• KOREAN JOURNAL OF CROP SCIENCE
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• v.20
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• pp.115-121
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• 1975

To achieve self-sufficiency in good production, cotton should be grown after barley in the southern part of Korea. But, this cropping system reduces cotton yields and fiber qualities in the current leading cotton varieties because of the short frost-free growth period. Ethrel-treated plots shortened the time to open boll by about 20days, increased the percentage of open bolls before the first frost from 38% to 93% and increased yield by 15-38%. There are not significant differences in staple length, tensile strength of the fiber, single bollweight, 100 seeds weight and germination percentage of the seeds between Ethrel-treated and untreated plots. Ethrel should be recommended to the farmers growing cotton after barley harvest.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.684-694
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• 2018

This study describes the successful establishment of a cryopreservation protocol for Citrus limon cultivars: 'Frost Eureka limon' and 'Cook Eureka limon', using a droplet-vitrification method. The shoot tips that were excised from in vitro grown seedlings of the two cultivars were preserved in liquid nitrogen (LN) and successfully regenerated into whole plants. Excised shoot tips were pre-cultured for 1 or 2 days in 0.3 M and 0.5 M sucrose solutions at $25^{\circ}C$ and incubated in a loading solution (LS) composed of 17.5% glycerol + 17.5% sucrose in Murashige and Skoog (MS) medium for 40 min at $25^{\circ}C$. Prior to direct immersion in LN for 1 h, the shoot tips were dehydrated with plant vitrification solution 2 (PVS2) at $0^{\circ}C$ or PVS3 at $25^{\circ}C$. The frozen shoot tips were re-warmed and unloaded with 1.2 M sucrose in $\text\tiny{^1/_2}$ MS for 30 min at $25^{\circ}C$. Shoot tips were post-cultured overnight on survival medium and then micrografted onto 'trifoliate orange' (Poncirus trifoliate (L.) Raf. seedling rootstocks for recovery and to produce whole plants. The highest regrowth rates were 53.5% and 50.3% for cryopreserved shoot tips of 'Frost Eureka limon' and 'Cook Eureka limon', respectively, when pre-cultured in 0.3 M and 0.5 M sucrose concentrations in a sequencing manner, with LS and treated with PVS2 for 60 min at $0^{\circ}C$. We also investigated whether the ammonium ion concentration on post-culture medium affected the viability of the cryopreserved Citrus shoot tips. The viability of cooled samples, following culturing on woody plant media (WPM) containing $\text\tiny{^1/_4}$ ammonium nitrate overnight before micrografting, was the highest (70.3%) in 'Frost Eureka limon'. The study described here is a cost-effective and safe method to conserve Citrus fruit cultivars, for the improvement and large-scale multiplication of fruit plants and for breeding disease resistance.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.403-413
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• 2021

This paper emphasizes the effect of using poetry in the University General English education and suggests the teaching method of English education with a Frost's poem, "Out, Out- ." These days, learner-centered English education and integrative study of four linguistic functions, reading, listening, speaking and writing are considered important in the University General English class. Poetry is very effective text for the education purposes. Poetry techniques like a visual image, rhythm, rhyme, or repetition are actually mnemonics and strongly connected to the enhancement of memory and oral linguistic function. This paper suggests the specific education methods in the poetry selection, pre-reading step, reading step and after- reading step with concrete examples of "Out, Out-." These education methods through the 'oral text' can be a good and sustainable model for learner-centered education.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.224-228
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• 2006

The characteristics associated with the Alisma plantago quality and the factors as the proper harvesting time and drying temperature of Alisma plantago were examined from 2004 to 2006 at Sunchon, Southern region. The Alisma plantago cultivars tested were Sunwol and Yongjun. The highest yields of root and good quality, color and luster were obtained when harvested 22 days after first frost date and dried with $35-40^{\circ}C$ of a weeks at the drying oven for Sunwol and Yongjin cultivars. Considering from our results, optimum harvesting time were most likely to be harvesting time of 22 days after first frost date and drying temperature of $35-40^{\circ}C$ of a weeks at the drying oven.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.1-7
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• 2016

In this research, it used cement powder and reduction slag, which generates high hydration heat in hydration reaction without heat cure below $-5^{\circ}C$ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction slag generates high hydration heat, compressive strength development is excellent. By generating highly hydration heat by $C_{12}A_7$ and $C_3A$ in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without $SO_3$, it is indicated that quick-setting occurs by shortage of $SO_3$. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, compressive strength developed 5MPa in 3 days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.97-109
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• 1973

1. The relatively lower prehardening temperature was more effective on increase of the hardiness of the intermediately hardy varieties than the higher one but either the extremely hardy or nonhardy varieties did not respond to the temperature as much as the intermediate types. 2. Five degree Centigrade was generally more favorable than $2^{\circ}C$ on hardening of the plants, especially when frozen at higher temperature for shorter duration. 3. It appears that photoperiod during prehardening and hardening did not play so important role as temperature on the hardiness. 4. The higher the soil moisture content, the higher the frost injury occurred. 5. Application of nitrogen increased markedly the hardiness and % DM of the plants. Percentage of dry matter of young seedlings might be used as an easy and rough criterion for evaluating hardiness since there was a highly significant regression of varietal frost injury on the %DM. 6. Four days appeared to be enough for hardening of plants although the plants increased gradually the hardiness as duration of hardening extended. Dehardening of the plants at relativity higher temperature took place rapidly within one to four days. 7. Under this controlled environment, freezing at about $-8^{\circ}C$ for 24 hours seemed the best for the purpose of evaluating the hardiness to low temperature. 8. It is believed that assessment of frost injury should be done at least one week after freezing. Some varieties showed strong ability to recover from the damage as recovery period was extended. 9. As a whole, Cd 80 and 83 were the most hardy and followed by Cappelle and Maris Otter. Four. winter oats varieties and Jufy I belonged to the intermediate type while the other three spring varieties were nonhardy at all. Peniarth was comparable with Maris Otter in hardiness. S 147 appeared the least hardy among the winter oats varieties. 10. It is evident that water-soluble carbohydrate content is associated with the hardiness to some extent but not primary factor involved in hardiness.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.32-37
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• 2013

Relationships among climate changes, early frost, and fruit growth were studied during the final month to harvest of late-maturing 'Fuyu' persimmon (Diospyros kaki) to assess the changes in fruit characteristics during this critical period. The heavy frost on Nov. 16 defoliated more than 70% of the leaves, but with little damage on the fruits. However, all the leaves were defoliated by the heavy frost on Nov. 20, and all the fruits were cold-damaged by $-3.3^{\circ}C$ on Nov. 21. Fruit weight increased by 8-25 g per week from Oct. 25 (142 days after full bloom) to Nov. 15, reaching to 250 g, but it decreased by 3-4 g per week after the frost. Hunter a value of fruit skin gradually increased until the last harvest on Nov. 29 with a temporary halt in early Nov. when temperature was high, whereas fruit firmness rapidly decreased after the frost on Nov. 21. Fruit soluble solids were $15.7-16.1^{\circ}Brix$ for the final month. When some branches were covered with non-woven fabrics to avoid direct contact with frost, the fruits on the branches were not visually damaged by the low temperature although 40-60% of their leaves were defoliated on Nov. 16. However, low temperature on Nov. 20 and 21 defoliated all the leaves, causing cold damage on the fruits. There was a highly significant correlation between the fruit diameter and its weight ($R^2$ = 0.73-0.91). So, the regression equations could be used to estimate weight from diameter of the fruits sampled from the branches with the non-woven fabrics. The calculated fruit weight reached to a maximum of 240 g on Nov. 15. Daily increases in fruit weight were 1.1-2.5 g from Oct. 25 to 31, 1.9-3.5 g from Oct. 31 to Nov. 7, and 1.4-1.6 g from Nov. 7 to 12. However, fruit weight decreased by 0.3-1 g per day after the cold damage on Nov. 21. The results indicate that the most appropriate harvest time could be dependent on relationship of fruit growth to climate.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.1
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• pp.11-22
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• 2010

According to IPCC 4th Assessment Report, concentration of carbon dioxide has been increasing by 30% since Industrial Revolution. Most of IPCC $CO_2$ emission scenarios estimate that the concentration will reach up to double of its present level within 100-year if the current tendency continues. The global warming has resulted in the agro-climate change over the Korean Peninsula as well. Accordingly, it is necessary to understand the future agro-climate induced by the increase of greenhouse gases in terms of the agro-climatic indices in the Korean peninsula. In this study, the future climate is simulated by an atmosphere/ocean/land surface/sea ice coupled general circulation climate model, Pusan National University Coupled General Circulation Model(hereafter, PNU CGCM), and by a regional weather prediction model, Weather Research and Forecasting Model(hereafter, WRF) for the purpose of a dynamical downscaling. The changes of the vegetable period and the crop growth period, defined as the total number of days of a year exceeding daily mean temperature of 5 and 10, respectively, have been analyzed. Our results estimate that the beginning date of vegetable and crop growth periods get earlier by 3.7 and 17 days, respectively, in spring under the $CO_2$-doubled climate. In most of the Korean peninsula, the predicted frost days in spring decrease by 10 days. Climatic production index (CPI), which closely represent the productivity of rice, tends to increase in the double $CO_2$ climate. Thus, it is suggested that the future $CO_2$ doubled climate might be favorable for crops due to the decrease of frost days in spring, and increased temperature and insolation during the heading date as we expect from the increased CPI.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.75-77
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• 2013

In this study, the characteristics of temperature history was evaluated for three hot wires with different capacity installed in slab concrete which are relatively thin. Results can be summarized as follows. First, for the case of material using 5W hot wire, all decreased to below zero at or around 24 hours. Similarly, the material using 20W hot wire decreased to 2℃ below zero at or around 80 hours but satisfied the accumulative temperature of 45° D·D at 7 days of material age. On the other hand, the case of 30W hot wire, the biggest capacity, showed the high temperature history of 5℃ in average at all areas except the corners. Thus, the target accumulative temperature was secured at or around the 3 days of material age. Considering the above, the initial damage by freezing can be prevented only if 20W or higher hot wires are used for the slabs at -10℃ of extremely low temperature environment.

• Journal of Sericultural and Entomological Science
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• v.32 no.2
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• pp.113-117
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• 1990

The recovery of mulberry from a late frost (April 24 to 27) was investigated for four varieties : Kaeryangppong, Cheongilppong, and Jamsang 21 in Cheongju area, Chungbuk Province. 1. Unfavourable meteorlogical conditions for recovery of mulberry followed the early late frost : lower than normal temperatures in mid-April, less sunshine in early and mid-Jay, lower temperatures and early and less precipitation in late-May, and less precipitation than normal in early June. 2. Jamsang 21 grew to the 2-3 leaf stage first, at which time Kaeryangppong and Jamsang 22 were at the 1-2 leaf stage, and Cheongilppong was at the swallow-bill shape-1 leaf stage. 3. The first leaf stage occurred on May 12, 15 days after the frost and, 19 days later in an average year. The difference lasted until the harvesting season, the 6 leaf stage. 4. Young shoot length was 50-58% of that in 1989. Kaeryangppong was the shortest at 50% and the Jamsang 21 highest at 58% of 1989 values. 5. Leaf number was 52-67% that in 1989. Kaeryangppong was the lowest at 52% and the Jamsang 21 highest at 67% of 1989 values. 6. Young shoot and leaf weight was 44-63%, and leaf weight 39-61%, compared to 1989. Kaeryangppong and Cheongilppong were the lowest, Jamsang 21 and Jamsang 22 were the highest, compared to 1989 data. 7. Young shoot length was 50-58% compared with 1989. Kaeryangppong was the lowest as 50%, the highest Jamsang 21 as 58%. 8. Number of leaf was 52-67% compared with 1989. Kearyangppong was the lowest as 52%, the highest Jamsang 21 as 67%. 9. Young shoot and leaf wight was 44-63%, and leaf weight was 39-61% compared with 1989. Kaeryangppong was the lowest, lowest, Jamsang 21 was the highest, Cheongilppong was similar with Kaeryangppong and Jamsang 22 was similar with Jamsang 21. 10. Rate of young shoot and leaf weight to total weight decreased from 75% in 1989 to 55-61% in 1990. Rate of laef weight to young shoot decreased from 72-82% to 67-71%, showed 5-10% decrease. 11. Leaf yield decreased highly in Jamsang 22 as 57% compared with 1989. Kearyangppong 61%, Jamsang 21 64%, Cheonglppong 72%. Leaf yield was 827kg/10g in Kaeryangppong, 1, 000-1, 050kg/10a in the other varieties.