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정성원,박인덕,김재현,이근준,Jeong, Sung-Won,Park, In-Duck,Gim, Jae-Hyeon,Lee, Geun-Joon 한국조명전기설비학회 2007 조명·전기설비학회논문지 Vol.21 No.3
본 논문은 수용가에 대한 전력요금이 각 모선별로 부과될 경우 모선들의 전력품질을 측정하여 이를 비용화할 수 있다고 가정하였다. 이를 계통계획에 반영하여 예상되는 비용은 샘플계통을 통하여 다음과 같은 계산 방법을 제안하였다. 먼저 모선가격을 계산하기 위해서는 계통에서 전력설비의 운전조건은 최적조류계산에 의해 최적화되어 있는 상황으로 가정하여 모선가격[$/MVAH]을 산정하고, 계통의 각 모선에 연결된 부하들의 연중 발생하는 고장에 의해 탈락되는 피해비용을 산출하였다. 결과적으로 제안된 방법은 전력품질을 포함한 모선 총합 비용을 계산시 매우 효과적이였다. This paper measures power quality of bus in case electric charges about customer are imposed by each bus, supposed that can calculate this cost. When reflected this in system planning, expected cost proposed following method through sample system. To calculate nodal cost operating condition of power equipment calculates nodal cost[$/MVAH] supposing by situation that is optimized by OPF(optimal power flow) in system. The damage cost that is shed by fault that happen during year of loads in system that is linked on each bus was produced. As a result, proposed method was very effective in case of calculating bus total cost including power quality cost.
정성원,Seung-Hoon Kang,Min Jeong,Hae-Seong Lim 대한정형외과학회 2016 Clinics in Orthopedic Surgery Vol.8 No.1
Background: Distal humerus intercondylar fractures are intra-articular and comminuted fractures involving soft tissue injury. As distal humerus is triangle-shaped, parallel plating coupled with articular fixation would be suitable for bicolumn restoration in treatment of distal humerus intercondylar fracture. Methods: This study included 38 patients (15 males and 23 females) who underwent olecranon osteotomy, open reduction and internal fixation with the triangle-shaped cannulated screw and parallel locking plates (triangular fixation technique). Functional results were assessed with the visual analog scale (VAS) scores, Mayo elbow performance (MEP) scores and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires. Anteroposterior and lateral elbow radiographs were assessed for reduction, alignment, fracture union, posttraumatic arthrosis, and heterotopic ossification, and computed tomography (CT) scans were used to obtain more accurate measurements of articular discrepancy. Results: All fractures healed primarily with no loss of reduction. The mean VAS, MEP, and DASH scores of the affected elbow were not significantly different from those of the unaffected elbow (p = 0.140, p = 0.090, and p = 0.262, respectively). The mean degree of flexion was significantly lower in the affected elbow than in the unaffected elbow, but was still considered as functional (p = 0.001, > 100° in 33 of 38 patients). Two cases of articular step-offs (> 2 mm) were seen on follow-up CT scans, but not significantly higher in the affected elbow than in the unaffected elbow (p = 0.657). Binary logistic regression analysis revealed that only Association for Osteosynthesis (AO) type C3 fractures correlated with good/excellent functional outcome (p = 0.012). Complications occurred in 12 of the 38 patients, and the overall reoperation rate for complications was 10.5% (4 of 38 patients). Conclusions: Triangular fixation technique for bicolumn restoration was an effective and reliable method in treatment of distal humerus intercondylar fracture. This technique maintained articular congruency and restored both medial and lateral columns, resulting in good elbow function.
Waviness가 있는 볼베어링으로 지지된 회전계의 동특성해석 (I) -진동 해석-
정성원,장건희,Jeong, Seong-Weon,Jang, Gun-Hee 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.12
This research presents an analytical model to investigate vibration due to ball bearing waviness in a rotating system supported by two or more ball bearings, taking account of the centrifugal force and gyroscopic moment of the ball. The waviness of rolling elements is modeled by the sinusoidal function, and it is incorporated into the position vectors of the race curvature center. The Hertzian con tact theory is applied to calculate the elastic deflection and nonlinear contact force while the rotor has translational and angular motions. Both the centrifugal force and gyroscopic moment of the ball and the waviness of the rolling elements are included in the kinematic constraints and force equilibrium equations of a ball to derive the nonlinear governing equations of the rotor, which are solved by using the Runge-Kutta-Fehlberg algorithm to determine the new position of the rotor. The proposed model is validated by the comparison of the results of the prior researchers. This research shows that the centrifugal force and gyroscopic moment of the ball plays the important role in determining the bearing frequencies, i.e. the principal frequencies, their harmonics and the sideband frequencies resulting from the waviness of the rolling elements of ball bearing. It also shows that the bearing vibration frequencies are generated by the waviness interaction not only between the rolling elements of one ball bearing but also between those of two or more ball bearings constrained by the rotor.