Earticle

In this study, a response model of a beam structure was established through finite element analysis by analyzing the vibration response to external excitation. The vibration control performance of the beam was then evaluated by applying the narrow-band Fx-LMS algorithm for active structural control. The transfer function was obtained at the error sensor location when the structure was excited and the three-axis actuator was operated. The performance of the active control was investigated with 18 channels for error input and actuator output. When the equipment is exciting, the response of the error sensor is the primary path, and when the inertial 3-axis actuator operates, the response of the error sensor position is the secondary path, and the Fx-LMS algorithm is applied. The simulation was performed by changing the control parameters so that the response of the error sensor can satisfy the target performance. From the results of this study, the acceleration results over time showed about 70% vibration reduction after active control, and the average error value of the error sensor also decreased by about 68%. In addition, it was confirmed that real-time control of a system with 18 sensors and 18 actuators is possible even if the secondary path is configured in two orders.

In this study, an active vibration control experiment was conducted on a display manufacturing system weighing approximately 15 tons. Three pneumatic shakers were installed underneath the equipment to excite the entire structure at three different frequencies. On the top side of the equipment, four inertial-type electromagnetic actuators capable of generating forces in the x, y, and z directions were mounted, enabling 12 degrees of freedom to be controlled. At locations near the actuators, four tri-axial accelerometers were installed to obtain 12 error signals. Vibrations at three distinct frequencies induced by the pneumatic shakers were measured at these 12 locations using the accelerometers. Active vibration control was performed by driving the inertial actuators using a narrow-band Fx-LMS algorithm to reduce the measured error signals. As a result of the control, the vertical vibration at 24 Hz was successfully reduced by 10.95 dB.

조명제어 시스템은 전등 부하를 효율적으로 관리 및 제어하여 전력 에너지 절감 효과를 도모하는 시스템 이다. 특히 야외의 공원이나 아파트 단지 등 전등의 수가 많고 효율적인 모니터링이 필요한 곳에 필요한 시스템이 다. 최근에는 조명의 밝기와 색상을 제어하여 감성조명을 적용한 시스템 개발이 진행되고 있다. 본 연구에서는 LoRa 기반의 원격제어 기술을 적용한 조명 제어 시스템을 설계하였다. 제안한 시스템의 주목적은 설치된 조명의 상황을 모니터링하고 주변 환경에 따라 조명을 자율적으로 제어하는 데 있다. 본 연구에서 사용한 통신 모듈은 Murata LoRa이며 동작 주파수는 922.1 Mhz를 적용하여 노드 간의 통신을 구현하였다. 제안한 시스템은 야외 온 도와 습도를 실시간으로 측정하여 조명의 밝기 및 색상을 능동적으로 제어할 수 있도록 설계하였다. 실험을 통해 LoRa 기반 야외 조명 제어 시스템의 통신 신호 범위는 최대 120m까지 작동하는 것을 확인할 수 있었다.

A lighting control system is a system that efficiently manages and controls light loads to promote power and energy saving effects. In particular, it is a necessary system for places where there are many lights, such as outdoor parks or apartment complexes, and efficient monitoring is required. Recently, development of a system that applies emotional lighting by controlling the brightness and color of lighting is being developed. In this paper, a lighting control system using LoRa-based remote control technology was designed. The main purpose of the proposed system is to monitor the status of the installed lighting and autonomously control the lighting according to the surrounding environment. The communication module used in this study is Murata LoRa, and communication between nodes is implemented by applying an operating frequency of 922.1 Mhz. The proposed system is designed to actively control the brightness and color of lighting by measuring outdoor temperature and humidity in real time. Through experiments, it was confirmed that the communication signal range of the LoRa-based outdoor lighting control system operates up to 120m.

A kimchi container actively controlling CO2 concentration by timely flushing of CO2 gas was structured and tested in its capability and effectiveness because high CO2 concentration enhances the sensory flavor of the product. The inlet and outlet valves of CO2 gas were programmed to open and close allowing synchronous vent/CO2 flush according to the requirements of its dissolution in the contained kimchi. During the chilled storage, the headspace of container could be maintained at desired high CO2 concentration providing the preferred kimchi in sensory quality compared to control of the conventional container. However, there was no significant difference between the high CO2 container and control (container simply closed with air) in kimchi quality attributes of pH, titratable acidity, total viable bacterial count, Lactobacillus sp. count and Leuconostoc sp. count. The flow rate and time interval of CO2 flushing need to be adjusted considering the kimchi amount, headspace volume and ripening time. The designed system has potential to be applied in refrigerator appliances in homes and food service industry.

Objective To determine whether an active rehabilitation program that involves repetitive effortful muscle contractions, including core stability, balancing exercises, progressive resistance exercises, and running activities, after a sports hernia, is effective. Methods Forty soccer players with sports hernias were randomly divided into two equal groups: group A (active rehabilitation program) and group B (conventional treatment). The methods of assessment included a visual analog scale (VAS) and hip internal and external range of motion assessments. Group A received conventional treatment (heat, massage, transcutaneous electrical nerve stimulation, and mobilization) plus an active rehabilitation program, while group B received only conventional treatment. Three treatment sessions were given each week for 2 months. Evaluations were performed pre- and post-treatment. Results A decrease in VAS was seen in both groups at the end of treatment, 80.25% in group A and 41.93% in group B. The difference between the two groups was statistically significant (p=0.0001), whereas there were no statistical differences in internal and external rotation between the groups at the end of treatment (p>0.05). After treatment, an improvement in outcome measures of group A compared to group B (p=0.01) was seen. Thirteen patients in group A and only three patients in group B returned to sports activities without groin pain. Conclusion Active rehabilitation was effective for sports hernia management measured by a decrease in pain and the return to sports.

이 논문은 시스템 식별 기법을 이용하여 외팔보 진동제어 시스템의 수학적 모델을 구한 후 PID 제어기를 장착하여 효과적인 진동제어 결과를 제시하였다. 압전세라믹(piezo-ceramic)은 작동기로서 가장 기본적인 유연 구 조물의 형태인 외팔보의 진동을 억제하는데 사용되었으며 레이저 센서가 보의 굽힘 변위를 측정하는데 사용되었 다. 압전 세라믹의 입력 전압으로부터 레이저 감지기의 출력 전압까지의 전달함수를 계단입력에 대한 응답 실험데 이터에 시스템 식별 기법을 적용하여 구하였다. PID제어기는 산업현장에서 널리 사용되고 있으나, 적절한 이득 값 을 결정하는 것은 간단하지 않아, 본 연구에서는 Ziegler-Nichols 기법을 통해 PID 제어기를 튜닝하여 압전 세라 믹을 작동기로 사용하는 외팔보 시스템의 진동 제어에 적용하였고 시뮬레이션과 실험적 결과를 통하여 시스템식 별 기법을 통해 구한 수학적 모델의 유용성과 설계된 제어기의 효과적인 진동 제어 성능을 확인하였다.

In this paper first we obtained a mathematical model for a cantilever beam vibration control system with a piezoceramic actuator using system identification techniques and then implemented a PID controller for active vibration control. A piezoceramic is used as an actuator to control the vibration of a cantilever beam which has been used in many real structures, and a laser sensor is used to measure tip displacement of the cantilever beam in transverse motion. A transfer function from piezoceramic’s input voltage to laser sensor’s output voltage is obtained using system identification techniques utilizing experimental data from step response of the open-loop cantilever beam control system. The PID controller is tuned by Ziegler-Nichols technique and implemented to the beam control system. The result exhibits good performance in terms of vibration reduction, which validates the identification of the system and tuning of the PID controller.

controlling building vibration due to a seismic disturbance. The dynamic system is of a realistic four story steel moment resisting frame modeled as a lumped mass system to reduce the degrees of freedom. The feasibility to apply the active control with Kalman-filter is verified from the investigation of the controllability and the observability of the building system. As results, the responses of the controlled system were compared to those of the uncontrolled system. The effects of attaching the limited number of controllers at different locations were investigated. Also, the responses of the full state feedback control(LQ) and the system with Kalman-filter were compared to evaluate the capability of estimating the unmeasured state variables that the Kalman-filter was supposed to offer.

The purpose of this paper is to investigate the vibration phenomenon occurring in the structure such as a ship with the hemispherical substructure and operating at fixed frequency, and to suggest the active vibration control method using the Fx-LMS algorithm to reduce vibration amplification. In order to study the possibility of reducing vibration in the hemispherical structure, the active vibration control model was developed and a vibration control experimental device for the hemispherical structure was constructed. The narrowband Fx-LMS algorithm was developed to enable precise real-time control at a specific frequency, and the secondary path for dynamic control was modeled with two coefficients per frequency. The experimental device is equipped with three exciters, six 3-axis actuators, and six 3-axis error sensors, which can acquire 18 error sensor signals. Real-time secondary path tracking was possible with the secondary path consisting of two coefficients and the control algorithm, and effective vibration control performance was confirmed through this. And the experimental results of active vibration control of the exciter for three frequencies showed that the exciter vibration was reduced by a minimum of 63.7% and a maximum of 97.7%, which shows the possibility of reducing the vibration of the structure in real time using the proposed method.

해외 주요 도시에서 운영되고 있는 트램은 도시부의 교통혼잡과 대중교통의 수송분담율 감소 문제, 환경문제를 해결할 수 있는 대중교통 수단으로 인식되어 우리나라의 각 지방자치 단체에서 시스템 도입을 진행 중에 있다. 본 연구에서는 기존 신호운영 체계에서 트램을 효율적으로 운영하기 위한 능동식 트램 우선신호 전략을 개발하였다. 트램 우선신호를 수행하기 위한 시스템을 구성하고, 트램 정류장의 정차시간을 제어를 통해 트램의 교차로 무정차 통과를 구현하는 알고리즘을 개발하였으며, 대향방향의 트램차량을 고려하여 트램의 신호교차로 연속통행을 구현하였다. 또한 트램의 교차로 도착시간에 따라 정류장의 정차시간을 최소화하기 위한 능동식 우선신호 전략을 선택함으로서 신호제어 효과를 극대화 하였다. 개발된 신호제어전략을 평가하기 위해서 VISSIM 모형의 API 기능을 이용하여 트램 우선신호 제어전략을 구현하여 신호제어 효과를 분석한 결과, 트램차량의 신호교차로 정지수와 통행시간이 감소했음을 확인하였고, 일반차량도 트램 우선신호에 따른 지체증가가 거의 나타나지 않음을 확인하였다.

Recently, our local governments are conducting the introduction of tram system because it is recognized as an effective public transit that can solve a traffic jam in downtown, decreasing public transit share and environmental issues in world wide cities. We developed the Active Priority Control Strategy to efficiently operate a tram in our existing traffic signal system. This study organized the tram system for operating the Active Priority Signal Control, developed the algorithm that calculates a tram-stop dwell time in order to pass the downstream intersection without a stop. The dwell time is determined by arrival time at tram-stop, downstream signal time, and the location of a opposite tram, it can be reduced by choosing the optimal one among Signal Priority Controls. Using the VISSIM and VISVAP model, we conducted a simulation test for the city of Chang-won that it is expected to install a tram system. It showed that a developed signal control strategy is effective to prevent a tram's stop in intersections, to reduce a tram's travel time.

The dynamic characteristics of the structure must be understood in order to design an efficient active seismic controller. Evaluating the parameters with precision is very crucial not only for accomplishing a low cost controller, but for preventing the structural control system from unstable behavior. These characteristics of the structures can be estimated from the measured input-output data called the system identification. The purpose of the study is to evaluate the feasibility of the system identification method used in mechanical and electrical engineering applications to apply for the building structures subjected to seismic disturbance. The result of study that ARX model, ARMA model, ARMAX model can be suitable model to apply for building structure in the system identification.

The dynamic characteristics of the structure must be understood in order to design an efficient active seismic controller. Evaluating the parameters with precision is very crucial not only for accomplishing a low cost controller, but for preventing the structural control system from unstable behavior. These characteristics of the structures can be estimated from the measured input-output data called the system identification, and then the dynamic behavior of structure can be thoroughly analyzed though a computer simulation, which leads to the way to come up with an excellent controller. The purpose of the study is to evaluate the feasibility of the system identification method used in mechanical and electrical engineering applications to apply for the building structures subjected to seismic disturbance. The results show that the model behaves sensitively with respect to the lambda values. ARMA and ARMAX model showed relatively stable estimating performance against changes of the lambda values, and superior estimating performance under the same value of the lambda comparing to ARX. The conclusion is that the ARMAX model can be the most suitable one to apply for building structure in the system identification.

가새가 마찰면을 통해 에너지를 소산시키는 마찰가새(FSB)는 마찰력이 가새의 축저항력을 초과하기 전까지 탄성거동을 한다. 본 연구는 이런 FSB 거동을 바꾼 하이브리드 에너지 소산장치인 능동조임마찰가새(AFSB)를 제안한다. FSB는 마찰면에 능동적으로 조임력을 가하면 지진동을 보다 효율적으로 제어할 수 있는 AFSB로 변한다. 조임력은 컴퓨터 프로그램의 알고리즘을 통해 변동하며 제어된다. 해석결과에 의하면 AFSB는 FSB에 비해 효과적으로 에너지를 소산시켜 응답사이클이 지속될 수록 매우 효과적으로 구조물의 변위를 제어해준다. 즉, 논문 서두에 제안된 강도일정증분 알고리즘은 약진 및 중진의 지진동에 변위와 밑면전단력을 효과적으로 제어함을 확인하였다. 강진의 경우에 AFSB는 응답초기부터 미끄러지는 특성으로 인해 오버슈팅이 발생하여 이를 극복하기위해 최대변위를 제한하도록 알고리즘을 수정하고 결과를 확인하였다.

Structural bracing concept equipped with a new and efficient friction based energy dissipation device is referred to Friction Slip Brace (FSB) where the behavior of the brace components is elastic until the axial resistant force in the brace exceeds the friction force developed at the frictional interface of the device. In this study, the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction Slip Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The clamping action regulated by the developed algorithm is altered during the response of the building. The results indicate that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage. Providing predetermined constant incremental strengths to the building by AFSB members improves response by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations. However, early slippage of AFSB members cause overshooting of the response compared to FSB under large amplitude ground excitation. The operational algorithm of the AFSB members may be modified to prevent it.

The the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction Slip Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The results of Single-Degree-of Freedom(SDOF) structure have indicated that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage, and the problem has been taken cared by modifying the algorithm successfully shown in the previous publication in December 2016. It has also shown that providing predetermined constant incremental strengths to the building by AFSB members with the proposed algorithm for a SDOF structure has improved the responses by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations. In this study, the algorithm is tested on the Multiple-Degree-of-Freedom(MDOF) structure to verify the effectiveness of AFSB supplemented by the algorithm. A six story steel building which is the prototype building for part of the US-Japan Corporative Research Program is selected as an example building. The building is designed and modeled as an FSB and ASFB building, and subjected to a series of ground motions. The response envelopes of both buildings are obtained and compared to evaluate the design implication of AFSB applications.

Active front steering(AFS) system is able not only to vary steering ratio between steering wheel and tire wheel but also to steer front tires independently. In this paper, steering gear ratios and an active steering algorithm are proposed for the AFS system. Steering gear ratio is a function of vehicle speed and steering angle. Active steering is generated when the error of yaw-rate is larger than some threshold. To verify the performance of yaw stability, hardware-in-the-loop simulation system is made up of column type active steering system, driving display, steering effort reaction system and controller

An active suspension system has an external energy source, from which energy is constantly supplied to the system for continuous control of the vehicle's motion. There are some control strategies. In the study, the reduced-order active suspension control strategy via the singular perturbation technique is applied to the half car model which has 4 DOF. The performance of the hydraulic active suspension system utilizing this control strategy is investigated and compared with those of the systems with the full-order state feedback control and the sky-hook damping control. Their performances are compared through the computer simulation in the time and the frequency responses, respectively. In the transient response analysis, the C-language program is used, and Matlab program tool is used in the frequency response analysis. It is shown that the reduced-order control strategy yields almost the same performance as that of the full-order state feedback control, and gives better performance than that of the sky-hook damping control, especially in ride quality.

Most of the synchronization techniques belong to the master-slave (drive-response) system configurations in which the two chaotic systems are coupled in such a manner that the performance of the second (slave /response) system is influenced by the first (drive/master) system and the first system is not disturbed by the exertion of the second (slave / response) system. In this research paper, the synchronization problem of two widely used techniques, the Linear Active Control and Nonlinear Control Algorithms have been studied to achieve chaos synchronization of a new chaotic system. In this study, using the Linear Active Control and the Nonlinear Control algorithms and based on the Lyapunov Stability Theory, it has been shown that the two techniques have excellent transient performance and that analytically as well as graphically, the synchronization is asymptotically globally stable. Numerical simulations are furnished to show the efficiency and effectiveness of the two methods.