• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.398-410
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• 1982

Summer crops grown in uplands are greatly diversified and show a large variation in difference with year and location in Korea. The principal factor for the variation is weather, in which precipitation and temperature play a leading role and such a weather factors as wind, sun lights also influence production of the summer crops. Since artificial control of weather conditions as a main stress factor for crop production is almost impossible, it must be minimized only by an improvement of cultivation techniques and crop improvement. Precipitation plays a role as one of the most important factor for production of the summer crops and it is considered in two aspects, drought and excess moisture. This country, which belongs to monsoon territory, necessarily encounter one of this stress almost every year, even though the level is different. Therefore, the facilities for both drought and excess moisture are required, but actually it is not easy to complete for them. On this account, crops tolerant to drought, excess moisture and pests should be considered for establishing summer crops. For the districts damaged habitually every season, adequate crops should be cultured and appropriate method of planting, drainage and weed control should be applied diversely. Injuries by temperature is mainly attributed to lower temperature particularly in late fall and early spring, although higher temperature often causes some damages depending upon the kind of crops. Sometimes, lower temperature in summer season playa critical role for yield reduction in the summer crops. However, certain crops are prevented to some extent from this kind of stress by improving varieties tolerant to cold, hot weather or early maturing varieties. As is often the case, control of planting time or harvesting is able to be a good management for escaping the stress. Lodging, plant diseases and pests are considered as a direct or indirect damage due to weather stress, but these are characters able to be overcome by means of crop improvement and also controlled by other suitable methods. In addition, polytical supports capable of improving constitution of agriculture into modern industry is urgently required by programming of data for the damages, establishment of damage forecasting and compensation system.

• Horticultural Science & Technology
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• v.33 no.2
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• pp.283-291
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• 2015

The aim of this study was to evaluate the changes of fruit quality, flavonoid contents and antioxidant activity of Yuzu (Citrus junos Sieb. ex Tanaka) from Go-heung and Jeju according to harvest time. Samples were harvested from August to December on the $1^{st}$ of every month. August and September samples were green colored, whereas November and December samples were yellow. The fruit shape index decreased, changing from globular to elliptical, whereas the $^{\circ}birx$ increased with ripening stage. The yuzu from Jeju was larger than that from Go-heung in each month of cultivation. August samples exhibited the highest amounts of phenolic compounds. In addition, samples from Jeju had higher total phenolic content than those from Go-heung. The content of phenolic compounds decreased with ripening until October and then increased subsequently. Antioxidant activity of the yuzu was evaluated by FRAP and DPPH methods. The antioxidant activity showed a similar trend as total phenolic content. Immature yuzu fruit was found to exhibit the highest amount of flavonoids such as naringin and hesperidin. November and December samples showed almost the same contents of flavonoids. The flavonoid content of yuzu fruit harvested from Jeju was higher than that from Go-heung. Overall, the samples harvested at the early stage, in the month of August, exhibited the highest flavonoid content, phenolic content and antioxidant activity. As the health benefits of these compounds has been demonstrated in various studies, the immature yuzu appears to be preferable for use as a raw material for formulation of pharmaceutical products as well as for functional food production after a proper in-vivo and in-vitro medical tests.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.2
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• pp.118-126
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• 2002

To evaluate the correlations of microbial populations with soil healthiness and crop production and establish the criteria for microbial population of soil types. We analyzed the microbial community structure of 13 soils which were different in physical and chemical properties and cultivation methods. According to the analysis of microbial population suing the dilution plate method, the large differences of the microbial population structures among soil types were shown: aerobic bacteria $2-27{\times}10^6$, fluorescent Pseudomonas $1-1,364{\times}10^5$, Gram negative bacteria $1-126{\times}10^4$, and mesophilic Bacillus $1-110{\times}10^5$. The density of Gram negative bacteria was highest on red pepper cultivating soils (sample no. 4 and 6) of Umsung and Gesan, Chungbuk, and the density of the fluorescent Pseudomonas was highest on greenhouse soil (sample no. 7) of Jinju, Kyungnam. The crop productivity of three soils was high as compared with those of other soils. It was supposed that the density of fluorescent Pseudomonas and mesophilic Bacillus were correlated with the incresed crop production. By MIDI analysis, 579 strains isolated from 13 soils composed of a variety of microbes including 102 isolates of Agrobacterium, 112 isolates of Bacillus, 32 isolates of Pseudomonas, 44 isolates of Kocuria, and 34 isolates of Pseudomonas. Among the 624 isolates of Gram negative bacteria, Pseudomonas including P. putida and p. fluorescens occupied the highest density (51%), and Stenotrophomonas maltophilia and Burkholderia cepacia also appeared at high density. From RAPD analysis, the fluorescent Pseudomonas strains isolated from 13 soil types showed a high level of strain diversities and were grouped into 2 - 14 patterns according to soil types. Many of unknown bacteria were recovered from the paddy soil, and needed to be further characterized on the molecular basis.

• Journal of Korean Library and Information Science Society
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• v.5
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• pp.119-168
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• 1978

This is a survey of the reserved book system in the pilot universities in Korea. We have surveyed only 22 university libraries among 29 pilot schools as of 1977, because of the differences in the library users, library organization, library facilities, and library materials between universities and colleges. In 1972, the Korean Ministry of Education developed a reformation plan for their higher education based on the teaching method of curriculum-oriented faculty instead of that of the faculty-oriented curriculum. The former puts emphasis on the cultivation of a student's thinking, creativity, and judgement through self-teaching to do a given assignment. The reserved book system in a college or university library is one of the most important methods necessary to accomplish the above educational aim. The survey used a questionnaire with 50 question on 28 items concerning the various aspects of the reserved book system in 22 pilot universities. the survey result discovered many problems needing correction. The following list describes the measures needed to correct the problems found in the pilot universities. 1. The management of a centralized reserved book system is much more effective and economical than the decentralized reserved book system when a university is located on the same campus. 2. In the university library, an independent reserved book department requires to gain the desired educational aims as compared with the reserved book room controlled by any other department in the library. 3. The reserved book system should not be adopted by all the departments at once but enlarged gradually, for it needs the understanding and support of faculty members and the university itself. 4. As competence is essential to the effective operation of the reserved book room, the university library should not place an unqualified person in charge of the reserved book department. 5. The librarian in charge of the reserved book department is required to do more professional works such as analysis of users, collection and analysis of syllabuses, maintenance of faculty member cooperation, establishment of measures to acquire unavailable materials, and drawing up an effective management plan. However, he is spending most of his time in clerical works, that is, non-professional works. 6. Three to five titles of each reserved book are considered reasonable and required materials should be shelved in proportion to the number of students, that is, one copy per eight or ten students if the materials are allowed to lend for two hours at a time. For the supplementary materials, the library needs to place two or three copies per subject. 7. Professors must select reserved books with care so that they can be used year after year. 8. Few universities are asking professors the number of class students and the date when the reserved material will no longer be needed on reserve. 9. The library should gather all the lists of reserved books from every professor at least three to five months before the courses open, because it takes a long time to obtain foreign materials. 10. It is desirable that the reserved book department should collect the lists and prepare the materials with promptness and consistency. 11. Instead of block buying, it is desirable to purchase reserved books at the time the library gets the reserved book list from the professors. The library should also inform faculty members whether it obtained each reserved book or not before the course open. 12. The library should make a copy of materials if a professor requires to reserve an out-of-print book or partial contents of a book, journal, and thesis. 13. An independent budger for reserved books from the budget for general materials is desired. 14. The shelf arrangement of reserved books by courses or professors under the same department is much more preferable than a classified arrangement. 15. While most of the universities adopted the open shelves system for all the reserved books, it is more effective and economical to take a compromise system, that is, closed shelves for requires materials and open shelves for supplementary materials. 18. Circulation of reserved books needs a different system between required materials and supplementary materials: two or three hours and/or overnight loan for the former and two and/or three days loan for the latter. 17. A reserved book room should be open a long time after class so that students can have sufficient time to use the room. 18. The library must take daily and monthly statistic as well as statistics on every aspect of the reserved book system in order that the library ma decide on policy and management of the reserved book room in collaboration with the university. Furthermore, regular reports on the use of the reserved book room should be made to the president and the executive council by the library to acquire their understanding and cooperation for the reserved book system. 19. Cooperation of faculty members is indispensable to the effective management of the reserved book department and it is desirable to make a committee which will fix various decisions about the system. Whenever the director of the library make his decision, he must consult with his staff in order to involve them earnestly in the operation of the system.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.52-59
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• 2011

BACKGROUND: This study was performed to investigate pre-harvest residue limit (PHRL) in Chwinamul, to estimate biological half-life for residue of each pesticide. Chwinamul was sprayed with pesticides of standard and double application rate. Chlorfenapyr and fenarimol were sprayed once on Chwinamul at 10 days before harvest, and it was sampled 7 times and analysed the residual change of two pesticides. METHODS AND RESULTS: Chwinamul sample was extracted with acetonitrile and partitioned with dichloromethane, and pesticide residues were determined with GCECD. Method quantitation limit (MQL) of chlorfenapyr was 0.10 mg/kg and that of fenarimol was 0.02 mg/kg. Recoveries of chlorfenapyr at two fortification levels of 1.0 and 5.0 mg/kg were $94.2{\pm}$1.70 and $99.0{\pm}1.61%$, respectively. Recoveries of fenarimol at two fortification levels of 0.2 and 1.0 mg/kg were $92.1{\pm}2.14$ and $83.1{\pm}1.98%$, respectively. CONCLUSION(s): The biological half-lives of chlorfenapyr were about 3.5 days at standard application rate, and 3.4 days at double application rate. The biological half-lives of fenarimol were about 6.0 days at standard application rate, and 5.9 days at double application rate. The PHRLs of chlorfenapyr were recommended as 13.02 and 6.25 mg/kg for 10 and 5 days before harvest, respectively. And the PHRLs of fenarimol were recommended as 2.80 and 1.67 mg/kg for 10 and 5 days before harvest, respectively.

• Korean Journal of Plant Resources
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• v.8 no.2
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• pp.201-207
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• 1995

Chinese yam (Dioscorea Opposita Thanb) has been cultivated as medicinal crop and food. The experiment was carried out to determine the effect of tuber head origin and fertilizer application method on its agronomic characters of shoot and root tuber to get some imformation on its cultivation. The tuber head cultivated were cut from normal or branched root tuber. 37-28-32-2000 : N-P-K-Humus(Kg/10a) by dispersal but 30% N reduction of Con(RN) or strip application on the two-side of hill(SRN), were applied but N and K were given by the above method with the rate of 40% in March, 30% in June and 30% in July. Agronomic characteristics related to shoot and root tuber were measured and their relationship was analyzed. Tuber head origin had no effect on emergence rate, vine length, branch and node of vine, while emergence date of the tuber head from the normal root which showed the greatest emergence rate, vine length and node in Con treatment was earlier than the others. The tuber head from the normal root, furthermore, had greater length and diameter of root tuber harvested from the field and fresh weight per plant of per 10a compared to the tuber head from the branched root, whereas in both the normal and the branched tuber head RN had the worst result in the characters related to tuber yield except tuber diameter. The tuber head from the normal root produced heavier root tuber than that from the branched tuber and SRN had the best economic yield among the application methods, which resulted from production of less branched root tubers and their rate. In both the normal and the branched tuber head, moreover, yield per plant and economic yield were positively correlated to tuber length but negatively done to number. of branch of vine.

• Korean Journal of Environmental Agriculture
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• v.35 no.2
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• pp.152-157
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• 2016

BACKGROUND: Since bottom ash (BA) contains considerable amounts of CaO and MgO, it could be a useful amendment to increase soil pH and to immobilize cadmium (Cd). This study was conducted to evaluate effect of BA application in reducing Cd phytoavailability.METHODS AND RESULTS: Bottom ash was applied at the rate of 0, 20, 40, and 80 Mg/ha to Cd contaminated soil, and then lettuce was cultivated under field condition. soil pH and net negative charge increased slightly with increasing BA application; however, there was no statistical difference among the rates. Water soluble, exchangeable+acidic, reducible, and oxidizable fraction of Cd decreased with increasing bottom ash application rate, whereas residual fraction of Cd increased with increasing bottom ash application rate. Lettuce yield increased with rate of bottom ash up to 40 kg/ha. Visual evidences of cadmium toxicity and growth inhibition were not found during lettuce cultivation.CONCLUSION: Bottom ash was effective to reduce phytoextractability of Cd and to increase lettuce yield. Conclusively, BA could be a good soil amendment to reduce Cd phytoavailability in contaminated arable soil.

• Korean Journal of Environmental Agriculture
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• v.32 no.2
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• pp.117-122
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• 2013

BACKGROUND: The scab, which is caused by Venturia nashicola, gives serious damages to pear trees. 'Niitaka' accounts for 82% of areas in pear cultivation. However 'Niitaka' is a scab susceptible cultivar. So, most of Korean farmers who growing pear trees have suffered by economic losses with the scab. In this research, we evaluated the scab resistance among elite pear seedlings to clarify genetics about the scab resistance. And we analyzed photosynthetic features with these seedlings to develop suitable cultivar which is advantageous for producing quality fruits during the growth and development of plants. METHODS AND RESULTS: We measured the rates of scab incidence among seedlings in a field experiment condition and an in-vitro test. An in-vitro test has been done with field experiment-based results. We made plant materials by grafting branches of each seedlings with 'Kongbae' rootstocks. And they had been grown for one month. Then, scab conidia suspension is sprayed to seedlings and sustained for 40 days under the controlled environment. As the results, 6 seedlings displayed lower incidence rates than other seedlings and 'Niitaka'. We also measured instant photosynthetic rates of each seedlings to determine the correlation between photosynthetic rates and fruit characteristics. However, it seemed that there is no correlation between them. CONCLUSION(S): Among the seedlings, 6 seedlings displayed the higher resistance to scab than other seedlings and 'Niitaka'. This characteristics is considered to be come from the gene expression of European pear. And we found that photosynthetic rate in trees rarely does not influence the fruit characteristics. It is considered to be affected by cultivar's own characteristics.

• Clinical and Experimental Reproductive Medicine
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• v.35 no.4
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• pp.247-265
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• 2008

Objectives: Many types of liver diseases can damage regenerative potential of mature hepatocytes, hepatic progenitor cells or oval cells. In such cases, a stem cell-based therapy can be an alternative therapeutic option. We examined whether human amnion-derived mesenchymal stem cells (HAM) and human umbilical cord-derived stem cells (HUC) could differentiate into hepatocyte-like cells as therapeutic cells for the liver diseases. Methods: HAM and HUC were isolated from the amnion and umbilical cord of the volunteers after a caesarean section with informed consent. In order to differentiate these cells into hepatocyte-like cells, cells were cultivated in hepatogenic medium using culture plates coated with fibronectin. Effects of hepatocyte growth factor, L-ascorbic acid 2-phosphate, insulin premixture fibroblast growth gactor 4, dimethylsulfoxide, oncostatin M and/or dexamethasone were examined on the hepatic differentiation. After differentiation, the cells were analyzed by RT-PCR, immunocytochemistry, immunoblotting, albumin ELISA, urea assay and periodic acid-schiffs staining. Results: Initial fibroblast-like appearance of HAM and HUC changed to a round shape during culture in the hepatogenic medium. However, in all hepatogenic conditions examined, HUC secreted more amounts of albumin or urea into medium than HAM. Expression of some of hepatocyte-specific genes increased and expression of new genes were observed in HUC following cultivation in hepatogenic medium. Results of immunocytochemistry and immunoblotting analyses demonstrated that HUC secreted albumin into the culture medium. PAS staining further demonstrated that HUC could store glycogen inside of the cells. Conclusions: Both HUC and HAM could differentiate into albumin-secreting, hepatocyte-like cells. Under the same hepatogenic conditions examined, HUC more efficiently differentiated into hepatocyte-like cells compared with the HAM. The results suggest that HUC and HAM could be used as sources of stem cells for the cell-based therapeutics such as in liver diseases.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.1
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• pp.1388-1393
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• 1968

Higher yield in rice paddies is greatly dependent on adequately balanced and timely supply of water. A majority of rice paddy in Korea is generally irrigated by rainfall, but in many cases it has to be supplemented by artificial irrigation for optimum rice culture. Although the water requirement of rice plant is far higher than that of other crops, submerged condition of rice paddy is not necessarily required. The moisture requirement of rice plant varies with its growing stages, and it is possible to increase the irrigation efficiency through reduction of water loss due to percolation in rice paddies. An experiment was conducted on the effectiveness of economical use of water by different irrigation period and different method of cultivation. The experimental plots were set up by means of randomized block design with three duplications; (a) Alltime submerged (b) Economically controlled, and (c) Extremely controlled. Three different irrigation periods were (a) Initial stage (b) Inter-stage, and (c) last stage. The topsoil of the three plots were excavated to the depth of 30cm and then compacted with clay of 6 cm thickness. Thereafter, they were piled up with the excavated top soils, leveled and cored with clay of 6cm thickeness arround footpath in order to prevent leakage. The results obtained frome the experiments are as follows; (1) There is no difference among the three experiment plots in terms of physical and chemical contditions, soil properties, and other characteristics. (2) Colulm length and ear length are not affected by different irrigation methdos. (3) There is no difference in the mature rate and grain weight of rice for the three plots. (4) The control plot which was irrigated every three days shows an increased yield over the all the time submerged plot by 17 persent. (5) The clay lined plot whose water holding capacity was held days long, needs only to be irrigated every 7 days. (6) The clay lined plot showes an increased yield over the untreated plot; over all the time submerged plot by 18 percent, extremely controlled plot by 18 percent, and economically controled plot by 33 percent.