• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.24.1-24.9
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• 2020

Objectives: It is known that bioactive materials interact with the dentin to undergo biomineralization. The exact role of moisture in this interaction is unknown. Here, we investigate the effects of dentin moisture conditions on the dislocation resistance of two bioactive root canal sealers (MTA Fillapex [Angelus Solucoes Odontologicas] and GuttaFlow BioSeal [Colténe/Whaledent AG]) at 3 weeks and 3 months after obturation. Materials and Methods: Mandibular premolars (n = 120) were prepared and randomly divided into 3 groups based on the dentin condition: group 1, dry dentin; group 2, moist dentin; group 3, wet dentin. Each group was divided into 2 subgroups for root canal filling: MTA Fillapex and GuttaFlow BioSeal. Dislocation resistance was evaluated by measuring the push-out bond strength at 3 weeks and 3 months. Failure modes were examined under a stereomicroscope. Data were statistically analyzed by Kruskal-Wallis test with a significance level of 5%. Results: Moist dentin resulted in higher bond strength values for both materials at both time points. This was significantly higher than wet and dry dentin for both the sealers at the 3 months (p < 0.05), while at 3 weeks it was significant only for GuttaFlow Bioseal. The different moisture conditions demonstrated similar trends in their effects on the dislocation resistance of the 2 root canal sealers. Conclusions: The dentin moisture conditions had a significant impact on its interaction with the bioactive materials tested. Maintaining moist dentin, but not dry or wet dentin, may be advantageous before the filling root canals with bioactive sealers.

• Restorative Dentistry and Endodontics
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• 제49권2호
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• pp.20.1-20.13
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• 2024

Objectives: This study investigated the nanoleakage of root canal obturations using calcium silicate-based sealer according to different drying methods. Materials and Methods: Fifty-two extracted mandibular premolars with a single root canal and straight root were selected for this study. After canal preparation with a nickel-titanium rotary file system, the specimens were randomly divided into 4 groups according to canal drying methods (1: complete drying, 2: blot drying/distilled water, 3: blot drying/NaOCl, 4: aspiration only). The root canals were obturated using a single-cone filling technique with a calcium silicate-based sealer. Nanoleakage was evaluated using a nanoflow device after 24 hours, 1 week, and 1 month. Data were collected twice per second at the nanoscale and measured in nanoliters per second. Data were statistically analyzed using the Kruskal-Wallis and Mann-Whitney U-tests (p < 0.05). Results: The mean flow rate measured after 24 hours showed the highest value among the time periods in all groups. However, the difference in the flow rate between 1 week and 1 month was not significant. The mean flow rate of the complete drying group was the highest at all time points. After 1 month, the mean flow rate in the blot drying group and the aspiration group was not significantly different. Conclusions: Within the limitations of this study, the canal drying method had a significant effect on leakage and sealing ability in root canal obturations using a calcium silicate-based sealer. Thus, a proper drying procedure is critical in endodontic treatment.

• Journal of Forest and Environmental Science
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• 제32권4호
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• pp.353-366
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• 2016

The effect of different environmental conditions and altitudes on the growth and reproductive characteristics in 12 teak plantations at 4 different blocks (Cauvery canal bank, Topslip and Parambikulam (Tamil Nadu), Nilambur and Wayanad (Kerala) of Southern India was investigated. The annual rainfall and mean monthly temperature of the study areas varied significantly from 1390 to 3188 mm and 16 to $38^{\circ}C$ respectively. The teak plantations in Cauvery canal bank which grow in continuous moisture condition (8-10 months) retain the leaf for longer period due to moisture resulting continuous supply of photosynthates leads to fast and outstanding growth. The girth at breast height (GBH) of 34-years-old tree in canal area was similar to that of 40 to 49-years-old trees in other locations, indicating that teak plantations with regular watering and silvicultural practices may be harvested at the age of 30 years. The leaf fall, flowering and fruiting showed significant variations in different teak plantations due to environmental factors and altitudes. It was found that increase of rainfall enhances number of flowers in the inflorescence in teak. Tholpatty (block-IV) showed more flowering in a inflorescence (3,734-3,744) compared to other plantations (1,678-3,307). Flowering in Nilambur and Wayanad coincided with heavy rainfall resulting low fruitset (1.1-2.3%) probably heavy rainfall ensuing restriction of pollinators for effective pollination. On the other hand, flowering in Cauvery canal bank (Block-I) was not coincided with high rainfall exhibited high fruitset (2-3%). About 66 to 76% of the fruits in different plantations were empty, and it is one of the main reasons for poor germination in teak. The seeds of Topslip and Parambikulam (Block-II) showed higher seed weight, maximum seed filling and good germination indicating that the environmental factors and altitude play significant role in fruit setting and seed filling in teak. In addition, the teak plantations in Topslip and Parambikulam showed good growth suggesting that plantations in the altitude range of approximately 550-700 m may be suitable for converting into seed production areas for production of quality seeds.

• Restorative Dentistry and Endodontics
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• 제35권5호
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• pp.335-343
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• 2010

연구목적: 본 연구의 목적은 수종의 sealer를 이용하여 각기 다른 양의 잔여수분이 존재하는 근관을 충전 시, 근관충전의 sealing ability를 glucose leakage model로 평가하는 것이다. 연구 재료 및 방법: 발치된 90개의 단근치를 치관부를 잘라내고 #45 / 0.06 taper까지 확대한 후, 12개의 실험군 (n = 7)과 2개의 대조군 (n = 3)으로 나누었다. 실험군을 3가지 습윤 상태에서 (a, DRY; b, PAPER POINT DRY; c, WET) 4종류의 sealer로 (Group 1-3: Sealapex; Group 4-6: AH plus; Group 7-9: Tubuli-seal; Group 10-12: EndoRez), warm vertical compaction method를 이용해 충전하였다. $37^{\circ}C$, 습도 100%에서 7일 동안 보관하고 glucose leakage model을 이용하여 치관부로부터 치근부 방향의 미세누출을 정량화하였다. 1, 3, 7, 14, 21, 30일 째 누출된 glucose의 농도를 spectrophotometer로 측정하였다. 결과: 관찰기간 동안 AH plus/DRY군 (Group 4)이 12개 그룹 중 가장 적은 양의 leakage를 보였다 (20.78 mmol/L). 반면에 Tubuli-seal/WET군 (Group 9)이 12개 그룹 중 가장 높은 양의 leakage를 보였다 (178.75 mmol/L). 결론: 본 연구의 결과는 충전 시 근관 내의 습윤 상태와 sealer 종류가 microleakage에 유의한 영향을 미친다는 것을 입증하였다. 그러므로 sealer 종류에 따라 각기 다른 근관 건조 방법을 사용하는 것이 근관치료에서 더 좋은 결과를 얻을 수 있는 방법일 것이다.

• 한국농공학회지
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• 제21권2호
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• pp.28-36
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• 1979

One of most important problems in the Monsoon Asia today is the production of rice paddy to meet the needs of the ever increasing population. Diversemeans are being employed to meet this demand, both by increasing productivity of existing farm land and by bringing further areas into cultivation. The primary step in either field is to ensure that there is sufficient moisture in the soil to suit the paddy, and at the same this means that excess moisture has to be drained off the land, while in others irrigat ion has to be employed to bring sufficient water to an area. In view of the fact that the project comprises a huge amount of earthwork, it can be carried out by extensive use of construction machinery in order to shorten the period. As farm ditch has a comparatively small section with shallow cutting depth, inaddition, there is lack of access road in the field, the excavation equipment with bulldozer or tracter-shovel (backhoe) type are not applicable because there are mostly adapted for the excavation of deep and wide section. Mini-backhoe with its bucket width not larger than 0. 3m, and width of blade not larger than 1. 00m seems to be more adaptable. About 80% of excavation of ditch section will be done by the machinery while the other 20% of excavation together with the finishing of the section are supposed to be done by man-power. The embankment of ditch section can be compacted by the crawler of backhoe when it is moving along the ditch for excavation. However, Lowland paddy field in the Monsoon Asia are made particulary in rain season, therefore, heavy machinery is not easy excavation for ditch. It is very important to know exact ground support power of the working site and select machines with corresponding ground pressure. Ground support power is variable subject to quality and water content of soil and therefore selection of machines should be made duly considering ground condition of the site at the time of construction works. Farm ditches dug and compacted by mannual labar are of poor quality and subject to destruction after one or two years of operation. On the other hand, excavation and compaction by bulldozer is not practical for ditches. Backboe is suitable for slope land, but this is required cycle time of bucket excavation and dumped out. If a small-scale farm ditch trencher adaptable to lowland paddy field is invented, such a machine could greatly accelerate the massive construction work envisaged in many countries and thus significantly speed up the most difficult part of irrigation development and management in Monsoon Asia.

• 한국잡초학회지
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• 제12권3호
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• pp.200-222
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• 1992

The results of recent researches for improvement of seedling stand in direct seeded rice on the dry paddy in Korea were summarized as the following ; a variety to be cultivated should be chosen the characteristics of high percentage germination under low temperature, shorter period of shoot emergence, and better growth of the mesocotyl and shoots. Meanwhile, there was 40% increase in seedling stand at the treatment of removal of the seed awn under using the drill seeder. After seeding the rice seed covered with soil of 3cm depth was better seedling emergence and also there was the hightest seedling emergence at the 70% of moisture content of the soil. In addition, the application of the Release containing GA 10% enabled to increase the seedling stand and furthermore it was effective under deep seeding depth. The optimum seeding date should be seeded around May 10 when mean air temperature is above 12-13$^{\circ}C$ so that may establish more less 70% in seedling stand. Based on an appropriate seedling stand of 150/$m^2$, the optimum seeding rate was 5kg/10a. It was the best in seeding method using drill seeder and the most desirable recommended seeding method was the drill seeder in terms of seedling stand. In order to improve seedling stand water management was more effective in canal irrigation and in drainage at 6hr after irrigation following by the seeding process. On the other hand, for the increase of seedling stand under flooded condition a variety might have characters being better germination at low concentration of dissolved oxygen and vertically deeper growing of the crown root. Also, seedling stand was able to increase with the seed coating of $CaO_2$in the flooded soil. It was possible to be seeded on the early part of May being mean air temperature of avove 10$^{\circ}C$ and the optimum seeding rate was 5kg/10a. For an effective water management water would be flooded up to 3cm depth for 2-3 weeks after seeding. The rice plant grown under the direct seeded cultivation might be not so much strong in lodging resistance compared to that grown under the transplanting and moreover direct seeded rice cultivation under flooded condition would be more weak growth of the rice plant than that on dry paddy. Meanwhile, the lodging would be affected by the seeding rate, the soil depth after seeding. and seeding method even in the same variety. In particular, roots in the lodging pattern of direct seeded rice cultivation under flooded condition were largely distributed on the soil surface so that resulted easily in the lodging. In general, the lodging resistance would be greater as seeding rate and amount of N fertilizer application are lower and soil depth after seeding is higher. Among the introduction of different seeding method the high ridged drill seeding method on dry paddy soil resulted in the lowest in the lodging index and also it was lower in the drill seeding method than in the scattering seeding method under flooded condition. In case of more than 150 seedlings per $m^2$ there was a severe lodging due to high lodging index at the 3rd and 4th internodes. The effective lodging prevention was able to at the treatment of the Inabenfide at 45 days before heading and the Uniconazol at 15 days before heading which caused the shortage by 10-15cm in culm length. Also, fertilizer management using split application of nitrogen would be contributed the reduction of lodging at the rate of 20-30-20-20-10%(basal-5th leaf stage-7th leaf stage-panicle initiation stage-heading stage) on the dry paddy soil.