• 한국정보통신학회논문지
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• 제3권2호
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• pp.291-304
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• 1999

주 연구에서는 압전체에서의 IDT 변환기, 음향 반사기에 대한 전기 음향 모드의 결합 모드 방정식을 유도, 정리함으로써 SAW 공진기 필터의 결합 모드를 수학적으로 분석할 수 있는 모델링 방법을 소프트웨어 설계 모듈화하고, SAW 공진기 필터를 구성하고 있는 각 구성 요소에 대한 회로적인 결합 방법의 제안을 통하여 SAW 결합 모드 공진기 필터의 설계 및 시뮬레이션 방법을 제안하였다. 또한, 제작된 소프트웨어 설계 모듈을 시뮬레이션 소프트웨어 패키지화함으로써 설계자가 손쉽게 이동통신기기용 결합 모드 공진기 필터를 설계할 수 있도록 그래픽 사용자 인터페이스를 갖는 SAW 결합 모드 공진기 필터의 설계 시뮬레이터를 구현하였으며 이를 통하여 이동통신기기에서 사용할 수 있는 결합 모드 공진기 필터를 모의 설계하고 주파수 특성을 해석함으로써 그 응용 타당성을 제시하였다.

• Structural Engineering and Mechanics
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• 제56권6호
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• pp.1021-1040
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• 2015

An effective method to calculate aerodynamic loads and aeroelastic responses of large wind turbine tower-blade coupled structures in yaw condition is proposed. By a case study on a 5 MW large wind turbine, the finite element model of the wind turbine tower-blade coupled structure is established to obtain the modal information. The harmonic superposition method and modified blade-element momentum theory are used to calculate aerodynamic loads in yaw condition, in which the wind shear, tower shadow, tower-blade modal and aerodynamic interactions, and rotational effects are fully taken into account. The mode superposition method is used to calculate kinetic equation of wind turbine tower-blade coupled structure in time domain. The induced velocity and dynamic loads are updated through iterative loop, and the aeroelastic responses of large wind turbine tower-blade coupled system are then obtained. For completeness, the yaw effect and aeroelastic effect on aerodynamic loads and wind-induced responses are discussed in detail based on the calculating results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.125-128
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• 2008

30톤급 액체산소-케로신 액체로켓엔진 개발의 중간 단계로서 연소기를 제외한 터보펌프 등의 엔진 주요 구성품을 이용한 터보펌프+가스발생기 개회로 연계시험이 수행되었다. 터보펌프+가스발생기 개회로 연계시험의 시험기 구성 및 시험결과를 제시하였다. 연소기를 오리피스로 모사하는 상태에서의 터보펌프+가스발생기 개회로 연계시험기의 예냉, 시동기를 이용한 시동 및 가스발생기 점화, 터보펌프 정격 구동이 성공적으로 수행되었다. 개회로 연계시험 결과는 터보펌프+가스발생기 폐회로 연계시험 수행을 위해 활용되었다.

• Wind and Structures
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• 제32권3호
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• pp.267-281
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• 2021

Bending-twisting coupling induced in big composite wind turbine blades is one of the passive control mechanisms which is exploited to mitigate loads incurred due to deformation of the blades. In the present study, flutter characteristics of bend-twist coupled blades, designed for load alleviation in wind turbine systems, are investigated by time-domain analysis. For this purpose, a baseline full GFRP blade, a bend-twist coupled full GFRP blade, and a hybrid GFRP and CFRP bend-twist coupled blade is designed for load reduction purpose for a 5 MW wind turbine model that is set up in the wind turbine multi-body dynamic code PHATAS. For the study of flutter characteristics of the blades, an over-speed analysis of the wind turbine system is performed without using any blade control and applying slowly increasing wind velocity. A detailed procedure of obtaining the flutter wind and rotational speeds from the time responses of the rotational speed of the rotor, flapwise and torsional deformation of the blade tip, and angle of attack and lift coefficient of the tip section of the blade is explained. Results show that flutter wind and rotational speeds of bend-twist coupled blades are lower than the flutter wind and rotational speeds of the baseline blade mainly due to the kinematic coupling between the bending and torsional deformation in bend-twist coupled blades.

• Applied Science and Convergence Technology
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• 제24권4호
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• pp.102-110
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• 2015

Fluid model based numerical analysis is done to simulate a plasma processing system with electrodes at floating potential. $V_f$ is a function of electron temperature, electron mass and ion mass. Commercial plasma fluid simulation softwares do not provide options for floating electrode boundary value condition. We developed a user subroutine in CFD-ACE+ and compared four different cases: grounded, dielectric, zero normal electric field and floating electric potential for a 2D-CCP (capacitively coupled plasma) with a ring electrode.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.773-785
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• 2012

In this paper, we establish sufficient conditions for the existence and uniqueness of solutions to a general class of three-point boundary value problems for a coupled system of nonlinear fractional differential equations. The differential operator is taken in the Caputo fractional derivatives. By using Green's function, we transform the derivative systems into equivalent integral systems. The existence is based on Schauder fixed point theorem and contraction mapping principle. Finally, some examples are given to show the applicability of our results.

• 한국미생물·생명공학회지
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• 제21권5호
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• pp.461-467
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• 1993

Transglycosylation reaction of cyclodextrin glucanotransferase (CGTase) was analyzed in the attrition coupled heterogeneous reaction system using raw starch as a donor` and mono-, di-saccharide, and glycoside as acceptors. For transglycosylation reaction of stevioside, the transglycosylation rate was similar and the transglycosylation yield was increased compare with conventional process using liquefied starch as the donor. Also the accumulation of maltooligosaccharides in reaction mixture was minimized.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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• pp.187-190
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• 2000

Chua's circuit is a simple electronic network which exhibits a variety of bifurcation and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. In this paper, a transmitter and a receiver using two identical Chua's circuits are proposed and synchronizations of a power line are investigated. Since the synchronization of the power line system is impossible by coupled synchronization, theory having both the drive-response and the coupled synchronization is proposed. As a result, the chaos synchronization has delay characteristics in the power line transmission system caused by the line parameters L and C.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2404-2406
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• 2000

Chua's circuit is a simple electronic network which exhibits a variety of bifurcation and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. In this paper, a transmitter and a receiver using two identical Chua's circuits are proposed and synchronizations of a T or ${\pi}$ type power line are investigated. Since the synchronization of the power line system is impossible by coupled synchronization, theory having both the drive-response and the coupled synchronization is proposed. As a result, the chaos synchronization has delay characteristics in the power line transmission system caused by the line parameters L and C

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.654-659
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• 2009

최근 웹을 기반으로 하는 소프트웨어가 발전하면서, 웹을 통한 서비스가 점차 증가하고 있다. 이것 때문에 많은 연구기관과 보고서들이 웹을 소프트웨어의 플랫폼이라고 부르고 있다. 이렇게 웹 기술이 발전하는 동안 Wireless Sensor Network(WSN)의 미들웨어와 응용 서비스는 데스크탑의 운영체제 기반에서 개발되었다. 그래서 WSN의 기술은 데스크탑 어플리케이션의 한계점을 가지고 있다. 그리고 센서 노드의 하드웨어와 밀접한 관련이 있는 강 결합(Tightly-Coupled) 구조 때문에 WSN의 통합, 응용 서비스 배포, 유지보수 관리 등에 어려움이 있다. 이와 다르게 Web 은 약 결합(Loosely-Coupled)이고 개방된 시스템이기 때문에 Web Service 나 Rich Internet Application(RIA)는 이러한 한계점을 해결할 수 있도록 도와준다. 특히 RIA는 웹 어플리케이션이지만 데스크탑 어플리케이션과 비슷한 사용자환경과 다양한 통신방법을 제공하기 때문에 WSN 응용서비스의 플랫폼이 될 수 있다. 본 연구에서 WSN의 연결성과 접근성을 인터넷으로 확장시키고 RIA를 적용하여 실시간 메시지 시스템을 제안한다.