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이훈기,최규훈 대한전자공학회 2006 電子工學會論文誌 IE (Industry electronics) Vol.43 No.3
This paper described an 8bit, 100Msample/s CMOS D/A converter using a glitch-time minimization technique for the high-speed sampling rate of 100MHz level. The proposed DAC was implemented in 0,35 μm Hynix CMOS technology and adopts a current mode architecture to optimize sampling rate, resolution, chip area. The DAC linear characteristics was similar to the proposed specification and the prototype error between DNL and INL is less than 0.09LSB respectively. Also, the manufactured DAC chip was analyzed the cause of error operation and proposed the field considerations for chip test. 이 논문은 100MHz 수준의 고속 신호 샘플링을 위해 글리치 최소화 기법을 적용한 8비트 100MHz CMOS D/A 변환기 (Digital to Analog Converter : DAC) 회로를 제안한다. 제안하는 DAC는 0.35 μm Hynix CMOS 공정을 사용하여 설계 및 레이아웃을 하였으며, 응용되는 시스템의 속도, 해상도 및 면적 등의 사양을 고려하여 전류 모드 구조로 적용되었다. D/A 변환기의 선형 특성은 설계한 Spec. 과 유사하였으며, 0.09LSB 정도의 DNL과 INL오차가 측정되었다. 제작된 칩 테스트 결과에 대한 오동작의 원인을 분석하였으며, 이를 통하여 칩 테스트를 위한 고려사항 등을 제안하였다.
SiGe 에피 공정기술을 이용하여 제작된 초 접합 금속- 산화막 반도체 전계 효과 트랜지스터의 시뮬레이션 연구
이훈기,최철종,박양규,심규환 한국반도체디스플레이기술학회 2014 반도체디스플레이기술학회지 Vol.13 No.3
In this paper, we propose a super-junction MOSFET (SJ MOSFET) fabricated through a simple pillar forming process by varying the Si epilayer thickness and doping concentration of pillars using SILVACO TCAD simulation. The design of the SJ MOSFET structure is presented, and the doping concentration of pillar, breakdown voltage (VBR) and drain current are analyzed. The device performance of conventional Si planar metal-oxide semiconductor field-effect transistor(MOSFET), Si SJ MOSFET, and SiGe SJ MOSFET was investigated. The p- and n-pillars in Si SJ MOSFET suppressed the punch-through effect caused by drain bias. This lead to the higher VBR and reduced on resistance of Si SJ MOSFET. An increase in the thickness of Si epilayer and decrease in the former is most effective than the latter. The implementation of SiGe epilayer to SJ MOSFET resulted in the improvement of VBR as well as drain current in saturation region, when compared to Si SJ MOSFET. Such a superior device performance of SiGe SJ MOSFET could be associated with smaller bandgap of SiGe which facilitated the drift of carriers through lower built-in potential barrier.
이훈기,김희식 사단법인 인문사회과학기술융합학회 2017 예술인문사회융합멀티미디어논문지 Vol.7 No.9
In this paper an excitation system which is effective for improving the start-up characteristic of synchronous motors has been discussed in this study. Excitation system is a system that maintains/controls the voltage of an output terminal(s) by supplying direct current to a field coil. The excitation control system of synchronous motor should be able to achieve stabilization (i.e., power factor 1) as rapidly possible by controlling excitation current in accordance with the control mode applied. When a direct current is passed through the field winding of the rotor, the rotation is restrained in the rotor. When the field current is caused to flow before the synchronous speed, the pulling forces and the forces pushing each other are repeated and the vibration becomes severe. Especially, on an occasion where current flows into the rotor field coil without synchronizing the speed of rotor with the rotating field when starting a synchronous motor, the motor will not start due to vibration. Existing analog excitation systems supply field current after measuring the induced voltage first and then the speeds mentioned above have been synchronized. In this case, the field current will be supplied with some time delay. However, as this method depends on a timer, there's a possibility the field breaker would kick in too early or does not start at all due to its failure or malfunction. For this reason, a digital excitation system has been proposed to solve the issues of reliability involved in generator start-ups. This new system can secure stable start ups by adopting the method that estimates and determines an appropriate point of time for current to be led into the field coil based on the slip calculation using both the input voltage and induced voltage frequencies. 본 논문에서는 동기전동기의 기동 특성 개선을 위한 여자시스템에 대하여 현장 실험을 하였다. 여자시스템은 계자권선에 직류 전류를 공급하여 출력 단자전압을 일정하게 유지하고, 조정하는 시스템이다. 동기전동기의 여자 제어 시스템은 제어 모드에 따라 여자 전류를 제어함으로써 가능한 한 신속하게, 역률 1의 상태로 안정화 시켜야 한다. 회전자의 계자권선에 직류전류를 흘리면 회전자는 회전자속에 구속된다. 동기속도 이전에 계자 전류를 흘리면 서로 당기는 힘과 서로 미는 힘이 반복되어 진동이 심하게 된다. 특히나 동기전동기의 기동시 회전자와 화전자계의 속도를 동기화하지 않고 회전자 계자권선에 전류를 흘리는 경우 진동이 발생되어 결과적으로 기동실패로 이어 질 수 있다. 기존 여자시스템들의 경우에는 아날로그 기반으로 기동 시 계자권선에 유기전압을 측정하지 않고 회전자와 회전자계가 동기화 되었을 때 시간지연을 주어 계자전류를 공급하였다. 하지만 기존 시스템은 79년도에 설치된 아날로그 시스템으로서 유지 보수가 어렵고, 고장 발생시 대체할 제품이 없어 기동을 할 수 없다. 고장시 기동을 할 수 없게 되면 막대한 손실이 발생하게 된다. 이러한 문제점을 해결하고, 동기전동기 기동시 슬립을 측정하여 불필요한 기동 시간을 줄이고, 시스템의 안정적인 기동을 보장 할 수 있다.
이훈기,한미경,장종현,Lee, H.K.,Han, M.K.,Jang, J.H. 한국전자통신연구원 2017 전자통신동향분석 Vol.32 No.5
In this paper, a video conferencing system, which has been attracting significant attention as an immersive telepresence service owing to the recent emergence of 5G networks, is described. We propose a service platform for Giga Media based video conferencing for 5G convergence services. The video conferencing service consists of a traditional structure that provides information exchange through the transmission of video and voice of remote participants using a Multipoint Control Unit (MCU), a browser-based video conferencing based on WebRTC, a multi-view point video conferencing, and holographic telepresence centered on mixed reality. The paper introduces the trends and detailed structures of various technologies used in the video conferencing system, and compares the video conferencing system technologies and video conferencing service characteristics for the integrated Giga Media platform.
이훈기,김태윤,김효빈,황성호 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4
Recently, various studies have been conducted to apply deep learning and AI to various fields of autonomous driving, such as recognition, sensor processing, decision-making, and control. This paper proposes a controller applicable to path following, static obstacle avoidance, and pedestrian avoidance situations by utilizing reinforcement learning in autonomous vehicles. For repetitive driving simulation, a reinforcement learning environment was constructed using virtual environments. After learning path following scenarios, we compared control performance with Pure-Pursuit controllers and Stanley controllers, which are widely used due to their good performance and simplicity. Based on the test case of the KNCAP test and assessment protocol, autonomous emergency steering scenarios and autonomous emergency braking scenarios were created and used for learning. Experimental results from zero collisions demonstrated that the reinforcement learning controller was successful in the stationary obstacle avoidance scenario and pedestrian collision scenario under a given condition.
Survival Probability Dynamics of Scaled Brownian Motion: Effect of Nonstationary Property
이훈기,송상근,김지현,성재영 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.9
Scaled Brownian motion (SBM) is a popular model of nonstationary anomalous diffusion process. We here extend the SBM model to investigate the survival probability of stationary anomalous diffusion process. By making comparison between the SBM model and the stationary SBM model, we investigate the effect of stationarity on the first passage kinetics.