• Architectural research
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• v.8 no.1
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• pp.57-68
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• 2006

Global competition and reduced project life cycle ultimately puts greater performance requirements on the capital project delivery systems used to maintain competitiveness. Despite continuing improvements in delivery cycle time, business owners of facilities continue to demand greater improvements in project delivery cycle time. Therefore, it is very important to investigate the various techniques and methods leading to reduction in project cycle time and also identify the applicability of identified techniques and methods. This paper introduces reduction techniques identified through literature review (i.e, Schedule Reduction Techniques (SRTs), Management Techniques (MTs), and Construction Institute Industry (CII) Best Practices (BPs). In order to collect applicability of these techniques under different project phases (Pre-project planning (PPP), Design (D), Material Management (MM), Construction (C), and Start-up (SU)), the Essence Applicability Matrices (EAM) is used.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1225-1226
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• 2005

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.155-163
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• 2019

Mixture electrodes of a graphite having a good cycle performance and a silicon monoxide (SiO) having a high capacity are fabricated and their cycle performances are evaluated as negative electrodes for lithium-ion batteries. The electrode prepared by mixing the natural graphite and carbon-coated SiO in a mass ratio of 9:1 shows a reversible capacity of $480mAh\;g^{-1}$, 33% higher than that of graphite. However, the capacity deteriorates continuously upon cycling due to the volume change of silicon monoxide. In this study, the factors that can improve the cycle performance have been discussed through the change in the configurations of the electrode and the electrolyte. The electrode using the carboxymethyl cellulose (CMC) binder shows the best cycle performance compared to the conventional binders. The electrode sing the CMC and styrene-butadiene rubber (SBR) binder not only has almost the similar cycle characteristics with the electrode using the CMC binder but also has the better rate capability. When the fluoroethylene carbonate (FEC) is used as an electrolyte additive, the cycle life is improved. However, the electrolyte with 5 wt% of FEC is appropriate because the rate capability decreases when the content of FEC is increased to 10 wt%. In addition, when the mass loading of the electrode is lowered, the cycle performance is greatly improved. Also, enhanced cycle performance is achieved using the roughened Cu current collector polished by abrasive paper.

• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.197-202
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• 2014

Positive plate was composed of lead hydroxide via reaction between lead oxide and $H_2O$ and lead sulfate was formed of the reaction of lead hydroxide with sulfuric acid. And its density is $3.8g/cm^3$, $4.0g/cm^3$, $4.2g/cm^3$ and $4.4g/cm^3$ by controlling volume of refined water. Curing of positive plate is done for low ($45^{\circ}C$, 40hr, over 95% of relative humidity) & high ($80^{\circ}C$, 40hr, over 95% of relative humidity) temperature, which created 3BS & 4BS active materials. Experimental result of DOD with 100% life cycle test shows that it was not related to the density of active materials but to the low & high temperature aging of active materials. The test makes us to understand that the crystallization which is made by curing of active materials is a more of a main factor than density of active materials under the deep cycle using circumstances. The active materials which were from the high temperature curing are better for deep cycle performance.

• Earthquakes and Structures
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• v.7 no.3
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• pp.271-294
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• 2014

In recent years, along with the advances made in performance-based design optimization, the need for fast calculation of response parameters in dynamic analysis procedures has become an important issue. The main problem in this field is the extremely high computational demand of time-history analyses which may convert the solution algorithm to illogical ones. Two simplifying strategies have shown to be very effective in tackling this problem; first, simplified nonlinear modeling investigating minimum level of structural modeling sophistication, second, wavelet analysis of earthquake records decreasing the number of acceleration points involved in time-history loading. In this paper, we try to develop an efficient framework, using both strategies, to solve the performance-based multi-objective optimal design problem considering the initial cost and the seismic damage cost of steel moment-frame structures. The non-dominated sorting genetic algorithm (NSGA-II) is employed as the optimization algorithm to search the Pareto optimal solutions. The constraints of the optimization problem are considered in accordance with Federal Emergency Management Agency (FEMA) recommended design specifications. The results from numerical application of the proposed framework demonstrate the capabilities of the framework in solving the present multi-objective optimization problem.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.455-464
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• 2020

Reinforcement corrosion is one of the major problems in the durability of reinforced concrete structures exposed to aggressive environments. Deterioration caused by reinforcement corrosion reduces the durability and the safety margin of concrete structures, causing excessive costs in managing these structures safely. This paper aims to investigate the effects of reinforcement corrosion on the load bearing capacity deterioration of the corroded reinforced concrete structures. A new analytical method is proposed to predict the crack growth of cover concrete and evaluate the residual strength of concrete structures with corroded reinforcement failing in bond. The structural performance indicators, such as concrete crack growth and flexural strength deterioration rate, are assumed to be a stochastic process for lifetime distribution modelling of structural performance deterioration over time during the life cycle. The Weibull life evolution model is employed for analysing lifetime reliability and estimating remaining useful life of the corroded concrete structures. The results for the worked example show that the proposed approach can provide a reliable method for lifetime performance assessment of the corroded reinforced concrete structures.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.676-693
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• 2016

Although the methodology and models to assess the economic value of technology assets such as patents are being presented in various ways, there does not exist a structured assessment model which enables to objectively assess a database property's value, and thus there is a need to enhance the application feasibility of practical purposes such as licensing of DB assets, commercialization transfer, security, etc., through the establishment of the valuation model and the life-cycle decision logic. In this study, during the valuation process of DB assets, the size of customer demand group expected and the amount of demand, the size and importance of data sets, the approximate degree of database' contribution to the sales performance of a company, the life-cycle of database assets, etc. will be analyzed whether they are appropriate as input variables or not. As for most of DB assets, due to irregular updates there are hardly cases their life-cycle expires, and thus software package's persisting period, ie. 5 years, is often considered the standard. We herein propose the life-cycle estimation logic and valuation models of DB assets based on the concept of half life for DB usage frequency under the condition that DB assets' value decays and there occurs no data update over time.

• Earthquakes and Structures
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• v.1 no.1
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• pp.69-91
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• 2010

Current seismic design codes do not contemplate explicitly some variables that are relevant for the design of structures subjected to ground motions exhibiting large energy content. Particularly, the lack of explicit consideration of the cumulative plastic demands and of the degradation of the hysteretic cycle may result in a significant underestimation of the lateral strength of reinforced concrete structures built on soft soils. This paper introduces and illustrates the use of a numerical performance-based methodology for the predesign of standard-occupation reinforced concrete ductile structures. The methodology takes into account two limit states, the performance of the non-structural system, and in the case of the life safety limit state, the effect of cumulative plastic demands and of the degradation of the hysteretic cycle on the assessment of structural performance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.779-783
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• 2004

First this paper introduces an advanced FADEC (Full Authority Digital Electric Control) for current and future jet engines.It is designed to realize not only stable thrust control, but also performance improvement, reliability enhancement, service life extension, etc. It can be built by using current micro-processor with high computational power and there exists no difficulties but reliability problem of the micro- processor. Next, the simulation results of SFC minimization control are shown. The target engine is a supersonic, low-bypass ratio, 2-spool, combined cycle turbofan, designated as HYPR90T, which consists of a turbo engine for under Mach 3 flight and a ram engine for over Mach 3 flight. he results can then be used for performance optimization of the engine, which plays important role in the advanced FADEC.

• Clean Technology
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• v.20 no.3
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• pp.241-250
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• 2014

In this study, performance and environmental characteristics of cyclone vacuum cleaners are analyzed and product improvement methods are investigated to minimize environmental effect of the cleaners using the result. A simplified LCA method is used to analyze environmental characteristics of the cyclone vacuum cleaners. Two cyclone vacuum cleaners with similar specifications are chosen for the experiment. Typical characteristics of cyclone vacuum cleaners such as energy consumption, suction force, noise and temperature are measured and compared. Most environmental effect was caused by the energy consumption in use phase of life cycle. Some ideas are created to reduce energy consumption of the vacuum cleaners in use phase like installing baffle, and methods to extend exchange period of filter. It is analyzed how recyclability rate of vacuum cleaners could be improved to reduce the environmental effect in whole life of the vacuum cleaners.