• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.6 no.5
• /
• pp.337-345
• /
• 2016

There is an increasing attention on the sustainable energy in the world as the problem of fossil energy exhaustion and environmental issues appear. This paper addresses technologies and industries related to hydrogen energy in the literature, and develops strategy for the preparation of hydrogen energy infrastructure in Korea by extracting several factors suitable for SWOT analysis after reviewing literature. Research articles and reports about the practical application of hydrogen energy in the literature were investigated and seventy evaluation factors were extracted. Then, survey to eliminate the unsuitability problems of duplication, disproportion and objectivity was performed by scholars and experts in research institutes. Finally, sixteen factors consisting of 4 strength factors, 4 weakness factors, 5 opportunity factors and 4 threat factors were determined as the strategic factors for the infrastructure of hydrogen energy industry.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.2D
• /
• pp.183-190
• /
• 2009

In order to improve continuous success and stabilization of high-speed rail in the future, Using Frequency of high-speed rail should be enhanced by improving satisfaction of high-speed rail passenger. High-speed rail is needed to hold the priority in competition means by comparing the traits of service of domestic air lines. This study utilizes structural equation modeling to develop model for estimating factors influencing to service through conducting survey questionnaire. It also uses reliability analysis, correlation analysis, factor analysis to examine the rationalization of items and to establish hypothesis of this research. The results show that KTX contains 'inner service' item that is considered to be ameliorated and that domestic airline present low performance of 'outer service' item. In other words, moving section which partly is under a limited condition is needed to be improved. In addition, access to airport and transfer to other transportations have to be improved as they show the lowest satisfaction.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2A
• /
• pp.171-178
• /
• 2008

The object of this study is to propose a rate of vibration increase in the analysis of temporary rail non-fixed in the vertical direction and characterize the nonlinear dynamic behavior of temporary rail while considering longitudinal and latitudinal load, vibration and lifting. The rate of vibration increase is proposed through measurement of an actual structure that is largely affected by loading and vibration of the superstructure. Dynamic behavior was additionally characterized by the dynamic response resulting from nonlinear dynamic finite element analysis with vehicle loading, including the rate of vibration increase. As a result, the rate of vibration increase by the vibration of an Auto Bar Machine is determined as 7% and the maximum stress in the analysis of the nonlinear rail is increased 14.5% over that of linear rail, and temporary rail is shown to be very sensitive to the velocity of the superstructure.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.4D
• /
• pp.523-533
• /
• 2009

The purpose of the present study is to examine the dynamic interaction characteristics between moving maglev vehicle and guideway bridge system. For this purpose, the dynamic governing equation of 2-dof maglev vehicle using optimal feedback control scheme of LQG was derived with or without consideration of the dynamic interaction between vehicle and guideway bridge system. From the parametric study, it was found that the dynamic interaction effect between bridge and vehicle was large in case of neglecting the railway roughness effect. But if the railway roughness effect was considered, it was observed two analysis results with or without consideration of the dynamic interaction did not show big difference. As a conclusion, it is required to take into account the dynamic interaction effect of bridge and maglev vehicle and the railway roughness for precise evaluation of runnability of maglev vehicle and impact factor of guideway.

• Steel and Composite Structures
• /
• v.49 no.4
• /
• pp.457-471
• /
• 2023

To make up for the performance weaknesses of recycled aggregate concrete (RAC), expand the application range of RAC, and alleviate the environmental problems caused by excessive exploitation of natural coarse aggregates (NCA), this study proposes a basalt fiber-reinforced recycled aggregate concrete (BFRRAC)-filled square steel tubular columns that combines two modification methods of steel tube and fiber, which may greatly enhance the mechanical properties of RAC. The axial compression performance for BFRRAC-filled square steel tubular columns was reported during this study. Seven specimens with different replacement ratios of recycled coarse aggregate (RCA), length-diameter ratios, along with basalt fiber (BF) contents were designed as well as fabricated for performing axial compression test. For each specimen, the whole failure process as well as mode of specimen were discovered, subsequently the load-axial displacement curve has obtained, after which the mechanical properties was explained. A finite element analysis model for specimens under axial compression was then established. Subsequently, based on this model, the factors affecting axial compression performance for BFRRAC-filled square steel tubes were extended and analyzed, after which the corresponding design suggestion was proposed. The results show that in the columns with length-diameter ratios of 5 and 8, bulging failure was presented, and the RAC was severely crushed at the bulging area of the specimen. The replacement ratio of RCA as well as BF content little affected specimen's peak load (less than 5%). As the content of BF enhanced from 0 kg/m³ to 4 kg/m³, the dissipation factor and ductility coefficients increased by 10.2% and 5.6%, respectively, with a wide range.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.6
• /
• pp.811-819
• /
• 2023

Understanding the local conditions is a crucial factor in enhancing the success potential of overseas construction projects. This can be achieved through the analysis of news articles of the target market using topic modeling techniques. In this study, the authors aimed to analyze news articles using two topic modeling methods, namely Latent Dirichlet Allocation (LDA) and BERTopic, in order to determine the optimal approach for market condition analysis. To evaluate the alignment between the generated topics and the actual themes of the news documents, the research collected 6,273 BBC news articles, created ground truth data for individual news article topics, and finally compared this ground truth with the results of the topic modeling. The F1 score for LDA was 0.011, while BERTopic achieved a score of 0.244. These results indicate that BERTopic more accurately reflected the actual topics of news articles, making it more effective for understanding the overseas construction market.

• Journal of Wetlands Research
• /
• v.21 no.2
• /
• pp.102-113
• /
• 2019

Slack-tide sampling was carried out at 6 stations at high and low tide for a tidal cycle during spring tide of the early summer (June) and summer (July, August) of 2016 to determine the difference of water quality according to tide in Masan Bay, Korea. The mixing regime of all the water quality components investigated was well explained through the correlation with SAL. In the early summer and summer, TURB, DSi and NNN which mainly flow into the bay from the streams and SS, COD, AMN and $H_2S$ which mainly indicate the internal sink and source materials have a property of conservative mixing and non-conservative mixing, respectively. The conservative mixing showed a good linear relationship of the water quality between high and low tide, and the non-conservative mixing showed a variation of different pattern each other. Factor analysis performed on the concentration difference data sets between high and low tide helped in identifying the principal latent variables for them. In early summer, multiple effects (tidal action, natural influx and internal sinks and sources etc.) acted in combination for the differences to be distributed evenly in four factors (VF1~4), since there were few allochthonous inputs as a low-water season. On the contrary, in summer, the parameters showing large concentration difference at ST-1 affected by stream water were concentrated in one factor (VF1) and clearly distinguished from the parameters affected by the internal sinks and sources. In fact, there is no estuary (bay) that always maintains steady state flow conditions. The mixing regime of an estuary might be changed at any time due to the change of flushing time, and furthermore the change of end-member conditions due to the internal sinks and sources makes the occurrence of concentration difference inevitable. Therefore, when investigating the water quality of the estuary, it is necessary to take a sampling method considering the tide to obtain average water quality data.

• The Journal of Engineering Geology
• /
• v.30 no.4
• /
• pp.617-634
• /
• 2020

The purpose of this study is to investigate the relationship of between earthquakes and fluctuation of water level in a groundwater well of the active-fault zone and 124 national groundwater monitoring wells in Gyeongju area. The spatial and temporal relationships between the fluctuation of water level and the earthquake were analyzed by the calculation of earthquake effectiveness (ε) and q-factor which are the function of earthquake magnitude and distance from epicenter. Two earthquake events of E1 (April 22, 2019, M 3.8) and E2 (June 11, 2019, M 2.5) show a close relationship with a post-seismic 83 cm decrease and a pre-seismic 76 cm increase in water level at the active fault zone of Dangu-ri, respectively. The spatial analysis of water level fluctuation data in National Groundwater Monitoring Networks caused by earthquake events shows a more distinct response in deep groundwater around fault zones than other area, and a greater change in deep groundwater than shallow groundwater. It's inferred that the decrease and increase in groundwater level are affected by the expansion of fractures and compression of rock mass due to seismic stress, respectively. The effective ranges of ε-value and q-factor of the monitoring well in Dangu-ri were calculated as 2.70E-10~5.60E-10 and 14.4~18.0, respectively.

• Economic and Environmental Geology
• /
• v.34 no.3
• /
• pp.283-299
• /
• 2001

The middle cover soils and clay liners collected from the Kumheung landfill in Gongiu City were analysed for As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti and Zn concentrations using 0.] N HCl digestion and total/sequential extraction experiments followed by ICP-AES determination. The uncontaminated soil and sediment samples were also analyzed for the comparison. The results of sequential extraction showed that Cu was dominant in the oxidizable fraction, and As, Ni, Sr, Ba, and Mn were in the exchangeable fraction. Zinc and Mn occurred mostly in association with reducible, residual and carbonate fractions. Most of Cd and Pb were bound to the reducible and oxidizable fractions. The main carrier of Co, Cr, Fe and 11 was the residual fraction and another important carrier was the reducible fraction. The percentage of the metals of organically-bound form in the middle cover soils and clay liner was in the order of Cu(48%) > Ti(42%) > Pb(27%) > As(25%) > Cd(20%). As deduced from sequential extraction analysis, potential order of metal mobility in the middle cover soils and clay liner from the landfill was proposed: Cd > Sr > As > Ni > Mn > Ba > Cu > Pb > Zn » Co > 11 > Fe > Cr. Based on the 'geoaccumulation index' and the 'enrichment factor' normalized to A], the level of contamination of Cu, Ni and C1' was significant in the samples from Kumheung landfill and surrounding farmland. Their enrichments were attributed partly to anthropogenic pollutions.

• Korean Chemical Engineering Research
• /
• v.53 no.6
• /
• pp.730-739
• /
• 2015

108 microorganism types (79 types of fungi and 29 types of bacteria) were isolated from 25 automobiles generating bad odor when the air conditioner was turned on, and 43 types of fungi and 23 types of bacteria were identified. The analysis of condensate generated by the air conditioners in the automobiles indicated pH 6.4~7.1, 12.5~34.2 mg/L carbon source, 0.9~18.6 mg/L nitrogen source, 0.5~27.8 mg/L ion contents, and 0.1~7.7 mg/L mineral contents. The biofilms were formed by the mesophiles under the summer temperature/humidity condition ($26^{\circ}C$, 70% R.H.), and they were regenerated when the environmental factors (nutritional contents and temperature/humidity) were appropriate even after they were artificially removed. Although the antimicrobials removed 99.9% of planktonic cells within 15 minutes, they were not effective in removing biofilm. Up to 1,950 ppmv of ethanol was observed in the automobile treated with the antimicrobials. Although the figure is lower than the acute toxicity level when inhaled by humans, the health safety of the chemical substances used in the antimicrobials needs to be reviewed.