• Journal of Korean Society of Steel Construction
• /
• 제26권1호
• /
• pp.43-53
• /
• 2014

A single plate connection(SPC) consists of a plate welded to the columns and bolts connected to the beam web. The SPC is widely used for a simple shear connection of steel structure because it is easy-to-fabricated, easy-to-installed and economical. The conventional SPC is used for 2 to 12 bolts in a single vertical row. It is designed to limit the plate thickness by bolt diameter to obtain flexible and ductile connections. The design strength for eccentric shear shall be the lesser of the shear strength of bolts or bearing strength of plate and when the design strength is decided by edge distance failure, the results can be very conservative. Although the research on special solution for 'weak-plate/strong-bolt' model with 2 to 4 bolts has been conducted by L. S. Muir, and W. A. Thonton, 2004, study on generalized design procedures did not conduct. This study proposed design procedure for evaluation of the design strength of eccentric shear bolt groups on a single plate connection based on the actual edge distance and the direction of bolt reaction forces by using elastic vector method(EVM) and instantaneous center of rotation method(ICM).

• Journal of the Mineralogical Society of Korea
• /
• 제18권1호
• /
• pp.1-9
• /
• 2005

The electrocatalytic reduction of O₂ was investigated with methyl viologen and methylene blue incorporated clay-modified electrodes. Clay suspensions were prepared with Na-montmorillonite, Ca-montmorillonite, and kaolinite. The methyl viologen-clay modified electrodes were made by coating clay suspensions adsorbing methyl viologen on a glassy carbon electrode. Cyclic voltammetry were performed in aqueous media to investigate the electrocatalytic property of the modified electrode in reducing O₂. A Na-montmorillonite modified electrode showed the greatest adsorption capacity for methyl viologen. The modified electrode made of Na-montmorillonite suspension of 0.87 g/10 mL and a 2.5 mM of methyl viologen solution showed the most effective electrocatalytic property, where the catalytic reduction potential was shifted by 242.6 mV toward the positive potential. The electrocatalytic ability was more significant in acidic (pH=3.7) and alkaline (pH=12.7) media than the neutral pH range (6.3∼8.3). The methyl viologen-Na-montmorillonite modified electrode had the good reproducibility and maintain the electrocatalytic property over 20 times reuse.

• Journal of the Korean Geotechnical Society
• /
• 제33권2호
• /
• pp.17-26
• /
• 2017

Pile foundations that support offshore structures or transmission towers are dominantly subjected to cyclic lateral loads due to wind and waves, causing permanent displacement which can severely affect stability of the structures. In this study, a series of cyclic lateral load tests were conducted on a pre-installed aluminum flexible pile in sandy soil with three different relative densities (40%, 70% and 90%) in order to evaluate the permanent displacement of a cyclic laterally loaded pile. Test results showed that the cyclic lateral loads accumulated the irreversible lateral displacement, so-called permanent displacement. As the number of cyclic lateral load increased, accumulated permanent displacement increased, but the permanent displacement due to one loading cycle gradually decreased. In addition, the permanent displacement of a pile increased with decrement of relative density and decreased by soil saturation. From the test results, the normalized permanent displacement defined as the cumulative permanent displacement to the initial permanent displacement ratio was investigated, and empirical equations for predicting the normalized permanent displacement was developed in terms of relative density of the soil and the number of cyclic lateral load.

• Journal of the Korean GEO-environmental Society
• /
• 제15권2호
• /
• pp.5-15
• /
• 2014

Target reliability index in the limit state design indicated the safety margin and it is important to determine the partial factor. To determine the target reliability index which is needed in the limit state design, the six design and construction case histories of gravel compaction piles (GCP) were investigated. The limit state functions were defined by bulging failure for the major failure mode of GCP. The reliability analysis were performed using the first order reliability method (FORM) and the reliability index was calculated for each ultimate bearing capacity formulation. The reliability index of GCP tended to be penportional to the safety factor of allowable stress design and average value was ${\beta}$=2.30. Reliability level that was assessed by reliability analysis and target reliability index for existing structure foundations were compared and analyzed. As a result, The GCP was required a relatively low level of safety compared with deep and shallow foundations and the currd t reliability level were similar to the target reliability in the reinforced earth retaining-wall and soil-nailing. Therefore the target reliability index of GCP suggested as ${\beta}_T$=2.33 by various literatures together with the computed reliability level in this study.

• Korean Journal of Legislative Studies
• /
• 제23권1호
• /
• pp.113-149
• /
• 2017

This study aims to identify the micro-level, social psychological foundation of regionalism and analyze its change and continuity by comparing 1988, 2003, and 2016 survey results. Drawing on the theory of prejudice and social identity, it clarifies the concept of regionalism and examines its affective, behavioral, cognitive implications. In the empirical analysis, where it takes advantage of relevant questions of the same or similar wording in three nationally representative surveys, the study identifies the changes in regionalism at the individual level focusing on anti-Honam prejudice and discrimination and attribution of regional conflict. First, anti-Honam prejudice has been in decline nationally as well as regardless of where one has grown up, except for Daegu/Kyungpook area. Second, anti-Honam prejudice has been weakened among younger generations while regional party identification now affects the sentiment in the direction of regional cleavage overlapped with ideological leanings. Third, while most respondents do not experience explicit discrimination, Honam natives are still more likely to experience discrimination, especially identity and self-esteem related, due to his or her home town. Fourth, Honam natives have been more likely to attribute regional conflict to an external, structural factor like government economic policy and less likely to a subjective one like regional sentiment, which seems to be consistent with attributional attitudes of the victims of prejudice. The study ends with the discussion of how to reduce further anti-Honam prejudice, which includes contact hypothesis, recategorization, cross-categorization, and de-categorization.

• Korean Journal of Social Welfare Studies
• /
• 제40권3호
• /
• pp.41-68
• /
• 2009

Grandparent-grandchildren family adolescents(GGFAs) need to be well discussed because they tend to be more influenced by the negative surroundings than ordinary family adolescents. Over the past few years, several studies have been made on the correlation between the risk factor, the protective factor and the school resilience of GGFAs, but these studies have the limit to explain the only correlation between the one factor and the school resilience. So the purpose of this study was to examine not only the direct effect between the risk factor and the protective factor, but also the parametric path and effect that the one factor has influence on the correlation between the another factor and the school resilience of GGFAs. We investigated the 328 GGFAs in Korea, and the analytic method used was the Structural Equation Modeling(SEM). The followings are the results of this paper. It was found that the model adaptability had a considerable validity by inspecting the SEM, which showed not only the direct effect between the risk factor, protective factor and the school resilience of GGFAs, but also the mediation effect by the protective factor. The risk factors - the indifference of teacher, the negative attachment relationship, melancholy, uneasiness etc - had a negative influence on the school resilience of GGFAs. The protective factors - the supporss etteacher, self-esteem etc - had a positive influence on the school resilience of GGFAs. The protective factors were found to reduce the negative influence on the school resilience of GGFAs.

• Journal of the Korean GEO-environmental Society
• /
• 제22권11호
• /
• pp.5-13
• /
• 2021

The interest of expecting the liquefaction damage is increasing due to the liquefaction in Pohang in 2017. Liquefaction is defined as a phenomenon that the ground can not support the superstructure due to loss of the strength of the ground. As an alternative against this, many studies are being conducted to increase the precision and to compose a liquefaction hazard map for the purpose of identifying the scale of liquefaction damage using the liquefaction potential index (LPI). In this research, in order to analyze the degree of precision with regard to spatial interpolation objects such as LPI value and geotechnical information for LPI determination, liquefaction hazard map were made for the target area. Furthermore, based on the trend of precision, probability value was analyzed using probability maps prepared through qualitative characteristics. Based on the analysis results, the precision of the liquefaction hazard map setting the spatial interpolation object as geotechnical information is higher than that as LPI value. Furthermore, the precision of the liquefaction hazard map does not affect the distribution of the probability value.

• Journal of the Korean Geotechnical Society
• /
• 제37권7호
• /
• pp.13-23
• /
• 2021

If roads, bridges, buildings, etc. are built on the ground with soft clay or organic soil, there may be a lot of problems in geotechnical engineering such as settlement and stability due to the large settlement and lack of bearing capacity. In extreme cases, it may appear due to shear failure or collapse of the constructed structure, so a ground improvement method is indispensable to increase the strength of the ground and to suppress settlement. In this study, the settlement according to each groundwater level condition was analyzed using the measurement results for the groundwater level conditions, one of the important factors in predicting the settlement in dredged and reclaimed ground, and the groundwater level conditions applied to the settlement analysis were proposed by comparing it with settlement generated 5 years after construction. As a result of the analysis, it is judged that it is reasonable to apply the measured groundwater level during construction and the low water ordinary neap tide (L.W.O.N.T) during load application for the groundwater level in the settlement analysis. In addition, in the case of the dredged and reclaimed ground, it is estimated that the water pressure acting on the clay layer is nonlinear, as the result of the observations of the head of water at the observation points above and below the in-situ clay layer were different.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제20권6호
• /
• pp.228-238
• /
• 2019

The purpose of this study is to investigate the relationship between transaction justice and customer performance. In this study, data were gathered from questionnaires from customers and suppliers of manufacturing outsourcing service, and reliability, validity, and confirmatory factor analysis (CFA) were conducted and the hypothesis was verified through the structural equation modeling (SEM) analysis. The results of this study are as follows: 1)Transaction justice has a significant positive effect on customer's business performance. Distribution and Interactional justice have a small effect on business performance, but Procedural justice has a significant positive effect. 2)Transaction justice has a positive effect on partnerships. 3)The partnership between the customer and the supplier has a positive effect on the customer's business performance. 4)Partnership has positive effect on customer's management performance through mediating justice. This study is based on the fact that justice acts as a independent variable in the transactional relationship between the customer and the supplier in the manufacturing outsourcing and this is the first case that empirically investigated the effect of the justice on the customer's management performance. In order to effectively cope with a rapidly changing business environment and effectively improve management performance, it is necessary to make efforts to improve justice, especially procedural justice, by utilizing outsourcing effectively in a global competition. In this respect, this study provides important implications for the both academically and practically.

• Journal of the Korean Geotechnical Society
• /
• 제34권11호
• /
• pp.81-92
• /
• 2018

For a marine bridge foundation construction, a large-circular-steel-pipe has been proposed for supporting vertical load and preventing water infiltration. However, a ship collision can adversely affect the structural stability. This paper presents a fundamental study on dynamic responses of the large-circular-steel-pipe by an impact load. In laboratory experiments, small-scaled steel pipe is installed in a soil tank. The soil height and water level are set to 23 cm and 25~70 cm, respectively. The upper part of the steel pipe is impacted using a hammer to simulate the ship collision. The dynamic responses are measured using accelerometers and strain gauges. Experimental results show that the strain decreases as the measured location is lowered. The higher frequency components appear in the impact load condition compared to the microtremor condition. However, the higher frequency components measured at the strain gauge located below the water level do not appear. For the accelerometer signal, the maximum frequency under the impact load is higher than that of the microtremor. The maximum frequency decreases as water level increases but it is larger than the maximum frequency of the microtremor. This study shows that strain gauge and accelerometer can be useful for evaluating the dynamic responses of large-circular-steel-pipes.