• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1420-1427
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• 2023

Seismic risk has received increased attention since the 2011 Fukushima accident in Japan. The seismic risk of a nuclear power plant is evaluated via seismic probabilistic safety assessment (PSA), for which several methods are available. Recently, the discrete approach has become widely used. This approximates the seismic risk by discretizing the ground motion level interval into a small number of subintervals with the expectation of providing a conservative result. The present study examines the effect of the number of subintervals upon the results of seismic risk quantification. It is demonstrated that a small number of subintervals may lead to either an underestimation or overestimation of the seismic risk depending on the ground motion level. The present paper also provides a method for finding the boundaries between overestimation and underestimation regions, and illustrates the effect of the number of subintervals upon the seismic risk evaluation with an example. By providing a method for determining the effect of a small number of subintervals upon the results of seismic risk quantification, the present study will assist seismic PSA analysts to determine the appropriate number of subintervals and to better understand seismic risk quantification.

• 환경영향평가
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• 제18권3호
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• pp.143-150
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• 2009

The present study investigates the effects of the flight paths of military aircraft on noise map and its WECPNL(Weighted Equivalent Continuous Perceived Noise Level) distribution. Aircraft noise modeling and simulation have been performed on a Korean military air base by means of INM(Integrated Noise Model) with the input data of airfield location, aircraft specifications, flight paths and aircraft's operation schedules. The result of noise modelling has been verified in comparison with the result of measured noise level. The flight path of military aircraft, as the key parameter of the present study, was modeled by combining takeoff, overfly, approach and touch-and-go modes. The present INM simulations have been conducted for various flight path cases with different takeoff, approach modes and overfly modes. The simulation results showed that the change of flight path can remarkably affect the noise influence region and the WECPNL distribution around the airfield.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1244-1249
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• 2005

Present PII(Private Infrastructure Investment) in Korea has increased up to 11% compared to the year 2003 and is expected to increase in the future. In spite of its rapid increase, we don't have any definite standard or system which distinctly presents the rate of return for domestic PII yet, and practical and scientific research is not sufficient compared to its necessity and importance. Hence, in this study we suggests methods to estimate the rate of return of PII to promote SOC PII to last successfully and present the proper level of rate of return of PII which is appropriate for domestic situations through diverse analysis. Therefore, to present reasonable rate of return, we have used 5 methods: previous research analysis, case study, financial index analysis, analysis of investor's rate of return, and analysis of rate of return in a real estate market. After comparing and analyzing these methods, at the end, we have presented the appropriate level of rate of return of PII, which can be applied in the domestic market.

• Steel and Composite Structures
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• 제20권4호
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• pp.833-849
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• 2016

Pre-stressing of existing structures using steel cables, FRP cables or FRP laminates has been successfully tried in the past. Retrofitting of beams using pre-stressed laminates does not utilize the full strength of the FRP due to de-bonding of the laminates before the fibre fracture. In the present study attempt has been made to overcome this problem by replacing the FRP laminates by the FRP sheets. In the present paper the effect of initial damage level and pre-stress level on strength, stiffness, cracking behaviour and failure mode of girders retrofitted using pre-stressed CFRP sheets has been studied. The results indicate that rehabilitation of initially damaged girders by bonding pre-stressed CFRP sheets improves the flexural behaviour of beams appreciably. However, it has been observed that with increase in pre-stressing force the load carrying capacity of the girders increases up to a particular level up to which the mode of failure is fibre fracture. Thereafter, the mode of failure shifts from fibre fracture to de-bonding and there is no appreciable increase in load carrying capacity with further increase in pre-stressing force.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.349-352
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• 2008

This study has numerically modeled the combustion processes of the turbulent swirling premixed lifted syngas flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially-injected air jets induce the turbulent swirling flow which plays the crucial role of stabilizing the turbulent lifted flames. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flamelet model. Numerical results indicate clearly that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling premixed lifted flames in the low-swirl burner. Computations are made for the wide range of the syngas chemical composition and the dilution level at two pressure conditions (1.0, 5.0 bar). Numerical results indicate that the lifted height in the LSB is increased by decreasing the H2 percentage and increasing the dilution level at the given equivalence ratio. It is also found that the flashback is occurred for the hydrogen composition higher than 80% at the equivalence ratio, 0.8. However, at the syngas composition range in the IGCC system, the stable lean-premixed lifted flames are formed at the low-swirl burner.

• 한국치위생학회지
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• 제12권6호
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• pp.1158-1164
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• 2012

Objectives : The aim of the present study was to measure the level of Streptococcus mutans(S. mutans), the major causative agent in dental caries, and to examine the relationship between S. mutans level and dental caries experience. Methods : The present study was carried out in 41 university students. S.mutans plaque was detected in the saliva using Dentocult$^{(R)}$-SM and was measured in absorbance. The data were analyzed in the relevance for number of dental caries experience. Results : The group of S. mutans value has progressive caries, which was higher than that of non-suffering caries(p<0.05). More caries experience showed higher value of S. mutans(p>0.05). According to the relationship with DMFT, level of S. mutans and absorbance, correlation with the level of salivary S. mutans is shown statistically highly significant (p<0.01). The level of S. mutans in saliva and plaque and absorbance is statistically significant(p<0.05). Conclusions : The levels of S. mutans in both group of high caries experience and progressive caries was highly detected, continuous oral health management should be carried out to prevent the possible dental caries.

• Environmental Engineering Research
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• 제25권1호
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• pp.43-51
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• 2020

The present study was designed to characterize the bioaccumulation of organochlorine pesticides (OCPs) in marine organisms (zooplankton, oyster, crab, and goby) on different trophic level. In the present study, sedentary bivalve (oyster) showed strong correlations in OCPs levels with surface sediment in the study area. This indicates the two compartments can be used as alternative for pollution monitoring of OCPs even in narrow scale in space. Bioaccumulation and trophic transfer of OCPs was strongly associated with their hydrophobicity (i.e., K_OW). HCHs with log K_OW < 5 did not show any enrichment through food-chain. However, log BAF values of OCPs with log K_OW > 5 positioned over the 1:1 lines of log BAF and log K_OW of the top predator, indicating the greater fugacities in the higher trophic level and thus the occurrence of biomagnification via ingestion. Based on trophic transfer factors (TTF), more hydrophobic OCPs with log K_OW > 5 were enriched by several to several ten times in the highest trophic level relative to the lowest trophic level. This finding can be used in the establishment of marine environmental water quality criteria by considering biomagnification factors (TTF in this study) of OCPs.

• The International Journal of Costume Culture
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• 제4권3호
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• pp.229-240
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• 2001

The purpose of the present study was to analyze the acceptance level of forecasted information of casual wear in tate 1990s in Korea and the way of utilizing fashion trends information by casual wear industries. The Present study was implemented by content analysis and descriptive survey using questionnaire and interview. Trends information in fashion journals published by fashion institute and articles in daily newspapers were analyzed in terms of fashion image, color, fabric, and silhouette. The data collected from questionnaire and interview with 113 fashion specialists were analyzed through frequency, percentage. The results indicated that among the forecasted information regarding fashion image, romantic and feminine images showed a high level of acceptance to national brand women's casual wear in the late 1990s, while mannish image showed a low level of acceptance. For men's casual wear in the same time period, androgynous trends appeared most frequently, not only in forecasted information, but also in actual trend. it was forecasted that yellow, white, and gray would be in trend and those colors appeared frequently in actual trend. On the other hand pastel tone appeared much more frequently than forecasted. Natural, thin - transparent (S/S) and stretch fabrics (F/W) were in actual trend as it was forecasted. Fit and Pare (woman), and long and slim (man) silhouettes were in actual trend as if was forecasted, but barrel silhouette appeared only in forecasted information. Most of the information forecasting fashion trends for next season were applied to the product planning of the season, right after the information comes out.

• 한국전산유체공학회지
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• 제20권1호
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• pp.16-25
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• 2015

The present study investigates the sloshing phenomena in a two-dimensional rectangular tank at a low filling level by using a level set method based on finite volume method. The code validations are performed by comparing between the present results and previous numerical and experimental results, which gives a good agreement. Various excitation frequencies and excitation amplitude of the 30% filling height tank have been considered in order to observe the dependence of the sloshing behavior on the excitation frequency and amplitude. Regardless of excitation amplitude, the maximum value of wall pressure occurs when the excitation frequency reaches the natural frequency. The time sequence of free surface and corresponding streamlines for excitation frequencies have been presented to analysis the variation of wall pressure according to time, which contributes to explain the double peaks in the time variation of wall pressure.

• Journal of Korean Neurosurgical Society
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• 제47권2호
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• pp.151-154
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• 2010

The efficacy of spinal cord stimulation (SCS) for treatment of various chronic painful conditions is well established. Very few reports have documented the use of SCS for treatment of chronic pain after spinal cord injury. We present a case showing a good outcome after such treatment, and suggest that high cervical stimulation may be efficacious. A 53-year-old male underwent SCS on the C1-3 level for treatment of intractable neuropathic pain below the T3 level, and in the upper extremities, arising from spinal cord injury resulting from transverse myelitis caused by schistosomiasis. High cervical SCS significantly improved the pain in the upper extremities and at the T3-T10 dermatome level. The patient continues to report excellent pain relief 9 months later. The present case suggests that high cervical stimulation may improve chronic pain in the upper extremities and the T3-T10 dermatome level arising from spinal cord injury.