• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.867-872
• /
• 2002

A high intensity acoustic test facility is constructed at Korea Aerospace Research Institute (KARI) by 2003. The reverberant chamber of the facility has a volume of 1,228 cubic meters and shall provide an acoustic environment of 152 dB over the frequency range of 25 Hz to 10,000 Hz. The facility consists of a large scaled reverberant chamber, acoustic power generation systems, gases nitrogen supply systems, and acoustic control systems. This paper describes how the basic parameters of a chamber and power generation systems are controlled to meet the requirement of the test. The volume of a reverberant chamber is controlled by the size of test objects and the reverberant characteristics of a chamber. The capacity of acoustic power generation systems is determined by the energy absorption of a chamber and the efficiency of acoustic modulators. Simple math is employed to calculate the required power of acoustic modulators. Moreover, the paper explains how the distribution of sound pressure level at low frequency is checked by analytical and numerical methods.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.6_2
• /
• pp.1007-1014
• /
• 2020

IMO(International Maritime Organization) continues to strengthen environmental regulations on exhaust gases such as CO2, NOx, SOx. As for sulfur oxides, from 1 January 2020, all ships on international voyages must use fuel with a sulfur content of 0.5% or less. Or, it is obligatory to use an exhaust gas treatment device that has the same effect. Shipping companies are using low-sulfur oil, replacing them with LNG fuel, or installing scrubbers that suppress sulfur oxide emissions. In the case of ships using bunker C oil, the load on the engine is lower when entering and departing, so the exhaust gas pressure is lowered and the scrubber cannot be properly utilized. Therefore, diesel oil with low sulfur content is used when entering and leaving the coast. When diesel oil is used, exhaust gas is directly discharged through the control system and piping system, and when bunker C oil is used, sulfur oxides are reduced by scrubbers through other control systems and piping systems to discharge exhaust gas. Accordingly, a company has developed a system called a three-way damper valve that can control exhaust gas emissions while integrating these two control systems and piping systems into one. In this study, the control characteristics of the integrated exhaust gas control system and structural safety against external loads in a high-temperature exhaust gas environment were reviewed.

• Journal of Environmental Policy
• /
• v.6 no.3
• /
• pp.1-31
• /
• 2007

The Integrated Pollution Prevention and Control(IPPC) has attracted western developed countries for their idealistic environmental prevention concept which corresponds to the principal of Industrial Ecology. Specially the United Kingdom has been interested in those topics earlier than other countries and carried out environmental prevention polices since 1970's. As a result of these efforts, United Kingdom gave effects EU on developing European IPPC directives. The United Kingdom recognized the importance of the integrated pollution control through the report of Royal Commission on Environmental Pollution(RCEP) in 1976. Further, the United Kingdom developed the report and resulted the Integrated Pollution Control Directives under Environmental Protection Law in 1990. In the process of the legislation, it established and developed the concept of Best Practicable Environmental Option(BPEO) for the regulations, administrative systems, and environmental control. These efforts of the United Kingdom has implications for South Korean policies in adopting Integrated Pollution Prevention and Control system. Thus, this study examines IPPC directives to broaden the understanding of the system and develop policies.

• 제어로봇시스템학회:학술대회논문집
• /
• 1995.10a
• /
• pp.472-475
• /
• 1995

In this paper, we investigate so-called the falling cat problem. It is well known that a cat, when released from an upside down configuration starting from rest, is able to land on her feet without violating angular momentum conservation. This has being an interesting problem for engineers for a long time. We consider a model of a falling cat as connected two rigid columns, which is a nonholonomic system. We design the controller for it, using time- state control form of the model and exact linearization technique. Finally, we test the controller thorough simulation on the model of a falling cat.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.19 no.4
• /
• pp.203-210
• /
• 2024

The automotive industry is transitioning from traditional internal combustion engines to systems powered by motors, batteries, and various electronic control units. Central to this shift is the micro-controller unit, which processes data from various sensors for real-time environmental awareness and control. This paper explores using non-contact magnetic sensors for sensing vehicle inclination as part of a digital twin implementation. Unlike optical or contact sensors, non-contact magnetic sensors offer robust performance in challenging environments, providing consistent and reliable data under varying conditions. To optimize real-time data processing, we propose a double buffer structure to enhance digital signal processing performance in embedded systems. Experiments using a custom sensor-integrated board demonstrate that the double buffer structure with direct memory access-enabled serial peripheral interface significantly reduces data processing time and improves noise reduction filtering. Our results show that the proposed system can greatly enhance the reliability and accuracy of sensor data, crucial for real-time vehicle control systems. In particular, by using the double buffer structure proposed in this paper, it was possible to secure 8.27 times more data compared to raw data, despite performing additional filtering. The techniques outlined have potential applications in various fields, offering enhanced monitoring and optimization capabilities, thus paving the way for more advanced and efficient vehicle control technologies.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.2
• /
• pp.191-199
• /
• 2006

Animal feedstuff handling is one of the major fugitive dust sources in the port of Incheon. For the effective control of fugitive dusts emitting from the port of Incheon, dust control facilities with bag filter systems should be designed properly considering the characteristic of the fugitive dusts including those from animal feedstuffs. The ultimate goal of this study is thus to develop the optimum fugitive dust control system which will be applicable for the renovation of the port. As the first step to achieve this longstanding goal, filtration characteristics of soybean shell, the largest dust sources in the port, were investigated with the specially designed filter testing apparatus for this study. The variables tested for the experiments included filter materials, dust concentrations, relative humidities, and filtration velocities. Also, the filtration characteristics of the other animal feedstuffs such as sunflower seed shell, tapioca, and palm shell were investigated to determine $K_2$ as a function of filtration velocity. The information on $K_2$ will be used to design the optimum bag filter systems for animal feedstuffs handling in the port.

• Earthquakes and Structures
• /
• v.11 no.6
• /
• pp.943-966
• /
• 2016

Recently, magnetorheological elastomer (MRE) material and its devices have been developed and attracted a good deal of attention for their potentials in vibration control. Among them, a highly adaptive base isolator based on MRE was designed, fabricated and tested for real-time adaptive control of base isolated structures against a suite of earthquakes. To perfectly take advantage of this new device, an accurate and robust model should be built to characterize its nonlinearity and hysteresis for its application in structural control. This paper first proposes a novel hysteresis model, in which a nonlinear hyperbolic sine function spring is used to portray the strain stiffening phenomenon and a Voigt component is incorporated in parallel to describe the solid-material behaviours. Then the fruit fly optimization algorithm (FFOA) is employed for model parameter identification using testing data of shear force, displacement and velocity obtained from different loading conditions. The relationships between model parameters and applied current are also explored to obtain a current-dependent generalized model for the control application. Based on the proposed model of MRE base isolator, a second-order sliding mode controller is designed and applied to the device to provide a real-time feedback control of smart structures. The performance of the proposed technique is evaluated in simulation through utilizing a three-storey benchmark building model under four benchmark earthquake excitations. The results verify the effectiveness of the proposed current-dependent model and corresponding controller for semi-active control of MRE base isolator incorporated smart structures.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.12
• /
• pp.1184-1191
• /
• 2009

Energy harvesting from environment can make the energy constrained systems such as sensor networks to sustain their lifetimes. However, environmental energy is highly variable with time, location, and other factors. Unlike the existing solutions, we solved this problem by allowing the sensor nodes with mobilizer to move in search of energy and recharge from remote energy station. In this paper we present and analyze a new harvesting aware framework for mobile sensor networks with remote energy station. The framework consists of energy model, motion control system and data transfer protocol. Among them, the objective of our data transfer protocol is to route a data packet geographically towards the target region and at the same time balance the residual energy and the link connectivity on nodes with energy harvesting. Our results along with simulation can be used for further studies and provide certain guideline for realistic development of such systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.1
• /
• pp.104-112
• /
• 2003

This paper introduces a thruster attitude control system for the KSR-III and addresses system configuration, design condition for several components and development systems. These systems were confirmed through environmental tests, compatibility tests with other sub-systems and are planned to launch by this year. After the launch test, it can be redesigned for optimal systems using post-analysis.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.1086-1088
• /
• 1993

A robust fuzzy self-organizing controller(SOC) is proposed for an environmental temperature chamber. Although fuzzy SOC can improve the performance of nonlinear system, the controller is ineffective to solve the performance degradation owing to the time varying factors. In this paper, we construct the fuzzy SOC with a predictive scheme based on the 386PC. The usefulness of the proposed scheme is shown through the comparison of the PI controller and the fuzzy controller.