Bu Sung Lee

• Nanyang Technological University

The positive impact of urban greenspace on human wellbeing is well known, as is the positive impact that urban trees have on a myriad of factors related to human health. Questions remain as to whether urban trees generally, including street trees and small stands that may not be associated with a greenspace, have an effect on a holistic measure of...

The ability to understand and predict the flows of people in cities is crucial for the planning of transportation systems and other urban infrastructures. Deep-learning approaches are powerful since they can capture non-linear relations between geographic features and the resulting mobility flow from a given origin location to a destination locatio...

For indoor localisation, a challenge in data-driven localisation is to ensure sufficient data to train the prediction model to produce a good accuracy. However, for WiFi-based data collection, human effort is still required to capture a large amount of data as the representation Received Signal Strength (RSS) could easily be affected by obstacles a...

Urban noise is becoming more serious and increasingly concerning environmental problems. This has led to numerous studies on traffic noise. However, not many studies have been done on noise from a human perspective as they go about their daily life. In another aspect, using of the crowd-sourcing platform is on the rise as the usage of personal devi...

The issue of an ever-increasing ageing population has been the increasing burden on caregivers to care for the elderly population. Caring for elders, especially those diagnosed with dementia, can be challenging. People living with dementia (PWD) require extra care and attention from the caregivers due to the associated behaviours that come with dem...

The ability to understand and predict the flows of people in cities is crucial for the planning of transportation systems and other urban infrastructures. Deep-learning approaches are powerful since they can capture non-linear relations between geographic features and the resulting mobility flow from a given origin location to a destination locatio...

Urban noise is becoming more serious and increasingly concerning environmental problems. This has led to numerous study on traffic noise. However, not much studies has been done on the noise from a human perspective as they go about their daily life. In this paper we report on the study of noise level in a campus environment, in open common areas w...

The vehicle-to-grid (V2G) concept utilises electric vehicles as distributed energy storage and thus may help to balance out the intermittent availability of renewable energy sources such as photovoltaics. V2G is therefore considered to play an important role for achieving low-carbon energy and transportation systems in cities. However, the adequate...

Ageing causes loss of muscle strength, especially on the lower limbs, resulting in higher risk to injuries during functional activities. The path to recovery is through physiotherapy and adopt customized rehabilitation exercise to assist the patients. Hence, lowering the risk of incorrect exercise at home involves the use of biofeedback for physica...

Aging causes loss of muscle strength, especially on the lower limbs, resulting in a higher risk of injuries during functional activities. To regain mobility and strength from injuries, physiotherapy prescribes rehabilitation exercise to assist the patients' recovery. In this article, the authors survey the existing work in exercise assessment and s...

As modern assistive technology advances, eye-based text entry systems have been developed to help a subset of physically challenged people to improve their communication ability. However, speed of text entry in early eye-typing system tends to be relatively slow due to dwell time. Recently, dwell-free methods have been proposed which outperform the...

News from traditional media has been used to facilitate the prediction of stock movement for a long time. However, in recent times, online social networks (OSN) have played an increasing significant role as a platform for information sharing. News content posted on these OSN provides very useful insight about public moods. In this paper, we careful...

Many current computing systems such as clouds and supercomputers charge users for their resource usages. A user's demand is often changing over time, indicating that it is difficult to keep the high resource utilization all the time for cost efficiency. Resource sharing is a classical and effective approach for high resource utilization. In view of...

Cybercriminals ramp up their efforts with sophisticated techniques while defenders gradually update their typical security measures. Attackers often have a long-term interest in their targets. Due to a number of factors such as scale, architecture and nonproductive traffic however it makes difficult to detect them using typical intrusion detection...

Cybercriminals ramp up their efforts with sophisticated techniques while defenders gradually update their typical security measures. Attackers often have a long-term interest in their targets. Due to a number of factors such as scale, architecture and nonproductive traffic however it makes difficult to detect them using typical intrusion detection...

To address the computing challenge of ’big data’, a number of data-intensive computing frameworks (e.g., MapReduce, Dryad, Storm and Spark) have emerged and become popular. YARN is a de facto resource management platform that enables these frameworks running together in a shared system. However, we observe that, in cloud computing environment, the...

Alternative form of text entry is a tremendous benefit for a subset of physically challenged people, spurning the development of many assistive technologies. However, speed of text entry with these methods is still a critical problem. Eye gaze technologies have potential for text entry, but still tend to relatively slow. Recently dwell-free eye-typ...

Over the last decades, eye gaze has become an alternative form of text entry by some physically challenged people. Recently a dwell-free system has been proposed, which has been proven to be much faster compared to other existing dwell-free systems. However, it is vulnerable to some common text entry problems. In the paper, we propose GazeTry, a dw...

Given the availability of EEG technology and existing studies, this paper discusses the feasibility of development of mobile applications controlled by brainwaves using a low-cost, non-invasive, headband type of device that collects two-channel EEG signals at frontal lobe. We have performed temporal, spectral and spatial analysis on EEG signals col...

MapReduce is a popular parallel computing paradigm for large-scale data processing in clusters and data centers. A MapReduce workload generally contains a set of jobs, each of which consists of multiple map tasks followed by multiple reduce tasks. Due to 1) that map tasks can only run in map slots and reduce tasks can only run in reduce slots, and...

This paper investigates network traffic before and after a vulnerability called Heart bleed becomes a public issue around March to May, 2014. To detect anomalies and potential threats due to the vulnerability, a wavelet entropy-based change-point detection method is proposed and compared with three other methods: prediction-based, clustering-based...

Virtualization-based Data Centers are increasingly becoming the hosting platform for a wide range of applications. The communication patterns in Data Center networks show the trend towards increasing bandwidth usage between virtual machines (VMs) within the Data Center resulting in higher chance of occurrence of network congestion. Thus, VM placeme...

Recent studies have suggested significant differences in motor performances of Parkinson's Disease (PD) patients who have L-dopa induced dyskinesias (LIDs), even when off of L-dopa medication. The pathophysiology of LIDs remains obscure, so applying data-mining techniques to the patients' motor performance may provide some heuristic insight. This p...

Generally, H.264/AVC video coding standard with hierarchical bi-predictive picture (HBP) structure outperforms the classical prediction structures such as ‘IPPP...’ and ‘IBBP...’ through better exploitation of data correlation using reference frames and unequal quantization setting among frames. However, multiple reference frames (MRFs) techniques...

Cloud computing is emerging as a promising alternative to supercomputers for some high-performance computing (HPC) applications. With cloud as an additional deployment option, HPC users and providers are faced with the challenges of dealing with highly heterogeneous resources, where the variability spans across a wide range of processor configurati...

MapReduce is a popular computing paradigm for large-scale data processing in cloud computing. However, the slot-based MapReduce system (e.g., Hadoop MRv1) can suffer from poor performance due to its unoptimized resource allocation. To address it, this paper identifies and optimizes the resource allocation from three key aspects. First, due to the p...

Fair resource allocation is a key building block of any shared computing system. However, MemoryLess Resource Fairness (MLRF), widely used in many existing frameworks such as YARN, Mesos and Dryad, is not suitable for pay-as-you-use computing. To address this problem, this paper proposes Long-Term Resource Fairness (LTRF), a novel fair resource all...

This paper presents a healthcare application that tracks body parts movement in video recording persons who exercise, analyzes the motor performance (e.g., motion speed and space), and evaluates fitness status (e.g., motion accuracy and abnormality). We design a MapReduce video processing for collecting the data of body parts movement from a large...

We propose a data center resource management framework to support green computing. This framework is composed of the power and workload management, and capacity planning schemes. While an action of power and workload management is performed in a short-term basis (e.g., fraction of minute), a decision of capacity planning is made in a long-term basi...

When faced with visual uncertainty during motor performance, humans rely more on predictive forward models and proprioception and attribute lesser importance to the ambiguous visual feedback. Though disrupted predictive control is typical of patients with cerebellar disease, sensorimotor deficits associated with the involuntary and often unconsciou...

SUMMARY High availability of software components has long been studied. For a software system, when unavailability of a component has caused a suspension of the system, the system has to be recovered or resumed as soon as possible. To substitute an unavailable software component with a backup copy is therefore unavoidable in achieving high availabi...

Cloud computing is emerging as an alternative to supercomputers for some of the high-performance computing (HPC) applications that do not require a fully dedicated machine. With cloud as an additional deployment option, HPC users are faced with the challenges of dealing with highly heterogeneous resources, where the variability spans across a wide...

Simulation has become an important method that is widely used in studying the propagation behaviors during the process of viral advertisement diffusion. With the increased computing and memory resources required for large-scale network processing, General Purpose Graphics Processing Units (GPGPUs) have been used in high performance computing platfo...

The use of Software-Defined Networking (SDN) with OpenFlow-enabled switches in Data Centers has received much attention from researchers and industries. One of the major issues in OpenFlow switch is the limited size of the flow table resulting in evictions of flows from the flow table. From Data Center traffic characteristics, we observe that eleph...

Hadoop, based on the popular MapReduce framework, is an open‐source distributed computing framework that has been gaining much popularity and usage. It aims to allow programmers to focus on building applications that deals with processing large amount of data, without having to handle other issues when performing parallel computations. However, tun...

General Purpose Graphics Processing Units (GPGPU) have been used in high performance computing platforms to accelerate the performance of scientific applications such as simulations. With the increased computing resources required for large-scale network simulation, one GPU device may not have enough memory and computation capacities. It is therefo...

MapReduce is a popular parallel computing paradigm for large-scale data processing in clusters and data centers. However, the slot utilization can be low, especially when Hadoop Fair Scheduler is used, due to the pre-allocation of slots among map and reduce tasks, and the order that map tasks followed by reduce tasks in a typical MapReduce environm...

MapReduce has become a widely used computing model for large-scale data processing in clusters and data centers. A MapReduce workload generally contains multiple jobs. Due to the general execution constraints that map tasks are executed before reduce tasks, different job execution orders in a MapReduce workload can have significantly different perf...

In this paper, we propose a power-efficient solution for virtual machine placement and migration in a fat tree data center network. This solution reduces power consumption as well as job delay by aggregating virtual machines to a few hyper visors and migrating communicating parties to close locations. In this work, we consider OpenFlow as the imple...

The existing video coding standard H.264 could not provide expected rate-distortion (RD) performance for the macroblocks (MBs) with both moving objects and static background and the MBs with uncovered background (previously occluded). The pattern-based video coding (PVC) technique partially addresses the first problem by separating and encoding mov...

The inability to effectively track data in cloud computing environments is becoming one of the top concerns for cloud stakeholders. This inability is due to two main reasons. Firstly, the lack of data tracking tools built for clouds. Secondly, current logging mechanisms are only designed from a system-centric perspective. There is a need for data-c...

The limitation of existing wireless wide area networks, coupled with the delay tolerant property of many non-realtime applications (e.g. email, file download) enables drive-thru networking, which depends on roadside units (RSUs) to provide vehicular users with intermittent Internet access service. Focusing on the downlink service, MaxCD – a joint m...

This paper studies event recognition in a building based on the patterns of power consumption. It is a big challenge to identify what kinds of events happened in a building without additional devices such as camera and motion sensors, etc. Instead, we learn when and how the events happened from the historical record of power consumption and apply t...

Motion estimation (ME) and motion compensation (MC) using variable block size, sub-pixel search, and multiple reference frames (MRFs) are the major reasons for improved coding performance of the H.264 video coding standard over other contemporary coding standards. The concept of MRFs is suitable for repetitive motion, uncovered background, non-inte...

This paper proposes a Hybrid Protocol for Application Level Multicast with Dual Metric (HPAM-D) for live video streaming. HPAM-D constructs data distribution trees based on two performance metrics, namely, latency to source and loss rate experienced by the clients. The protocol is evaluated against the latency based single-metric HPAM and a modifie...

We focus on the problems of cooperative virtual machine management of cloud users in a smart grid environment. In such an environment, the cloud users can cooperate to share the available computing resources in private cloud and public cloud to reduce the total cost. To achieve an optimal and fair solution, we develop the framework composed of the...

Simulations provide a flexible and valuable method to study the behaviors of information propagation over complex social networks. High Performance Computing (HPC) is a technology that allows the implementation of efficient algorithms on powerful new hardware resources. With the increased computing resource usage in large-scale network based simula...

Version control systems are an indispensable part of the software engineering process. Without them, large software development projects would soon incur in loss of productivity and severe maintenance issues. The revision history is invaluable during reviewing process as well as bug hunting. With the advent of Web 2.0, many tasks have been migrated...

This paper proposes a multi-tenant workflow framework that allows users to create data analytic workflows whose tasks are efficiently scheduled and distributed in cloud computing environment. We provide a demo of an event room assignment (ERA) as a test application of the framework. The ERA dynamically and automatically assigns registered events (e...

This paper reports on the development of the Cloud Oriented Data Analytics (CODA) framework which has functions for composing, managing, and processing workflows for data analytics in cloud computing. The framework provides a number of reusable software components for data analytics to users which can be composed as workflows through well-known wor...

Many private and/or public organizations have been reported to create and monitor targeted Twitter streams to collect and understand users' opinions about the organizations. Targeted Twitter stream is usually constructed by filtering tweets with user-defined selection criteria e.g. tweets published by users from a selected region, or tweets that ma...

It is highly desirable and challenging for a wireless ad hoc network to have self-organization properties in order to achieve wide network characteristics. Studies have shown that Small-World properties, primarily low average path length (APL) and high clustering coefficient, are desired properties for networks in general. However, due to the spati...

In this paper, we address the energy-efficient contact discovery issue in Pocket Switched Networks (PSNs), in which the nodes' mobility pattern shows strong social property. In a PSN, although the end-to-end connection may be disconnected most of the time for a given source-destination pair, several nodes periodically gather at certain hot spots an...

In this paper we propose MaxCD - a joint multi-flow scheduling and cooperative downloading protocol for drive-thru networks, with the goal of maximizing the amount of data packets that can be downloaded per drive-thru. Based on the macro-level opportunistic scheduling and node cooperation, the best wireless link(s) (with the highest data rate) betw...

We propose an adaptive power management (APM) algorithm for a data center with an objective to minimize the total cost of power bought from an electrical grid. This APM algorithm is developed for a smart grid environment which is envisioned to be a cooperative, responsive, and economical power system. In particular, APM algorithm takes the spot pow...

The fast growth of cloud service offerings has attracted more enterprises to migrate their IT applications into cloud. Nonetheless, complex enterprise user requirements, especially interdependent relations across them, raise new challenges of cloud service selection. In addition, a major concern for these enterprises is ensuring compliance with the...

Data leakages out of cloud computing environments are fundamental cloud security concerns for both the end-users and the cloud service providers. A literature survey of the existing technologies revealed the inadequacies of current technologies and the need for a new methodology. This position paper discusses the requirements and proposes a novel a...

This paper presents a scheme to optimize the mapping of HPC applications to a set of hybrid dedicated and cloud resources. First, we characterize application performance on dedicated clusters and cloud to obtain application signatures. Then, we propose an algorithm to match these signatures to resources such that performance is maximized and cost i...

As cloud computing and virtualization technologies become mainstream, the need to be able to track data has grown in importance. Having the ability to track data from its creation to its current state or its end state will enable the full transparency and accountability in cloud computing environments. In this paper, we showcase a novel technique f...

As REST (Representational State Transfer)-ful services are closely coupled to the HTTP (Hypertext Transfer Protocol), which eventually sits above the connection-based TCP (Transmission Control Protocol), it is common for RESTful services to experience latency and transfer inefficiencies especially in situations requiring the services to transfer la...

Mobile cloud computing enables numerous associated mobile users to access the abundant cloud computing resources, thereby complements the resource constrain of mobile devices. A fundamental issue in the mobile application platform is to make deployment decision for individual tasks when the battery life of the mobile device is a major concern for t...

This paper studies a cloud computing market where a cloud provider rents a set of computing resources from Windows Azure operated by Microsoft. The cloud provider can integrate value-added services to the resources. Then, the services can be sold to customers, and the cloud provider can earn a profit. Moreover, the cloud provider could save much co...

Semantic Web efforts aim to bring the WWW to a state in which all its content can be interpreted by machines; the ultimate goal being a machine-processable Web of Knowledge. We strongly believe that adding a mechanism to extract and compute concepts from the Semantic Web will help to achieve this vision. However, there are a number of open question...

In H.264/advanced video coding (AVC), lossless coding and lossy coding share the same entropy coding module. However, the entropy coders in the H.264/AVC standard were original designed for lossy video coding and do not yield adequate performance for lossless video coding. In this paper, we analyze the problem with the current lossless coding schem...

In this paper, we present our design of a Processing Element (PE) Aware MapReduce base framework, Pamar. Pamar is designed for supporting distributed computing on clusters where node PE configurations are asymmetric on different nodes. Pamar's main goal is to allow users to seamlessly utilize different kinds of processing elements (e.g., CPUs or GP...

Load balancing is a challenging work for parallel dynamic programming due to its intrinsically strong data dependency. Two issues are mainly involved and equally important, namely, the partitioning method as well as scheduling and distribution policy of subtasks. However, researchers take into account their load balancing strategies primarily from...

This paper studies the speedup for multi-level parallel computing. Two models of parallel speedup are considered, namely, fixed-size speedup and fixed-time speedup. Based on these two models, we start with the speedup formulation that takes into account uneven allocation and communication latency, and gives an accurate estimation. Next, we propose...

Multiple description coding (MDC) is one of the widely used mechanisms to combat packet-loss in non-feedback systems. However, the number of descriptions in the existing MDC schemes is very small (typically 2). With the number of descriptions increasing, the coding complexity increases drastically and many decoders would be required. In this paper,...

Motivated by the benefits of small world networks, we propose a self-organization framework for wireless ad hoc networks. We investigate the use of directional beamforming for creating long-range short cuts between nodes. Using simulation results for randomized beamforming as a guideline, we identify crucial design issues for algorithm design. Our...

The Bio Sequence alignment involves arranging DNA, RNA or protein sequences in order to find similarity between the aligned sequences, which helps us to find the structural, functional and evolutionary relationships among organisms. Next generation sequencing has led to the generation of billions of sequence data, making it increasingly infeasible...

With the wide applications of saliency information in visual signal processing, many saliency detection methods have been proposed. However, some key characteristics of the human visual system (HVS) are still neglected in building these saliency detection models. In this paper, we propose a new saliency detection model based on the human visual sen...

In places where mobile users can access multiple wireless networks simultaneously, a multipath scheduling algorithm can benefit the performance of wireless networks and improve the experience of mobile users. However, existing literature shows that it may not be the case, especially for TCP flows. According to early investigations, there are mainly...

This paper addresses the problem of delivering data packets for highly dynamic mobile ad hoc networks in a reliable and timely manner. Most existing ad hoc routing protocols are susceptible to node mobility, especially for large-scale networks. Driven by this issue, we propose an efficient Position-based Opportunistic Routing (POR) protocol which t...

The standardization of cloud services makes it possible to have one cloud service management platform for customers to take advantage of their subscriptions from various cloud providers. One immediate benefit lies in the way that enterprise customers may have plenty of choices of available providers, when seeking cloud services to fulfill their cri...

The Entropy coding module in the H.264/advanced video coding (AVC) standard was originally designed for lossy video coding and does not yield adequate performance for lossless video coding. In this paper, we analyze the problem with the current lossless coding scheme and therefore propose a Coefficients Reordering based method for H.264/AVC lossles...

E-learning systems are now considered a core IT support in most Institute of Higher Learning. Each student is assigned a set of courses based on their preferences for each semester. Learning materials are posted and evaluated through the system. Mining access and usage log data of the e-learning system can give insights such as on how these materia...

H.264/AVC FRExt (Fidelity Range Extensions) and Motion JPEG 2000 are the current respective inter-frame and intra-frame coding standards for high resolution (HR) (e.g., 4096×2160) visual signals. It is commonly believed that an inter-frame method could achieve higher coding efficiency compared with an intra-frame one, due to the exploitation of vid...

Provenance, a meta-data describing the derivation history of data, is crucial for the uptake of cloud computing to enhance reliability, credibility, accountability, transparency, and confidentiality of digital objects in a cloud. In this paper, we survey current mechanisms that support provenance for cloud computing, we classify provenance accordin...

Cloud computing service providers offer cost-effective means to burst computational needs and utilise live migration of virtual machines (VMs) for effective and efficient work-load movements with short service downtimes. However, there is a lack of support for migrating VMs between different service providers as well as private and public cloud off...

Trust is one of the main obstacles to widespread Cloud adoption. In order to increase trust in Cloud computing, we need to increase transparency and accountability of data in the Cloud for both enterprises and end-users. However, current system tools are unable to log file accesses and transfers effectively within a Cloud environment. In this paper...

An emerging class of technologies defined as Service-Oriented Architecture (SOA) has been heralded as the answer for inflexible IT architecture and promises to reduce operational barriers of current IT infrastructures. In SOA, loosely coupled Web services are integrated to provide dynamic digital capabilities within and across enterprise boundaries...

Existing literature has looked to exploit wireless broadcast advantage (WBA) in order to optimize the performance of a wide variety of network operations. In this paper, we obtain a measure of WBA in a multihop scenario. We consider that all nodes in the network store and propagate implicitly received information from neighbourhood transmissions, r...

Cloud Computing has become more and more prevalent over the past few years, and we have seen the emergence of Infrastructure-as-a-Service (IaaS) which is the most acceptable Cloud Computing service model. However, coupled with the opportunities and benefits brought by IaaS, the adoption of IaaS also faces management complexity in the hybrid cloud e...

In an autonomous wireless sensor network, self-organization of the nodes is essential to achieve network wide characteristics. We believe that connectivity in wireless autonomous networks can be increased and overall average path length can be reduced by using beamforming and bio-inspired algorithms. Recent works on the use of beamforming in wirele...

We study how long range directional beams can be used for self-organization of a wireless network to exhibit small world properties. Using simulation results for randomized beamforming as a guideline, we identify crucial design issues for algorithm design. Subsequently, we propose an algorithm for deterministic creation of small worlds. We define a...

In video coding, an intra (I-) frame is used as an anchor frame for referencing the subsequence frames, as well as error propagation prevention, indexing, etc. To get better rate-distortion performance, a frame should have the following quality to be an ideal I-frame: the best similarity with the frames in a group of picture (GOP), so that when it...

We look at the problem of network wide broadcast using the multi-rate feature of a wireless ad hoc network. Existing research has primarily focused on achieving minimum latency by construction of minimum weight connected dominating sets (WCDS) based on neighbourhood information. In this paper, we are interested in stateless multi-rate broadcasting...

In this paper, we propose a low-complexity video coding scheme based upon 2-D singular value decomposition (2-D SVD), which exploits basic temporal correlation in visual signals without resorting to motion estimation (ME). By exploring the energy compaction property of 2-D SVD coefficient matrices, high coding efficiency is achieved. The proposed s...