• Journal of Forest and Environmental Science
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• v.37 no.4
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• pp.315-322
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• 2021

The aim of this study was to investigate the sensitivity to environmental stress, and changes in the photosynthesis capacity in Abies koreana seedlings by age and to suggest the most effective age for restoration. To identify these physiological characteristics of A. koreana, the chlorophyll fluorescence and photosynthetic capacity of 1-, 2-, 3-, 5- and 6-year-old A. koreana seedlings were observed from June 2020 to June 2021. The maximum quantum efficiency of Photosystem II (Fv/Fm), a chlorophyll fluorescence measurement parameter, was strongly positively correlated with the monthly average temperature (1-year-old seedling: r=0.8779, 2-year-old seedling: r=0.8605, 3-year-old seedling: r=0.8697, 5-year-old seedlings: r=0.8085, and 6-year-old seedlings: r=0.8316). The Fv/Fm values were the lowest in winter (November 2020-March 2021). In addition, the Fv/Fm values of 1-, 2-, and 3-year-old seedlings in winter were lower than that of 5- and 6-year-old seedlings, while the Fv/Fm values in summer were relatively higher than those in winter. Further, the Fv/Fm values of seedlings of all ages decreased in August 2020, when the monthly average temperature was the highest. In particular, 1-year-old to 3-year-old seedlings showed Fv/Fm values less than 0.8. Further, the photosynthetic capacity measured in August 2020 increased with increasing seedling age. The analysis of variance results for summer Fv/Fm values showed significant differences in age-specific averages (p<0.05), and Duncan's multiple range test showed significant differences between 5- and 6-year-old seedlings and 1-, 2-, and 3-year-old seedlings (p<0.05). These results suggested that the 5- and 6-year-old seedlings were less sensitive to environmental stress and showed better photosynthetic capacity than the 1-, 2-, and 3-year-old seedlings. Therefore, 5-year-old or older A. koreana seedlings can be used as restoration materials because they can show increased adaptability and stable growth during transplantation due to their relatively high environmental resistance and photosynthetic capacity.

• Journal of the Korean Institute of Gas
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• v.25 no.2
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• pp.64-71
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• 2021

Research on polymer matrix composites with excellent molding processability and mechanical properties in the automotive field including hydrogen fuel cell electric vehicles is expanding to Computer-Aided Engineering (CAE) to support the design of materials with specific mechanical properties. CAE automation requires the prediction of the mechanical properties and behavior of materials. Unlike single materials, the mechanical properties prediction of polymer matrix composites is difficult to explain with formulas because the mechanical behavior is complicated to be explained only by the relationship between the matrix and the filler. In this study, the stress-strain curve according to the composition of polymer matrix composites, which was difficult to predict due to its sensitivity to large plastic deformation and composition, was predicted based on machine learning of the test data. The developed model finds a complex correlation between matrix and filler types and compositions, and predicts the total stress-strain curve meaningfully even in the absence of learned test data. It is expected that the material design AI system can be completed in the future based on the developed model that predicts the mechanical properties of polymer matrix composites even for the combination and composition that have not been learned.

• Journal of Korean Academy of Nursing
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• v.45 no.2
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• pp.280-292
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• 2015

Purpose: In this study a system dynamics methodology was used to identify correlation and nonlinear feedback structure among factors affecting unplanned extubation (UE) of ICU patients and to construct and verify a simulation model. Methods: Factors affecting UE were identified through a theoretical background established by reviewing literature and preceding studies and referencing various statistical data. Related variables were decided through verification of content validity by an expert group. A causal loop diagram (CLD) was made based on the variables. Stock & Flow modeling using Vensim PLE Plus Version 6.0b was performed to establish a model for UE. Results: Based on the literature review and expert verification, 18 variables associated with UE were identified and CLD was prepared. From the prepared CLD, a model was developed by converting to the Stock & Flow Diagram. Results of the simulation showed that patient stress, patient in an agitated state, restraint application, patient movability, and individual intensive nursing were variables giving the greatest effect to UE probability. To verify agreement of the UE model with real situations, simulation with 5 cases was performed. Equation check and sensitivity analysis on TIME STEP were executed to validate model integrity. Conclusion: Results show that identification of a proper model enables prediction of UE probability. This prediction allows for adjustment of related factors, and provides basic data do develop nursing interventions to decrease UE.

• Structural Engineering and Mechanics
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• v.16 no.6
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• pp.749-769
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• 2003

The structural deterioration of concrete structures due to reinforcement corrosion is a major worldwide problem. Service life of the age-degraded concrete structures is governed by the protective action provided by the cover concrete against the susceptibility of the reinforcement to the corrosive environment. The corrosion of steel would result in the various corrosion products, which depending on the level of the oxidation may have much greater volume than the original iron that gets consumed by the process of corrosion. This volume expansion would be responsible for exerting the expansive radial pressure at the steel-concrete interface resulting in the development of hoop tensile stresses in the surrounding cover concrete. Once the maximum hoop tensile stress exceeds the tensile strength of the concrete, cracking of cover concrete would take place. The cracking begins at the steel-concrete interface and propagates outwards and eventually resulting in the through cracking of the cover concrete. The cover cracking would indicate the loss of the service life for the corrosion-affected structures. In the present paper, analytical models have been developed considering the residual strength of the cracked concrete and the stiffness provided by the combination of the reinforcement and expansive corrosion products. The problem is modeled as a boundary value problem and the governing equations are expressed in terms of the radial displacement. The analytical solutions are presented considering a simple 2-zone model for the cover concrete viz. cracked or uncracked. A sensitivity analysis has also been carried out to show the influence of the various parameters of the proposed models. The time to cover cracking is found to be function of initial material properties of the cover concrete and reinforcement plus corrosion products combine, type of rust products, rate of corrosion and the residual strength of the cover concrete. The calculated cracking times are correlated against the published experimental and analytical reference data.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7103-7110
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• 2015

The present study was conducted to investigate the effect of ${\gamma}$-radiation alone or combined with a cytotoxic drug, simvastatin, on viability and cell cycling of a myeloma cell line. P3NS1 myeloma cells were treated with the selected dose of simvastatin ($0.1{\mu}M/l$) 24 hours prior to ${\gamma}$-irradiation (0.25, 0.5 and 1Gy). The cell viability, induction of apoptosis, cell death, cell cycling, generation of ROS, and expression of P53, Bax, Bcl2, caspase3, PARP1 and Fas genes were estimated. The results indicated that simvastatin ($0.1{\mu}M/l$) treatment for 24 hours prior to ${\gamma}$-irradiation increased cell death to 37.5% as compared to 4.81% by radiation (0.5Gy) alone. It was found that simvastatin treatment before irradiation caused arrest of cells in G0/G1 and G2/M phases as assessed using flow cytometry. Interestingly, simvastatin treatment of P3NS1 cells increased the intracellular ROS production and decreased antioxidant enzyme activity with increased P53, Bax and Caspase3 gene expression while that of Bcl2 was decreased. Consequently, our results indicated that pre-treatment with simvastatin increased radio sensitivity of myeloma tumor cells in addition to apoptotic effects through an intrinsic mitochondrial pathway.

• Korean Journal of Materials Research
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• v.28 no.8
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• pp.435-439
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• 2018

MA Al alloys are examined to determine the effects of alloying of Mg and Cu and rolling on tensile deformation behavior at 748 K over a wide strain rate range($10^{-4}-10^3/s$). A powder metallurgy aluminum alloy produced from mechanically alloyed pure Al powder exhibits only a small elongation-to-failure(${\varepsilon}_f$ < ~50%) in high temperature(748 K) tensile deformation at high strain rates(${\acute{\varepsilon}}=1-10^2/s$). ${\varepsilon}_f$ in MA Al-0.5~4.0Mg alloys increases slightly with Mg content(${\varepsilon}_f={\sim}140%$ at 4 mass%). Combined addition of Mg and Cu(MA Al-1.5%Mg-4.0%Cu) is very effective for the occurrence of superplasticity(${\varepsilon}_f$ > 500%). Warm-rolling(at 393-492 K) tends to raise ${\varepsilon}_f$. Lowering the rolling-temperature is effective for increasing the ductility. The effect is rather weak in MA pure Al and MA Al-Mg alloys, but much larger in the MA Al-1.5%Mg-4.0%Cu alloy. Additions of Mg and Cu and warm-rolling of the alloy cause a remarkable reduction in the logarithm of the peak flow stress at low strain rates (${\acute{\varepsilon}}$< ~1/s) and sharpening of microstructure and smoothening of grain boundaries. Additions of Mg and Cu make the strain rate sensitivity(the m value) larger at high strain rates, and the warm-rolling may make the grain boundary sliding easier with less cavitation. Grain boundary facets are observed on the fracture surface when ${\varepsilon}_f$ is large, indicating the operation of grain boundary sliding to a large extent during superplastic deformation.

• Journal of Animal Science and Technology
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• v.52 no.1
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• pp.57-64
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• 2010

This study was conducted to compare the aspects of behavior between miniature pigs and conventional sows during gestation and lactation periods. Miniature pigs and conventional sows at 3 parity were used in this experiment with 4 pigs per treatment. The behavioral patterns and stereotyped behaviors were observed on day 60 and 90 of gestation, at farrowing, and on day 10 of lactation before and after the feeding. On 60 and 90 days of pregnancy, both treatments showed the tendency of frequent lateral lying rather than other postures. On ventral lying, eating and drinking, miniature pigs spent more time than conventional pigs at day 90 of gestation (P<0.01, P=0.0539, P<0.05, respectively). The occurrence of stereotyped behaviors included bar biting and bar mouth chewing. At 90 day of pregnancy was observed, conventional pigs was higher than miniature pigs (P<0.05). At farrowing, miniature pigs spent more time on ventral lying, standing and walking than conventional sows (P<0.05), however, there were more frequency of drinking and eating. And on day 10 of lactation, there was no significant difference in stereotyped behaviors between miniature pigs and conventional sows. In conclusion, miniature pigs were generally more sensitive than conventional sows although sows were reared in stall during gestation and lactation period and the behavioral pattern during lactating period showed the similarity between miniature pigs and conventional sows for protection of nursing pigs. In consideration of the general reproductive performance of conventional sows, the high sensitivity and stress of miniature pigs did not affect the reproductive performance of miniature pigs.

• Journal of Oriental Neuropsychiatry
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• v.23 no.3
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• pp.63-76
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• 2012

Objectives : The aim of this study was to investigate the value and efficacy of BDI, STAI, STAXI, ISI, and SCL-90-R in correlation with depression, anxiety, and insomnia patients. Methods : A total of 39 patients, who were diagnosed with depression, anxiety, and insomnia were evaluated using BDI, STAI, STAXI, ISI, and SCL-90-R. They were then statistically analyzed. Results : 1. BDI scores of depression patients were significantly different from other patients. 2. BDI scores of depression patients had strong positive correlation with STAI-S, and STAI-T scores. 3. STAI-S scores of anxiety patients had positive correlation with BDI, and ISI scores. 4. SCL-90-R depression subscale scores of depression patients had strong positive correlation with somatization, obsessive compulsive, interpersonal sensitivity, anxiety, hostility, phobic anxiety, paranoid ideation, psychoticism, global severity index, and positive symptom total subscale scores. 5. SCL-90-R anxiety subscale scores of anxiety patients had strong positive correlation with somatization, obsessive compulsive, depression, phobic anxiety, and global severity index subscale scores. Phobic anxiety subscale scores had strong positive correlation with anxiety, global severity index, and positive symptom total subscale scores. Conclusions : The result findings are expected to serve as a useful resource in future stress-related depression, anxiety, and insomnia case reports and clinical research in oriental neuropsychiatry.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.3
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• pp.220-226
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• 2005

We investigated the effect of $O_3$ on the photosynthetic characteristics of oriental plane (Platanus orientalis L.) that is used as a side tree or ornamental tree in Korea. Two-year-old oriental plane seedlings were transplanted to pots and transferred into a closed $O_3$ chamber, Photosynthetic pigment content and photosynthetic characteristics of leaves were measured every three weeks during 100 ppb $O_3$ fumigation. There was no visible foliar injury by $O_3$ exposure and the content of photosynthetic pigments did not show significant differences between control and $O_3$-treated seedlings. But photosynthetic rate, stomatal conductance, and water use efficiency in leaves of $O_3$-treated seedlings were reduced after six weeks of ozone fumigation. In addition, reduction of carboxylation efficiency and photochemical efficiency was observed in leaves of $O_3$-treated seedlings after three weeks and six weeks. In accordance with our results, carboxylation efficiency, the most sensitive parameter to $O_3$ stress, was considered to be a suitable indicator of $O_3$ sensitivity.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.1 s.120
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• pp.88-93
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• 2007

Since the 1990s, the application of Kentucky bluegrass cultivars has increased in newly-constructed Korean golf courses as opposed to the previously-used zoysiagrass. However, there have been few reports studying the selection and characterization of these Kentucky bluegrass cultivars under Korean weather conditions. A total of 12 Kentucky bluegrass cultivars were tested for their adaptability in environmental stresses during summer conditions in Korea in order to select the best Kentucky bluegrass cultivars for use in Korean golf courses. This study found that two Kentucky bluegrass cultivars ('Midnight' and 'Bluestone') maintained their green throughout the summer season and had a high degree of root density, as compared to the other cultivars tested. These two cultivars also had a good rate of coverage in the early growth period. These characteristics make them suitable for application on sports fields and golf courses, which receive many divots and the frequent replacement of turfgrass sod caused by both biotic and abiotic stress. Two other cultivars, the 'Ginney' and 'Nuglade', also displayed good visual quality and high rate of coverage under summer conditions. In conclusion, the 'Midnight' and 'Bluestone' cultivars performed well in areas including the maintenance of their green color, the number of roots and the rate of coverage during the summer months. These characteristics are necessary for golf courses sports fields, which receive many divots and requirethe frequent replacement of turfgrass. further research on a range of Kentucky bluegrass cultivars, including a sensitivity test for many pathogens and recovery rates from a variety of stresses, is required in the near future.