• 드라이브 ㆍ 컨트롤
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• 제13권2호
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• pp.26-33
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• 2016

This paper describes of a mathematical and real experimental analysis for a walking robot which uses servo valve driven hydraulic actuator. Recently, many researchers are developing a walking robot based on hydraulic systems for the difficult and dangerous missions such as walking in the rough terrain and carrying a heavy load. In order to design and control a walking robot, the characteristics of the hydraulic actuators in the joint through the view point of walking such as controllability and backdrivability must be analyzed. A general mathematical model was used for analysis and proceeds to position and pressure changes characteristic of the input and backdrivability experiment. The result shows the actuator is a velocity source, had a high impedance, the output stiffness is high in contact with the rigid external force. So stand above the controller and instruments that complement the design characteristics can be seen the need to apply a hydraulic actuator in walking robot.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.39-47
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• 2018

Recently, as environmental regulations for earth-moving equipment have been tightening, advanced systems such as electronic control, have been introduced for energy savings. An IMV (Independent Metering Valve) consisting of four 2-way valves, is an electro-hydraulic control systems that provides more flexible controllability, and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully maximize use of an IMV, the bi-directional flow control valve that can regulate a large amount of flow in both directions, should be adopted. The hydraulic circuit of an IMV applied to an excavator from an overseas construction equipment company, reveals the flow control valve with the compound of proportional solenoid valve for first stage, and 2-way spool valve for the second stage. Moreover, the two spools are interconnected by a feedback spring, presumed to compensate for flow force acting on the second stage spool. This paper addresses the static analysis of flow control valve in an IMV to investigate the improvement of robustness, against flow force by the feedback spring. From the steady-state analysis of flow control valve model, it can be concluded that the feedback spring facilitates maintaining linearity of spool displacement for control input, and relatively constant flow for load disturbance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1983-1989
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• 2005

Industrial robots are powerful, extremely accurate multi-jointed systems, but they are heavy and highly rigid because of their mechanical structure and motorization. Therefore, sharing the robot working space with its environment is problematic. A novel pneumatic artificial muscle actuator (PAM actuator) has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. Its main advantages are high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks. The PAM is undoubtedly the most promising artificial muscle for the actuation of new types of industrial robots such as Rubber Actuator and PAM manipulators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. In addition, the nonlinearities in the PAM manipulator still limit the controllability. Therefore, it is not easy to realize motion with high accuracy and high speed and with respect to various external inertia loads in order to realize a human-friendly therapy robot To overcome these problems a novel controller, which harmonizes a phase plane switching control method with conventional PID controller and the adaptabilities of neural network, is newly proposed. In order to realize satisfactory control performance a variable damper - Magneto-Rheological Brake (MRB) is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control using neural network brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control using neural network and without regard for the changes of external inertia loads.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.1-8
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• 2019

The HPM (High-speed Power Matching) system is an electro-hydraulic control system. It directly controls the swash plate of the pump by selecting four-loop logic based on joystick signals, pump flow, and pressure signal to improve the efficiency and controllability of construction machines. In the NFC (Negative Flow Control) system, a typical pump control system using conventional open center type MCV, the loss is continuously generated by flow through the center bypass line even when the excavator is not in operation. Also, due to the slow response of the pump that indirectly controls the flow rate using the pressure regulator, peak pressure occurs at the start or stop of the operation. Conversely, the HPM system uses an MCV without center-by-pass flow path and the swash plate of a pump for the HPM is controlled by a high-speed proportional flow control valve. As a result, the HPM system minimizes energy loss in standby state of the excavator and enables peak pressure control through rapid electro-hydraulic control of a pump. In this paper, the concept of the HPM system algorithm is introduced and the hydraulic system efficiency is compared with the NFC system using the excavator SAT (System Analysis Tool).

• 한국통신학회논문지
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• 제26권11C호
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• pp.148-156
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• 2001

본 논문에서는 RISC 마이크로프로세서에 DSP프로세서를 추가하여 멀티미디어 기능이 강화된 응용에 알맞은 마이크로프로세서(YS-RDSP)를 제안한다. YS-RDSP는 최대 4개의 명령어를 동시에 병렬로 처리할 수 있다. 프로그램의 크기를 줄이기 위해 YS-RDSP는 16비트와 32비트의 두 가지 명령어 길이를 지원한다. YS-RDSP는 칩 하나로 RISC마이크로프로세서의 programmability 및 제어능력에 DSP의 처리능력을 제공하기 위하여 8-KByte ROM과 8-KByte RAM을 내장하고 있다. 칩 내에 있는 주변장치중 하나인 시스템 컨트롤러는 저전압 동작을 위한 3가지의 전압강하모드를 지원하며 SLEEP명령어는 CPU코어와 주변장치의 동작상태를 변환시킨다. YS-RDSP프로세서는 Verilog-HDL를 이용하여 하향식설계방식으로 구현되었고 C-언어로 작성된 사이클 단위 시뮬레이터를 이용하여 개선되고 검증되었다. 검증된 모델은 0.6um, 3.3V CMOS 표준 셀 라이브러리로 합성되었으며 자동화 P&R에 의해 10.7mm8.4mm코어 면적을 갖도록 레이아웃 되었다.

• 전력전자학회논문지
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• 제12권4호
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• pp.318-323
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• 2007

본 논문에서는 영구자석형 5상 전동기(Five-phase permanent magnet motor)의 약계자 제어에 대한 연구를 수행한다. 제안된 전동기는 집중권 방식의 권선분포를 가지고 있고 사다리꼴 형태의 역기전력을 나타내고 있으며, 사다리꼴 형태의 전류를 인가하기 위하여 사인파의 기본파 성분에 3고조파 성분을 첨가하였다. 따라서 BLDC 전동기(Brushless dc motor)와 등가적으로 같은 평균토크를 발생시키면서 BLDC 전동기의 단점을 극복할 수 있었다. 전동기 전류의 토크성분과 자속성분은 다중 레퍼런스 프래임을 이용하여 분리할 수 있었으며, 결과적으로 쉽게 벡터제어가 이루어질 수 있었다. 사용된 전동기는 고속영역에서부터 저속영역까지 BLDC 전동기와 같이 높은 토크 밀도를 가지며, 약계자 영역이나 고속영역에서 영구자석형 전동기와 같이 제어의 용이함을 가진다는 장점을 가지고 있으며 실험결과를 통하여 제안된 전동기와 알고리즘을 검증하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.253-253
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• 2012

Low temperature SiOx film process has being required for both silicon and oxide (IGZO) based low temperature thin film transistor (TFT) for application of flexible display. In recent decades, from low density and high pressure such as capacitively coupled plasma (CCP) type plasma enhanced chemical vapor deposition (PECVD) to the high density plasma and low pressure such as inductively coupled plasma (ICP) and electron cyclotron resonance (ECR) have been used to researching to obtain high quality silicon oxide (SiOx) thin film at low temperature. However, these plasma deposition devices have limitation of controllability of process condition because process parameters of plasma deposition such as RF power, working pressure and gas ratio influence each other on plasma conditions which non-leanly influence depositing thin film. In compared to these plasma deposition devices, neutral beam assisted chemical vapor deposition (NBaCVD) has advantage of independence of control parameters. The energy of neutral beam (NB) can be controlled independently of other process conditions. In this manner, we obtained NB dependent high crystallized intrinsic and doped silicon thin film at low temperature in our another papers. We examine the properties of the low temperature processed silicon oxide thin films which are fabricated by the NBaCVD. NBaCVD deposition system consists of the internal inductively coupled plasma (ICP) antenna and the reflector. Internal ICP antenna generates high density plasma and reflector generates NB by auger recombination of ions at the surface of metal reflector. During deposition of silicon oxide thin film by using the NBaCVD process with a tungsten reflector, the energetic Neutral Beam (NB) that controlled by the reflector bias believed to help surface reaction. Electrical and structural properties of the silicon oxide are changed by the reflector bias, effectively. We measured the breakdown field and structure property of the Si oxide thin film by analysis of I-V, C-V and FTIR measurement.

• 한국정보통신학회논문지
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• 제16권4호
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• pp.793-798
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• 2012

본 연구에서는 이중게이트(Double Gate; DG) MOSFET에서 채널 내 도핑분포 및 채널구조에 따른 문턱전압이하 전류의존성을 분석하고자 한다. 전위분포를 구하기 위하여 포아송방정식을 풀 때 전하분포는 가우스분포함수를 이용할 것이며 이의 타당성은 이미 여러 논문에서 입증하였다. 이중게이트 MOSFET는 게이트전압에 의한 전류제어능력의 증가로 단채널 효과를 감소시킬 수 있어 문턱전압이하 특성을 향상시킬 수 있다. 문턱전압이하 영역에서 전류제어는 고집적회로에서 소비전력의 감소와 관계된 매우 중요한 요소이다. 게이트전압에 따른 문턱전압이하 전류의 변화를 이용하여 문턱전압의 변화를 정량적으로 분석할 것이다. 문턱전압이하 전류는 채널 내 도핑분포 및 채널크기에 의하여 영향을 받는다. 그러므로 본 연구에서는 채널길이 및 채널두께의 변화가 전류흐름에 미치는 영향을 채널도핑농도, 도핑분포함수 등에 따라 분석할 것이다.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.326-335
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• 2017

It is known that diesel engines have the disadvantage of high emission levels of NOx and PM. Therefore, many combustion strategies have been developed to reduce these harmful NOx and PM emissions in a diesel engine. Among these strategies, HCCI(Homogeneous Charge Compression Ignition) and PCCI(Premixed Charge Compression Ignition) are the most popular as these can reduce NOx and PM simultaneously. However, when a single fuel like diesel is applied, it is difficult to control the combustion phase and this can lead to power reduction. In this study, premixed gasoline and pilot diesel were used to overcome the problems of controllability of the combustion phase and harmful emissions. We injected gasoline directly into the combustion chamber and the gasoline/air mixture was ignited with a pilot diesel fuel near the top dead center. The results showed that the combustion and emission characteristics of dual-fuel combustion were comparable to those of conventional diesel combustion. When we applied the dual-fuel PCCI combustion concept, more than 90 % of NOx and PM emission was reduced simultaneously without significant degradation of efficiency compared to conventional diesel combustion.

• 한국항행학회논문지
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• 제13권1호
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• pp.48-53
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• 2009

본 논문은 1P8M CMOS $0.13{\mu}m$ 공정을 이용하여 GPS응용에 적합한 프론트-엔드(front-end)를 구현하였다. 저잡음 증폭기(LNA)는 능동 안테나와 수동 안테나를 지원하기 위해 높은 전압이득과 낮은 잡음지수(Noise Figure)의 LNA1모드와 낮은 이득과 높은 입력 3차 교차점(IIP3: 3rd Input Intercept Point)의 LNA2모드로 동작한다. 두 LNA의 측정된 성능은 1.2 V의 공급전압에서 각각 3.2/2 mA의 전류를 이용하여 16.4/13.8 dB 이득과, 1.4/1.68 dB NF, 그리고 -8/-4.4 dBm의 IIP3값을 갖는다. 쿼드 하향주파수 혼합기(quadrature downconversion 혼합기)는 트랜스임피던스 증폭기(transimpedance amplifier)와 가변저항을 이용하여 27.5 dB에서 41 dB의 변환이득을 갖는다. 프론트-엔드는 LNA1모드 동작 시 6.6 mW의 전력을 소모하여 39.8 dB의 변환이득, 2.2 dB의 잡음지수와 -33.4 dBm의 IIP3의 성능을 갖는다.