion: According to these results, the exposure of thin neck portion of internal conical joint type implant is most important factor in stress increasing. 연구 목적: 지금까지 성공적인 임플란트 치료를 위해 많은 연구가 진행되어 왔으며, 임플란트 주변 골 흡수 현상에 대한 연구는 매우 관심이 높은 분야 중 하나이다. 이에 본 연구에서는 삼차원 유한요소응력분석을 이용하여 변연골 흡수가 내측연결 임플란트 매식체의 기계적 안정성에 미치는 영향을 간접적으로 확인하고자 하였다. 연구 재료 및 방법: 악골에 식립된 내측연결 형태의 임플란트 매식체에 티타늄 소재의 임플란트 지대주를 지대주 나사로 연결하고 상부에 금합금관을 장착하는 삼차원 유한요소모형을 설계하였다. 0, 1, 2, 3 mm의 변연골 흡수 상태를 적용하고, 교합면 중심에서부터 3 mm 편측에 300 N의 수직 하중을 가하여 임플란트 매식체에 발생하는 최대 주응력을 계산하였다. 결과: 유한요소분석결과 변연골 흡수에 따른 임플란트 매식체의 최대 주응력 분포는 유사한 양상을 보였으며, 임플란트 매식체 상단에서 가장 높은 응력 집중이 나타났다. 최대 주응력은 처음 1 mm 변연골 흡수를 가정하였을 때 가장 크게 증가하였고, 이후 변연골 흡수가 증가할수록 응력은 증가하였지만 응력 증가의 폭은 감소하는 경향을 보였다. 결론: 이러한 결과로부터 내측연결 임플란트에서 매식체 두께가 얇은 경부의 노출은 변연골 흡수로 인한 응력 증가에 가장 큰 원인임을 알 수 있었으며, 매식체의 변형, 균열 및 파절 등의 기계적 실패를 감소시키기 위해서는 이에 대한 외과적, 보철적 고려가 필요할 것으로 생각된다.
Ruled Surface로 형성된 임펠러 블레이드 전용 CAD/CAM 시스템 개발 Ⅰ : 모델링에 관한 연구 A Study on the Modeling
조현덕,정대일,윤문철,최두선,신보성,이응숙,董玉革 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.6
We have developed the exclusive CAD/CAM system for the machining of impeller blades. This study is about the modeling method for the effective machining of impeller blades formed by ruled surface. As the impeller is consisted of boss part and blade part, the boss is modeled by rotational surface of hub curve on z-axis and the blade is described by ruled-surfaces between hub curve and shroud curve. This modeling process can be carried out on the software developed in this study. And, the developed software can describe the impeller as a solid model through interface with Solid-Works software. The developed software containing the interface method proposed in this study was very effective for impeller modeling.
Ruled Surface로 형성된 임펠러 블레이드 전용 CAD/CAM 시스템 개발 Ⅱ : 5-축 가공에 관한 연구 A Study on the 5-Axis Machining
조현덕,정대일,윤문철,최두선,신보성,이응숙,董玉革 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.3
This study is continuous with the study 1 (A Study on the Modeling) and the sample impeller of this study is defined by the modeling process of the exclusive CAD/CAM system developed in the study I. And, this study describes a method for the 5-axis machining of impeller blades formed by ruled surface. Therefore, the exclusive CAD/CAM system is the software for modeling and machining of impeller blades. By using the machining method suggested in this study, we could manufacture impeller blades on 5-axis CNC machining center and the machined impeller was very agreeable to the designed impeller. Thus, theories proposed in this study can be very useful for the 5-axis machining of impeller blades.
전덕인,윤보현,정한용,하규섭,신영철,박원명 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.5
Objectives : This study aims to test the validity of the Korean version of Mood Disorder Questionnaire (K-MDQ), a Screening instrument for bipolar disorder. Methods : A total of 238 subjects (126 DSM-IV bipolar outpatients and 112 controls without psychiatric history) completed the K-MDQ. Results : The Cronbach's alpha, used to measure the internal consistency of the scale, was high (0.88). Principal component analysis with varimax rotation revealed three factors, which explained 59.5% of the variance. Individual item correlations with the total score were all statistically significant (p<0.001). The mean total score of the K-MDQ was 8.48 in bipolar disorder and 4.51 in non-clinical participants. A total K-MDQ score of 7 or more excluding further two questions was chosen as the optimal cutoff, as it provided good sensitivity (0.75) and specificity (0.69). Conclusion : The results of this study showed adequate validity of the K-MDQ, suggesting that this instrument is useful for screening of bipolar disorder.
만성정신분열증 환자에서 Cholecystokinin의 치료효과
이창욱,김보연,최중철,백인호 大韓神經精神醫學會 1994 신경정신의학 Vol.33 No.2
This study was designed to investigate antipsychotic properties of cholecystokinin-octapeptide(CCK-8) in schizophrenic patients. Subjects were 30 chronic schizophrenics with residual symptoms following stablization with antipsychotic drugs. CCK-8(0.2㎍/㎏) or placebo was administered intravenously single injection with double-blind method while patients received constant dose of antipsychotic drugs. The clinical effect of CCK-8 was evaluated with BPRS which was applied to patients 2 hours before and 3 and 7 days after drug administration. Results showed no significant differences between CCK-8 group and placebo group.
흰쥐에서 다시마 식이가 메트폴민의 체내동태 및 당 흡수에 미치는 영향
최한곤,장보현,이종달,김정애,유봉규,용철순 한국약제학회 2003 Journal of Pharmaceutical Investigation Vol.33 No.3
Drug interactions with food, on occasion, led to serious nutritional and functional changes in the body as well as alterations of pharmacological effect. It, therefore, should be necessary to take drug interactions with food into consideration for effective and safe therapeutics. Diabetes mellitus is a heterogeneous group of disorders characterized by abnormal glucose homeostasis, resulting in hyperglycemia, and is associated with increased risk of microvascular, macrovascular, and neuropathic complications. However, the precise mechanism of diabetes mellitus remins unclear. Three basic objectives in the care of diabetic patients are maintaining optimal nutrition, avoiding hypo-or hyperglycemia and preventing complications. Laminaria japonica is a brown macroalgae which can be used as a functional diet due to high content of diatery fiber. the purpose of this study was to investigate the effect of Laminaria japonica diet on the pharmacokinetics of metformin which are frequently used in the treatment of diabetes. Diabetic rats induced by strep-tozotocin were employed in this study. Blood concentrations of oral hypoglycemic agent, metformin, were measured by HPLC and resultant pharmacokinetic parameters were calculated by RSTRIP. The mechanisms of drug interaction with food were evaluated on the basis of pharmacokinetic parameters such as k_(a), t_(1/2), C_(max), t_(max), and AUC, C_(max), and k_(a), and increase in t_(max), compared to those with normal diet. This oral glucose test showed that Laminaria japonica diet could lower blood glucose level probably through either inhibiting the activity of disaccharidases, intestinal digestive enzymes, or delaying the absorption of glucose. More studies should be followed to fully understand pharmacokinetic changes of metformin caused by ong-term Laminaria japonica diet.