• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.674-690
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• 2021

This study proposes a hybrid marine power system combining dual-fuel generators, a fuel cell, and Vanadium Redox Flow Batteries (VRFB). Rigorous verification and validation of the dynamic modelling and integration of the system are conducted. A case study for the application of the hybrid propulsion system to a passenger ship is conducted to examine its time-variant behaviour. A comprehensive model of the reversible and irreversible capacity degradation of the VRFB stack unit is proposed and validated. The capacity retention of the VRFB stack is simulated by being integrated within the hybrid propulsion system. Reversible degradation of the VRFB stack is precisely predicted and rehabilitated based on the predefined operational schedule, while the irreversible portion is retained until the affected components are replaced. Consequently, the advantages of the VRFB system as an on-board ESS are demonstrated through the application of a hybrid propulsion system for liner shipping with fixed routes.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.1181-1186
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• 2005

In many construction projects, progress and efficiency are hampered by poor communication of discipline-specific models. For example, architects use 2D or 3D CAD models and builders use CPM diagrams, Gantt charts, and spreadsheets to show their view of the project. Nowadays, advanced computer visualization tools, 4D CAD or VR, can show these disparate models to understand cross-disciplinary impacts of design and construction decisions. In Korea, several leading companies have tried to apply these tools to their pilot projects from the design phase to the maintenance phase. These companies have expected that more project stakeholders could understand a construction schedule more quickly and completely with 4D visualization than with the traditional construction management tools. However, modeling of the 4D CAD or VR can be quite time-consuming and expensive to generate manually and has therefore limited the spread and use of these models. In order to adopt widely those models in construction industry, the areas that those tools could support to take large benefits in diverse functional areas of construction management need to be analyzed. In this study, researchers analyze the usefulness and limitations of the 4D models and VR in the construction industry, develop the strategy of application priority, and improve the 4D modeling method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.5 s.335
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• pp.63-72
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• 2005

This paper describes a new approach for the operating system level power management to reduce the energy consumed in the IO devices in a robot platform, which provides various functions such as navigation, multimedia application, and wireless communication. The policy proposed in the paper, which was named the Energy-Aware Job Schedule (EAJS), rearranges the jobs scattered so that the idle periods of the devices are clustered into a time period and the devices are shut down during their idle period. The EAJS selects a schedule that consumes the minimum energyamong the schedules that satisfy the buffer and time constraints. Note that the burst job execution needs a larger memory buffer and causes a longer time delay from generating the job request until to finishing it. A prototype of the EAJS is implemented on the Linux kernel that manages the robot system. The experiment results show that a maximum $44\%$ power saving on a DSP and a wireless LAN card can be obtained with the EAJS.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.19-28
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• 2000

The scheduling problem in parallel processing systems has been a challenging research issue for decades. The problem is defined as finding an optimal schedule which minimizes the parallel execution time of an application on a target multiprocessor system. Duplication Based Scheduling (DBS) is a relatively new approach for solving the problem. The DBS algorithms are capable of reducing communication overhead by duplicating remote parent tasks on local processors. Most of DBS algorithms assume an availability of the unlimited number of processors in the system. Since the assumption may net hold in practice, the paper proposes a new scalable DBS algorithm for a target system with limited number of processors. It Is shown that the proposed algorithm with N available processors generates the same schedule as that obtained by the algorithm with unlimited number of processors, where N is the number of input tasks. Also, the performance evaluation reveals that the proposed algorithm shows a graceful performance degradation as the number of available processors in the system is decreased.

• Journal of Broadcast Engineering
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• v.14 no.5
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• pp.625-637
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• 2009

With advent of TV environment and increasing of variety of program contents, users are able to experience more various and complex environment for watching TV contents. According to the change of content watching environment, users have to make more efforts to choose his/her interested TV program contents or TV channels than before. Also, the users usually watch the TV program contents with their own regular way. So, in this paper, we suggests personalized TV program schedule recommendation system based on the analyzing users' TV watching history data. And we extract the users' watched program patterns using the sequential pattern mining method. Also, we proposed a new sequential pattern mining which is suitable for TV watching environment and verify our proposed method have better performance than existing sequential pattern mining method in our application area. In the future, we will consider a VoD characteristic for extending to IPTV program schedule recommendation system.

• Korean Journal of Construction Engineering and Management
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• v.3 no.4 s.12
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• pp.114-122
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• 2002

Earned Value Management System(EVMS) is a management technique that is emerging as a valuable tool in the management of all projects, including and in particular construction projects. It is based on C/SCSC that has been released by the U.S. Department of Defense (DOD) in 1967. In a project that employs the earned value management concept, the project's measurable performance plans will be formed with the creation of CAPs. The formation of CAPs is a planning step necessary to form an earned value baseline. In this paper, a method is proposed to form CAPs using Material Requirement Planning(MRP) that is also known as a useful planning tool in the manufacturing industry. An application to a real project has been carried through workpackaging model.

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.26-35
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• 2009

Work breakdown structure (WBS) can be used as an information center in earned value management system (EVMS) for the construction project. Because EVMS results, such as schedule variance and cost variance, are analyzed for the selected WBS code, the role of WBS code is important in EVMS. This study suggests a methodology for organizing WBS map with a quadrant. It can represent the project organization collectively by work level in a coordinate system. And the study developed an EVMS tool based on the WBS map and this tool can visualize various attribute indexes of EVMS by color symbols. Those methodologies can be used for improving practical application of EVMS.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.135-145
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• 2010

Efficient Directed Acyclic Graph(DAG) scheduling is critical for achieving high performance in Distributed Heterogeneous computing System(DHCS). In this paper, we present a new high-performance scheduling algorithm, called the LCFT(Levelized Critical First Task) algorithm, for DHCS. The LCFT algorithm is a list-based scheduling that uses a new attribute to efficiently select tasks for scheduling in DHCS. The complexity of LCFT is $O(\upsilon+e)(p+log\;\upsilon)$. The performance of the algorithm has been observed by its application to some practical DAGs, and by comparing it with other existing scheduling algorithms such as PETS, HPS, HCPT and GCA in terms of the schedule length and SpeedUp. The comparison studies show that LCFT significantly outperforms PETS, HPS, HCPT and GCA in schedule length, SpeedUp.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.501-506
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• 2019

This paper presents a prescriptive alternative for establishing a FRMS suitable for us based on scientific data ahead of the introduction and implementation of the FRMS for air traffic controllers in order to meet the International Civil Aviation Organization (ICAO) international standards. I would like to present. Therefore, we confirmed the operation of each air traffic control agency against the current domestic operating standards, and compared and reviewed the operation methods and standards of air traffic control agencies in each country. The controller in Korea defines 10 hours of working hours per day, 8 hours of minimum breaks, and 40 hours per week. Currently, in the case of air traffic control agencies, the daytime and the appropriate working hours are used in the daytime, but in the nighttime, the average time exceeds 5.9 hours. In the case of 40 hours a week, they work an average of 15.7 hours overtime. By adjusting the nighttime work time, this work can be solved by diversifying the form of the worker's input method according to the personal schedule rather than the two-day (day / night) method, as well as the appropriate nighttime time distribution by supplementing the personnel.

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.35-44
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• 2000

The major objective of construction process control(CPC) is to provide construction managers with operational information that will help reduce project duration and save project cost. However, the CPC in Korea is being applied to construction projects with some basic problems such as the inconvenience of CPC S/Ws and the process control unconcerned with construction information classification system and computer system to integrate cost and schedule. This study analyzes the present condition of CPC including the basic problems, and then suggests the reform measures in technical and operational viewpoints to reduce construction risk. The focus of study is on the technical improvement for the application of construction information management system applicable to both cost estimating and schedule management.