• Geotechnical Engineering
• /
• v.7 no.3
• /
• pp.51-64
• /
• 1991

The reliable estimation of pile bearing capacity is essential for the improvement of the re- liability and the cost-effectiveness of the design. There have been numerous pile bearing capacity prediction methods proposed up to now, however, execpt for the estimation made from the result of the pile loading test, not one method is appropriate for the reliable prediction. Due to the considerable time and expenses required to carry out the pile loading test, the test has seldom been utilized. The development of Simple Pile Loading Test(SPLT) which utilizes the pile skin friction as the required reaction force to cause the pile tip settlement, provides a solution to perform more pile loading tests and consequently a more economical pile design is possible. The separate measurement of skin friction and tip resistance during the course of performing SPLT provides a better understanding of the pile behavior than the result of the conventional pile loading test where only the total resistance is measured. On the other hand, there are some points to be clarified in order to apply the test results of SPLT to practical problem. They are the direction of the applied load to mobilize the skin friction and the use of reduced sized sliding core. In this research, both the SPLT and the conventional pile loading test on 406mm diameter steel pipe pile have been performed. From the result, it would be safe to use the measured SPLT skin friction value directly in the design, since the value is somewhat lower than the value measured in the conventional test. It is further assumed that the tip resistance value of the reduced sized sliding core should properly be analysed by taking the incluonce of scale effect into consideration.

• Korean Journal of Social Welfare
• /
• v.54
• /
• pp.65-97
• /
• 2003

This study seeks the countermeasures for the successful organization of the social welfare labor union after examining social welfare workers' cognizance about a labor union and analyzing the major factors affecting their participation in a labor union. An analysis of social welfare workers' cognizance about the social welfare labor union. demonstrates that (1) most social welfare workers have positive opinions about a labor union organization and the participation in a labor union, (2) a great part of workers prefer forming a labor union and a professional organization together in relation to the organization of social welfare workers, and (3) the effective strategies for the organization of a labor union are in the order of the uplift of social welfare workers' consciousness, the constitution of the basic organizations which propel the formation of a labor union, and the preparation of policy countermeasures which attain the supports of clients and citizens. An analysis of factors affecting the participation in a labor union shows that the attitude toward the participation behavior (positive results), subjective norm (specific individuals), subjective norm (social constituent members), and perceived behavior control in the analysis model, male, lower position in officers, and lower educational attainment in democratic characteristics, and lower democratic and professional managements in officers and longer working hours in labor environmental conditions affect positively the participation in a labor union. These results suggest several assignments for the successful organization of the social welfare labor union. First the activities that make social welfare workers recognize the beneficial results bringing about by the participation in a labor union need to be carried out, second strategies that persuade the influential individuals to supports the participation in a labor union need to be developed, third activities that make the social constituent members understand the ethical, professional, and non-productive characteristics of social service works not to be confronted with the organization of a labor union should be pursued, fourth the organizational environments in which social welfare workers can freely participate in a labor union according to their intentions need to be made up, fifth the policy countermeasures which attain the support of social welfare workers, clients and citizens should be developed and carried out, and finally the basic organizations that effectively propel the formation of a labor union need to be constituted.

• Economic and Environmental Geology
• /
• v.38 no.5 s.174
• /
• pp.547-561
• /
• 2005

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a ffw previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about $28\%$ of the shallow groundwaters exceeded the Bangladesh drinking water standard, $50{\mu}g/L$, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of $SO_4^{2-}$ and $NO_3^-$, and high contents of dissolved organic carbon (DOC) and $NH_4^+$ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciatiion during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about $1\%$ of grounwaters have concentrations higher than $10{\mu}g/:L.$ However, it was revealed that $19.3\%$ of mineral waters, and $7\%$ of tube-well waters from Nonsan and Geumsan areas contained As concentrations above $10{\mu}g/:L.$. Also, percentages exceeding this value during detailed groundwater quality surveys were $36\%\;and\;22\%$ from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.