• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3775-3788
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• 2014

With the increasing number of the wireless and mobile networks, the way that people use the Internet has changed substantively. Wireless multimedia services, such as wireless video streaming, mobile video game, and mobile voice over IP, will become the main applications of the future wireless Internet. To accommodate the growing volume of wireless data traffic and multimedia services, cognitive radio (CR) and Information-Centric Network (ICN) have been proposed to maximize the utilization of wireless spectrum and improve the network performance. Although CR and ICN have high potential significance for the future wireless Internet, few studies have been conducted on collaborative operations of CR and ICN. Due to the lack of infrastructure support in multi-hop ad hoc CR networks, the problem is more challenging for video streaming services. In this paper, we propose a Cross-layer Video Streaming Mechanism (CLISM) for Cognitive Radio Ad Hoc Information Centric Networks (CRAH-ICNs). The CLISM included two distributed schemes which are designed for the forwarding nodes and receiving nodes in CRAH-ICNs. With the cross-layer approach, the CLISM is able to self-adapt the variation of the link conditions without the central network controller. Experimental results demonstrate that the proposed CLISM efficiently adjust video transmission policy under various network conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5191-5211
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• 2016

It is essential to satisfy class-specific QoS constraints to provide broadband services for new generation networks. The present study proposes a QoS-driven multicast scheme for wireless networks in which the transmission rate and end-to-end delay are assumed to be bounded during a multiple multicast session. A distributed algorithm was used to identify a cost-efficient sub-graph between the source and destination which can satisfy QoS constraints of a multicast session. The model was then modified as to be applied for wireless networks in which satisfying interference constraints is the main challenge. A discrete power control scheme was also applied for the QoS-aware multicast model to accommodate the effect of transmission power level based on link capacity requirements. We also proposed random power allocation (RPA) and gradient power allocation (GPA) algorithms to efficient resource distribution each of which has different time complexity and optimality levels. Experimental results confirm that the proposed power allocation techniques decrease the number of unavailable links between intermediate nodes in the sub-graph and considerably increase the chance of finding an optimal solution.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.417-420
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• 1987

For an increased level of productivity, it is important that the end-point of a robot manipulator moves from an initial location to final position in the minimum time subject to the available maximum actuator's torque (or force) at each joints. The main issue is to develop an algorithm to compute the actuators in real-time. In this paper, a digital state feedback control algorithm has bean developed to obtain the near-minimum-time trajectory for the end-effector of a robot manipulator. In this algorithm, the poles of the linearized closed loop system are judiciously placed in the Z-plane to permit minimum-time response without violating the constraints on the actuator torques. The validity of this algorithm have been established using numerical simulations. A three-link manipulator in chosen for this purpose and results are discussed for three different combinations of initial and final station.

• Journal of the Korea Society of Computer and Information
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• v.21 no.8
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• pp.49-55
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• 2016

In this study, we proposed the social map system prototype for intelligent crime prevention. For developing the social map system prototype, functional requirements were derived through the analysis of related cases and preceding studies. Derived requirements are providing a variety of map-based safety information, using crowdsourcing data such as SNS, connecting to intelligent CCTV. To satisfy these requirements, the prototype is developed with four main menus: the integrated search menu including social media data, the safety map menu providing a variety of safety and danger information, the community map menu to collect safety and danger information from users, and the CCTV menu providing the link to intelligent CCTV. The social map for intelligent crime prevention in this study is expected to greatly enhance the safety of local community with the provision of prompt response to risk information, safe route, etc. through actual service and user participation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.451-462
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• 2016

Photovoltaic energy conversion becomes main focus of many researches due to its promising potential as source for future electricity and has many advantages than the other alternative energy sources like wind, solar, ocean, biomass, geothermal etc. In Photovoltaic power generation multilevel inverters play a vital role in power conversion. The three different topologies, diode-clamped (neutral-point clamped) inverter, capacitor-clamped (flying capacitor) inverter and cascaded h-bridge multilevel inverter are widely used in these multilevel inverters. Among the three topologies, cascaded h-bridge multilevel inverter is more suitable for photovoltaic applications since each pv array can act as a separate dc source for each h-bridge module. This paper presents a single phase Cascaded H-bridge five level inverter for grid-connected photovoltaic application using sinusoidal pulse width modulation technique. This inverter output voltage waveform reduces the harmonics in the generated current and the filtering effort at the input. The control strategy allows the independent control of each dc-link voltages and tracks the maximum power point of PV strings. This topology can inject to the grid sinusoidal input currents with unity power factor and achieves low harmonic distortion. A PID control algorithm is implemented in Arm Processor LPC2148. The validity of the proposed inverter is verified through simulation and is implemented in a single phase 100W prototype. The results of hardware are compared with simulation results. The proposed system offers improved performance over conventional three level inverter in terms of THD.

• Journal of The Korea Institute of Healthcare Architecture
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• v.19 no.3
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• pp.7-19
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• 2013

Purpose: The main objective of this paper is, first, to assess a body of research evidence that articulates the impact of environmental and design factors on safety, quality of life, and health of the elderly who reside in geriatric hospitals or other elderly care facilities and, second, to draw out design implications that can be incorporated into design process and design decisions to help create healing environments for the elderly. Methods: Extensive literature review has been conducted to identify rigorous empirical studies that link the design of elderly care facilities to health-related outcomes and scrutinized peer-reviewed articles published in many different fields including architecture, psychology, nursing to gerontology. Results: The review found a growing body of rigorous studies that identified physical environmental and design factors that improve safety, quality of life, and health of the elderly in geriatric hospitals or other elderly care facilities. Implications: The findings of the review can be translated to design decisions to promote safety, quality of life, and health of the elderly in geriatric hospitals or other elderly care facilities.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.577-586
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• 2011

This paper describes the development of hardware simulator for the operation analysis of DC microgrid. The hardware simulator consists of several distributed power sources such as a wind power generation, solar power and fuel cell, and two energy storages such as a supercapacitor and battery. The main controller which performs a role of energy management and state monitoring is connected with the local controller in each power source and storage through ethernet-based communication link. The developed hardware simulator can be utilized to analyze the performance DC microgrid with practical manner.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1125-1127
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• 1998

Inchon International Airport(IIA) is constructed for Northeast Asia Gate as is important for IIA to become a 21 century's leader in the world. as is planned for open at December 2000 as a important economic link for unified korea. Power System is designed through investigation of advanced domestic and international example. In addition to power facility operation it is designed for using an information infrastructure of whole airport. IIA Power System Design make instantaneously the Power Distribution Facilities and the SCADA System to construct the airport. and the Airport Power Information System to operate the Power System. It is designed to take efficient and safe Power System including the advanced technology. Power System make the integrated Power Information Database to operate the Main Control Center, analyze the data about the relation of the Power System and Airport operation, and will support the important files in the future.

• Korean Journal of Agricultural Science
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• v.28 no.2
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• pp.132-146
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• 2001

Rice cultivation is not only the main resource of farm income and staple food but also the root of cultural life of Korean people. Korean government has carried out irrigation water development with heavy investment to cope with water shortage in rice fanning as a link of the five years economic development plans. In spite of the continuous accomplishment of irrigation water development, the marginal benefits-costs of irrigation water has not been studied. Owing to the government full support for the operation and maintenance of irrigation facilities, price of irrigation water as a membership fee could not be formed as the municipal and industrial water prices. Accordingly this study is aimed at identifying firstly the marginal benefits-cost of irrigation water, secondly deriving the macro-econometrics models as supply and demand functions of irrigation water and thirdly examining the marginal benefits-cost ratio. The trends of supply and demand prices of irrigation water were estimated annually. Considering the marginal benefits-cost ratio as 1.3, it was identified that additional irrigation water development projects still have an economic feasibility under the present economic situation in Korea.

• ETRI Journal
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• v.37 no.5
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• pp.867-876
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• 2015

This paper proposes an efficient interference control scheme for vehicular moving networks. The features of the proposed scheme are as follows: radio resources are separated into two resource groups to avoid interference between the cellular and vehicle-to-vehicle (V2V) links; V2V links are able to share the same radio resources for an improvement in the resource efficiency; and vehicles can adaptively adjust their transmission power according to the interference among the V2V links (based on the distributed power control (DPC) scheme derived using the network utility maximization method). The DPC scheme, which is the main feature of the proposed scheme, can improve both the reliability and data rate of a V2V link. Simulation results show that the DPC scheme improves the average signal-to-interference-plus-noise ratio of V2V links by more than 4 dB, and the sum data rate of the V2V links by 15% and 137% compared with conventional schemes.