• Title/Summary/Keyword: 치환비율

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An Analysis of Behavior and Strength of Cement using Improved Materials by Laboratory Model Test (실내 모형실험에 의한 지반보강 개량체 특성 분석)

  • Oh, Philjin;Park, Minchul;Lee, Song
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.7
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    • pp.19-29
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    • 2012
  • For foundation of Port structure, it is essential geotechnical understanding about feature of ground and the geologic formation which is different to terrestrial ground. What is most important is the understanding of soft ground clay, which is much softer than terrestrial ground. To build foundation of a port structure which is mainly gravity based on the special geographical circumstance that is on the sea, the improvement method of foundation should be applied according to soft clay ground features. Therefore, in this study, the behaviors of improved materials with strength were analyzed on the soft clay foundation where suppose to be located the foundation of port structure. The laboratory model test has been conducted in 2 cases with unconfined compression strength of improved materials, 25kPa and 125kPa. Cement, water, and in-situ soft clay were combined at a fixed rate and made a shape of 5cm diameter ${\times}$ 70cm height column. Improved materials were located with replacement ratio(11%, 35% and 61%) in 38cm diameter ${\times}$ 80cm height cylinder. Finally, the stress distribution ratio on the improved materials and clay, settlement was analyzed by applying a load of 10kPa, 30kPa, and 50kPa.

Fractionation and Availability of Cu and Zn in Paddy Soils Following a Long-Term Applications of Soil Amendments (토양개량제를 장기연용한 논토양에서 구리와 아연의 분획화 및 유효도)

  • Jung, Goo-Bok;Lee, Jong-Sik;Kim, Won-Il;Yeon, Beong-Yeal;Ryu, In-Soo
    • Korean Journal of Soil Science and Fertilizer
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    • v.31 no.2
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    • pp.107-113
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    • 1998
  • We investigated the effects of a long term application of soil amendments such as lime, silicate, compost, or combinations of these materials on the contents of Cu and Zn in paddy soil and brown rice. The results obtained from a sequential extraction of Cu and Zn in paddy soils and brown rice, using $H_2O$, $KNO_3$, $Na_2$-EDTA and $HNO_3$ and showed that the most of Cu and Zn were NaOH-extractable (organically bound form) and $HNO_3$-extractable (sulfide and residual form). Cu contents of NaOH and EDTA extractable increased with the long term application of compost while the contents of Zn extracted by $KNO_3$ was decreased even though $HNO_3$ extractable-Zn was prominent chemical form in paddy soils. The percentage and contents of Zn, extracted by $KNO_3$ for each combination treatment of soil amendments, was decreased but the contents of Cu was not affected. The content of NaOH extractable-Cu was proportionally increased with increase in organic matter content irrespective of the extractants used in this experiment. The contents of Zn and exchangeable K were also increased with increase in organic matter content. However, we could not find any relationship between the extractable forms of Cu and Zn, and CEC, OM. while increase in CEC, contents of cations, and organic matter decreased the content of Cu in brown rice.

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A Study of Shrinkage Characteristics of Low Shrinkage Normal Strength Concrete With Boundary Restraint Condition (4변 구속조건을 갖는 초저수축 일반강도 콘크리트의 수축특성 연구)

  • Jeong, Jun-Young;Min, Kyung-Hwan;Lee, Dong-Gyu;Choi, Hong-sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.6
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    • pp.693-699
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    • 2016
  • In this study, the replacement effects of cementitious materials (fly ash, blast furnace slag, and blended mixtures) were assessed for normal strength concrete with very low shrinkage properties under $350{\mu}{\varepsilon}$ strain using a powder type shrinkage reducing agent. In addition, through mock-up tests of actual size walls restrained with four sides, the shrinkage characteristics using the power type shrinkage reducing agent were measured and the crack reducing ability was assessed. The slump and air contents were measured as the properties of fresh concrete, and the length changes of the prismatic specimens, $100{\times}100{\times}400mm$ in size, were measured for the shrinkage characteristics. To reduce the shrinkage of concrete, the maximum replacing ratio of the fly ash is effective to 20 percent; however, the use of blast furnace slag and ternary mixtures did not reduce the shrinkage.

Study on Rheological Properties of Mortar for the Application of 3D Printing Method (3D 프린팅 공법 적용을 위한 모르타르 구성성분 변화에 따른 레올로지 특성 연구)

  • Lee, Hojae;Kim, Won-Woo;Moon, Jae-Heum
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.1
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    • pp.16-24
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    • 2018
  • In this study, an experiment was conducted to analyze mortar based rheology for 3D printing method application. The tendency of rheological properties due to the change of W/B, binder type, replacement ratio, and super plasticizer which have a great influence on the flow characteristics of concrete was experimentally analyzed. Experiments were carried out by dividing into paste and mortar. In the paste experiment, rheology was analyzed by setting W/B, binder type, replacement ratio, and super plasticizer dosage as main variables. In the mortar experiment, the rheological properties of W/B and sand ratio were analyzed. As a result, as the W/B was increased, the viscosity decreased and the FA ratio to replace FA increased and the viscosity increased. In order to increase the fluidity, substitution of only 5% of SF reduces the shear stress and the viscosity is reduced by about 83%. Mortar rheological evaluation shows that there is a critical section where a large change occurs in the W/B 30 to 40% section. Also, in the same W/B, it is analyzed that there is a critical section where the shear stress increases more than twice in the sand ratio of 50~60%.

Syntheses of Disubstituted Polysilanes (Ⅱ): Sonochemical Study (폴리실란의 합성 (Ⅱ): 초음파 화학적 연구)

  • 이규환;전태하
    • Journal of the Korean Chemical Society
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    • v.43 no.1
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    • pp.28-42
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    • 1999
  • Polysilanes with sterically bulky substituents, -[2-( $R^1R^2$-phenyl)propyl]Si[$R^3$]-, such as poly(2-phenylpropyl)(n-hexyl)silane [$R^1=R^2$=H, $R^3$=n-hexyl] were prepared by Wurtz-type coupling reactions with Na using a sonochemical method. The high-intensity ultrasound provided the formation of high quality Na dispersion in toluene and its active surface which was important for the synthesis of polysilanes in Wurtz-type coupling reaction was freshly and continuously regenerated during the process. The polysilanes products were mixtures of high molecular weight polymers with $\={M}_W$ of ∼$10^6$ and low molecular weight polymers with $\={M}_W$ of ∼$10^3$. It was found that the formation of high molecular weight polymerr was greatly influenced by the substituents $R^3$, directly attached to Si. On the contrary, changes on substituents ($R^1, R^2$) gave no influences at all. Overall yields for polysilanes were 75-99% in general but high molecular weight polysilanes were obtained as a major product when substituent $R^3$ is n-hexyl group and low molecular weight polysilanes were obtained as a major product when substituent $R^3$ is cyclohexyl and 2-phenylethyl groups. Effects of reaction conditions to polysilane yields were investigated.

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A Study on PCP Adsorption in Various Paddy Soils of the Choongbook Area (충북지방(忠北地方) 답토양(沓土壤)에 대(對)한 PCP 흡착에 관한 연구(硏究))

  • Ok, Hwan-Suk;Lee, Jae-Koo
    • Applied Biological Chemistry
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    • v.15 no.3
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    • pp.229-240
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    • 1972
  • Not only in order to determine reasonable application amounts of PCP in terms of soil texture, but also to get basic data for fish-toxicity-free treatment by estimating fish toxicity, some aspects of PCP adsorption were observed taking various paddy soils with different physico-chemical characteristics in the Choongbook Area as samples. The results obtained are summarized as follows: 1. There was a positive correlation between PCP adsorption and clay contents, total nitrogen, organic matter, cation exchange capacity, exchangeable bases, and phosphorus absorption coefficients, respectively; whereas there was a negative one between PCP adsorption and pH. Although they were not significant, it was remarkable that there was a relatively large amount of correlation between PCP adsorption and clay contents, $H^+,\;Mg^{++}$, and CEC, respectively. 2. PCP adsorption in terms of soil texture was in the order of Clay>Loam>Sandy loam. 3. Although PCP adsorption in the $H_2O_2-treated$ soils decreased remarkably, it was not proportional to the humus contents. 4. The order of PCP adsorption in the exchangeable base-treated soils was H^+-exchanged soil>$K^+-soil$>$Na^+-soil$>$Ca^{++}-soil$>Mg^{++}-soil. 5. Langmuir's and Freundlich's adsorption isotherms were applicable to the PCP adsorption, and thereby were able to be calculated maximum adsortion amounts of PCP, bond energy, and the depths of adsorption layers. 6. Maximum adsorbed amounts of PCP were 212.14 mg/100gr in Clayey loam, 97.28 to 121.59mg/100gr in Loam, and 32.92 to 91.74mg/100gr in Sandy loam, respectively. 7. The depths of mixed layers of limiting application for fish-toxicity-free treatment were 0.88cm of the Jinchun soil, the shallowest and 4.29 cm of the Naesan-ri Sandy loam, the deepest.

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Effects of Soil Water Potential on the Moisture Injury of Rubus coreanus Miq. and Soil Properties (토양수분퍼텐셜이 복분자 습해와 토양특성에 미치는 영향)

  • Ahn, Byung-Koo;Kim, Kab-Cheol;Kim, Dae-Hyanf;Lee, Jin-Ho
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.2
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    • pp.168-175
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    • 2011
  • This study was conducted to examine the impacts of different soil water potentials on environmental soil properties related to the moisture injury of Korean raspberry (Rubus coreanus Miq.). Soil water potential in the plastic film house plots was differentiated from -5 to -40 kPa. Soils in the plots contained 5.6% of plant available water. Increasing soil water contents based on the changes in water potential increased soil pH and exchangeable $Ca^{2+}$ content and decreased exchangeable $K^+$ and total N contents. It also declined soil organic matter content at 9 days after water treatments. Relationship between water potential and soil water content was given as an exponential equation, y = 96.534 - 20.28In(x). In particular, when the water potential was higher than -20 kPa (27.5% of soil moisture content), it decreased chlorophyll content in the raspberry leaves, inhibited N uptake by the plant, and increased phosphorus content with increasing days after water treatment. Also, as the 7 days after water treatment at higher than -20 kPa of water potential, the root activity of the plant was significantly decreased, and trunk (top)/root (T/R) ratio of the plant markedly declined until 9 days after water supply. Carbohydrate contents in the raspberry plant leaves and roots at dormant stage were the lowest at -5 and -10 kPa of water potential plots, and it may cause winter injury to the plant.

A Study on Viscosity Reducing of Cement-Based Materials by Replacing Byproducts and Adding Low-Viscosity Type HRWR (산업부산물 치환 및 저점도형 고성능 감수제를 사용한 시멘트 계열 재료의 점도저하 방안 연구)

  • Son, Bae-Geun;Han, Dongyeop
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.353-358
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    • 2017
  • The aim of this research is providing a fundamental idea on reducing viscosity of high performance cementitous materials. In rheological aspect, to determine the fluidity of the cementitious materials, both yield stress and viscosity should be controlled. For the high performance cementitious materials with low water-to-binder ratio and high volume fraction, it was difficult to reduce the viscosity with superplasticizer while reducing yield stress was relatively easy. Hence, in this research, with the goal of reducing viscosity of the cementitious materials, both ways of reducing viscosity were suggested: achieving proper combination of powder conditions, and adding low-viscosity typed water reducer. First, by replacing various byproduct powders, specifically, raw coal ash and wasted limestone powder showed favorable results on reducing viscosity of the cement paste. Regarding the low viscosity typed superplasticizer, it showed a good performance on reducing viscosity comparing with generic superplasticizer. Therefore, based on the results of this research, it is expected to provide a fundamental idea on reducing viscosity of cementitious materials by various methods.

Optimized DSP Implementation of Audio Decoders for Digital Multimedia Broadcasting (디지털 방송용 오디오 디코더의 DSP 최적화 구현)

  • Park, Nam-In;Cho, Choong-Sang;Kim, Hong-Kook
    • Journal of Broadcast Engineering
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    • v.13 no.4
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    • pp.452-462
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    • 2008
  • In this paper, we address issues associated with the real-time implementation of the MPEG-1/2 Layer-II (or MUSICAM) and MPEG-4 ER-BSAC decoders for Digital Multimedia Broadcasting (DMB) on TMS320C64x+ that is a fixed-point DSP processor with a clock speed of 330 MHz. To achieve the real-time requirement, they should be optimized in different steps as follows. First of all, a C-code level optimization is performed by sharing the memory, adjusting data types, and unrolling loops. Next, an algorithm level optimization is carried out such as the reconfiguration of bitstream reading, the modification of synthesis filtering, and the rearrangement of the window coefficients for synthesis filtering. In addition, the C-code of a synthesis filtering module of the MPEG-1/2 Layer-II decoder is rewritten by using the linear assembly programming technique. This is because the synthesis filtering module requires the most processing time among all processing modules of the decoder. In order to show how the real-time implementation works, we obtain the percentage of the processing time for decoding and calculate a RMS value between the decoded audio signals by the reference MPEG decoder and its DSP version implemented in this paper. As a result, it is shown that the percentages of the processing time for the MPEG-1/2 Layer-II and MPEG-4 ER-BSAC decoders occupy less than 3% and 11% of the DSP clock cycles, respectively, and the RMS values of the MPEG-1/2 Layer-II and MPEG-4 ER-BSAC decoders implemented in this paper all satisfy the criterion of -77.01 dB which is defined by the MPEG standards.

Survey on the Green house Flower Soil Chemicophysical Properties and Amount of Fertilizers and Soil Amendment Applications (시설화훼(施設花卉) 재배지(栽培地) 토양(土壤)의 이화학성(理化學性)과 화학비료(化學肥料) 및 토양개량제(土壤改良制) 시용량(施用量) 조사(調査))

  • Hwang, Ki-Sung;Noh, Dae-Chul;Ho, Qyo-Soon
    • Korean Journal of Environmental Agriculture
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    • v.17 no.2
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    • pp.132-135
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    • 1998
  • This study was conducted to obtain basic information for soil improvement in flower crop cultivating greenhouse soil through survey on the chemical and physical properties of greenhouse soils. Total of 85 Flowcultivating farms were surveyed and analysis was done on the soil characteristics, amounts of chemical fertilizer and soil amendmentuse. The result are as follows: In soil properties of flower cultivating greenhousees, silt clay loam was 51%and 68% of the surveyed soils had good drainage condition. Ground water table was over 90-120cm which was optimum range for flower cultivation. Flower cultivating farms had problem with accumulation of fertility. Nitrate nitrogen was accumulated in Gypsophila paniculate farms and available phosphorus, and exchangeable postassium were significantly higher in greenhouse soils about 2 times than in open field soil. Application amount of chemical feltilizers in greenhouses were nitrate 211,phosphorus 135, and potassium 132kg/ha, respectively. Amount of organic matter used in greenhouse were high in order of cattle manure> compost> organic fertilizer> poultry manure> swine manure and their application amounts were69, 103, 32, 20, and 43 MT/ha, respectively.

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