• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.646-651
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• 2017

The purpose of this study is to design a proper evaluation method for analysing the safety management efficiency of coastal ship companies, and to verify these evaluation standards by applying them to a representative company. For this purpose, 5 evaluation items and 14 specific sub-evaluation elements have been determined after collecting practical opinions from a group of expert, which consisted of safety managers in passenger ship companies, public servants as a ship inspector, passenger ship operations managers, etc. Next, the safety management levels of 44 coastal passenger ship companies were evaluated using these standards. Finally, the validity of the proposed evaluation method was verified through comparison analysis between the evaluation results and the ratio of major marine accidents. It was determined that companies with low evaluation levels were saw more major marine accidents than other coastal passenger ship companies, spurring greater interest in safety management. In conclusion, evaluation standards allow coastal passenger ship companies to voluntarily assess their safety management level were established. The result can also be applied to analyse the operation efficiency of coastal passenger ship companies.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.369-377
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• 2008

Interest in high productivity and streamlined operation is growing amid a heated competition between ports and mega size vessel oriented operation. It becomes clear that terminals that operate YT(Yard Tractor) for transportation in container yard have less efficiency in operation and cost comparing terminals functioning AGV(Automated Guided Vehicle) system. To offset disadvantages arising out of YT operations, continual efforts (e,g YT pooling operation) were taken place for the last decade, but the result has not been fruitful; YT pooling operation still has a problem in that it cannot read individual YT's actual location. This study suggests 'YT dynamic operation model'- a practical application of RTLS(Real Time Location System) technology which will solve YT pooling operation problems.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.85-91
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• 2014

Cloud storage system uses a distributed file system for storing and managing data. Traditional distributed file system makes a triplication of data in order to restore data loss in disk failure. However, enforcing data replication method increases storage utilization and causes extra I/O operations during replication process. In this paper, we propose a data replication method using erasure codes in cloud storage system to improve storage space efficiency and I/O performance. In particular, according to data access frequency, the proposed method can reduce the number of data replications but using erasure codes can keep the same data recovery performance. Experimental results show that proposed method improves performance in storage efficiency 40%, read throughput 11%, write throughput 10% better than HDFS does.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.157-160
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• 2002

This study was carried out to the harvesting efficiency of equipment used fer harvesting of rhizomes of Saururus chinensis Bail. Labor-saving efficiency showed 60-67% enhancement by using tillage operations with power tiller, digger attached to power tiller, and digger attached to tractor compared with manual harvest. Loss percentage of rhizomes by harvesting equipments was 2.2-8.8% lower than by manual harvest. Fresh rhizome yield and income index were increased 3-10% and 13-27% respectively by harvesting equipments, showing the highest yield and index in digger attached to tractor, Thus, digger attached to tractor showed the most effective harvest equipment for Saururus chinensis rhizome.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.9
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• pp.305-316
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• 2022

With the flood of digital data owing to the Internet of Things and big data, cloud service providers that process and store vast amount of data from multiple users can apply duplicate data elimination technique for efficient data management. The user experience can be improved as the notion of edge computing paradigm is introduced as an extension of the cloud computing to improve problems such as network congestion to a central cloud server and reduced computational efficiency. However, the addition of a new edge device that is not entirely reliable in the edge computing may cause increase in the computational complexity for additional cryptographic operations to preserve data privacy in duplicate identification and elimination process. In this paper, we propose an efficiency-improved duplicate data elimination protocol while preserving data privacy with an optimized user-edge-cloud communication framework by utilizing a trusted execution environment. Direct sharing of secret information between the user and the central cloud server can minimize the computational complexity in edge devices and enables the use of efficient encryption algorithms at the side of cloud service providers. Users also improve the user experience by offloading data to edge devices, enabling duplicate elimination and independent activity. Through experiments, efficiency of the proposed scheme has been analyzed such as up to 78x improvements in computation during data outsourcing process compared to the previous study which does not exploit trusted execution environment in edge computing architecture.

• The Journal of Korean Association of Computer Education
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• v.12 no.4
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• pp.47-55
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• 2009

There are many researches considering mobile devices as resources in mobile grids. However, the mobile device has some limitations: wireless connection and battery capacity. So, the grid operations using mobile devices have lower reliability and efficiency than those in fixed grid environments. In this paper, we propose a job migration scheme using mobile devices to overcome these limitations. The proposed job migration scheme predicts failure condition during execution and takes checkpoints. Then, if the failure occurs on mobile device during execution, the executing job can be migrated to other mobile device by checkpoint information. To perform the proposed migration scheme, we establish a mobile device manager on a proxy server and a status manager on a mobile device. Connection, wireless signal strength and battery capacity of mobile devices are identified through two managers. The simulation results show improvement of efficiency and reliability during execution.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.82-86
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• 2010

In this paper, a power amplifier module for WCDMA base-station applications is designed and implemented using GaN field-effect transistors (FETs), which uses an envelope tracking bias system. The designed module consists of an high gain MMIC amplifier, a driver amplifier, a power amplifier, and bias circuits for envelope tracking applications. Especially, a FET bias sequencing circuit and two isolators are integrated for stable RF operations. All circuits are assembled within a single housing, so its dimension is just $17.8{\times}9.8{\times}2.0\;cm3$. Measured results show that the developed power amplifier module has good envelope tracking capability: the power-added efficiency of 35% at the output power range from 30dBm to 40dBm over a wide range of drain bias.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.1028-1037
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• 2011

Recently, Selim et al proposed public key cryptography based privacy preserving multi-context RFID authentication protocol. However Selim et al's proposed protocol not only doesn't fit into passive tag based RFID system because it uses public key based encryption algorithm to perform authentication between reader and tag, but also is insecure to an impersonation attack because it doesn't provide mutual authentication. In order to eliminate the above described efficiency problem and security vulnerabilities, this paper proposes a new multi-context RFID mutual authentication protocol that can prevent privacy invasion and tag impersonation attack through providing mutual authentication between single passive tag which is located different application space and readers which provide multi-context purposes and can secure against relay attack and denial-of-service attack. As a result, the proposed protocol performs secure mutual authentication based on the collected space and time information from the RFID reader and provides strong security and high computation efficiency because if performs secure one-way hash function and symmetric encryption operations suitable to the environments of passive RFID tags.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.472-479
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• 2024

Half of the world's total population lives in cities, continuous urbanization is progressing, and the urban population is expected to exceed two-thirds of the total population by 2050. To resolve this phenomenon, the Korean government is focusing on building a new urban air mobility (UAM) industrial ecosystem. Airlines are also part of the UAM industry ecosystem and are preparing to improve efficiency in safe operations, passenger safety, aircraft operation efficiency, and punctuality. This study performs demand forecasting using time series data on the number of daily passengers on Korean Air's Gimpo to Jeju route from 2019 to 2023. For this purpose, statistical and machine learning models such as SARIMA, Prophet, CatBoost, and Random Forest are applied. Methods for effectively capturing passenger demand patterns were evaluated through various models, and the machine learning-based Random Forest model showed the best prediction results. The research results will present an optimal model for accurate demand forecasting in the aviation industry and provide basic information needed for operational planning and resource allocation.

• Informatization Policy
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• v.31 no.3
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• pp.88-105
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• 2024

Many companies are adopting Information System (IS) operation outsourcing to focus on their core competencies and enhance operational efficiency. However, most of them employ a headcount-based pricing model, which often leads to exhaustive negotiations over contract costs without objective criteria or systematic frameworks. This headcount-based outsourcing contract environment results in low motivation/incentives for both client companies and IT service providers to improve productivity, efficiency, and quality, which poses challenges in securing a competitive advantage. This study introduces the development process of an IS operation outsourcing pricing model, which was collaboratively developed and agreed upon for implementation in actual contracts by an IT service company of a conglomerate. Also, the study underscores the activities undertaken to secure IT service competitiveness based on this model so as to deliver a practical guide for companies seeking to transition their outsourcing contract methods.