• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.935-939
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• 2015

This paper describes sensorless speed control of brushless DC motors by using direct torque control. Direct torque control offers fast torque response, robust specification of parameter changes, and lower hardware and processing costs compared to vector-controlled drives. In this paper, the current error compensation method is applied to the sensorless speed control of a brushless DC motor. Through this control technique, the controlled stator voltage is applied to the brushless DC motor such that the error between the stator currents in the mathematical model and the actual motor can be forced to decay to zero as time proceeds, and therefore, the motor speed approaches the setting value. This paper discusses the composition of the controller, which can carry out robust speed control without any proportional-integral (PI) controllers. The simulation results show that the control system has good dynamic speed and load responses at wide ranges of speed.

• KIEAE Journal
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• v.7 no.1
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• pp.5-13
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• 2007

Since aging has become one of most hot and serious issues in the whole global world, universal design as a strategic concept to enable the elderly age in place has received much attention and its importance is getting recognized. Japan has undergone the Aging phenomenon much earlier than Korea and other countries. During that time, through much trials and errors, it accumulated the wisdoms and techniques to precede aging friendly environment and products. Therefore current Japan house is a comprehensive setting which embraces lots of universal design features that has a valuable implication for Korean development that faces fast aging future. The purpose of this study was to delineate characteristics of universal design features appeared in Japanese Model houses. One site of housing park in the city where various model houses of representative housing construction companies was selected as a cluster area for data collecting. Data were collected mainly through field survey at the housing park of Tokyo during November, 2006, and additional data were collected through website and company information of relevant company. Universal design features were extracted for 17 houses of the housing park and sorted and analyzed according to the analysis frame. The frame were made using 2 major clusters; space area, and 8 universal design principle. Results showed a range of universal design feature and its detail universal design principle satisfied. The 8 principle currently developed became to house realistic practical examples and theory became proved its impractical power. The academic, educational and industrial implication were documented.

• Journal of Aquaculture
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• v.16 no.1
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• pp.44-50
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• 2003

This study aimed to develop the methods of growing Enteromorpha prolifera natural seedlings in its natural habitat and artificial indoor seedlings by inducing spore release. Likewise, the study examined the possibility of mass production by developing cultivation techniques with cultivating examination. The natural seedling of E.prolifera thrived in a sea area composed of sand and mud, which Is its natural habitat. Growing of this alga on the seedling frame 20 cm high from the bottom at the intertidal zone in summer and 40 cm high in fall was found to be very effective. However, enabling the best attachment rate for artificial indoor seedling requires inducing spore release after drying the mature thalli in a dark place fur about 12∼24 hours and setting seedling nets in a dark water tank (spore solution) for 24 hours. Breeding E.prolifera in a pole-system farm is best done in shallow sea areas with mud or mud and sand geological feature. However, floating-system lam is better for deep-sea areas with fast current. Ideal farming places are sea areas with plenty of nutritional salt and safe places that protect the lam facilities against billows. Furthermore, an exposure method on seawater surface to produce larger output should be used.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.3
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• pp.88-97
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• 2000

This paper presents motion estimation method using region segmentation information Motion estimation which is very difficult to be implemented only by software because of intensive computation cost, is implemented by special-purpose hardware in real-time applications In this paper, we propose region based motion estimation algorithm which can reduce the computation cost by using region segmentation information and setting the variable search window compared with FSMA algorithm Secondly, another proposed algorithm is to segment semantic region like face for selective coding and transfer of semantic region using segmented region information This work alms to improving the subjective quality of skin color region or face region m the picture that has slow motion and IS mainly composed of one or two speakers of video conference and video telephony applications.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.1-10
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• 2001

The 3-step cell search has been considered for fast acquisition of the scrambling code unique to a cell in the W -CDMA system. In this paper, the performance of the cell search scheme is analyzed in Rayleigh fading channels. And the system parameters for cell search scheme and the design parameters for the receivers are examined. The probabilities of detection, miss and false alarm for each step are derived in closed forms based on the statistics of CDMA noncoherent demodulator output. Through the analysis, the effect of threshold setting and post detection integration for each step is investigated, and the optimal values of the power allocation for the synchronization channels are also considered. The number of post-detection integrations for each step is a design parameter for the receiver, and the optimum values may depend on not only the power allocation for each channel related to the cell search, but the false alarm penalty time. It is shown that optimal values could be determined through the analysis. Also, the cumulative probability distribution of the average cell search time is obtained.

• Journal of Digital Contents Society
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• v.15 no.1
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• pp.93-99
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• 2014

Recently Wireless communication among short-distance devices has come to notice due to smart phone generalization recently. However, instead of setting up additional H/W, communication technology providing wireless communication based on S/W is in need due to limited availability of NFC's use. Accordingly, short-distance wireless communication technology that makes great use of mike and speaker which installed in every device draws attention. Our thesis suggests improvement of acoustic transmission speed by applying multi-channel parallel transmission and advancement of transmission rate that differed from each mike's own characteristics through optimizing adaptive threshold. The study is not only just applied in specific and limited conditions such as promoting corporation and payments system but also fast and convenient data transmit system general users-oriented.

• Journal of the Korea Convergence Society
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• v.6 no.2
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• pp.49-55
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• 2015

Quantum dot technology can be complementary application of the bulk material, and that a wide range of applications that can take advantage of the characteristic convergence technology. With the development of quantum dot technology, it is important to analyze Marketability of quantum technology, business opportunity. In this study, patents, papers, market, analysis of the project will be to investigate the quantum information research trends. Research results are expected to be used as a basis for research and development path setting and strategic planning of the quantum dot. In particular, this study found the performance of quantum dot research through patents and papers analyzed. In addition, fast-growing field, the field to lead the commercialization were derived. Compared to the advanced research and national research was to diagnose the domestic research into quantum dots.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.559-566
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• 2016

Software defined network (SDN) can effectively improve the performance of traffic engineering and will be widely used in backbone networks. Therefore, new energy-saving schemes must take SDN into consideration; this action is extremely important owing to the rapidly increasing energy consumption in telecom and Internet service provider (ISP) networks. Meanwhile, the introduction of SDN in current networks must be incremental in most cases, for technical and economic reasons. During this period, operators must manage hybrid networks in which SDN and traditional protocols coexist. In this study, we investigate the energy-efficient traffic engineering problem in hybrid SDN/Internet protocol (IP) networks. First, we formulate the mathematical optimization model considering the SDN/IP hybrid routing mode. The problem is NP-hard; therefore, we propose a fast heuristic algorithm named hybrid energy-aware traffic engineering (HEATE) as a solution. In our proposed HEATE algorithm, the IP routers perform shortest-path routing by using distributed open shortest path first (OSPF) link weight optimization. The SDNs perform multipath routing with traffic-flow splitting managed by the global SDN controller. The HEATE algorithm determines the optimal setting for the OSPF link weight and the splitting ratio of SDNs. Thus, the traffic flow is aggregated onto partial links, and the underutilized links can be turned off to save energy. Based on computer simulation results, we demonstrate that our algorithm achieves a significant improvement in energy efficiency in hybrid SDN/IP networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.807-810
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• 2005

Constructed network test environment of wireless base for confidentiality guarantee of data and safe transmission that is transmited at Mobile node of Wireless Network environment in this paper. And, progressed research about IKEv2's Multiple-Key Exchange mechanism for efficient security transmission that use IPSec that is built-in to basis to IPv6 of Mobile environment. Have several key to single terminal to solve that is seam at hand off packet transmission process of Mobile Node in Wireless Network and Re-setting for Key and Re-exchange problem that happen frequently and studied technology that move. Key exchange protocol that is used for an experiment loads basically in MIPv6 and used IKEv2 protocol that is used for management and distribution of reliable encryption key between both end. Using network simulator of SSFNet(Scalable Simulation Framework Network Models) in this paper Key exchange delay value of IKEv2's security transmission analyzing comparison Performance measure and studied about problem and improvement way accordingly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.204-207
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• 2009

This paper presents how to implement Markerless Augmented Reality and how to create and apply reference data sets. There are three parts related with implementation: setting camera, creation of reference data set, and tracking. To create effective reference data sets, we need a 3D model such as CAD model. It is also required to create reference data sets from various viewpoints. We extract the feature points from the model image and then extract 3D positions corresponding to the feature points using ray tracking. These 2D/3D correspondence point sets constitute a reference data set of the model. Reference data sets are constructed for various viewpoints of the model. Fast tracking can be done using a reference data set the most frequently matched with feature points of the present frame and model data near the reference data set.