• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 1998년도 추계학술대회논문집:21세기에 대비한 지능형 통합항만관리
• /
• pp.175-180
• /
• 1998

In container crane system, the variation of cargo weight have effect on the travelling and sway control of load. For precise travelling and/or anti-sway control of crane system, the cargo weight should be measured and considered with control algorithm. But, and added attachment for measuring the cargo weight put restraint upon the control freedom for travelling and anti-sway. In this paper, we propose an estimation method for cargo weight in container crane system by using observation technique. First of all, we model the container crane system as a bilinear system and transform this model into linear system with external disturbance model. Second, we propose a generalized type - disturbance estimation observer and set a disturbance model, where, the cargo weight is related with the sway of load, and the sway is represented as a periodic external disturbance. Lastly, by using simulation we verify that the proposed algorithm of disturbance estimation observer is effective to estimate the cargo weight, and it will be used with anti-sway control algorithm.

• KSBB Journal
• /
• 제29권4호
• /
• pp.225-231
• /
• 2014

A microbial fuel cell (MFC) and bioelectrochemical systems are novel bioprocesses which employ exoelectrogenic biofilm on electrode as a biocatalyst for electricity generation and various useful chemical production. Previous reports show that electrogenic biofilms of MFCs are time varying systems and dynamically interactive with the electrically conductive media (carbon paper as terminal electron acceptor). It has been reported that maximum power point tracking (MPPT) method can automatically control load by algorithm so that increase power generation and columbic efficiency. In this study, we developed logic based control strategy for external load resistance by using $LabVIEW^{TM}$ which increases the power production with using flat-plate MFCs and MPPT circuit board. The flat-plate MFCs inoculated with anaerobic digester sludge were stabilized with fixed external resistance from $1000{\Omega}$ to $100{\Omega}$. Automatic load control with MPPT started load from $52{\Omega}$ during 120 hours of operation. MPPT control strategy increased approximately 2.7 times of power production and power density (1.95 mW and $13.02mW/m^3$) compared to the initial values before application of MPPT (0.72 mW and $4.79mW/m^3$).

• 한국정밀공학회지
• /
• 제18권10호
• /
• pp.45-52
• /
• 2001

This paper presents a study on the position tracking control of a robot system on the uncertain elastic base. The elastic bathe is a nonholonomic system but it can be changed into holonomic system, which is much easier to analyze, by modeling an elastic base as a virtual robot that has passive joints. Also, Jacobian operators, which represent the overall robot system including base movement, are defined and applied to the changed model. However, because base movements are not known, the exact Jacobian operators can＇t be estimated. The control algorithm proposed is that uses only Jacobians of a real robot as approximate Jacobian operators. Therefore the approximate Jacobian operators compensate the measured errors from external sensors. The proposed control strategy is evaluated by the simulation and experiment of a single-axis robot system on the elastic base.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.1212-1217
• /
• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• 제어로봇시스템학회논문지
• /
• 제3권6호
• /
• pp.555-562
• /
• 1997

With only the classical PID controller applied to control of a DC motor, good (target) performance characteristic of the controller can be obtained if all the model parameters of DC motor and operating conditions such as external load torque, disturbance, etc. are known exactly. However, in case when some of system parameters or operating conditions are uncertain or unknown, the fixed PID controller does not guarantee good performance, which is assumed with precisely known system parameters and operating conditions. In view of this and the robustness enhancement of DC motor control system, we propose a PID learning controller which consists of a set of learning rules for PID gain tuning and learning of an auxiliary input. The proposed PID learning controller is shown to drive the state of uncertain DC motor system with unknown system parameters and external load torque to the desired one world wide asymptotically. Computer simulation and experimental results are given to demonstrate the effectiveness of the proposed PID learning controller, thereby showing its superiority to the conventional fixed PID controller.

• 설비공학논문집
• /
• 제27권8호
• /
• pp.432-439
• /
• 2015

Current building procedures seek to minimize external air supplies to reduce the energy consumption of air conditioning, resulting in a high dependency on mechanical ventilation. We therefore studied an economizer-cycle system, whereby the introduction of external air saves energy. We analyzed different economizer-control methods, addressing mixed-air temperatures and outdoor-air fractions according to outdoor-air temperatures; also, we analyzed the energy consumption of the three economizer-cycle control types using detailed EnergyPlus simulation modeling. A differential enthalpy control method showed a lower energy consumption range from 5.8% to 6.2% than that of other methods during the simulated period. A differential dry-bulb control method showed a 12.7% lower energy consumption than the no-economizer method in the intermediate period, but also showed 7.1% more energy consumption during the summer period. When latent heat was not removed due to high summer humidity, we found a significant level of resultant energy consumption.

• 한국소음진동공학회논문집
• /
• 제25권10호
• /
• pp.707-713
• /
• 2015

This paper proposes experimental results for control performance deterioration of a piezoelectric actuator under high temperature conditions due to external heat environment. In this work, a heat environment from 30 ℃ to 190 ℃ is established by a heat chamber which is capable of high temperature of heat environment. Inside the heat chamber, an experimental apparatus consisting of the stack type of piezoelectric actuator, laser sensor, gap sensor and temperature sensor is established. After evaluating temperature dependent blocking force, displacement and time response of a piezoelectric actuator inside the heat chamber, tracking control performances are evaluated under various temperature conditions via proportional-integral-derivative(PID) feedback controller. The desired position trajectory has a sinusoidal wave form with a fixed frequency. Control performances are experimentally evaluated at both room temperature and high temperature and presented in time domain.

• 센서학회지
• /
• 제28권1호
• /
• pp.64-70
• /
• 2019

Wireless sensors have been developed in numerous ways for enhancing the convenience of installation, management and maintenance of sensors. Energy harvesting wireless sensors, which can collect energy from the external environment for permanent usage without the need of recharging and exchanging batteries, have been developed and employed used in Internet of Things and at various industrial sites. Energy harvesting wireless sensors are significantly affected by the sensor lifespan to sudden variation in the external environment. Furthermore, reduction in the sensor operating timespan can greatly affect the characteristics of the devices connected through a network. In this paper, a system performance index is proposed that can comprehensively evaluate the lifespan of a solar cell wireless sensor, determine the characteristics of devices connected to the associated network, and recommend dynamic power distribution control for improving the system performance index. Improvement in the system performance index was verified by applying the proposed dynamic power distribution control to an air conditioner network system using a solar cell wireless sensor. Obtained results corroborate that the dynamic power distribution control can extend the lifespan of the incorporated wireless sensor and reduce the air conditioner's power consumption.

• 대한안전경영과학회지
• /
• 제26권1호
• /
• pp.15-24
• /
• 2024

The purpose of this study is to improve the stack effect of the staircase and the failure to take into account the opening of the outside door of the staircase, which are the disadvantages of the existing smoke control only vestibule. As a result of the study, the new vestibule and the staircase simultaneous smoke control are equipped with an exhaust flap damper with an effective opening area of about 0.25 m² in the upper part of the staircase, and a ventilator-type air supply fan of about 5 m³/s in the lower part, and take measures to prevent overpressure in the staircase. If you use the new simultaneous smoke control method of the vestibule and staircase, you can achieve the following effects. First, it is possible to open the external entrance door. Second, it can reduce the stack effect. Third, the staircase door closes automatically without fail. And a new method of preventing overpressure was proposed for the vestibule.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제34권3호
• /
• pp.325-354
• /
• 2020

수학 학업성취도에 영향을 미치는 요인들은 매우 다양하며, 그 요인들이 미치는 영향 또한 복합적으로 일어난다. 수학 학업성취도에 영향을 미치는 요인들은 끊임없이 변화하고 발전하기 때문에 학습자들의 성장을 예측하고 분석하는 종단연구가 필요하다. 본 연구는 서울교육종단연구의 2013년도(중학교 1학년)부터 2017년(고등학교 2학년)까지의 종단자료를 활용하여 내적요인(자아개념, 자기통제, 삶의 만족에 대한 자기평가), 외적요인(학교풍토, 자녀에 대한 보호자의 관심, 보호자의 학습조력)의 변화패턴을 알아보고 내·외적요인이 수학 학업성취도에 어떠한 영향을 미치는지 살펴보았다. 수학 학업성취도를 분석한 결과, 중학교 1학년부터 중학교 2학년까지의 수학 학업성취도는 변화가 없는 것으로 나타났으며, 중학교 2학년부터 고등학교 1학년까지는 꾸준히 증가하다가 고등학교 2학년 때는 소폭 하향하는 것으로 나타났다. 내적요인인 자아개념과 자기통제는 중학교 1학년부터 중학교 2학년까지는 소폭 떨어지다가 고등학교 1학년까지는 소폭 증가하고 고등학교 2학년에는 소폭 떨어지는 것으로 나타났으며, 삶의 만족에 대한 자기평가는 중학교 1학년부터 고등학교 2학년까지의 기간 동안 소폭 떨어지는 것으로 나타났다. 외적요인 중 학교풍토는 중학교 1학년부터 중학교 2학년까지는 소폭 떨어지는 것으로 나타났으며, 고등학교 1학년까지는 증가하다가 고등학교 2학년에는 그 값이 유지되는 것으로 나타났다. 자녀에 대한 보호자의 관심은 중학교 1학년 때의 값이 고등학교 2학년까지 유지되는 것으로 나타났으며, 보호자의 학습조력은 중학교 1학년부터 지속적으로 감소하는 것으로 나타났다. 수학 학업성취도에 대한 영향을 알아보기 위해 임의 기울기 모델(Random Slope Model)을 시행한 결과 내적요인인 자아개념 및 자기통제, 그리고 외적요인인 학교풍토가 수학 학업성취도의 변화에 영향을 미치는 것으로 나타났다.