• Journal of Power Electronics
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• 제19권4호
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• pp.944-955
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• 2019

In this paper, the three-level T-type neutral-point-clamped indirect matrix converter topology and the relative space vector modulation methods are introduced to improve the voltage transfer ratio and output voltage performance. The presented converter topology is based on combinations of cascaded-rectifier and three-level T-type neutral-point-clamp inverter. It can overcome the limitation of voltage transfer ratio of the conventional matrix converter and the high voltage rating of power switches of conventional matrix converter. Two SVPWM strategies for proposed converter are described in this paper to achieve the advantages features such as: sinusoidal input/output currents and three-level output voltage waveforms. Results from Psim 9.0 software simulation are provided to confirm the theoretical analysis. Hence, a laboratory prototype was implemented, and the experimental results are shown to validate the simulation results and to verify the effectiveness of the proposed topology and modulation strategies.

• Journal of Power Electronics
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• 제19권1호
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• pp.99-107
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• 2019

This study proposes a new modulation strategy to deal with unbalanced output voltage that is based on three-level neutral-point-clamped cascaded rectifiers. The fundament idea is to reallocate the value of the voltage levels generated by each of the modules on the basis of space vector pulse width modulation. This proposed modulation strategy can reduce the switching frequency while maintaining the mutual-module voltage balance. First, an analysis of unbalanced output voltage is reflected. Then a new modulation strategy is introduced in detail. Internal module capacitor voltages are balanced by the selection of redundant vectors. Moreover, the voltage balance ability is calculated. Finally, the feasibility of this modulation strategy is verified through experimental results.

• 한국자동차공학회논문집
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• 제3권2호
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• pp.30-41
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• 1995

Gear rattle is a source of vibration and noise in automotive gearbox casing and generally occurs at or near system resonant frequencies. The neutral gear rattle of the gearbox. is affected by the stiffness and hysteresis torque in the clutch disk and drag torque determining balancing point of the clutch disk operating range. The experiment is carried out in the pre-damper type clutch and a manual transmission of a automobile equipped for inline four-sylinder four-cycle 1.5L MPI engine and the computer simulation is executed by 5th order Runge-Kutta method. The results of the simulation analysis and experimental studies show the dynamic behavior of clutch and a phenomenon of the neutral gear rattle with respect to drag torque and torsional characteristics of the clutch.

• 전력전자학회논문지
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• 제24권2호
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• pp.120-126
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• 2019

This study proposes a neutral voltage balance control scheme for stable fault-tolerant operation of an active neutral point clamped (ANPC) inverter using carrier-based pulse width modulation. The proposed scheme maintains the neutral voltage balance by reconfiguring the switching combination and modulating the reference output voltage in order to solve the degradation of the output characteristic in the fault tolerant operation due to the fault of the power semiconductor switch constituting the ANPC inverter. The feasibility of the proposed control scheme is confirmed by HIL experiment using RT-BOX.

• The Korean Journal of Pain
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• 제24권3호
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• pp.141-145
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• 2011

Background: Stellate ganglion block is usually performed at the transverse process of C6, because the vertebral artery is located anterior to the transverse process of C7. The purpose of this study is to estimate the location of the transverse process of C6 using the cricoid cartilage in the performance of stellate ganglion block. Methods: We reviewed cervical lateral neutral-flexion-extension views of 48 patients who visited our pain clinic between January and June of 2010. We drew a horizontal line at the surface of the cricoid cartilage in the neutral and extension views of cervical lateral x-rays. We then measured the change in the shortest distance from this horizontal line to the lowest point of the transverse process of C6 between the neutral and extension views. Results: There was a statistically significant difference in the shortest distance from the horizontal line at the surface of the cricoid cartilage to the lowest point of transverse process of C6 between neutral position and neck extension position in both males and females, and between males and females in both neutral position and neck extension position. The cricoid cartilage level was 4.8 mm lower in males and 14.4 mm higher in females than the lowest point of transverse process of C6 in neck extension position. Conclusions: Practitioners should recognize that the cricoid cartilage has cephalad movement in neck extension. In this way, the cricoid cartilage can be still useful as a landmark for stellate ganglion block.

• East Asian mathematical journal
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• 제30권5호
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• pp.631-637
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• 2014

In this paper, we construct some results on the existence and regularity for solutions of neutral functional differential equations with unbounded principal operators in Hilbert spaces. In order to establish the existence and regularity for solutions of the neutral system by using fractional power of operators and the local Lipschtiz continuity of nonlinear term without using many of the strong restrictions considering in the previous literature.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.689-696
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• 2018

계통 접지(system grounding)는 어떤 이상전압 유입이나 지락 고장 등으로부터 전력 계통의 안정성을 확보할 목적으로 전원의 중성점에 적용하는 것이다. 선박에서 주로 적용되는 계통 접지는 비접지 시스템과 저항 접지 시스템이다. 440V 선박은 비접지 시스템을 적용하고, 3.3kV, 6.6kV, 11kV의 MV(medium voltage) 시스템을 사용하는 선박은 저항 접지 시스템 중에서 주로 고저항접지 방식을 적용한다. 지락 고장은 전기시스템에서 발생하는 모든 고장의 95%정도이고, 지락고장 발생 시 전력 계통의 대지전압이 과도하게 증가하여 선내 절연 시스템에 악영향을 주게 된다. 본 논문에서는 선박에서 적용하는 저항접지 시스템에 대해 지락 고장 발생시 지락 정도에 따라 전력 계통의 대지전압 중성점의 변동 특성을 확인하고자 한다. 이를 위해 우선 접지 시스템의 종류에 따른 특성을 알아보고, 선박의 저항 접지 시스템의 대지전압 중성점에 대한 모델링을 유도한다. 최종적으로 다양한 변수환경에 따라서 대지전압, 선간전압, 중성점 전위 등이 어떻게 변동되는지 MATLAB을 이용한 시뮬레이션을 통해 지락고장 발생시 나타나는 선내 전압의 변화특성을 분석한다.

• 대한치과보철학회지
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• 제28권1호
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• pp.123-135
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• 1990

It would be of importance to determine the neutral Tone by a resultant axis of relation on relation to the mandible in understanding the biomechanics of the mandibular movement. In this study, the neutral zone at the habitual opening and closing mandibular movements is the shape of the paths described by a minimum moving point occured as an average center of the determined instantaneous centers of rotation. Twenty, aged $23{\sim}25$, male dental students without Temporomandibular disorders and with normal occlusion clinically were selected for the study. The habitual opening and closing mandibular movements were recorded by the Gnathorecouder and analyzed by the computer program of a planer rigid body model and the determined method of a minimum moving point. The results obtained from this study were as follows. 1. The minimum moving points were placed in the body of the mandible except two subjects. 2. The mean of maximum displacements of a minimum moving point was $0.62{\pm}0.08cm$ on X-axis and $0.73{\pm}0.16cm$ on y-axis. 3. The mean of maximum displacements of a minimum moving point was $3.39{\pm}0.62cm$ 4. The position and shape of the neutral zone were determined by the position, displacements, and moving distances of a minimum moving point.

• 인지과학
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• 제14권1호
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• pp.11-16
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• 2003

본 논문은 Gabor 웨이브렛 변환을 이용하여 무표정을 포함한 표정영상에서 얼굴의 주요 요소들의 경계선을 추출한 후, FCM 군집화 알고리즘을 적용하여 무표정 영상에서 저차원의 대표적인 특징점을 추출한다. 무표정 영상의 특징점들은 표정영상의 특징점들을 추출하기 위한 템플릿으로 사용되어지며, 표정영상의 특징점 추출은 무표정 영상의 특징점과 동적 연결모형을 이용하여 개략적인 정합과 정밀한 정합 과정의 두단계로 이루어진다. 본 논문에서는 Gabor 웨이브렛과 FCM 군집화 알고리즘을 기반으로 동적 연결모형을 이용하여 표정영상에서 특징점들을 자동으로 추출할 수 있음을 제시한다. 본 연구결과는 자동 특징추출을 이용한 차원모형기반 얼굴 표정인식[1]에서 얼굴표정의 특징점을 자동으로 추출하는 데 적용되었다.

• Journal of applied mathematics & informatics
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• 제27권5_6호
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• pp.1145-1156
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• 2009

In this paper, we consider the existence, uniqueness of the solutions and controllability for the neutral functional integro-differential equations with delay terms by Sadovskii's fixed point theorem.