• 제어로봇시스템학회논문지
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• 제11권11호
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• pp.963-969
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• 2005

An advanced method of Relaxed Static Stability (RSS) is utilized for improving the aerodynamic performance of modem version supersonic jet fighter aircraft. The flight control system utilizes RSS criteria in both longitudinal and lateral-directional axes to achieve performance enhancements and improve stability. The T-50 advanced trainer employs the RSS concept in order to improve the aerodynamic performance and the flight control law in order to guarantee aircraft stability, The T-50 longitudinal control laws employ the dynamic inversion and proportional-plus-integral control method. This paper details the design process of developing longitudinal control laws for the RSS aircraft, utilizing the requirement of MIL-F-8785C. In addition, This paper addresses the analysis of aircraft characteristics such as damping, natural frequency, gain and phase margin about state variables for longitudinal inner loop feedback design.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.664-669
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• 1992

In this paper, we present a DSP-based high dynamic performance torque control scheme of variable reluctance motors(VRM's) for DD(Direct Drive) robots via function inversion technique. The VRM with our controller behaves like DC motors, and hence developed torque tracks given torque command accurately with no torque ripples. Furthermore, our torque control algorithm ensures the production of maximum constant torque under maximum current limitation, minimizes power loss in each phase resistance, and takes magnetic saturation effect into account. Also, since our control algorithm is represented in the form of look-up table, it can be easily implemented with simple digital circuits and this tabular design method is computationally more accurate and simpler compared to the prior methods.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1218-1225
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• 2008

This paper presents the design of a neural network based adaptive control for missile is presented. The application model is Exocet MM40, which is derived from missile DATCOM database. Acceleration of missile by tail Fin control cannot be controllable by DMI (Dynamic Model Inversion) directly because it is non-minimum phase system. So, the inner loop consists of DMI and NN (Neural Network) and the outer loop consists of PI controller. In order to satisfy the performances only with PI controller, it is necessary to do some additional process such as gain tuning and scheduling. In this paper, all flight area would be covered by just one PI gains without tuning and scheduling by applying mixture control technique of conventional controller and NN to the outer loop. Also, the simulation model is designed by considering non-minimum phase system and compared the performances to distinguish the validity of control law with conventional PI controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1505-1508
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• 2008

One of the important functions of prosthetic foot is the foot inversion-eversion which is so important when walking on uneven surfaces. The aim of our study was to evaluate the effect of foot eversion angle especially on knee and ankle joint for transtibial amputees by motion analysis. The experimental data were collected from three transtibial amputees and then ten healthy individuals. To simulate walking on side sloping ground, we used custom-made slope (5, 10, 15 degrees). Motion analysis was performed by 3-dimensional motion analyzer for 6 dynamic prosthetic feet. The results showed that knee abduction moments of amputated leg were decreased but those of sound leg were mainly increased as foot eversion angle increased. And ankle abduction moments of sound leg were inconsistent in magnitude and tendency between control and experimental group. Therefore foot eversioncharacteristics should be considered to develop advanced prosthetic foot.

• Smart Structures and Systems
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• 제21권2호
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• pp.163-170
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• 2018

The dynamic response of a finite length thermo-piezoelectric rod with variable material properties is investigated in the context of the fractional order theory of thermoelasticity. The rod is subjected to a moving heat source and fixed at both ends. The governing equations are formulated and then solved by means of Laplace transform together with its numerical inversion. The results of the non-dimensional temperature, displacement and stress in the rod are obtained and illustrated graphically. Meanwhile, the effects of the fractional order parameter, the velocity of heat source and the variable material properties on the variations of the considered variables are presented, and the results show that they significantly influence the variations of the considered variables.

• 한국항공운항학회지
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• 제21권3호
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• pp.1-8
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• 2013

An application of adaptive flight controller is required for the non-linear and high uncertain system that configuration of tiltrotor aircraft is dramatically changed from rotary wing mode to fixed wing mode. In this paper, the applicable adaptive controller for the tiltrotor aircraft was designed using Neural Networks and DMI (Dynamic Model Inversion). The performance of the SCAS (Stability and Control Augmentation System) was simulated against manned military specification, using the fullscale model of 'Smart UAV(Unmanned Aerial Vehicle)' developed by Korea Aerospace Research Institute. And Neural Networks based adaptive controller was verified through its whole operating envelope using the established HQ (Handling Quality) criteria.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 2003년도 제22회 동계학술발표회 논문집
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• pp.173-190
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• 2003

수요예측은 국가와 기업의 전략수립과 효율적인 자원활용에 있어서 필수적인 사전기획요소이다. 본 논문은 이산선택모델과 확산모델을 복합적으로 고려하여 다세대 제품의 수요를 예측하였다. 이산선택모델은 정적인 관점에서 소비자들의 제품에 대한 평가를 분석하는 모델이다. 본 논문에서는 이러한 이산선택모델에 수요의 동적인 변화양상을 고려할 수 있는 확산모델을 결합하였다. 실증분석으로서 1999년에서 2005년까지의 세계 DRAM시장 수요를 예측하였다. 또한, DRAM의 가격과 기억용량에 대해 '무어의 법칙' 과 '학습곡선'을 각각 적용한 기술예측을 시도하였으며, 이를 바탕으로 보다 정교한 예측모델을 전개하였다. 제시된 모델은 산업수준의 자료를 이용하였으므로, 이산선택모델을 inversion 하여 분석을 시도하였다. 이를 통해 기존세대의 DRAM 제품에 대한 수요뿐만 아니라, 새로운 세대의 DRAM 제품에 대한 수요를 비교적 정확히 예측할 수 있었다.

• Membrane and Water Treatment
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• 제8권1호
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• pp.51-71
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• 2017

Antimicrobial polyethersulfone ultrafiltration membranes containing zerovalent iron ($Fe^0$) and magnetite ($Fe_3O_4$) nanoparticles were synthesized via phase inversion method using polyethersulfone (PES) as membrane material and nano-iron as nanoparticle materials. Zerovalent iron nanoparticles (nZVI) were prepared by the reduction of iron ions with borohydride applying an inert atmosphere by using $N_2$ gases. The magnetite nanoparticles (nMag) were prepared via co-precipitation method by adding a base to an aqueous mixture of $Fe^{3+}$ and $Fe^{2+}$ salts. The synthesized nanoparticles were characterized by scanning electron microscopy, X-ray powder diffraction, and dynamic light scattering analysis. Moreover, the properties of the synthesized membranes were characterized by scanning electron microscopy energy dispersive X-ray spectroscopy and atomic force microscopy. The PES membranes containing the nZVI or nMag were examined for antimicrobial characteristics. Moreover, amount of iron run away from the PES composite membranes during the dead-end filtration were tested. The results showed that the permeation flux of the composite membranes was higher than the pristine PES membrane. The membranes containing nano-iron showed good antibacterial activity against gram-negative bacteria (Escherichia coli). The composite membranes can be successfully used for the domestic wastewater filtration to reduce membrane biofouling.

• 한국지반공학회논문집
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• 제38권8호
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• pp.17-27
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• 2022

김해평야 퇴적층의 동적 특성을 결정하기 위해 6개의 위치에서 상시미동 수평-수직비(HVSR)법으로 지반 고유진동수(f₀)를 도출하고 High frequency f-k방법과 Modified Spatial Autocorrelation 방법을 적용하여 상시미동 기반 표면파 분석을 수행하였다. 레일리파 분산곡선과 지반 고유진동수를 바탕으로 역해석을 실시하여 전단파 속도 주상도를 도출하였다. 분석 결과에 의하면 김해평야 퇴적층 지역은 1hz 이상의 진동수 대역에서 상당한 규모의 지반운동 증폭이 예상된다. 천부 퇴적층은 대체로 200m/s 내외의 전단파 속도를 보이고 60m~100m 사이의 깊이에서 기반암이 존재할 것으로 추정되며, 다수의 위치에서 천부 퇴적층과 기반암 사이에 V_s=400m/s 가량의 하성 퇴적층이 존재하는 것으로 나타났다. 역해석 결과를 바탕으로 김해평야 퇴적층의 전단파 속도-깊이 모델을 도출하였으며, 본 연구에 따르면 김해평야 퇴적층 지역에서 내진설계일반(KDS 17 10 00)의 S6지반에 해당하는 위치의 면적은 상당할 것으로 예상된다.

• 한국전산구조공학회논문집
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• 제36권3호
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• pp.203-211
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• 2023

층상 반무한체에서의 확률론적 완전파형역산을 위한 Markov chain Monte Carlo (MCMC) 모사 기법을 정식화한다. Thin-layer method를 사용하여 조화 수직 하중이 작용하는 층상 반무한체의 지표면에서 추정된 동적 응답과 관측 데이터와의 차이 및 모델 변수의 사전 정보와의 차이를 최소화하도록 목적함수와 모델 변수의 사후 확률밀도함수를 정의한다. 목적함수의 기울기에 기반하여 MCMC 표본을 제안하기 위한 분포함수와 이를 수락 또는 거절할지 결정하는 수락함수를 결정한다. 기본 진동모드 뿐만이 아니라 고차 진동모드가 우세한 경우를 포함하여 다양한 층상 반무한체의 전단파 속도 추정에 제안된 MCMC 모사 기법을 적용하고 그 정확성을 검증한다. 제안된 확률론적 완전파형역산을 위한 MCMC 모사 기법은 층상 반무한체의 전단파 속도와 같은 재료 특성의 확률적 특성을 추정하는 데 적합함을 확인할 수 있다.