• 한국전산구조공학회논문집
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• 제15권4호
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• pp.703-713
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• 2002

최근에 불연속 근사변위함수와 보조받침을 이용한 특이기저함수를 도입하여 균열의 불연속성과 특이성을 구현한 개선된 EFG(Element-Free Galerkin) 균열해석기법이 제안되었다. 개선된 EFG 균열해석기법은 균열의 성장에 따른 해석모형의 수정 없이도 높은 정확도로 균열전파해석을 수행할 수 있지만, 다른 무요소법과 마찬가지로 해석결과가 사용되는 해석계수에 의존하게 된다. 본 연구에서는 개선된 EFG 균열해석기법에서 사용하는 해석계수 즉, compact 받침 크기, 팽창계수, 선단주변에서의 형상함수의 평활화, 보조받침을 사용하는 절점개수가 수치해석 결과에 미치는 영향을 분석하였다. 균열문제에 대한 patch 시험을 통해 응력에 대한 L₂오차노름과 응력확대계수를 산정하여 해석계수의 영향을 분석하였으며, 그 결과는 해석계수의 선택에 대한 지침으로 제시된다.

• 한국전자통신학회논문지
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• 제8권11호
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• pp.1675-1680
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• 2013

최근 저소음, 고속, 고추력의 반송장치가 요구됨에 따라 영구자석 선형동기전동기가 대두되고 있으나 반송경로 전장에 전기자를 설치하는 선형 동기전동기의 특성으로 인해 장거리 반송장치에 적용시 설치비용의 증가를 가져온다. 따라서 우리는 전기자를 분산시켜 배치하는 방법을 제안하여 비용증가의 문제점을 해결하고자 하였다. 하지만 가동자의 진행시 분산배치된 전기자 사이를 통과하게 되면 전기자의 불연속 구간인 단부에 의해 디텐트력이 발생하여 추력 맥동이 발생하고 기기 성능저하와 소음, 진동의 원인이 된다. 따라서 본 논문에서는 단부에 의한 영향을 저감하기 위해 전기자 끝단의 치 높이와 보조치 형상에 따른 디텐트력의 특성을 파악하고 다구찌의 실험계획법을 이용하여 단부 효과를 가장 저감할 수 있는 형상을 제안하였다.

• Journal of Power Electronics
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• 제16권1호
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• pp.362-373
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• 2016

The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u_Ee) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.

• 한국컴퓨터정보학회논문지
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• 제28권11호
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• pp.43-52
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• 2023

고무생산업체에서 생산된 고무는 레오미터 측정을 통해 품질 적합성 검사가 이루어진 후, 자동차 부품을 위한 2차 가공으로 이어진다. 그러나 레오미터 검사는 인간에 의해 진행되고 있으며, 숙련된 작업자에게 매우 의존적이라는 단점이 존재한다. 이러한 문제점을 해결하기 위해 본 논문에서는 딥러닝 기반 레오미터 품질 검사 시스템을 제안한다. 제안된 시스템은 레오미터의 시간적, 공간적 특성을 활용하기 위해 LSTM과 CNN을 조합하였고, 각 고무의 배합재료를 보조(Auxiliary) 데이터 입력으로 사용해 하나의 모델에서 다양한 고무 제품의 품질 적합성 검사가 가능하도록 구현하였다. 제안된 기법은 30,000개의 데이터셋으로 그 성능을 학습 및 검사하였으며, 평균 f1-점수를 0.9942 달성하여 그 우수성을 증명하였다.

• 대한수학회보
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• 제30권2호
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• pp.229-238
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• 1993

Let M be an n-dimensional compact Riemannian manifold with boundary .part.M. We consider the Neumann eigenvalue problem on M of the equation (Fig.) where .upsilon. is the unit outward normal vector to the boundary .part.M. due to the importance of Poincare inequality for analysis on manifolds, one wishes to obtain the lower bound of the first non-zero eigenvalue .eta.$_{1}$ of (1.1). For the purpose of applications, it is important to relax the dependency of the lower bound on the geometric quantities. For general compact manifolds with convex boundary, Li-Yau [3] obtained the lower bound of .eta.$_{1}$. Recently, Roger Chen [1] investigated the lower bound of the first Neumann eigenvalue .eta.$_{1}$ on compact manifold M with nonconvex boundary. We investigate the lower bound .eta.$_{1}$ with the same conditions as those of Roger chen. But, using the different auxiliary function, we have the following theorem.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3007-3018
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• 2011

This paper describes how to apply to commutate of thyristor efficiently. Thyristor is used for the high power system, as the research to secure domestic technology of the Current Source Inverter(CSI) for the synchronous motor operation which is used for the propulsion system of KTX. It has been composed to be available for the stable switching operation of the thyristor by supplementing problem of load commutation method, according to small Counter ElectricMotive Force(EMF) at low speed area of synchronous motor, via auxiliary commutation circuit using forced commutation method. We also have verified through the simulation using the Matlab.

• 치위생과학회지
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• 제11권3호
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• pp.135-154
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• 2011

Dental hygiene was originated from dentistry and dental hygiene knowledge was a component of dental knowledge body. Since the late 1980s dental hygiene theory was began to develop. Nursing theories such as metaparadigm, nursing process and human need theory affected theory development as dental hygiene process. Dental hygiene process provides a framework for high quality dental hygiene care. Dental hygiene process include five phases; assessment, dental hygiene diagnosis, dental hygiene planning, implementation, evaluation. Dental hygiene process of care is recognized as standard for dental hygiene education and clinical dental hygiene practice. Dental hygiene practice has moved from auxiliary model to professional model. Critical thinking skill and disposition are necessary to provide evidence-based dental hygiene care using dental hygiene process as clinical process and critical thinking process. Critical thinking, problem solving and evidence-based practice must be integrated into dental hygiene process for quality dental hygiene care.

• 충청수학회지
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• 제31권3호
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• pp.287-308
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• 2018

This paper deals with blow-up phenomena for an initial boundary value problem of a quasilinear parabolic equation with time-dependent coefficient in a bounded star-shaped region under nonlinear boundary flux. Using the auxiliary function method and differential inequality technique, we establish some conditions on time-dependent coefficient and nonlinear functions for which the solution u(x, t) exists globally or blows up at some finite time $t^*$. Moreover, some upper and lower bounds for $t^*$ are derived in higher dimensional spaces. Some examples are presented to illustrate applications of our results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.385-387
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• 1996

A novel two stage soft-switching ac-to-dc convener with power factor correction is proposed. The proposed convener provides zero-voltage-switching (ZVS) condition to main switch of boost pre-regulator without auxiliary switch. Comparing to the conventional two stage approach(ZVS-PWM boost rectifier followed by off-line ZVS dc-dc step down converter), the proposed approach is simple and reducing EMI noise problem. A new simple DC-linked energy feedback circuit provides zero-voltage-switching condition to boost pre-regulator without imposing additional voltage and current stresses and loss of PWM capability. Operational principle, analysis, control of the proposed converter together with the simulation results of 1KW prototype are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.386-392
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• 1997

Recently, according to developing industry and life style, power consumption have been increased year after year. Currently these much power demand from power consumer is weakening the allowable power reserve margin in summer. As one of the remedies about this problem, the small scale utility interactive photovoltaic system(UIPVS) is considered for auxiliary power source. For this system one of problems to be solved technically, system operating power factor. Generally in case of small scale system, system is operated in unity power factor. But this unity power factor operating mode decrease power factor viewed from utility because UIPVS supply active power to utility. Therefore this paper propose UIPVS with power factor correcting function and this system is analyzed.