• Journal of Korean Institute of Industrial Engineers
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• v.39 no.6
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• pp.461-472
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• 2013

In this paper, we deal with a simulation-based reliability and maintainability design problem of a warship and want to determine the optimal values of MTBF and MTTR of all units and ALDT of the warship. The system availability and life cycle cost are used as optimization criteria and estimated by simulation. A hybrid genetic algorithm with a heuristic method is proposed to find near-optimal solutions and numerical examples are also studied to investigate the effect of model parameters to the optimal solutions and compare with a general genetic algorithm.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.900-908
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• 2010

Recently, OOM(Object-Oriented Method) access method which begins to apply to software development is emphasizing development cost and time reduction through independent software reuse. But because of planning to the exclusion of the lack of knowledge and expansion or performance for development technology many problems are coming out. Therefore, this thesis suggests Effective Object-Oriented Modeling methods considering the plan for higher productivity enhancement of software in the software development life cycle. Effective Object-Oriented Modeling method includes, methods, Use Case modeling methods, Analysis Modeling methods, Design Modeling methods and others.

• Journal of Information Technology Services
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• v.7 no.4
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• pp.179-198
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• 2008

It is widely known that usability is a critical quality attribute of IT systems. Many studies have developed various methods for finding out usability problems. Usability professionals have emphasized that usability should be integrated into the development life cycle in order to maximize the usability of systems with minimal cost. To achieve this, it is essential to classify usability problems systematically and connect them into the activities of designing user interfaces and tasks. However, there is a lack of framework or method for these two problems and thus remains a challengeable research issue. As a beginning study, this paper proposes a conceptual framework for addressing the two issues. We firstly summarize usability-related studies so far, including usability factors and evaluation methods. Secondly, we review seven approaches to identifying and classifying usability problems. Based on this review and opinions of usability engineers in real industry as well as the review results, this paper proposes a framework comprising three viewpoints, from which more sound classification scheme of usability problems can be inductively developed.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.21-32
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• 2010

Software maintenance is one of the major activities of the software development life cycle. Due to the time and cost constraint it is not possible to perform exhaustive regression testing. Thus, there is a need for a technique that selects and prioritizes the effective and important test cases so that the testing effort is reduced. In an analogous study we have proposed a new variable based algorithm that works on variables using the hybrid technique. However, in the real world the programs consist of multiple modules. Hence, in this work we propose a regression testing algorithm that works on interprocedural programs. In order to validate and analyze this technique we have used various programs. The result shows that the performance and accuracy of this technique is very high.

• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.108-113
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• 2003

The safety of staff, customers and of general Public in general viewed as one of the most important requirements in the urban transit. The maintenance computerization system for car of urban transit is a part of standardization and development of urban transit system, and We have been performed the establishment of maintenance computerization system from 2001 to 2005. The RAMS(reliability, availability, maintainability and safety) estimation for maintenance computerization system are utilized in a variety of computerization system for user's convenience and safety in maintenance. Ever since its inception though, the urban transit has searched for ways to improve reliability, availability, maintainability and safety of the railway subsystem. Provision of a reliable maintenance system include RAMS of the vehicles plays a very important role in achieving a safe system.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.100-106
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• 2008

Road on the urban underground railway has been repaired for several years right after completion caused by the settlement of backfill and the damage of utility lines, which demands the practical application of life-cycle cost on design of backfill. This study perform the VE and LCC Analysis to select a optimal method of backfill and present the models and factors of VE process in the consideration of specialists' opinion and judgement on the category of critical maintenance items.

• Nuclear Engineering and Technology
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• v.34 no.2
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• pp.176-185
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• 2002

A 4-bundle shift refuelling method of CANDU6 F/H (Fuel Handling) System is analyzed to assess the operational flexibility and capacity of F/H system. The current 8-bundle shift refuelling scheme requires to refuel eight fuel bundles from a single fuel channel, and to refuel 14 fuel channels in a week on average assuming that the reactor is in a steady state. The analysis showed that the 4-bundle shift refuelling method increases F/M (Fuelling Machine) duty cycle and operator load. However, the fuellin’g method change from the 8- to 4-bundle shift refuelling ill not require additional team of operators. A marginal increase in the maintenance cost may be resulted in by the change of fuelling method and the increase of fatigue usage factors requires some components to be replaced during the FM lifetime.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.2
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• pp.53-61
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• 2019

In this paper, we propose 'a self - conformance system of convergence security provider' to provide basic data for security and reliability of convergence industrial technology, system and service. It is difficult to evaluate convergence security systems, limited to information and communication service providers, unable to check convergence security items, burden of submission documents, difficulty in measuring convergence security service level and we will summarize product and service-based requirements that can be integrated and systematically measure the level of convergence security and define renewed life cycle-based convergence security information and content security and assurance requirements. On the basis of this, each convergence security company declares conformity with the standard itself without the certification of the certification body, and introduces the provider conformity certification system which can manufacture and sell. This will enable the company to strengthen its competitiveness through timely launch and implementation of products and services and cost reduction.

• Wind and Structures
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• v.32 no.4
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• pp.321-340
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• 2021

In 2019, 5.6% of the total energy produced worldwide came from wind. Offshore wind generation is still a small portion of the total wind generation, yet its growth is exponential. Higher availability of sites, larger producibility and potentially lower environmental impacts make offshore wind generation attractive. On the other hand, as the water depth increases, fixed foundations are no more viable, and the new frontier is that of floating foundations. This paper brings an overview of why and how offshore wind energy should move deep water; it contains material from the Keynote Lecture given by the first author at the ACEM20/Structures20 Conference, held in Seoul in August 2020. The paper is organized into four sections: the first giving general concepts about wind generation especially offshore, the second and the third considering economic and technical aspects, respectively, of offshore deep-water wind generation, in the fourth, some challenges of floating offshore wind generation are presented and some conclusions are drawn.

• Journal of the Korean Chemical Society
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• v.67 no.3
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• pp.165-174
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• 2023

The development of all-solid-state batteries (ASSBs) has been gaining attention in recent years due to their potential to offer higher energy densities, improved safety, and longer cycle life compared to conventional lithium-ion batteries. However, several challenges must be addressed to achieve the practical application of ASSBs, such as the development of high-performance solid-state electrolytes, stable electrode-electrolyte interfaces, and cost-effective manufacturing processes. In this review paper, we present an overview of the current state of ASSB research, including recent progress in solid-state electrolyte and cathode/anode materials, and cell architecture. We also summarize the recent advancements and highlight the remaining challenges in ASSB research, with an outlook on the future of this promising technology.