• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.1-7
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• 2016

An uninterruptible power supply (UPS) allows small companies and domestic users to cope with power outages; but existing designs lack flexibility of control and require expensive battery maintenance, with a cost proportional to the outage compensation time. We combine a compact synchronous generator with a battery, with 10% of the capacity that would otherwise be required, to obtain a UPS with reduced maintenance costs for the same performance. Any UPS must respond immediately to a power loss, and our uninterruptible generator supply (UGS) is therefore built around real-time scheduling of its internal operations; this also makes it suitable for integration into the industrial gateway. The UGS is based on a real-time operating system, with an integrated wireless module providing connectivity to a web server, for monitoring and management, which can be performed remotely on a mobile device.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.400-403
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• 2005

The sonar sensors can be divided into a piezo type and an electrostatic type according to a principle of an operating system. The electrostatic type of a sonar sensor is used for map building in this paper. If we know the characteristics of sonar sensor, we can derive the ultrasonic pressure equation from an acoustics theory. We, therefore, developed Ultrasonic Pressure Probabilistic Model (UPPM) to consider the sound pressure in the probability updating process. In this paper, we found that the quality of the resulting probability map is considerably improved, through combining the UPPM with the grid-based mapping algorithm.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.437-438
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• 2019

본 논문에서는 ROS(Robot Operating System)기반으로한 로봇(Robot)에 레이저 거리 센서(LiDAR)를 설치하여 SLAM(Simultaneous Localization and Mapping : 동시적 위치 추적 지도 작성)기법으로 맵 정보를 습득하고, 저장하여 이를 기반으로 장애물과 건물의 실내 복도 안전하고 정확하게 순찰 할 수 있도록 하였다. 또한, 순찰 로봇(Robot)에 장착된 Raspberry카메라와 OpenCV 영상인식 기술을 이용하여 실시간 영상으로 실내 복도를 순찰하면서 사전에 설정된 특이사항이 있을 시 발견하고 기록하도록 시스템을 개발하였다.

• Industrial Engineering and Management Systems
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• v.15 no.2
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• pp.131-142
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• 2016

We consider a multi-server queueing system without buffer and with two types of customers as a model of operation of a mobile network cell. Customers arrive at the system in the marked Markovian arrival flow. The service times of customers are exponentially distributed with parameters depending on the type of customer. A part of the available servers is reserved exclusively for service of first type customers. Customers who do not receive service upon arrival, can make repeated attempts. The system operation is influenced by random factors, leading to a change of the system parameters, including the total number of servers and the number of reserved servers. The behavior of the system is described by the multi-dimensional Markov chain. The generator of this Markov chain is constructed and the ergodicity condition is derived. Formulas for computation of the main performance measures of the system based on the stationary distribution of the Markov chain are derived. Numerical examples are presented.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.402-410
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• 2019

Local area festivals have grown on a scale for the past 20 years, but have suffered ups and downs. Through the trial and error of the festival operation, problems such as prediction of the number of visitors, planning of event scale, calculation and expansion of sales volume, and management of various participants in the duration were highlighted. To solve, this study designed and developed a mobile payment system and festival operation management system for local scale festivals as a platform operating system of web and app combined. The results of this study presents four basic functions. It includes ticketing management, attendance identification and entrance control, charge of festival currency and use of payments, real-time provision and management of related information, and performance reporting for each role. It was applied to local festivals in practice as to enable local shop owners to participate in advertisements or sponsorships and confirmed their contribution to local commercial market and the revitalization of festivals through this system.

• Journal of The Korean Association of Information Education
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• v.10 no.2
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• pp.273-280
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• 2006

Most homepages of schools are available to publicize activities of education, to load educational materials efficiently. But we can't use current homepages of schools in making characteristic information or sharing educational resources. In this study, this CUBE system with RSS and mobile phone was designed and embodied for sharing characteristic educational activities and works in schools. Currently, CUBE is being under experimental test in elementry schools at Sancheong area, and instructors and students are operating CUBE for sharing education activities and making community in this system,.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.87-95
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• 1997

A chemical heat pump based on the reversible reactions between metal chlorides and ammonia gas is attractive alternative to compression system and liquid absorption systems in cooling and refrigerating fields. The advantages of chemical heat pump are no regulatory constants due to CFC refrigerants, utilization of gas, industrial waste heat, electricity, fuel oil etc. as heat sources and wide applications to energy storage system, large-scale energy managements for industrial process. The scale-up of chemical heat pump from laboratory prototype to pilot plants necessitates the interpretation of system performance and evaluation of dynamic behavior in the chemical reactor. This study contains the prediction of performance of chemical refrigerator according to operating condition, the dynamic simulations through reactor modelling, which is used for the calculation of reactive medium temperature and the conversion variation with reactor cooling temperature, and the effect survey of block parameters on the power of refrigerator.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.71-78
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• 2022

Electronic measuring devices have an important role in agricultural projects and in various fields. Electronic measuring devices play a vital role in controlling and saving soil information. They are designed to measure the temperature, acidity and moisture of the soil. In this paper, a new methodology to manage irrigation and soil fertility using an electronic system is proposed. This is designed to operate the electronic irrigation and adds inorganic fertilizers automatically. This paper also explains the concept of remote management and control of agricultural projects using electronic soil measurement devices. The proposed methodology is aimed at managing the electronic irrigation process, reading the moisture percentage, elements of soil and controlling the addition of inorganic fertilizers. The system also helps in sending alert messages to the user when an error occurs in measuring the percentage of soil moisture specified for crop and a warning message when change happens to the fertility of soil as many workers find difficulty in daily checking of soil and operating agricultural machines such as irrigation machine and soil fertilizing machine, especially in large projects.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.38-48
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• 2006

A synchronous multicarrier (MC) code-division multiple access (CDMA) system using inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) for the downlink mobile communication system operating in a frequency selective Rayleigh fading channel is analyzed. Both carrier frequency offset and timing offset are considered in the analysis. Bit error rate performance of the system with both equal gain combining and maximum ratio combining are obtained. The performance is compared to that of the conventional system using correlation receiver. It is shown that when subcarrier number is large, the system using IFFT/FFT has nearly the same performance as the conventional one, while when the sub carrier number is small, the system using IFFT/FFT will suffer slightly worse performance in the presence of carrier frequency offset.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.89-92
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• 2005

For the past years, wireless communications environment have developed with explosive demand of internet service and increase of subscriber. Anytime anywhere, we can access internet service and recently, we can access internet with portable terminal using wireless communications. So several schemes have been proposed for the efficient service. In this paper, we may improve performance of wibro system using adaptive antennas scheme at the base station (BS) and mobile station(MS),operating jointly. In wibro system, the joint use of transmit beamforming at BS and receive beamforming at MS is improved the SINR and increased the capacity compared to conventional system[1],[2].