• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.168-174
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• 2007

In this paper, we propose a reversible watermarking algorithm where an original image can be recovered from the watermarked image. Most watermarking algorithms cause degradation of image quality in original digital contents in the process of embedding watermarks. In the proposed algorithm, the original image can be obtained when the degradation is removed from the watermarked image after extracting watermark information. In the proposed algorithm, we utilize a peak point of image histogram and the location map and modify pixel values slightly to embed data. Because the peak point of image histogram and the location map are employed in this algorithm, there is no need of extra information transmitted to the receiving side. As the locations watermark embedding are identified using the location map, the amount of watermark data can increase through recursive embedding.

• Convergence Security Journal
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• v.15 no.3_1
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• pp.83-90
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• 2015

Current PKI system will confront more dangerous elements in the wireless network. Accordingly, this study suggests a plan to strengthen authentication system plan with using access control and encryption to the location. Locational information collecting devices such as GPS and sensor are utilized to create a new key for authentication and collect locational information. Such a key encodes data and creates an authentication code for are access control. By using the method suggested by this study, it is possible to control access of a military secret from unauthorized place and to protect unauthorized user with unproposed technique. In addition, this technique enables access control by stage with utilizing the existing PKI system more wisely.

• Journal of Internet Computing and Services
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• v.11 no.1
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• pp.15-20
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• 2010

In this paper, we propose a novel approach to reduce spatial query access latency and energy consumption by leveraging results from nearby peers in wireless broadcast environments. We propose a three-tier Hierarchical Location-Based Sequential access index, called HLBS, which provides selective tuning (pruning and searching entries) without pointers using a linear accessing structure based on the location of each data object. The HLBS saves search cost and index overhead, since the small index size with a sequential index structure results in low access latency overhead and facilitates efficient searches for sequential-access media (wireless channels with data broadcast). Comprehensive experiments illustrate that the proposed scheme is more efficient than the previous techniques in terms of energy consumption.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.126-129
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• 2021

The existing drainage facility management system is not systematically computerized, and it is difficult to manage each drainage facility on-site due to insufficient information and location management. Currently, in the current drainage system management, repair technicians recognize the information of the drainage facility by recognizing the QR code at the site. These methods have difficulty locating QR codes in the field, and the problem is that they incur additional maintenance costs due to loss and breakage of QR code attachments. The GPS-based drainage management system proposed in this paper stores and manages each drainage facility's data including GPS information, allowing applications to use the location and information of drainage facilities based on user location data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.957-960
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• 2006

In this paper, we studied the location estimation algorithm of a spatial 3 dimension which extend the location estimation algorithm of a plane 2 dimension in 2.45GHz band RTLS(Real time location system). We used TDOA scheme which need not a time of transmission information of the tag and estimated 3 dimension coordinates. Also, estimated intersection of hyperbolic curve to X, Y coordinate of the tag at 2D coordinates searching area, $300m\times300m$ and LOS propagation environments. And, we estimated Z coordinate ultimately using X, Y coordinate. The location estimation algorithm of a spatial 3 dimension satisfies the RTLS specification requirement, 3m radius accuracy. From the result, we confirm that the location of tag which similar to actual coordinate in the case to an ideal received offset. However, we verified that the location of tag which escapes from a radius 3m within error range when received offset increased. Therefore, as the future work we are consider enhanced location accuracy of a spatial 3 dimension in RTLS system which using the decrease scheme of reader offset or the discriminate scheme of the estimation location.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1715-1722
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• 2010

In this paper we consider methods for selecting the next tracing node that take advantage of the history of traced positions during the packet-tracing. In the meantime, the proposed routing strategy that counters the tracing is to design the routing path is such a way that nodes on it are not close to the nodes whose location privacy is needed and zigzag or back-and-forth movements hardly take place. In simulations, the ratios of successful tracing were largely improved. It was shown that our routing scheme allows more data packets to be delivered to the destination while, enticing the tracer to move more long distances in the presence of multiple assets.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.122-124
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• 2010

WPS(Wifi Positioning System) is a location determination technique that utilizes AP information scattered all over the real world. In general, the finger print technique is used for location calculations in WPS. However the finger print technique is a location determination technique that utilizes average values and has problems in the accuracy of the location determination. It also shows low performance of the system due to arithmetic operations. In this paper, the MSS(Max Signal Strength) method is proposed to resolve the existing problems in the finger print technique. The proposed method can reduce the operation time and improve the accuracy of the system under the same conditions. Test environments of the system is presented and the performance of the system is analyzed to verify the methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.846-849
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• 2008

In recent years there has been growing interest in wireless sensor networks (WSNs) for a variety of indoor applications. In this paper, we present the RSSI-based localization in indoor environments. In order to evaluate the relationship between distance and RSSI, the log-normal path loss shadowing model is used. By tagging users with a sensor node and deploying a number of nodes at fixed position in the building, the RSSI can be used to determine the position of tagged user. This system operates by recording and processing signal strength information at the base stations. It combines Euclidean distance technique with signal strength matrix obtained during real-time measurement to determine the location of user. The experimental results presented the ability of this system to estimate user's location with a accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.712-721
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• 2012

In this paper, we propose an Enhanced cross-layer Geographic Forwarding (EGF) protocol for wireless sensor networks (WSNs). EGF uses an optimal back-off time to make the packet forwarding decisions using only source and destination's location information and energy cost without information about neighbor nodes' location or the number of one hop neighbor nodes. EGF is also a cross-layer protocol by combining efficient asynchronous MAC and geographic routing protocol. The proposed protocol can find optimal next hop location quickly without broadcasting node's location update and with minimizing overhead. In our performance evaluation, EGF has better performance in terms of packet success ratio, energy efficiency and end-to-end delay in wireless sensor networks.

• The KIPS Transactions:PartD
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• v.17D no.1
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• pp.53-58
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• 2010

This research aims to develop practical location-based services that provide users with personalized theater guide services on smart phones. In this research, we have designed and implemented a smart theater guide system for Deahakro, Seoul based on smart phones incorporating GPS. This system first identifies the current position using GPS, and maps the current position onto the map. It is designed and implemented to provide users with personalized information service about the plays and the theaters nearby the current position. It is also optimized to be useful effectively by performing on-site experiments.