• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.731-733
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• 2016

The primary goal of the line tracer is to accurately and quickly detect the movement up to the target position given by the sensor juhaengseon. It has been used in applications in various fields such as the current unmanned transport vehicles, laser cutting machine, autonomous mobile robots and unmanned driving is possible, and is held annually at various universities in the competition field with the possibility of great progress, depending on the application. However, there arises a large difference in running performance, depending on the hardware design and control. In this paper, improving the characteristics of the tracer line and characters to design a PID controller is to apply the point on ways of improving the properties of the system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.989-996
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• 2011

An understanding of the concentrated solar flux is critical for the analysis and design of solar-energy-utilization systems. The current work focuses on the development of an algorithm that uses the Monte Carlo ray-tracing method with excellent flexibility and expandability; this method considers both solar limb darkening and the surface slope error of reflectors, thereby analyzing the solar flux. A comparison of the modeling results with measurements at the solar furnace in Korea Institute of Energy Research (KIER) show good agreement within a measurement uncertainty of 10%. The model evaluates the concentration performance of the KIER solar furnace with a tracking accuracy of 2 mrad and a maximum attainable concentration ratio of 4400 sun. Flux variations according to measurement position and flux distributions depending on acceptance angles provide detailed information for the design of chemical reactors or secondary concentrators.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.258-265
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• 2017

At the early stage of the development of high speed propulsion systems, the designers suffer from the lack of both the quantity and the quality of test data. In that situation, the associated uncertainties could not be modeled as probabilistic distribution since probabilistic modelling requires large amount of data. In this paper, instead, the information provided by experts based on their experience and engineering knowledge was used to model uncertainty using the evidence theory. In designing the DCR(Dual Combustion Ramjet) engine, the combustion efficiencies, not well understood and little data existing, are assumed to have been provided by experts. And the uncertainties are quantified by Evidence theory. The quantified uncertainties are incorporated into the optimization. The design variables, area of inlet and area of combustor exit, have been found while satisfying reliability margins of thrust and thermal choking. The results show a reasonable design of the engine under the uncertain circumstances.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• Smart Media Journal
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• v.12 no.7
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• pp.9-17
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• 2023

Plant diseases and pests affect the growth of various plants, so it is very important to identify pests at an early stage. Although many machine learning (ML) models have already been used for the inspection and classification of plant pests, advances in deep learning (DL), a subset of machine learning, have led to many advances in this field of research. In this study, disease and pest inspection of abnormal crops and maturity classification were performed for normal crops using YOLOX detector and MobileNet classifier. Through this method, various plant pest features can be effectively extracted. For the experiment, image datasets of various resolutions related to strawberries, peppers, and tomatoes were prepared and used for plant pest classification. According to the experimental results, it was confirmed that the average test accuracy was 84% and the maturity classification accuracy was 83.91% in images with complex background conditions. This model was able to effectively detect 6 diseases of 3 plants and classify the maturity of each plant in natural conditions.

• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.190-196
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• 2023

This study was carried out to collect gas emitted from agricultural heaters using kerosene and to identify the emission concentration of carbon dioxide according to the age of agricultural heating machine. As a result of the linear regression analysis, the carbon dioxide emissions according to the year of agricultural heating machine are R² = 0.84, which follows y = 26.99x+721.98. Distributed analysis was classified into three groups according to the age of agricultural heating machine. As a result of the distributed analysis, it was 2.196×10^-13, which was smaller than the 0.05 probability set for the analysis, which means that there is a difference in at least one group. As a result, the age of the agriculture machine was divided into three groups and the difference between groups was tested. A statistical analysis result was derived that there was a difference in the emission concentration of carbon dioxide according to the age of agricultural heating machine. It is thought that it can be used to investigate greenhouse gas emissions by investigating the amount of carbon dioxide generated by agricultural heaters in the agricultural field of Korea.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.43-51
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• 2019

The aircraft vertical acceleration from the excitation of the road surface in the taxing mode is a main factor with a negative effect on the boarding quality of pilots and passengers. In this paper, we propose an appropriate control method to improve the boarding quality of the MR damper landing gear. The proposed control method is Skyhook Control Type 2, which feeds the aircraft vertical acceleration back in addition to the aircraft vertical velocity. Since Skyhook Control Type 2 factors the velocity and acceleration of the upper mass, it can be expected to exceed the control performance of the existing Skyhook Control that factors only the upper mass velocity. For the simulation, the bumper type road surface was selected as a ground surface, and the landing gear model constructed with RecurDyn and the controller designed with Simulink were co-simulated. The control effect of Skyhook Control Type 2 was verified by comparing and analyzing the RMS and maximum value of the upper mass acceleration according to the taxing speed and control method.

• Composites Research
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• v.27 no.4
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• pp.123-129
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• 2014

Ceramic matrix composites (CMCs) consist of such reinforcements as carbides, nitrides, borides and oxides, which have high melting points, low density, high modulus and high strength, for the purpose of increasing toughness. These materials are used for heat shielding systems for aerospace vehicles, high-temperature gas turbine combustion chambers, turbine blades, stator vane parts, etc. Oxide CMCs are used for the components of burner and flame holder and the high-temperature gas duct. CMCs are also applied to brake disks, which are subjected to severe thermal shock, and slide bearing parts under heavy loads. The research and development of the CMC are progressed for the strategic purpose in defense and energy industry; for instance, for aerospace applications in the U.S., and for hyper-speed aircraft, gas turbines, and atomic fissions in U.S., Japan, and Europe.

• Journal of Korea Spatial Information System Society
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• v.5 no.1 s.9
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• pp.83-89
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• 2003

The GIS which is analysis of the real world to construction of 3D virtual city develop s in rapid growth. 3D virtual city is simulated by use of a GIS, Computer graphics, virtual reality and Spatial database. In this paper 3D topographical basemap which have the geographic coordinate of world was constructed by digital map. And build the Cyber city with combining the building that have elevation and 3D topographical basemap. By using server/client system for the cyber city. 3D cyber city web service implemented. We proposed the hybrid base web service method rather than the image or vector base web service. By the spatial and attribute search in the 3D Cyber City, overcome the existing simple visibility of Web 3D technology, and exhibited development direction to the Web 3D GIS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1105-1116
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• 2008

Cognitive radio is one of the most effective techniques to improve the spectrum utilization efficiency. To implement the cognitive radio, spectrum sensing is considered as the key functionality because only counting on it, can the secondary users identify the spectrum holes and utilize them efficiently without causing interference to primary users. Generally, there are several spectrum sensing methods; the most common and simplest method is energy detection. However, the conventional energy detection has some disadvantages, which are caused by noise, especially, uncertain noise power leads to degradation of energy detector. In this paper, to solve this problem, we proposed sliding window-based energy detection method which can devide the frequency band of primary signal and noise using sliding window to estimate the power of primary user without the noise effect and achieve the better performance. It can calculate the energy of primary user only and can detect the primary signal. The simulation result shows that our proposed method outperforms conventional one.