• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.118-127
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• 1985

The grain temperature is a crucial factor determining the deterioration rate of stored grain. Therefore, it is used to be predicted in order to evaluate the various stored methods rapidly and inexpensively. In this study, a mathematical model was developed to simulate the temperatures of grain stored in a cylinderical bin. It was formulated for the two dimensional heat transfer by the finite difference method. Then, it was verified statistically using the actual test deta and the predicted. The changes of grain temperature were analyed using the simulated data of one year for a safe stoarge and the following results were obtained: 1. Simulation model developed by the finite difference method was validated with the actual and the predicted grain temperatures and it's result showed that it could predict the grain temperature of storage bin reasonably well. 2. Grain temperature near the wall of storage bin were changed with $6-7^{\circ}C$ higher then average atmospheric temperature from June to September. Therefore, the parts of stored grain near the wall is supposed to be deteriorated fast. 3. When the dimension of bin diameter is about the same as the bed height, the changes of grain temperature of radial direction was higher than the verticals. 4. The predicted temperature showed that the grain temperature of which were from the end of April to mid October were higher than the safe storage limit at Yusung, Korea.

• Journal of Korean Society of Forest Science
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• v.104 no.1
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• pp.50-59
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• 2015

We investigated seasonal variation in photosynthetic characteristics and chlorophyll content of the Loranthus tanakae, Viscum album var. coloratum and its hosts in Korea. The maximum photosynthesis and transpiration rate of L. tanakae were $9.36{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at $941{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PAR (photosynthetically active radiation) in June, $5.06{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at $1,596{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PAR in July, respectively. The maximum photosynthesis and transpiration rate of V. album var. coloratum were $6.51{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at $418{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PAR in Autumn, $3.91{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ at $1,735{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PAR in Autumn, respectively. V. album var. coloratum was able to conduct photosynthesis in November whereas its host and L. tanakae were not able to conduct photosynthesis. Especially transpiration rate of L. tanakae were always higher than its host and V. album var. coloratum. The chlorophyll a+b contents of L. tanakae was $8.23mg{\cdot}g^{-1}$ in July, V. album var. coloratum was $10.27mg{\cdot}g^{-1}$ in June, and chlorophyll a/b ratio of L. tanakae was 1.7~3.7, V. album var. coloratum was 1.1~4.5, depend on season.

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.183-190
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• 1986

Identification of fruit sucking moths, their larval host plant, and degree of damages to fruits were investigated in $1982{\sim}'83$ at two orchards in Cheonnam province. In this study, 4 families 30 species were collected as fruit sucking moths and among them 10 species are newly recorded in Korea as fruit sucking moth: Catocala electa(B.), Spirama helicina(H.), Erebus ephesperis(H.), Parallelia stuposa(F.), Simplicia niphona(B.), Marumba gaschkewitschii(B. et G.), Agrius convolvuli(L.), Thyatira batis (L.), and Spilosoma niveum(M.). Larval host plants of fruit sucking moths in the vicinity of the fruit orchard include Cocculus trilobus D., Albizzia julibrissin D., Pterocarya rhoifolia S., Jaglans mandshurica M., Solanum melongena L., Brassia campestris S., Rubus idaeus C., Thalictrum aquilegifol L., and Rhus succedanea L. As the damage on different varieties of the main fruit trees, plum was orderly Santa Rosa>Beauty, Apple was Chook>Hong Og, Peach was Choseng Baeg Do>Hwang Do>Baeg Do, and Grape was Campbell Early>Neo Mascat>Golden Queen. Seasonal occurrence of main fruit sucking moth Spirama retorta(C.) showed peak 3 times in early-July, late-July, early-September. Oraesia emerginata(F.) showed peak 3 times in late-July, early-August, early- September and Lagoptera juno(D.) showed peak only in late-July and Adrias tyrannus amurensis(S.) showed peak only in mid-July. Fruit sucking moths were immigrated from p.m. 6 to a.m. 2, with peak in p.m. 10 to p.m. 12.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.336-343
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• 2019

Wet direct-seeding (WDS) is an important method for improving the competitiveness of rice production in South Korea. We analyzed the optimum direct-seeding date to establish the rice standing rate in each area and selected suitable areas for WHS by considering the heading stage limit date for improving cultivation safety. As a result, the rice direct-seeding date to control weedy rice was around 5.15, 5.17-5.19, and after 5.20 in southern Youngnam, southern Honam, and the Middle Coast areas, respectively. However, the optimum seeding date for good standing rice was in late March in most areas. Analyzing by area, most of the southern plains and parts of the central inland plain are suitable for WHS. However, most parts of Gwangwon-do, and the northern parts of Chungbuk, Gyeongbuk, and Yeonghonam areas are not suitable for WHS, and should therefore avoid WHS.

• Applied Biological Chemistry
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• v.40 no.5
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• pp.416-421
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• 1997

Physicochemical properties of six cultivars of Cheju citrus fruits were investigated according to the harvest date. The fruit index of Citrus. unshiu Marc. var. miynawa, C. $natsudaidai{\;}H_{AYATA}$ and C. sudachi ranged from 1.14 to 1.38 with oval form. The fruit index of C. grandis OSEECK, C. aurantiun LINN and C. platymamma. Hort. SWINGLE ranged from 0.89 to 1.03 with a round form. The fruit weight showed the heaviest in C. grandis, followed by C. natsudaidai, C. aurantiun, C. unshiu, C. platymamma and C. sudachi. The rate of flesh showed the highest in C. unshiu, followed by C. platymamma, C. nat녀daidai, C. sudachi, C. grandis and C. aurantiun. The ratio of juice showed the highest in C. unshiu, followed by C. sudachi, C. platymamma., C. natsudaidai,, C. grandis, C. aurantiun. C. unshiu and C. platymamma, which showed a possibility to be used as raw materials for juices. The soluble solid and the Brix/acid ratio of all the varieties increased as the fruits ripen. Especially those of C. unshiu and C. platymamma were high(10.39, 7.67) in full ripe compared to other varieties. Acid content of C. natsudaidai, C. aurantiun, C. grandis and C. sudachi was sustained higher than $3{\sim}5%$ from the middle of September to the middle of January, and there was the possibility of manufacturing aromatic products like citrus vinegar. The C. sudachi contained the highest content of vitamin C,77.48 mg/100 g. The correlation between vitamin C extraction and season was insignificant. Rind and color value of all varieties were investigated, and the value of the L, a and b increased as the fruits were ripen. The value of a of rind of C. $natsudaidai{\;}H_{AYATA}$ and C. grandis until the end of November was negative. This means that their color was not presented by November since the chlorophyll was in the rind, unlike the colors of the rind of C. unshiu, C. sudachi and C. platymamma which were completed by that time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.419-427
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• 2021

In South Korea, direct seeding of rapeseed (Brassica napus L.) is difficult during spring cultivation in early March because of the low yield production associated with late flowering and poor seed quality. To compare the period of direct sowing, the present study investigated the growth characteristics of rapeseed according to planting dates. Specifically, 35 day-old seedlings were transplanted or directly sown on four different dates (late February, early March, late March, and early April) in 2020 and 2021. As the planting date was delayed, the days to flowering of rapeseed decreased. Similarly, the plant height, seed set percentage, and seed yield of rapeseed were reduced upon delay in planting. The seed yield of rapeseed through direct seeding in late February was the highest, 2.76 ton·ha^-1. On all seeding dates, except for late February, the transplanted rapeseed produced a higher yields than the directly seeded rapeseed. The crude oil and oleic acid content, which is related to the quality of rapeseed, decreased with the delay in planting dates, and this decrease was greater, with the direct seeding of rapeseed depending on the sowing time. In the correlation analysis, the planting date was significantly and negatively correlated with the yield, crude oil content, and oleic acid content of the transplanted rapeseed, while the sowing date was negatively correlated with the plant height, silique size, yield, and seed quality of the directly seeded rapeseed. Finally, the effect of planting date on rapeseed growth was stronger in direct seeding than in transplanting. Therefore, during spring cultivation after late February to early March, transplanting, rather than direct seeding, in more advantageous in terms of seed quality and yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.1
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• pp.17-26
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• 2022

Rice is one of the three major grains globally, and has been used as a staple food in Asian countries for a long time. In recent years, with the increase in the use of processed rice, the development and distribution of rice flour varieties have become a research focus. However, rice flour varieties are susceptible to pre-harvest sprouting (PHS). In this study, the optimal transplanting date for rice flour varieties for maximum yield production with PHS avoidance was examined. Four rice flour varieties with different maturity types (early maturing type, Garumi2 and medium-late maturing type, Seolgaeng, Hangaru, and Singil) were selected. The field experiment was conducted in Chuncheon (Central Plain area) and Cheorwon (Northern Plain area), Gangwon Province, Republic of Korea, from 2017 to 2019. The transplanting dates used were May 10, May 20, May 30, June 10, and June 20 in Chuncheon and April 30, May 10, May 20, May 30, and June 10 in Cheorwon. In Chuncheon, late transplantation decreased PHS in Garumi2. In Cheorwon, PHS in Garumi2 decreased with transplantation dates after May 20. The PHS decreased in Seolgaeng, Hangaru, and Singil with late transplantation in Chuncheon and Cheorwon. The optimal transplanting date for maximum yield production while avoiding PHS for Garumi2 was estimated to be June 10 in Chuncheon and May 25 in Cheorwon; for Seolgaeng, the optimal transplanting dates were May 20 in Chuncheon and May 15 in Cheorwon; for Hangaru, it was estimated to be May 30 in Chuncheon and May 15 in Cheorwon; and for Singil, the optimal dates were May 25 in Chuncheon and May 15 in Cheorwon.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.2
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• pp.79-88
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• 2022

This study was conducted to evaluate the productivity of whole crop silage wheat utilizing the paddy fields during a couple of years from 2019 to 2021 in Suwon, Korea. This investigation was used the two maturity types of wheat cultivar 'Cheongwoo' (early) and 'Taeu' (late). The heading date of 2^nd year (Oct. 2020 to May. 2021) cultivation was delayed about 11 to 13 days by more than 1^st year (Oct. 2019 to May. 2020). The growth characteristics were shown that the plant height was increased in 2^nd cultivation, while the number of culms and the panicle part ratio were decreased. Moreover, the nutritive value of 'Cheongwoo' and 'Taeu' were also decreased in 2^nd cultivation. These changes have thought to a difference of the precipitation by cultivation years. Because, the precipitation during the period from the end of winter dormancy to the harvesting stage in 2^nd (337 mm) cultivation was more about twice than 1st (169.3 mm) cultivation. However, the dry matter yield of 'Cheongwoo' was not shown a statistical difference by cultivation years, while 'Taeu' was shown to decrease tendency. The total dry matter yield regardless of the cultivation years were higher in 'Cheongwoo' than 'Taeu', and especially 'Cheongwoo' was more 3 tons per hectare (15.3 t/ha) than 'Taeu' (12.6 t/ha) at 2^nd cultivation (p<0.01). The trend of dry weight in 'Cheongwoo', early mature type, showed a relatively high ratio of dry matter (p<0.05) was considered that due to a high panicle ratio by a fast heading and an adequate weight of panicles by a sufficient maturing. In conclusion, selecting the early maturity cultivars could achieve a higher and more stable total dry matter yield considering the cropping system in the central region. Furthermore, it also has the advantage of being able to double-cropping system with forage rice, which has considered the maximum whole-crop forage production year-round. These results suggest that the 'Cheongwoo' be optimum cultivar to produce the year-round forage on paddy fields in the central region.

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.281-289
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• 2022

The effect of five different constant temperatures (18, 21, 24, 27, and 30±1℃) and a photoperiod of 14 : 10 (L :D) h on the reproduction parameters of Spodoptera frugiperda was studied. The longevity of adult female S. frugiperda decreased with increasing temperature (22.4 days at 21℃ and 13.9 days at 30℃) but not at 18℃. The pre-oviposition period and oviposition period was the shortest at 30℃ compared to the other temperatures. The total fecundity egg count was 887.4, 1,246.4, 1,348.9, 1,154.9, and 1,034.2 at 18, 21, 24, 27 and 30℃, respectively, during its life span. The survival rate of female S. frugiperda decreased rapidly after 13 days at 18℃, after 14 days at 21℃, after 15 days at 27℃, and after 9 days at 24℃, and 30℃. On the third day after the start of oviposition, 50% of the total fecundity was accomplished. In corn fields at less than the 10-leaf stage, the distribution of S. frugiperda egg masses was observed in the middle and lower plant regions, corresponding to 46.8% and 41.4% of the total egg masses, respectively. Egg masses were mostly found on the underside of the leaf blade (abaxial) of corn(66.7%). After releasing S. frugiperda adults on May 12, May 17, May 25, and May 30, the number of eggs per egg mass was 89.9, 88.5, 126.6, and 127.9, respectively. Egg masses of the subsequent generations of S. frugiperda were observed from late June, and the number of eggs per egg mass was 155.8 in late June, 270.7 in early July, and 303.5 in mid-July.

• Journal of Korean Society of Forest Science
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• v.62 no.1
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• pp.24-42
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• 1983

To develop Ilex cornuta which grow naturally in the southwest seaside district as new ornamental tree, the author chose I. cornuta growing in the four natural communities and those cultivated in Kwangju city as a sample, and investigated its ecology, morphology and characteristics. The results obtained was summarized as follows; 1) The natural distribution of I. cornuta marks $35^{\circ}$43'N and $126^{\circ}$44'E in the southwestern part of Korea and $33^{\circ}$20'N and $126^{\circ}$15'E in Jejoo island. This area has the following necessary conditions for Ilex cornuta: the annual average temperature is above $12^{\circ}C$, the coldness index below $-12.7^{\circ}C$, annual average relative humidity 75-80%, and the number of snow-covering days is 20-25 days, situated within 20km of from coastline and within, 100m above sea level and mainly at the foot of the mountain facing the southeast. 2) The vegetation in I. cornuta community can be divided that upper layer is composed of Pinus thunbergii and P. densiflora, middle layer of Eurya japonica var. montana, Ilex cornuta and Vaccinium bracteatum, and the ground vegetation is composed of Carex lanceolata and Arundinella hirta var. ciliare. The community has high species diversity which indicates it is at the stage of development. Although I. cornuta is a species of the southern type of temperate zone where coniferous tree or broad leaved, evergreen trees grow together, it occasionally grows in the subtropical zone. 3) Parent rock is gneiss or rhyolite etc., and soil is acidic (about pH 4.5-5.0) and the content of available phosphorus is low. 4) At maturity, the height growth averaged $10.48{\pm}0.23cm$ a year and the diameter growth 0.43 cm a year, and the annual ring was not clear. Mean leaf-number was 11.34. There are a significant positive correlation between twig-elongation and leaf-number. 5) One-year-old seedling grows up to 10.66 cm (max. 18.2 cm, min. 4.0 cm) in shoot-height, with its leaf number 12.1 (max. 18, min), its basal diameter 2.24 mm (max. 4.0 mm, min. 1.0 mm) and shows rhythmical growth in high temperature period. There were significant positive correlations between stalk-height and leaf-number, between stalk-height and basal-diameter, and between number and basal diameter. 6) The flowering time ranged from the end of April to the beginning of May, and the flower has tetra-merouscorella and corymb of yellowish green. It has a bisexual flower and dioecism with a sexual ratio 1:1. 7) The fruit, after fertilization, grows 0.87 cm long (0.61-1.31 cm) and 0.8 cm wide (0.62-1.05 cm) by the beginning of May. Fruits begin to turn red and continue to ripen until the end of October or the beginning of November and remain unfading until the end of following May. With the partial change in color of dark-brown at the beginning of the June fruits begin to fall, bur some remain even after three years. 8) The seed acquision ratio is 24.7% by weight, and the number of grains per fruit averages 3.9 and the seed weight per liter is 114.2 gram, while the average weight of 1,000 seeds is 24.56 grams. 9) Seeds after complete removal of sarcocarp, were buried under ground in a fixed temperature and humidity and they began to develop root in October, a year later and germinated in the next April. Under sunlight or drought, however, the dormant state may be continued.