• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.5 no.3
• /
• pp.161-175
• /
• 1985

The simplified method drawing the S-N curves in welding joints of the cover plates, the transverse stiffners and the gusset plates of the plate girders by calculation and its computer program without the direct fatigue tests, was established. And the method was applied to the Young- Dong Great Bridge, the 3 th Han River Bridge and the Kang Chon Bridge. Before this, SS 41, SS 50, SWS 50 and SWS 58 were selected, then the compact tension specimens were made by the use of these materials, the things welded by these materials transversely and the ones longitudinally to the crack propagation direction. The fatigue tests were performed by the use of these 'specimens, and the values of material constants c and m were obtained. By these results the followings were obtained. It was showed that the fatigue: strength in the case of the cover plates was much lower than in the case of other two cases. It was showed that, in the case of the cover plates with the cover plates thicker the fatigue strength was lower, but besides this the fatigue strength was not much influenced by the size of specimens. It was showed that in the difference from this the fatigue strength was sensitively influenced by the values of c and m. It was showed that in accordance with the lower values of c and m the fatigue strength was fairly higher, in accordance with the lower values of m the gradient of the S-N curves was abrupter. It was considered that if such data were accumulated continuously, in the near future the basic pattern used availably in providing the indicater of the fatigue design of the plate girders, and presuming the life-proof of the existing plate girders.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.2
• /
• pp.261-268
• /
• 2018

The study used the simplified flooding analysis model, SIMOD, to distribute the total flood discharge by time, so research on flooding in urban areas can be conducted. The conventional flooding analysis models have limitations in constructing input data and take a long time for analysis. However, SIMOD is useful because it supports rapid decision-making process using quick modeling based on simple hydrological data, such as topography and inflow flood of the study area, to analyze submerged routes formed by flooding. Therefore, the study used the SIMOD model to analyze flooding in urban areas before conducting a comparative study with the outputs from FLO-2D, which is one of the conventional flooding analysis models, to identify the model's applicability. Seongseoje was selected as the study area, as it is located downstream the Geumho river where streams flow in the adjacent areas, and dikes are high enough to apply the "Overflow and Break" scenario for urban areas. With regard to topography, the study applied DEM data for the conventional flooding analysis and DSM data to represent urban building communities, distribution of roads, etc. Input flood discharge was calculated by applying the rectangular weir equation under the bank and break scenario through a 200-year return period of a design flood level. Comparative analysis was conducted in a flooded area with a simulation time of 1-24 hours. The time for the 24-hour simulation in SIMOD was less than 7 minutes. Compared with FLO-2D, the difference in flooded areas was less than 20%. Furthermore, the study identified the need for topography data using DSM for urban areas, as the analysis result that applies DSM showed the influence of roads and buildings.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.5
• /
• pp.281-294
• /
• 2015

In order to quantitatively estimate the nonlinear destructive interaction of wave load with wind load, which is very vital for the optimal design of offshore wind energy converter, we carried out a hydraulic model test and wind tunnel test. As a substructure of offshore wind energy converter, we would deploy the monopile, which is popular due to its easiness in construction. Based on the simulation using Monte Carlo simulation using Kaimal spectrum and cross spectrum, the instantaneous maximum wind velocity is adjusted to 10 m/s. And, considering the wave conditions of the Western Sea where a pilot wind farm is planned to be constructed, $H_s=0.1m$, 0.15 m, 0.2 m is carefully chosen. It turns out that the nonlinear destructive interaction between the wind and wave loads acting on the offshore wind energy converter is more clearly visible at rough seas rather than at mild seas, which strongly support our deduction that a Large eddy, a swirling vortex developed near the bumpy water surface in the opposite direction of the wind, is the driving mechanism underlying nonlinear destructive interaction between the wind and wave loads.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.5
• /
• pp.315-323
• /
• 2015

Damage level of coastal structures has been scaled up according to increase of wave height and duration of the storm due to the abnormal global climate change. So, the design criteria for new breakwaters is being intensified and structural strengthening is also conducted for the existing breakwaters. Recently, interlocking concept has been much attention to enhance the structural stability of the conventional caisson structure designed individually to resist waves. The interlocking caisson breakwater may be survival even if unusual high wave occurs because the maximum wave force may be reduced by phase lags among the wave forces acting on each caisson. In this study, the dispersion characteristics of wave forces using interlocking system that connect the upper part of caisson with cable in the normal direction of breakwater was investigated. A simplified linear model was developed for computational efficiency, in which the foundation and connection cables were modelled as linear springs, and caisson structures were assumed to be rigid. From numerical experiments, it can be found that the higher wave forces are transmitted through the cable as the angle of incident wave is larger, and the larger the stiffness of the interlocking cable makes larger wave dispersion effect.

• Journal of Distribution Science
• /
• v.14 no.3
• /
• pp.63-71
• /
• 2016

Purpose - A variety of indicators are used for the diagnosis of economic situation. However, most indicators explain the past economic situation because of the time difference between the measurement and announcement. This study aims to argue for the resurrection of an idea: electricity demand can be used as an indicator of economic activity. In addition, this study made an endeavor to develop a new Real Business Index(RBI) which could quickly represent the real economic condition based on the sales statistics of industrial and public electricity. Research design, data, and methodology - In this study monthly sales of industrial and public electricity from 2000 to 2015 was investigated to analyze the relationship between the economic condition and the amount of electricity consumption and to develop a new Real Business Index. To formulate the Index, this study followed next three steps. First, we decided the explanatory variables, period, and collected data. Second, after calculating the monthly changes for each variable, standardization and estimating the weighted value were conducted. Third, the computation of RBI finalized the development of empirical model. The principal component analysis was used to evaluate the weighted contribution ratio among 3 sectors and 17 data. Hodrick-Prescott filter analysis was used to verify the robustness of out model. Results - The empirical results are as follows. First, compatibility of the predictability between the new RBI and the existing monthly cycle of coincident composite index was extremely high. Second, two indexes had a high correlation of 0.7156. In addition, Hodrick-Prescott filter analysis demonstrated that two indexed also had accompany relationship. Third, when the changes of two indexes were compared, they were found that the times when the highest and the lowest point happened were similar, which suggested that it is possible to use the new RBI index as a complementing indicator in a sense that the RBI can explain the economic condition almost in real time. Conclusion - A new economic index which can explain the economic condition needs to be developed well and rapidly in a sense that it is useful to determine accurately the current economic condition to establish economic policy and corporate strategy. The salse of electricity has a close relationship with economic conditions because electricity is utilized as a main resource of industrial production. Furthermore, the result of the sales of electricity can be gathered almost in real time. This study applied the econometrics model to the statistics of the sales of industrial and public electricity. In conclusion, the new RBI index was highly related with the existing monthly economic indexes. In addition, the comparison between the RBI index and other indexes demonstrated that the direction of the economic change and the times when the highest and lowest points had happened were almost the same. Therefore, this RBI index can become the supplementary indicator of the official indicators published by Korean Bank or the statistics Korea.

• Journal of Distribution Science
• /
• v.13 no.6
• /
• pp.97-104
• /
• 2015

Purpose - The distribution of agricultural products is changing due to recent shifts in environmental free trade. Specifically, the competitiveness of domestic agricultural products has weakened as a result of the Korea-China Financial Trade Agreement. Agricultural producers are faced with increasing difficulties and organized production centers are growing in importance daily. To overcome this crisis, agricultural producer organizations are vying for environment-friendly agricultural certifications, Good Agriculture Practices (GAP) and Hazard Analysis and Critical Control Point (HACCP). In particular, as consumer demand for higher safety grows, farmers are increasing their certification rates. Therefore, this certification system is expected to help strengthen the competitiveness of agricultural producer organizations. Research design/data/methodology - Organized production centers are classified by certification. A survey was conducted with 91 organizations using factor analysis and logistic regression analysis for the examination. The factor analysis results are as follows. Raw material procurement, education·specialization, marketing, joint business, organizing ability, business management, effectiveness, certification, and larger organizations were classified as the nine types of factors. These factors affect the organized production centers and are used in the logistic regression analysis. The purpose of such research and analysis is to suggest a direction for future production center policies. Results - The basic statistical results are as follows: analysis of the producer organizations of 91 sites, average number of members per site of 1,624, and average sales of 25,961 million won. Additionally, the average income per farmer is 175 million won, and the pooling system rate is 53.5%. The factor analysis results are as follows. Factor 1 consists of contract cultivation, ongoing shipment, selection subdivision, traceability, and major retailer management. Factor 2 consists of manual cultivation, specialty selection, education program, and R&D. Factor 3 consists of advertising, various dealers, various sales strategies, and a unified sales counter. Factor 4 consists of agricultural materials co-purchase, policy support, co-shipment, and incentives. Factor 5 consists of the co-selection and pooling system. Factor 6 consists of co-branding and operating by the organization's article. Factor 7 consists of the buy-sell ratio and rate of operation of the agriculture promotion center. Factor 8 consists of bargaining power in volume and participation rate of farmer certification. Factor 9 consists of increasing new subscribers. The logistic regression analysis results are as follows. Considering the results by type of certification, the environment-friendly agricultural certification type and the GAP certification type have a (+) influence. GAP and HACCP certification types affecting the education·specialization factor have a (+) influence. Considering the results for each type of certification, the environment-friendly agricultural certification types on the effectiveness factor have (-) influence; the HACCP certification types on the organizing ability and effectiveness factor have a (-) influence. Conclusions - Agricultural producer organizations should develop plans as follows: The organizations need to secure education for agricultural production; increase the pooling system ratio for sustainable organizational development; and, finally, expand the number of agricultural producer organizations.

• Journal of Distribution Science
• /
• v.11 no.10
• /
• pp.81-92
• /
• 2013

Purpose - This study empirically analyzes the effect of improvements in the quality of service management performance of college education on traders' conscious change of business management innovation and diverse sales expertise for a year. The use of traders' conscious changes and sales expertise as variables for the verification of the effects of parameters related to the active trader's traditional education market is a desirable direction. The method of research reflects the quality of education service, management result, traders' conscious changes, and sales expertise to understand the precise essence and definition of teaching quality at merchant colleges through theoretical consideration. Moreover, its impact on traders' conscious changes and sales expertise in empirical analysis acts as an intermediary. Research design, data, methodology - The hypothesis of this study leverages the SPSS statistical program. To gather actual proof, sample survey for theoretical research examined 262 valid papers of the 300 papers written by 10 merchants who graduated from merchant's university. First, using the SERVQUAL model, Parasuraman et al. (1996) indicated that for quality of education service, the configuration of factors is the same as the sympathetic performance, that is, responsiveness and empathy, and traders are aware of these elements. However, our preliminary investigation revealed that traders' university education has been excluded as a component of quality of service in the earlier studies. Moreover, we found that certainty of knowledge, reliability, and sympathy are influenced by challenges and by the changing intentions of merchant consciousness. In addition, our study confirms that improvements in convincing abilities and sales technique have a positive impact. Second, merchants' and traders' expertise are proven to affect business performance. In other words, university education of traders and merchants affects the consciousness of consumers, and changes patterns of sales. Third, the quality of service management education and change in the consciousness has a considerable impact on the trader, thereby maximizing business performance and acting as an intermediary for verification. Fourth, the quality of service management education affects the trader's sales expertise to maximize business performance. Results - To summarize, the quality of college educational services relates to the improvement of business performance and the role of the resulting virtuous cycle. Consequently, we can look for suggestions in the traditional markets, where the Government pays attention to the exterior environmental factors as well as to the changing business environment. However, the most important aspect is the merchant awareness. That is, a merchant should understand the distribution environment. Several competitor and trend analyses should be conducted to meet customers' expectations positively and proactively cope with any challenges related to changes. Further, expertise in sales and marketing skills need to be acquired to improve customer convincing abilities and develop a customer-oriented mindset. Conclusions - According to the changes in consumption trends of business enterprises, new management techniques are required to survive competition by improving traditional markets, which will necessitate more competitive education programs in merchant universities.

• Journal of Distribution Science
• /
• v.12 no.12
• /
• pp.65-73
• /
• 2014

Purpose - Distribution of agricultural products is collapsing due to recent changes in the environment balance between retailers and producers. Further, the increase in the imports of agricultural products due to free trade has caused revenue problems for producers. Agricultural producers are faced with increasing difficulties, and the organized producing center's importance is growing each day. Korean organized producing centers' policies have been conducted since 2000, and have thus been sustained for more than 10 years. Organizing a producing center's business is focused on agricultural cooperative and farming association corporation this has already have been carried out. In addition, it has achieved significant results through these organizations, but it still has many problems. Research design, data, and methodology - Organized producing centers were classified for each type. The survey covered 90 organizations, based on factor analysis, analysis of balance, and logistic regression analysis. The results of the conducted factor analysis are as follows. Production, marketing, human resources management, organizational skills, post management, safety, and scale were classified as the seven kinds of factors. These are the factors that affect the organized producing centers through the variance analysis and logistic regression analysis. The purpose of such research and analysis is to suggest the direction for the future organized producing centers' policies. Result - Results of the analysis of the variance are listed below. Items by type, production, marketing, human resource management, and organizational skills are shown to depict differences between the factors. Organization form results show that production and marketing showed a difference between the factors. The size of the organization, production, and marketing showed the difference between the factors. The factors affect organized producing centers differently depending on the type shown, as seen from the results. In contrast, the logistic regression results of the analysis are as follows. Considering the results by the type of item, and the horticulture type of marketing, human resource management has a (+) influence. Grain type and production showed a (+) influence. New types of income affecting organizational skills have a (+) influence. Considering the results for each type of organization, the agricultural cooperative type of marketing and human resource management have (+) influence. Farming association corporation type of production has a (+) influence. As a result, the size of the organization is as follows. Large organizations are production, expressed in marketing with a (+) impact. Medium-size organizations are expressed with their size factor having a (+) impact. Small organizations are expressed with a safety factor having a (+) impact. Conclusions - The types of factors display different effects. One factor is that the type of a (+) represents the influence of other factors (-) as per factor symptomatology. Therefore, the type of measures to organize a strategy to maximize the benefits of your organization should be pursued. In addition, based on the support for small organizations, improving the quality of the producer organization should be considered.

• International Journal of Highway Engineering
• /
• v.14 no.2
• /
• pp.117-129
• /
• 2012

Road safety audit is the preventive enhancement strategy for safety. : it gets rid of beforehand the potential factor of a traffic accident in the stage of road planning and design and it evaluates the appropriation for road geometric structure or safety facility to prevent traffic accident in the stage of operation after the construction. Since this strategy is introduced to our country in the early 2000s, various projects have been processed and it was legislated recently. And now, the evaluation of past project for its continuation is needed. Therefore, in this study the evaluation of road safety audit on existing freeway is performed. The spatial extent of this study is Yong-dong line on which the safety treatment was executed in 2005 and 2006. And, the temporal range of this study is each 2-year of before and after from 2005 and 2006. The empirical bayes method of observational evaluation studies is applied to analyze. As a result, there is an effect of improvement on most of treated sections. But there is ineffective or negligible on some sections. Compared with the detail of treatment on each section, the effect of multiple or various treatments is good for that section. On the other hand, the section on which effect doesn't appear is the result of single or unimportant treatments. Throughout these results, the concrete analysis can be performed and the countermeasures designed for the section on which effect doesn't appear. Also it is used as reference to the future plan and direction of road safety audit on existing freeway.

• The Journal of Engineering Geology
• /
• v.5 no.1
• /
• pp.1-20
• /
• 1995

A train overturn accident occurred on March 1993 in the Gupo area, northern part of Pusan, unfortunately had taken a heavy toll of lives and caused a great loss of property as well. The reasons for the subsidence of the basement under the railroads, which presumed to be the main cause of the accident, have been investigated from many different angles, including conventional geotechnical investigation methods. The deduced nuin reasons of the subsidence were: 1. blasting for tunnel excavation (NATM) at about 39 meter under the railroads, and 2. unexpected change of bedrock conditions along the direction of tunnel. But this accident was derived nrranlv from the lack of geological and geotechnical information under railroad area because it was impossible to drill beneath the railroads. This paper introduces a new geophysical survey techniqueseisrnic geotomography, and shows some results of the method applying to investigate the underground structure of the accident area. This method not only overcomes the unfavourable environment which many conventional investigation methods cannot face, but produces an image of underground structure with high resolution. Furthermore, the outputs from geotomogaphic analysis could provide very valuable in-situ basic parameters (like seismic velocities, elastic moduli, etc.) which is essential to the design and construction.