• 제목/요약/키워드: Soil drying

검색결과 229건 처리시간 0.029초

TDR 측정시스템이 도입된 압력판 추출 시험기를 이용한 흙-함수특성곡선 연구 (Soil Water Characteristic Curve Using Volumetric Pressure Plate Extractor Incorporated with TDR System)

  • 정영석;사희동;강성훈;오세붕;이종섭
    • 한국지반공학회논문집
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    • 제31권8호
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    • pp.17-28
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    • 2015
  • 흙-함수특성곡선에 대한 선행 연구결과들의 경우, 정량적으로 간극수 유출입량을 측정하여 모관흡수력에 따른 체적함수비를 산정하였다. 본 연구에서는, 압력판 추출시험기(VPPE)에 Time Domain Reflectimoetry(TDR) 측정 시스템을 도입하여 불포화토의 건조과정 및 습윤과정 진행에 따른 유전상수를 측정하여 체적함수비를 산정하고자 하였다. 압력판 추출 시험기는 압력셀, 압력조절장치, 뷰렛 시스템, TDR 프로브로 구성된다. 압력셀에 초기 간극비가 다른 두 시료를 조성한 후, 압력조절장치를 이용하여 압력셀 내부에 0.1kPa - 50kPa 범위의 공기압을 가하여 모관흡수력을 조절하였다. 그리고 뷰렛시스템을 이용하여 모관흡수력 변화에 따른 시료의 체적함수비 변화를 측정하였다. 또한, 압력셀 내부에 설치된 TDR 프로브를 이용하여 프로브 양단에서 발생되는 전자기파의 반사 신호로부터 유전상수를 산정하였다. 주문진 표준사의 체적함수비 변화에 따른 유전상수 측정에 대한 보정으로 도출한 체적함수비와 유전상수관계를 이용하여 시료의 체적함수비를 산정하였다. 실험 결과, 시료의 초기 간극비와 상관없이 TDR 프로브에 의해 산정된 체적함수비는 뷰렛 시스템을 통해 정량적으로 산정된 체적함수비와 매우 유사한 것으로 나타났다. 또한, 건조과정 및 습윤과정 진행에 따라 동일한 모관흡수력에 대한 함수비의 차이가 존재하는 이력현상(Hysteresis)이 발생하였고, 건조과정 및 습윤과정의 반복에 따라 이력현상은 줄어들었다. 본 연구에서 적용된 전자기파의 시간영역반사법(TDR)을 통해 불포화토의 흙-함수특성곡선을 효과적으로 파악할 수 있을 것으로 판단된다.

골재 중 0.08 mm 이하 미립분의 종류가 콘크리트의 특성에 미치는 영향 (The Influence of Fine Particles under 0.08 mm Contained in Aggregate on the Characteristics of Concrete)

  • 송진우;최재진
    • 콘크리트학회논문집
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    • 제25권3호
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    • pp.347-354
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    • 2013
  • 최근 천연모래의 부족으로 부순 잔골재가 널리 사용되고 있다. 우리나라에서는 부순 잔골재 중의 0.08 mm 이하 미립분을 7% 이하로 제한하고 있으며 이는 ASTM의 규정과 유사한 것이나 그 외의 다른 나라의 규정과 비교할 때 상당히 엄격한 규정이다. 또한 부순 잔골재 중에는 파쇄 시에 발생하는 0.08 mm 이하 미립분을 20% 정도 포함하게 되며 물로 씻어내는 일도 용이하지 않을 뿐 아니라 자원이용의 극대화를 위해서도 잔입자량 한도의 상향 조정 가능 여부에 대한 검토가 필요하다. 그래서 이 연구에서는 0.08 mm 이하 미립분에 대한 특성 및 콘크리트 품질에 미치는 영향에 대한 실험을 실시하였으며, 비교를 위하여 실트 및 점성토 중의 미립분을 사용한 실험을 병행하였다. 미립분에 대해 실험한 결과 메틸렌블루 값은 부순 잔골재 중의 석분에 비하여 실트 및 점성토 중의 미립분에 대한 값이 보다 크게 나타났으며 또한 메틸렌블루 값은 packing density 및 액성한계, 소성한계와 높은 상관관계를 가지는 것으로 나타났다. 콘크리트 실험에서 동일한 슬럼프를 얻기 위한 고성능 감수제의 소요량은 미립분의 대체 사용량 증가에 따라 커지며, 메틸렌블루 값이 큰 미립분을 사용할 때 보다 크게 나타났다. 한편 부순 잔골재 중의 미립분을 20% 이내에서 대체 사용한 경우, 고성능감수제를 사용하여 반죽질기를 같게 한 콘크리트의 압축강도와 인장강도는 거의 변화가 없었으며 콘크리트의 건조수축량도 큰 차이를 보이지 않았다. 그러나 실트 및 점성토 중의 미립분을 대체 사용한 경우는 콘크리트의 강도가 현저히 저하하고 건조수축량도 크게 증가하는 것으로 나타났다.

국내 벤토나이트 완충재의 함수특성곡선 평가 (Evaluation of Soil-Water Characteristic Curve for Domestic Bentonite Buffer)

  • 윤석;전준서;이창수;조원진;이승래;김건영
    • 방사성폐기물학회지
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    • 제17권1호
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    • pp.29-36
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    • 2019
  • 원자력발전소를 운영하게 되면 사용후핵연료와 같은 고준위방사성폐기물이 필연적으로 발생한다. 이러한 고준위방사성폐기물을 처분하기 위해 심층처분방식이 가장 적합한 대안으로 알려져 있으며 고준위방사성폐기물은 공학적방벽과 천연방벽에 둘러 쌓여 지하 500~1,000 m 깊이의 심지층에 처분된다. 이 중 압축 벤토나이트 완충재는 공학적방벽의 가장 중요한 구성요소이다. 완충재는 처분용기와 자연 암반 사이에 위치해 있기에 주변 지하수 흐름으로부터 처분용기를 보호하고 처분 용기로부터 핵종이 유출되는 것을 저지하는 역할을 한다. 주변 지하수 흐름으로 인한 완충재의 불포화 함수특성 규명은 전체 공학적방벽의 성능을 평가하는데 있어 매우 중요하다고 할 수 있다. 따라서 본 연구에서는 실내 시험을 수행하여 국내 압축 벤토나이트 완충재의 건조밀도, 구속조건 여부, 그리고 건조 및 포화 이력에 따른 압축 벤토나이트 완충재의 함수특성곡선을 도출하여 분석하였다. 구속 조건하에서 건조밀도에 따른 함수특성곡선은 큰 차이를 보이지 않았다. 또한 비구속 조건이 구속 조건에 비해 보다 큰 수분흡입력을 나타냈으며, 아울러 포화 과정보다 건조 과정에서 보다 큰 수분흡인력이 측정되었다.

정적 및 동적 하중에서 모래의 액상화 발생 (Occurrence of Sand Liquefaction on Static and Cyclic Loading)

  • 양재혁
    • 한국지반공학회논문집
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    • 제17권6호
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    • pp.235-244
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    • 2001
  • 액상화는 비배수조건에서 흙 강도의 갑작스러운 감소에 기인한다. 이러한 흙 강도의 손실은 과잉간극수압의 발현과 관련된다. 본 연구에서는 최대 및 최소간극비에 영향을 미치는 세립분 함유량이 조사되었다. 또한 포화된 실트질 모래에 대한 정적 및 동적 삼축시험의 결과를 제시하였다. 이들 시험은 액상화강도와 정적 및 동적 거동 특성을 평가하기 위해 수행되었다. 시료는 새만금 유역에서 채취되었으며 공기건조되었다. 결과를 요약하면 다음과 같다. 1) 최대 및 최소간극비선은 유사한 경향으로 나타났다. 2) 최대 및 최소간극비는 20~30%의 세립분 함유량에서 얻어졌다. 3) 구속압력과 과압밀비가 증가할수록 액상화에 대한 저항은 증가하였다. 4) 불안정마찰각은 초기상대밀도의 증가와 함께 커졌다. 5) 유효응력비가 증가함에 따라 액상화에 대한 저항은 감소하였다.

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사할린도(島)의 PEAT 현황조사 (Survey of Peat Deposits in Skhalin Island)

  • 이윤환
    • 한국토양비료학회지
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    • 제27권4호
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    • pp.315-320
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    • 1994
  • This survey report introduced briefly peat deposits in SAKHALIN island of eastern SIBERIA continent. Peat industry was promoted as leading resources for development in this island by national control economic plan of central government before CIS. But development of deposit was left suspension of operation due to investment now. In southern area, about 10km from Yuzunosakhalinsk, two deposits of peat field were explored. One of them (Troisk) was suspended at begining stage of peat harvest from 300ha field and the other(Missilop) was producing the compact peat through drying and pulverizing from 350ha peat field which showed long run harvest activities. There are plenty of peat deposits near the Polonai Reika (river) in the central area of this island, At Zbaikaritz, 40km nothern area from Polonaisk, 135ha of peat field was developed. This field was left without working but established field preparation and could be able to be harvested any time if machines and utlities were settled. At southern suburb 10km from Polonaisk, about 40ha field of virgin deposit has been established planning for development. The plan involved estimated amount of peat, deposit depth, water level, drainage and leading road. The most of peat deposits accumulated from sphagnum moss. Texture is coarse but it contains more than 95% of organic carbon near to 0.5% of total nitrogen and acidity showed pH4-5.

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불포화 점성토의 거동예측을 위한 구성식 개발 (Development of Constitutive Model for the Prediction of Behaviour of an Unsaturated Clayey Soil)

  • 송창섭;장병욱
    • 한국농공학회지
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    • 제38권3호
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    • pp.101-110
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    • 1996
  • The aim of the work described in this paper is to develope a constitutive model for the prediction of an unsaturated clayey soil and to confirm the application of the model. To this end a series of suction controlled isotropic and triaxial compression tests are conducted on clayey soils. Matric suction is controlled by the axis translation technique using high air entry ceramic disk. Total volume change, air and water volume changes are measured by the device made for the experiment. The specimens are compacted by dynamic compaction using a half of Proctor compaction energy with the water contents of 5% drier than the optimum moisture contents. From test results, volume changes and deviator stresses are analyzed at each state and their relationships are formulated. And the application of the model to clayey soils is confirmed by the comparison between test and predicted results. During drying-wetting and loading-unloading processes for isotropic states, the agreement between predicted and test results are satisfactory. And predicted deviator stresses are well agreed with the test results in shearing process, but volumetric strain is not well agreed with the test results in high suctions.

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Numerical Study of Unsaturated Infinite Slope Stability regarding Suction Stress under Rainfall-induced Infiltration Conditions

  • Song, Young-Suk;Hwang, Woong-Ki
    • 지질공학
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    • 제24권1호
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    • pp.1-8
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    • 2014
  • Numerical stability analysis of an unsaturated infinite slope under rainfall-induced infiltration conditions was performed using generalized effective stress to unify both saturated and unsaturated conditions The soil-water characteristic curve (SWCC) of sand with a relative density of 75% was initially measured for both drying and wetting processes. The hydraulic conductivity function (HCF) and suction stress characteristic curve (SSCC) were subsequently estimated. Under the rainfall-induced infiltration conditions, transient seepage analysis of an unsaturated infinite slope was performed using the finite element analysis program, SEEP/W. Based on these results, the stability of an unsaturated infinite slope under rainfall-induced infiltration conditions was examined in relation to suction stress. According to the results, the negative pore-water pressure and water content within the slope soil changed over time due to the infiltration. In addition, the variation of the negative pore-water pressure and water content led to a variation in suction stress and a subsequent change in the slope's factor of safety during the rainfall period.

Production Practices for North American Ginseng: Challenges and Opportunities

  • Proctor John T.A.
    • 고려인삼학회:학술대회논문집
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    • 고려인삼학회 2002년도 학술대회지
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    • pp.212-226
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    • 2002
  • North American ginseng production may have been maximized in the traditional growing areas in the last decade and further increases may be in woods grown root, for niche markets. The marketplace demands high quality roots. Most problems leading to low quality roots start with the grower and can be avoided. These include poor site selection, inadequate soil drainage, untimely and poorly applied pesticides, and neglect of good sanitary practices. Selection of low lying sites increased the plant damage from frost in Ontario in May 2002. Seeding is still the major method of propagation of ginseng in spite of some success in culturing different parts of the plant. Opportunities exist for shortening the stratification period of North American ginseng seed to allow spring planting. This may reduce disease incidence. Since only one-third of ginseng seed sown ultimately produces plants harvested after 3 years any approach that reduces disease incidence and improves seed germination, seedling emergence and crop stand must be pursued. Disease is the major problem in ginseng cutivation from seed stratification, soil preparation prior to planting, right through to drying of the roots. Replant disease remains as an unresolved problem and needs full characterization and new approaches for control. Much progress has been made in research and related extension activities in disease control although challenges will arise such as with Quintozene and its replacement with Quadris for control of diseases caused by Rhizoctonia. Decreased labor populations and increased associated costs for ginseng production are causing rapid mechanization in every aspect of the ginseng industry. Engineers, machinery dealers, and fabricators, and growers are being challenged to increase efficiency by mechanization.

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Physical and Chemical Management Practices for Improving Water Quality in Channel Catfish Ictalurus punctatus Aquaculture

  • Seo, Jin-Won
    • 한국양식학회지
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    • 제15권1호
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    • pp.49-60
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    • 2002
  • Research on practices for improving water quality in channel catfish Ictalurus punctatus ponds was conducted at the Auburn University Fisheries Research Station, Auburn, Alabama, in 1998 and 1999. The objective of this two-year study was to determine better management practices to enhance water quality and improve production efficiency. In the first year, oxidation of bottom soil by drying, tilling, and applying sodium nitrate was performed (dry-till and dry-till with sodium nitrate treatments). The second year, based on the results obtained during the first year, precipitation of phosphorus (P) from water by applying gypsum was compared to the dry-till treatment (dry-till and dry-till with gypsum treatments). Control ponds were not subjected to bottom drying, tilling, sodium nitrate, or gypsum treatment. Channel catfish fingerings were stocked at 15,000/ha. In the first year, water in ponds from dry-till and dry-till with sodium nitrate treatments had lower concentrations (P < 0.01) of soluble reactive P, nitrate ($NO_{3} ^{-}) and nitrite ($NO_{2} ^{-}) nitrogen (N), total ammonia ($NH_3$) nitrogen, total suspended solids and turbidity, and higher values of pH, Secchi disk visibility, total alkalinity, total hardness, and calcium ($Ca^{2+}) hardness than water in control ponds. Ponds of the dry-till treatment also had lower concentrations (P < 0.01) of total P and total N than control ponds. Total fish production and survival rate did not differ among the treatments (P > 0.05). The findings suggested that drying and tiling pond bosoms between crops could achieve water quality improvement. Applying sodium nitrate to dry, tilled pond bosoms did not provide water quality improvement. In the second year, the treatment with the best results from the first year, dry-till, was compared with a dry-till with gypsum treatment. Enough gypsum was applied to give a total hardness of about 200 mg/L, and gypsum was reapplied as needed to maintain the hardness. Compared to the control, dry-till and dry-till with gypsum treatments had lower concentrations (P < 0.01) of total and soluble reactive P, total N, and total $NH_3$-N, and higher concentrations (P < 0.01) of dissolved oxygen. Ponds of the duty-till with gypsum treatment also had lower concentrations (P < 0.01) of chlorophyll $\alpha$, chemical oxygen demand, and total alkalinity than the control. Total fish production and survival rate did not differ (P > 0.05) among the treatments. These findings suggest that drying and tilling pond bosoms between crops and treating low hardness waters with gypsum could achieve water Quality improvement.

Rice variety IPB3S and IPB prima production technology to support food self-sufficiency in Indonesia

  • Aswidinnoor, Hajrial;Guntoro, Dwi;Sugiyanta, Sugiyanta;Wiyono, Suryo;Widodo, Widodo;Wijaya, Hermanu;Nindita, Anggi;Furqoni, Hafith
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.362-362
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    • 2017
  • Dissemination of IPB3S rice variety combined with cultivation technology named IPB Prima was aimed to introduce IPB research product particularly for IPB rice variety with high-yield character that is IPB3S. The rice variety IPB3S and IPB Prima cultivation technology was expected to be one of solution to improve rice productivity and accelerate to food self-sufficiency in Indonesia. Research sctivity was consist of three main research unit i.e. (1) Dissemination of IPB3S rice variety and IPB Prima production technology; (2) The development of Information and management web-based system (IMS) for planning and monitoring IPB3S and IPB Prima application distribution; and (3) The development of High-capacity grain drying system in Fluidized-bed drying ang in-store drying system. The objective of main research i.e. to introduce IPB high-yield rice variety, to accelerate rice productivity to support self-sufficiency, to develop integrated system model through fluidized and in-store drying, and to develop web-based management-information system in result analyzing IPB3S and IPB Prima distribution and technology application. The dissemination activities was arranged in two location. The first location was in Banyuwangi, East Java with total area 10.87 ha, consist of 8.91 ha planting area for IPB3S and 1.96 ha planting area for Ciherang. The second location is in Tegal, Middle Java with total planting area in 5 ha. The experiment was arranged in different treatment of varieties and cultivation method. The experiment consist of (1) rice variety Ciherang with conventional cultivation technology (P0); (2) rice variety Ciherang with IPB Prima cultivation technology (P1); (3) rice variety IPB3S with conventional cultivation technology (P2); (4) rice variety IPB3S with IPB Prima cultivation technology (P3). Planting distance for twin rows system is $50cm{\times}25cm{\times}12.5cm$. Planting distance for single row system is $25cm{\times}25cm$. The research result elucidated that productivity result in two location has different grades in similar trend. Experiment in Tegal resulted P0 result is $6.18ton\;ha^{-1}$, P1 result is $6.30ton\;ha^{-1}$, P2 result is $6.82ton\;ha^{-1}$, P3 result is $7.31ton\;ha^{-1}$. Experiment in Banyuwangi resulted optimum production of IPB3S variety productivity number are $7.29ton\;ha^{-1}$, while Ciherang are $6.73ton\;ha^{-1}$.

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