• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.121-131
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• 2008

This study was conducted to delineate temporal and spatial patterns of potential risk of cold injury by combining the short-term cold hardiness of Campbell Early grapevine and the IPCC projected climate winter season minimum temperature at a landscape scale. Gridded data sets of daily maximum and minimum temperature with a 270m cell spacing ("High Definition Digital Temperature Map", HD-DTM) were prepared for the current climatological normal year (1971-2000) based on observations at the 56 Korea Meteorological Administration (KMA) stations using a geospatial interpolation scheme for correcting land surface effects (e.g., land use, topography, and elevation). The same procedure was applied to the official temperature projection dataset covering South Korea (under the auspices of the IPCC-SRES A2 and A1B scenarios) for 2071-2100. The dormancy depth model was run with the gridded datasets to estimate the geographical pattern of any changes in the short-term cold hardiness of Campbell Early across South Korea for the current and future normal years (1971-2000 and 2071-2100). We combined this result with the projected mean annual minimum temperature for each period to obtain the potential risk of cold injury. Results showed that both the land areas with the normal cold-hardiness (-150 and below for dormancy depth) and those with the sub-threshold temperature for freezing damage ($-15^{\circ}C$ and below) will decrease in 2071-2100, reducing the freezing risk. Although more land area will encounter less risk in the future, the land area with higher risk (>70%) will expand from 14% at the current normal year to 23 (A1B) ${\sim}5%$ (A2) in the future. Our method can be applied to other deciduous fruit trees for delineating geographical shift of cold-hardiness zone under the projected climate change in the future, thereby providing valuable information for adaptation strategy in fruit industry.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.359-367
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• 2023

Grapes are one of the most important fruit trees both domestically and globally. Recently, changes in plant phenology and frequent low temperatures due to climate change are increasing the possibility of damage to grape shoots in spring, which is a serious threat to grape production. This study was conducted to investigated the severity of shoots damage and the change of free sugar content in the plant organs by phenological stage, especially, from germination to leafing period. Furthermore, in order to compare the cold hardiness among grape varieties including 'Campbell Early', 'Kyoho' and 'Shine Muscat' widely grown in Korea, lethal temperature (LT₅₀) and free sugar content by grape variety were analyzed. Shoot damage by low temperatures continued to increase as the phenological stage progressed gradually, from the bud burst to the fourth leafing stage. On the other hand, the free sugar content of each organ except leaves continued to decrease, showing pattern to similar to cold hardiness. This indicates a close relationship between free sugar content and cold hardiness. In terms of cold hardiness comparison among grape varieties, 'Shine Muscat' showed the highest cold resistance in the leafing stage with the lowest LT₅₀ and the highest total free sugar content. Next was 'Kyoho' and 'Campbell Early'. There are clear differences in cold hardiness depending on the variety. However, it is not the same at all growth stage. It may change according to phenological stage and influenced by free sugar content at that time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.119-124
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• 2006

This study was carried out at the Chuncheon Substation, National Institute of Crop Science to determine the effect of cold water irrigation on the milling and polished quality of rice, as well as its physicochemical and amylogram characteristics, and palatability Chilling by Irrigation of cold water $(17^{\circ}C)$ induced delay of days to heading, reduction of culm length, inferiority of panicle exsertion and high sterility of panicle. Head rice ratio was decreased, while the percentage of chalky and creak rice increased with increasing sterility over from 20%. Protein content was gained 0.9-2.0% more than, while whiteness and palatability of the milled grain were reduced under cold water irrigation treatment. Significant decrease in maximum viscosity and breakdown viscosity of rice flour was investigated under cold water treatment by amylogram analysis, while the initial gelatinization temperature and setback viscosity were increased. Sensory panel test showed that the palatability of cooked rice was unfavorable and its stickiness was lower compared with that under normal condition. Differences in the aroma of cold-treated and untreated cooked rice were not performed significantly.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.255-261
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• 2016

The present study was conducted to characterize physiological responses of aerial part according to soil water stresses in 'Mihong' peach trees. Discolorations, wilting and falling of leaves were observed in chronological order as response for waterlogging and no irrigation and the phenomena started from basal to end of shoots. Shoot growth in elongation and thickness decreased and fallen leaves were severe in waterlogged trees. Function of water uptake by roots and photosynthesis and leaf respiration decreased by waterlogging. Leaf chlorophyll contents decreased in both treatments. In waterlogging treatment, decrease of chlorophyll was observed in normal leaves with waterlogging using light microscopy. Starch content was lower in both treatment and carbohydrate content was lower in root with waterlogging. These results demonstrated that waterlogging weakened the function of soil water uptake and movement and decreased photosynthesis and fallen leaves. Finally the peach trees would wither or suffer low temperature damage through the shortage of reserve accumulations. We suggested that waterlogging damage in peach trees could be reduced to take notice of irrigation and install drainage facility to improve soil condition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.1
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• pp.84-90
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• 1986

An experiment was conducted to know the effects of planting dates (March 5, 15, and 25 and April 4) and transparent polyethylene (P.E.) film treatments(tunnel, tunnel slit, and mulch) on air and soil temperatures and growth and yield of a sweet corn variety, Great Bell. Maximum air and soil temperatures and minimum air and soil temperatures were greater at tunnel>tunnel slit>mulch in that order. Differences in maximum air and soil temperatures among the P.E. film treatments were much greater than those in minimum air and soil temperatures. However, when film was opened due to high air temperature over 40$^{\circ}C$ in the tunnel, air temperature was similar but soil temperature was lower com-pared to mulch. High temperature stress could be avoided in tunnel slit without opening film by increase in the number of slits. Cold damage of corn seedlings was avoided by tunnel and reduced by tunnel slit, and frost-damaged seedlings under the mulch were recovered in few days. The number of days from planting to silking was reduced as planting date delayed. At early plantings, tunnel enhanced early growth and silking, but it delayed at late plantings because tunnel was opened during the most of day time due to high temperature. Black streaked dwarf virus(BSDV) disease was more severe at early plantings and it was reduced in tunnel slit at late plantings because plants were grown under the film at the time of infection. The number of marketable ears was similar among all treatments except mulch at March 5 planting where BSDV was severely infected. Gross income was high in tunnel and tunnel slit at March 25 planting which had more larger marketbale ears and tunnel and tunnel slit at March 5 planting which had higher market price.

• Journal of the Korean Geographical Society
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• v.43 no.1
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• pp.20-35
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• 2008

This study used crop data from statistics yearbooks in Naju and climate data from Gwangju weather station to investigate whether climate changes have had significant impact on crops. The sample crops are rice, barley, pear, radish, Korean cabbage and red pepper. The results showed that the changes in temperature have shifted crop phonology and affected crop growth. The rice and barley heading date were advancing and had negative correlation with average temperature over 30days before average heading date. The number of rice grains per unit area $(m^2)$ were decreasing while the number of barley grains per unit area $(m^2)$ were increasing because average temperature during grain filling period of rice (barley) was increasing (decreasing). Therefore, decreasing (increasing) yields of rice (barley) can be predicted by global warming. The sprouting, flowering and full flowering date of pear were advancing. The sprouting date of pear had negative correlation with average temperature from February to March and the flowering and full flowering date of pear had negative correlation with average temperature from February to April. The brix and weight of pear were increased and were most sensitive to August and September average temperature. An earlier blossom of pear trees holds the danger of damage by late frosts. The plant length of radish and chinese cabbage were decreasing and negatively influenced by maximum temperature on September. The fruit set numbers of red pepper were increasing recently and had positive correlation with minimum temperature on August. The growth of radish and Korean cabbage will be poor, but the growth of red pepper will be good by rising temperature.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.159-164
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• 2001

This study were conducted to investigate the influence of chilling on photosynthetic rate, root activity, contents of total sugars and fatty acids of cucumber seedlings grown in a greenhouse. Even though photosynthetic activity of seedlings exposed to $0^{\circ}C$ for 5 hours was little or insignificantly influenced, it was reduced by 52.8% and 67.7% in seedlings exposed to the same temperature for an extended 10 and 24 hours, respectively. Photosynthetic rate decreased significantly when seedlings were illuminated, as compared to continuously held under darkness, during 15 hours of chilling treatment at 3$^{\circ}C$. Recovery of photosynthetic ability was also retarded by illumination during a recovery period after chilling treatment. Root activity, as measured by the oxidation power of $\alpha$-naphtylamine, was significantly reduced by chilling treatment at 0 to 6$^{\circ}C$, but amount of bleeding xylem sap collected at 40 days after chilling treatment was not significantly different among treatments. Total sugar content increased by 12 and 23% as compared to the control in seedlings chilled for 24 hours, respectively, at 3$^{\circ}C$. Contents of unsaturated linolenic and oleic acids increased, while content of saturated palmitic acid decreased with chilling treatment.

• Journal of the KSME
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• v.44 no.1
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• pp.27-27
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• 2004

미국 국방부 소속 육군차량사업부(National A Automotive Center)는 대체에너지를 이용한 군용 차량 개발을 위해 Michigan 주 Rochester Hills에 위치한 E Energy Conversion Devices(ECD) 사와 일부 기술 개발 에 대한 기술 제휴를 한다고 발표했다. 국방부는 태양전 지와 수소를 연료로 사용하는 대체에너지 차량을 개발하 기 위해 ECD에 1단계 연구에 필요한 연구비를 지원했다. 이번 연구에는 연료전지를사용한차량개발을위해 5 500,$\omega$0달러가 투자되는데, Texaco Ovollic Hydrogen S Systems(TOHC)의 고체 휴대용 수소 연료와 채충천 (refueling) 시스탬이 주요 개발 목표로 설정됐다. ECD의 역할은 최근 개발된 Toyota Prius에 시범 적으로 장착된 저압 고체형 수소 저장 시스템의 기술을 군용 차량에 알맞게 전환시키는 것이다. TOHC와 ECD가 개발한 고체형 수소 보관 시스댐은 고압을 요구하는 연료전지 차량의 수소 저 장 시스템이 갖고 있는 많은 문제점들을 해결할 수 있을 것으로 기대되는 연료전지를 이용한 엔진 개발 중 최신 기술이다. 특히 전투 상황에서 차량이 폭발하기 쉬운 수소 저장 탱크를 장착한 채 전 장으로간다는 것은적에게 노출 될 경우자살과마찬가지인 치명적인 피해를 입을수 있다. 이 프로젝트의 개요를 살펴보면, 수소 저장 시스템은 적어도 약 lOkg의 수소를 적은 용적 내에 낮은 압력에서 안전하게 고체 상태로 저장할 수 있다. 이 고체 저장 용기는 하루에 두 번 1.7kg의 수소를 10분 이내에 재급유할 수 있다. 수소는대부분고압가스형태나저온액체 형태로보관된다. 기체나액체 형태의 수소는 연료전 지에 사용되기에는 적합하지 않은 점이 많다. Ovonie 수소 저장 방법은 수소를 저압 고체 형태 ( (metal hydride)로 보관하는 방법으로, 고압 기체나 저온 액체가 갖고 있는 많은 문제점들을 해결 할수있다. 그림을 참조하면 고체 형태의 수소 보관 방법이 다른 보관 방법에 비교해 단위 체적당 최고 6배 많은수소질량을보관할수 있다. 이 고체 형태의 보관방법은수소가적절한합금과평형 압력 이 상의 환경에 놓일 경우 합금에 홉착되는 현상을 이용하고 있다. 수소를 흡수한 합금은 새로운 특성 을 가진 metal hydride로 변하게 된다. 이 과정 에서 열이 부산물로 발생한다. 반대로 수소를 metal hydride로부터 분리시키기 위해서는 합금을 가열해야 한다.

• Fire Science and Engineering
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• v.13 no.3
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• pp.19-26
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• 1999

$CO_2$ extinguishing system is the most $\phi$pular among the gas extinguishing system. $CO_2$ is usually stored with liquified state. But, it gasifies at the tip of nozzle when $CO_2$ was released through the pipe and head. A ro$\alpha$n temperature is very low when $CO_2$ was released. So electrical instrument, magnetic storage equipment and memory semiconductor are electrically or physically injured by cooling effect in a few minutes. So, we intend to find out temperature profile and electrical damage in compartment area, and supply basic d data for research and making standards and code through the full scale experiment. As result of experiment on the damage due to cooling effect from $CO_2$ extinguishing system, i instantaneous discharging temperature. was $-82.5^{\circ}C$ in average. An average temp. in the compartment after discharging $CO_2$ was $-40^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.447-451
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• 2003

When sowing green peas in the autumn, proper seedling stands and growth quantity should be secured before winter begins. Also, for proper acclimatization, injuries caused by low temperatures, frost or high temperatures in the P.E. film during mulching, should be avoided during the regeneration period; that being early spring. The days required for growth in each stage in Yeosu are shorter than those in Naju because Yeosu has high temperatures during the growth period. Furthermore, in Yoesu, it was observed that there were more effective branches as well as effective and attached node positions on the branches. The first pods on the main stems and effective branches were observed to be higher than those in Naju. The number of pods per plant and the number of seeds per pod in Yoesu was greater than for those in Naju and the pod length was longer as well. Considering the missing plant rate, growth, and green pod yield, the optimum sowing date for the green pea was mid-November in both location. The stable acclimatizing date for the green pea was early March when the highest yield can be acquired due to a lot of effective branches and pods per plant and with the lowest missing plant rate and rate of injury in acclimatization.