MoonBae Song

Korea University | KU · Department of Computer and Information Science

Wi-Fi received signal strength (RSS) fingerprint-based indoor positioning has been widely used because of its low cost and universality advantages. However, the Wi-Fi RSS is greatly affected by multipath interference in indoor environments, which can cause significant errors in RSS observations. Many methods have been proposed to overcome this issu...

Academic discussions on cultural intelligence (CQ) are now paying attention to their potential utilization from various angles. The field of study is expanded not only in business administration but also in psychology, education, tourism, communication, and arts. This is due to the widespread study of global communication competence in multicultura...

To receive location‐based services (LBS), users must disclose their locations and queries to the LBS server, which can expose the user's identity, location, and other information. Recently, techniques for protecting user privacy using dummies have been researched. However, many factors, such as the distance between the obstacles and the dummies, mu...

An increasing amount of active research is being conducted to protect the locations of mobile device users. Users must tune to more data than they would like to in order to hide their location. In particular, if a user requests a query over k NN, the number of objects the user must receive may increase. Several studies have been proposed to solve t...

Despite of various benefits such as a convenience and efficiency, home healthcare systems have some inherent security risks that may cause a serious leak on personal health information. This work presents a Secure User Profiling Structure which has the patient information including their health information. A patient and a hospital keep it at that...

Recently, monitoring queries are getting attention for various real-life applications such as safety, security, and personalization services. This work proposes a distributed sensing and monitoring technique (called Sleepwalk ) for continuous range queries with energy- and computation-efficient optimizations. In our scheme, each mobile client (MC)...

A content-matched (CM) rangemonitoring query overmoving objects continually retrieves the moving objects (i) whose non-spatial attribute values are matched to given non-spatial query values; and (ii) that are currently located within a given spatial query range. In this paper, we propose a new query indexing structure, called the group-aware query...

To protect users’ private locations in location-based services, various location anonymization techniques have been proposed. The most commonly used technique is spatial cloaking, which organizes users’ exact locations into cloaked regions (CRs). This satisfies the K -anonymity requirement; that is, the querier is not distinguishable among K users...

In this paper, we propose AMV scheme which supports k-anonymization by using vectors for mobile clients. AMV can produces the minimal cloaking area using motion vector information of users (clients). The main reason for minimizing cloaking area is a server has to send the object information to all users who request the spatial queries. The experime...

Professor Marreiros reviews “Context-aware adaptation of component-based systems: an active repository approach” which proposes context-aware adaptation technique for component-based software (CBS) systems. In this paper, the authors propose an active component repository that is able to receive the current configuration and components from the con...

Supporting high update throughput is important to provide real-time location information for many applications, which involve moving objects, such as security, military, and environmental monitoring. We present an R-tree-based index structure with a family of update strategies for supporting high update throughput. It groups updates in the update b...

Due to the fact that most of the sensor network applications are based on the location information of sensor nodes, localization is an essential research area. Some localization schemes in the literature require sensor nodes to have additional devices to measure the distance or angle between two sensor nodes, but it is not suitable for low-cost sen...

Managing frequent updates is greatly important in many update-intensive applications, such as location-aware services, sensor networks, and stream databases. In this paper, we present an R-tree-based index structure (called Rsb-tree, R-tree with semibulk loading) for efficiently managing frequent updates from massive moving objects. The concept of...

Recently, ubiquitous location-based services (u-LBS) has been utilized in a variety of practical and mission-critical applications such as security services, personalization services, location-based entertainment, and location-based commerce. The essence of u-LBS is actually the concept of location-awareness where location-aware devices perform mor...

As a de facto standard protocol, Internet protocol security (IPSec) provides secure communication between networked systems. One of the most common issues today in large-scale virtual private networks using IPSec is the problem of a stale security association, which occurs when the device at one end of the tunnel maintains the tunnel state but the...

This letter proposes a group-based distributed air index (called GDI) using two-leveled groups by partitioning the identifiers of data items to reduce the size of the index. GDI provides both global and local views of data items and multiple pointers to data items in a single access to an index. Simulation results show that GDI outperforms the exis...

A new nearest neighbor (NN) search algorithm for R-trees was proposed that performed in a bottom-up manner. The proposed approach starts at the leaf level and traverses to the Root node. The experimental results demonstrate that the proposed NN search algorithm outperforms existing NN search algorithms which are based on the R-tree including the ex...

This paper addresses the problem of monitoring continuous k-nearest neighbor (k-NN) queries. In order to support highly dynamic environments, where objects and/or queries are frequently moving, monitoring continuous k-NN require real-time updated results when objects and/or queries change their locations. Thus, it is important to minimize time dela...

To facilitate power saving via wireless data broadcast, index information is typically broadcast along with the data. By first accessing the broadcast index, the mobile client is able to predict the arrival time of the desired data. However, it suffers from the drawback that the client has to wait and tune for an index segment, in order to conserve...

In mobile computing, a huge number of users expect various data services based on their location. Wireless data broadcast is suitable for meeting requests from lots of users owing to its scalability. Air indexing techniques have been developed for energy efficient query processing of mobile clients in the wireless data broadcast. Especially for spa...

Broadcasting is the natural method of propagating information in wireless links, which guarantees scalability in the case of bulk data transfers. It is particularly attractive for resource limited mobile clients in asymmetric communications. To facilitate power saving via wireless data broadcast, index information is typically broadcast along with...

There are two principal aspects of “mobility” in location-aware computing: (1) how to support mobility and (2) how to exploit it. This paper considers the latter, while many existing works only concentrate on the former. This work is trying to prove that the performance of location-aware systems will be greatly improved by understanding the user's...

This paper proposes a generic framework for continuous range queries via wireless data broadcast. This framework distinguishes itself from existing work by being the first to address the continuous spatial query issue, without an index, making effective use of the low wireless bandwidth, and therefore being ideal for achieving maximal scalability w...

Given a query point q, finding the nearest neighbor (NN) object is one of the most important problem in computer science. In this paper, a bottom-up search algorithm for processing NN query in R-trees is presented. An additional data structure, hash, is introduced to increase the pruning capability of the proposed algorithm. Based on hash, whole da...

Wireless data broadcast, which allows simultaneous access by an arbitrary number of clients, is a very efficient and scalable information dissemination method. It is particularly attractive for resource limited mobile clients in asymmetric communications. In Location Dependent Information Services(LDISs), it is important to reduce the query respons...

Air indexing techniques have been developed for energy efficient query processing of mobile clients(MCs) in the wireless data broadcast. In the air indexing for spatial data, previous studies have involved various problems, long broadcast cycle by large index size and unnecessary data listening by the query processing based on coordinates, which ar...

This paper presents a novel analytical approach to evaluate the signaling load of Mobile IPv6 (MIPv6) and Hierarchical Mobile IPv6 (HMIPv6). Previous analytical approaches for IP mobility management have not provided a complete and general framework for the performance analysis; no consideration of either periodic binding refresh cost or extra pack...

The “mobility” has two important aspects: i) how to support mobility and ii) how to exploit mobility. This paper considers the latter, while many existing works only consider the former. This work is trying to prove that system performance will be greatly improved by understanding a user’s movement. In this paper, we propose a novel location update...

To conserve the usage of energy, indexing techniques have been developed in a wireless mobile environment. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, we present the broadcast-based location dependent data delivery scheme (BBS) for dynamic range queries. In...

Location-aware mobile services(LAMSs) are characterized by a large number of objects and a large number of queries. Moreover, with a large candidate data set, answering LAMSs via scanning through the whole data set becomes extremely expensive. In broadcast-based services, any number of clients can monitor the broadcast channel and retrieve the data...

Indexing techniques have been developed for wireless data broadcast environments, in order to conserve the scarce power resources of the mobile clients. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, the broadcast-based spatial query processing methods (BBS) a...

The Voronoi Diagram(VD) is the most suitable mechanism to find the nearest neighbor(NN) for mobile clients. In NN query processing, it is important to reduce the query response time, since a late query response may contain out-of-date information. In this paper, we study the issue of location dependent information services(LDISs) using a VD. To beg...

Indexing techniques have been developed for wireless data broadcast environments, in order to conserve the scarce power resources of the mobile clients. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, we present the broadcast-based spatial query processing algo...

Indexing techniques are used to implement selective tuning in wireless environments. Indices are broadcast together with data to help mobile clients locate the required information. As a result, clients stay in doze mode most of the time. The drawback of this solution is that broadcast cycles are lengthened due to additional index information. In t...

The issue of standardized generation scheme of spatio- temporal datasets is a research area of growing importance. In case of the lack of large real datasets, especially, benchmarking spatio-temporal database requires the generation of synthetic datasets simulating the real-word behavior of spatial objects that move and evolve over time. Recently,...

In mobile computing environments, location plays an important role in determining user's interests. If service providers can supply information reflecting users' semantics, overall system performance can be improved. Users can avoid queries, resulting in unnecessary network usage. A query result can also be transferred to a local device. Through ou...

The battery, in contrast to other hardware, is not governed by Moore's Law. In location-aware computing, power is a very limited resource. As a consequence, recently, a number of promising techniques in various layers have been proposed to reduce the energy consumption. The paper considers the problem of minimizing the energy used to track the loca...

Location dependent information services (LDISs) produce answers to queries according to the location of the client issuing the query. In LDIS, techniques such as caching, prefetching and broadcasting are effective approaches to reducing the wireless bandwidth requirement and query response time. However, the client’s mobility may lead to inconsiste...

The results of location-dependent queries(LDQ) generally depend on the current locations of query issuers. Many mechanisms, such as broadcast scheme, prefetching scheme, or caching scheme have been developed to improve system performance and provide better service for location dependent information services(LDISs). However, the client’s mobility ma...

One of the most important issues in location-based services is tracking moving ob- jects efficiently. To achieve this goal, an efficient protocol which updates location in- formation in a location server is primarily needed. In fact, the performance of a location update strategy highly depends on the assumed mobility pattern. In most existing studi...

What is important in location-aware services is how to track moving objects efficiently. To this end, an efficient protocol which updates location information in a location server is highly needed. In fact, the performance of a location update strategy highly depends on the assumed mobility pattern. In most existing works, however, the mobility iss...

In mobile computing environments, mobility plays an important role in data management issues inherently. In most existing works, however, the mobility issue has been disregarded and too simplified as linear function of time. In this paper, we propose a new dynamic state transition model, namely state-based mobility model (SMM) to provide more gener...

In this paper, a new variable ordering algorithm, distributed reordering algorithm that allows more faster solution than existing ones, is presented. Since this method can accomplish fast optimization of BDD in less memory and computation time, the proposed algorithm is more efficient for dynamic variable ordering. Also, the proposed algorithm can...