• Title/Summary/Keyword: effect of desiccation

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Effects of desiccation on the consolidation behavior of dredged and reclamated soil during period of reclamation (매립기간 중 건조효과가 준설매립토의 압밀거동에 미치는 영향)

  • Kim, Jin-Tae;Ahn, Jung-Seon;Yoo, Nam-Jae
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.10a
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    • pp.515-520
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    • 2006
  • Yano method had been used in predicting the settlement of self-weight consolidation of dredged soil in the construction of reclamating the dredged soil. Its estimation was found to show some different results from field measurements. The numerical analysis with PSDDF was peformed find such differences, considering the effect of desiccation on the consolidation during the remaining time after reclamation. For the parametric study, numerical analyses with/without consideration of desiccation were carried out with changing the conditions of desiccation such as the number of placing the fill and the time period between each placement. As results of analysis, estimations about consolidation settlement and distribution of water contents with consideration of desiccation was in good agreements with field measurements. It was also found that the number of placing the fill and the time period between each placement did not affect the behavior of self-weight consolidation as much as the effect of desiccation.

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Behaviour of Consolidation in Dredged and Reclaimed Soil Considering the Effect of the Desiccation (건조효과를 고려한 준설매립토의 압밀거동)

  • Yoo, Nam-Jae;Park, Byung-Soo;Lee, Myung-woog;Lee, Joo-Won
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.93-100
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    • 2000
  • This research is to investigate the self-weight consolidation settlement and desiccation shrinkage settlement of soft marine dredging clay by performing numerical and experimental works. Large column test were carried out investigate the consolidation settlement considering effect of the self-weight and desiccation shrinkage, and centrifuge model test was also carried out investigate self-weight consolidation settlement. Results of centrifuge model and large column experiments about changes of settlement with time were analyzed by using the numerical technique of explicit finite difference method considering effect of the self-weight and desiccation based on the finite strain consolidation theory. Centrifuge model test results were in relatively good agreements with analyzed results in terms of self-weight consolidation settlement with time. Large column test results showed quite different values from the numerically estimated one, carried by experimental conditions.

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Improvement of Corrosion Resistance of Aluminum Alloy with Wettability Controlled Porous Oxide films

  • Sakairi, M.;Goyal, V.
    • Corrosion Science and Technology
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    • v.15 no.4
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    • pp.166-170
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    • 2016
  • The combined process of porous type anodizing and desiccation treatment was applied to improve wettability of A1050 aluminum alloy. The water contact angles of anodized samples were increaseds considerably with desiccation treatment. However, there was no considerable effect of polishing and anodizing time on water contact angle. The corrosion behavior with the treatments was investigated electrochemically. The corrosion resistance of the samples in 3.5 mass% NaCl solutions increased with higher contact angle. Anodized and desiccated samples showed better corrosion resistance than un-desiccated samples around rest potential region.

A Study on Characteristics of Strength Increase and Bearing Capacity in Dredged and Reclaimed Soil due to Desiccation Shrinkage (준설토의 건조수축에 의한 강도증가 특성과 지지력에 관한 연구)

  • Yoo, Nam-Jae;Lee, Jong-Ho;Lee, Myung-Woog;Kim, Hyun-Joo
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.101-111
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    • 2000
  • This research is results of experimental and numerical works on characteristic of strength increase and bearing capacity in dredged and reclaimed soil due to desiccation shrinkage. For a soil sampled from southern coastal area in Korea, basic soil property tests and standard consolidation test with falling head permeability tests were carried out to obtain consolidational characteristics of soil. Double cone penetration test, laboratory vane test and unconfined compression test were also performed to investigate the change of shear strength with degree of desiccation. Model tests were performed in 1G environment and 30G level artificially accelerated condition by using the centrifuge model test facilities to investigate the bearing capacity of desiccated ground. Test results were analyzed by using the theoretical and load-settlement characteristics method proposed by Meyehof & Hanna(1978). On the other hands, the numerical technique, using the finite strain consolidation theory considering the effect of desiccation was used to estimate the appropriate time of using heavy construction equipments in field with respect to strength increase due to desiccation.

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Sorbitol-Facilitated Preconditioning Improves Desiccation Resistance of Douglas-fir and Western Hemlock Seedlings

  • Guak Sung-Hee
    • Journal of Bio-Environment Control
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    • v.15 no.1
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    • pp.100-106
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    • 2006
  • A hypertonic solution of sorbitol was used to precondition Douglas-fir and Western hemlock plug seedlings to improve desiccation resistance. Seedlings were preconditioned by soaking their root balls in water, -0.75 or -1.50 MPa sorbitol solution for 22 hr, and then exposed to desiccation conditions for 8 days. During the desiccation period, a transpirational water loss was significantly reduced by the sorbitol preconditioning, with its effect positively depending on concentration. This preconditioning-induced reduction in water loss was mainly caused by the decline in needle stomatal conductance. Sorbitol-induced stomatal control was more closely associated with reduction in plant water potential, rather than increase in abscisic acid concentrations. After rehydration of stressed-plants, most of the preconditioned seedlings with sorbitol were survived, while only 35% of Douglas-fir and 28% of Western hemlock seedlings treated with water were alive. The post-growth was significantly greater in the preconditioned seedlings than only water-treated seedlings. These results suggested that the earlier stomatal control with sorbitol-facilitated preconditioning could play a role in improving desiccation resistance of evergreen woody plants at transplanting in the field where water supply is limited or dry conditions are prevailing.

Effects of Light, Desiccation and Salinity for the Spore Discharge of Gracilaria verrucosa (Rhodophyta) in Korea

  • Kim Young Sik;Choi Han Gil;Nam Ki Wan
    • Fisheries and Aquatic Sciences
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    • v.4 no.4
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    • pp.257-260
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    • 2001
  • The effects of light, desiccation and salinity on the discharge of spores in Korean agarophyte, Gracilaria verrucosa were studied. Among the examined factors, light after darkness was the most effective for spore discharge. The maximum release of tetraspores was induced at 24 h after the treatment. Desiccation also seems to be conductive to the release of tetraspores. However, its effect, as in treatment of distilled water for salinity, was hardly found in induction of carpospore discharge. This may suggest that spore discharge in this alga is primarily related with photoperiodic rhythm. Also it appears that the amount of light energy received by fertile thalli also significantly affects to the spore release, considering relationship between the amount of the discharged spores and the elapsed time after treatment.

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Effect of film liner packaging with chlorine dioxide on the storage quality of containergrown or bare-root seedlings at cold or frozen temperatures in sawtooth oak and Japanese larch

  • Yu-Rim, Kim;Min-Seok, Cho;Byung-Bae, Park;Jong-Pil, Chun
    • Korean Journal of Agricultural Science
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    • v.48 no.4
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    • pp.753-760
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    • 2021
  • This study was carried out to discover suitable packaging methods during the cold or frozen storage of sawtooth oak and Japanese larch seedlings, which are major afforestation tree species in Korea. The weight loss rate of sawtooth oak was lower under frozen storage at -2℃ (maximum, 33.7%) than under cold storage at 2℃ (maximum, 61.0%). A film liner treatment inside the packaging box effectively suppressed the increase in the weight loss rate. For the sawtooth oak containerized seedlings, when stored at -2℃, the rate of weight loss was 17.9 to 25.4% in the untreated group and less than 1% in the film liner treatment group. Similar results were observed with Japanese larch. After two months of freezing at -2℃, both species maintained a low index of 1.0 - 1.1 with regard to the degree of shoot desiccation of containerized seedlings, and there was no significant difference between the treatments. On the other hand, the chlorine dioxide treatment could more effectively reduce the occurrence of mold and shoot desiccation than a PE single treatment in bare-root seedlings. According to these results, it was concluded that frozen storage is generally suitable as a means of long-term storage compared to cold storage of sawtooth oak and Japanese larch. A chlorine dioxide treatment at 20 ppm was effective for maintaining seedling quality levels during storage, demonstrating the good effect of suppressing the occurrence of shoot desiccation and the occurrence of mold.

Effect of Seed Coat Softening, Washing and Drying on Seed Germination of Gourd (종피의 연화처리, 세척 및 건조가 박 종자의 발아에 미치는 영향)

  • 강진호;강신윤;전병삼;이상우
    • Journal of Life Science
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    • v.12 no.6
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    • pp.694-699
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    • 2002
  • The present experiment was carried out to determine the effect of seed-coat softening by various chemicals, washing, chilling, and light treatment alone and in combination during desiccation of seeds on germination of gourd (Lagenaria siceraria Standl.) seeds. Potassium hydroxide, sodium hydroxide, acetone, acetonitrile, and acetamide were used as chemicals for the softening. Washing, prechilling, drying and light treatment of the softened seeds were done for a hour with tap water, for one or three weeks at 3$^{\circ}C$, 12 hr at 35$^{\circ}C$, and 14 hr a day at 3$0^{\circ}C$ with red light illumination or darkness, respectively. FR-yongjadaemok and FR-kunghap were used as test cultivars. Seed-coat softening with 10% acetone and acetonitrile for 1 hour enhanced and accelerated seed germination compared to the other chemicals and water imbibition. KOH treated for the softening was necessary to increase the germination rate of seeds for following chilling, but acetone did not influence their germinability regardless of chilling. Washing the softened seeds in tap water increased the germination rate in comparison with no-washing. During desiccation of the seeds sequentially treated with the softening, washing and chilling, red light treatment showed higher germination rate than dark one, suggesting that red light treatment are necessary during desiccation.

Evaluating Early Age Shrinkage Behavior of Ultra High Performance Cementitious Composites (UHPCC) with CSA Expansive Admixture and Shrinkage Reducing Agent (CSA계 팽창재 및 수축 저감제의 혼입에 따른 UHPCC의 초기 수축 거동 평가)

  • Yoo, Doo-Yeol;Park, Jung-Jun;Kim, Sung-Wook;Yoon, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.23 no.4
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    • pp.441-448
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    • 2011
  • In this study, experimental tests of chemical and autogenous shrinkage were performed to evaluate the early age shrinkage behaviors of ultra high performance cementitious composites (UHPCC) with various replacement ratios of silica fume (SF), shrinkage reducing agent (SRA), expansive admixture (EA), and superplasticizer (SP). Starting time of self-desiccation, was analyzed by comparing the setting times and the deviated point of chemical and autogenous shrinkage strains. The test results indicated that both SF and SRA augment the early age chemical shrinkage, whereas SP delays the hydration reaction between cement particles and water, and reduces chemical shrinkage. About 49% of autogenous shrinkage was depleted by synergetic effect of SRA and EA. The hardening of UHPCC was catalyzed by containing EA. Self-desiccation of UHPCC occurred prior to the initial setting due to the high volume fraction of fibers and low water-binder ratio (W/B).