• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.106-106
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.268-268
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• 2003

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.90-97
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• 2019

Sparkjet actuator, also known as plasma synthetic jet actuator (PSJA), is an active flow control device that has possibility of controling supersonic flow. This actuator utilizes arc plasma to deposit energy onto the gas inside the cavity to raise temperature and pressure. A change in the state of the fluid inside the cavity generates pressure waves and momentum jet, and they are exhausted through out the orifice exit and disturb external flow field. Since the cavity flow is affected by arc plasma, which is an equilibrium plasma and have generated equilibrium flow, the equilibrium state of air should be considered in order to analyze the flow of sparkjet actuator. In this study, numerical program for equilibrium flow was developed for the use of sparkjet actuator analysis. The developed program was validated by comparing the time - accurate jet front positions with the reference result. Then, impulse characteristics of the actuator in the atmospheric quiescent air were explained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.802-805
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• 2004

압전 액츄에이터는 다른 종류의 액츄에이터와 비교할 때 높은 강성, 빠른 응답성의 우수한 특성을 가지고 있다. 벤더형 액츄에이터는 높은 변위의 장점을 가지나 높은 전기장과 기계적 부하인가시에는 내부 응력이 증가하므로서 신뢰성이 감소한다는 단점을 가지고 있다. 이러한 단점을 보완하기 위하여 여러 방법으로 내부 응력을 줄이려는 시도가 있으며 그중 하나는 경사기능 소재나 경사기능 구조를 가지는 액츄에이터의 개발이다. 본 연구에서는 경사기능 특성을 모사한 액츄에이터 구조를 제작하고 그 특성을 조사하였다. 두 가지의 압전상수 d31= - 220 pC/N, d31 =- 100 pC/N를 가지는 세라믹층을 적층하여 벤더형 액츄에이터의 특성을 관찰하였다. 그 결과 두 종류의 세라믹층으로 적층한 액츄에이터가 한가지 특성의 세라믹으로 제작한 액츄에이터 보다 전압인가시 20%이상의 우수한 변위 특성을 나타내었다. 이러한 변화는 내부 응력의 감소에 기인한 것으로 예상된다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.110-110
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• 2004

하나 또는 다수개의 압전액츄에이터(piezoelectric actuator)로 구성된 시스템에서 구동 효율을 높이는데 직접적인 영향을 미치는 고정밀과 빠른 응답 특성을 구현(implementation)하기 위하여, 입력전압에 대하여 출력전압이 선형적으로 추종하고 주파수 가변(variable)이 독립적이며 순차적으로 제어가 가능한 위상가변(phase shifting)형 압전액츄에이터 구동장치의 설계가 필요하다. 구동신호론 증폭하고 가변하는 고전압 증폭 구동장치는 압전액츄에이터 구동에 직접 영향을 주게 되므로, 이의 특성인 고주파에서의 위상지연 보상, 높은 회전비(slew rate)로 고전압에서 정현파의 찌그럼짐을 방지, 전압이득의 가변 및 안정화, 입력 및 출력 임피던스의 개선과 주파스 대역폭(band width)의 확장 등은 매우 중요하다.(중략)

• 연구논문집
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• s.33
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• pp.81-88
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• 2003

A metal jet printing system based on ink jet printing technique is one of the effective equipments for manufacturing elements of display devices, electrical devices, information processing systems, and so on. In order to develop an actuator of the metal jet printing system, bimorph type PZT actuator(length 25.2mm, width 7.2mm, thickness 0.5mm, shim thickness 0.2mm) and its controller(voltage range $\pm24v$, built-in fast recovery diode) were suggested and investigated. Performance tests and characteristic analysis, such as displacement, force, hysteresis and frequency, were carried out. The results show that the suggested actuator and controller are suitable for the metal jet printing system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.570-572
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• 2016

Recent people start to attention about IoT(Internet of Things) and applying IoT on many fields is rising. In this paper we have implemented to control things via web so we used SimpleHTTPServer with Python. Client was used POST, one of web request method which passes through web server and developed a remote control system.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3
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• pp.127-132
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• 2005

Transducers for implantable hearing aids need to be small and to have good performance in frequency responses and vibration properties. From this viewpoint, we Proposed a multi-layer actuator with the piezoelectric single crystal, PMN-PT. for the implantable hearing aid. and verified its adequacy through finite element analyses and experiments. PMN-PT multi-layer actuator samples were fabricated by stacking fourteen layers of the PMN-PT crystal. Each layer were $0.2{\cal}mm$ thick and the actuator sample was $2.8{\cal}mm$ thick in total. We evaluated the performance of the PMN-PT actuator through impedance analyses and vibration displacement measurements, and compared the result with that of a PZT actuator. Results of all the process confirmed the feasibility of the PMN-PT actuator as a good transducer for an implantable hearing aid.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.24-27
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• 2010

This paper presents the design optimization of a linear actuator for fast response of electromagnetic engine valve. The optimization is performed using generic algorithm which is one of global search techniques and not highly dependent on either initial conditions or constraints in the solution domain to maximize the mechanical frequency of the armature mass and valve spring stiffness for fast response of the engine valve. In the results, the mechanical frequency is improved by 30 %.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.201-201
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• 2003