• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.439-446
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• 2001

The main stream of parallel programming today is using synchronous algorithms, where processor synchronization for correct computation and workload balance are essential. Overall performance of the whole system is dependent upon the performance of the slowest processor, if workload is not well-balanced or heterogeneous clusters are used. Asynchronous iteration is a way to mitigate such problems, but most of the works done so far are for shared memory systems. In this paper, we suggest and implement a parallel large sparse linear system solver that improves performance on distributed memory systems like clusters by reducing processor idle times as much as possible by asynchronous iterations.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.1-9
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• 2010

Predictive information on the freeway incident impacts can be a critical criterion in selecting travel options for users and in operating transportation system for operators. Provided properly, users can select time-effective route and operators can effectively run the system efficiently. In this study, a model is proposed to predict freeway incident impacts. The predictive model for incident impacts is based on short-term prediction. The proposed models are examined using MARE. The analysis results suggest that the models are accurate enough to be deployed in a real-world. The development of microscopic models to predict incident effects is expected to help minimize traffic delay and mitigate related social costs.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.570-587
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• 1993

Recently a number of severe fuel degradation events, seemingly due to internal secondary hydriding, have been reported. This paper reviews internal hydriding of defected zircaloy cladding. First, the history of zircaloy cladding development and the environment of the zircaloys in service in the nuclear reactor are introduced. Fundamental aspects of zircaloy hydriding, such as hydrogen permeability in zirconium oxide, terminal solubility and precipitation in zirconium and its alloys, and the deleterious effect of hydrides are reviewed. The mechanism of massive internal hydriding in defected zircaloy fuel rods is qualitatively described based on the observed phenomena. Significant factors affecting the hydriding process are discussed. A quantitative model for the massive hydriding as a part of an effort to mitigate fuel degradation is briefly mentioned and necessary information and recommended future work for improvement of the model are outlined.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.140-145
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• 2014

Exploitation of renewable energies is on the increase to mitigate the reliance on fossil fuels and other natural gases with rocketing prices currently due to the depletion of their reserves not to mention their diverse consequences on the environment. Divergently, there are lots of industries "throwing" heat at higher temperatures as by products into the environment. This waste heat can be recovered through organic Rankine systems and converted to electrical energy with a waste heat recovery organic Rankine cycle system (WHR-ORC). This study uses the annual average condenser effluent from Namhae power plant as heat source and surface seawater as cooling source to analyze a waste heat recovery organic Rankine cycle using the Aspen HYSYS simulation software package. Hydrocarbon mixtures are employed as working fluid and varied in a ratio of 9:1. Results indicate that Pentane/Isobutane (90/10) mixture is the favorable working fluid for optimizing the waste heat recovery organic Rankine cycle at the set simulation conditions.

• Asia pacific journal of information systems
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• v.24 no.4
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• pp.473-491
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• 2014

There is a growing interest for 'Cloud computing' to cut costs, and help the users focus on their core business instead of being impeded by IT obstacles. As it became IT version 3.0 which represents the era of cloud services and the dominance of a new kind of IT service provider, cloud service providers (CSPs)' role is more critical as a trusted IT advisor to include cloud migration and integration expertise. However, previous literatures related to cloud computing service have mainly analyzed from customers, although it is hard for customers to totally understand the complex and diverse cloud ecosystem. Therefore, it is an urgent task to mitigate the inhibitory factors in providing the cloud services for activating cloud industry. This study, an exploratory research based on interviews, has derived factors of promoting and hindering the activation of cloud computing from the provider's perspective, and has analyzed a sequence of cause and effect for each factor. For this, the casual loop diagram was developed to deduce key issues, and propose an alternative. The results of this study are expected to help activate 'Cloud computing' in Korea by minimizing the potential negative effects of activating 'Cloud computing' industry.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3046-3060
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• 2012

Low power listening (LPL) MAC protocols based on duty-cycling mechanism have been studied extensively to achieve ultra low energy consumption in wireless sensor networks (WSNs). Especially, recent ACK-based LPL schemes such as X-MAC employ strobe preambles and an early ACK, and show fair performances in communications and energy efficiencies. However, the state-of-the-art ACK-based LPL scheme still suffers from collision problems due to the protocol incompleteness. These collision effects are not trivial and make WSNs unstable, aggravate energy consumptions. In this paper, we propose two novel schemes; (i) ${\tau}$-duration CCA to mitigate the collision problem in ACK-based LPL MAC protocols. (ii) Short Preamble Counter (SPC) to conserve more energy by reducing unnecessary overhearing. We demonstrate the performance improvement of our scheme via a mathematical analysis and real-time experiments. Both analysis and experimental results confirm that our proposed scheme saves energy by up to 36% compared to the naive ACK-based LPL MAC protocol thanks to ${\tau}$-duration CCA and SPC.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.163-172
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• 2015

This study examined the potential effects of urban growth on streamflow in the Gyungan River watershed, Korea, using urban containment scenarios. First, two scenarios (conservation and development) were established, and SLEUTH model was adapted to predict urban growth into the year 2060 with 20 years interval under two scenarios in the study area. Urban growth was larger under scenario 2, focusing on development, than under scenario 1, focusing on conservation. Most urban growth was predicted to involve the conversion of farmland, forest, and grasslands to urban areas. Streamflow in future periods under these scenarios was simulated by the Soil and Water Assessment Tool (SWAT) model. Each scenario showed distinct seasonal variations in streamflow. Although urban growth had a small effect on streamflow, urban growth may heighten the problems of increased seasonal variability in streamflow caused by other factor, such as climate change. This results obtained in this study provide further insight into the availability of future water resource and can aid in urban containment planning to mitigate the negative effects of urban growth in the study area.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.51-58
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• 2003

Generally, multi-path is viewed as an undesirable feature of wireless communications. Therefore, diversity reception and adaptive array schemes are proposed to mitigate its effects. Recently, to increase the spectrum efficiency and the link reliability, multiple-input multiple-output (MIMO) scheme is devised to exploit multi-path in a scattering wireless channel. In this paper, we have evaluated the channel capacity of MIMO Multi-Carrier CDMA system in path correlation fading channel. And, the channel capacity of MIMO system is compared with single-input single-output (SISO) system. From the results, the MIMO multi-carrier CDMA system with path correlation yields better performance with respect to channel capacity than a SISO system.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.2
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• pp.45-54
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• 2019

This study examines whether auditors restrain the analysts' opportunistic behavior as reviewing the companies' interim reports. Analysts' forecasts show a walkdown pattern in which their optimism has decreased as the earnings announcement date has approached. At the beginning of the year, there is a lack of high-quality benchmark information that enables information users to judge the accuracy of analyst's earnings forecasts. Thus, early in the year, analysts are highly inspired to disseminate optimistic forecasts in order to gain manager's favor. In this study, we examine adequate benchmarks prevent analysts from disclosing optimistically biased forecasts. We conjecture that auditors' efforts might mitigate analysts' walkdown pattern. To test this hypothesis, we use data from Korea, where it is mandatory to disclose auditor's review hours. We find that the analyst forecast's walkdown decreases with the ratio as well as the number of audit hours. It implies that an auditor's effort in reviewing interim financial information has a monitoring function that reduces analysts' opportunistic optimism at the beginning of the year. We conjecture that the tendency will be more pronounced when BIG4 auditors review the interim reports. Consistent with the prediction, BIG4 auditors' interim review effort is more effective in suppressing the analysts' walkdown.

• Resources Recycling
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• v.29 no.1
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• pp.62-69
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• 2020

Manufacturing processes in industrial complexes produce NOx, SOx, VOCs, which cause particulate matter (PM). Therefore, this study analyzed the characteristics of each industrial complex by using scattered public data, matched the existing particulate matter(PM) reduction technology, and proposed an optimized reduction plan. The application of matching technologies and facilities by industrial complexes based on data is able to mitigate NOx, SOx, and VOCs which cause particulate matter in the process in advance. This way can be an effective alternative in order to reduce PM in the manufacturing processes as well as industrial complexes.