• International Journal of Highway Engineering
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• v.11 no.3
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• pp.23-32
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• 2009

In this paper an experimental program was launched to determine the mechanical and durability properties of spall repair materials (RCC: 3 items, PCC: 2 items, PC: 3 items). Test items were mechanical property tests such as setting times, strengths, modulus of elasticity, plastic shrinkage, and durability tests such as dynamic modulus ratio, bond property with freeze-thaw, water absorption, chemical resistance, ultraviolet exposure. Modulus of the PC products exhibits ductile while the modulus is in the order of RCC > PCC > PC. At early ages the PC products experience higher plastic shrinkage than others, henceforth stable at 28 days. Other test results such as dynamic modulus ratio, absorption, and chemical resistance show that the PCs are superior to the PCCs and the RCCs. Except for PC-2, all patch materials had bond strength more than 1.3MPa after freeze-thaw cycles of 200~300 while the PCs and the PCCs seem to be better than the RCCs. With 500 hours of ultraviolet exposure, all patch materials showed to have no crack or deterioration at the surface.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.192-200
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• 1998

This study was carried out to evaluate the effect of feeding higher protein feeds with lesser amount, but feeding the constant total protein input for all treatments, on water quality and nitrite toxicity in channel catfish ponds. There was no significant difference in survival rate among treatments $(P>0.05)$. Specific growth rate (SGR) for Treatment 1$(28\%\;protein\;and\;100\%\;of\;satiation)$ was significantly higher $(P>0.05)$ than for Treatment 3$(36\%\;protein\;and\;87.5\%\;of\;satiation)$, but not significantly higher than for Treatment 2 $(32\%\;protein\;and\;77.8\%\;of\;satiation)$ at constant digestible energy (DE), 3.08kcal/g (treatments 1, 2 and 3). At constant DE/P (treatments 4, 2 and 5), no significant difference in SGR was observed among treatments. Feed conversion ratio (FCR) slightly improved or improved as dietary protein level increased from $28\%$ to $32\%$ and feed allowance decreased by $12.5\%$, but did not improve as dietary protein level increased from $32\%$ to $36\%$ and feed allowance decreased by $22.2\%$, at constant DE and constant DE/P. There was no significant difference in water quality variables, such as total ammonia nitrogen (TAN), nitrite, chlorophyll a, soluble phosphorous concentrations among treatments, but significant difference in water quality variables over time as amount of feed fed increased $(P<0.0001)$. There was a trend toward increase in TAN and nitrite over time. A strong linear regression was observed between mean total ammonia nitrogen and nitrite for all treatments Y (Nitrite) =$0.04\times (TAN)+0.01$, $R_2=0.89$. Methemoglobin percent in the blood of catifish was not significantly different among treatments. And its mean value was $7.5\%$, which was relatively low, so that it was not serious problem in catfish production pond under these experiment conditions. There was the stronger linear regression between the percentage of Methemoglobin and the molar ratio of nitrite to chloride rather than nitrite alone: $Y\;(Methemoglobin\;\%)\;=\;58.45\;\times\;(NO^{2-}/Cl^-)\;+\;0.41,\;R^2=0.60$. These results indicate that deterioration of water quality has no strong impact on poor weight gain for $36\%$ dietary protein in this study.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.138-141
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• 2005

This study was conducted to investigate the effect of partially substituting meat meal for fish meal on the growth and body composition of juvenile olive flounder Paralichthys olivaceus during the winter season. Twenty-five fish (initial body weight, 23 g) were distributed into twelve 250 L flow-through tanks. Four experimental diets were prepared in triplicate: the control, MM20, MM40, and MM60 diets. Sixty percent mackerel meal was used as the primary protein source in the control diet. Meat meal was substituted for 20, 40, and 60$\%$ of the mackerel meal in the MM20, MM40, and MM60 diets, respectively. Survival was not significantly affected by the experimental diets. However, the weight gain and specific growth rate of fish fed the control, MM20, and MM40 diets were significantly higher than those of fish fed the MM60 diet (P<0.05). The feed efficiency ratio of fish fed the control, MM20, and MM40 diets was significantly higher than that of fish fed the MM60 diet (P<0.05). The protein efficiency ratio for fish fed the control diet was significantly higher than that for fish fed the MM40 and MM60 diets (P$\%$ substitution of meat meal for fish meal in the diet could be implemented without a reduction in growth or deterioration of the feed efficiency of juvenile olive flounder during the winter season.

• Korean Journal of Materials Research
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• v.11 no.3
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• pp.236-242
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• 2001

HfN/Si$_3$N$_4$and NbN/Si$_3$N$_4$ multilayer coatings were deposited onto a high speed tool steel substrate by reactive sputtering and their mechanical properties were evaluated in terms of the dependence of hardness and adhesion strength on the sputter deposition process parameters. The hardnesses of both HfN/Si$_3$N$_4$and NbN/Si$_3$N$_4$ multiplayer coatings increase up to the flux ratio of 0.4 but nearly do not change after that as the $N_2$/Ar flux ratio in nitride sputter deposition increases. The hardnesses of both multiplayer coatings nearly do not change with annealing at low temperatures but decrease owing to oxidation with annealing at a high temperature like 80$0^{\circ}C$ after depositing the layers by sputtering. Post-annealing at low temperatures increases the adhesion strength of the multilayers. but high temperature annealing is not desirable since it decreases the adhesion strength besides the hardness deterioration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.39-46
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• 2020

Carbonation is a deterioration which degrades structural and material performance by permitting CO₂ and corrosion of embedded steel. Service life evaluation through deterministic method is conventional, however the researches with probabilistic approach on service life considering loading and cold joint effect on carbonation have been performed very limitedly. In this study, probabilistic service life evaluation was carried out through MCS (Monte Carlo Simulation) which adopted random variables such as cover depth, CO₂ diffusion coefficient, exterior CO₂ concentration, and internal carbonatable materials. Probabilistic service life was derived by changing mean value and COV (Coefficient of variation) from 100 % to 300 % and 0.1 ~ 0.2, respectively. From the analysis, maximum reduction ratio (47.7%) and minimum reduction ratio (11.4%) of service life were obtained in cover depth and diffusion coefficient, respectively. In the loading conditions of 30~60% for compressive and tensile stress, GGBFS concrete was effective to reduce cold joint effect on carbonation. In the tensile condition, service life decreased linearly regardless of material types. Additionally service life rapidly decreased due to micro crack propagation in the all cases when 60% loading was considered in compressive condition.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.723-730
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• 2018

Objective : The aim of the present study was to identify whether the deformity angular ratio (DAR) influences the occurrence of complications after posterior vertebral column resection (PVCR) and to establish the DAR cut-off value. Methods : Thirty-six consecutive patients undergoing PVCR from December 2010 to October 2016 were reviewed. The relationships between the total, sagittal, and coronal DAR and complications were assessed using receiver operator characteristics curves. The patients were divided into two groups according to a reference value based on the cut-off value of DAR. Demographic, surgical, radiological, and clinical outcomes were compared between the groups. Results : There were no significant differences in the patient demographic and surgical data between the groups. The cut-off values for the total DAR (T-DAR) and the sagittal DAR (S-DAR) were 20.2 and 16.4, respectively (p=0.018 and 0.010). Both values were significantly associated with complications (p=0.016 and 0.005). In the higher T-DAR group, total complications (12 vs. 21, p=0.042) and late-onset complications (3 vs. 9, p=0.036) were significantly correlated with the T-DAR. The number of patients experiencing complications (9 vs. 11, p=0.029) and the total number of complications (13 vs. 20, p=0.015) were significantly correlated with the S-DAR. Worsening intraoperative neurophysiologic monitoring was more frequent in the higher T-DAR group (2 vs. 4) than in the higher S-DAR group (3 vs. 3). There was no difference in neurological deterioration between the groups after surgery. Conclusion : Both the T-DAR and the S-DAR are risk factors for complications after PVCR. Those who had a T-DAR >20.2 or S-DAR >16.4 experienced a higher rate of complications after PVCR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.493-502
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• 2019

Recently, the installation of renewable energy including PV systems in distribution systems has increased energetically to cope with climate change and energy shortages according to the government's policy of renewable energy 3020. On the other hand, the electrical performance and lifespan of PV modules installed outdoors can be decreased considerably due to a range of deterioration phenomena depending on the ambient environmental factors. To overcome these problems, replacement of degraded PV modules with new ones is increased before the lifespan guaranteed by the makers of PV modules. Therefore, this paper proposes a disposal diagnosis algorithm to evaluate the time interval of the optimal replacement for PV modules according to performance degradation rate of PV modules. In addition, this study modeled an economic evaluation, which is composed of the cost and benefit of PV systems. From the simulation results based on the proposed modeling and algorithm to consider the performance degradation rate specifically, the replacement approach was found to have the best B/C ratio in 10th year with a 3[%] degradation rate and the disposal diagnosis algorithm of PV modules are useful and practical tools for economic evaluations of the replacement of PV modules.

• 한국노년학
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• v.32 no.4
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• pp.993-1011
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• 2012

The purpose of this study is to investigate the factors associated with the incidence and the transition of disability among Korean older adults. Samples consist of 1,454(42.7%) men and 2,032(58.3%) women aged 65 and over who participated in the 1st and 2nd wave of the Korea Longitudinal Study of Aging: KLOSA. To estimate the level of disability, ADL and IADL disability indexes are used. As the results, major risk factors for ADL/IADL disability incidence include injury, vision problem, cognitive function, depression, health behavior, socioeconomic characteristics and age. Among the normal older adults, the odds ratio of having dementia symptoms at 2nd wave(2008) are 2.0 times greater for the older adults who have less cognitive function than those who don't have at 1st wave(2006). Among the older adults with chronic diseases, the odds ratio of having disability at 2nd wave are 1.8 times greater for the older persons who have depression than those who don't have at 1st wave. Secondly, concerning the predictors affecting the disability transition among the disabled older adults at 1st wave, the likelihood of remaining at the same level or deteriorating the level of IADL disability, as compared with improving the level, is associated with having less instrumental support or being older. These results indicate that it is necessary to prefer multilevel intervention in order not only to prevent the incidence of disability, but also to prolong the deterioration of disability in the older adults.

• Animal Bioscience
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• v.34 no.4
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• pp.662-669
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• 2021

Objective: Effects of linseed oil (LO) supplementation on the fat content and fatty acid profile of breast meat, and the expression of three genes in the liver, breast muscle and fat tissues of commercial 154-day-old hybrid male turkeys were investigated. Methods: The animals in the control group were fed a commercially available feed and received no LO supplementation (n = 70), whereas animals in the LO group (n = 70) were fed the same basic diet supplemented with LO (day 15 to 21, 0.5%; day 22 to 112, 1%). The effect of dietary LO supplementation on fatty acid composition of breast muscle was examined by gas chromatography, and the expression of fatty acid desaturase 2 (FADS2), peroxisome proliferator activated receptor gamma (PPARγ), and insulin-like growth factor 1 (IGF1) genes was analysed by means of quantitative reverse transcription polymerase chain reaction. Results: The LO supplementation affected the fatty acid composition of breast muscle. Hepatic FADS2 levels were considerably lower (p<0.001), while adipose tissue expression was higher (p<0.05) in the control compared to the LO group. The PPARγ expression was lower (p<0.05), whereas IGF1 was higher (p<0.05) in the fat of control animals. There were no significant (p>0.05) differences in FADS2, PPARγ, and IGF1 gene expressions of breast muscle; however, omega-6/omega-3 ratio of breast muscle substantially decreased (p<0.001) in the LO group compared to control. Conclusion: Fatty acid composition of breast meat was positively influenced by LO supplementation without deterioration of fattening parameters. Remarkably, increased FADS2 expression in the liver of LO supplemented animals was associated with a significantly decreased omega-6/omega-3 ratio, providing a potentially healthier meat product for human consumption. Increased PPARγ expression in fat tissue of the LO group was not associated with fat content of muscle, whereas a decreased IGF1 expression in fat tissue was associated with a trend of decreasing fat content in muscle of the experimental LO group.

• Korean Journal of Environment and Ecology
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• v.35 no.1
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• pp.37-47
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• 2021

This study carried out the plant sociological survey of Abies nephrolepis forest in Mt. Seorak, which is in danger of deterioration due to the accelerated climate change. We examined seventy quadrats obtained from the survey and used the TWINSPAN technique to classify communities. We then performed the DCA method for the sequence analysis and analyzed the characteristics of each community. A. nephrolepis forest of Mt. Seorak is composed of four communities (A. nephrolepis-Lonicera caerulea var. edulis community, A. nephrolepis-Acer komarovii community, A. nephrolepis-Ac. pseudosieboldianum community, and A. nephrolepis-Betula costata community). Each community showed a different distribution according to location because different microenvironments are formed depending on location such as altitude and slope direction, resulting in different species composition. Each community showed differences in environmental characteristics such as altitude, rock ratio, soil characteristics, and litter layer thickness. As a result, there were significant differences between communities in the number of species and individuals, coverage, tree size, and species diversity, as well as differences in species composition. The A. nephrolepis-L. caerulea var. edulis and A. nephrolepis-Ac. komarovii communities were located in high altitude with high rock ratios and had little development of tree layer. On the other hand, the A. nephrolepis-Ac. pseudosieboldianum and A. nephrolepis-B. costata communities were relatively in low altitude with high soil ratio and had the development of tree layer with high species diversity.