• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.13-20
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• 1979

High purity alumina has been extracted form low grade Korean alunite. Alunite ore was treated by 15% $NH_4OH$ solution, followed by 10% $H_2SO_4$ leaching and metallic impurities such as Fe and Ti were removed by solvent extraction method. Alumina prepared by the extraction process was 99.9% in purity. Hot Petroleum Drying Method has been employed for the preparation of uniformly fine alumina powder, using chemical reagent aluminum sulfate and ammonium aluminum sulfate extrated from Korea alunite. The sinterability of alumina powder prepared by Hot Petroleum Drying Method was shown to be improved in comparison with the one treated by other methods such as ball milling method, but dry pressing was difficult due to the agglomeration of calcined powder. The best slip of alumina powder prepared by Hot Petroleum Drying Method contained a lower soild content than the one treated by other methods. The alumina body formed by soild and drain casting with the former alumina powder showed a higher sintered density.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.149-150
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• 2001

A fish feed being used most widely in aquacultural farm is a moist pellet (MP) feed which has been being prepared by mixing of commercial dry feed and nutritional oil to raw fish ky. The two major problems in the use of MP feed is to be readily dispersed in water of an aquacultural farm, and to cause lipid oxidation and bacteria infection during storage. The former induce an environmental pollution of the farm and the latter lower nutritional values and develop fish diseasees. (omitted)

• Journal of the Speleological Society of Korea
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• v.45 no.46
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• pp.49-67
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• 1996

After the opening of Gosu - cave, as tourist has increased, the inner parts and outer regions of cave is changed. This paper focuses on the environmental changes according to development of tourist resort in Gosu-cave. The result of this study can be found in the following facts: (1) As cave is opened lighting equipments set up for the purpose of helping inspection and coming in and out. (2) As the temperature rises in the coming in and out of tourist, this is caused to dry and peel off the topographes in cave. (3) The quality of water in cave is contaminated by the wastes, garbages and coins by tourists. (4) As Chungju - Dam has constructed, the linkages of the other tourist resort of Gosu - cave is improved. It is raised on the accessability of Gosu - cave. (5) As people has access to Gosu - cave, tourists increased more than the former times. Thus this phenomenon is contributed to the increasements of regional incomes and opportunity of regional employment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.409-416
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• 1987

The object of this study was to investigate the differences in dry matter production, physiological characteristic and grain yield of soybean (Glycine max (L.) Merr.) as affected by planting dates in southern region of Korea. This experiment was conducted using four planting dates and four varieties over 3 years (1982-1984). The different responses of soybean varieties to different temperature and daylength, days from planting to flowering were ranged from 43 to 55 days when planted on May 10 long daylength and low temperature condition. Flowering duration was ranged from 12 to 27 days and 9 to 13 days for the plantings made on May 10 and July 9, respectively. Therefore, it was the shortest under the short daylength and high tempera-ture condition. It also appeared that the later planting caused the lower dry matter weight and leaf area index which resulted in lower grain yield. But grain yield was not directly correlated with the unbalance of Xink/Source Ratio and the lodging from excessive vegatative growth. The grain yield was the highest in May 30 and the lowest in July 9 planting: it was ranged from 2.26 to 2.55 t/ha in the former and 0.85 to 1.20 t/ha in the latter, respectively. The increase in yield was depended on the increase in the number of pods per plant, the number of seeds per pod and the seed weight. The distribution ratio of dry matter to leaves was the hightest at the sixth trifoliolate leaf stage and gradually declined thereafter in all planting dates, and it also appeared that the later planting, the lower the ratio of dry matter to leaves.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.274-282
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• 1992

Annual forage crops have been increasingly important for conpensating insufficient forage production of perennial pastures took place for short interval. This experiment was conducted to determine the effect of sward composition and NㆍP fertilization on forage production and intercompetition of subterranean clover-Italian ryegrass and berseem clover-Italian ryegrass. The two clovers were grown in the field at the clover/ryegrass ratios of 0/100, 25/75, 50/50, 75/25 and 100/0 where no, N (200 kg /ha), P (50 kg /ha) or NㆍP fertilization was done. Each crop was separated after harvest and drying. Relative Crowding Coefficient (RCC), aggressivity and Relative Yield Total (RYT) were analyzed on the basis of the harvested dry matter of each crop. Berseem clover-ryegrass mixtures produced greater yield than subclover-ryegrass mixtures as a result of higher yields of the two component species. In the former forage yield was increased with increased rate of clover up to 75%, while in the latter the highest yields were obtained at more than 50% of the clover. In the mixtures N stimulated the growth of ryegrass, whereas P did only that of subclover. The two clovers produced more forage than the companion grass under no and only P fertilization although the reverse result was true under N or NㆍP fertilization, but the annual forage yield was decreased in the order of N and P, N, P, and no fertilization. The mixture yields were overyielded compared to the Expected Yield. Although generally RCCs and RYTs of subclover were higher than those of berseem clover in the mixtures differing the composition rate or under no and only P fertilization, those of the former clover were lower under N or NㆍP fertilization. In the clover-ryegrass mixtures, ryegrass acted as an aggressor and became more aggressive under P fertilization.

• The korean journal of orthodontics
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• v.24 no.2
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• pp.447-476
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• 1994

This study was performed to evaluate the initial reaction of maxillofacial complex to the Class II intermaxillary and the anterior vertical elastic forces on the six types of archwires including multiloop edgewise arch wires(MEAW). A human dry skull was used for this purpose and this investigation was done by holographic interferometry. Based on such investigation, the fringe pattern and the number of fringes of each condition were compared and analyzed. The findings of this study were as follows: 1. As the orthodontic forces increased, the amount of displacement increased. 2. As the orthodontic forces were applied, the fringes were shown not only in the teeth and the maxilla but also in the adjacent bones, i.e., temporal bone, zygomatic bone, nasal bone, frontal bone and sphenoid bone. And the direction of fringe pattern and the number of fringes were different from each other by the sutures. 3. As the long Class II elastic forces were applied, the backward-downward displacements of the anterior teeth and the maxilla were shown, and backward displacement of the former were grater than those of the latter. And backward displacements were greater by the long Class II elastic forces than by the short Class II elastic forces. 4. As the anterior vertical elastic forces were applied, downward displacements of the anterior teeth and the maxilla were shown, and the downward displacements of the former were greater than those of the latter relatively. 5. The downward displacements of the anterior area to the anterior vertical elastic forces of the MEAW were greater than those of other archwires. In addition, the more tip-back bend was applied, the more displacement was seen. 6. As the Class II intermaxillary forces and the enough anterior vertical elastic forces were applied on the MEAW with tip-back bend, there was an intrusive effect of the posterior teeth.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.5 s.112
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• pp.69-82
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• 2005

These studies were carried out (1) to investigate the growth characteristics of Sedum album L. in the field, (2) to propose a suitable shallow peen roof system for this plant, and (3) to evaluate plant growth in the proposed system over the long term. The growth characteristics, such as morphological properties, growth habit, shade tolerance, and flowering, were surveyed. In experimental shallow green-roof systems, the effects of drainage type, substrate type, and soil depth on plant growth were investigated. Then drought tolerance was investigated. After planting Sedum album L. in the proposed system survival rate, cover, and resistance to insects, heal and cold were evaluated for about 2 years. The results of these studies are summarized below. 1. In the field, the aboveground part of Sedum album L. did not die back during the winter. Plant height was 4$\sim$7 cm. Roots were distributed to a depth of 5$\sim$7 cm. Sedum album L. is a compact ground-cover plant that spreads vigorously. Shading condition of less than $30\%$ of full sunlight didn't cause any trouble, but shading conditions above $87\%$ made the shape of the shoots and leaves abnormal. The plant bloomed from June to August and had a rather large compound umbel of white, star-shaped flowers. 2. Two systems, a drainage-blend-10 cm soil depth and a reservoir$\cdot$drainage-blend-15 cm soil depth, performed best in terms of cover, fresh weight, and dry weight. The first has an advantage for green roofs because it is lighter than the latter. 3. In drainage-blend-10 m soil depth and modified reservoir · drainage-blend-10 cm soil depth system no plants died for about 4 months after stopping the irrigation. The visual quality of the latter system was above 5 for 4 months and that of the former was under 5 after 2 months. In the field, however, the drought tolerance of Sedum album L. grown in the former would be enough to withstand the dry season. Considering the urban ecosystem and the importance of healthy growth the modified reservoir $\cdot$ drainage-blend-10 cm soil depth system was finally recommended. This system was composed of a 4 cm thick drainage layer and drain outlets placed at a height of 2.5 cm. 4. In the proposed system, the survival rate was $100\%$, and there was no injury induced by insects and heat. The leaf density decreased a little in winter. Cover increased throughout the year. Sedum album L. was planted with a cover of 72$cm^{2}$ on 3 April 2003; on 16 June 2003 and 15 June 2004, cover was $132.66\pm$5.87 $cm^{2}$(1.8 times) and $886.98\pm$63.51 $cm^{2}$(12.3 times), respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.4
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• pp.280-286
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• 2016

This study was conducted to evaluate the growth characteristics and dry matter yields of Italian ryegrass (Lolium multiflorum Lam., IRG) cultivars for three years (2011~2013). The cold-resistance of domestic cultivars was stronger than other foreign varieties. Among early-maturing cultivars, dry matter (DM) yield of 'Kowinearly' was significantly higher (8,751 kg/ha) than other cultivars (p<0.05). In medium-maturing cultivars, DM yield of 'Kowinmaster' and 'Tam 90' was 9,394 and 7,461 kg/ha, respectively. Of the two, the former's DM yield was higher than the latter's (p<0.05). Among late-maturing cultivars, DM yield of 'Hwasan 104' (9,809 kg/ha) was similar to 'Hwasan 101' (9,354 kg/ha), but significantly higher than the other late-maturing cultivars (p<0.05). According to the results obtained from present study, early-maturing cultivars with cold-tolerance and high productivity is required for the paddy field cultivation of an Italian ryegrass cultivar after rice harvest in Cheonan region. Medium- and late-maturing cultivars are more advantageous for the dry field cultivation of the maximum quantity that is possible. In conclusion, to select which cultivar/s to grow, the climate of the growing area, weather conditions, and the cropping system must all be considered.

• Korean Journal of Food Science and Technology
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• v.5 no.4
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• pp.231-234
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• 1973

Dried lavers, Porphyra yezoensis Ueda, were stored at $20^{\circ}C$ for 10, 25 and 45 days under a dry and humid conditions respectively, and changes in the contents of organic acids were studied by GLC and supplementary use of GC-MS. 1) Out of eight acids determined, i. e., pyruvic, lactic, oxalic, malonic, fumaric, succinic, malic, and citric acid, relatively abundant ones were oxalic, succinic, malic, and citric acid. 2) Oxalic, malic, and succinic acid did not show any notable changes in their contents under a dry condition, however, under a humid condition the contents of the former tow acids decreased rapidly showing contrast to that of succinic acid, of which content increased markedly. The content of citric acid rapidly· decreased independent of the storage conditions. 3) Among some unidentified components, two of them were presumed to be aromatic acids from their mass spectra. The contents of the two acids decreased slowly under a dry condition, however, rapidly decreased under a humid condition and after 45 days storage almost all of them disappeared. 4) The contents of total volatile acids were increased under the both storage conditions, however, the rate of increment was larger under a humid than under a dry condition.

• Plant Resources
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• v.4 no.1
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• pp.6-12
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• 2001

Growth and yield of licorice were investigated under the different conditions of ridge height, planting density, and irrigation in order to establish its cultural practices for the domestic production with the aim to substitute the import. Seedlings were grown under low ridge(20cm) and high ridge(40cm) in low density plot(60$\times$30cm) and high density plot(40$\times$30cm), respectively. The low ridge cultivation of large seedlings increased plant height and root length under low density, and stem and root diameter under high density compared to the high ridge cultivation. In the high ridge cultivation, high density plot was 1.1 to 1.3 times in plant height, root length, stem and root diameter as high as low density one. Fresh and dry weight of plant and root in high ridge were 1.3 to 1.5 times as high as those in low one. The growth of small seedlings(4~10g) were generally poor compared to that of large seedlings. High density plot in low ridge showed the good growth characteristics including plant height, root length, stem and root diameter, and number of branch. High density plot was 1.4 to 1.6 times in fresh and dry weight of plant and root as high as low density plot. In the seasonal changes of growth under various irrigation regimes, the twice irrigation a day produced the more number of leaf than the other regimes since around 46 days after transplanting. The former irrigation resulted in 1.2 to 1.4 times in plant height as long as the other irrigations around 26 days after transplanting and then the difference was increased to 1.6 to 2.0 times around 64 days after transplanting. Under the twice irrigation a day, plant height, root length, stem diameter, root diameter, number of leaf, fresh plant weight, dry plant weight, fresh root weight, dry root weight were 1.6 to 2.0, 1.1, 1.2 to 1.6, 1.3 to 1.8, 1.9 to 2.7, 1.7 to 8.0, 1.6 to 2.8,2.0 to 3.0, 1.6 to 2.7 times as high as those under the other irrigation regimes, respectively.