• Korean Journal of Environment and Ecology
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• v.23 no.6
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• pp.569-576
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• 2009

Sediment and nutrient loading caused by the removal of forest cover and alteration of agricultural lands in catchments have led to the deterioration in Lake Shirarutoro. To examine the effects of deforestation and agricultural activities on water quality, I examined changes in total nitrogen (TN) and total phosphorus (TP) of lake water induced by land use change, and compared them with the various research data produced over the years. Our investigation showed that the level of TN and TP in the lake water decreased when forest cover increased but increased when farmland area increased. The concentration of TN and TP was high in Lake Shirarutoro despite that its catchment was surrounded by large forests and small farmlands. This result indicates that land uses near Lake Shirarutoro have affected the quality of the lake water. I have examined the changes of sediment yield in the lake's catchment over the last approximately 300 years. Eleven core samples were obtained from the lake sediment and analyzed to establish a chronology after using two tephra layers (Ko-c2 in 1694 and Ta-a in 1739) and a $^{137}Cs$ peak (in 1963). The average sediment yield under the natural condition during the first two periods was 8.4 tons/$km^2$/year in 1694~1739 and 8.9 tons/$km^2$/year in 1739~1963 respectively. The conversion of the Shirarutoro catchment into agricultural lands and deforestation intensified, leading to an increased sediment yield of 21.1 tons/$km^2$/year during 1963~2007.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.11-18
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• 2005

In order to accurately assess the stresses occurring in the early-age concrete, a compliance function which can consider the characteristics of early-age concrete is required. Existing compliance functions, however, have the limit that they have been deduced from the data of hardened concrete and therefore, do not take into account the fast development of material properties in early-age concrete. Furthermore, the distinction between instantaneous compliance and creep compliance is not clear in the existing experimental method. The purpose of present study is to propose a compliance function which can describe the rapid change of hardening processes in early-age concrete. To this end, a test method which can estimate the instantaneous compliance without creep effects in the early-age concrete was suggested first. Based on the suggested experimental method, tests on the instantaneous as well as creep compliance were performed using MTS automatic servo-loop test machine. The test results showed that both instantaneous and aging viscoelastic compliance, which are constants in B3 model, were functions in terms of age of concrete especially at early ages. Therefore, the modified compliance function based on B3 model was proposed to provide more realistic prediction on the behavior of early-age concrete. It is expected that the present model allows more realistic evaluation of varying stresses in concrete structures at early ages.

• Resources Recycling
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• v.15 no.1 s.69
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• pp.37-45
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• 2006

For treating a huge amount of plastic waste with the environment problem, pyrolysis of plastic waste into alternative fuel oil is one or important issue in recycling methods. This study was introduced over the trend or generation of plastic waste, in Korea pyrolysis technology in domestic and foreign countries, basic technology in pyrolysis process and new technology of pyrolysis developed in KIER (Korea Institute of Energy research). The characteristics of process developed in KIER are the continuous loading treatment or mixed plastic waste with an automatic control system, the minimization of wax production by circulation pyrolysis system in non-catalytic reactor, the reuse of gas produced and the oil recovery from sludge generated in pyrolysis plant, which have greatly the advantage economically and environmetally. The experiment result data in 300 ton/yr pilot plant showed about $81\;wt\%$ liquid yield for 3 days continuous reaction time, and also the boiling point distribution of light oil (LO) and heavy oil (HO) produced in distillation tower was a little higher than that of commercial gasoline and diesel, respectively.

• Ocean and Polar Research
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• v.38 no.3
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• pp.171-184
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• 2016

In order to assess the level of contamination and identify the priority contaminants in the Busan coast, intensive sediment sampling was conducted and persistent organic pollutants and heavy metals were analyzed. The Sediment Quality Index (SQI) was derived based on the contaminant data by comparing with Sediment Quality Guidelines (SQGs) established in Korea, Canada, and Australia/New Zealand. Toxic contaminants were found to be widely distributed across the coast. Among organic contaminants, PAHs showed the highest concentration, followed by butyltins, nonylphenols, PBDEs, DDTs, PCBs, HCHs and CHLs. Heavy metals were also abundantly detected with the highest concentration of Zn followed by Cu > Cr > Pb > Ni > As > Cd > Hg. Compared to organic contaminants, most heavy metals, except for Cu and Hg, were homogeneously distributed along the coast in a good relationship with total organic carbon of sediment particles. In general, the concentrations of organic compounds and heavy metals were highest at the inner part of harbor areas with a tendency to decline from inside areas to the outside, indicating the high loading of pollutants from harbors. A high exceedance for low-SQGs and high-SQGs was found for TBT, p'-DDT, p,p'-DDD, Cu and Zn. The SQI scores calculated from low-SQGs and high-SQGs were in the range of 18-100 and 54-100, respectively. The inner part of Busan Harbor, Dadaepo Harbor, and Gamcheon Harbor were observed as being regions of concern. Overall, TBT, Cu, and p,p'-DDT were the chemicals most frequently exceeding SQGs and influencing SQI scores.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.175-185
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• 2014

This study is to develop a fatigue scale for the private security guard for a private security guard to effectively manage fatigue were tested for validity and reliability. To achieve that, this study employed purposive sampling to draw 300 samples among private security guards working for the security firms registered in Seoul District Police Office as of 2014, and used 259 samples for final analysis. Fatigue scale was developed on the basis of the scale development methods and procedures in previous studies. For data processing, SPSSWIN 18.0 program was applied to conduct exploratory factor analysis, reliability analysis, and correlation analysis, and AMOS 18.0 program was employed to conduct confirmatory factory analysis. This study came to the following conclusion. First, the validity of the fatigue measurement tool was high. In other words, content validity was high, and construct validity was also high. The factor loading of exploratory factor analysis was .452, and the standard value of confirmatory factor analysis was .403. Therefore, the tool satisfied the basis value of fit index. The sub categories of fatigue, finally drawn from validity test, were mental fatigue, nervous system dysfunction, physical deformity, and exhaustion. Secondly, the reliability of the fatigue measurement tool was high. In other words, according to item analysis, the correlation between items and their sub categories, and between items and total score was more than .602, relatively high. And the reliability coefficient (Cronbach's ${\alpha}$) was high, or more than .658. Fatigue Scale tool will be developed by private security guards in the present study is to measure the validity and reliability verification is clearly tired of the private security guards than the tools that are used in other studies in the existing area.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.9
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• pp.667-674
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• 2014

A ship's propulsion shafting system is subjected to varying magnitudes of intermittent loadings that pose great risks such as failure. Consequently, the dynamic characteristic of a propulsion shafting system must be designed to withstand the resonance that occurs during operation. This resonance results from hydrodynamic interaction between the propeller and fluid. For ice-class vessels, this interaction takes place between the propeller and ice. Producing load- and resonance-induced stresses, the propeller-ice interaction is the primary source of excitation, making it a major focus in the design requirements of propulsion shafting systems. This paper examines the transient torsional vibration response of the propulsion shafting system of an ice-class research vessel. The propulsion train is composed of an electric motor, flexible coupling, spherical gears, and a propeller configuration. In this paper, the theoretical analysis of transient torsional vibration and propeller-ice interaction loading is first discussed, followed by an explanation of the actual transient torsional vibration measurements. Measurement data for the analysis were compared with an applied estimation factor for the propulsion shafting design torque limit, and they were evaluated using an existing international standard. Addressing the transient torsional vibration of a propulsion shafting system with an electric motor, this paper also illustrates the influence of flexible coupling stiffness design on resulting resonance. Lastly, the paper concludes with a proposal to further study the existence of negative torque on a gear train and its overall effect on propulsion shafting systems.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.289-297
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• 2013

In this study, the local buckling behavior of steel built-up columns, fabricated with grade 800MPa high performance (HSA800), was investigated to verify the suitability of width-to-thickness ratio limits adopted by the current design code. For this purpose, an experimental program was designed and performed for HSA800 steel column specimens with various width-to-thickness ratios. Then the experimental results were compared and verified with finite element analysis results. The parametric analytical studies with various width-to-thickness ratios were also performed to investigate the missing data from the limited experimental studies. From the experimental and analytical studies, It was found that the finite analysis models could reasonably estimate the test results within the 5.3% average differences. The local buckling behaviors of HSA800 steel columns were found to be largely depend on the values of initial imperfection introduced into finite element analyses.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.191-198
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• 2011

In general, conventional criticality analyses for spent fuel transport/dry storage systems have been performed based on assumption of fresh fuel concerning the potential uncertainties from number density calculation of Transuranic and Fission Products in spent fuel. However, because of economic loss due to the excessive criticality margin, recently the design of transport/dry storage systems with Burnup Credit(BUC) application has been actively developed. The uncertainties in criticality analyses on transport/storage systems with BUC technique show strong dependance upon initial enrichment and burnup rate, whereas those in the conventional criticality evaluation based on fresh fuel assumption do not show such a dependance. In this study, regulatory-required uncertainties of the criticality analyses for BK 26 Cask, which is conceptually designed spent fuel transport cask with BUC corresponding to the limiting circumstances on nuclear power plants in Korea, are evaluated as a function of initial enrichment and burnup rate. Results of this study will be used as basic data for spent fuel loading curve of BK 26 Cask.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.387-396
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• 2018

This study examined the instability factor of real income and net profits of Chung-yang Green Pepper Farm through an analysis of the operating costs. Furthermore, this paper suggests a plan for stabilizing the price by shipment adjustments resulting from an analysis of the price elasticity by A Linear Approximated Inverse Almost Ideal Demand System (LA/IAIDS). The income instability factor of the farm based on an analysis of the operating costs was attributed to the unexpected loading of utility expenses and collapse of the price due to oversupply at a specific point in time. On the other hand, this is insufficient to completely explain the income instability factor of Chung-yang Green Pepper Farm because a price collapse does not include the monthly price changes. An analysis of the price and scale flexibility of Chung-yang Green Pepper Farm by monthly data showed that annual farm net yield increases by 1.21% due to a 2.21% increase in price if the shipment quantity is reduced to 1% a year. In summary, a plan that supports the farm price received through declining shipments in winter is effective in stabilizing the income of farms. Because Chung-yang Green Pepper in Gyeongnam region has an especially high market share of 82.5%, the prices and income of Gyeongnam Chung-yang Green Pepper farms can be stabilized effectively if they form an association of producers around the Gyeongnam region and adjust the shipment.

• Journal of KIISE:Databases
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• v.35 no.3
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• pp.286-295
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• 2008

Multimedia consumer electronics(CE) devices, such as MP3 players, PMPs, and digital cameras, are electronic equipments used to record, play or create multimedia data. Most multimedia CE devices provide uses with the ability to search multimedia stored in the device and browse the search results. One of the unique requirements in multimedia CE devices is that the search results displayed in the screen must be restored quickly when the device powers off and later back on. For this purpose, the existing methods (1) re-execute the original search query, and (2) move the cursor to the original position in the search results. However, this approach may be inefficient when the number of records in the result set is large. In this paper, we propose an efficient method for multimedia CE devices that can quickly restore the search results displayed in the screen when the device powers off and later back on. The proposed method can retrieve the original search results in the screen quickly by saving and loading some information about the query evaluation plan. Though the performance evaluation, we show that the proposed method provides excellent performance regardless of the number of records in tile result set or the original cursor position.