• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.786-789
• /
• 2005

The proper parameters in a twin roll strip casting are important to obtain the stabilization of the Mg sheet. What is examined in this paper is the quantitative relationships of the important control parameters such as the roll speed, height of pool region, outlet size of nozzle, solidification profile and the final point of solidification in a twin roll strip casting Unsteady conservation equations were used for transport phenomena in the pool region of a twin roll strip casting in order to predict a velocity, temperature distributions of fields and a solidification process of molten magnesium. The energy equation of cooling roll Is solved simultaneously with the conservation equations of molten magnesium In order to consider the heat transfer through the cooling roil. The finite difference method (2-D) and the finite element method (2-D) are used in the analysis of pool region and cooling roil to reduce computing time and to improve the accuracy of calculation respectively.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1998년도 추계학술발표회요약집
• /
• pp.295-295
• /
• 1998

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2002년도 추계총회 및 연구발표회 초록집
• /
• pp.200.1-200
• /
• 2002

• 한국건축시공학회지
• /
• 제1권2호
• /
• pp.146-153
• /
• 2001

Radical development has been made in the every field of our society for the past scores of year. Radical development of industry and lining environment has mass-produced various toxic wastes . Which comes to the fore as a serious environmental problem. The purpose of this is to suggest the optima mix design by studying the utility of a toxic waste, plated sludge as a building material and deciding the standards of quality and use of cement and evaluating the properties of mortar and concrete in which plated sludge mixed. From an experiment, compressive strength required high early strength cement or special cement. Watertightness proved to be excellent. Heavy metals, such as Cd, Pb, Cu came out below an environmental standard. Cr+6 exceeded an environmental standard under a steam curing, but came out below an environmental under a standard curing. The higher replacement rate was, the lower frost, fusion and resistance were. Thus, got better results above the goal by condition. It was possible that plated sludge was replaced and solidified to aggregate. Therefore, it is necessary to define the standards of quality on strength, replacement rate of wastes, water permeability, endurance in other to solidify plated sludge to concrete products.

• Environmental Engineering Research
• /
• 제10권6호
• /
• pp.294-305
• /
• 2005

The effectiveness of fly ash-, quicklime-, and quicklime-fly ash-based stabilization/solidification(S/S) in chromium(Cr) contaminated soils was investigated using modified semi-dynamic leaching tests. Artificial soil samples composed of kaolinite or montmorillonite contaminated with chromium nitrate(4000 mg $Cr^{3+}\;kg^{-1}$ of solid) were prepared and then subjected to S/S treatment using quicklime, fly ash, or quick lime-fly ash. The effectiveness of the treatment was evaluated by assessing the cumulative fraction of leached $Cr^{3+}$ as well as, by computing the effective diffusivity ($D_e$) and the leachability index (LX) of the treated samples. The reduction in $Cr^{3+}$ release for the untreated samples was more pronounced in the presence of montmorillonite, which was attributed to sorption. Treatment with quicklime, fly ash, or quick lime-fly ash was significantly effective in reducing $Cr^{3+}$ release most probably due to the formation of pozzolanic reaction products and $Cr(OH)_3$ precipitation. The most effective treatment was observed in montmorillonite-sand soil samples treated with quicklime-fly ash (99.8% removal). The mean $D_e$ decreased significantly and the mean LX was greater than 9 for all treated samples, indicating that the treated soils were acceptable for "controlled utilization". The mechanism controlling $Cr^{3+}$ leaching from all treated samples during the first 5 days appeared to be diffusion.

• Environmental Engineering Research
• /
• 제10권3호
• /
• pp.112-121
• /
• 2005

The effectiveness of quicklime-based stabilization/solidification (S/S) in immobilizing lead (Pb) was assessed by performing semi-dynamic leaching tests (ANS16.1). In order to simulate landfill leaching conditions, the ANS 16.1 test was modified by using 0.014 N acetic acid (pH = 3.25) instead of distilled water. Artificial soil samples as well as field soil samples contaminated with Pb were tested. The effectiveness of quicklime treatment was evaluated by determining diffusion coefficients ($D_e$) and leachability indices (LX). A model developed by de Groot and van der Sloat was used to elucidate the controlling Pb leaching mechanisms. Overall, upon quicklime treatment Pb leachability was significantly reduced in a]l of the samples tested. The mean LX values were higher than 9 for an artificial soil sample containing 30% kaolinite treated with 10% quicklime and for a field soil sample treated with 10% quicklime, which suggests that S/S treated soils can be considered acceptable for "controlled utilization". Moreover, quicklime treatment was more effective in artificially contaminated soil with high kaolinite content (30%), indicating the amount of clay plays an important role in the success of the treatment. The controlling Pb leaching mechanism was found to be diffusion, in all quicklime treated samples.

• 한국환경보건학회지
• /
• 제19권2호
• /
• pp.46-54
• /
• 1993

This study was carried out on the stabilized/solidified treatment for the reducing leachability of hazardous heavy metals copper, lead, chromium and cadmium in the hazardous sludge which treated to be unleached heavy metals by sodium diethyl dithiocarbamate. Cement matrix was analyzed for the leachability of 24 hrs and dynamic leaching test, structure and the optimum condition for the stabilization and solidification of the hazardous sludge. In 28 days of curing time the unconfined compressive strength was 21.5 kg/cm$^2$ at the ratio of portland cement (0.5)+fly ash (0.25) and 23.5 kg/cmz at the ratio of portland cement (0.5)+fly ash (0.25) + cake (0.25). High concentration of Pb, Cr and Cd in the sea water and Cu in the distilled water were leached at the dynamic leaching test. The concentration of leaching heavy metals for specimens which were tested 24 hrs were found low leachability with decreasing pH of leachant. According to dynamic leaching test, the low level of copper, lead, cadmium and chromium were leached in the cement matrix with sodium diethyl dithiocarbamate. But the effective diffusion coefficient of unleached cement matrix which was treated sodium diethyl dithiocarbamate was decreased above 2 times than that of cement matrix. The relation of leachant renewal period (Y) and cumulative fraction ion leached (X) was the following regression equations. Solidification with unleached agent. Y$_{Cu}$ = 1413752X + 247, Y$_{Pb}$ = 223501IX + 214, Y$_{Cr}$ = 8310601X - 472, Y$_{Cd}$ = 168787X + 1061 The structure of' solidified matrix with X-ray diffraction analysis was composed more Ca(OH)$_2$, Si, Mg(OH)$_2$ and Al in the unleached cement matrix than those in cement matrix.

• 한국지반환경공학회 논문집
• /
• 제7권5호
• /
• pp.49-55
• /
• 2006

국내 풍부하게 매장된 석회석에서 생산되는 생석회는 점성토의 안정화에 뛰어난 잠재성을 가지는데 생석회를 점성토의 안정화에 이용할 수 있다면 천연자원 이용측면에서도 장점을 가질 수 있다. 점성토의 안정화에 생석회를 이용하는 공법은 안정화에 필요한 생석회요구량의 결정과 생석회 함량에 따른 안정화의 정도가 우선적으로 평가되어야 한다. 본 실험에서는 성곡 및 부곡 지역의 점성토와 2종류의 점토광물- 카올리나이트계 및 몬모릴로나이트계 -에 대하여 ASTM C 977-92에 따라 안정화에 필요한 생석회요구량을 결정하였으며 아터버그실험 및 pH실험을 통하여 각 시료에 대하여 생석회첨가량을 변화시켜 고결화 정도를 평가하였다. 각 시료에 대하여 생석회첨가량과 양생기간을 변화시켜 개선여부도 평가하였다. 각 시료는 ASTM C 977-92에 따라 결정된 생석회량을 첨가함으로써 소성한계, 일축압축강도는 개선되었으며 pH값은 증가경향은 감소하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.417-421
• /
• 2003

The purpose of this paper is to study on the construction of roadbed with environmental friendly soil amendment agent. The special amendment agent used in this study is mainly composed of inorganic metal salts such as sodium chloride, magnesium chloride, potassium chloride, calcium chloride,, thus is friendly to the environment, and has a function of soil-cement-agent solidification. Various components of this agent weaken the negative function of humic acid and decompose humic acid itself. Then, the calcium cation of the cement can now be made contact directly to the soil surface. The project of local road demonstration of roadbed construction with special soil treatment agent was peformed in Northeast Thailand on August 1999 by the sponsor of Highway Department of Thailand. A series of field experiments including unconfined compressive strength were carried out to investigate the physical and mechanical characteristics of solidified roadbed treated by this solidifying agent. The results of this research showed that the roadbed using poor soil could be efficiently constructed by treatment of this amendment agent.

• 한국지반환경공학회 논문집
• /
• 제13권2호
• /
• pp.59-65
• /
• 2012

본 연구에서는 비소 오염 토양의 비소 처리를 위해 고형화/안정화 공법을 적용하였으며, 4가지 종류의 바인더(시멘트, 영가철(Zero Valent iron, ZVI), monosulfate와 ettringite(시멘트계 합성물질))를 이용하였다. 1 N HCl 용출법을 통해 비교한 결과 바인더 함유량 20%에서, 시멘트(71.41%) > monosulfate(47.45%) > ettringite(46.36%) > 영가철(33.08%)의 비소가 용출되었다. 또한, 시멘트에 첨가제(monosulfate, ettringite, calcium sulfoaluminate, CSA)를 혼합하여 바인더를 제작하여 비소 저감 능력을 평가하였다. 1N HCl 용출법을 통해 비교한 결과 3가지 혼합바인더 모두 혼합비 4:1에서 최대의 비소농도 저감효과를 나타냈으며, CSA(86.27%) > monosulfate(84.78%) > ettringite(84.71%) > 시멘트(71.41%)의 비소를 안정화하여 기존의 시멘트만 단독으로 사용했을 경우보다 더 높은 비소(As(V)) 저감 능력을 가지고 있는 것으로 평가된다.