• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.241-241
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• 2017

Sweet potatoes (Ipomoea batatas (L.) LAMK.,) have been cultivated in Central and South America for about 2000 years and are now grown mainly in Asia and South America. Sweet potatoes are annual in the temperate region, but are classified as perennial in the tropical region. In 2000, the cultivation area of sweet potatoes decreased to about 16,000 ha in 2000, but the cultivation area increased slightly in recent 20,000 ha in Korea. Sweet potatoes do not show higher maximum dry matter production of 120 ~ 150g per plant, and the leaf area index (LAI), which maximizes dry matter production, is known as 3.0 ~ 4.0. As the leaf area increase, the penetration of light into the canopy becomes poor, and sufficient photosynthesis cannot be achieved in the lower leaves, on the other hand the respiration increase, which results in poor dry matter production. This study was conducted to know the responses of sweet potatoes to intensive shading treatment of 80% shading. This experiment was conducted for about 42 days from September 6, 2016 to October 18, 2016 at Gyeongsang National University Experimental Farm, Jinju, Korea. The plant canopy was shaded with black nylon 80% shade cloth suspended 1.2 m above the ground. The photosynthetic rate, stomatal conductance, chlorophyll fluorescence, SPAD and NDVI were measured in 3 replicates every 7 days after shading initiation. After the fresh weight was measured, the samples were dried at $80^{\circ}C$ in a dry oven and measured. By the 80% shading treatment, chlorophyll fluorescence of the treated plants was slightly higher than that of the control, the SPAD value was higher by 3.4 and NDVI value was higher by 0.01. However, photosynthetic rate and stomatal conductance were lower than those of the control. The stomatal conductance of the control were two times higher than those of the control and the photosynthetic rate of the control was four times higher than that of the control. In control, plant showed a tendency to steadily increase in fresh weight and dry weight. However, in the case of shading treatment, the tendency to increase in the fresh and dry weight of tuberous roots was not clear. The fresh weight of shoot showed a tendency to increase steadily while the difference between treatment and control was not large, but tended to decrease after frost.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.280-280
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• 2017

In Korea, the average air temperature has been elevated twice faster than the average global warming. And the climate warming is characterized by the smaller rise of air temperature in summer and the greater rise of air temperature in spring and winter. Therefore, the number of frost-free days to determine the cultivation ability of crops has increased by more than 15 days in 10 years according to climate warming. This climate warming trend has extended and is projected to extend not only the sweet potato growing season but also the sweet potato early cultivating area to higher altitude and latitude region. This study was carried out to evaluate the possibility of sweet potato double cropping in the southern island area of Korea by assessing the growth and yield performance of sweet potato cultivated at extremely-early and -late time. We had performed at Yokji Island Yokji Island($E128^{\circ}$ 18' $N34^{\circ}$ 36'), a representative specified complex area of sweet potato cultivation in southern Korea. As the test varieties, the major cultivars of the this region, Shinyulmi and early hypertrophic cultivars, Dahomi were used. The prior cropping were planted with PE film mulching on March 30 and April 10, and harvested after 110 days. So the succeeding cropping were planted without PE film mulching on July 25 and August 5 according to the harvesting time of the prior sweet potato and harvested after 120 days. As a control, it was harvested on September 15, 120 days after planted on May 15. Each experimental plot had an area of 12 square meters consisting of 4 beds, and was planted one at a time at intervals of 25cm. We had investigated growth characteristics - main vine length, node number, branch number, total vine yield, and tuberous root characteristics - tuberous root number, average weight, starch value, and etc. After harvesting, we analyzed the economic effects by examining the postharvest quantity, the input labor, the management cost, and the income. The total yield of marketable products in prior and succeeding cropping was 46~70% higher than that of control. The average unit price of sweet potato was 36% higher than the conventional culture, and the gross income increased by 98%, but the operating cost increased by 83%, and the farm income increased by 103%. There are considerations such as the difficulty of enlargement of cultivation area due to lack of labor in limited space and the need for watering measures due to spring drought. However, if the area of application for sweet potatoes double system is increased by 10%, it can be used as a new cropping system.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.295-299
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• 2007

Resistance to chestnut gall wasp (Dryocosmus kuriphilus) of Korean prevailing chestnut cultivars, new cultivars released by Korea Forest Research Institute (KFRI), and local cultivars by growers was investigated to select optimal cultivars suitable for main chestnut producing areas. During three years investigated from 2004 to 2006, we could find no damage by chestnut gall wasp in any cultivars of test sites located in Gongju and Chungju of the central area. However, most cultivars of Gwangyang, Sancheong and Hapcheon sites located in the southern area showed a lot of damage by chestnut gall wasp. Hapcheon was most severe in comparison with regional damage by chestnut gall wasp. From comparison among cultivars, Kwangeun, Sandae, Eunsan and Idae released by KFRI showed no damage suggesting the highest resistant cultivars. On the contrary, over 20% in total damage by chestnut gall wasp was investigated in Tanzawa, Riheiguri, Kurakata-amaguri, Pyeonggi, Gwangdeok, Seil, Sinipyeong and Yumabyuni suggesting susceptible cultivars. In damage by chestnut gall wasp according to investigated position within tree, weak shoot was more severe than bearing shoot. Damage by chestnut gall wasp of major cultivars in Gwangyang, Sancheong and Hapcheon sites was remarkably decreased in 2006, and it seems to be caused by biological control by natural enemies such as Torymus sinensis.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.6
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• pp.97-109
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• 2008

This study first attempted to catch the transformational affairs and motives of the representative pavilion, Hanbyeok in Honam after its construction. Especially, it re-illuminated the morphologic, significant and functional change process of a pavilion after the early Joseon Dynasty by taking the local scenery, Hanbyeokdang as a sample, and considering the space and scenic characteristics, and diachronically understood its creation process and rebuilt its inherent positional meaning to reach the following conclusion. 1. Weoldanglu, at its early foundation, seems to have stressed the function of a private banquet and lecture hall to train younger students, and served as a reception space. Then the reception function gradually increased, and up to before 1530, it seems to have been called Weoldanglu(月塘樓) or Weoldangwon(月塘院). 2. In 1619, Governor Yoo Saek changed the pavilion name to Hanbyeokdang through the subject of a poem. 200 years after Weoldang's death, it became a public space called Hanbyeokdang, an amusement place in which scholars cultivated great morale, and participated in the sending-off and welcoming of predecessors and successors. This seems to have taken a foothold as a public event or entertainment space for the local administration, Jeonjuboo(全州府) through the remodeling process sponsored by the public. 3. Scenic language such as its indicating name, expression type and surrounding view through old map and so on, the shape of Hanbyeokdang evolved and changed to diverse types after the foundation of Weoldanglu, at the heart of which Hanbyeokdang with its two legs standing at a rock was located. 4. During the late 18th century, Hanbyeokdang seems to have been a wing corridor connected closely to the left corridor of the Jeonju stream bed, whose pattern is presumed to have existed even during the early 19308. Such changes in scenic language make us assume that diverse auxiliary space, a wing corridor, was erected for use as a public banquet and amusement spot of Jeonjuboo Castle, the inherent function of Hanbyeokdang after the mid 18th century. 5. Penetration of Hanbyeokgool and the erection of Hanbyeokgyo caused the change of the ancient shape of Hanbyeokdang. Specifically, a great Hanbyeokgyo passing by the pavilion changed the relative scale, so the pavilion image of pursuing unity with nature has lost the old inherent refinement and visual character.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.1
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• pp.70-74
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• 2015

An LED plant factory farm is an alternative way to grow crops regardless of weather, season, and blight in such times of climate change. In recent years, it is a currently active and vibrant research field. The industry, which ranges from leaf vegetables to high value products, is expanding. This study was conducted to test tthe response of LED (Light-emitting diode) irradiation on the growth characteristics and ginsenoside levels indoors, in order to find out suitable light conditions. Ginseng seedling was transplanted from a styrofoam pot ($L{\times}W{\times}D$:$495{\times}315{\times}215mm$, inside diameter) into a closed plant production system in four blue LED (BL) and red LED (RL) different ratios of 1:1, 1;2, 1:3, 1:4 in a temperature range of $20{\sim}25^{\circ}C$, relative humidity of between 55 and 65%, and a 12-hour photoperiod. The LED irradiation shows the highest levels were found at 1:1 of BL and RL ratio at $61.21{\mu}mol\;s^{-l}m^{-2}$, 1:2 ratio $68.55{\mu}mol\;s^{-l}m^{-2}$, 1:3 ratio $63.85{\mu}mol\;s^{-l}m^{-2}$ and 1:4 ratio $62.41{\mu}mol\;s^{-l}m^{-2}$ from highest to lowest respectively. After analyzing from shoot and root 2 yers old ginseng plant which were cultivated under 1:3 irradiation of BL and RL ratio, it generally showed a positive effect under a 1:3 ratio of BL and RL.

• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.332-337
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• 2004

A suspected biotype of Scirpus planiculmis to be resistant to sulfonylurea(SU) herbicides was identified in Seosan reclaimed paddy fields in Korea, in 2004. The fields have been cultivated for monocultural rice production with wet-direct seeding method and continuously treated with SU-based herbicide mixtures for thirteen years since 1990. In greenhouse studies, 6 different SU herbicides, such as azimsulfuron, bensulfuron-methyl, cinosulfuron, ethoxysulfuron imazosulfuron and pyrazosulfuron-ethyl, completely controlled the Musan assession of Scirpus planiculmis at the recommended dose of each herbicide, however, the Seosan accession of S. planiculmis biotype was survived 20 to 45% even treated with 5 times higher dose of each recommended rate of all herbicides treated. The $GR_{50}$ values of 6 SU herbicides for Seosan accession of S. planiculmis were 47 to 100 times higher than those for Musan accession of S. planiculmis. The $I_{50}$ values pyrazosulfuron-ethyl to acetolactate synthase(ALS) extracted from Sesan and Muan accession of S. planiculmis were 409 nM and 0.8 nM, respectively. The $I_{50}$ value of Seosan was 511 times higher than that of Muan accession. These results suggested that the Seosan accession of S. planiculmis have strong resistant characteristics to 6 SU herbicides, respectively, indicating that resistance might be due to the alteration in the target site of ALS.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.129-134
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• 2002

194 plantlets regenerated from leaf explants of boxthorn 'Cheonyang' were cultivated to investigate their morphological characteristics in the field for 2 years. Based on the morphology of leaves, 66.1% of them had elliptical type leaf, the same as that of mother plants, while 22.2% in oval type, 7.2% in obovate type, 2.6% in long-obvate type and 2.1% in lanceolate type. They were classified to 4 groups; group A was selected with both high fruit size and fruit yield, group B with only high fruit size, group C with larger or thicken leaf, and group D with multiple brenches. In comparision of production efficiency between the selected groups and mother plants, group A (99741, 99781, 99854, 99870 and 99886) were longer (2.1 to 2.7 mm) in length of fruits and higher in fruit production (15 to 30%) as compared to mother plants. Croup D (99797 and 99892) was higher in leaf production (7.2%) as compared to boxthorn 'CL1-48', which is the highest in leaf production among boxthorn veriaties.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.179-186
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• 2014

The objective of this study was to determine the best performing switchgrass (Panicumvirgatum L.) cultivar with three different seeding dates as a bioenergy source in Republic of Korea. Split-plot in time with three replications was performed and three switchgrass cultivars, Carthage (CT), Cave-in-Rock (CIR), and Forestburg (FB) were used in this experiment from 2009 to 2012. Plots were seeded on April 23, May 4, and May 13, 2009 and were harvested once in November each year. No fertilizer was applied to the field for the first year; however, in second and third years (June 2010 and May 2011, respectively), N, $P_2O_5$ and K2O fertilizers were applied in 67,45 and 90 kg $ha^{-1}$, respectively. Soil pH (5.9) and climate condition including temperature ($10.4{\sim}17.5^{\circ}C$) and precipitation (89.4~109.8 mm $month^{-1}$) were suitable for switchgrass cultivation. Total dry matter yields were higher in CT and CIR compared to FB and were 16.9, 15.9, and 4.5 ton $ha^{-1}$, for CT, CIR, and FB, respectively (p<0.0001). The samples were analyzed for dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude fiber (CF), ether extract (EE), and ash. No significant differences in energy content (p = 0.96) and chemical composition among cultivars (p>0.05) were found. Seeding dates did not affect DM yield (ton $ha^{-1}$), chemical composition and energy content significantly (p>0.05). Significant difference was observed for heights among CT, CIR, and FB (177.59, 169.98, and 94.89 cm, respectively, p = 0.0002). In conclusion, based on soil characteristics and climate condition in Korea compared to other countries, switchgrass can be cultivated successfully. Considering dry matter yield and energy content of these three cultivars of switchgrass CT and CIR adapted better to climate in Middle Eastern of Republic of Korea than Forestburg for bioenergy purpose.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.2
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• pp.79-83
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• 2009

In this study, actual state of operation of rotary tillage was surveyed in the central part of Korea which includes 29 rural community around Asan city, Choongnam principal. 29 heads of the village and 44 farmers were surveyed at the field with a questionnaire on the operation of rotary tillage with farm tractors. Power requirement of rotary tillage operation was measured at the field of each farmers during rotary tilling operation in the central part of Korea. Summaries of this study are summarized as follows. 1) Operations of tillage and land preparation were found to be carried out with farm tractors by 98 percents which are results of the survey on 29 heads of the village and 44 farmers. 2) More than half of the farms had tractors with horsepower more than 38 kW which states that most tractors were supplied in middle and large size. 3) The case of applying secondary tillage after the first primary tillage were 79 percent among the most of operations of tillage and field preparation. Rotary tillage were carried out on the most of wet paddy fields and only 14 percent of dry fields were cultivated with rotary tillage. 4) 63.6 percent of farm tractors were surveyed to meet the recommended field capacity on tillage operation by the government which were ranged from 15.1 to 34.9 ha. And the field capacity of these farm tractors were greater than that of annual total area of operation field, 13.2ha (data from Information of agricultural machinery, National agricultural products quality service, Korea), which states the utilization of agricultural machinery was high in the area surveyed. 5) 46 percent of farmers changed the blade of rotary implement when they used it over the field capacity of rotary blade of 33 ha which is the area of field for rotary operation per a blade change. 55 percent of farmers changed the rotary blade more than once per two years. 6) The required power for rotary operation of each farm tractors were measured as 17.206 kW at untilled paddy field and 34.989 kW at untilled dry field on the average, respectively. The required power for rotary operation was measured as 28.248 kW on the average at the paddy field which had been plowed once and 28.015 at the paddy field that had rotary tillage operation. Untilled dry field showed the highest value of the required power for rotary operation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.166-174
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• 2018

Potato(Solanum tuberosum L.) is one of the major food crop in the world following rice, wheat, and maize. It is thus important to project yield predict of potato under climate change conditions for assessment of food security. A crop growth modelling is widely used to simulate crop growth condition and total yield of various crops under a given climate condition. The decision support system for agrotechnology transfer (DSSAT) cropping system model, which was developed by U.S. which package integrating several models of 27 different crops, have been used to project crop yield for the impact assessment of climate change on crop production. In this study, we simulated potato yield using RCP 8.5 climate change scenario data, as inputs to the DSSAT model in five regions of Korea. The genetic coefficients of potato cultivar for 'superior', which is one of the most widely cultivated potato variety in Korea were determined. The GenCalc program, which is a submodule of the DSSAT package, was used to determine the genetic coefficients for the superior cultivar. The values of genetic coefficients were validated using results of 39 experiments performed over seven years in five regions. As a case study, the potato yield was projected that total yields of potato across five regions would increase by 26% in 2050s but decrease by 17% in 2090s, compared with 2010s. These results suggested that the needs for cultivation and irrigation technologies would be considerably large for planning and implementation of climate change adaptation for potato production in Korea.