• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.252-253
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• 2006

This paper presents OC relay coordination to protect distribution system by Adaptive Evolutionary Algorithm(AEA). AEA is a optimization method to overcome the problems of classical optimization. The results show that the proposed method can improve more optimum relay settings than present available methods.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.249-252
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• 2004

• Transactions on Electrical and Electronic Materials
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• v.13 no.5
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• pp.252-255
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• 2012

In order to characterize insulation properties of epoxy/micro-silica/nano-silicate composite (EMNC), long-term and short-term AC treeing tests were carried out undr non-uniform electric field generated between needle-plate electrodes. In a long-term test, a 10 kV (60 Hz) electrical field was applied to the specimen positioned between the electrodes with a distance of 2.7 mm in an insulating oil bath at $30^{\circ}C$, and a typical branch type electrical tree was observed in the neat epoxy resin and breakdown took place at 1,042 min after applying the 10 kVelectrical field. Meanwhile, the spherical tree with the tree length of $237{\mu}m$ was seen in EMNC-65-0.3 at 52,380 min (36.4 day) and then the test was stopped because the tree propagation rate was too low. In the short-term test, an electrial field was applied to a 3.5 mm-thick specimen at an increasing voltage rate of 0.5 kV/s until breakdown in insulating oil bath at $30^{\circ}C$ and $130^{\circ}C$, and the data was estimated by Weibull statistical analysis. The electrical insulation breakdown strength for neat epoxy resin was 1,763 kV/mm at $30^{\circ}C$, while that for EMNC-65-0.3 was 2,604 kV/mm, which was a modified value of 47%. As was expected, the breakdown strength decreased at higher test temperatures.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.252-256
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• 2017

PURPOSE. This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow. MATERIALS AND METHODS. A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (${\alpha}=.05$). RESULTS. The RMS value of lithium disilicate crown was $29.2\;(4.1){\mu}m$ and $17.6\;(5.5){\mu}m$ on the outer and inner surfaces, respectively, whereas these values were $18.6\;(2.0){\mu}m$ and $20.6\;(5.1){\mu}m$ for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface (P<.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas. CONCLUSION. Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns.

• Archives of Plastic Surgery
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• v.45 no.3
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• pp.246-252
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• 2018

Background Slim patients or those with large breasts may be ineligible for breast reconstruction with an abdominal flap, as the volume of the flap may be insufficient. This study aimed to establish that abdominal tissue-based breast reconstruction can be well suited for Korean patients, despite their thin body habitus. Methods A total of 252 patients who underwent postmastectomy breast reconstruction with an abdominal flap from October 2006 to May 2013 were retrospectively reviewed. The patients' age and body mass index were analyzed, and a correlation analysis was performed between the weight of the mastectomy specimen and that of the initial abdominal flap. Results The average weights of the mastectomy specimen and initial abdominal flap were 451.03 g and 644.95 g, respectively. The ratio of the weight of the mastectomy specimen to that of the initial flap was $0.71{\pm}0.23$. There was a strong positive linear relationship between the weight of the mastectomy specimen and that of the initial flap (Pearson correlation coefficient, 0.728). Thirty nulliparous patients had a final-to-initial flap weight ratio of $0.66{\pm}0.11$. The 25 patients who underwent a contralateral procedure had a ratio of $0.96{\pm}0.30$. The adjusted ratio of the final flap weight to the initial flap weight was $0.66{\pm}0.12$. Conclusions Breast weight had a strong positive relationship with abdominal flap weight in Koreans. Abdominal flaps provided sufficient soft tissue for breast reconstruction in most Korean patients, including nulliparous patients. However, when the mastectomy weight is estimated to be >700 g, a contralateral reduction procedure may be considered.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.252-255
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• 2009

This paper proposes a new loss minimization controller (LMC) for induction motor drive. The proposed LMC presents a strategy to minimize the total power losses of induction motor (IM), which is based on simplified equivalent circuit and simplified model of IM. The proposed controller using the field oriented control (FOC) method is to determine an optimal rotor flux for obtaining the minimum total power losses and higher efficiency. Simulation and experimental results are given to validate the effectiveness of the proposed method.

• Bulletin of the Korean Mathematical Society
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• v.43 no.2
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• pp.245-252
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• 2006

In this paper we study the uniform decay estimates of the energy for the nonlinear wave equation of Kirchhoff type $$y'(t)-M({\mid}{\nabla}y(t){\mid}^2){\triangle}y(t)\;+\;{\delta}y'(t)=f(t)$$ with the damping constant ${\delta} > 0$ in a bounded domain ${\Omega}\;{\subset}\;\mathbb{R}^n$.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.251-252
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• 2012

기존의 실습실 관리 프로그램은 불특정 다수를 대상으로 운영되어 바이러스 감염, 개인 정보 유출 등의 문제점으로 인해 관리 및 유지보수가 쉽지 않은 한계점이 있다. 해당 논문에서는 이러한 문제점을 해결하고자 모바일 환경과의 결합을 통해 사용자의 편리성에 기여하고 보안을 강화한 실습실 관리 시스템을 제안하고자 한다.

• Communications of the Korean Mathematical Society
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• v.28 no.3
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• pp.517-526
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• 2013

We give a fixed point theorem for complete fuzzy metric space which generalizes fuzzy Banach contraction theorems established by V. Gregori and A. Spena [Fuzzy Sets and Systems 125 (2002), 245-252] using notion of altering distance, initiated by Khan et al. [Bull. Austral. Math. Soc. 30 (1984), 1-9] in metric spaces.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.249-252
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• 2002

For a precise position control with the resolution of a micrometer, a dual servo system is constructed using a linear motor and a piezoelectric actuator. The switching mode dual servo algorithm is implemented on a DSP board in which A/D and D/A converters are also mounted. It is shown by the experimental results that the precise position control is performed within a few micrometer of position error by using the dual servo system.