• Structural Engineering and Mechanics
• /
• v.86 no.3
• /
• pp.337-348
• /
• 2023

The optimization of reinforced concrete (RC) cantilever retaining walls is a complex problem and requires the use of advanced techniques like metaheuristic algorithms. For this purpose, an optimization model must first be developed, which involves mathematical complications, multidisciplinary knowledge, and programming skills. This task has proven to be too arduous and has halted the mainstream acceptance of optimization. Therefore, it is necessary to unravel the complications of optimization into an easily applicable form. Currently, the most commonly used method for designing retaining walls is by following the proportioning limits provided by the ACI handbook. However, these limits, derived manually, are not verified by any optimization technique. There is a need to validate or modify these limits, using optimization algorithms to consider them as optimal limits. Therefore, this study aims to propose updated proportioning limits for the economical design of a RC cantilever retaining wall through a comprehensive parametric investigation using the genetic algorithm (GA). Multiple simulations are run to examine various design parameters, and trends are drawn to determine effective ranges. The optimal limits are derived for 5 geometric and 3 reinforcement variables and validated by comparison with their predecessor, ACI's preliminary proportioning limits. The results indicate close proximity between the optimized and code-provided ranges; however, the use of optimal limits can lead to additional cost optimization. Modifications to achieve further optimization are also discussed. Besides the geometric variables, other design parameters not covered by the ACI building code, like reinforcement ratios, bar diameters, and material strengths, and their effects on cost optimization, are also discussed. The findings of this investigation can be used by experienced engineers to refine their designs, without delving into the complexities of optimization.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.5
• /
• pp.5-12
• /
• 2023

Recently, due to urban development and expansion, construction plans have been increasing adjacent to existing tunnel structures such as subways, roads, and large pipelines. Structural plans adjacent to existing tunnels have different effects on tunnel stability depending on the construction method, degree of proximity, and location of new structures. In particular, the pressure water tunnel shows a very large difference from other road tunnels and railway tunnels in geotechnical characteristics and operation characteristics. Therefore, it is necessary to review the safety zone due to adjacent construction in consideration of the geotechnical characteristics of the water tunnel and the new sturure construction method. In this study, the existing tunnel safety zone standards were investigated. A stability evaluation performed numerical analysis considering the deterioration of concrete lining in operation and the characteristics of water tunnel. In addition, the impact of vibration caused by pile construction and blasting excavation of new structures was reviewed. Based on this, a pressure water tunnel safety zone was proposed in consideration of adjacent construction.

• The Korean Journal of Applied Statistics
• /
• v.36 no.1
• /
• pp.63-83
• /
• 2023

Many existing studies have found significant correlations between green spaces, including urban parks, and children's happiness. Furthermore, it was implied that the area/proximity of the urban park would be effective in enhancing infancy happiness. However, inferring causal effects from observed data requires appropriate adjustment of confounding variables, and from this perspective, the causal relationship between the area of urban parks and children's happiness has not been well understood. The causal effect of urban parks on children's happiness was estimated in this study using data from the panel study on Korean children. As methods for adjusting confounding variables, regression adjustment using a regression method, weighting method, and matching method were used, and key concepts of each method were described before the analysis results. Confounders were chosen for the analysis using a directed acyclic graph. In contrast to previous research, the analysis found no significant causal relationship between the size of the city park and children's happiness.

• Fisheries and Aquatic Sciences
• /
• v.26 no.9
• /
• pp.569-581
• /
• 2023

The morphology and genetic identification of Rasbora lateristriata and Rasbora argyrotaenia between cultivated and wild populations has never been reported. This study compares morphology and cytochrome c oxidase (COI) genes between farmed and wild stock Rasbora spp. in Java and Sumatra island, Indonesia. We analyzed the truss network measurement (TNM) characters of 80 fish using discriminant function analysis statistical tests. DNA was extracted from muscle tissue of 24 fish specimens, which was then followed by polymerase chain reaction, sequencing, phylogenetic analysis, fixation index analysis, and statistical analysis of haplotype networks. Basic Local Alignment Search Tool analysis validated the following species: R. lateristriata and R. argyrotaenia from farming (Jogjakarta); Rasbora agryotaenia (Purworejo), R. lateristriata (Purworejo and Malang), Rasbora dusonensis (Palembang), and Rasbora einthovenii (Riau) from natural resources. Based on TNM characters, Rasbora spp. were divided into four groups, referring to four distinct characters in the middle of the body. The phylogenetic tree is divided into five clades. The genetic distance between R. argyrotaenia (Jogjakarta) and R. lateristriata (Malang) populations (0.66) was significantly different (p < 0.05). R. lateristriata (Purworejo) has the highest nucleotide diversity (0.43). R. argyrotaenia from Jogjakarta and Purworejo shared the same haplotype. The pattern of gene flow among them results from the two populations' close geographic proximity and environmental effects. R. argyrotaenia had low genetic diversity, therefore, increasing heterozygosity in cultivated populations is necessary to avoid inbreeding. Otherwise, R. lateristriata (Purworejo) had a greater gene variety that could be used to develop breeding. In conclusion, the middle body parts are a distinguishing morphometric character of Rasbora spp., and the COI gene is more heterozygous in the wild population than in farmed fish, therefore, enrichment of genetic variation is required for sustainable Rasbora fish farming.

• Geomechanics and Engineering
• /
• v.35 no.6
• /
• pp.603-615
• /
• 2023

Population growth and urbanization prompted engineers to propose more sophisticated and efficient transportation methods, such as underground transit systems. However, due to limited urban space, it is necessary to construct these tunnels in close proximity to existing infrastructure like high-rise buildings and bridges. Battered piles have been widely used for their higher stiffness and bearing capacity compared to vertical piles, making them effective in resisting lateral loads from winds, soil pressures, and impacts. Considerable prior research has been concerned with understanding the vertical pile response to tunnel excavation. However, the three-dimensional effects of tunnelling on adjacent battered piled foundations are still not investigated. This study investigates the response of a single battered pile to tunnelling at three critical depths along the pile: near the pile shaft (S), next to the pile (T), and below the pile toe (B). An advanced hypoplastic model capable of capturing small strain stiffness is used to simulate clay behaviour. The computed results reveal that settlement and load transfer mechanisms along the battered pile, resulting from tunnelling, depend significantly on the tunnel's location relative the length of the pile. The largest settlement of the battered pile occurs in the case of T. Conversely, the greatest pile head deflection is caused by tunnelling near the pile shaft. The battered pile experiences "dragload" due to negative skin friction mobilization resulting from tunnel excavation in the case of S. The battered pile is susceptible to induced bending moments when tunnelling occurs near the pile shaft S whereas the magnitude of induced bending moment is minimal in the case of B.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.7 no.4
• /
• pp.9-20
• /
• 2012

The purpose of this research is to confirm how the determinant factors for shopping mall selection (proximity, parking facility, benefits, mutual interaction effects, physical environment, surroundings) affect attractiveness (image and appraisal) of the traditional markets and revisit intention and suggest strategic methods for revitalization of the traditional markets. Results of this research are drawn from a survey of customers who visit any of the twenty-two traditional markets in the Seoul area at least twice a week. Moreover, the theory is verified through the structural equation model analysis using the SPSS win 18.0 and AMOS 18 version statistics package. From the determinant factors of visiting traditional markets, parking facility, physical environment, and the surroundings were significant in image attractiveness; benefits, mutual interaction effects, and physical environment showed significant effects on appraisal attractiveness. Additionally, image attractiveness was not significantly influential in retention proneness while appraisal attractiveness was a key factor in deciding whether or not to revisit. Therefore, improvement in image is important but appraisal aspects like product reliability that customers can personally assess, are more essential for revitalization of traditional markets.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.11 no.2
• /
• pp.198-208
• /
• 2000

Objectives：This study was conducted to evaluate the effects of the attachment promotion program which was designed to promote attachment between autistic children and their mothers. The program was consisted of play activity centered mother-child interaction, educational activity for mothers by lecture, video-feedback session, and emotional supports. Methods：The subjects were consisted of 11 pairs of mother and child(7 for participant group：PG, 4 for non-participant group：NPG), who were 2-4 years-old autistic children. The data were collected by video-taping, behavioral observations, and analyzed by Wilcoxon Rank(Sign) Sum Test and Content Analysis. Results：The total attachment score increased from pre test to post-test of PG was significantly higher than that of NPG. The scores of attachment behaviors indicating proximity, mutuality and affect increased significantly(p<.05), while some behaviors indicating synchrony and jointattention did not. Especially the affectionate behaviors of PG demonstrated the most notable changes and they became more active, voluntary and reciprocal. After the program, the mother's nurturing behaviors of PG increased more than that of NPG, with no significant difference between two groups. The mother's behaviors to her child of PG became more child-centered, positively responsive, supportively expressive. As the attachment was promoted, there were also positive changes in the children's autistic behaviors with a great deal of individual differences. Conclusion：Our findings suggest that Mother-Child Attachment Promotion Program could be an effective early intervention model for autistic children.

• Journal of Korea Water Resources Association
• /
• v.40 no.7
• /
• pp.571-583
• /
• 2007

The effects of climatic changes owing to urbanization, geographical and topographical conditions on Penman-Monteith reference evapotranspiration, and energy and aerodynamic terms of Penman-Monteith reference evapotranspiration have been studied. In this study, 56 climatological stations including the Seoul metropolis in South Korea have been selected, and the area of study site was set at $314\;km^2$. The climatological station is centrally located In the study area with a 10 km radius. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicated that the variation of reference evapotranspiration rate is closely related to urbanization in most climatological stations. The level of change in reference evapotranspiration was higher in areas with higher urbanization rates. The change in reference evapotranspiration appears to be caused by temperature rises following heat island phenomena due to urbanization, and by the decrease in humidity, wind speed and sunshine duration due to the Increase in residential areas in urban districts. Especially, the humidity decrease causes a significant decrease in evapotranspiration rate. The study results showed that climatic change due to urbanization and proximity to the coast had the greatest effect on reference evapotranspiration.

• Journal of Environmental Health Sciences
• /
• v.48 no.6
• /
• pp.291-297
• /
• 2022

Background: PM_2.5 and black carbon (BC) can be generated from cooking and from vehicle operation. Street vendors may be exposed to PM_2.5 and BC due to their proximity both to roads and to cooking activities. Objectives: The objectives of this study were to evaluate the PM_2.5 and BC concentrations in cooking stalls and to determine the effects of cooking activity and of types of cooking. Methods: Indoor and outdoor PM_2.5 and BC concentrations, temperature, and relative humidity were measured in 32 stalls in April and May 2022. Behavioral factors such as the presence of cooking activity and types of cooking were observed. Student's T-test was performed using the difference of indoor and outdoor PM_2.5 and BC concentrations to compare the effects of cooking activity and to compare types of cooking. Results: One-hour averages of the difference in indoor and outdoor PM_2.5 concentrations for cooking stalls and non-cooking stalls were 9.7±15.7 ㎍/m³ (n=22) and -0.5±0.4 ㎍/m³ (n=10), respectively. The difference in indoor and outdoor PM_2.5 concentrations in cooking stalls was significantly higher than in non-cooking stalls (p<0.05). The indoor PM_2.5 concentration for stalls for Chinese pancakes and teokbokki exceeded the standards for indoor air quality in South Korea (50 ㎍/m³ ). The indoor PM_2.5 concentration for Korean pancake stalls exceeded the standards for outdoor air quality in South Korea (35 ㎍/m³ for 24 hours). Conclusions: The PM_2.5 concentrations in stalls with cooking activity was significantly higher than those in stalls without cooking activity. Some stalls with certain types of foods exceeded standards for indoor and outdoor air quality in South Korea. Better management of indoor air quality in stalls with cooking activities is necessary.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5B
• /
• pp.445-458
• /
• 2010

The effects of geographical and climatic factors on annual and monthly pan and Penman evaporation were analyzed. 52 climatological stations were selected and trend analyses were performed. Furthermore, cluster analysis and multiple linear regression analysis were performed to understand the effects of geographical and climatic factors on pan and Penman evaporation. Based on stepwise multiple linear regression analysis, annual pan evaporation is proved to be mainly controlled by urbanization as geographical factor, and annual pan evaporation is also controlled by temperature, relative humidity, wind speed, and solar radiation as climatic factor. Especially wind speed is considered to be most significant climatic factor which affects pan evaporation. Meanwhile, Penman evaporation is not affected by geographical factors but it is affected by climate factors such as temperature, relative humidity, wind speed, and solar radiation except precipitation. Furthermore, the study results show that only proximity to coast affects pan evaporation trend on July; however, geographical and climatic factors do not affect pan evaporation trends in annual basis and monthly basis (January, April, and October). On the other hand, Penman evaporation trends were not affected by geographical factors in annual and monthly basises.