• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.34-39
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• 1993

Presented in this paper is a complete error covariance analysis for strapdown inertial navigation system(SDINS). We have found that in SDINS the cross-coupling terms in gyrocompass alignment errors can significantly influence the SDINS error propagation. Initial heading error has a close correlation with the east component of gyro bias erro, while initial level tilt errors are closely related to accelerometer bias errors. In addition, pseudo-state variables are introduced in covariance analysis for SDINS utilizing the characteristics of gyrocompass alignment errors. This approach simplifies the covariance analysis because it makes the initial error covariance matrix to a diagonal form. Thus a real implementation becomes easier. The approach is conformed by comparing the results for a simplified case with the covariance analysis obtained from the conventional SDINS error model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1947-1948
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• 2008

This paper presents the implementation of Power Line Communication(PLC) module which can reduce standby-power consumption. The suggested PLC module consists of PLC modem, coupling circuit, ZCP(Zero-Cross Point) Circuit and main SMPS control relay. The test results under power line communication test-bed used home appliance show the 77% saving of standby-power.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.138-148
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• 1998

The aim of the work described in this paper is to develop a complex underground acoustic system which detects and localizes the origin of an underground hammering sound using an array of hydrophones located about loom underground. Three different methods for the sound localization will be presented, a time-delay method, a power-attenuation method and a hybrid method. In the time-delay method, the cross correlation of the signals received from the way of sensors is used to calculate the time delays between those signals. In the power-attenuation method, the powers of the received signals provide a measure of the distances of the source from the sensors. A new hybrid method has been developed for estimating the origin of the underground acoustic source by coupling both methods. The Nelder-Meade simplex search algorithm is then used to numerically estimate the position of the source in those methods. For each method the sound localization is carried out in three dimensions underground. The distance between the true and estimated origins of the source is in some cases less than 6m for a search area of radius 250m.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.139-146
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• 1998

The prototype ASME III motor actuated Y-type globe valve has been tested to identify dynamic characteristics. The valve is Seismic Category I equipment and has the function to control water flow in the safety-related system. In this study, two different types of structural identification test i.e. swept sine and broadband random, have been performed at various levels of excitation to verify the effects of test method and excitation level on cross coupling effect as well as natural frequencies and damping values. It was found that swept sine test and broadband random test showed similar natural frequencies, and that the primary interaction was exhibited between horizontal and vertical axes.

• Journal of Power Electronics
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• 제15권1호
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• pp.190-201
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• 2015

This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary ${\alpha}-{\beta}$ reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.

• Journal of Biosystems Engineering
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• 제36권6호
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• pp.476-483
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• 2011

The aerial application using an unmanned helicopter has been already utilized and an attitude controller would be developed to enhance the operational convenience and safety of the operator. For a preliminary study of designing flight controller, a state space model for an RC helicopter would be identified. Frequency sweep flight tests were performed and time history data were acquired in the previous study. In this study, frequency response of the flight test data of a small unmanned helicopter was analyzed by using the CIFER software. The time history flight data consisted of three replications each for collective pitch, aileron, elevator and rudder sweep inputs. A total of 36 frequency responses were obtained for the four control stick inputs and nine outputs including linear velocities and accelerations and angular velocities in 3-axis. The results showed coherence values higher than 0.6 for every primary control inputs and corresponding on-axis outputs for the frequency range from 0.07 to 4 Hz. Also the analysis of conditioned frequency response showed its effectiveness in evaluating cross coupling effects. Based on the results, the dynamic characteristics of the model helicopter can further be analyzed in terms of transfer functions and the undamped natural frequency and damping ratio of each critical mode.

• 대한시과학회지
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• 제20권4호
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• pp.513-521
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• 2018

목적 : 이 연구에서는 도파민이 적용된 히알루론산 가교 하이드로겔을 제조하고 항산화 활성을 조사하였다. 방법 : 먼저 히알루론산과 p(HEMA)로 구성된 상호침투고분자구조로 후처리 한 p(HEMA) 기반 하이드로겔을 제조하였다. 다음으로 아마이드 결합반응을 통해 도파민이 적용된 항산화 하이드로겔을 제조하였다. 항산화 활성의 평가는 ABTS 와 DDPH 라디칼 소거능 방법을 사용하였다. 결과 : 도파민이 적용된 하이드로겔은 유의한 항산화 활성을 나타내었다. 히알루론산의 가교는 하이드로겔 표면의 습윤성을 개선시킨 반면에 도파민이 적용된 하이드로겔은 대조군과 비교하여 유의한 차이를 나타내지 못했다. 도파민이 적용된 하이드로겔은 높은 광투율을 나타내었다. (>88%) 결론 : 도파민이 결합된 히알루론산의 가교에 기초한 항산화 하이드로겔의 개발이 안의료 및 생물의학 재질 개발에 도움을 줄 수 있을 것으로 사료된다.

• Wind and Structures
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• 제6권5호
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• pp.387-402
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• 2003

In the past decades, much effort has been made towards the study of single-mode-based vibration controls with dynamic energy absorbers such as single or multiple Tuned Mass Dampers(TMDs). With the increase of bridge span length and the tendency of the bridge cross-section being more slender and streamlined, multi-mode coupled vibrations as well as their controls have become very important for large bridges susceptible to strong winds. As a simple but effective device, the TMD system especially the semi-active one has become a promising option for such coupled vibration controls. However, despite various studies of optimal controls of single-mode-based vibrations with TMDs, research on the corresponding controls of the multi-mode coupled vibrations is very rare so far. For the development of a semi-active control strategy to suppress the multi-mode coupled vibrations, a comprehensive parametric analysis on the optimal variables of this control is substantial. In the present study, a multi-mode control strategy named "three-row" TMD system is discussed and the general numerical equations are developed at first. Then a parametric study on the optimal control variables for the "three-row" TMD system is conducted for a prototype Humen Suspension Bridge, through which some useful information and a better understanding of the optimal control variables to suppress the coupled vibrations are obtained. This information lays a foundation for the design of semi-active control.

• 한국정보통신학회논문지
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• 제13권3호
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• pp.514-521
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• 2009

영구자석 매입형 동기 전동기(IPM : Interior-mounted Permanent Magnet Motor)의 전류제어는 릴럭턴스에 의존하는 최대토크 특성 때문에 표면부착형 동기전동기(SPM : Surface-mounted Permanent Magnet Motor)보다 더 복잡하다. 그러므로 고성능 토크제어를 위해서는 d축 전류와 q축 전류의 상태 디커플링이 필요하다. 하지만 상태들 사이에 영향을 미치는 인덕턴스의 변화 때문에 상태 디커플링이 어렵다. 그러므로 이 변화에 대처할 수 있는 상태 디커플링 방법의 개발이 필요하며 이를 이용한 전류의 독립제어가 필요하다. 본 논문에서는 IPM모터 에 대하여 가상 상태를 갖는 슬라이딩 모드 제어를 이용하여 상태 디커플링이 가능한 접근법을 제안한다. 제안된 슬라이딩 평면은 의란과 불확실성이 존재하더라도 PI 전류 제어기에 의해서 제어되는 공칭 시스템의 동특성을 가질 수 있다.

• 한국전자통신학회논문지
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• 제12권5호
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• pp.837-844
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• 2017

조석수조에서 수위를 조절하기 위한 위어는 자체에 부착된 2대의 전동실린더에 의해 상하로 이송된다. 이때 발생되는 좌 우 전동실린더의 이동거리 차는 위어의 불균형과 마찰을 일으키므로, 위어는 목표지점으로 이송될 수 없게 된다. 본 연구에서는 위어를 신속하고 정확하게 이송하기 위한 동기제어시스템이 구축된다. 교차결합구조에 기초한 이 동기제어시스템은 두 개의 I-PD제어기와 한 개의 진상보상기로 구성된다. 각 I-PD제어기는 전동실린더가 오버슈트와 입력포화를 발생시키지 않고 위치지령을 정확히 추종하도록, 그리고 진상보상기는 신속하고 안정적으로 동기가 되도록 설계된다. 끝으로 시뮬레이션을 통해 설계된 동기제어시스템이 동기오차의 제거에 효과적임을 나타낸다.