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

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.8
• /
• pp.1155-1160
• /
• 2013

The rapid growth of smart phones has made location-based services (LBSs) widely available. However, the use of LBS can raise privacy issues, as LBS can allow adversaries to violate the location privacy of users. There has been a considerable amount of research on preserving user location privacy. Most of these studies try to preserve location privacy by achieving what is known as location K-anonymity. In this paper, we propose a hierarchical clustering-based spatial cloaking algorithm for LBSs. The proposed algorithm constructs a tree using a modified version of agglomerative hierarchical clustering. The experimental results show, in terms of the ASR size, that the proposed algorithm is better than Hilbert Cloak and comparable to RC-AR (R-tree Cloak implementation of Reciprocal with an Asymmetric R-tree split). In terms of the ASR generation time, the proposed algorithm is much better in its performance than RC-AR and similar in performance to Hilbert Cloak.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.1
• /
• pp.63-71
• /
• 2013

In order to support mobility for sink groups, it is important to get the current location of a mobile sink group and then to offer the location to a source. Typically, previous works calculate a region including all member sinks by flooding; then, it notifies this region information to a source. However, flooding and location updates are periodically performed regardless of the group movement so that it causes considerable control overhead. In this paper, we propose an energy-efficient scheme supporting mobile sink groups. The proposed scheme obtains a location of a group without flooding. It exploits the inherent property of mobile sink groups which could approximate entire group movement by only partial member sinks movement. Also, the scheme learns group location by back-propagation learning method through exploiting overhearing feature in wireless communication environment. Our simulation studies show that the proposed scheme significantly improves in terms of energy consumption compared to the previous work.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.451-458
• /
• 2011

In order to provide the optimal location based services such as the optimal moving path search or the scheduling pattern prediction, the extraction of significant moving pattern which is considered the temporal and spatial properties of the location-based historical data of the moving objects is essential. In this paper, for the extraction of significant moving pattern we propose the location generalization method which translates the location attributes of moving object into the spatial scope information based on $R^*$-tree for more efficient patterning the continuous changes of the location of moving objects and for indexing to the 2-dimensional spatial scope. The proposed method generates the moving sequences which is satisfied the constraints of the time interval between the spatial scopes using the generalized spatial data, and extracts the significant moving patterns using them. And it can be an efficient method for the temporal pattern mining or the analysis of moving transition of the moving objects to provide the optimal location based services.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.3
• /
• pp.499-505
• /
• 2016

In this Paper, we propose a body-area localization technique based on WUSB (Wireless USB) over WBAN (Wireless Body Area Networks) protocol required for wearable computer systems. The proposed localization algorithm is executed on the basis of WUSB over WBAN protocol at each sensor node comprising peripherals of a wearable computer system. To increase the accuracy of input information through various body motions in wearable computer systems, a new localization technique with high precision must be developed. To achieve the goal, This paper proposes a combined TDoA/FDoA/AoA (Time Of Arrival/Time Difference Of Arrival/Angle Of Arrival) localization technique with more than four WUSB over WBAN devices to estimate body-area location accurately. The combined TDoA/FDoA/AoA technique reduces 10mm in location estimation errors comparing with a combined TDoA/FDoA technique. This performance enhancement in location error reduction can be ignored at other systems but is meaningful results in body-area localization-based communications.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.7B
• /
• pp.595-601
• /
• 2006

This study presents an ultrasonic location awareness system for the ubiquitous computing with absolute position. The flight time of ultrasonic waves is determined by a period detecting technique which is able to extend the sensing range compared with traditional methods. For location awareness, ultrasonic waves are sent successively from each ultrasonic transmitter and synchronized by radio frequency (RF) signal, where the transmitting part is fixed and the receiving part is movable. To expand the recognizing range, cell matching technique and coded ultrasonic technique are introduced. The experimentation for various distances is accomplished to verify the used period detecting technique of U-SAT system. The positioning accuracy by using cell matching is also verified by finding the locations of settled points and the usability of coded ultrasonic technique is verified. As a result, the possibility of ultrasonic location awareness system for the ubiquitous computing can be discussed as a pseudo-satellite system with low cost, a high update rate, and relatively high precision, in the places where GPS is not available.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.7
• /
• pp.93-101
• /
• 2020

Regional CRL(certificate revocation list) in vehicular communications is to partition Full CRL into several small CRLs according to geographic location to keep the size of individual CRLs with smaller. However, since a Regional CRL includes vehicle's revoked certificates within its administrative region, it has to know vehicle' location. For this, how to know vehicle' location effectively corresponding to every region represents a major challenge. This paper proposes a Regional CRL scheme which is envisioned to achieve vehicle's location and to make regional CRLs according to vehicles current location efficiently. The scheme is based on the short-lived pseudonyms defined by WAVE standard. It also acquires issued pseudonyms, vehicle's id and region information whenever a vehicle initiates pseudonyms refill after that, utilizes them to create and distribute the Regional CRL. To keep location privacy-preserving for vehicles, the scheme uses the blockchain technology in the network. The analysis results show that it reduces CRL size and database query time for finding revoked certificates sharply in the vehicle's on-board unit.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2002.05c
• /
• pp.361-364
• /
• 2002

번호판 인식 시스템은 일반적으로 한 차선에 한 카메라를 사용한다. 만약 2개의 차로를 동시에 촬영하도록 카메라를 설치한다면 시스템 구축 비용이 많이 감소할 것이다. 본 논문은 이러한 시스템의 구축에 필요한 기본적인 방법으로써 이미지에서 번호판이 2개 이상 존재할 경우에도 그 위치를 모두 검출할 수 있는 방법에 대하여 제안한다. 번호판 후보 영역 추출은 모폴로지 연산을 통해 검출하고 각 후보 영역은 이진화후 제안한 검증 방법을 통해 후보 영역을 제거하고 번호판인 후보 영역에 대하여 정확한 번호판 영역을 검출한다. 제안한 검출 방법은 일반 번호판과 영업용 번호판 모두 검출할수 있다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2017.06a
• /
• pp.123-126
• /
• 2017

UWV(Ultra Wide View) 미디어 전송 시 서버의 부하를 줄이고 단말기의 자원 소모를 줄이기 위해서는 사용자의 관심 영역만을 제공해야 한다. 즉, 사용자가 원하는 범위의 영상들을 선택할 수 있도록 영상들의 공간적 위치정보를 제공하는 기술이 필요하다. 본 논문에서는 MMT(MPEG Media Transport)의 CI(Composition Information) 문서를 이용하여 UWV 를 구성하는 미디어들의 공간적 위치정보를 전송하고, 사용자에게 관심 영역의 미디어들을 제공하는 기법을 제안한다. 이를 위해 서버가 사용자에게 미디어들의 화면 구성에 대한 공간적 정보와 재생에 필요한 시간적 정보를 MMT CI 문서에서 제공한다. 그리고 사용자의 관심 영역을 서버로 전송하기 위한 Signaling Message 를 정의한다. 서버는 본 논문의 기법을 통해 MMT 를 그대로 사용하면서 사용자에게 관심 영역의 미디어들을 제공할 수 있다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2011.06a
• /
• pp.65-68
• /
• 2011

최근 무선 통신 기술의 발달 및 모바일 기기의 발달로 인하여 위치 기반 서비스가 주목을 받고 있다. 그러나 사용자의 정확한 위치정보를 통해 LBS 서버에 질의를 요청하는 것은 심각한 개인 정보 누출의 위협이 될 수 있기 때문에, 사용자 정보 보호를 위해 도로 네트워크를 고려하여 질의영역을 생성하는 연구가 활발히 진행되어 왔다. 따라서 질의영역에 대한 효율적인 질의 처리 방법이 요구된다. 이를 위해, 본 논문에서는 도로 네트워크에서 사용자 정보 보호를 지원하는 질의영역에 대한 k최근접점 질의 처리 알고리즘을 제안한다. 제안하는 기법은 POI를 효율적으로 검색하기 위하여 Island 인덱스를 사용한다. 또한, 본 논문은 질의 처리 성능을 향상시키기 위해 적응적 Island 인덱스를 생성하는 방법을 제안한다. 마지막으로, 성능평가를 통해 제안하는 기법이 기존 기법들에 비해 네트워크 확장 비용 및 서비스 시간 측면에서 우수함을 보인다.