• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.691-697
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• 2017

Volcanic ash has been predicted to be the main source of damage caused by a potential volcanic disaster around Mount Baekdu and the regions of the Korean peninsula. Computer simulations to predict the diffusion of volcanic ash should be performed according to prevalent meteorological situations within a predetermined time. Therefore, a workflow using pipelining is proposed to parallelize the software used for this computation. Due to the nature of volcanic calamities, the simulations need to be carried out for various plausible conditions given that the parameters cannot be precisely determined during the simulations, even at the time of a volcanic eruption. Among the given conditions, computations need to be first performed for the condition with the highest probability so that a response to the volcanic disaster can be provided using these results. Further action can then be performed later based on subsequent results. The computations need to be performed using a volcanic disaster damage prediction system on a computing server with limited computing performance. Hence, an optimal distribution of the computing resources is required. We propose a method through which specific data can be provided first to the proposed pipeline-based workflow.

• Korean Journal of Construction Engineering and Management
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• v.8 no.1 s.35
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• pp.78-86
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• 2007

Top priority to manage construction projects is given to the planning and scheduling in order to keep the project duration, which is one of the most important factors in construction management. However, recently most of public construction projects especially for civil projects are delays and preventive research, many efforts were made concerning construction delays and preventive management methods. But analysis of delay causation, which is a main key to solve the problems is not done, yet. Therefore, in this research causation delays are analyzed by characteristics of construction projects, which are type of projects, type of contracts, project participants, and general condition. As a result of the analysis, delay causation are proved to be different by characteristics of the projects. The research results will be used for prevention of time extension and dispute resolution.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.1
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• pp.37-48
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• 2011

Sensor networks monitor the environment, collect sensed data, and relay the data back to a collection point. Although sensor nodes have very limited hardware resources, they require an operating system that can provide efficient resource management and various application environments. In addition, the wireless sensor networks require the code update previously deployed to patch bugs in program and to improve performance of kernel service routines and application programs. This paper presents EPRCU (Easy to Perform Remote Code Update), a new operating system for wireless sensor nodes, which has enhanced functionalities to perform remote code update. To achieve an efficient code update, the EPRCU provides dynamic memory allocation and program memory management. It supports the event-driven kernel, which uses priority-based scheduling with the application of aging techniques. Therefore, the proposed operating system is not only easy to perform wireless communication with the remote code update but also suitable for various sensor network applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2055-2062
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• 2013

Digital evidence which is the new form of evidence to crime makes little difference in value and function with existing evidences. As time goes on, digital evidence will be the important part of the collection and the admissibility of evidence. Usually a digital forensic investigator has to spend a lot of time in order to find clues related to the investigation among the huge amount of data extracted from one or more potential containers of evidence such as computer systems, storage media and devices. Therefore, these evidences need to be ranked and prioritized based on the importance of potential relevant evidence to decrease the investigate time. In this paper we propose a methodology which prioritizes order in which evidences are to be examined in order to help in selecting the right evidence for investigation. The proposed scheme is based on Fuzzy Multi-Criteria Decision Making, in which uncertain parameters such as evidence investigation duration, value of evidence and relation between evidence, and relation between the case and time are used in the decision process using the aggregation function in fuzzy set theory.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.810-815
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• 2009

In recent years, embedded systems such as cellular phones, Portable Multimedia Player, intelligent appliance, automobile engine control are reshaping the way people live, work, and play. Thereby, applications for embedded systems become increasingly sophisticated and complicated, such embedded computing platforms must use real-time operating systems (RTOSs) with time determinism. These RTOSs must not only provide predictable services but must also be efficient and small in size and it's kernel services should also be deterministic by specifying how long each service call will take to execute. Having this information allows the application developers to better plan their real-time application software so as not to miss the deadline of each task. In this paper, we present the complete generalized algorithm using multi-dimensional methodology to determine the highest priority in the ready list with 2r levels of priorities for an arbitrary integer number of r.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.979-985
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• 2012

The design of an efficient scheduler is a key design factor in IEEE 802.16m systems, in order to support services with various QoS smoothly. Although conventional studies of schedules have been suggested, those had problems that are not able to satisfy the delay condition and make the through-put declined, because they only focused on a specific action scenario rather than reflecting practical action scenarios which have real-time and non-real-time traffics variously. In this paper, an efficient uplink scheduling algorithm is proposed for IEEE 802.16m system by introducing the concepts of Virtual Time(VT) and Virtual Finish Time(VFT) based priority determination, and separate buffers for each QoS class in the mobile terminal. Simulation results showed that the proposed scheme had satisfied the delay requirement of real-time services even with improved throughput performance compared to conventional methods.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.71-79
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• 2005

As construction projects have been extremely enormous, complex and special, risk factors have been increased consistently. Therefore, it is very important to identify and cope with the uncertain risk factors in such building constructions for successful project accomplishment. The purpose of this research is to approach practical affairs directly and show detail alternatives of risk factors by extracting the risk factors throughout construction process of curtain wall that is largely influenced on cost, quality, schedule ,safety and following activity. Also, extracting these risk factors make it possible to analyze quantitative risk and decide the priority raking of risk factors. Especially, this research is aimed to provide efficient management of scheduling risk that can make the risk minimize to practical workers who have different degree of knowledge and experience to the construction cite when the risk brings out suddenly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.9
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• pp.1551-1557
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• 2006

Since subscribers, who pay the same communication fees, have a strong desire to take similar services with the other users, it is an important issue to provide fairness among those subscribers wherever they are located. Therefore, in this paper we propose a QoS packet scheduler that can provide fairness among wireless LAN terminals and evaluate its performance using computer simulation. The key idea of this scheduler is to reduce the CW value of the wireless LAN terminal that has failed in sending its packets due to channel transmission error in order to offer the wireless MM terminal a higher transmission priority which is the idea of service compensation. We evaluate its performance using NS-2 network simulator, compare its numerical results to those of IEEE 802.11e without this scheme, and conclude that this scheme can reduce throughput difference between similar wireless LAN terminals.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.140-148
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• 2011

Multimedia streaming service is susceptible to loss and delay of data as it requires high bandwidth and real time processing. Therefore QoS cannot be guaranteed due to data loss caused by heavy network traffic. To deal with these problems, a study on algorithm that can provide high quality multimedia service by considering both network congestion and characteristics of multimedia data is required. In this paper, we propose APQM algorithm which probabilistically removes packet by the congestion level of the queue in wireless station. The comparison with other existing scheduling algorithms shows tht congestion in the network is reduced and multimedia service quality of the proposed algorithm is improved.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.543-550
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• 2002

This paper proposes the dynamic slot allocation method for real-time VBR (rt-VBR) services in wireless ATM networks. The proposed method is characterized by a contention-based mechanism of the reservation request, a contention-free polling scheme for transferring the dynamic parameters. The base station scheduler allocates a dynamic parameter minislot to the wireless terminal for transferring the residual lifetime and the number of requesting slots as the dynamic parameters. The scheduling algorithm uses a priority scheme based on the maximum cell transfer delay parameter. Based on the received dynamic parameters, the scheduler allocates the uplink slots to the wireless terminal with the most stringent delay requirement. The simulation results show that the proposed method guarantee the delay constraint of rt-VBR services along with its cell loss rate significantly reduced.