• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.24-31
• /
• 2021

The soundproof tunnels have been generally designed with H-beam girders, and the high weight of H-beam may cause the excessive design of the substructure. To solve this problem, this paper proposes a new soundproof tunnel girder design composed of pipes and discontinuous plates. First, the structural behavior of the straight girder according to the design parameters was examined through finite element analysis. The arrangement and shape of the plates were determined as the design parameter, to obtain the optimal design of girder. After then, the structural behavior and buckling stability of the arched girder were subsequently evaluated. As a result of the parameter analysis, it was confirmed that the axial force acting on the girder increased and the moment decreased as the ratio of unsupported sections decreased or the number of supporting plates increased. The stress concentration on the pipe member was relieved by increasing the long axis length of the elliptical plate. Arched girder analysis showed that the structural efficiency increase as the long axis of elliptical plate increase. As a result of the buckling evaluation, the buckling threshold load of the three connected girders was about 3.7 times higher than the design load. Consequently, it was confirmed that the proposed soundproof tunnel structure design satisfies both light weight and structural safety.

• Journal of Korea Water Resources Association
• /
• v.55 no.12
• /
• pp.1137-1147
• /
• 2022

River and groundwater stages are the main elements in the hydrologic cycle. They are spatially correlated and can be used to evaluate hydrological and agricultural drought. Stochastic simulation is often performed independently on hydrological variables that are spatiotemporally correlated. In this setting, interdependency across mutual variables may not be maintained. This study proposes the Bayesian vector autoregression model (VAR) to capture the interdependency between multiple variables over time. VAR models systematically consider the lagged stages of each variable and the lagged values of the other variables. Further, an autoregressive model (AR) was built and compared with the VAR model. It was confirmed that the VAR model was more effective in reproducing observed interdependency (or cross-correlation) between river and ground stages, while the AR generally underestimated that of the observed.

• Journal of Korean Library and Information Science Society
• /
• v.53 no.2
• /
• pp.215-239
• /
• 2022

All public libraries are local public goods and cultural infrastructures whose ideological pillars are publicly operated, free, and open to all. This identity is justified when the public library provides various knowledge information, various programs, and community space to local residents within the service area, and ultimately contributes to the cultural development of the nation and society. To this end, the country and local governments must expand the number of individuals that meet legal standards, deploy competent professionals, and provide facilities and spaces that are easy to access and use. However, if there is a gap in infrastructure and services between regional public libraries, it causes inequality in access and use of residents, which inevitably leads to information gap and cultural welfare gap. Therefore, this study was analyzed the relative gap using the location quotient, key infrastructure indicators and service indicators of public libraries of regional government in Korea and basic local government in the Chungnam region from the viewpoint that the balanced development and capacity building of public libraries must precede the establishment of a public library in Chungnam region as a life-friendly knowledge information service institution, culture enjoyment and lifelong learning space. Based on the results, a method to resolve the gap was suggested by dividing the elements of gaps in public libraries into accessibility, core infrastructure, and services, focusing on vulnerable cities and counties in the Chungnam region.

• Journal of Applied Biological Chemistry
• /
• v.65 no.4
• /
• pp.343-348
• /
• 2022

This study was performed to establish an analytical method for the standardization of Angelicae Dahuricae Radix as a functional ingredient. We established six compounds including oxypeucedanin hydrate (1), byakangelcol (2), oxypeucedanin (3), imperatorin (4), phellopterin (5) and isoimperatorin (6) as marker compounds of Angelicae Dahuricae Radix. An analytical method using Ultra Performance Liquid Chromatography (UPLC) was established and validated for marker compounds of Angelicae Dahuricae Radix. The specificity was confirmed by the chromatogram from UPLC and the value of coefficient determination was also higher than 0.999, indicating high linearity. The relative standard deviation (RSD) and recovery of marker compounds were less than 5% and in the range of 90- 110%, respectively, which means that this method has high accuracy and precision. Therefore, this analytical method could be used as basic data for the development of functional ingredients for health functional food of Angelicae Dahuricae Radix.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.2
• /
• pp.153-164
• /
• 2023

The objective of this study is to examine the removal rate of air pollutants, specifically sulfur oxides (SO_x) and nitrogen oxides(NO_x), using concrete permeable blocks containing zeolite beads coated with materials capable of eliminating these pollutants. Titanium dioxide(TiO₂) powder and coconut shell powder were utilized for the removal of SO_x and NO_x and were applied as coatings on the zeolite beads. Concrete permeable block specimens embedded with the coated zeolite beads were produced using an actual factory production line. Test results demonstrated that the concrete permeable block containing zeolite beads coated with coconut shell powder in the surface layer achieved SO_x and NO_x removal rates of 12.5% and 99%, respectively, exhibiting superior performance compared to other blocks. Additionally, the flexural strength and slip resistance were 5.3MPa and 65BPN or higher, respectively, satisfying the requirements specified in KS F 4419 and KS F 4561. Conversely, the permeability coefficient exhibited low permeability, with grades 2 and 3 before and after contaminant pollution, according to the standard for 'design, construction, and maintenance of pavement using permeable block'. In conclusion, incorporating zeolite beads coated with coconut shell powder in the surface layer enables simultaneous removal of SO_x and NO_x, irrespective of ultraviolet rays, while maintaining adequate flexural strength and slip resistance. However, the permeability is significantly reduced, necessitating further improvements.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.11
• /
• pp.77-85
• /
• 2007

This paper investigates the mechanical characteristics of composite geo-material which was developed to reuse both dredged soils and bottom ash. The composite geo-material used in this experiment consists of dredged soil taken from the construction site of Busan New Port, cement, air foam and bottom ash. Bottom ash is a by-product generated at the Samcheonpo thermal power plant. Several series of laboratory tests were performed to investigate behavior characteristics of composite gee-material, in particular the reinforcing effect by mixing bottom ash. The experimental results of composite geo-material indicated that the stress-strain relationship and the unconfined compressive strength are strongly influenced by mixing conditions. Especially it was observed that the compressive strength of composite geo-material increased with an increase in bottom ash content due to reinforcing effect by the bottom ash. Compressive strength of composite geo-material increased with the increase in curing time. The 28-day strength of composite geo-material is $1.7{\sim}1.8$ times higher than the 7-day strength. The moist unit weight strongly depended on air-foam content as well as bottom ash content added to the composite goo-material. In composite geo-material, secant modulus ($E_{50}$) also increased as its compressive strength increased due to the inclusion of bottom ash.

• Korean small business review
• /
• v.41 no.4
• /
• pp.65-86
• /
• 2019

This study empirically analyzed how the elements of entrepreneurship and the fear of entrepreneurial failure influence entrepreneurial intention with each other in a situation that encourages startups. In particular, the moderating effect of fear of entrepreneurial failure was verified by dividing the fear of entrepreneurial failure into three sub-variables: fear of financial loss, fear of psychological loss, and fear of career loss. As a result, it was found that proactiveness and risk-taking had a positive effect on entrepreneurial intention, but innovativeness did not. Fear of entrepreneurial failure(all of sub-variables) was found to have no significantly moderating effect on the relationship between entrepreneurship and entrepreneurial intention. Therefore it seemed to have a negative effect as a independent variable. However, considering the regression coefficient(β) is positive or negative depending on the interaction terms of the sub-variables of fear of entrepreneurial failure and the entrepreneurship, it could be inferred that the moderating effect could be positive or negative. Based on this research results, a sophisticated entrepreneurship education program to inspire entrepreneurship and lower the fear of failure is needed in order to promote startups. And at the same time, a social safety net construction plan to reduce the fear of entrepreneurial failure needs to be prepared.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.4
• /
• pp.223-228
• /
• 2023

This study examines the relationship between teacher-perceived teaching efficacy and happiness and teacher-infant interaction, and analyzes the effect of teaching efficacy and happiness on teacher-infant interaction. The purpose was to reveal that it was an important variable in the quality of action. Frequency analysis and descriptive statistics analysis were conducted for the Korean Children's Panel 7th year (2014) data, and Pearson's moment-moment correlation coefficient was calculated for correlation analysis between variables. Multiple regression analysis was conducted to examine the influence of teachers' teaching efficacy and happiness on teacher-infant and infant-infant interactions. The research results were as follows. First, teachers' teaching efficacy, teacher happiness, teacher-infant, and infant-infant interactions were all found to have significant positive correlations. Second, teachers' teaching efficacy was found to have a significant effect on teacher-infant and infant-infant interactions, and the influence increased when teacher's happiness was added. Therefore, we need to come up with a plan to increase teachers' teaching efficacy and teacher happiness at the same time so that the quality of teacher-infant and infant-infant interactions can be meaningfully improved.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.1
• /
• pp.21-32
• /
• 2023

Interrill erosion dominates in forest areas, and the erosion rate in surface-disturbed areas is significantly increased by the development and expansion of rill. In this study, soil erosion experiments using simulated rainfall and inflow were performed to understand the development and the micromorphological changes of rill on steep slopes. The characteristic factors of the micromorphology, such as the rill cross section, rill volume, rill density, rill order, and rill sharpness, were analyzed according to steepness and location (upper or lower) of slope. The head-cut of the simultaneous incised rills by rainfall simulation moved rapidly upslope, and the randomly developed rills expanded deeply and widely with their connection. The rill cross section evolved to downslope gradually increased. The rill volume occupied about 78 % of the sediment volume, confirming that the contribution of the sediment from the rill erosion is greater than that of the interrill erosion. Although the rate of increase in rill order slowed as the slope increased, the total length and density of the rill generally increased. As the slope increased from 15° to 20°, the bed incision of rills became larger than the sidewall expansion, and the rill sharpness increased by 1.6 times. The runoff coefficient on the lower slope decreased by 12.3 % than that on the upper slope. It was evaluated that the subsoil exposures and formation changes by the rill expansion increased the infiltration rate. Although the sediment accompanying the rills generally increased with slope increase, it was directly influenced by the hydraulic velocity of enhanced rill with the local convergence and expansion in the process of the rill evolution.

• Analytical Science and Technology
• /
• v.19 no.2
• /
• pp.142-148
• /
• 2006

To determine malachite green and leuco-malachite green residues in sea food, a liquid chromatographic method has been optimized. The target compounds were extracted in the homogenized edible tissues with a mixture of McIlvaine buffer-acetonitrile and partitioned against dichloromethane. After concentrating the lower layer, the resulting residues were re-dissolved in methanol and analyzed by the HPLC with visible detector at 620 nm using acetonitrile-acetate buffer. For the analysis of leuco-malachite green with malachite green simultaneously, post-column packed with lead(IV) oxide was used for oxidizing leuco-malachite green to malachite green. The correlation coefficients($r^2$) was 0.9989 for malachite green, and 0.9995 for leuco-malachite green. The limit of detection was 0.005 mg/kg for the combined of malachite green and leuco-malachite green at signal/noise${\geq}3$. The recovery rate was within a reliable range of 84~98% (CV 3~16%). Leuco-malachite green were detected in carp and crusian carp.