• Title/Summary/Keyword: WATER STRESS

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An Outlook of Agricultural Drought in Jeonju Area under the RCP8.5 Projected Climate Condition (기후변화 시나리오에 근거한 전주지역의 농업가뭄 전망)

  • Kim, Dae-jun;Yun, Jin I.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.17 no.4
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    • pp.275-280
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    • 2015
  • In order to figure out the future drought characteristics of the Jeonju plains, the major crop production area in Korea, daily agricultural drought indexes based on soil water balance were calculated for the relevant 12.5 km by 12.5 km grid cell using the weather data generated by the RCP8.5 climate scenario during 1951-2100. The calculations were grouped into five climatological normal years, the past (1951-1980), the present (1981-2010), and the three futures (2011-2040, 2041-2070, and 2071-2100). Results showed that the soil moisture conditions in early spring, worst for both the past and present normal years, will ameliorate gradually in the future and the crop water stress in spring season was projected to become negligible by the end of this century. Furthermore, the drought frequency in early spring was projected to diminish, resulting in rare occurrence of spring drought by that time. However, the result also showed that the soil moisture conditions during the summer season (when most crops grow in Jeonju plain) will deteriorate and the drought incidence will be more frequent than in the past or present period.

Effect of spinning parameters of polyethersulfone based hollow fiber membranes on morphological and mechanical properties

  • Tewfik, Shadia R.;Sorour, Mohamed H.;Shaalan, Hayam F.;Hani, Heba A.
    • Membrane and Water Treatment
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    • v.9 no.1
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    • pp.43-51
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    • 2018
  • Hollow fiber (HF) membranes are gaining wide interest over flat membranes due to their compaction and high area to surface volume ratio. This work addresses the fabrication of HF from polysulfone (PS) and polyethersulfone (PES) using N-methylpyrrolidone (NMP) as solvent in addition to other additives to achieve desired characteristics. The semi-pilot spinning system includes jacketed vessel, four spinneret block, coagulation and washing baths in addition to dryer and winder. Different parameters affecting dry-wet spinning phase inversion process were investigated. Dope compositions of PES, NMP and polyvinyl pyrrolidone (PVP) of varying molecular weights as additive were addressed. Some critical parameters of importance were also investigated. Those include dope flow rate, air gap, coagulation & washing baths and drying temperatures. The measured dope viscosity was in the range from 1.7 to 36.5 Pa.s. Air gap distance was adjusted from 20 to 45 cm and coagulation bath temperature from 20 to $46^{\circ}C$. The HF membranes were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical properties. Results indicated prevalence of finger like structure and average surface roughness from about 29 to 78.3 nm. Profile of stress strain characteristics revealed suitability of the fibers for downstream interventions for fabrication of thin film composite membrane. Different empirical correlations were formulated which enable deeper understanding of the interaction of the above mentioned variables. Data of pure water permeability (PWP) confirmed that the fabricated samples fall within the microfiltration (MF)-ultrafiltration (UF) range of membrane separation.

A numerical study on the effect of train-induced vibration in shield tunnel (쉴드터널 내부에 작용하는 열차진동 영향에 관한 수치해석적 연구)

  • Kwak, C.W.;Park, I.J.;Park, J.B.
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.2
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    • pp.261-267
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    • 2014
  • Various types of external loads can be applied to the tunnel structure. In a shield tunnel, the vibration from the train may affect the behavior of the adjacent ground. In this study, the railway-induced vibration was estimated and applied to the shield tunnel through 3D numerical simulation. The effective stress analysis based on the finite difference method and Finn model was performed to investigate the potential of liquefaction below the tunnel. Furthermore, pore water pressure and displacement were monitored on a time domain; consequently, the liquefaction potential and dynamic response of the shield tunnel were analyzed. Consequently, it is confirmed that the generation of excess pore water pressure by train-induced vibrating load, however, the amount does not meaningfully affect the potential of liquefaction.

The Antifibrotic and Antioxidant Activities of Hot Water Extract of Adventitious Root Culture of Panax ginseng (ARCP)

  • Lim, Hee-Kyoung;Kim, Youn-Woo;Lee, Dae-Ho;Cho, Somi-Kim;Cho, Moon-Jae
    • Journal of Applied Biological Chemistry
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    • v.50 no.2
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    • pp.78-84
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    • 2007
  • The anti-fibrotic effects of hot water extract of adventitious root culture of Panax ginseng (ARCP) and the possible mechanisms were investigated on $CCl_4-induced$ hepatotoxicity model mice. Fibrosis was induced by a mild treatment of $CCl_4$. Then silymarin as a positive control drug and ARCP or carrier alone as a negative control were treated. Serum GPT, GOT and ALP activity levels were lowered by 25, 21 and 11% for silymarin treated group and by 48, 39 and 14% for ARCP treated group compared to carrier treated alone. Hepatic collagen for ARCP treatment group was reduced by 18% and MDA contents decreased a little more. Pro-fibrotic gene ($TGF-{\beta}1$, TIMP-1 and ${\alpha}-SMA$) expression increased following the $CCl_4$ treatment, but both the silymarin and the ARCP treatments decreased the expressions of these genes by 20% to 50%. The antioxidant effect of ARCP was studied by DPPH free radical scavenging activity. In addition, a generation of reactive oxygen species (ROS) was also reduced in $H_2O_2-treated$ HepG2 cells upon the ARCP treatment. In summary, ARCP has antioxidant property, and can have some protection against oxidative stress; more importantly, ARCP can efficiently protect mice against $CCl_4-induced$ fibrosis.

Fabrication of Titanium alloy by Electromagnetic Continuous Casting (EMCC) Method for Medical Applications (전자기 연속 주조법을 이용한 의료용 타이타늄 합금 제작에 관한 연구)

  • Choi, Su-Ji;Lee, Hyun-Jae;Baek, Su-Hyun;Hyun, Soong-Keun;Jung, Hyun-Do;Moon, Byung-Moon
    • Journal of Korea Foundry Society
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    • v.38 no.1
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    • pp.9-15
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    • 2018
  • Electromagnetic continuous casting (EMCC) was used to fabricate Ti-6Al-4V alloys with properties suitable for medical applications. Ti-6Al-4V alloy ingots fabricated by EMCC were subjected to heat treatment, such as residual stress removing (RRS), furnace cooling after solution treatment (ST-FC) and water-cooling after solution treatment (ST-WC), in order to obtain characteristics suitable for the standard. After component analysis, the microstructure and mechanical properties (tensile strength and elongation) were evaluated by ICP, gas analysis, OM, SEM, a Rockwell hardness tester and universal testing machine. The Ti-6Al-4V alloy ingot fabricated by EMCC was fabricated without segregation, and the lamellar structure was observed in the RRS and ST-FC specimens. The ST-WC specimen showed only martensite structure. As a result of evaluating the mechanical properties based on the microstructure results, we found that the water-cooled heat treatment condition after the solution treatment was most suitable for the Ti-6Al-4V ELI standard.

Research Trend of Aquatic Ecotoxicity of Gold Nanoparticles and Gold Ions (금나노입자 및 금이온의 수서생태독성 연구동향)

  • Nam, Sun-Hwa;An, Youn-Joo
    • Journal of Korean Society on Water Environment
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    • v.28 no.2
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    • pp.313-319
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    • 2012
  • Various nanomaterials may flow into the aquatic ecosystem via production, use, and treatment processes. Especially, gold nanoparticles (AuNPs) were categorized as manufactured nanomaterials presented by the Organization for Economic Cooperation and Development Working Party on Manufactured Nanomaterials (OECD WPMN) in 2010. AuNPs have been used in medical area, however, they were reported to induce cytotoxicity and oxidative DNA damage, as well as down-regulation of the DNA repair gene in mice and human cell lines. In this study, the aquatic toxicity data of AuNPs and gold ions were collected, with the specific test methods analyzed with respect to the form and size of AuNPs, test species, exposure duration, and endpoints. Currently, aquatic toxicity data of AuNPs and gold ions have been presented in 14 studies including 4 fish, 6 crustacean, 2 green algae, and 2 macrophytes studies, as well as a further 8 studies including 4 fish, 4 crustacean, 1 platyhelminthes, and 1 green algae, respectively. The AuNPs were 0.8-100 nm in size, as gold nanoparticles, gold nanorod, glycodendrimer-coated gold nanoparticles, and amine-coated gold nanoparticles. The tested endpoints were the individual toxicities, such as mortality, malformation, reproduction inhibition, growth inhibition and genetic toxicity such as oxidative stress, gene expression, and reactive oxygen species formation. The accumulation of AuNPs was also confirmed in the various receptor organs. These results are expected to be useful in understanding the aquatic toxicity of AuNPs and gold ions, as well as being applicable to future toxicity studies on AuNPs.

The analysis about the course of studying renal stones -On the basis of incurable and relapse renal stones' differentiation of symptoms and signs- (요로결석(尿路結石) 연구동향(硏究動向)에 대한 분석(分析) - 난치(難治)와 재발(再發)의 판증(辦證)을 중심으로 -)

  • Lee, Jung-Won;Kim, Chueng-Jung;Cho, Chung-Sik
    • Journal of Haehwa Medicine
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    • v.14 no.2
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    • pp.143-151
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    • 2005
  • Gobjectives and Methods to investigate into the course of incurable and relapse renal stones' differentiation of symptoms and signs and to effectively improve treatment of incurable and relapse renal stones through Oriental Medicine. To search for the papers about treatment of incurable and relapse renal stones from 1994 till 2004, and re-search papers about treatment for indicated differentiation of disease. Result and conclusions : 1. It is the kidney vacuity additionally the deficiency of qi(氣) in middle-burner that the incurable and relapse renal stones' differentiation of disease. 2. The cause is taking an overdose of attacking renal stones to eliminate dampness and heat medicine, aging, chrome disease. a sex act excess, insufficiency of congenital qi(氣), insufficient exercise, wrong treatment and stress. 3. Herb medicines are constituted supplementing kidney drugs for inhibition of renal stone's creation, drugs to diuresis and dissolve calculi, and drugs 10 exclude stasis blood(瘀血) on account of renal stones. 4. Anti-renal stone measures me sufficiently drinking water, not eating greasy food. taking medicine for supplementing kidney, diuresis and dissolve calculi by periods, and drinking substitute water to boll down medical herb as Lysimachiae Herba (金錢草) Polygoni Avicularis Herba(篇蓄).

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Mechanical Constitutive Model for Frozen Soil (동토지반에 대한 역학적 구성모델)

  • Shin, Ho-Sung;Kim, Ji-Min;Lee, Jang-Guen;Lee, Seung-Rae
    • Journal of the Korean Geotechnical Society
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    • v.28 no.5
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    • pp.85-94
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    • 2012
  • Recently, growing interests in frozen ground have stimulated us to advance fundamental theories and systematic researches on soil behavior under freezing conditions. Unlike the well-established soil mechanics theory, temperature variation and phase change of pore-water cause water migration to cold side, ground heaving, sharp increase in earth pressure, etc., which bring about serious problems in frozen geotechnical structures. Elasto-plastic mechanical constitutive model for frozen/unfrozen soil subjected to fully coupled THM phenomena is formulated based on a new stress variable that is continuous in frozen-unfrozen transitional regions. Numerical simulations are conducted to discuss numerical reliability and applicability of the developed constitutive model: one-dimensional heaving pressure, tri-axial compression test, and one-side freezing tests. The numerical results show that developed model can efficiently describe complex THM phenomena of frozen soil, and they can be utilized to analyze and design the geotechnical structures under freezing conditions, and predict their long-term behavior.

The Effect of Displacement Rate on Shear Characteristics of Geotextile-involved Ceosynthetic Interfaces (지오텍스타일이 포함된 토목섬유 경계면의 전단특성에 대한 변위속도 효과)

  • 김진만
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.173-180
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    • 2003
  • In spite of its potential importance in the assessment of geosynthetic-related dynamic problems, no serious attempt has yet been made to investigate a probable dependence of dynamic friction resistance of the geosynthetic interface on shear displacement rate. Hence, an experimental study of geosynthetics was carried out on a shaking table, and the relationship between dynamic friction resistance and shear displacement rate of geosynthetic interfaces was investigated. A cyclic, displacement rate-controlled experimental setup was used. The subsequent multiple rate tests showed that interfaces that involve geotextiles have such unique shearing characteristics that shear strengths tend to increase with displacement rate. In contrast, once submerged with water, the shear strength appears to be no longer dependent on the displacement rate, partly due to lubrication effect of water trapped inside the interface. The results of the experimental study can be used in the seismic safety assessment of a landfill cover and slope where the geosynthetic materials are exposed to a relatively low normal stress.

Evaluation on the leakage of ground-water through fractured rock under a spillway (여수로 구조물 하부 암반 내 발달한 절리들을 통한 지하수 누수량 분석)

  • Kim, Hyoung-Soo;Lee, Ju-Hyun;Jeong, Ui-Jin;Lee, Joong-Woo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.69-74
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    • 2006
  • Recently, spillways are need to control stable water level for supporting main dams because of floods by unusual change of weather such as Typhoon Rusa. This study has been focused on the amount of leakage through the rock mass distributed fractures and joints under the opened emergency spillway. It is very important to evaluate the amount of leakage as these affect stability of spillway by interaction between effective stress and pore pressure. The commercial program MAFIC has been used for analyzing groundwater flow in fractured rock mass. The results showed that the values of range, average and deviation of leakage were $2.85\sim\;3.79\times10^{-1}$, $3.32\times10^{-1}$ and $1.70\times10^{-2}\;m^3/day/m^2$ respectively. Secondary, we have estimated the effect of grouting after the transmissivity$(T_f)$ of joint 1 as main pathway of leakage known from above results was changed from $1.78\times10^{-7}$ to $1.59\times10^{-9}\;m^2/s$. The results showed that the values of range, average and deviation of leakage were $7.80\times10^{-4}\sim1.53\times10^{-3}$, $1.18\times10^{-3}$ and $1.32\times10^{-4}\;m^3/day/m^2$ respectively. As the result, the amount of leakage after grouting has been decreased by a ratio of 1 to 277.

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