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$R-{\theta}$ 좌표계에 의한 원자로 압력용기 차폐해석체계 개발
김하용,구본승,김교윤,이정찬,지성균,Kim, Ha-Yong,Koo, Bon-Seung,Kim, Kyo-Youn,Lee, Chung-Chan,Zee, Sung-Quun 대한방사선방어학회 2005 방사선방어학회지 Vol.30 No.1
A new developing reactor isn't fixed the structure and the materials of reactor components. To perform the shielding analysis for a reactor vessel by $R-\theta$ geometry, it takes much effort and time to modeling of source term according to the change of reactor components every time. Therefore, we developed the shielding analysis system for the reactor vessel by $R-{\theta}$ geometry, which wasn't affected by the reactor core geometry. By using the developed shielding analysis system, we performed the shielding analysis for the reactor vessel of an integral reactor which has the hexagonal geometry of nuclear fuel assemblies in reactor core. We compared the results obtained from the developed system with those obtained from MCNP analysis. Because the results of developed shielding analysis system were more conservative than those of MCNP calculation, it is useful for shielding analysis. As we had developed the new shielding analysis system for a reactor vessel by $R-{\theta}$ geometry, we reduced error of model for reactor core which was formerly designed by hand and saved the time and the effort to design source term model of reactor core. 노심 및 원자로의 구조 및 구성 물질이 확정되어 있지 않은 개발단계의 신형원자로의 압력용기에 대한 $R-{\theta}$좌표에서 차폐해석을 수행하려면, 매번 선원항에 대한 모델작업을 하는데 많은 노력과 시간이 소요된다. 따라서 $R-\theta$좌표에 의한 반경방향의 원자로 압력용기에 대한 차폐해석에 있어서 노심의 기하학적 구조에 영향을 받지 않고 해석할 수 있는 체계를 개발하였다. 개발된 해석체계를 이용하여 육방형 노심배열을 갖는 일체형 원자로의 압력용기에 대한 차폐해석을 수행하여, 그 결과를 MCNP 해석결과와 비교 분석하였다. 분석결과 개발된 해석체계가 좀 더 보수적인 결과를 나타내었으며 이는 차폐해석측면에서 타당하다. 또한 이 해석체계를 개발함으로써 그 동안 수작업으로 작성하였던 노심내부에 대한 모델에 대한 오차를 줄일 수 있으며 이에 소요되는 시간 및 노력을 줄일 수 있을 것으로 판단된다.
김하용(Ha-Yong Kim),이상민(Sang Min Lee),박경훈(Kyung-Hoon Park),최원식(Won-Sik Choy) 대한정형외과학회 2012 대한정형외과학회지 Vol.47 No.5
목적: 소아에서 대퇴골 골절 치료 후 과성장은 흔하게 발생되는 문제이나 치료방법에 따른 과성장의 정도 차이에 대해서는 논란이 있다. 본 연구에서는 유연 골수강내 고정술과 외고정술 사이의 과성장 정도를 비교하고자 하였다. 대상 및 방법: 대퇴골 간부 골절 후 유연 골수강내 고정 또는 외고정기를 이용하여 치료를 받은 2-10세 소아 중 2년 이상 추시가 가능하였던 26예를 대상으로 하였다. 유연 골수강내 고정술로 치료한 환아가 13예, 외고정술로 치료한 환아가 13예였다. 대퇴골의 과성장, 임상결과 및 합병증을 분석하였다. 결과: 유연 골수강내 고정 및 외고정기로 치료 받은 환자 모두에서 유합을 얻었으며 과성장 외의 합병증은 관찰되지 않았다. 유연 골수강내 고정으로 치료받은 환자의 대퇴골 과성장은 평균 4 mm (-6-13 mm)였고 외고정기로 치료 받은 환자는 평균 3 mm (-13-13 mm)였으며 통계적으로 의미 있는 차이는 없었다. 10 mm 이상의 과성장은 유연 골수강내 고정술로 치료하였을 때 3예, 외고정기로 치료하였을 때 1예 발생하였다. 결론: 소아 대퇴골 골절 치료 후 과성장은 유연성 골수강내 고정으로 치료한 경우나 외고정기를 이용하여 치료한 경우 모두에서 발생하는 문제이며 두 방법 사이에 유의한 과성장 정도 차이는 없었다. Purpose: Overgrowth is a common complication after the treatment of pediatric femoral fractures. However, the effect of treatment methods on the overgrowth is controversial. We compared the amount of overgrowth between flexible intramedullary nailing and external fixation. Materials and Methods: Twenty-six children with femoral diaphyseal fractures after a minimum 2 year follow-up were enrolled in this retrospective study. Thirteen patients were treated with flexible intramedullary nailing (FIN) group, and the other 13 patients were treated with external fixation (EF) group. The overgrowth of femur, clinical outcomes, and complications were evaluated. Results: Union was obtained in all patients without major complications, except for overgrowth. Average overgrowth at the 2-year follow-up was 4 mm (?6-13 mm) in the FIN group, and 3 mm (?13-13 mm) in the EF group (p=0.532). Overgrowths of more than 10 mm were observed in four patients; three patients in the FIN group, and one in the EF group. Conclusion: FIN and EF showed similar amounts of overgrowth, after the treatment for pediatric femoral fractures.
반경방향 - 축방향 일체형 4극 전자기 베어링의 설계 (Ⅱ) - 바이어스 자속 공유형 -
김하용(Ha-Yong Kim),김승종(Seung-Jong Kim) 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.12
This paper introduces a new active magnetic bearing(AMB) that can provide both radial and axial control functions in one bearing unit without axial disk. It has a structure of double four-pole AMB or a four-pole AMB where each core is split into two axially. The cores have two kinds of coil winding; they independently generate fluxes on the planes perpendicular or parallel to the shaft. For the radial control action, it works just like a conventional four-pole AMB. Meanwhile, for the axial control, it uses the Lorentz force generated by the interaction of the bias flux for radial control and the axial control flux. In this paper, the proposed structure, principle, and design process based on magnetic flux analysis are introduced, and its feasibility is experimentally verified by using a simple PD control algorithm with a feedforward loop to compensate the coupled flux effect.
김하용(Kim, Ha-Yong),심현식(Sim, Hyun-Sik),이종원(Lee, Chong-Won),강태하(Kang, Tae-Ha) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.3
The active magnetic bearing (AMB) systems mounted in moving vehicles are exposed to the disturbances due to the base motion, often leading to malfunction or damage as well as inaccurate positioning of the systems. Thus, in the controller design of such AMB systems, robustness to base disturbances becomes an essential requirement. In this study, effective control schemes are proposed for the homo-polar AMB system, which uses permanent magnets for generation of bias magnetic flux, when it is subject to base motion, and its control performance is experimentally evaluated. The base motion of AMB system is modeled as the dynamic disturbances in the gravity and base excitation forces. To effectively compensate for the disturbances, the angle feed-forward controller based on the inverse dynamic model and the acceleration feed-forward controller based on the normalized filtered-X LMS algorithm are proposed. The performance test of the prototype AMB system is carried out, when the system is mounted on rate table. The experimental results show that the performance of the proposed controllers for the AMB system is satisfactory in compensating for the disturbances due to the base motion.