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Oscillator with High Harmonic Suppression Using Split Quarterwave Microstrip Resonator
Hoyun Cho,Minho Go,YunHyun Jo,박효달 한국전자통신연구원 2011 ETRI Journal Vol.33 No.1
This letter presents a new type of resonator, namely, the split quarterwave microstrip resonator (SQMR), to improve the poor harmonic suppression and low Q-factors in conventional quarterwave microstrip resonators. An oscillator incorporating the proposed SQMR is designed, fabricated, and tested to demonstrate that, not only the second harmonic suppression, but also the phase noise of the oscillator can be improved. The oscillator with the SQMR shows improved second harmonic suppression of –74.59 dBc and phase noise figure of merit of –169.77 dBc/Hz at 1 MHz offset.
커먼레일 디젤 엔진용 인젝터 드라이버 및 압력 제어기 개발에 관한 연구
노윤현(Yunhyun Roh),양기동(Kidong Yang),조경환(Kyonghwan Cho),최병철(Byungchul Choi) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In recent years, there has been a surge in social demand for safeguarding and conserving the envirornment, and many governments have legislated substantial reductions in diesel engine exhaust emissions. Because of this, various researchers have studied application of high pressure injection to diesel engines in order to reduce emissions. As the result common rail diesel vehicles arc very common on the domestic market.<br/> This paper represents tile injector driver and pressure controller for common rail engine that we developed, manufactured, and simulated, to meet the need common rail researcher required.<br/>
노윤현(Yunhyun Roh),조경환(Kyonghwna Cho) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In recent year, there has been a surge in social demand for safeguarding and conserving the environment, and many governments have legislated substantial reductions in diesel engine exhaust emissions. Because of this, various researchers have studied application of high pressure injection to diesel engines in order to reduce emissions. As the result common rail diesel vehicles are very common on the domestic market. This paper represents the TDA-8000 "Common-Rail Diesel Engine Controller" which TEMS has developed for use common rail diesel engine control sine 2002.
박고은 ( Goeun Park ),정윤현 ( Yunhyun Chung ),조다은 ( Daeun Cho ),김수현 ( Soohyun Kim ),노윤하 ( Yunha Noh ),박정규 ( Junggyu Park ),유견아 ( Kyeonah Yu ) 한국정보처리학회 2023 한국정보처리학회 학술대회논문집 Vol.30 No.2
학교상담은 학생들의 학업 및 심리적 건강을 촉진하는 핵심 구성 요소 중 하나로 자리 잡고 있으며, 코로나 19 로 인한 언택트 시대로의 전환은 비대면 상담 방식의 혁신을 촉발하였다. 본 연구는 AI 챗봇을 활용한 상담 서비스를 통해 학교상담의 효과를 높이고, 학생들의 학업 및 심리적 건강에 대한 지원을 강화하는 데 주력한다. 이러한 연구는 미래의 학교 상담 서비스 분야에 크게 이바지할 것으로 기대된다.
Dynamic Analysis of Rotor Eccentricity in Switched Reluctance Motor with Parallel Winding
Jian Li,Dawoon Choi,Yunhyun Cho 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
This paper presents dynamic characteristics in Switched Reluctance Motor (SRM) with rotor eccentricity and proposes the reduction method of rotor eccentricity effects by the different winding connections. These characteristics investigations are computed by 2D transient magnetic FEM analysis coupled with external circuits. The radial and unbalance magnetic force in the stator, which is the main exciting force of the vibration, is calculated using Maxwell stress method and compared with the performance characteristics according to the serial and parallel connections of windings. The influence of winding method counteracting unbalance forces on the rotor vibration behavior is estimated by the current waveforms of the paralleled paths under rotor eccentricity.
불규칙한 교란을 받는 동적 시스템의 제어에 관한 실험적 연구
이종복(JongBok Lee),조윤현(YunHyun Cho),양인범(InBeom Yang),박성만(SungMan Park),허훈(Hoon Heo) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Experimental study on the control of randomly disturbing system is conducted. External and internal disturbances are imposed to the system in combined manner. A vertical propeller system exposed horizontal weak turbulent air flow is chosen as an experimental model. The aim of the control system is to maintain the angular position of vertical propeller in parallel to air flow. Trajectory Tracking Stochastic Controller (TTSC) is designed to ensure system's stability while following system command. The Trajectory Tracking Stochastic Controller is composed of two controller, one is stochastic controller to suppress internal random noise and the other one is trajectory-tracking controller to follow the command having random noise. The proposed hybrid controller, TTSC, shows remarkable performance in pitch control of vertical propeller system in wind-tunnel test.
엄건우(KunWoo Eom),조윤현(YunHyun Cho),박대명(DaeMyeong Park),최웅철(WoongChul Choi) 한국정보과학회 2010 한국정보과학회 학술발표논문집 Vol.37 No.2B
오늘날 컴퓨터 및 통신기술의 발달과 전자문서의 법적 효용 가치는 많은 기업 및 단체의 전자결재시스템 사용을 가져왔다. 하지만, 전자결재시스템의 보안 취약점은 아직까지 해결되지 않은 심각한 문제이며, 전자결재시스템과 같은 그룹웨어는 내부자 소행에 의한 보안사고가 많이 발생한다. 이에 단순히 기술적인 측면만을 고려해서는 보안 사고를 줄일 수 없다. 본 연구팀은 기술적인 측면뿐만 아니라 물리적, 관리적인 측면까지 고려하여 전자결재시스템의 보안을 향상시키고자 한다. 제안하고자하는 전자결재시스템 보안지침의 주요 내용은 1) 관리적인 보안에서 보안정책, 보안절차, 인원보안을 지키기 위한 고려사항, 2) 물리적인 보안을 위한 고려사항, 3) 기술적인 보안을 위한 고려사항, 앞의 3가지 고려사항을 유기적인 관점에서 바라볼 수 있도록 하고, 이를 통해 향상된 보안성을 바탕으로 더욱 믿을 수 있고, 편리한 전자결재시스템의 활용을 증진시키는 것이다.
이종복(Jongbok Lee),조윤현(Yunhyun Cho),장종수(Jongsoo Chang),허훈(Hoon Heo) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Much of the study on dual controller that guarantee the stability and improvement of the system performance has been carried out. Various irregular noise which may be generated internally in the system is one of the important point to ensure the system performance in designing model tracking controller. The irregular noise in the control system consists of numerical error in operation of digital controller that improve the performance, tracking error and internal noise in system circuit. The stochastic controller used to suppress those irregular internal noise and model tracking controller is used to follow the control law simultaneously. Dual stochastic control design method utilizing F-P-K stochastic control technique developed earlier is proposed to reveal its performance via simulation.