• Journal of Embryo Transfer
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• v.23 no.4
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• pp.257-261
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• 2008

The objective of present study was to investigate the effect of seasons on reproductive performance of Hanwoo and Holstein heifers. Heat stress in summer or cold stress in winter stress to Hanwoo and Holstein heifers may bring reproduction failure, which would pose an important economic loss, even around Daegwallyeong region located in high mountainous area. Seasonal differences in the serum levels of LH, FSH and progesterone ($P_4$) in response to environmental factors (hot and cold) out of 20 pubertal Hanwoo heifers in Daegwallyeong, Gangwon Province and 20 non-lactating Holstein heifers in Chonan city of Republic of Korea at 2-3 years of age were compared. Blood samples for hormonal analysis were from jugular vein after detection of estrus repeatedly over four seasons within four-week intervals (Spring: May to June, Summer: July to August, Autumn: October to November and Winter: January to February). In Hanwoo heifer population, averages of LH and FSH concentration in spring and in summer were greater compared to those in winter (p<0.05). LH or FSH levels tended to be greater (p=0.06) in spring and less (p=0.09) in winter compared to the levels in autumn. Only in summer, cattle seemed to show lower LH or FSH secretion (p<0.05). Similar to the results in Hanwoo heifers, the serum concentrations of LH and FSH in Holstein heifers decreased further by heat stress in summer when P 4 levels were high during luteal phase. The results demonstrate significant effect of summer heat on reproduction of Hanwoo or Holstein heifers. Although parameters indicating the extent of heat stress were not measured in this study, we suggest that serum hormone levels could be considered as successful indicators of summer heat stress condition for Hanwoo and Holstein heifers even under rather cool summer climate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.1
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• pp.63-77
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• 2015

Tsunami take away life, wash houses away and bring devastation to social infrastructures such as breakwaters, bridges and ports. The coastal structure targeted object in this study can be damaged mainly by the wave pressure together with foundation ground failure due to scouring and liquefaction. The increase of excess pore water pressure composed of oscillatory and residual components may reduce effective stress and, consequently, the seabed may liquefy. If liquefaction occurs in the seabed, the structure may sink, overturn, and eventually increase the failure potential. In this study, the bore was generated using the water level difference, its propagation and interaction with a vertical revetment analyzed by applying 2D-NIT(Two-Dimensional Numerical Irregular wave Tank) model, and the dynamic wave pressure acting on the seabed and the surface boundary of the vertical revetment estimated by this model. Simulation results were used as input data in a finite element computer program(FLIP) for elasto-plastic seabed response. The time and spatial variations in excess pore water pressure ratio, effective stress path, seabed deformation, structure displacement and liquefaction potential in the seabed were estimated. From the results of the analysis, the stability of the vertical revetment was evaluated.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.363-375
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• 2015

This research investigated the effects of diameter and material of energy frame on the impact velocity or strain rate of Strain Energy Frame Impact Machine (SEFIM). The impact speed of SEFIM have been clearly affected by changing the diameter and material of the energy frame. The reduced diameter of the energy frame clearly increased the impact velocity owing to the higher strain at the moment of coupler breakage. And, titanium alloy energy frame produced the fastest speed of impact among three materials including steel, aluminum and titanium alloys because titanium alloy has faster wave velocity than steel. But, aluminium energy frame was broken during impact tests. In addition, the tensile stress versus strain response of high performance fiber reinforced cementitious composites at higher and wider strain rates between 10 and 72 /sec was successfully obtained by using four different energy frames.

• 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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.187-195
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• 2019

The needs for precise diagnostics and farm management-decision aids have increased to reduce the risk of climate change and environmental stress. Crop simulation models have been widely used to search optimal solutions for effective cultural practices. However, limited knowledge on physiological responses to environmental variation would make it challenging to apply crop simulation models to a wide range of studies. Advanced research facilities would help investigation of plant response to the environment. In the present study, the sunlit controlled environment chambers, known as Korean SPAR (Soil-Plant-Atmosphere-Research) system, was developed by renovating existing SPAR system. The Korean SPAR system controls and monitors major environmental variables including atmospheric carbon dioxide concentration, temperature and soil moisture. Furthermore, plants are allowed to grow under natural sunlight. Key physiological and physical data such as canopy photosynthesis and respiration, canopy water and nutrient use over the whole growth period are also collected automatically. As a case study, it was shown that the Korean SPAR system would be useful for collection of data needed for understanding the growth and developmental processes of a crop, e.g., soybean. In addition, we have demonstrated that the canopy photosynthetic data of the Korean SPAR indicate the precise representation of physiological responses to environment variation. As a result, physical and physiological data obtained from the Korean SPAR are expected to be useful for development of an advanced crop simulation model minimizing errors and confounding factors that usually occur in field experiments.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.264-270
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• 2017

Brassinosteroid (BR), a plant steroid hormone, plays a critical role in the growth and developmental processes through its canonical signaling and crosstalk with various internal and external signaling pathways. Recent studies have revealed the essential interplay mechanisms between BR and ABA during seed germination and early seedling establishment. However, molecular mechanisms for this important signaling crosstalk are largely unknown. To understand the crosstalk between BR-mediated signaling pathways and ABA functions during early seedling development, we carried out a comparative genome-wide transcriptome analysis with an Agilent Arabidopsis $4{\times}44K$ oligo chip. We selected and compared the expression patterns of ABA response genes in ABA-insensitive bes1-D mutant with wild type seedlings on which ABA was exogenously applied. As a result, we identified 2,353 significant differentially expressed genes (DEGs) in ABA-treated bes1-D and wild type seedlings. GO enrichment analysis revealed that ABA signaling, response, and metabolism were critically down-regulated by BR-activated signaling pathways. In addition, the genome-wide transcriptome analysis data revealed that BR-regulated signaling pathways were tightly connected to diverse signal cues including abiotic/biotic stress, auxin, ROS etc. In this study, we newly identified the molecular mechanisms of BR-mediated repression of ABA signaling outputs. Also, our data suggest that interplay among diverse signaling pathways is critical for the adaptive response of the plant to various environmental factors.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.135-142
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• 2015

Floating offshore structures should be designed by considering the most extreme environmental loadings which may be encountered in their design life. The most severe loading on a wave-offshore wind hybrid power generation system is wave loads. The principal parameters of wave loads are wave length, wave height and wave direction. The wave loads have different effects on the structural behavior characteristic depending on the combination of wave parameters. Therefore, the process of investigation for critical loads based on the individual wave loading parameter is need. Namely, the equivalent design wave should be derived by finding the wave condition which generates the maximum stress in entire wave conditions. Through a series of analysis, an equivalent regular wave height can be obtained which generates the same amount of the hydrodynamic loads as calculated in the response analysis. The aim of this study is the determination of equivalent design wave regarding to characteristic global hydrodynamic responses for wave-offshore wind hybrid power generation system. It will be utilized in the global structural response analysis subjected to selected design waves and this study also includes an application of global structural analysis.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.10
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• pp.1433-1439
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• 2000

An experiment was carried out with 48 IVRI 2CQ rats 6-8 week old, weighing 50-100 g, to study the effect of lead exposure on antioxidant defense, lipid peroxide level, status of thiol groups and concentration of lead in the liver and kidneys at the end of the exposure and also after withdrawal of lead administration. Twenty four rats were given lead at a daily dose rate of 1 mg lead/2 ml of distilled water/kg body weight as lead acetate solution intraperitoneally for a period of 30 days. Another 24 control rats received 2 ml of sterile normal saline solution (0.85% NaCl)/kg body weight in an identical manner. A many-fold increase in concentration of lead was associated with a non-significant (p>0.05) decrease in the activities of superoxide dismutase (SOD) in the liver (27%) and kidneys (12%) and catalase in kidneys (22%). A significant (p<0.05) increase in lipid peroxide level was recorded in the liver (40%) compared with control values. There were significant (p<0.05) decreases in the total thiol and protein bound thiol contents in liver and an increase in non-protein bound thiol groups in the kidneys of lead exposed rats. During the 10 day observation period after withdrawal of lead administration, no significant change was observed with respect to any of the above parameters indicating that a 10 day withdrawal period was not enough for restoration of normality. It is concluded that the magnitude of response and the resultant changes in the lipid peroxide concentration, and the activities of SOD and catalase were not identical in the liver and kidneys of lead-exposed rats.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1269-1281
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• 2016

This study evaporative cooling system a heat wave climate change and reduction of the inside and outside thermal environment change research. Measurement items included micro meteorological phenomena and measured comfort indices. A micro meteorograph of temperature, relative humidity, surface temperature, and the comfort indices of WBGT, UTCI, and PMV were measured. The difference in inside and outside temperatures were compared for different land types, with the largest difference found in Type A ($4.81^{\circ}C$), followed by Type B ($4.40^{\circ}C$) and Type C ($3.12^{\circ}C$). Relative humidity was about 10.43% higher inside due to water injection by the evaporative cooling system. Surface temperature was inside about $6.60^{\circ}C$ higher than the outside all types. WBGT were Type A ($3.50^{\circ}C$) > Type B ($2.71^{\circ}C$) > Type C ($1.88^{\circ}C$). UTCI was low heat stress inside than outside all types. PMV was analysed Type C for inside predicted percentage of dissatisfied 75%, other types was percentage of dissatisfied 100% by inside and outside. Correlation analysis between land cover type and temperature, surface temperature, pmv, utci. T-test analysed inside and outside temperature difference was significant in all types of land.

• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.392-399
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• 2014

Plant senescence is one of the survival strategies to use limited nutrients efficiently during growth, development and adaptation. In this study, we isolated a gene (PagSEN1) homologous to SENESCENCE 1 from Populus alba ${\times}$ P. glandulosa. The PagSEN1 gene encodes a putative protein consisting of 243 amino acids containing a rhodanese domain. Southern blot analysis suggested that two copies of the PagSEN1 gene are present in the poplar genome. We characterized its transcriptional expression under various conditions mimicking senescence and environmental stresses. The PagSEN1 was expressed most strongly in mature leaves but most weakly in roots. The gene was significantly up-regulated by treatments with mannitol, NaCl, ABA and JA, but not by cold, SA and GA3. These results indicate that PagSEN1 is involved in senescence response induced by environmental stresses.