• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.562-568
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• 1995

Changes in rice yield and soil chemistry of dry seeded rice in double cropping of rice and barley were investigated at National Yeongnam Agricultural Experiment Station during 5 years (1990-1994). Barley straw added or removed dry seeding had safe rice seedling stand for good rice production. However, the coefficient of variation of seedling stand by year was higher than dry seeding in rice single crop. Rice seedling height was slightly reduced by barley straw incorporation. However, it recovered soon as rice growing progressed. Heading time delayed 4 days in flat seeding method but not in high-ridged seeding method which imply that. this is more safe seeding technology than flat seeding method. Comparing to rice single crop, barley straw added dry seeding increased rice yield by 2∼19%(Average of 5 years: 8%) from second year due to higher panicle and spikelet number. Contents of organic matter was 2.71% in 1990. In 1994, it decreased 2.61% for rice single crop, while increased 3.02% and 3.41% for barley straw removed or added field, respectively. Rice grain quality was not significantly different among cropping patterns.

• Korean Journal of Medicinal Crop Science
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• v.5 no.2
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• pp.95-101
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• 1997

This study was conducted to investigate how a labor saving for conventional hand sowing and respond to major agronomic traits under different planting density in 1993 and 1994. Each trial was a randomized block split plot with row spacing as the main plots and hill spacing as subplots. Sowing rate appeared lower in 20 or 25cm hill spacing using machine seeder than in hand sowing. Sowing time required reduced more 121 hours per hectare in 60cm row, 20cm hill spacings using machine seeder than in hand sowing. Increasing row and hill spacings reduced number of seedling stand per unit $area(m^2)$. Both number of pods per plant and grain weight per plant and showed highly increase in wide planting. Best yield obtained in 60cm row, 20cm hill spacing using machine seeder. Accumulative mean air temperature was positively correlated with stem height, number of pods per plant and yield, otherwise accumulative rainfall was negatively correlated with ones. A highly significant negative correlation was showed between number of seedling stand per unit $area(m^2)$ and number of branches, number of pods per plant, grain weight per plant and yield. Yield was positively correlated with number of branches, number of pods per plant and grain weight per plant.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.12-19
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• 1998

The pattern of rice cultivation in Korea is changing from hand transplanting and machine transplanting into direct-seeding for low input and cost-down practices. However, there are still some obstacles to establish the direct-seeding cultural practices because of poor seedling stand, lodging, and weed infestation. In particular, there were much more and wide weed occurrence in direct-seeding rice as compared with the transplanted rice. Weed occurrence in terms of dry weight of weeds was highest in dry direct-seeded rice followed by sowing an puddled soil, sowing on submerged soil in order as compared with transplanting with infant rice seedling. Echinochloa crux-galli was a common dominant weed with 35~44% distribution in any direct-seeding methods. The dominant weed species were E. crux-galli, Cyperus difformis, C. serotinus, and Ludwigia prostrata in dry-seeded rice. The dominant weed species in water-seeded rice were E. crus-galli, Eleocharis kuroguwai, Scirpus juncoides, and Monochoria vaginalis. Yield loss of rice due to weeds at weedy condition was 96% in dry direct-seeded rice. In water-seeded rice, yield loss was 61%, whereas yield loss was 40% in machine transplanting with infant rice seedling.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.353-358
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• 2008

The purpose of this study was to examine the effects of black polyethylene film mulching and soil conditioners on the growth, yield, and flavonoids biosynthesis of mungbeans. The seedling stand rate, plant height, and pods per plant were 98%, 61 cm, and 15.1, respectively, when the mungbean grown black polyethylene film mulches. They were greater than these results when the without mulches was applied by 13%, 9 cm, and 1.8, respectively. Mungbean grown with black polyethylene film mulches ($243\;kg{\cdot}10a^{-1}$) exhibited 38% more seed yield than without mulches ($176\;kg{\cdot}10a^{-1}$). However, no significant difference in contents of vitexin and isovitexin of mungbeans between with black polyethylene film mulches and without mulches was observed. Among soil conditioners, standard fertilizer+oil cake and standard fertilizer+mineral powders increased number of pods. The standard fertilizer+oil cake showed the highest seed yield (119%) of mungbean when it mixed with standard fertilizers, and followed by mineral powders (115%). The mixed combinations of oil cake or mineral powders also seem to have affected the biosynthesis of vitexin and isovitexin, whose content in mungbeans was significantly more.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.1
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• pp.14-21
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• 1997

This experiment was conducted to identify the growth and yield differences in rice cultural types: Broadcasting on flooded paddy surface(BF), drilling on flooded paddy surface(DF), puddled-soil drill seeding(PD), drill seeding on dried paddy flat(DD), and machine transplanting of lO-day old seedling(MT) at National Honam Agricultural Experiment Station in 1995. Among the cultural types of direct seeding, the number of seedling stand showed high in order of DD>BF>DF>PD. Tillering at early growth stage was faster in MT and effective tiller showed higher in MT than in direct seeding. Growth duration from seeding to heading was longer in direct seeding than in MT for 2-13 days of Dongjinbyeo and 10-18 days of Nonganbyeo. Root distribution ratio at the surface soil revealed high in order of BF>DF>PD>DD and MT. Culm wall thickness of 4th internode was thicker in machine transplanting of 10-day old seedling than in direct seeding, and the depth of buried culm showed deep by turns of MT> DD>PD>DF and BF. The height of center gravity and moment related to lodging revealed higher in direct seeding than machine transplanting that resulted high lodging index by turns of BF>DF>DD> PD among the direct seeding cultural type. Lodging was occured seriously in the order of BF>DF>PD>DD =MT in Dongjinbyeo but wasn't significantly different in Nonganbyeo among the cultural type. The yield components and grain yield showed varietal differences but was not significantly different between in MT and in direct seeding, and among cultural types of direct seeding.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.2
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• pp.272-279
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• 1983

Canopy structure and light interception were investigated as related to forage growth and dry matter production in four swards; pure orchardgrass, pure ladino clover, orchard-ladino mixture, and multi-mixture that was consisted of four grasses and three legumes. In spring, multi-mixture stand had the highest LAI, while ladino clover pure stand had low LAI but the highest leaf volume density(L$_{v}$ ). In fall, both pure orchardgrass and orchard-ladino mixture had higher LAI and L$_{v}$ than others. Orchard pure stand was an electophile canopy with K, light extinction coefficient, of 0.29-0.43, pure ladino clover a planophile canopy with K of 0.72, and both mixtures a plagiophile canopy with K of 0.43-0.58. Dry matter yields had highly significant correlation with LAI in all stands. Optimum LAI for pure orchardgrass was estimated above 6.0 and for pure ladino clover, orchard-ladino mixture and multi-mixture were about 3.8,5.0 and 8.0, respectively. Conclusion was made that multi-mixture and orchard-ladino mixture had better canopy structure to improve light penetration and forage yield than pure stands.

• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.197-205
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• 2013

In this study, we developed a program of optimizing stand-level carbon stock using a stand-level yield model and the Simulated Annealing (SA) heuristic method to derive a optimized forest treatment solution. The SA is one of the heuristic algorithms that can provide a desirable management solution when dealing with various management purposes. The SA heuristic algorithm applied 'thermal equilibrium test', a thresholds approach to solve the phenomenon that does not find an optimum solution and stays at a local optimum value during the process. We conducted a sensitivity test for the temperature reduction rate, the major parameter of the thermal equilibrium test, to analyze its influence on the objective function value and the total iteration of the optimization process. Using the developed program, three scenarios were compared: a common treatment in forestry (baseline), the optimized solution of maximizing the amount of harvest(alternative 1), and the optimized solution of maximizing the amount of carbon stocks(alternative 2). As the results, we found that the alternative 1 showed provide acceptable solutions for the objectives. From the sensitivity test, we found that the objective function value and the total iteration of the process can be significantly influenced by the temperature reduction rate. The developed program will be practically used for optimizing stand-level carbon stock and developing optimized treatment solutions.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.479-488
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• 1995

Relationships between pine-mushroom(Tricholoma matsutake) yield and important climatic factors for the yield(such as monthly precipitation, relative humidity, temperature, and radiation percentage) were examined to find out limiting factors for pine-mushroom production and to develop a method for overcoming the factors by analyzing the yield and climate data for 17 years collected from 18 main regions of pine-mushroom production. Although there were variations among the production regions, climatic condition of September was the most significant factor for pine-mushroom yield in general, and the degrees of importance of each climatic factors were different among the production regions. Mean minimum temperature of September was positively correlated with pine-mushroom yield($$r^2{\geq_-}0.41$$) at the 1% level, of which were 9 regions such as Youngduck, Uljin, Samchuck, Bongwha arid so on. In these regions, vegetation control was expected to be effective for pine-mushroom production by allowing much sunlight penetration to the pine stand, which may increase soil temperature and keeping the temperature around the fungal colony in soil. Precipitation during September was positively correlated with pine-mushroom yield($$r^2{\geq_-}0.41$$) at Namwon, Moonkyung and Sangju. Thus, irrigation around fungal colony in dry soil during September would be effective for enhancing mushroom yield at the regions. Pine-mushroom yield of 1994 was quite low, similar to that of 1993, due to serious drought. In this period, we could manifest the possibility of enhancing pine-mushroom yield by irrigation for overcoming drought at Moonkyung and Keochang regions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.3
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• pp.260-264
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• 2009

Sufficient seedling establishment of Chinese milk vetch (CMV) is the most important factor in the CMV cultivation. In order to obtain sufficient seedling stand, CMV seed should be planted at right seed planting date. An optimum CMV seed planting time for stable seedling establishment was determined based on the final water drainage time for rice harvest in fall. Five planting times from 10 days before water drainage (DBWD) to 15 days after water drainage (DAWD) at five day interval were evaluated during the period of 2006-2007 and 2007-2008 and the optimum CMV seed planting time was determined based on seedling stand, winter survival rate, and dry matter production. CMV seedling stand before winter was high with $575{\sim}1,050\;plants/m^2$ regardless of seed planting times but after overwintering, it was greater in seed planting date between 5 DBWD to 5 DAWD than that of 10 to 15 DAWD treatments. Winter survival rate, dry matter production and seed production yield also showed similar trend to the seedling establishment. On the other hand, when CMV seeds were sowed early at 10 DBWD, seedling stand and winter survival rate were lower than that of 5 DBWD to 5 DAWD. This result indicates that an optimum CMV seed planting time based on the final water drainage could be between 5 DBWD (September 20) to 5 DAWD (September 30).

• Journal of Korea Foundry Society
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• v.24 no.4
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• pp.231-237
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• 2004

Bake hardenable steel utilizes the phenomenon of strain aging to provide an increase in the yield strength of formed components. An increase of the carbon content will improve the bake hardening response: more solutes are available to pin mobile dislocations and to form the clusters more rapidly. But aging resistance decrease as increasing solute carbon. In order to under-stand the compatibility between bake hardenability and aging resistance. The optimum solute carbon control methods during manufacture should be determined. In this paper, the effect of continuous heat cycle conditions such as soaking temperature, rapid cooling start temperature, cooling rate on BH(Bake Hardenability), AI(Aging Index), YP-El(Yield Point Elongation) and other mechanical properties have been investigated. and following results were obtained. In the case of soaking temperature, BH increases with higher soaking temperature because of NbC $dissolution(830^{\circ}C)$, Therefore the solute carbon and BH at $850^{\circ}C$ and $870^{\circ}C$ are higher than these at $810^{\circ}C$. But BH at $870^{\circ}C$ is a little lower than that at $850^{\circ}C$ owing to the ferrite grain size. The measurement of amount of dissolution C using IFT(Internal Friction Test) can explain the relation of solute carbon and BH.