• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1204-1227
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• 2020

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data transmission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Diminishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy efficiency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collaborations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.581-589
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• 2013

Generally, Sewage Treatment Plants(STPs) are complexes systems in which a range of physical, chemical and biological processes occur. However, their performance strongly depends on the know-how acquired by the field-engineer. Recently, in order to solve this situations, various operation and management technologies based on the Instrumentation, Control and Automation(ICA) have been developed. As a economies-environmental affect point of view, this study was for the performance evaluation and assessment of results from the Smart Operation System(SOS) in full-scale STP. The SOS in STP consisted of the process monitoring module, including real-time influent prediction and effluent simulation, and the Smart Air Control(SAC) module. According to the results from field test for 2 years, the results of economical evaluation, amount of benefits and cost saving by the SOS have shown to be much higher than that of traditional operation. Nevertheless, the removal load(kg/yr) of BOD 13.3 %, COD 28.2 %, TN 44.4 % and TP 20.8 % were increased, respectively. Remarkable improvement of removal load could be achieved after the SOS was adapted. It was concerned that the SOS offer a user friendly functionalities and cost saving needed by the field-engineers. In addition, it was expected that the results of this study would supply helpful information for design and cost saving for the SOS in full-scale STP.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.955-962
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• 2016

In recent years, there have been emerging needs for standardized software-based motion application development for better scalability and support for multiple operation modes for small quantity batch production. Although a software-based motion system provides a basis for constructing multiple operation modes on a machine, it is not easy to construct such systems without tools for defining multiple motion operation modes and standardized mode-change protocols. This paper proposes a motion recipe concept to overcome this problem; the concept includes the authoring of multiple motion operation modes using the PLCopen-compliant motion function blocks and communication protocols to trigger operation mode changes from an external interface. The motion recipe was implemented by extending an IEC 61131-3 compliant IDE called Beremiz, and the correctness of the motion recipe-based application behavior was verified on a real testbed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1973-1980
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• 2015

The combat system has a different purpose depending on its mission. All functions of combat system are important, but, the components that related main functions for the purpose, are important than other components. Also, the hit probability of component is proportional to area of the component. Therefore, when we analyze vulnerability of combat system, to consider the importance and hit probability of component. Thus to improve reliability of combat system, we apply the analyzed result to design combat system. In this paper, we develop a vulnerability analysis program based on criticality which calculated from importance and hit probability of components by related researches. To do this, we propose a methodology to apply criticality of components, and define classification rates for calculating criticality based on FMECA. Additionally, we propose a technique of vulnerability analysis using criticality of components, and apply the proposed technique to develop and test the vulnerability analysis program for automation of analysis.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.2
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• pp.10-15
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• 2010

The subject of basic fluid power practice which is used in various industries requiring factory automation aims at understanding of the composition and operating principles of pneumatic components and programming of electric sequential circuits, building the design ability of pneumatic system. This subject goes by 3 hour classes with theory and practice side by side. So it is not enough time to instruct students various contents related in this subject. In this research a supplementary learing using E-learning is proposed as a solution for this problem. The off-line classes of this subject went with E-learning side by side and analyzed the effects of E-learning as a supplementary learning through the students survey who attended the class. And further needed research is presented.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.642-647
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• 2006

Recently Ministry of National Defense is reconstructing old facilities using modular construction method for enhancing soldiers' quality of living. In the future, the use of modular construction method is expected to be increased. But in beginning stage as ROK military facilities that was built by modular was not designed and constructed efficiently, problems for pilot projects need to be analyzed by phases and construction methods should be improved. For the maximized efficiency, design should be made to minimize on-site works, factory automation in an assembly plant should be installed for the better productivity, roads that will be used for transportation should be checked, and joint and connection methods between modules in on-site assembly should be improved for a better quality.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.115-124
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• 2002

This paper presents an active auxiliary edge-resonant DC link snubber with a ringing surge damper and a three-phase voltage source type zero voltage soft-switching inverter with the resonat snubber treated here for the AC servo motor driver applications. The operation of the active auxiliary edge-resonant DC link snubber circuit with PWM voltage is described, together with the practical design method to select its circuit parameters. The three-phase voltage source type soft-switching inverter with a single edge-resonant DC link snubber treated here is evaluated and discussed for the small-scale permanent magnet (PM) type-AC servo motor driver from an experimental point of view. In addition to these, the AC motor stator current and its motor speed response for the proposed three-phase soft-switching inverter employing Intelligent Power Module(IPM) based on IGBTS are compared with those of the conventional three-phase hard-switching inverter using IPM. The practical effectiveness of the three-phase soft-switching inverter-fed permanent magnet type AC motor speed tracking servo driver is proven on the basis of the common mode current in a novel type three-phase soft-switching inverter-fed AC motor side and the conductive noise on the mains terminal interface voltage as compared with those of the conventional three-phase hard-switching inverter-fed permanent magnet type AC servo motor driver for the speed tracking applications.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.119-128
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• 2004

With the growing traffic density and increasing comfort requirements, the automation of the drive train will gain importance in vehicles. The automatic clutch actuation relieves the drivers especially in urban driving and stop-and-go traffic conditions. This paper describes the dynamic modeling of a clutch actuator and clutch spring. The dynamic model of the clutch system is developed using MATLAB/Simulink, and evaluated by experimental data using a test rig. This performance simulator is useful to develop the clutch-by-wire (CBW) system for an automated manual transmission (AMT). The electro-mechanical type CBW system is also implemented as an automatic clutch for AMT. The prototype of CBW system is designed and implemented systematically, which is composed of an electric motor, worm gear and slider-crank mechanism. The test rig is developed to perform the basic function test of the automatic clutch, and the developed prototype is validated by the experimental data on the test rig.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1199-1208
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• 2019

Korea's protected horticulture is rapidly increasing in scale due to various advantages such as year-round harvesting, labor savings through automation and shortened culture period, and greater income generation. This study was conducted to investigate the impact of protected horticulture on water quality. The results of this study are expected to provide basic data contributing to improvements towards sustainable agriculture and eco-friendly design of protected horticulture complex. The average T-N and T-P loads from vinyl greenhouses were 286.55± 143.98 mg/L and 59.14±13.77 mg/L, respectively and those from glass greenhouses 380.68 ± 150.41 mg/L and 61.85±20.72 mg/L. The annual discharge of wastewater derived from the monthly discharge from the horticulture greenhouses were estimated at 2597 ton/ha, with the annual phosphorus load amounting to 155.3 kg/ha. The average T-N and T-P loads in the tested greenhouse effluents were in excess of 8.3- and 13.5-fold the standards for the Korean wastewater plant effluent. The waste nutrient solution discharged from a protected horticulture complex can cause water contamination. Therefore, there is a need to conduct follow-up research using a water purification system or a trench method to develop a eco-friendly protected horticulture complex for sustainable agriculture.

• Journal of Engineering Education Research
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• v.11 no.1
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• pp.76-84
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• 2008

The purposes of the study were to identify the concept of teaching portfolios, learning portfolios, and its contents and to investigate the foreign universities' application of teaching and learning portfolios on their professorship and teaching achievement evaluation. To have rationale for the study, literature review and data collection methodology were hired. The concept of teaching and learning portfolios have been used in many ways of meaning as well as in multiple approach in teaching-learning processes. The selected ten foreign universities have had teaching and learning portfolios on their professorship and teaching achievement evaluation as a way of promotion and or incentives to employment decisions. On the other hand, domestic universities do not have the system yet, or they are launching it to enact with infusing engineering program. It is also proposed that to improve the quality of the education program, learning portfolios should be used much more than lecture plan used. Learning portfolios should be developed by learners to coping with the teaching portfolio in all teaching and learning processes.