• Journal of KIISE:Computing Practices and Letters
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• v.15 no.8
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• pp.606-610
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• 2009

In Location-Based Service (LBS), a scheme to hide the exact locations of users is required for privacy protection, In this paper, we propose a grid-based cloaking method considering K-anonymity and L-diversity. For this, our method creates a minimum cloaking region by finding L number of buildings (L-diversity) and then finding number of users (K-anonymity). Especially, we use a effective filtering method for generating the minimum cloaking region in a fast way. Finally, we show from a performance analysis that our cloaking method outperforms the existing method, in terms of query processing time based on the size of cloaking regions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.875-880
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• 2011

We design and analyze the cloaking circuit using 2D transmission line structure to make up for the weakness of the established cloaking circuit using only lumped inductor and capacitor elements. The 2D transmission line structure enables one to conveniently design the cloaking circuit with available element values. All the necessary analysis and synthesis(design) formulas have been derived. A cloaking circuit for a cylindrical scatterer in free space has been designed based on the provided design formulas and its effects have been investigated using the circuit simulator ADS. The effect of the cloaking medium for this specific case has been observed to be about 10.5 dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.929-938
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• 2011

The setting algorithm of cloaking region using dummy which is proposed in this paper solves the problem which counts the building with duplication that exists in several cells of Privacy Grid by adding the building grouping item to the index structure of the existing Privacy Grid, and by increasing K value after searching the contiguous cells in the comer of each building, the exposure problem of private location information due to the minimum cloaking region setting of the existing GBC is solved. In addition, this paper reduces the searching time of K value by setting smaller cloaking region than Privacy Grid and GBC with dummy K before expanding cloaking region and strengthens the location information protection of users using dummy K.

• Journal of Korea Spatial Information System Society
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• v.10 no.4
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• pp.1-10
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• 2008

In wireless internet, the location information of the user is one of the important resources for many applications. One of these applications is Location-Based Services (LBSs) which are being popular. Because, in the LBS system, users request a location-based query to LBS servers by sending their exact location, the location information of the users can be misused by adversaries. In this regard, there must be a mechanism which can deal with privacy protection of the users. In this paper, we propose a cloaking method considering both features of K-anonymity and L-diversity. Our cloaking method creates a minimum cloaking region by finding L number of buildings (L-diversity) and then finding number of users (K-anonymity). To support this, we use a R*-tree based index structure and use filtering methods especially for the m inimum cloaking region. Finally, we show from a performance analysis that our method outperforms the existing grid based cloaking method.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.115-126
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• 2009

Recent development in wireless communication and mobile positioning technologies makes Location-Based Services (LBSs) popular. However, because, in the LBSs, users request a query to database servers by using their exact locations, the location information of the users can be misused by adversaries. Therefore, a mechanism for users' privacy protection is required for the safe use of LBSs by mobile users. For this, we, in this paper, propose a efficient cloaking region creation scheme using Hilbert curves in distributed grid environment, so as to protect users' privacy in LBSs. The proposed scheme generates a minimum cloaking region by analyzing the characteristic of a Hilbert curve and computing the Hilbert curve values of neighboring cells based on it, so that we may create a cloaking region to satisfy K-anonymity. In addition, to reduce network communication cost, we make use of a distributed hash table structure, called Chord. Finally, we show from our performance analysis that the proposed scheme outperforms the existing grid-based cloaking method.

• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.19-30
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• 2009

Recent development in wireless communication technology and mobile equipment like PDA, cellular phone and GPS makes location-based services (LBSs) popular. However, because, in the LBSs, users continuously request a query to LBS servers by using their exact locations, privacy information could be in danger. Therefore, a mechanism for users' privacy protection is required for the safe and comfortable use of LBSs by mobile users. For this, this paper propose a grid-based cloaking area creation scheme supporting continuous LBSs. The proposed scheme creates a cloaking area rapidly by using grid-based cell expansion to efficiently support the continuous LBSs. In addition, to generate a cloaking area which makes the exposure probability of a mobile user to a minimum, we compute a privacy protection degree by granting weights to mobile users. Finally, we show from a performance analysis that our cloaking scheme outperforms the existing cloaking schemes, in terms of service time, privacy protection degree.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.151-161
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• 2009

In Location-Based Services (LBSs), users requesting a location-based query send their exact location to a database server and thus the location information of the users can be misused by adversaries. Therefore, a privacy protection method is required for using LBS in a safe way. In this paper, we propose a new cloaking region generation algorithm using grids for privacy protection in LBSs. The proposed algorithm creates a m inimum cloaking region by finding L buildings and then performs K-anonymity to search K users. For this, we make use of not only a grid-based index structure, but also an efficient pruning techniques. Finally, we show from a performance analysis that our cloaking region generation algorithm outperforms the existing algorithm in term of the size of cloaking region.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.6
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• pp.257-263
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• 2015

Recently two seismic cloaking methods of earthquake engineering have been suggested. One is the seismic wave deflection method that makes the seismic wave bend away and the other is the shadow zone method that makes an area that seismic waves cannot pass through. It is called as seismic cloaking. The fundamental principles of the seismic cloaking by variable refractive index were explained. A two-dimensional cylindrical model which was composed of 40 layers of different density and modulus was tested by numerical simulation. The center region of the model to be protected is called 'cloaked area' and the outer region of it to deflect the incoming wave is called 'cloaking area' or 'cloak area.' As the incoming surface wave is approaching to the cloaking area, the refractive index is decreasing and, therefore, the velocity and impedance are increasing. Then, the wave bends away the cloaked area instead of passing it. Three cases are tested depending on the comparison between the seismic wavelength and the diameter of the cloaked region. The advantage and disadvantage of the method were compared with conventional earthquake engineering method. Some practical requirements for realization in fields were discussed.

• Spatial Information Research
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• v.18 no.3
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• pp.53-62
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• 2010

Recent development in wireless communication technology, like GPS, and mobile equipments, like PDA and cellular phone, make location-based services (LBSs) popular. However, because, users continuously request a query to a server in the LBSs by using their exact locations, privacy information could be in danger. Therefore, a mechanism for users' privacy protection is required for the safe and comfortable use of LBSs by mobile users. For this, we, in this paper, propose a grid-based cloaking area creation scheme supporting continuous LBSs in peer-to-peer environment. The proposed scheme creates a cloaking area by using Chord protocol, so as to support the continuous LBSs in peer-to-peer environment. Finally, we show from a performance analysis that our cloaking scheme outperforms the existing cloaking schemes, in terms of service time.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.155-163
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• 2010

최근 PDA, 휴대폰과 같은 모바일 기기 및 GPS와 같은 무선 통신 기술의 발달로 인하여 위치 기반 서비스의 이용이 확산되었다. 하지만 이러한 서비스는 사용자가 도로 네트워크에서 이동하면서 자신의 위치정보를 통해 LBS 서버에 질의를 요청하기 때문에, 심각한 개인 정보 누출의 위협이 될 수 있다. 따라서 모바일 사용자의 안전하고 편리한 위치기반 서비스 사용을 위한 개인 정보 보호 방법이 필요하다. 이를 위해 본 논문에서는 도로 네트워크 거리를 고려한 사용자 정보 보호를 지원하는 cloaking 영역 설정 기법을 제안한다. 제안하는 기법은 도로 네트워크에서 효율적이고 안전한 위치기반 서비스를 지원하기 위하여, 도로 네트워크의 거리를 고려하여 cloaking 영역을 설정한다. 마지막으로 성능평가를 통해서 제안하는 기법이 cloaking 영역 및 서비스 시간 측면에서 기존 연구보다 우수함을 보인다.