• Journal of the Korean Society of Systems Engineering
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• v.9 no.2
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• pp.7-14
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• 2013

Because submarine is high-technology and very complex system, it takes a lot of time, cost and manpower for design. For efficient concept design, application of systematic method is required such as system engineering. In this study, we studied application method of MBSE for submarine concept design with SWBS (Ship Work Breakdown Structure). Components of submarine system from SWBS were classified and organized as system architecture with 'Vitech CORE'. Through the MBSE application for concept design, systematic, efficient and traceable concept design of submarine was considered.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.2
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• pp.276-284
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• 2003

The preconditioned conjugate gradient method is an efficient iterative solution scheme for large size finite element problems. As preconditioning method, we choose an incomplete Cholesky factorization which has efficiency and easiness in implementation in this paper. The incomplete Cholesky factorization mettled sometimes leads to breakdown of the computational procedure that means pivots in the matrix become minus during factorization. So, it is inevitable that a reduction process fur stabilizing and this process will guarantee robustness of the algorithm at the cost of a little computation. Recently incomplete factorization that enhances robustness through increasing diagonal dominancy instead of reduction process has been developed. This method has better efficiency for the problem that has rotational degree of freedom but is sensitive to parameters and the breakdown can be occurred occasionally. Therefore, this paper presents new method that guarantees robustness for this method. Numerical experiment shows that the present method guarantees robustness without further efficiency loss.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.10
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• pp.853-858
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• 2003

In this study, a new simplified technology for fabricating high density trench gate DMOSFETs using only three mask layers and TEOS/nitride spacer is proposed. Due to the reduced masking steps and self-aligned process, this technique can afford to fabricate DMOSFETs with high cell density up to 100 Mcell/inch$^2$ and cost-effective production. The resulting unit cell pitch was 2.3∼2.4${\mu}$m. The fabricated device exhibited a excellent specific on-resistance characteristic of 0.36m$\Omega$. cm$^2$ with a breakdown voltage of 42V. Moreover, time to breakdown of gate oxide was remarkably increased by the hydrogen annealing after trench etching.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.311-316
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• 2010

According to increase of combined cycle power generation, the manufacturing market of gas turbine generator has become more competitive, so there is high pressure on the manufacturer to reduce generator price. Global VPI(vacuum pressure impregnation) method is effective to save the production cost and time for manufacturing stator windings, but it has an abrasion problem by vibration between stator windings and slots. This paper presents the insulation breakdown case, which is for VPI type generator during high voltage insulation tests, and also shows the cause analysis, repair works as well as reliability test. the purpose of this paper is to understand the insulation properties of VPI type generator and to know prevention of insulation weakness.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.11
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• pp.1-8
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• 2011

One of the most important parameters that limit maximum output power of transistor is breakdown. InAlAs/InGaAs/GaAs Metamorphic HEMTs (MHEMTs) have some advantages, especially for cost, compared with InP-based ones. However, GaAs-based MHEMTs and InP-based HEMTs are limited by lower breakdown voltage for output power even though they have good microwave and millimeter-wave frequency performance with lower minimum noise figure. In this paper, InAlAs/$In_xGa_{1-x}As$/GaAs MHEMTs are simulated and analyzed for breakdown. The parameters affecting breakdown are investigated in the fabricated 0.1-${\mu}m$ ${\Gamma}$-gate MHEMT device having the modulation-doped $In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As$ heterostructure on the GaAs wafer using the hydrodynamic transport model of a 2D commercial device simulator. The impact ionization and gate field effect in the fabricated device including deep-level traps are analyzed for breakdown. In addition, Indium mole-fraction-dependent impact ionization rates are proposed empirically for $In_{0.52}Al_{0.48}As/In_xGa_{1-x}As$/GaAs MHEMTs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2176-2181
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• 2011

This paper estimates the life cycle cost(LCC) of a propulsion control system using the maintenance information in the high speed train(KTX-1). Life cycle costing is one of the most effective approaches for the cost analysis of long-life systems such as the KTX-1. Until now, most life cycle cost of the system has been studied as a whole system viewpoint. But in case of railway industry, LCC studies are needed on the subsystem like a propulsion control system because subsystems are developed continuously localization. This paper proposes the life cycle cost model which fitted to estimate life cycle cost (LCC) using maintenance information manual. As a result, LCC on propulsion control system increased moderately expect for periodical time when major parts are replaced at the same time. Results will be reflected in the development of domestic products.

• Korean Journal of Construction Engineering and Management
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• v.14 no.3
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• pp.88-96
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• 2013

Recent proliferation of building information modeling (BIM) has actively stimulated integrated utilization of geometric (graphic) and non-geometric (non-graphic) data. Nevertheless, physically and logically, linking and maintaining these two different types of data in an integrated manner requires enormous overhead efforts for practical implementation. In order to address this problem, this paper proposes a concept and structure of the object breakdown structure (OBS) that facilitates advanced BIM implementations in an automated and effective manner. Proposed OBS numbering system has secure rules for organizing graphic objects in full considerations of effectively integrating with non-geometric data (e.g. cost and schedule). It also removes repetitive linking process caused by design changes or modifications. The result of applying this concept to a housing project revealed that only 120 definitions controled over 6,000 graphic objects for full integration with cost and schedule functions.

• Advanced Composite Materials
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• v.16 no.2
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• pp.135-149
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• 2007

In the automobile industry, structural health monitoring of fiber reinforced polymer composite parts is a widespread need for maintenance before breakdown of the functional elements or a complete vehicle. High performance sensors are generally used in many of the structural health monitoring operations. Within this study, a carbon fiber sewing thread has been used as a low cost laminate failure sensing element. The experimentation plan was set up according to the electrical conductance and flexibility of carbon fiber threads, advantages of preforming operations, and sewing mechanisms. The influence of the single thread damages by changing the electrical resistance and monitoring the impact location by using carbon thread sensors has been performed. Innovative utilization of relatively cost-effective carbon threads for monitoring the delamination of metallic inserts from the basic composite laminate structure is a highlighting feature of this study.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.199-212
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• 2010

To establish an infrastructure for technology and information in the domestic construction industry, several construction regulations pertaining to construction information have been institutionalized. However, there are major problems with the domestic information classification system, earned value management (EVM) and project management information system (PMIS). In particular, the functions of the current PMIS have consisted of a builder-oriented system, and as EVM is not applied to PMIS, the functions of reporting, analysis and forecast for owners are lacking. Moreover, owners cannot confirm information on construction schedule and cost in real time due to the differences between the EVM and PMIS operation systems. The purpose of this study is to provide a framework that is capable of operating PMIS efficiently under an e-business environment, by providing a proposal on how to establish a work breakdown structure (WBS) and an EVM - PMIS integration model, so that PMIS may provide the function of EVM, and stakeholders may have all information in common. At the core of EVM - PMIS integration is the idea that EVM and PMIS have the same operation system, in order to be an activity-based system. The principle of the integration is data integration, in which the information field of an activity is connected with the field of a relational database table consisting of sub-modules for the schedule and cost management function of PMIS using a relational database management system. Therefore, the planned value (PV), cost value (CV), actual cost (AC), schedule variance (SV), schedule performance index (SPI), cost variance (CV) and cost performance index (CPI) of an activity are connected with the field of the relational database table for the schedule and cost sub-modules of PMIS.

• Korean Journal of Construction Engineering and Management
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• v.8 no.4
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• pp.119-127
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• 2007

Cost and Schedule is the most important information, and how efficiently manage this information is the key issue for Construction Project Management. Domestically, systematic scheduling method such as CPM network is not only used widely but integration of time and cost information also is. In order to effectively integrate and use the time and cost information, it is suggested that WBS(Work Breakdown Structure) based QDB(Quantity Database) should be generated from the design phase and, WBS and QDB related system tool should be supported. It could be helpful to relate and integrate other construction project information.