• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.41-43
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• 2005

PDA-based monitoring is used to acquire continuously the patient's vital signs, including electrocardiography, activity, heart rate and $SpO_2$. In this paper, A biomedical signal acquisition device was designed using 3-axial MEMS accelerometer and 1-ch ECG amplifier, to have the function of monitoring activity and electrocardiography. The proposed system is composed of transmitter and receiver. Through the Zigbee communication, subject's biosignals can be transmitted in real-time to receiver, and transmitted data confirmed using PDA. The packet size used in this device was set not to exceed a maximum payload size of 116 byte. One packet consists of two segments. The transmission speed was 21 packet per second, 420 ECG samples per second, and 42 acceleration samples per second. The proposed method can be used to develop Activities of Daily Living(ADL} monitoring devices for the elderly or movement impaired people and enables patients to be monitored without any constraints. Also, this method will reduce medical costs in the aged society.

• 전자공학회논문지T
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• 제36T권4호
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• pp.88-93
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• 1999

본 논문에서는 한방의료에서 인체 전신의 상태를 파악하는데 주요한 요소인 맥파를 과학적으로 관찰하고자 스트레인 게이지를 이용하여 맥파를 검출하는 새로운 시스템을 구성하였다. 스트레인 게이지는 센서의 변형에 대해 선형적으로 고유한 저항값이 변화되므로 손목에서 맥의 변화는 스트레인 게이지를 이용하여 맥파의 파형으로 검출할 수 있다. 맥파 검출 시스템의 구성에서 스트레인 게이지로부터 발생된 저항변화값을 검출하기 위해 정밀 브리지회로와 고감도 증폭회로를 설계, 제작하였으며 이 시스템으로 미세한 맥의 변화를 상응하는 전압파형으로 출력시킨다. 구성된 시스템을 이용하여 6인의 맥을 직접 검출하고 시간영역과 주파수 영역에서 맥의 특성을 관찰하므로써 본 연구에서 구성된 맥파 검출 시스템의 과학적인 효용성을 입증하였다.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1844-1854
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• 2003

This paper discusses details of modeling and robust control of an AMB (active magnetic bearing) spindle, and part I presents a modeling and validation process of the AMB spindle. There are many components in AMB spindle : electromagnetic actuator, sensor, rotor, power amplifier and digital controller. If each component is carefully modeled and evaluated, the components have tight structured uncertainty bounds and achievable performance of the system increases. However, since some unknown dynamics may exist and the augmented plant could show some discrepancy with the real plant, the validation of the augmented plant is needed through measuring overall frequency responses of the actual plant. In addition, it is necessary to combine several components and identify them with a reduced order model. First, all components of the AMB spindle are carefully modeled and identified based on experimental data, which also render valuable information in quantifying structured uncertainties. Since sensors, power amplifiers and discretization dynamics can be considered as time delay components, such dynamics are combined and identified with a reduced order. Then, frequency responses of the open-loop plant are measured through closed-loop experiments to validate the augmented plant. The whole modeling process gives an accurate nominal model of a low order for the robust control design.

• 한국ITS학회 논문지
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• 제11권2호
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• pp.83-91
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• 2012

TV 대역 White Space 송수신기에서 스펙트럼 센싱을 위한 RF 에너지 검출기 구조를 제안하였다. 제안된 에너지 검출기는 RF 능동 필터 구조에 기반하며, RF 저잡음 증폭기에 고역통과필터를 포함하는 피드포워드 루프를 추가함으로써 원하는 RF 주파수 성분만 통과시키고 그 외의 대역은 감쇄시키는 동작을 수행한다. 본 연구에서는 기존의 구조가 갖는 단점인 단측파 대역만 억압할 수 있는 문제를 해결하고자 양측파 대역을 동시에 억압할 수 있는 새로운 구조를 제안하였고, 간단한 시스템 모델링을 통해 구성요소의 Non-ideality에 의한 RF 에너지 검출기 성능에 대한 영향을 평가하였다. 또한, 시스템 시뮬레이션을 통해 양측파대역이 효과적으로 감쇄되어 RF 에너지 검출기로서 동작할 수 있음을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2201-2216
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• 2015

Peak to average power ratio (PAPR) is one of the main imperfections in the broadband communication systems with multiple carriers. In this paper, a new crest factor reduction (CFR) scheme based on interleaved phase sequence called Dummy Sequence Insertion Enhanced Partial Transmit Sequence (DSI-EPTS) is proposed which effectively reduces the PAPR while at the same time keeps the total complexity low. Moreover, the prototype of the proposed scheme in field programmable gate array (FPGA) is demonstrated. In DSI-EPTS scheme, a new matrix of phase sequence is defined which leads to a significant reduction in hardware complexity due to its less searching operation to extract the optimum phase sequence. The obtained results show comparable performance with slight difference due to the FPGA constraints. The results show 5 dB reduction in PAPR by applying the DSI-EPTS scheme with low complexity and low power consumption.

• 센서학회지
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• 제6권2호
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• pp.145-154
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• 1997

회로 시뮬레이션과 국부적 탐색을 갖는 시뮬레이티드 아닐링을 사용한 새로운 탐색 전략에 기초하여 고성능 연산 증폭기의 설계 자동화를 위한 기법을 제안하였다. 임의의 연산 증폭기 구조와 성능 규격에 대해서, 이산 설계 변수들을 갖는 비용 함수의 이산 최적화를 통해 연산 증폭기의 설계가 이루어진다. 설계 시간의 단축을 위해서 전용 회로 시뮬레이터와 몇 가지 휴리스틱을 사용하였다. 스마트 센서와 10 비트 25 MS/s 파이프라인 A/D 변환기에 사용 가능한 저전력 고속 전차동 CMOS 연산 증폭기의 설계를 통해서, 제안된 기법을 사용하여 개발된 설계 도구는 적은 설계 지식과 설계 노력을 가지고 고성능 연산 증폭기를 설계하는데 사용될 수 있음을 보였다.

• 한국소음진동공학회논문집
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• 제26권1호
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• pp.82-88
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• 2016

This paper proposes a new type of semi-active direct-drive valve(DDV) car suspension system using piezoelectric actuator associated with displacement amplifier. As a first step, controllable piezoelectric DDV damper is designed and governing equation of a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the piezostack DDV damper is constructed. After deriving the equations of the motion, in order to control spool displacement and damping force the skyhook controller is designed and applied. The performance evaluation of the proposed semi-active suspension system is conducted with different displacement of spool. Then, the ride comfort analysis is undertaken in time domain with bump road profile.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.90-95
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• 2000

This paper presents the vergence control of a parallel stereo camera and its application to underwater stereo camera to enhance the working efficiency of underwater vehicles that equips with manipulators in seabed operation. The stereo camera consists of two parallel lenses mounted on a lateral moving base and two CCD cameras mounted on a longitudinal moving base, which is embedded in a small pressure canister for underwater application. Because the lateral shift is related to the backward shift with a nonlinear relation, only one control input is needed to control the vergence and focus of the camera with a special driving device. We can get a clear stereo vision with the camera for all the range of objects in air and in water, especially in short range objects. The control system of the camera is so simple that we are able to realize a small stereo camera system and to apply it to a stereo vision system for underwater vehicles. This paper also shows how to acquire the distance information of an underwater object with this stereo camera. Whenever we focus on an underwater object with the camera, we can obtain the three-dimensional images and the distance information in real-time.

• 한국정보통신학회논문지
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• 제9권6호
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• pp.1356-1363
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• 2005

FOG(fiber optic gyroscope :광섬유 자이로스코프)는 소형 경량화, 신속한 가동, 저 전력 소모 및 저렴한 가격으로 실현 가능하므로 자이로콤파스시스템에서의 선호도가 높아지고 있다. 본 논문에서는 FOG를 기반으로 하며, 자이로콤파스시스템에 적용할 수 있는 디지털 진북추종 방식을 제안한다. FOG의 earth signal의 해석모델을 분석하고, lock-in증폭기를 통과한 earth signal을 모델링 한다. 두 개의 lock-in증폭기 출력신호를 이용한 진북추종 알고리즘을 개발하고, 이 알고리즘에 의한 디지털 진북추종 방식을 제안한다. 제안한 방식의 성능을 증명하기 위해 컴퓨터시뮬레이션 결과를 포함한다.

• Journal of Power Electronics
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• 제11권4호
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• pp.471-478
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• 2011

This paper addresses the establishment of a kVA-range plug-in hybrid electrical vehicle (PHEV) integration test platform and associated issues. Advancements in battery and power electronic technology, hybrid vehicles are becoming increasingly dependent on the electrical energy provided by the batteries. Minimal or no support by the internal combustion engine may result in the vehicle being occasionally unable to recharge the batteries during highly dynamic driving that occurs in urban areas. The inability to sustain its own energy source creates a situation where the vehicle must connect to the electrical grid in order to recharge its batteries. The effects of a large penetration of electric vehicles connected into the grid are still relatively unknown. This paper presents a novel methodology that will be utilized to study the effects of PHEV charging at the sub-transmission level. The proposed test platform utilizes the power hardware-in-the-loop (PHIL) concept in conjunction with high-fidelity PHEV energy system simulation models. The battery, in particular, is simulated utilizing a real-time digital simulator ($RTDS^{TM}$) which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces via a LC-LC-type filter to a power grid. In addition, the PHEV impact is evaluated via another power electronic converter controlled through $dSPACE^{TM}$, a rapid control systems prototyping software.