• Advances in nano research
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• v.9 no.3
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• pp.183-191
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• 2020

The content of this study focuses on bending of flexoelectric Magneto-Electro-Elastic (MEE) nanobeams inserted within the foundation of Winkler-Pasternak according to nonlocal elasticity theory. Applying Hamilton's principle, the nonlocal nanobeams' governing equations in the framework higher order refined beam theory are attained and resolved through adapting an analytical solution. A parametric research is demonstrated for studying the effects that magneto-electro-mechanical loadings, the nonlocal parameter, flexoelectric, as well as the aspect ratio all have on the deflection properties of nanobeams. A discovery lead to beam geometrical parameters, the boundary conditions, flexoelectricity and nonlocal parameter partake substantial effects on nanoscale beams' dimensionless deflection.

• Advances in nano research
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• v.8 no.3
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• pp.203-214
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• 2020

This paper investigated bending of magneto-electro-elastic (MEE) nanobeams under hygro-thermal loading embedded in Winkler-Pasternak foundation based on nonlocal elasticity theory. The governing equations of nonlocal nanobeams in the framework parabolic third order beam theory are obtained using Hamilton's principle and solved implementing an analytical solution. A parametric study is presented to examine the effect of the nonlocal parameter, hygro-thermal-loadings, magneto-electro-mechanical loadings and aspect ratio on the deflection characteristics of nanobeams. It is found that boundary conditions, nonlocal parameter and beam geometrical parameters have significant effects on dimensionless deflection of nanoscale beams.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.724-725
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• 2011

현재 전력설비는 디지털 변전소 국제 표준 통신 규격인 IEC61850을 채택하고 있는 추세에 있으며, 온라인 GIS (Gas Insulated Switchgear) 예방진단 시스템의 고객 요구 사양도 IEC61850을 이용하여 외부 인터페이스가 가능한 구조를 포함하고 있다. 본 연구에서는 온라인 GIS 예방진단 시스템에 대한 IEC61850 모델을 제시하고 Logical Node를 구성하였다. 부분방전 데이터를 비롯한 실시간 감시 데이터는 IEC61850의 fixed report 기능으로 구현하였고, 부분방전 이벤트 및 이력 정보는 파일로 저장하여 IEC61850의 file transfer 기능으로 구현하였다. 기능 검증을 위하여 온라인 GIS 예방진단 시스템 서버에 IEC61850 서버 기능을 탑재하였고 상용의 IEC61850 클라이언트 소프트웨어를 이용하여 데이터 통신 및 파일 전송 기능을 확인하였다

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.6
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• pp.647-652
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• 2015

Pull-in voltage model of nano-electro-mechanical system with graphene is investigated for the device optimization. In the pull in voltage model, thickness of graphene layer is assumed to be uniform in vertical and lateral direction. Finite element analysis simulation has verified the feasibility of the suggested model. From the suggested model, pull-in voltage change with graphene thickness and cantilever length can be estimated. Maximum induced stress and graphene thickness have a reciprocal relationship.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.876-879
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• 2003

본 논문은 전동차용 추진제어장치의 재점착제어에 관한 것이다. 본 연구에서는 공전검지 방법에 대하여 기술하고, 등가 관성량을 이용한 추정재점착제어에 관하여 제시한다. 서울시 6호선 국산화 전동차(609편성)와 광주도시철도 1호선 전동차에 적용하여 재점착 제어성의 우수함과 안정성을 검증 하고자 한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.499-500
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• 2007

The existing digital protection relay is continuously growing with an improvement in technology. In this paper, we propose the development of the digital protection relay which displays the trip area in real time. In most of the digital protection relays monitor whether analog signal enters into the pre-determined trip area, but those aren't provide the trip area information for a operator in real time. Therefore, if the digital protection relay continuously displays the trip area in real time, the operator analysis power system status easily. This paper particularly introduces selective ground protective relay and differential protective relay with trip area and presents a method of providing the trip area information to operator in real time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.207-208
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• 2007

Recently, high performance microelectronic devices are designed in multi-layer structure in order to make dense wiring of metal conductors in compact size. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. In this work, we synthesized dielectric composite materials based on epoxy resin, and investigated their thermal stabilities and dynamic mechanical properties for thermal imprint lithography. In order to enhance the mechanical properties and toughness of dielectric material, various modified polyetherimide(PEI) was applied in the resin system. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various conditions were studied using dynamic differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Universal Test Method (INSTRON).

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.104-110
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• 1984

An electro-hydraulic copying system is developed and its performance is experimentally investigated. As compared with a mechanical hydraulic coping system, this system has a basic difference in that; (1) the stylus movement is converted into an electrical signal via a position transducer. (2)the actuator displacement is also measured by a position sensing element, which serves as a feedback signal. Since the system parameters affect the control performance, the response characteristics such as percentage overshoot, rise time, settling time and steady state error are experimentally obtained under variation of these variables. The system parameter include supply pressure, servo amplifier gain and feedback gain. The experimental result shows that the cutting tool follows a stylus input motion to a desirable accuracy. The implication of this result indicates that the developed system can enhance the copying accuracy of the conventionally used mechanical type of hydraulic copying system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.342-347
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• 2003

In this paper, an active vibration control of a translating tensioned string with the use of an electro-hydraulic servo mechanism at the right boundary is investigated. The dynamics of the moving strip is modeled as a string with tension by using Hamilton’s principle for the systems with changing mass. The control objective is to suppress the transverse vibrations of the strip via boundary control. A right boundary control law in the form of current input to the servo valve based upon the Lyapunov’s second method is derived. It is revealed that a time-varying boundary force and a suitable passive damping at the right boundary can successfully suppress the transverse vibrations. The exponential stability of the closed loop system is proved. The effectiveness of the control laws proposed is demonstrated via simulations.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.170-174
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• 2005

A numerical system to extract effective elastic properties of polycrystalline thin-films for MEMS devices is developed. In this system, the statistical model based on lattice system is used for modeling the microstructure evolution simulation and the key kinetics parameters of given micrograph, grain distributions and deposition process can be extracted by inverse method proposed in the system. In this work, effects of kinetics parameters on the extraction of effective elastic properties of polycrystalline thin-films are studied by using statistical method. Effects of the fraction of the potential site($f_p$) among the parameters for deposition process of microstructure on the extraction of effective elastic properties of polycrystalline thin-films are investigated. For this research, polysilicon is applied to this system as the polycrystalline thin-films.