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Lee, Sung-Hyun,Kim, Hye-Rim,Lee, Taeseon,Lee, Haemin,Lee, Jinwoo,Lee, Jaegeun,Park, Junbeom,Lee, Kun-Hong Elsevier 2017 Carbon Vol.124 No.-
<P>Carbon nanotube (CNT) fibers were synthesized from ethylene, acetylene, or methane by separately injecting ferrocene and the carbon precursors during a direct spinning process. Ethylene and acetylene have low decomposition temperatures. It was difficult to synthesize CNT fibers from these precursors using the direct spinning method. CNT fibers were continuously synthesized by delaying the contact time between the catalyst particles and the carbon precursors, which provided sufficient time for catalyst growth. Changes in catalyst size from 2 nm to 20 nm were observed as a function of the catalyst formation step setting temperature (350-440 degrees C) and the carbon precursor injection tube length (8-310 mm), and the relationship between the catalyst size and the CNT diameter was characterized. The CNT fibers had higher I-G/I-D ratios when synthesized from acetylene (69.87) or ethylene (18.52) than from methane (3.61). The choice of the carbon precursor had a much larger effect on the I-G/I-D ratio of the synthesized CNT fibers than the other operating variables. (C) 2017 Elsevier Ltd. All rights reserved.</P>
항공기 탑재 AESA 레이다의 통합 항법 성능 분석 연구
이동연(Dong-Yeon Lee),권혁준(Hyeokjoon Kwon),이동욱(Donguk Lee),이해민(Haemin Lee),정영광(Youngkwang Jung),정재현(Jaehyeon Jeong),박상규(Sanggyu Park),이성원(Sungwon Lee),박준현(June Hyune Park),탁민제(Min-Jea Tahk),방효충(Hyochoong 한국항공우주학회 2021 韓國航空宇宙學會誌 Vol.49 No.4
기존 레이다 시스템에 비해 다양한 이점을 제공하는 능동 위상 배열 (AESA) 레이다의 성공적인 운용을 위해서는 정확하고 강건한 항법이 중요하다. 본 논문은 AESA 레이다를 탑재한 항공기의 EGI 시스템을 기반으로 한 통합 항법의 성능 분석에 대한 연구를 소개한다. GPS 및 IMU 입력을 생성하는 모델이 개발되었고, GPS/IMU 약결합 항법 필터가 구성되었다. GPS/IMU 모델 및 항법필터와 함께 6자유도 항공기 시뮬레이터를 사용하여 항법 성능을 평가하는 절차가 소개되었다. 성능 분석 절차의 단계는 사례 연구와 함께 설명되었다. For successful operations of an airborne Active Electronically-Scanned Array (AESA) radar, which has various advantages over traditional radar systems, accurate and robust navigation is critical. This paper discusses a study on the performance analysis of an integrated navigation based on the Embedded GPS/INS (EGI) system for an aircraft equipped with an AESA radar. The models for generating the inputs for the GPS/IMU are developed. A navigation filter for a loosely-coupled GPS/IMU system is constructed. Overall navigation performance assessment procedure using a six degree of freedom aircraft simulator – along with the GPS/IMU models and the navigation filter – is introduced. The steps of the performance analysis procedure are explained using a comprehensive case study.
Quantitative Measures of Output Noise Sensitivities of Linear Systems in Modal Domain
Haemin Lee,Youngjin Park 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Controllability and observability are a structural property that carries information useful for control system design. There are many measures to determine the location of actuator and sensor like degree of controllability(DOC), degree of observability(DOO) and degree of disturbance rejectability(DODR). However, for a system which uses both actuators and sensor, the placement of actuator can be affected by the placement of sensor and vice versa. Therefore, the measure which can consider both controllability and observability simultaneously is defined and it is called degree of compensation capability(DOCC) and degree of output noise sensitivity(DONS). DONS is a measure that represents the effect of output noise to control input and it can be represented by the inverse of the product of controllability and observability Gramian. DONS is applied to the modal domain system in this paper and numerical example is shown to demonstrate the usefulness of the proposed measures.
Truthful Electric Vehicle Charging via Neural-Architectural Myerson Auction
Haemin Lee,Soyi Jung,Joongheon Kim 한국통신학회 2021 ICT Express Vol.7 No.2
The electric vehicle (EV) market increases due to the benefits of reducing greenhouse gas emissions using renewable energy resources. In this context, the charging scheme of electric vehicles in charging stations (CSs) is also important. Electronic devices’ charging between EV and multiple CS should consider EV’s short battery capacity, long charging time, residual energy in each CS, and time of use (ToU) for charging. In this paper, multiple CSs compete to offer electricity charging to a single EV. Based on this need, this paper proposes a deep learning-based auction which increases the charging amounts using Myerson auction while preserving truthfulness.
Degree of controllability for linear unstable systems
Lee, Haemin,Park, Youngjin SAGE Publications 2016 Journal of vibration and control Vol.22 No.7
<P>The degree of controllability is a measure to check how controllable a given system is, which makes up for the weak points of traditional methods for checking controllability. There are many definitions of the degree of controllability, and the most widely used measure is represented by controllability Gramian. This measure has physical meaning of minimum input energy to change the states. However, it is hard to use this method for unstable systems because the steady-state value of Gramian cannot be defined. Therefore, the degree of controllability for unstable systems is proposed in this paper. The definition of the measure is minimum control input energy to change the state from an arbitrary initial condition to an arbitrary final condition. The derivation result shows that the measure is the sum of two terms, one represented by Gramian of a stable subsystem and the other represented by Gramian of a subsystem that has mirror image poles of an anti-stable subsystem. These Gramians can be obtained by solving two Lyapunov equations. A simple numerical example shows the usefulness of the proposed measure of degree of controllability.</P>