• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.86-93
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• 2023

A bridge health monitoring technology is under development for the safety management of aged bridges. The bridge health monitoring technology has been developed mainly for single bridge management at a large scale, so it uses wire-based systems for power supply and data transfer. However, the wire-based systems need to be improved for the sporadically distributed small-sized bridges on local roads. This study proposed a wireless structural health monitoring system for small-sized bridges. The proposed monitoring system overcomes the limitations of wired systems by providing wireless power through solar power and utilizing LTE technology to transmit measurement data. In addition, a remote control system and power management plan were proposed to ensure the stability of the bridge measurement system. The proposed measurement system was installed on 32 bridges on fields and verified the operability by collecting 80.6% of measurement data for one year. The proposed system can support the health monitoring of aged bridges on local roads.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.1
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• pp.90-94
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• 2023

Carbon fiber(CF) with excellent thermal conductivity and electrical conductivity is attracting attention as an alternative material because metal heating elements have problems such as high heat loss and fire risk. However, since CF is oxidized and disconnected at about 200℃ or higher, the application of heating elements is limited, and CF heating elements in the form of vacuum tubes are currently used in some commercial heaters. In this work, polyimide(PI) with high heat resistance was coated on the surface of carbon fiber by electrophoretic deposition to prevent oxidation of CF in the atmosphere without using a vacuum tube, and the coating thickness and heat resistance were investigated according to the applied voltage. The heater made by connecting the PI-coated CF heating elements in series showed stable heating characteristics up to 292℃, which was similar to the heating temperature result of the heat transfer simulation. The PI layer coated by the electrophoretic deposition method is effective in preventing oxidation of CF at 200℃ or higher and is expected to be applicable to various heating components such as secondary batteries, aerospace, and electric vehicles that require heat stability.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.54-69
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• 2022

We conducted a field survey from 2018 to 2020 to analyze the spatial distribution of phytoplankton communities at 13 stations in the East Sea. The diatom Chaetoceros curvisetus appeared as the dominant species in winter, and small flagellates less than 20 ㎛ prevailed in all seasons except winter. The seasonal average range of the micro (>20 ㎛), nano (20 ㎛≥Chl-a>3 ㎛), and picophytoplankton (≤3 ㎛) was 20.6-26.2%, 27.1-35.9%, and 40.8-49.0%, respectively. The composition ratio of nano and picophytoplankton was high at the surface mixed layer from spring to autumn when the water columns were strongly stratified. Especially, the stability of the water mass was increased when the summer surface water temperature was higher than that of the previous year. As a result, the nutrient inflow from the lower layer to the surface was reduced as the ocean stratification layer was strengthened. Therefore, the composition ratio of nano and picophytoplankton was the highest at 77.9% at the surface mixed layer. In conclusion, the structure of the phytoplankton community in the East Sea has been miniaturized, which is expected to form a complex microbial food web structure and lower the carbon transfer rate to the upper consumer stage.

• Journal of Practical Agriculture & Fisheries Research
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• v.19 no.1
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• pp.139-151
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• 2017

This study was conducted to confirm the rumen fermentation characteristics of large-scale CoenzymeQ10(CoQ10) producing bacteria R. spharoides in rumen. We conducted in vitro continuous culture test to investigate the characteristics of rumen fermentation with 5% R. spharoides as a direct fed microorganism. A rumen microbial fermentation characteristic has stability at after 12 days for 15 day of experimental period. pH value, NH₃-N, microbial protein synthesis, ADF digestibility and NDF digestibility were not shown significantly differences between control and treatment. However, UDP was significantly higher in treatment than control (p<0.05). CoQ10 concentration was 336.0mg/l with 5% R. spharoides. On the other hands, CoQ10 was not detected without R. spharoides. Our study was shown that R. spharoides can produce CoQ10 in rumen environment without harmful effects on rumen fermentation parameter. CoQ10 in rumen may transfer into cow milk through cow metabolism. This strategy might be helpful for producing functional dairy cow milk.

• Journal of Consumption Culture
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• v.15 no.1
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• pp.93-118
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• 2012

The purpose of this study was to examine the effect of a householder's working type on household saving from the perspective of precautionary saving behavior theory and the determinants of household saving by householder's working type. The data for this study was from the 2009 year of the Korea Welfare Panel Survey (KOWEPS), consisting of 2,463 households with householders whose working type was regular or non-regular employment(temporary, daily or public work). OLS regression analyses and Chow-tests were performed. In the regression analyses, the dependent variables for household saving were precautionary saving and precautionary asset. Precautionary saving was operationalized with the amount of average monthly saving and the ratio of average monthly saving to average monthly disposable income, and precautionary asset was operationalized with the amount of financial assets and the ratio of financial assets to net assets. The independent variables were household income, household assets, householder's working type(regular, non-regular), householder's age, sex, education level and marriage status, income level, the number of household members, housing type, debt, and public transfer income. Monthly average total consumption expenditures for household income, and net assets for household assets, the existence of spouse for marriage status, poverty for income level were used. Public transfer income was classified into three, social insurance, basic assistance and government assistance. For the analyses, Stata 11.0 version was used. The results are as follows: Householder's working type was significantly related to the precautionary saving behavior of a household. However, the precautionary saving and the precautionary asset of a household with a householder in non-regular working type was lower than those of a household with a householder in regular working type. This result is not consistent with the expectation from the perspective of precautionary saving behavior that the saving of a household with a householder in non-regular working type is expected to be higher than that of a household with a householder in regular working type. According to the analyses of the determinants for precautionary saving behavior by householder's working type, monthly average total consumption expenditures, debt, net assets, poverty, the number of household members, basic assistance were statistically significant variables. The positive relation of basic assistance to precautionary saving(the amount of average monthly saving and the ratio of average monthly saving)is a noteworthy result in the analyses of the determinants for household saving by householder's working type. The above results suggest the followings. First, it is easy to predict the unstability of economic life of a household with a householder in non-regular working type because of relatively low precautionary saving and precautionary asset. The reason for the low precautionary saving and the low precautionary asset may be a low current income of the household in spite of its willingness to save. If this reasoning is possible, it suggests that policies are needed for households with householders in non-regular working type to save. Second, the relatively low precautionary saving and precautionary asset of a household with a householder in non-regular working type suggest also their long-term economic stability. This suggests they need to try a long-term financial planning even though they have limitations to save for future because of their low current income. It is necessary to develop the financial planning for the households with unstable incomes. Third, the determinants for precautionary saving behavior by householder's working type were mostly the ones which reflect the economic condition of a household. This suggests that the economic condition of a household is a core factor for household saving. Consequently, it emphasizes the efforts for a household to acquire the adequate level of income for saving. Forth, the positive relation of basic assistance to precautionary saving(the amount of average monthly saving and the ratio of average monthly saving) suggests the possibility for a household to accumulate the precautionary saving and the precautionary asset in the channel of basic assistance.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.55-64
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• 1989

Reduction and equilibrium of vanadium-DTPA (DTPA = diethylenetriaminepentaacetic acid, $H_5A$) complexes at mercury electrodes are studied in 0.5M $NaClO_4$ aqueous solution at 3.2 < pH < 10.5 and 25$^{\circ}$C. At 3.2 < pH < 5.9, the reduction reaction is $V{\cdot}A^{2-}+H^-+e^-=V{\cdot}HA^{2-}$, while at 5.9 < pH < 10.5 it is $V{\cdot}A^{2-}+H^-+e^-=V{\cdot}A^{3-}$. The stability constants of $V{\cdot}HA^{2-}$ and $V{\cdot}A^{3-}$ are found to be $6.46{\times}10^{9}$ and $3.09{\times}10^{14}$, respectively. V(IV)-DTPA undergoes stepwise complexation as $VO^{2+}+H_2A^{3-}=VO{\cdot}HA^{2+}H^{+}$ and $VO{\cdot}HA^{2-}=VO{\cdot}A^{3+}+H$, where acidity constant of $VO{\cdot}HA^{2-}$- is pKa = 7.15. Stability constants of $VO{\cdot}HA^{2-}$ and $VO{\cdot}A^{3-}$ are found to be $1.41{\times}10^{14}$ and $3.80{\times}10^{17}$, respectively. It is detected that $VO^{2+}-DATA$ is reduced irreversibly to $VO^{2-}$ with the transfer coefficient of $\alpha$ = 0.43. At more cathodic overpotential, the reduction is stepwise as V(IV)${\to}$V(III)${\to}$V(II). The first one corresponds to $VO{\cdot}HA^{2-}+e^{-}{\to}VO{\cdot}HA{3+}$ at 3.2 < pH < 7.2 and $VO{\cdot}A^{3-}+e^{-}{\to}VO{\cdot}A^{4-}$ at 7.2 < pH < 10.5. The second is identical to that of V(III). Diffusion coefficients of $VO{\cdot}HA^{2-}$ and $VO{\cdot}A^{3-}$ are found to be $(9.0{\pm}0.3){\times}10^{-6}cm^2/s$ and $(5.9{\pm}0.4){\times}10^{-6}cm^2/ses$, respectively.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.331-343
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• 2017

In this study to improve stability, workability and economics of the H-Pile+Earth plate or H-Pile+Earth plate+Cutoff grouting currently in use, we had developed HCS method belonging to the retaining wall which is consisting of a combination H-Pile, Plastic Sheet Pile and Steel Square Pipe for gap maintenance and reinforcement of flexible plastic Sheet Pile, and the behavior of each member composing HCS method is investigated by three-dimensional finite element analysis. To numerically analyze the behavior of the HCS method, we have performed extensive three-dimentional finite element analysis for three kinds of plastic Sheet Pile size, two kinds of H-Pile size and three kinds of H-Pile installation interval, one kinds of Steel Square Pipe and three kinds of Steel Square Pipe installation interval. After analyzing the numerical results, we found that the combinations of $P.S.P-460{\times}131.5{\times}7t$ (PS7) and H-Pile $250{\times}250{\times}9{\times}14$ (H250), $P.S.P473{\times}133.5{\times}9t$ (PS9) and H-Pile $300{\times}200{\times}9{\times}14$ (H300) is the most economical because these combinations are considered to have a stress ratio (=applied stress/allowable stress) close to that as the stiffness of H-Pile, plastic Sheet Pile and Steel Square Pipe composite increased, the horizontal displacement of the retaining wall and the vertical displacement of the upper ground decreased. Especially, due to the arching effects caused by the difference in stiffness between H-Pile and plastic Sheet Pile, a large part of the earth pressure acting on plastic Sheet Pile caused a stress transfer to H-Pile, and the stress and displacement of plastic Sheet Pile were small. Through this study, we can confirm the behavior of each member constituting the HCS method, and based on the confirmed results of this study, it can be used to apply HCS method in reasonable, stable and economical way in the future.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.71-84
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• 2003

The metallic shell of soil-steel structures are so weak in bending moment that it should sustain the applied load by the interaction of the backfill soil around the structures. The shell can be subjected to excessive bending moment during side backfilling or under live-load when the soil cover is less than the minimum value. The current design code specifies the allowable deformation and Duncan(1979) and McGrath et al.(2001) suggested the strength analysis methods to limit the moments by the plastic capacity of the shell. However, the allowable deformation is an empirically determined value and the strength analysis methods are based on the results of FE analysis, hence the experimental verification is necessary. In this study, the full-scale tests were conducted on the high-profile arch to investigate its behaviors during backfilling and under static live-loads. Based on the measurements, the allowable deformation of the tested structure could be estimated to be 1.45% of rise, which is smaller than the specified allowable deformation. The comparison between the measurements and the results of two strength analyses indicate that Duncan underestimates the earth-load moment and overestimates the live-load moment, while McGrath et al. predicts both values close to the actual values. However, as the predicted factors of safeties using two methods coincide with the actual factor of safety, it can be concluded that both methods can predict the structural stability under live-loads adequately when the cover is less than the minimum.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.8
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• pp.89-121
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• 1997

Many of the measures and policies advocated by supply-siders, such as lower taxation, less government intervention, more freedom from restrictive legislation and regulation, and the need for increased productivity can be found in writing the classical economist. Nor is supply-side economics a complete divorcement from Keynesian analysis. In both camps the objectives are the same-high level employment, stable prices and healthy economic growth, the means or suggestions for attaining the objectives, however, differ. Consequently, recommended economic policies and measures are different. keynesians rely primarily on the manipulation of effective demand to increase output and employment and to combat inflation. They assume ample resources to be available in order that supply will respond to demand. The supply-siders emphasize the need to increase savings, investment, productivity and output as a means of increasing income. Supply-siders assume that the increase in income will lead to an increase in effective demand. Keynesians suggest that savings, particularly those not invested, dampen economic activity. Supply-siders hold that savings, or at least an increase in after-tax income, stimulates work effort and provides funds for investment. Perhaps keynesians are guilty of assuming that most savings are not going to be invested, whereas supply-siders may erroneously assume that almost all savings will flow into investment and/ or stimulate work effort. In reality, a middle ground is possible. The supply-siders stress the need to increase supply, but Keynes did not preclude the possibility of increasing economic activity by working through the supply side. According to Keynes' aggregate demand-aggregate supply framework, a decrease in supply will increase output and employment. It must be remembered, however, that Keynes' aggregate supply is really a price. Lowering the price or cost of supply would there by result in higher profit and/ or higher output. This coincides with the viewpoint of supply-siders who want to lower the cost of production via various means for the purpose of increasing supply. Then, too, some of the means, such as tax cuts, tax credits and accelerated depreciation, recommended by suply-siders to increase productivity and output would be favored by Keynesians also as a means of increasing investment, curbing costs, and increasing effective demand. In fact, these very measures were used in the early 1960s in the United State during the years when nagging unemployment was plaguing the economy. Keynesians disagree with the supply-siders' proposals to reduce transfer payments and slow down the process of income redistribution, except in full employment inflationary periods. Keynesians likewise disagree with tax measures that favored business as opposed to individuals and the notion of shifting the base of personal taxation away from income and toward spending. A frequent criticism levied at supply-side economics is that it lacks adequate models and thus far has not been quantified to any great extent. But, it should be remembered that Keynesian economics originally was lacking in models and based on a number of unproved assumptions, such as, the stability of the consumption function with its declining marginal propensity to consume. Just as the economic catastrophe of the great depression of the 1930s paved the way for the application of Keynesian or demand-side policies, perhaps the frustrating and restless conditions of the 1970s and 1980s is an open invitation for the application of supply-side policies. If so, the 1980s and 1990s may prove to be the testing era for the supply-side theories. By the end of 1990s we should have better supply-side models and know much more about the effectiveness of supply-side policies. By that time, also, supply-side thinking may be more crystallized and we will learn whether it is something temporary that will fade away, be widely accepted as the new economics replacing Keynesian demand analysis, or something to be continued but melded or fused with demand management.

• Korean Journal of Poultry Science
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• v.41 no.2
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• pp.135-142
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• 2014

This study was conducted to evaluate dietary effects of Marigold extract on laying performance, egg quality, oxidative stability of egg yolk and lutein transfer into chicken eggs. A total of one-hundred eighty nine 55-wk-old Hy-Line Brown layers were divided into seven groups and fed control diet or each experimental diet containing 0.1, 0.3, 0.5, 1.0, 1.5 or 2.0% Marigold extract. Egg production, egg weight and daily egg mass were not affected by dietary treatments. The yolk colors in groups fed diets containing Marigold extract were significantly higher than that of control. The Haugh unit were tended to be improved by feeding of diets containing Marigold extract although there were no significant difference in egg shell strength and thickness. The MDA (malondialdehyde) contents in groups fed diets containing Marigold extract above 0.5% were significantly reduced than that of control. After 14d of storage, the Haugh unit values in groups feed diets containing 0.3 and 1.0% Marigold extract were significantly higher than that of control (p<0.05). The concentration of lutein in egg yolk increased by feeding of Marigold extract. When 2% Marigold extract was supplemented to the diet, lutein content of egg was increased as much as 1.71 mg/60 g. These results indicated that the use of Marigold extract in layer diets was effective in egg quality and for the production of lutein fortified eggs.