• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.21-32
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• 1996

The performance of the energy density control algorithm for controlling a broadband noise is evaluated in a one-dimensional enclosure. To avoid noncausality problem of a control filter, which often happens in a frequency domain optimization, analyses presented in this paper are undertaken in the time domain. This approach provides the form of the causally constrained optimal controller. Numerical results are presented to predict the performance of the active noise control system, and indicate that imp개ved global attenuation of the broadband noise can be achieved by minimizing the energy density, rather than the squared pressure. It is shown that minimizing the energy density at a single location yields global attenuation results that are comparable to minimizing the potential energy. Furthermore, unlike the squared pressure control, the energy density control does not demonstrate any dependence on the error sensor location for this one-dimensional field. A practical implementation of the energy-based control algorithm is presented. Results show that the energy density control can be implemented using the two sensor technique with a tolerable margin of performance degradation.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.1
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• pp.27-33
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• 2023

Recently, water shortages have occurred due to climate change, and the need for water management of agricultural water has increased due to the occurrence of algal blooms in reservoirs. Existing algae prevention is operated by putting many people on site and misses the optimal spraying time due to movement through boats. In order to solve this problem, it is necessary to block contamination in advance and move within time to uniformly spray complex microorganisms uniformly. Control drones are used for pesticide spraying and can be applied to algae prevention work by utilizing control drones. In this paper, basic research for the establishment of a marine control system was conducted for application to the reservoir environment, and as one of the results, the characteristics of a drone nozzle, a core technology that can be used for control drones, were calculated. In particular, it was found that the existing agricultural control drones had a disadvantage that the concentration was non-uniform within the suggested spraying interval, and to compensate for this, nozzle positioning and nozzle spraying uniformity were calculated. Based on the experimental results, we develop a core algorithm for establishing an algal bloom monitoring system in the reservoir environment and propose a precision control technology that can be used for marine control work in the future.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.52-52
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• 2022

Recently, PE (polyethylene) film has been used increasingly in com cultivation. However, PE films often cause soil and environment contamination. In order to reduce this problem, many researches have been carrying out studies on biodegradable films (BF) that are easily decomposed by soil microorganisms. Therefore, this study was conducted to determine which BF is optimal for growth and yield of com crops while also having the highest rates of film decomposition. BFs Farmsbio (Farm Hannong), Heulgro Film (Sejin Bio), Vonto Film (Eco-Hansung) as well as a selected PE film were used in this study. For the control, we used crops grown without any kind of mulching. Experimental fields were fertilized according to conventional cultivation methods, tilled, and then covered by either BF or PE. After 1 week, com (cv. MIBECK2ho) at the 3-leaf stage (16 days after seeding) was transplanted. Plant height was measured at 18 and 32 days after transplanting and heading stages. Yield components and yield were also measured at harvest. In addition, pH, EC, and decomposition and light transmittance levels of films were investigated during the experimental period. Daily average temperature, relative humidity and organic matter in soils were also measured during the experimental period. There was no significant difference in plant height, heading date, and silking between crops with BFs and PE, but the crops grown with BFs and PE films reached higher growth parameters in a shorter amount of time than the crops in the non-mulching control. Additionally, there were no significant differences in yield components such as length of ears, ear width, ear weight, and yield in crops that were grown using films or crops in the control plot. Light transmittance and decomposition levels of films generally increased with time after transplanting, and was highest in the Heulgro film than other BFs. Soil pH and organic matter in crops using BFs and PE films were significantly higher than in the control plot at 99 and 113 days after transplanting. In general, the EC contents in the control plot was lower than in crops using BFs and PE films. The average daily moisture in soil was higher when BFs and PE films were used than in the control plot. However, the daily average soil temperature was higher in crops using BFs and PE films than in the control plots at the beginning of the experimental period, but there was no consistent difference in soil temperature towards the later part of the experimental period. Therefore, the BFs used in this study were shown to be helpful without causing negative impacts on the growth and yield of com.

• Journal of Internet Computing and Services
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• v.11 no.3
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• pp.131-137
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• 2010

Today, many museums are changing their forms with ubiquitous environment. Unlike traditional museums providing only static text-based information attached to its corresponding artifacts to visitors, those ubiquitous museums provide not only artifacts' text information, but also many different forms of information such as sound or media through personal digital assistance or cell phones. However, these existing ubiquitous museums still provide each visitor only with artifact-centric information in very simple ways. Also this disadvantageous feature causes high gallery congestion problem resulting from providing a uniform path for every visitor. These limitations may be the biggest barrier to providing more various and useful information about artifacts to visitors through considering each visitor's preference. This paper propose a new optimal viewing path search algorithm to provide comfortable museum viewing for each visitor according to its preference. Also, a new congestion control method is developed to protect visitors from being put in some hot spots on their museum viewing, improving its comfort to a maximum.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.355-361
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• 2008

Stereo matching is one of the most active research areas in computer vision. In this paper, we propose a stereo matching scheme using genetic algorithm for object depth recognition. The proposed approach considers the matching environment as an optimization problem and finds the optimal solution by using an evolutionary strategy. Accordingly, genetic operators are adapted for the circumstances of stereo matching. An individual is a disparity set. Horizontal pixel line of image is considered as a chromosome. A cost function is composed of certain constraints which are commonly used in stereo matching. Since the cost function consists of intensity, similarity and disparity smoothness, the matching process is considered at the same time in each generation. The LoG(Laplacian of Gaussian) edge is extracted and used in the determination of the chromosome. We validate our approach with experimental results on stereo images.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.8
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• pp.889-897
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• 1999

This paper deals with a problem searching a target transfer function to meet the time-domain specifications for feedback system with given plant transfer function. For the Type I system, we first define three forms of transient response to unit step input, which are named by F, M, S-type. These are charaacterized as follows ; F-type has fast initial response and slow approach to the steady sate after reaching at 90% of the steady state value, S-type has slow initial response but fast approach to the steady state, and M-type is denoted by highly smooth response between F-type and S-type. Three prototypes corresponding to each form are proposed, time. For the order $n{\geq}4$, after determining admissible root structures of target characteristic polynomials empirically and expressing such polynomial coefficients by using special parameters ${\gamma}_i$ and $\epsilon$, the optimal prototypes that minimize the integral of the squared of the modified errors(ISME) have been obtained. Since the step responses of these prototypes have almost same wave forms irrespective to the order, the desired settling time or the rise time can be converted into the equibalent time constant $\tau$ and thus it is easy to obtain a target transfer function. It is shown through a design example that the present prototype is very useful for meeting the time-domain specifications and has been compared with different methods with a viewpoint of pertinence.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.85-91
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• 2014

Nowadays, Dynamic lighting control and management skills are studied and used. If the system which is to manage multiple intelligent spot applied ubiquitous service technology is built with decision making and used in the complex intelligent space like a apartment then will improve energy efficiency and provide comfortability in optimal conditions. To solve this problem distributed autonomous control middleware and energy management system which process data gathering by zigbee mesh network and search proper services to save energy by the existing state of things is necessary. In paper we designed DDLEMS (Distributed Dynamic Lighting Energy Management System) that is to service duplex communication embedded by software based home server platform to provide mobile services in the smart place and support decision making about energy saving to the best use of wireless censor node and controled network, energy display devices.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.5
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• pp.487-495
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• 2012

In this paper, a Smart Home Service Robot, McBot II, which performs mess-cleanup function etc. in house, is designed much more optimally than other service robots. It is newly developed in much more practical system than McBot I which we had developed two years ago. One characteristic attribute of mobile platforms equipped with a set of dependent wheels is their omni- directionality and the ability to realize complex translational and rotational trajectories for agile navigation in door. An accurate coordination of steering angle and spinning rate of each wheel is necessary for a consistent motion. This paper develops trajectory controller of 3-wheels omni-directional mobile robot using fuzzy azimuth estimator. A specialized anthropomorphic robot manipulator which can be attached to the housemaid robot McBot II, is developed in this paper. This built-in type manipulator consists of both arms with 4 DOF (Degree of Freedom) each and both hands with 3 DOF each. The robotic arm is optimally designed to satisfy both the minimum mechanical size and the maximum workspace. Minimum mass and length are required for the built-in cooperated-arms system. But that makes the workspace so small. This paper proposes optimal design method to overcome the problem by using neck joint to move the arms horizontally forward/backward and waist joint to move them vertically up/down. The robotic hand, which has two fingers and a thumb, is also optimally designed in task-based concept. Finally, the good performance of the developed McBot II is confirmed through live tests of the mess-cleanup task.

• KIEAE Journal
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• v.17 no.3
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• pp.119-124
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• 2017

Purpose: Groundwater heat pump (GWHP) system has high coefficient of performance than conventional air-source heat pump system and closed-loop type geothermal system. However, there is problem in long-term operation that groundwater raise at the diffusion well and reduced at the supply well. Therefore, it is necessary to accurately predict the groundwater flow, groundwater movement and control the groundwater level in the wells. In this research, in consideration of hydrogeological characteristic, groundwater level and groundwater movement were conducted analysis in order to develop the optimal design method of the two-well system using the pairing pipe. Method: For the optimum design of the two-well system, this research focused on the design method of the pairing pipe in the simulation model. Especially, in order to control the groundwater level in wells, pairing pipe between the supply well and diffusion well was developed and the groundwater level during the system operation was analyzed by the numerical simulation. Result: As the result of simulation, the groundwater level increased to -2.65m even in the condition of low hydraulic conductivity and high pumping flow rate. Consequently, it was found that the developed system can be operated stably.

• Journal of Information Processing Systems
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• v.5 no.1
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• pp.33-40
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• 2009

Ever since the network-based malicious code commonly known as a 'worm' surfaced in the early part of the 1980's, its prevalence has grown more and more. The RCS (Random Constant Spreading) worm has become a dominant, malicious virus in recent computer networking circles. The worm retards the availability of an overall network by exhausting resources such as CPU capacity, network peripherals and transfer bandwidth, causing damage to an uninfected system as well as an infected system. The generation and spreading cycle of these worms progress rapidly. The existing studies to counter malicious code have studied the Microscopic Model for detecting worm generation based on some specific pattern or sign of attack, thus preventing its spread by countering the worm directly on detection. However, due to zero-day threat actualization, rapid spreading of the RCS worm and reduction of survival time, securing a security model to ensure the survivability of the network became an urgent problem that the existing solution-oriented security measures did not address. This paper analyzes the recently studied efficient dynamic network. Essentially, this paper suggests a model that dynamically controls the RCS worm using the characteristics of Power-Law and depth distribution of the delivery node, which is commonly seen in preferential growth networks. Moreover, we suggest a model that dynamically controls the spread of the worm using information about the depth distribution of delivery. We also verified via simulation that the load for each node was minimized at an optimal depth to effectively restrain the spread of the worm.