Heonchang Yu

• Korea University

Edge computing reduces the response time of real-time services with handling dynamic traffics reliably. Edge servers with limited resources often utilize container technology, which provides a lightweight execution environment. When deploying containers on edge servers, a container image is required and it is predominantly downloaded from a remote...

Edge computing reduces the response time of real-time services with handling dynamic traffics reliably. Edge servers with limited resources utilize container technology that provides a lightweight execution environment. When deploying containers in edge servers, a container image is required and is downloaded from a remote registry. Therefore, thes...

Multiple containers running scientific workflows in SMP-based high-performance computers generate some bottlenecks due to workload flexibility. To improve system resource utilization by minimizing these bottlenecks, vertical resource management is required to determine an appropriate resource usage policy according to the resource usage type of the...

As the size of text documents based on cloud storage increases, the time and cost of string search and keyword search increase. However, when searching for words or sentences in documents, most string search algorithms do not take the lexical structure used in the real world, or the constitutional characteristics of the character, into account. In...

The development of IT technology in the 21st century has created a new paradigm for real-time, data-intensive user services, such as connected cars, smart factories, and remote health care services. The considerable computational resources required by these services are rendering the cloud increasingly more important. In the cloud server, user serv...

In remote procedure call (RPC)-based graphic processing unit (GPU) virtualization environments, GPU tasks requested by multiple-user virtual machines (VMs) are delivered to the VM owning the GPU and are processed in a multi-process form. However, because the thread executing the computing on general GPUs cannot arbitrarily stop the task or trigger...

With the evolution of cloud technology, the number of user applications is increasing, and computational workloads are becoming increasingly diverse and unpredictable. However, cloud data centers still exhibit a low I/O performance because of the scheduling policies employed, which are based on the degree of physical CPU (pCPU) occupancy. Notably,...

Applications with large-scale data are processed on a distributed system, such as Spark, as they are data- and computation-intensive. Predicting the performance of such applications is difficult, because they are influenced by various aspects of configurations from the distributed framework level to the application level. In this paper, we propose...

High-performance computing (HPC) uses many distributed computing resources to solve large computational science problems through parallel computation. Such an approach can reduce overall job execution time and increase the capacity of solving large-scale and complex problems. In the supercomputer, the job scheduler, the HPC’s flagship tool, is resp...

Graphics processing unit (GPU) virtualization technology enables a single GPU to be shared among multiple virtual machines (VMs), thereby allowing multiple VMs to perform GPU operations simultaneously with a single GPU. Because GPUs exhibit lower resource scalability than central processing units (CPUs), memory, and storage, many VMs encounter reso...

In the virtualization environment, a hypervisor scheduler determines the degree of shared resource occupancy of the virtual machine (VM) according to the degree of CPU processing and it provides a fair CPU processing on virtual machines (VMs). But VMs are experiencing unfair network performance due to the hypervisor scheduler’s policy occupying res...

In this study, we consider an edge cloud server in which a lightweight server is placed near a user device for the rapid processing and storage of large amounts of data. For the edge cloud server, we propose a latency classification algorithm based on deadlines and urgency levels (i.e., latency-sensitive and latency-tolerant). Furthermore, we desig...

Over the years, parallel computing models have been proposed to solve large-scale application problems. P2P and cloud computing are well-known distributed computing models and have the advantage of running and implementing the parallel computing. Applying the advantages of both models can enhance the benefits of parallel computing. In this paper, w...

As the size of data increases and computation becomes complicated in fog computing environments, the need for highperformance computation is increasing. One of the most popular ways to improve the performance of a virtual machine (VM) is to allocate a graphic processing unit (GPU) to the VM for supporting general purpose computing on graphic proces...

In this paper, we present an effective and efficient Byzantine-resilient dual membership management technique in cloud environments, in which nodes are prone to churn and the network topology is not fully connected. Our method is based on unstructured message communication model, namely a gossip protocol that is able to handle the dynamic behavior...

Many artificial intelligence applications often require a huge amount of computing resources. As a result, cloud computing adoption rates are increasing in the artificial intelligence field. To support the demand for artificial intelligence applications and guarantee the service level agreement, cloud computing should provide not only computing res...

Since cloud computing provides computing resources on a pay per use basis, a task scheduling algorithm directly affects the cost for users. In this paper, we propose a novel cloud task scheduling algorithm based on ant colony optimization that allocates tasks of cloud users to virtual machines in cloud computing environments in an efficient manner....

Since advent of information revolution, there have been a lot of interest at big data analytics as well as big data. In the big data analytics, it is essential that not only extracting valuable information from the big data but also processing the data rapidly. Therefore, the distributed computing systems which process the analytics concurrently wi...

It is well known that cloud computing has many potential advantages over traditional distributed systems. Many enterprises can build their own private cloud with open source infrastructure as a service (IaaS) frameworks. Since enterprise applications and data are migrating to private cloud, the performance of cloud computing environments is of utmo...

Due to the loosely coupled property of cloud computing environments, no node has complete knowledge of the system. For this reason, detecting a Sybil attack in cloud computing environments is a non-trivial task. In such a dynamic system, the use of algorithms based on tree or ring structures for collecting the global state of the system has unfortu...

In this paper, we define the problem of sensor coverage in sparse mobile ad hoc networks. Previously, the nodes are assumed static or the number of nodes is large enough to cover the area for the coverage problem in wireless sensor networks. However, in sparse mobile ad hoc network environments, the semantics of the coverage problem differ in that...

Since advent of information revolution, there have been a lot of interest at big data analytics as well as big data. In the big data analytics, it is essential that not only extracting valuable information from the big data but also processing the data rapidly. Therefore, the distributed computing systems which process the analytics concurrently wi...

As information technology service matures to an even higher level and as sensor technology becomes embedded on person’s life, the needs to support and satisfy instant personal learning activity on own life without the limitation of time, space, and additional complement have become a vital point to everyday lives. Especially smartphone users are in...

We consider a cloud data center, in which the service provider supplies virtual machines (VMs) on hosts or physical machines (PMs) to its subscribers for computation in an on-demand fashion. For the cloud data center, we propose a task consolidation algorithm based on task classification (i.e., computation-intensive and data-intensive) and resource...

Information and communication technologies enable people to access to various documentations and information. Huge documents and information in the Internet or storage disks have made search time more important. Especially as the volume size and the number of documents on the Internet increase, string search times and costs increase have become big...

By improved internet technique, mobile users are rapidly increased and new types of mobile environment are come out. There are many mobility management protocols are proposed to provide seamless mobile network environment. In this paper, we focused on transportation environment. Transportation kind of bus, train, airplane or ship takes passengers u...

Virtualization is to provide virtually all types of technologies used on the physical PC. However, in a virtualization technique, services can be modified and adjusted to satisfy user requirements, the cost of hardware purchases and hardware constructions is not occurred. Beside, this virtualization supports multiple guest operating systems on a ho...

HPC is representative tools for performing large-scale scientific calculation both academia and industry. Tachyon is a high-performance parallel computing system which constructed based on SUN Blade X6275. It composed of 3,200 computing nodes and infra-facilities. Also, this machine works with various software stacks such as file system, archive ma...

Mobile grid is a branch of grid computing that incorporates mobile devices into the grid infrastructure. It poses new challenges because mobile devices are typically resource-constrained and exhibit unique characteristics such as instability in network connections. New scheduling strategies are imperative in mobile grid to efficiently utilize the d...

Cloud computing is a computing paradigm in which users can rent computing resources from service providers according to their requirements. A spot instance in cloud computing helps a user to obtain resources at a lower cost. However, a crucial weakness of spot instances is that the resources can be unreliable anytime due to the fluctuation of insta...

As computer systems have become more complex and dynamic, unstructured and decentralized techniques serve as basic building blocks in large-scale systems such as cloud computing systems. In particular, we consider a gossip-based algorithm, one of the unstructured overlay construction techniques. In this paper, we propose a membership management mec...

Cloud computing is a computing paradigm in which users can rent computing resources from service providers according to their requirements. Cloud computing based on the spot market helps a user to obtain resources at a lower cost. However, these resources may be unreliable. In this paper, we propose an estimation-based distributed task workflow sch...

The emerging Grid is extending the scope of resources to mobile devices and sensors that are connected through loosely connected networks. Nowadays, the number of mobile device users is increasing dramatically and the mobile devices provide various capabilities such as location awareness that are not normally incorporated in fixed Grid resources. N...

Recently, the cloud computing is a computing paradigm that constitutes an advanced computing environment that evolved from the distributed computing. And the cloud computing provides acquired computing resources in a pay-as-you-go manner. For example, Amazon EC2 offers the Infrastructure-as-a-Service (IaaS) instances in three different ways with di...

To detect deadlock in distributed systems, the initiator should construct an efficient explicit or implicit global wait-for graph. In this paper, we present an unstructured deadlock detection algorithm using a gossip protocol in cloud computing environments, where constituting nodes may join and leave at any time. Because of the inherit properties...

In cloud computing, users can rent computing resources from service providers according to their demand. Spot instances are unreliable resources provided by cloud computing services at low monetary cost. When users perform tasks on spot instances, there is an inevitable risk of failures that causes the delay of task execution time, resulting in a s...

Cloud computing is a computing paradigm in which users can rent computing resources from service providers according to their requirements. A spot instance in cloud computing helps a user to obtain resources at a lower cost, but it may be unreliable. In this paper, we propose a workflow scheduling scheme to consider task processing rate. This schem...

Traditional Byzantine consensus in distributed systems requires n ≥ 3f + 1, where n is the number of nodes. In this paper, we present a scalable and leaderless Byzantine consensus implementation based on gossip, requiring only n ≥ 2f + 1 nodes. Unlike conventional distributed systems, the network topology of cloud computing systems is often not ful...

Researches on utilizing mobile devices as resources in mobile cloud environments have gained attentions recently because of the enhanced computing power of mobile devices such as the advent of quad-core chips. However, mobile devices have several problems of the availability and the mobility. Especially, the availability and the mobility of mobile...

The cloud computing is a computing paradigm that users can rent computing resources from service providers as much as they require. A spot instance in cloud computing helps a user to utilize resources with less expensive cost, even if it is unreliable. In this paper, we propose the workflow scheduling scheme that reduces the task waiting time when...

In recent years, cloud computing has become a significant technology trend because of various advantages including cost savings, flexibility, high availability, and scalability using virtualization technology. However, one of the concerns for using cloud computing is security. In fact, there are multiple attack surfaces in virtualized environments....

Recently, with the rapid growth in the smart phone market and advancements in wireless communication environments, mobile devices are being considered as resources for the processing of fine-grained tasks. However, mobile devices have several problems such as unstable wireless connections, low communication bandwidth, and frequent location changes....

The performance of mobile devices including smart phones and laptops is steadily rising as prices plummet sharply. So, mobile devices are changing from being a mere interface for requesting services to becoming computing resources for providing and sharing services due to immeasurably improved performance. With the increasing number of mobile devic...

The purpose of this paper is to propose a training program for creative problem solving based on computer programming. The proposed program will encourage students to solve real‐life problems through a creative thinking spiral related to cognitive skills with computer programming. With the goal of enhancing digital fluency through this proposed tra...

This study evaluates the performance of the 64-core-based TILEPro64, and compares it with Core i7 and Atom by executing three benchmark programs: a synthetic bench, SPEC CINT2006 and SPLASH-2. TILEPro64 is not advertised for regular applications such as SPLASH-2. However, its internal many-core structure makes it worth investigating the performance...

The cloud computing is a computing paradigm that users can rent computing resources from service providers as much as they require. A spot instance in cloud computing helps a user to utilize resources with less expensive cost, even if it is unreliable. When a user performs tasks with unreliable spot instances, failures inevitably lead to the delay...

Determining termination in dynamic environments is hard due to node joining and leaving. In previous studies on termination detection, some structures, such as spanning tree or computational tree, are used. In this work, we present an unstructured termination detection algorithm, which uses a gossip based scheme to cope with scalability and fault-t...

To detection deadlock in distributed systems, the initiator should construct a global wait-for graph in an efficient way. In this paper, we present a deadlock detection algorithm using gossip for cloud computing environments where each node may leave and join at any time. Due to its inherit properties of a gossip protocol, we claim that our propose...

Termination detection is a fundamental problem in distributed systems. In previous research, some structures are used (e.g., spanning tree or computational tree) to detect termination. In this work, we present an unstructured termination detection algorithm, which uses a gossip based algorithm to cope with scalability and fault-tolerance issues. Th...

This article presents our cost-effective curriculum on embedded systems. Education on embedded systems requires coverage of both hardware and software aspects of the systems. Our curriculum uses one monolithic environment, virtual platform, to introduce all the layers of the system components (i.e., from hardware to operating systems to user applic...

Mutual exclusion is a salient feature in distributed computing systems whereby concurrent access of processors to a shared resource is granted in a mutually exclusive manner. The primary aim of this study is to investigate the use of a gossip protocol to a mutual exclusion algorithm to cope with scalability and fault-tolerance problems which are fu...

The researches on utilizing mobile devices as resources in mobile cloud environments have been gained attentions recently because of the enhanced computer power of mobile devices with the advent of dual cores chips. In this paper, propose a resource allocation technique which offers reliable resource allocation considering the availability of mobil...

Mobile grid supports a new infrastructure to integrate and utilize the exploding population of mobile resources. The mobile grid is not as reliable as the traditional wired grid, mainly due to the users' movement. In this paper, we propose a job scheduling method based on Genetic Algorithm in mobile grid. The scheduling scheme takes into account th...

The cloud computing is a computing paradigm that users can rent computing resources from service providers as much as they require. A spot instance in cloud computing helps a user to utilize resources with less expensive cost, even if it is unreliable. When a user performs tasks with unreliable spot instances, failures inevitably lead to the delay...

In multiple datacenters-based cloud environments, virtual machines migrates across nodes located in the same or different datacenter to provide users with efficient resource provisioning services. Especially, migration between nodes located in different datacenter usually works on a wide area network. However, it takes a longer time than a local ar...

Cloud computing is an Internet-based computing paradigm that provides services in a virtualized form composed of plenty of sharable resources. In cloud computing environments, gossip protocols are engaged as a method to rapidly disseminate the state information for innumerable resources. Although the gossip protocols provide a robust and scalable m...

In this paper, we present a fault tolerant and recovery system called FRASystem (Fault Tolerant & Recovery Agent System) using multi-agent in distributed computing systems. Previous rollback-recovery protocols were dependent on an inherent communication and an underlying operating system, which caused a decline of computing performance. We propose...

Mobile cloud computing is a combination of mobile computing and cloud computing, and provides cloud computing environment through various mobile devices. Recently, due to rapid expansion of smart phone market and wireless communication environment, mobile devices are considered as resource for large scale distributed processing. But mobile devices...

Mobile grid computing is a computing environment that incorporates mobile devices to an existing grid environment and supports users’ mobility. But this environment is not stable, so methodologies to cope with the reliability issue are needed. Fault tolerance approaches for task execution in grid computing can be categorized into replication and ch...

String searching algorithm is used to determine whether a word, a statement and a phrase exists in newspaper article, books, web pages or not. Especially as the volume of web pages and documentation increases, time and cost of searching a pattern increases. In this paper, we consider the characteristics of English alphabets combination in a pattern...

Mobile Grid is a branch of Grid where the infrastructure includes mobile devices. The mobile Grid exhibits different challenges such as resource-constraints and users’ movements, compared to the traditional Grid. Mobile agent is an attractive technology to overcome these challenges. In this paper, we present a new mobile Grid system based on the mo...

Mobile Grid is a branch of Grid computing where the infrastructure includes mobile devices. Because mobile devices are resource-constrained, mobile Grid should provide new scheduling strategies considering its environment. This paper presents a group-based fault tolerance scheduling algorithm. The algorithm classifies mobile devices into several gr...

When the workflow application is executed in Service-Oriented Grid (SOG), performance issues such as service scheduling should be considered, to achieve high and stable performance in execution. However, most of the prior works on workflow management neither study the performance issues nor provide evaluation methodologies on the performance of Gr...

Recently mobile devices become considered as grid resources as the technology of mobile devices and wireless communication network improves. But mobile devices have several problems such as instability of wireless communication, intermittent connection, limitation of power supply, and low communication bandwidth. These problems make it difficult to...

Recently, many studies have attempted to utilize mobile nodes as resources in mobile grids. Due to their underlying restrictions such as intermittent communication disconnections, limited battery capacity, and so on, mobile nodes are less reliable than wired nodes for job processing. Therefore, it is imperative to find an enhanced job scheduling me...

In this paper we discuss the design of result verification in desktop grid systems. In this design, correctness and performance are considered as important issues. To guarantee the correctness of work results, sabotage-tolerant mechanisms have been mainly used, such as voting-based schemes and trust-based schemes. However, these mechanisms result i...

A mobile grid is emerging as a new opportunity to integrate and utilize the exploding population of mobile resources. However, the mobile grid is not as stable as the traditional fixed grid, and the scheduling scheme plays a crucial role for the efficient job execution. In this paper, we take into account the characteristics of mobile devices such...

In this paper, we tried to enable a mobile device as a resource to access to the grid network. By improved Internet technique, the use of mobile devices is rapidly increased. And some researches in grid computing tried to combine grid computing with mobile devices. However, according to properties of mobile environments, mobile devices have many co...

An important issue in the PC grid computing environment that is characterized by volatility and heterogeneity is the minimization of execution time for all tasks. This paper proposes a scheduling mechanism to reduce such execution time by means of both checkpoint sharing and task duplication under a peer-to-peer (P2P) architecture. In the mechanism...

The emerging Grid is extending the scope of resources to mobile devices and sensors that are connected through unreliable networks. Nowadays the number of mobile device users is increasing dramatically and the mobile devices provide various capabilities such as location awareness that are not normally incorporated in fixed Grid resources. Neverthel...

A molecular docking is the process of reducing an unmanageable number of compounds to a limited number of compounds for the target of interest by means of computational simulation. And it is one of a large-scale scientific application that requires large computing power and data storage capability. Previous applications or software for molecular do...

Grid computing provides environment that can executes job efficiently by sharing resources in heterogeneous environment. Grid computing environment is evolving into wireless grid and mobile grid environments that consider user mobility and integrate mobile devices into wired grid. Recently, mobile devices are increasing by much in performance, and...

In the service oriented grid, a grid application can be composed of diverse grid services which may be already deployed on grid sites, and dependencies between these grid services can be described as the workflow graph. Though many grid scheduling methods have been developed, they have been studied based on static heterogeneous computing environmen...