• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.06a
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• pp.43-49
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• 1998

Retardation effect of heavy metals in soils caused by adsorption onto the surfaces of solids particles is well known phenomena. The adsorption of metal ions has been recognized more strong in clay mineral and organic matter contents rather than sands and gravels. In this study, we investigated the retardation effect in two sandy soils by conducting batch and column tests. The column tests were conducted to obtain the relationship between concentration and time known as breakthrough curve (BTC). We applied pulse type injection of ZnCl$_2$solution on the inlet boundary and monitored the effluent concentration at the exit boundary under steady state condition using EC-meter and ICP-AES. Batch test consisted of an equilibrium procedure for fine fractions collected from two sandy soils for various initial ZnCl$_2$concentrations, and analysis of Zn ions in equilibrated solution using ICP-AES. The results of column test showed that i) the peak concentration of Zn analyzed by ICP was far less than that detected by EC-meter for both soils and ii) travel times for peak concentration were more less identical for two different monitoring techniques. The first result can be explained by ion exchange between Zn and other cations initially present in the soil particles since ICP analysis showed a significant amount of Ca, Mg ions in the effluent. From the second result, we found that retardation effect was not present in these soils due to strong cation exchange capacity of Zn ion over other cations since we did not apply a solution containing more adsorptive cations such as Al. The result of batch test also showed high distribution coefficients (K$_{d}$) for two soils supporting the dominant ion exchange phenomena. Based on the retardation factor obtained from the Kd, we predicted the BTC using CDE model and compared with the BTC of Zn concentration obtained from ICP The predicted BTC, however, disagreed with the monitored in terms of travel time and magnitude of the peak concentrations. The only way to describe the prominent decrease of Zn ion was to introduce decay or sink coefficient in the CDE model to account for irreversible decrease of Zn ions in liquid phase.e.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.315-327
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• 2019

Back analysis has been used to evaluate the factor of safety and circular failure plane at the landfill failure site. However, the estimated circular failure plane by back analysis is quite different from what is observed in the field. Thus, this study was conducted to estimate an actual shear failure plane inside the ground which gives a more accurate failure plane. Cone penetration test (CPT), boring test, soft X-ray image scan, density logging, and ultrasonic logging were conducted at the field and laboratory. The result of CPT showed significantly lower cone resistance, pore pressure, and undrained shear strength at a particular part. This part is a possible shear failure plane inside the ground. To validate, the soft X-ray scan images were analyzed and found the disturbed (inclined) bedding plane induced by shear activity at the estimated shear failure plane. Density and ultrasonic logging tests also found a similar result. Thus, the method in this study is possible to estimate the shear failure plane inside the ground.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.463-472
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• 2021

The purpose of this study is to find a way for social welfare organizations to actively cope with environmental changes such as the corona incident according to the work coordination theory that work performance improves when actively coping with environmental changes. In other words, the mediating effect of member agility in the relationship that participatory decision-making affects job performance was identified. The subjects of the survey were workers in welfare centers in the metropolitan area and Chungcheong area, and 310 questionnaires were analyzed, and confirmatory factor analysis, research model analysis, and mediation effect verification were conducted to verify the hypothesis. As a result of the study, participatory decision-making had a significant positive effect on member agility and job performance. In addition, it was confirmed that the partial mediation model including the path that participatory decision-making directly affects job performance and the indirect effect that is linked to job performance after first affecting the agility of members is appropriate. The study has academic significance in that it verifies the effect of participatory decision-making and agility necessary for social welfare organizations, and suggests ways to improve participatory decision-making and agility in hiring, evaluation, and education of employees in social welfare organizations. In this respect, significance can also be found in practical terms.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.25-36
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• 2022

In this study, seepage control effect of relief well was evaluated quantitatively on embankment of small fill dam and levee. Seepage analysis of dam and levee were carried out according to the permeability of fill material and foundation and to analyze behaviour characteristics of seepage. The up-lift pressure at toe of embankment was analyzed which is generated by seepage according to relief well installation condition. The relief well could reduce pore water pressure which is to cause piping or up-lift pressure at foundation ground of embankment and it does not be influenced on geometric condition such as dam height and slope incline. In case of relative low permeable ground, the pore water pressure reduction effect of relief well was decreased compare with high permeable ground but it shows pore water pressure reduction effect compare with no relief well condition. The reduction effect of relief well shows relative gap according to diameter and penetration length of relief well and the installation length of relief well is the most effective factor for seepage control.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.121-131
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• 2023

This study examines the possible problem in the rainfall-runoff analysis process using the VIC (Variable Infiltration Capacity) model caused by using the effective soil depth instead of the soil depth. The parameters of the model are determined as follows. First, parameters that can be determined using available numerical information are fixed. For parameters related to direct runoff and base runoff, the recommended values of the VIC model are applied. In the case of soil depth, four cases are considered: (1) the effective soil depth is applied as the soil depth, (2) 1.5 times of the effective soil depth is applied as the soil depth by reflecting the vertical structure of the soil layer, (3) 1.25 times of the effective soil depth, and (4) 2.0 times of the effective soil depth as alternative soil depths. This study simulates the rainfall-runoff for the period from 1983 to 2020 targeting the Chungju Dam and Soyang River Dam basins of the Han River system. As a result of the study, it is confirmed that when the effective soil depth is applied instead of the soil depth, direct runoff and baseflow have opposite effects, and direct runoff increases by more than 3% while base runoff decreases by the same scale. In addition, the most influential factor in the estimation of the effective soil depth in the Chungju Dam and Soyanggang Dam basins is found to be the proportion of rock outcrop area. The difference between the direct runoff ratio and the base runoff ratio in the two basins is conformed significantly different due to the influence of the rock outcrop area.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.263-270
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• 2024

In this study, impact factors for dehydration with KOMIR-Tube system using flocculant and dewatering tube were evaluated for mine drainage sludges. The experiments were conducted on semi-active facility sludges with water contents above 90 % using KOMIR-Tube system. The flocculant and input amount were determined from laboratory experiment and the dewatering efficiency was verified onsite experiment. The sludge characteristics were identified by instrumental analysis such as zeta potential measurement, particle size analysis, XRD, XRF and SEM-EDS. Selection of flocculants for sludge dewatering treatment need to consider not only precipitated rate but also filterated rate. Floc size has to keep at least 0.7 mm. From on-site experiments, sludge dewatering using KOMIR-Tube system suggests to carry out April and May that is low rainfall and humidity considering to climate conditions. Also, dewatering rate depends on the crystal degree of mineral that mainly makes up sludges. Particularly, goethite of the iron hydroxides has better dewatering rate than ferrihydrite. Ferrihydrite is low degree of crystallinity and uncleared or broad shaped crystal, goethite is good crystallinity with needle shaped crystal so that the effect of flocculation and dewatering showed to depend on the crystal. In results, impact factors of dewatering for mine drainage sludges are related to flocculant, climate, crystallinity and shape of iron hydroxides.

• Journal of Nutrition and Health
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• v.57 no.3
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• pp.320-335
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• 2024

Purpose: This study examined the impact of adolescents' dietary behavior on their quality of life using the nutrition quotient for adolescents (NQ-A) for some high school students in Seoul. Methods: The subjects were 176 high school students living in Seoul. The NQ-A was used to assess the dietary quality, and the quality of life was assessed by categorizing it into life satisfaction, environment, health, participation and safety, leisure activities, and emotional factors using survey questions validated through previous studies. Results: The NQ score of the survey subjects was 49.30 points. Based on the NQ scores, 7.4%, 46.6%, and 46.0% of participants were categorized as the 'high', 'medium', and 'low' groups, respectively. The total NQ score and balance, diversity, and practice factor scores were positively correlated with life satisfaction, environment, health, participation and safety, and leisure activities among the quality of life subscales. Regression analysis showed that the total NQ score was positively associated with life satisfaction, health, leisure activities, and emotions; the moderation factor was negatively associated with life satisfaction and health. The balance factor was positively associated with the environmental factor. The practice factor was positively associated with health, leisure activities, and emotions, and the environment factor was negatively associated with emotions. Conclusion: These results show that adolescents' quality of life is closely related to their diet, so it is necessary to maintain a balanced and varied food intake and desirable eating behaviors to improve adolescents' quality of life. Furthermore, adolescents' quality of life is influenced by other factors. Therefore, further research is needed to assess the quality of life, including dietary factors, as well as physical, emotional, psychological, and social development.

• Journal of Nutrition and Health
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• v.38 no.2
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• pp.180-189
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• 2005

The purposes of this study were 1) to analyze the effect of the ERP quality (system quality, information quality, service quality) on the performance (end user satisfaction, user's performance, system utilization) of business, 2) to conduct the causal-effect analysis between outcome variables (user's satisfaction, user's performance, system utilization) of ERP in the contract foodservice management company. The questionnaires were distributed to 260 end users (dietitians, foodservice management managers) in charge of managing the institutional foodservice such as the office (government agencies, factories), schools (universities, middle and high school) and hospitals which were managed by contract foodservice management company 'C' in Seoul and Kyunggi. The surveys were performed from July 26, 2004 to July 30. 2004. Two hundred and fifty (250) questionnaires were responded (response rate: 96.2%). The statistical analysis was conducted using SPSS Win (11.5). And the descriptive analysis, factor analysis, reliability test, pearson correlation, simple and multiple regression analysis were performed. The results showed that among the 3 factors (system quality, information quality, service quality), the system quality and information quality were proved to have an effect on the user's satisfaction and user's performance significantly (p < .05). The influence of ERP quality (system quality, information quality, service quality) on system utilization were testified to be statistically significant (p < .05). The user's performance were affected significantly by system utilization (p < 0.001) and end user's satisfaction (p < 0.001). As a conclusion, to improve user satisfaction, which is the ultimate performance variable of an ERP system, high quality of an ERP system is the pre-requisite. And the user satisfaction and performance of business would be higher with the better quality ERP system. When constructing ERP system for the contract foodservice management company, we should improve system utilization and user satisfaction altogether so that user's performance could be ultimately enhanced and we should make efforts to enhance the quality level of ERP. (Korean J Nutrition 38(2): 180～189, 2005)

• Journal of Korean Society of Forest Science
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• v.81 no.4
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• pp.310-319
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• 1992

Vegetational data obtained from 24 quadrats of Mt. Paekdu area were analysed by applying two multivariate methods : two-way indicator species analysis(TWIMSPAN) for classification and detrended canonical correspondence analysis(DCCA) for ordination. DCCA technique allowed to extract the ordination axes that could be related to 9 environmental factors. The dominant tree species distributed in the region between 1,700-1,950m from sea level were Betula ermanii, Larix olgensis, Abies nephrolepis, and Picea jezoensis in descending order. The dominant tree species distributed in the region between 1.300-1.500m were Abies nephrolepis, Pinus koraiensis, Larix olgensis, Betula mandshurica, and Picea jezoensis in descending order. The available phosphorus content in forest soil ranged from 7 to 1.153ppm. The distribution of the major communities showed a close relationship with elevation gradient. From high to low elevation, the communities of Alnus fruticosa var. mandshurica, Betula ermanii, Larix olgensis, Abies nephrolepis, Picea jezoensis, Pinus koraiensis, and Quercus mongolica were found in descending order. At the communities where Betula ermanii was dominant, Betula ermanii forest was distributed in the high elevation area, Betula ermanii-Larix olgensis forest in the good nutrition of organic matter and $K^+$, and Abies nephrolepis forest in the good nutrition of $Mg^{{+}{+}}$ and $Ca^{{+}{+}}$. The most dominant factor influencing community distribution was elevation.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.99-108
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• 2009

Since the preexisting evaluation methods of landslide susceptibility take somehow long time to determine the slope stability based on the field survey and laboratory analysis, there are several problems to acquire immediate evaluation results in the field. In order to overcome the previously mentioned problems and incorrect evaluation results induced by some subjective evaluation criteria and methods, this study tried to develop a method of landslide susceptibility by a quantitative and objective evaluation approach based on the field survey. Therefore, this study developed an evaluation chart for landslide susceptibility on natural terrain using the AHP analysis method to predict landslide hazards on the field sites. The AHP analysis was performed by a questionnaire to several specialists who understands mechanism and influential factors of landslide. Based on the questionnaire, weighting values of criteria and alternatives to influence landslide triggering were determined by the AHP analysis. According to the scoring results of the analysed weighting values, slope angle is the most significant factor. Permeability, water contents, porosity, lithology, and elevation have the significance to the landslide susceptibility in a descending order. Based on the assigned scores of each criterion and alternatives of the criteria, an evaluation chart for landslide susceptibility was suggested. The evaluation chart makes it possible for a geologist to evaluate landslide susceptibility with a total score summed up each alternative score.