• Transactions of the Korean Society of Mechanical Engineers
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• 제16권9호
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• pp.1681-1690
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• 1992

The effects of the stress ratio and the fiber orientation(0.deg./90.deg. and .+-.45.deg.) to the load direction on the fracture behavior of the glass/epoxy plain woven composites were studied. The tests were carried out using compact tension specimens under both static and fatigue loading. The values of $k_{a}$ obtained from the energy release rate are independent of notch depth(a/w=0.2~0.6) for the 0.deg./90.deg. specimens, but decreases with an increase in a/w for the .+-.45.deg. specimens. And $k_{q}$ has higher values than $k_{ASTM}$ has been evaluated by the ASTM E399 test procedure. It is shown in the relation between fatigue crack growth rate da/dN and stress intensity factor range .DELTA.K using modified shape correction factor that da/dN decreases with a decrease in stress ratio and is lower for .+-..deg. specimens than for 0.deg./90.deg. These phenomena can be explained by the crack deflection to the load direction.n.n.

• Applied Chemistry for Engineering
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• 제28권3호
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• pp.306-312
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• 2017

Changes in the cell growth and lipid accumulation of marine microalga Dunaliella tertiolecta were investigated in response to the combination of different stress factors including the variation of iron supply as a primary stress factor and different options in light irradiation and $CO_2$ supply as a secondary stress factor. High or limited Fe conditions could act as a stress for lipid synthesis. As a secondary stress factor, non-$CO_2$ condition was good for lipid accumulation, but the overall cell growth was sacrificed significantly after a long-time cultivation. Dark condition as a secondary stress factor also favored lipid accumulation and the extent of cell density reduction at the early period in the dark was small compared to other stress conditions. The two-stage cultivation strategy was necessary to maximize lipid production because tendencies of the cell growth and lipid content were not identical under the chosen stress condition. The first stage was for preparing a high cell density under the normal growth-favoring condition and the second stage was the stress condition to induce lipid accumulation in a short time. The short-term (12 h) incubation under the 5X Fe (3.25 mg/L) and dark conditions resulted in the best lipid productivity of 1.44 g/L/d providing 2 g/L inoculum at the second stage.

• Journal of Korea Technology Innovation Society
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• 제14권4호
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• pp.736-760
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• 2011

The importance of new renewable energy is emphasized not only new growth engine but also the key solution for the exhaustion problem of fossil energy and environment problem. For the steady growth of new renewable energy industry, securing related labor force is an essential factor. In this study, the status on labor force of new renewable energy industry was identified and forecasted the labor force demand of new renewable energy in 2015 by reflecting the industrial growth outlook on the new renewable energy. For the quantitative analysis methodology, the stock approach of Bureau of Labor Statistics (BLS) of the United States was applied. Also by performing survey on the experts, the opinions of experts on supply and demand of new renewable energy labor force or worker training programs have been gathered. As a result of study, it has been analyzed that nearly 20% annual growth rate will be shown as the labor force demand in the field of new renewable energy industry increases from 14,100 people in 2010 to 33,200 people in 2015. In the survey on experts, we could find that a plan for supplying labor force must be prepared promptly in order to accomplish new renewable energy supply objectives and industrial growth objectives by our country in the future as the supply of new renewable energy labor force is currently insufficient. Also, it has been analyzed that the effort for deciding the proper new renewable energy labor force training program standard will be necessary. This study result could be used as a material of labor force training plan for the steady growth of new renewable energy industry in the future.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.1-7
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• 2015

The industry has rapidly growth and energy supply technology advanced are become main factor which to contribute of the harmonic losses. This problem is one aspect that may affect the capability of the transmission line and also to the efficiency of electricity. This paper proposes a new scheme to allocate the cost pertaining to transmission loss due to harmonics. The proposed method, called as Generalized Harmonic Distribution Factor, uses the principle of proportional sharing method to allocate the losses among the transmission users especially for industry consumers. The IEEE 14- and 30 bus test system is used to compare the proposed method with existing method. The results showed that the proposed method provided a scheme better in allocating the cost of transmission loss, which could encourage the users to minimize the losses.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.587-594
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• 2023

This study investigates the impacts of nuclear energy consumption on environmental quality from a different perspective by focusing on carbon dioxide (CO2) emissions, ecological footprint, and load capacity factor. In this context, the South Korea case, which is a leading country producing and consuming nuclear energy, is investigated by considering also economic growth, and the 1997 Asian crisis from 1977 to 2018. To this end, the study employs the autoregressive distributed lag (ARDL) approach. Different from previous literature, this study proposes a load capacity curve (LCC) and tests the LCC and environmental Kuznets curve (EKC) hypotheses simultaneously. The analysis results reveal that (i) the LCC and EKC hypotheses are valid in South Korea; (ii) nuclear energy has an improving effect on the environmental quality; (iii) renewable energy does not have a significant long-term impact on the environment; (iv) the 1997 Asian crisis had an increasing effect on the load capacity factor; (v) South Korea has not yet reached the turning point, identified as $55,411, where per capita income improves environmental quality. Overall, the results show the validity of the LCC and EKC hypotheses and prove the positive contribution of nuclear energy to South Korea's green development strategies.

• Journal of Mechanical Science and Technology
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• 제20권4호
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• pp.473-481
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• 2006

Predicting fatigue life by numerical methods was almost impossible in the field of rubber materials. One of the reasons is that there is not obvious fracture criteria caused by nonstandardization of material and excessively various way of mixing process. But, tearing energy as fracture factor can be applied to a rubber-like material regardless of different types of fillers, relative to other fracture factors and the crack growth process of rubber could be considered as the whole fatigue failure process by the existence of potential defects in industrial rubber components. This characteristic of fatigue failure could make it possible to predict the fatigue life of rubber components in theoretical way. FESEM photographs of the surface of industrial rubber components were analyzed for verifying the existence and distribution of potential defects. For the prediction of fatigue life, theoretical way of evaluating tearing energy for the general shape of test-piece was proposed. Also, algebraic expression for the prediction of fatigue life was derived from the rough cut growth rate equation and verified by comparing with experimental fatigue lives of dumbbell fatigue specimen in various loading condition.

• Nuclear Engineering and Technology
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• 제40권5호
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• pp.409-418
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• 2008

Because the interaction layers that form between U-Mo particles and the Al matrix degrade the thermal properties of U-Mo/Al dispersion fuel, an investigation was undertaken of the undesirable feedback effect between an interaction layer growth and a centerline temperature increase for dispersion fuel. The radial temperature distribution due to interaction layer growth during irradiation was calculated iteratively in relation to changes in the volume fractions, the thermal conductivities of the constituents, and the oxide thickness with the burnup. The interaction layer growth, which is estimated on the basis of the temperature calculations, showed a reasonable agreement with the post-irradiation examination results of the U-Mo/Al dispersion fuel rods irradiated at the HANARO reactor. The U-Mo particle size was found to be a dominant factor that determined the fuel temperature during irradiation. Dispersion fuel with larger U-Mo particles revealed lower levels of both the interaction layer formation and the fuel temperature increase. The results confirm that the use of large U-Mo particles appears to be an effective way of mitigating the thermal degradation of U-Mo/Al dispersion fuel.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.572-582
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• 2021

This study investigated the creep and creep crack growth (CCG) behavior of the base metal (BM), weld metal (WM), and heat affected zone (HAZ) in a Gr. 91 weldment, which was made by a shield metal arc weld process. A series of tensile, creep, and CCG tests were performed for the BM, WM, and HAZ at 550 ℃. Creep behavior of the BM, WM, and HAZ was analyzed in terms of various creep laws; Norton's power-law, Monkman-Grant relation and damage tolerance factor (λ), and their constants were determined. In addition, each CCGR law for the BM, WM, and HAZ was proposed and compared in terms of a C^*-fracture parameter. The WM and HAZ revealed faster creep rate, lower rupture ductility, and faster CCGRs than the BM, but they showed a similar behavior in the creep and CCG. The CCGRs obtained in the present study exhibited a marginal difference when compared with those of RCC-MRx of currently elevated design code in France. A creep crack path in the HAZ plane progressed towards a weak fine-grained HAZ adjacent to the BM.

• Proceedings of the KIEE Conference
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1088-1090
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• 1993

This paper shows efficient peak demand control method in office buildings. With a rapid growth of national economics and living standard, electrical energy consumption markedly increased. Expecially, it is increased electrical energy comsumption in the office buildings and thus an energy conservation through efficient use of electricity became more important. From the data of electric equipment capacity and electric power consumption for 96 buildings, current levels of demand factor and a growth trend of peak loads by office buildings were surveyed and analyzed. In addition the efficient peak demand control method in office buildings were studied.

• Journal of Animal Science and Technology
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• 제62권3호
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• pp.334-347
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• 2020

The adequate intake of energy and lysine for primiparous sows are necessary for maternal growth of sows and growth of their progeny. This study was conducted to evaluate the effects of dietary energy and lysine levels on primiparous sows and their progeny. A total of 48 gilts (Yorkshire × Landrace), with an initial body weight (BW) of 168.1 ± 9.71 kg and at day 35 of gestation, were allotted to eight treatment groups with a 2 × 4 factorial arrangement. The first factor was metabolizable energy levels in diet (3,265 or 3,365 kcal of ME/kg), and the second factor was lysine levels in diet (gestation 0.55%, 0.65%, 0.75%, 0.85%, lactation 0.70%, 0.85%, 1.00%, 1.15%). The BW gain (p = 0.07) and backfat thickness (p = 0.09) in the gestation period showed a tendency to be increased in sows fed the high-energy diets. In the lactation period, sows fed the high-energy diets tended to be greater BW (p = 0.09) and less BW loss (p = 0.05) than those of sows fed the low-energy diets. Sows fed high-energy diets had a tendency of greater piglet weight at day 21 of lactation and greater piglet weight gain (p = 0.08 and p = 0.08, respectively). Although the blood urea nitrogen (BUN) was increased linearly as dietary lysine level increased at day 110 of gestation (Linear, p = 0.03), the BUN was decreased linearly as dietary lysine level increase at day 21 of lactation (Linear, p < 0.01). In the composition of colostrum, sows fed high-energy diets had greater casein, protein, total solid, solid not fat, and free fatty acid concentrations than those of sows fed low-energy diets (p < 0.05). Supplementation of total lysine 0.75% for gestation and 1.00% for lactation with 3,365 kcal of ME/kg energy level could be applied to the primiparous sows' diet to improve performance of sows and growth of their progeny.