• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.19-23
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• 2004

The Hertzian indentation contact damage behavior of porous alumina with controlled pore shape was investigated by experiments. Porous alumina ceramics containing well-defined pore shape, size and distribution were prepared by incorporation of fugitive spherical starch. Porous alumina with isolated pore structure was prepared with porosity range up to 30%. The indentation stress-strain curves of porous alumina were constructed. Elastic modulus and yield stress can be obtained from the stress-strain relationship. Impulse excitation method for the measurement of elastic modulus was also conducted as well as Hertzian indentation and was confirmed as a useful tool to evaluate the elasticity of highly porous ceramics. Elastic modulus of the inter-connected pore structure is more sensitive to porosity than that of the isolated pore structure. When the specimen had isolated pore structure, higher yield point was obtained than it had inter-connected pore structure. This study proposed that the elastic modiulus of porous ceramics is strongly related to not only porosity, but also the structure of pore.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.387-401
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• 2017

This study was performed in order to investigate disease, insect damage, growth and yield characteristics of green maize by organic paddy-upland rotation system. This experiment also was to select optimum variety for organic paddy-upland rotation cultivation. This experiment was conducted at Anseong-si Gyeonggi province of Korea in 2016. The varieties used in this study are green maize of total 8 varieties. Green maize was planted at rotational upland field and continuing upland field and tested for comparison. In case of average occurrence of 4 major disease for green maize, rotational upland field was higher than that of continuing upland field. Heukjinjuchal and Daehakchal were the lowest occurrence by less than 2% among 8 varieties. Average damage of 8 varieties by Ostrinia furnacalis larva, which is the main pest in green maize was higher in rotational upland field than that of continuing upland field. Chalok 4 and Heugjeom 2 were judged to be resistant varieties to 4 major disease among 8 varieties. The average yield of green maize per 10a in rotational upland field decreased to 85% level of continuing upland field and Chalok 4 showed the highest yield by 789.0 kg/10a among 8 varieties. The most suitable varieties in organic paddy-upland rotation system were judged to be Chalok 4, Heukjinjuchal and Heukjeom 2.

• Polymer(Korea)
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• v.35 no.3
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• pp.203-209
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• 2011

Two smooth and textured surfaced HDPE geomembranes (GMs) were cut into dumbbell shape and notched where depth of the notch produced a ligament thickness of 10% to 90% of the nominal thickness with the specimen at 10% interval. A series of laboratory simulation test for installation damage were carried out at different loading cycles on HDPE GMs in accordance with ISO 10722 test method and the effect of number of loading cycle on installation damage was compared. It was found that yield stress and elongation at yield point decreased gradually as the notch depth was increased. Both installation damaged and notched, GMs were used to understand stress crack behavior and this behavior was observed through NCTL test at $50{\pm}1^{\circ}C$ at different yield stresses immerging in pH 4 and pH 12 buffer solutions. Over 35% tensile load, GMs became vulnerable to stress cracking. Both damaged and notched GMs showed the same trend. Especially, notched GMs showed less strength than installation damaged GMs at every stress cracking test condition.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.313-318
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• 2015

In the year 2013, onions cultivation in Jeonnam province suffered by frost-pillar damage. To reveal the aspects of the cause and outbreak, we surveyed those damaged areas. Usually the frost-pillar damage occurred in February. But the outbreak aspect is so unforeseeable. In 2013, the damage was shown as 10.6% in onion fields including paddy fields, but no damage was noticed in 2014. The damage was noticed as 77.8% in paddy fields and 30.1% in upland. And, by the difference of the onion transplanting date, it occurred as 0.7% by the middle of November to the early of November, 22% by the middle of November and 69.0% by the early of December. If one performed the supplementary planting at $3^{rd}$ week of February, the highest survival percent was observed as 53.3%. If the date is early, another frost-pillar damage was occurred. If it's late, the damaged plant was perished with dry. In any case, we found improper transplanting caused the yield decrease. Therefore, we recommend the timely transplanting is the most important way for the prevention of frost-pillar damage in the onion cultivation.

• Research in Plant Disease
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• v.29 no.3
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• pp.220-233
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• 2023

The phenomena of global warming has led to an increase in the average air temperature in temperate climates. Springtime frost damage is becoming more common, and after a period of dormancy, damage to buds, blooms, and developing fruits is greater significant than damage from low winter temperatures. Peaches are a crucial crop among moderate fruits. Spring frost damage in peaches can have a negative effect on crop growth, yield, and quality. It is noteworthy that these plants have evolved defenses against spring frost damage while being exposed to a variety of low temperatures in the early spring. In this current review, recent research advancements on spring frost damage avoidance in peaches were deliberated. Additionally, adaptive mechanisms of peach, such as deacclimation and reacclimation, were emphasized. Moreover, the emerging advancements using various omics approaches revealed the peach physiology and molecular mechanisms comprehensively. Furthermore, the use of chemical products and understanding the spring frost mechanisms through the use of environmental chamber temperature stimulation and infrared thermography studies were also discussed. This review is essential groundwork and paves the way to derive and design future research for agronomists and horticulturalists to overcome the challenges of spring frost damage avoidance and crop management in these circumstances.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.1
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• pp.1-9
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• 2022

This study was carried out to compare the DMY (dry matter yield) of IRG (Italian ryegrass) in the southern coastal regions of Korea due to seasonal climate scenarios such as the Kaul-Changma (late monsoon) in autumn, extreme winter cold, and drought in the next spring. The IRG data (n = 203) were collected from various Reports for Collaborative Research Program to Develop New Cultivars of Summer Crops in Jeju, 203 Namwon, and Yeungam from the Rural Development Administration - (en DASH). In order to define the seasonal climate scenarios, climate variables including temperature, humidity, wind, sunshine were used by collected from the Korean Meteorological Administration. The discriminant analysis based on 5% significance level was performed to distinguish normal and abnormal climate scenarios. Furthermore, the DMY comparison was simulated based on the information of sample distribution of IRG. As a result, in the southern coastal regions, only the impact of next spring drought on DMY of IRG was critical. Although the severe winter cold was clearly classified from the normal, there was no difference in DMY. Thus, the DMY comparison was simulated only for the next spring drought. Under the yield comparison simulation, DMY (kg/ha) in the normal and drought was 14,743.83 and 12,707.97 respectively. It implies that the expected damage caused by the spring drought was about 2,000 kg/ha. Furthermore, the predicted DMY of spring drought was wider and slower than that of normal, indicating on high variability. This study is meaningful in confirming the predictive DMY damage and its possibility by spring drought for IRG via statistical simulation considering seasonal climate scenarios.

• The Plant Pathology Journal
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• v.21 no.2
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• pp.87-92
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• 2005

The structural differences between healthy and diseasedpanicle necks caused by Pyricularia oryzae were observed using electron-microscope. In the diseased panicle neck, the infection hyphae of the rice blast pathogen grew through the sclerenchymatous fiber tissue and reached to the central internal lacuna. Since the pathogen grew through the sclerenchymatous fiber tissues, the vascular bundle composed with xylem and phloem had been destroyed and finally the nutrients from the leaf and stem were not able to be transported into the grains. Infection of panicle base by the blast pathogen until 20 days after heading caused more than 50% of yield loss in both Jinmibyeo and Chucheongbyeo. There was a positive correlation between incidence of the panicle blast and rice yield losses. The regression equations between incidence of the panicle blast and yield losses were y= -3.61+496.7 ($R^2$=0.70) in Jinmibyeoand y=-3.93+520.2 ($R^2$=0.82) in Juanbyeo. The panicleblast caused deterioration of grain quality. Healthy grain rate was reduced by increase of panicle blast infection.

• Journal of Environmental Science International
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• v.22 no.2
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• pp.235-242
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• 2013

The purpose of this article is analyzing the impacts of climate change on winter chinese cabbage yield in Korea, with employing a panel data regression model. Our results show that there is a negative impacts of high temperature and precipitation amount on winter chinese cabbage yields. Especially high temperature and rainfall in September cause serious damage to winter chinese cabbage yield. According to the reduction schedule on greenhouse gas emission(RCP 4.5 scenario.), winter chinese cabbage yield would be 7.7% lower than it is, for reasons of high temperature and rainfall damages by the end of 21st century.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1503-1510
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• 2012

The purpose of this article is analyzing the impacts of climate change on red pepper yield in Korea, with employing a panel data regression model. Our results show that there is a negative impacts of high temperature and precipitation amount on red pepper yields. Especially high temperature and rainfall in July cause serious damage to red pepper yield. According to the reduction schedule on greenhouse gas emission(RCP 8.5 scenario.), red pepper yield would be 25.4% lower than it is, for reasons of high temperature and rainfall damages by the end of 21st century.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.3
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• pp.141-147
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• 2019

The purpose of this study was to determine the effect of waterlogging duration on the growth characteristics and productivity of forage corn at different growth stages under paddy field conditions. Treatments consisted of waterlogging at two growth stages (V7 or V14) for four waterlogging durations (no waterlogging, 48 hours, 72 hours, and 96 hours, respectively). The V14 growth stage was more vulnerable to waterlogging than the V7 stage. Among the waterlogging durations, the lodging score increased at 48 hours. The stem height of forage corn decreased with the increase in waterlogging duration at the different growth stages (V7 and V14). Increase in waterlogging duration reduced the stem dry matter yield, ear dry matter yield, and total dry matter yield at both growing stages (V7 and V14). The waterlogging treatments at the V14 stage affected ear dry matter yield more than those at the V7 growing stage. Thus, the management of forage corn under paddy field conditions must be strengthened during early (V7) and grain fill stages (V14). When waterlogging occurs, surface and subsurface drainage should be implemented within 48 hours to control (no waterlogging) the groundwater level and, thus, minimize economic losses due to forage corn damage.