• Journal of the Korean Institute of Educational Facilities
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• v.9 no.5
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• pp.5-12
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• 2002

High-speed telecommunication has brought variety of changes in every field of the world at large. In the field of education, use of multimedia has been positively introduced as teaching and learning tools. In addition, introduction of remote education as well as information and communication technology (ICT) has led an educational system gone into melting pot. These changes have known to be impossible without the provision of the infrastructure of telecommunications such as cabling, cable pathway, telecommunication equipments, and space for the equipments. Although the infrastructure of telecommunications should be fully considered from the early stage of the building design, most of the existing buildings have only cabling for voice communication such as telephone. As a result, heavy expenses are required for the installation of new telecommunication equipments. Such problems as defilement of the appearance of the building and a falling-off in reliability of telecommunication line are caused by the exposed cabling, when the cabling pathway and/or the space for the equipments are not reserved. Considering over 70% of error in telecommunication is coming from the cabling in building, it is necessary to reserve the space for efficient maintenance of the cabling and the equipments. In recent years, the national standard(TTAS.KO-04.0005) on the reservation of space for telecommunication cabling and equipments in residential and commercial building is established and applied for the building design. As well, the standard is in force for the educational buildings. In this study, we try to provide the guidelines for the design of telecommunications infrastructure in educational buildings for the purpose of efficient operation of education information and ICT.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.520-527
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• 1988

Liquid ejectors are widely used as marine pumps, inducer stage for the boiler feed water pump, boiler recirculating pump, cooling water recirculating pump in boiling water type nuclear reactor and a deep well pump, because of their high working confidence and simplicity. Furthermore, it requires only a modest net positive suction head for cavitation-free operation and it can be installed in remote location from mechanical power source. It is not easy to presume the friction losses, because it is complicately affected by area ratio, flowrate ratio, nozzle spacing, throat length, shape of liquid ejector and so on. Therefore, the optimization of liquid ejector design is still dependent, to a large extent, on the experimental results and empirical procedures. On the design of the liquid ejector, the area ratio and the nondimensional throat length are the most important design factors among the mentioned above. In this experiment, the effects of the area ratio and the nondimensional throat length to ejector efficiency are carried out systematically by the combination of 4 kinds of motive nozzle and 2 kinds of throat length. In this paper, the present experimental results are compared with the calculated ones by the previous computer aided design program based on one dimensional flow equation. And also, an empirical equation for the working limit of liquid ejector is reported.

• Journal of IKEEE
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• v.24 no.2
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• pp.392-402
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• 2020

This paper proposes a solar tracking system without photo-sensors. The system can be classified into four modules: Solar Tracking, MPPT, ESS, and Real-Time Monitoring. Nine solar panels, as a basic unit, are adopted with grid structures of different heights to reduce wind influence and to enable solar tracking without photo-sensors. The low-cost MCU implements MPPT method which generates PWM switching signal for boost converter. The unit of ESS consists of three-series and four-parallel lithium-ion batteries in order to enable monitoring for abnormalities in temperature and electrical characteristics of battery. Four MCUs used in the system consists of two AVR Atmega128, and two Raspberry PI, and they exchanges operation informations. Experimental results of the proposed system show the solar tracking performance, the possibility of on-site and remote monitoring and the convenience of maintenance based on IoT technology.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.145-151
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• 2017

In this paper, we propose the design and implementation of the system that is predicting the failure of ballast water treatment system by analysing its sensor datum and is reserving the most effective service center for sellecting the repair location on the way to the destination port. These data are collected in real time during draining or filling up the sea water from/to the ship, and it is essential to preliminarily repair the equipment showing unstable characteristics by analyzing the normal and abnormal data characteristics. We proposed a software platform for predicting and repairing faults by selecting the most efficient repair center based on this e-Navigation while the vessel is navigating to the next destination port. This system, as announced by the IMO Convention for the Prevention of Marine Pollution in 2017, provides a stable economic impact from stable cargo operation and stable out/in from/to port and marine ecosystem.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.17-25
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• 2020

In this paper, we deal with a system that provides temperature, humidity and fine dust data around infants to parents through Arduino and Raspberry Pi. It controls the operation of the mobiles remotely through applications. Android applications can perform the following functions. First, the infant's surrounding temperature, humidity and fine dust data are received. Second, mobile controls the smart mobile remotely. Third, recording and playing the voices of parents and enhancing the convenience of parenting. Through the experiment of measuring the operating time of the remote control module, it was confirmed that the application can quickly access the system. Existing products on the market do not provide environmental information around the infants and application that has various functions. The system covered in this paper is expected to improve child-rearing convenience by providing parents environmental information around infants, remotely controllable function and convenient functions of the application.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.73-80
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• 2008

The recent trend in home network system includes intelligent home environments that remote monitoring and control service is achieved without restrictions by device types, time, and place. Also the use of a vacuum robot in homes is gradually generalized on account of the convenience of the use. In this paper, we proposed and realized new home-monitoring system with the employment of an self-movement robot as one trial for realizing an intelligent home under home network environment. The proposed system can freely monitor every where in home, because the system effectively overcame the surveillance limitations of the existing monitoring system by attaching a Wireless Router and WebCam to a commercial vacuum robot. The outdoor users of this system can readily monitor any place which they want to supervise by controlling a vacuum robot with mobile telecommunication devices such as PDA. The wireless router installed with Linux operation system "OpenWrt" made it possible for the system users to transmit images and to control a vacuum robot with RS-232 communication.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1191-1202
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• 2013

The former researches on earthwork automation were mainly focused on GPS and sensor application, environment modelling, equipment path planning, work information management, and remote control etc. Recently, reducing $CO_2$ emission becomes one of main focuses for an automation research. In the case of earthwork operations, many kinds of construction machines or robots are involved, which can cause high level of $CO_2$ in a construction site. An effective earthwork plan and construction machine operation can both increase productivity and safety and decrease $CO_2$ emission level. In this research, some automation concepts for green earthworks are suggested such as a 3D construction site model, a 3D earthwork distribution based on two different earthwork methods, and an earthwork package construction method. A excel-based simulator is developed to generate the 3D earthwork distribution and to estimate the level of $CO_2$ emission for the given earthwork.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.107-108
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• 2019

In the past, regional pilot service is provided by individual pilots directly on board each ship, but it will be difficult to provide this type of service in the near future when autonomous vessels are activated. This can be seen as the need for automation and intelligence of pilot service and provision of remote control system. In this paper, we propose a method, system, and service target that can carry out the electronic pilot service through the intelligence aids to navigation for smart port operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1957-1963
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• 2017

This paper has proposed a new-type groundwater auto-monitoring system based on Multi-Sensor Device. The system adopted Multi-Sensor Device as host computer of data acquisition, used Windows Mobile which was prevalent operation system of Multi-Sensor Device. It adopted serial port CAN and RS485 as the communication interface between goundwater sensor Device and monitor host machine and utilized serial-linked multi-sensor design to measure effectively according to the depth of groundwater. We present a design for a groundwater monitoring system based on a network of wirelessly linked sensors. The proposed solution will enable groundwater researchers and decision makers to have quick access to the groundwater data with less effort and cost. Though our design is initially meant for groundwater monitoring, it can be easily adapted to other fields of environmental monitoring.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.6
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• pp.583-591
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• 2000

Caching mechanisms have been studied extensively to buffer the speed gap of hierarchical storages in the context of cache memory, paging system, and buffer management system. As the wide-area distributed environments such as the WWW extend broadly, caching of remote objects becomes more and more important. In the wide-area distributed environments, the cost and the benefit of caching an object is not uniform due to the location of the object; which should be considered in the cache replacement algorithms. For online operation, the time complexity of the replacement algorithm should not be excessive. To date, most replacement algorithms for the wide-area distributed environments do not meet both the non-uniformity of objects and the time complexity constraint. This paper proposes a replacement algorithm which considers the non-uniformity of objects properly; it also allows for an efficient implementation. Trace-driven simulations show that proposed algorithm outperforms existing replacement algorithms.