• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2292-2297
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• 2010

To improve the performances of Sawyer motors and to regulate yaw rotation, various feedback control methods have been developed. Almost all of these methods require information on the position, velocity or full state of the motor. Therefore, in this paper, a nonlinear observer is designed to estimate the full state of the four forcers in a Sawyer motor. The proposed method estimates the full state using only positional feedback. Generally, Sawyer motors are operated within a yaw magnitude of several degrees; outside of this range, Sawyer motors step out. Therefore, this observer design assumes that the yaw is within ${\pm}90^\b{o}$. The convergence of the estimation error is proven using the Lyapunov method. The proposed observer guarantees that the estimation error globally exponentially converges to zero for all arbitrary initial conditions. Furthermore, since the proposed observer does not require any transformation, it may result in a reduction in the commutation delay. The simulation results show the performance of the proposed observer.

• East Asian mathematical journal
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• v.39 no.3
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• pp.369-376
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• 2023

In this paper, we provide Sawyer type conditions on a pair of weights so that the dyadic paraproduct π_b is bounded from L²(u) into L²(v). The conditions can be obtained by checking the boundedness of the dyadic paraproduct on a collection of test functions.

• 방재와보험
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• s.143
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• pp.8-11
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• 2011

Derrick Sawyer는 26년간 소방관으로 재직하면서 대민화재안전교육 업무를 총괄하고 있다. NFPA의 대도시 화재안전 TF에 참여하는 등 활발한 활동을 하고 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.696-699
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• 2003

In this study, we suggested the model to precisely evaluate the ferroelectric hysteresis loop, using the modified Sawyer-Tower circuit and the ferroelectric capacitor with a MDFM(Metal-Dielectric-ferroelectric-Metal) structure. The mathematical expression of dipole polarization is applied to the numerical integration algorithm, and the fatigue property can be considered including the dielectric layer between ferroelectrics and bottom electrode. The validity of our model is proved comparing the estimated value of our model and the measured results of PLT(10) thin film.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.65-91
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• 2001

Errors and its compensation in the measurement of dielectric hysteresis in ferroelectric by using Sawyer-Tower circuit were discussed. When ferroelectrics are lossy, remanent polarization and coercive field are likely to be over-estimated. As the DC conductivity and measuring time increases, measurement errors in ferroelectric properties increase. Current hysteresis measurement was suggested for compensation such errors.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.219-226
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• 2005

When a ferroelectric film has an inhomogeneous distribution of charged defects, a voltage shift in the polarization curve is induced by the internal field generated in the film. The direction and the magnitude of voltage shift in the P-V hysteresis curves obtained by the Sawyer-Tower method are different from those obtained by the virtual ground method. In this study, the asymmetric behavior in the P-V hysteresis curves of inhomogeneous ferroelectric films was investigated with a physical model and the polarization curves obtained by the Sawyer-Tower and the virtual ground methods are compared.

• Mycobiology
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• v.41 no.1
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• pp.59-62
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• 2013

Japanese pine sawyer beetle (Monochamus alternatus) is an economically important pest in coniferous trees. Ophiostoma ips was isolated from the beetle and identified based on analysis of morphological properties and the ${\beta}$-tubulin gene sequence. The fungus easily produced perithecia with a long neck on malt extract agar and its ascospores were rectangular shaped. This is first report of Ophiostoma species associated with the pinewood nematode vector beetle in Korea.

• Journal of the Korean Ceramic Society
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• v.38 no.7
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• pp.667-671
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• 2001

Sawyer-tower 회로를 이용한 강유전 이력곡선의 측정과정에서의 주요 오차 원인을 살펴보고 이에 대한 대안을 제시해 보았다. 강유전체 시편에 존재하는 직류 누설성분에 의해 잔류분극과 항전계는 과대평가될 수 있는 위험성이 항상 있음을 알 수 있었으며 이러한 오차의 보정에 대하여 논의하였다. 또한 강유전 이력곡선의 측정에서 측정하는 시간이 증가되면서 시편의 발열로 인해서 시편의 온도가 증가하게 되어 잔류분극 값과 항전계 값이 감소하는 경향으로 나타남을 관찰하였고, 그 대책을 제안하였다.

• Journal of architectural history
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• v.26 no.4
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• pp.19-34
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• 2017

The purpose of this study was to comprehend the assignment and the procurement method of wood works' craftsman through the Salleung-dogamuigwes in royal tombs constructions in the late Joseon period. Following conclusions have been reached through the study. First, Carpenter and other nine craftsmen were introduced in carpentry works. The craftsmen were put in by occupation to maintain the quality of the government building construction by wood processing area. It was distinguished by frame member, Sujangjae, window framing wood, decorative member. Second, sawyer showed a sharp increase in the latter half of the 18th century and declined since the middle of the 19th century. This is closely related to the increase in demand for building materials and the growth of civilian wood products. As a maximum of 300 people have been assigned to the craftsmen in the woodwork, it can be seen that the work has been divided by the process. Third, the national carpenter was difficult to procure from the 17th century to the beginning of the 18th century. From the middle 18th century, the system procuring national carpenter was stabilized. In the 19th century, the input ratio of the national craftsmen seems to have decreased significantly and seems to have kept it at the minimum level. Forth, sawyer were procured through Seongonggam from the late 18th century through the mid 19th century. That means that the role of the sawyer had become important. Since Jogakjang is not a necessary manpower, it usually has civilian artisans.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.340-343
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• 1992

Fundamental positioning characteristics of a dual-axis Sawyer linear motor are described. The Sawyer motor is capable of high positional accuracy. An electronic control unit of the motor whose velocity is proportional to the frequency of the electric current was produced in our laboratory. The positioning system was constructed using two Sawyer motors, an air bearings suspension unit and an electronic control unit. The stable motion of the motor was confirmed on the open loop operation. The adjustable operating conditions were the live load of 1 kg, the maximum acceleration of 1.2G and the maximum velocity of 350 mm/s. Absolute positioning accuracy was improved within .+-.5.mu.m, on microstep operating conditions of dividing one pitch of 508.mu.m into 508 steps. The following two conclusions were obtained. An accelerating-cruising-decelerating control is effective for reduction in the travel time required. Also, microstep operation is effective for improving the resolution of position.