• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.637-644
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• 2020

VANET (Vehicular Ad Hoc Networks) is a network between vehicles and between vehicles and infrastructure. VANET-specific characteristics such as high mobility, movement limitation, and signal interference by obstacles make it difficult to provide stable VANET services. To solve this problem, this paper proposes a vehicle type-based priority clustering method that improves the existing bus-based clustering. The proposed algorithm constructs a cluster by evaluating the priority, link quality, and connectivity based on the vehicle type, expected communication lifetime, and link degree of neighbor nodes. It tries to simplify the process of selecting a cluster head and increase cluster coverage by utilizing a predetermined priority based on the type of vehicle. The proposed algorithm is expected to become the basis for activating various services by contributing to providing stable services in a connected car environment.

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.241-248
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• 2002

An electronic noses system including six metal oxide sensors was used to predict the characteristics of shelf-life of soybean curd. Soybean curd was stored at two different temperatures defined as low temperature(5$\^{C}$) and high temperature(25$\^{C}$). Resistance changes of the sensors were measured 13 times for 19 days at low temperature and 19 times for 120 hours at high temperature. Three different analytical methods such as graphical analysis(GA), principal component analysis(PCA), and cluster analysis(CA) were used to analyze sensors outputs. The ratio of resistance was decreased according to increasement of shelf-life. Using PCA it was possible to predict freshness and shelf-life time of soybean curds. Also, using CA it was possible to simplify an electronic nose system. Electronic nose system could be an efficient method to predict shelf-life and to evaluate quality in foods.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.289-307
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• 2010

We developed a photometric pipeline to be used for a wide field survey. This pipeline employs the difference image analysis (DIA) method appropriate for the photometry of star dense field such as the Galactic bulge. To verify the performance of pipeline, the observed dataset of the open cluster M11 was re-processed. One hundred seventy eight variable stars were newly discovered by analyzing the light curves of which photometric accuracy was improved through the DIA. The total number of variable stars in the M11 observation region is 335, including 157 variable stars discovered by previous studies. We present the catalogue and light curves for the 178 variable stars. This study shows that the photometric pipeline using the DIA is very useful in the detection of variable stars in a cluster.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.677-680
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• 2015

In this paper, we propsed scheme to mitigate conflict and loss of message in vehicle communication. And vehicles that exist in the moving direction, were grouping to the cluster form. Through, to select best relay vehicle, transmit a message to the destination. In addition, we applied the double rayleigh fading environment so that can applied in real-environments. Therefore, vehicle communication network applied proposed scheme, can be problem of mitigate conflict and loss of message. Thus, Increase the reliability of the received signal.

• Journal of Communications and Networks
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• v.12 no.2
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• pp.122-129
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• 2010

Energy conservation is one of the most important issues for evaluating the performance of wireless sensor network (WSN) applications. Generally speaking, hierarchical clustering protocols such as LEACH, LEACH-C, EEEAC, and BCDCP are more efficient in energy conservation than flat routing protocols. However, these typical protocols still have drawbacks of unequal and high energy depletion in cluster heads (CHs) due to the different transmission distance from each CH to the base station (BS). In order to minimize the energy consumption and increase the network lifetime, we propose a new hierarchical routing protocol, distance aware intelligent clustering protocol (DAIC), with the key concept of dividing the network into tiers and selecting the high energy CHs at the nearest distance from the BS. We have observed that a considerable amount of energy can be conserved by selecting CHs at the nearest distance from the BS. Also, the number of CHs is computed dynamically to avoid the selection of unnecessarily large number of CHs in the network. Our simulation results showed that the proposed DAIC outperforms LEACH and LEACH-C by 63.28% and 36.27% in energy conservation respectively. The distance aware CH selection method adopted in the proposed DAIC protocol can also be adapted to other hierarchical clustering protocols for the higher energy efficiency.

• Convergence Security Journal
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• v.8 no.1
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• pp.9-18
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• 2008

This paper propose CAR-TO-CAR protocol which can prevent the cars at high-speed from a multiple clash accident at highway with exchanging information. we construct cluster be linked with distance took from GPS(Global Positioning System) because there is no connection at cars on the road. The proposed method solved the overload problem by establishing route because construct the cluster at the IEEE 802.11 MAC class. 'Multi-hop Routing protocol' based on Active Network enable stable Network to be formed by using Active Network.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.1
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• pp.35-41
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• 2012

This paper proposes a moving object detection algorithm for active camera system that can be applied to mobile robot and intelligent surveillance system. Most of moving object detection algorithms based on a stationary camera system. These algorithms used fixed surveillance system that does not consider the motion of the background or robot tracking system that track pre-learned object. Unlike the stationary camera system, the active camera system has a problem that is difficult to extract the moving object due to the error occurred by the movement of camera. In order to overcome this problem, the motion of the camera was compensated by using SURF and Pseudo Perspective model, and then the moving object is extracted efficiently using stochastic Label Cluster transport model. This method is possible to detect moving object because that minimizes effect of the background movement. Our approach proves robust and effective in terms of moving object detection in active camera system.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.427-432
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• 2005

I studied about existent load distribution algorithms and the WLC(Weighted Least Connection) algerian that is using much at present to distribute the connection request of users to real servers efficiently in web cluster system. The efficiency of web cluster system is fallen by load imbalance between servers, because there is problem In inaccurate load status measuring of servers and measuring timing at these load distribution algorithms. In this paper, I suggest an algorithm that distributes load base on various load state of servers by real time using broadcasting RPC(Remote Procedure Call) when a user requests connection, and implement a prototype and experiment its performance. The experiment result shows that load imbalance phenomenon between reai sowers was improved greatly than existing method, and performance of web cluster system was improved by efficiency that response time is shortened.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.89-99
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• 2015

In this research, 1,032 data of precise safety inspection from 2004 to 2013 are gathered and constructed for finding effective safety inspection systems. Items are extracted from constructed data and factors for typology are decided with statistical method such as principle component analysis and cluster analysis. For factor decision, we extruded independent characteristics such as morphological and geographical characteristic, and deleted items which can be expressed by combination of independent characteristics. Four factors such as total storage, watershed ratio, levee length ratio, and spillway length ratio are extracted in this process. In cluster analysis, levee length ratio is excluded because it is not separated as cluster. Finally nine types of agricultural reservoir are extruded by total storage, watershed ratio, and spillway length ratio with frequency analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.4
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• pp.1535-1554
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• 2016

This paper proposes a novel channel assignment scheme called multi-cluster based dynamic channel assignment (MC-DCA) to improve system performance for the downlink of dense femtocell networks (DFNs) based on orthogonal frequency division multiple access (OFDMA) and frequency division duplexing (FDD). In order to dynamically assign channels for femtocell access points (FAPs), the MC-DCA scheme uses a heuristic method that consists of two steps: one is a multiple cluster assignment step to group FAPs using graph coloring algorithm with some extensions, while the other is a dynamic subchannel assignment step to allocate subchannels for maximizing the system capacity. Through simulations, we first find optimum parameters of the multiple FAP clustering to maximize the system capacity and then evaluate system performance in terms of the mean FAP capacity, unsatisfied femtocell user equipment (FUE) probability, and mean FAP power consumption for data transmission based on a given FUE traffic load. As a result, the MC-DCA scheme outperforms other schemes in two different DFN environments for commercial and office buildings.