• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.885-896
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• 2013

2,3-Butanediol (2,3-BDO) has immense industrial applications. Recently, microbial fermentation has emerged as an alternative way to produce this industrially important chemical. Although 2,3-BDO is produced by several microorganisms, the Klebsiella genera has an excellent production compared with other 2,3-BDO-producing microorganisms. In order to produce 2,3-BDO on a large scale, the challenges of removing pathogenic factors from Klebsiella pneumoniae need to be addressed. K. pneumoniae produces a number of virulence factors that contribute to its pathogenesis, including lipopolysaccharides, capsules, fimbrial adhesins, etc. Removal of these pathogenic factors from 2,3-BDO-producing Klebsiella strains will result in avirulent strains for the safe, economic, and efficient production of 2,3-BDO. In this review, we summarize the current trends in 2,3-BDO production using K. pneumoniae and insights into the removal of its virulence factors for industrial applications.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.2
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• pp.3-13
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• 2020

The purpose of this study was to analyze the factors negatively affecting college life, to investigate the perception gap between housing types, and to generate preliminary data for increasing residential satisfaction of students who live in temporary housing(e.g., dormitory or one-room). The utilized research methods included a questionnaire survey and an in-depth interview. The college students, especially from other regions, experienced more financial difficulties than others. They managed their tuition and living expense/allowance by parents supports and other sources(e.g., scholarship, arbeit, work in college, loan etc.). The reasons to choose dormitory, as temporary housing, were short distance to college and low costs. In case of one room, independent life was main reason to choose. Gender differences affected to the decision, moving away from present temporary housing. For example, male students preferred an independent life and a short commuting distance, while female students preferred an independent life and a safe life. Thus, considering the origin and gender differences of residents, dormitory planning needed to develop plans allowing independent life and to choose appropriate site for the purpose. In case of planning one room apartment, concerns for safety and landscape were more important than other factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1012-1020
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• 2006

The crack that occurs on the wheels of railroad cars can be categorized into a surface crack that starts from the surface or a subsurface crack that starts from the inside and can be detrimental to safe railroad operations. Therefore, estimating the growth life span of this type of crack is very important. In this research, the stress distributions, displacements, and the growth-life spans of both surface cracks and subsurface cracks have been studied. By using the finite element analysis, especially in the life span prediction process, the stress conditions and the stress intensity factors of the crack tip have been discovered. The Paris formula has been used to analyze the growth-life span prediction.

• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.29-35
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• 1999

At the design of Mark III membrane type LNG tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds are very important in order to assist designers and surveyors. In this study, fatigue tests of lap weld of Mark III membrane type LNG tank were carried out and cumulative damage factor was calculated in order to estimate the fatigue life by probability density function and rule methods. It contained the following tests and reviews : 1) The fatigue tests of lap weld of stainless steel according to statistical testing method recommended by JSME, 2)Preparation of S-N curve for lap welds considering the statistical properties of the results of fatigue tests. 3) Procedure for estimating the initiation life of fatigue crack of lap welds under variable loads by the rule lf classification society and probability density function, 4) Guideline for inspection of lap welds fo membrane type LNG tank.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.28-33
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• 2018

The automotive front bumper guard is the most important part of the vehicle for protecting the life of driver when a traffic accident happens. In order to ensure safe driving, this part must possess sufficient strength and durability. This study was carried out with structural and fatigue analyses by designing front bumper guard models. After the lowest value for maximum total deformation and equivalent stress was found through structural analysis and the highest value for fatigue life was found for all three models, it was shown that the type C front bumper guard model was the most suitable for application to a real car. The strength property and durability of the optimum design were determined through this study's results.

• Structural Engineering and Mechanics
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• v.9 no.6
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• pp.557-568
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• 2000

As time-variant reliability approaches become increasingly used for service life prediction of the aging infrastructure, the demand for computer solution methods continues to increase. Effcient computer techniques have become well established for the reliability analysis of structural systems. Thus far, however, this is largely limited to time-invariant reliability problems. Therefore, the requirements for time-variant reliability prediction of deteriorating structural systems under time-variant loads have remained incomplete. This study presents a computer program for $\underline{REL}$iability of $\underline{T}$ime-Variant $\underline{SYS}$tems, RELTSYS. This program uses a combined technique of adaptive importance sampling, numerical integration, and fault tree analysis to compute time-variant reliabilities of individual components and systems. Time-invariant quantities are generated using Monte Carlo simulation, whereas time-variant quantities are evaluated using numerical integration. Load distribution and post-failure redistribution are considered using fault tree analysis. The strengths and limitations of RELTSYS are presented via a numerical example.

• Journal of the Korean Society for Railway
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• v.8 no.6 s.31
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• pp.544-549
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• 2005

Nowadays, most of bridge networks are complete or close to completion. The biggest challenge railroad./highway agencies and departments of transportation face is the maintenance of these networks, keeping them safe and serviceable, with limited funds. To maintain the bridges effectively, there is an urgent need to predict their remaining life from a system reliability viewpoint. And, it is necessary to develop the maintenance models based on system reliability concept. In this paper, maintenance models are developed for preventive maintenance and essential maintenance by using system reliability and lifetime distributions. The proposed model is applied to an existing railroad bridge. The optimal maintenance strategy of this bridge is obtained in terms of services life extension and cumulative maintenance cost.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3517-3527
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• 2021

New 80-MW (electric) ultra-long-life sodium cooled fast reactor core having inherent safety characteristics is designed with heterogeneous fuel assemblies comprised of driver and blanket fuel rods. Several options using upper sodium plenum and SSFZ (Special Sodium Flowing Zone) for reducing sodium void reactivity are neutronically analyzed in this core concept in order to improve the inherent safety of the core. The SSFZ allowing the coolant flow from the peripheral fuel assemblies increases the neutron leakage under coolant expansion or voiding. The Monte Carlo calculations were used to design the cores and analyze their physics characteristics with heterogeneous models. The results of the design and analyses show that the final core design option has a small burnup reactivity swing of 618 pcm over ~54 EFPYs cycle length and a very small sodium void worth of ~35pcm at EOC (End of Cycle), which leads to the satisfaction of all the conditions for inherent safety with large margin based on the quasi-static reactivity balance analysis under ATWS (Anticipated Transient Without Scram).

• Earthquakes and Structures
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• v.25 no.1
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• pp.69-78
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• 2023

Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.

• Spatial Information Research
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• v.21 no.6
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• pp.43-55
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• 2013

Recently, the research to visualize and to reproduce evacuation situations such as terrorism, the disaster and fire indoor space has been come into the spotlight and designing a model for interior space and reliable analysis through safety evaluation of the life is required. Therefore, this paper aims to develop simulation model which is able to suggest evacuation route guidance and safety analysis by considering the major risk factor of fire in actual building. First of all, we designed 3D-based fire and evacuation model at a subway station building in Incheon and performed fire risk analysis through thermal parameters on the basis of interior materials supplied by Incheon Transit Corporation. In order to evaluate safety of a life, ASET (Available Safe Egress Time), which is the time for occupants to endure without damage, and RSET (Required Safe Egress Time) are calculated through evacuation simulation by Fire Dynamics Simulator. Finally, we can come to the conclusion that a more realistic safety assessment is carried out through indoor space model based on 3-dimension building information and simulation analysis applied by safety guideline for measurement of fire and evacuation risk.