• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.699-710
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• 2006

Batch scale experiments to investigate the efficiency of the solidification process for metal mine tailing treatment were performed. Portland and MSG (micro silica pouting) cements were used as solidifier and three kinds of mine tailings (located at Gishi, Daeryang, and Aujeon mine) were mixed with cements to paste solidified matrices. Single axis com-pressible strengths of solidified matrices were measured and their heavy metal extraction ratios were calculated to investigate the solidification efficiency of solidified matrices created in experiments. Solidified matrices ($5cm{\times}5cm{\times}5cm$) were molded from the paste of tailing and cements at various conditions such as different tailing/cement ratio, cement/water ratio, and different cement or tailing types. Compressible strengths of solidified matrices after 7, 14, and 28 day cementation were measured and their strengths ranged from 1 to $2kgf/mm^2$, which were higher than Korean limit of compressible strength for the inside wall of the isolated landfill facility ($0.21kgf/mm^2$). Heavy metal extractions from intact tailings and powdered matrices by using the weak acidic solution were performed. As concentration of extraction solution for the powdered solidified matrix (Portland cement + Gishi tailing at 1:1 w.t. ratio) decreased down to 9.7 mg/L, which was one fifth of As extraction concentration for intact Gishi tailings. Pb extraction concentration of the solidified matrix also decreased to lower than one fourth of intact tailing extraction concentration. Heavy metal extraction batch experiments by using various pH conditions of solution were also performed to investigate the solidification efficiency reducing heavy metal extraction rate from the solidified matrix. With pH 1 and 13 of solution, Zn and Pb concentration of solution were over the groundwater tolerance limit, but at pH $1{\sim}13$ of solution, heavy metal concentrations dramatically decreased and were lower than the groundwater tolerance limit. While the solidified matrix was immerged Into very acidic or basic solution (pH 1 and 13), pH of solution changed to $9{\sim}10$ because of the buffering effect of the matrix. It was suggested that the continuous extraction of heavy metals from the solidified matrix is limited even in the extremely high or low pH of contact water. Results of experiments suggested that the solidification process by using Portland and MSG cements has a great possibility to treat heavy metal contaminated mine tailing.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.32-37
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• 2003

The amount of 4,500 drums of soil waste are temporarily stored in KAERI. In order to develop a technology for safe treatment of the soil waste, a number of tests were performed by applying cement and polymer as solidifier. Immobilization specimens were adequately made by mixing soil waste with cement or polymer Compressive strength and leaching tests were performed in order to see the fulfillment to standard of disposal following the storage. A compressive strength, about 5,300psi was obtained from both solidifiers of cement containing 40% of soil waste and polymer containing 60%. The obtained leaching index was larger than 11, which was satisfied with the relevant standard. It was shown that the integrity of the solidified waste much depends on homogenization in solidifying process and hardness of the specimen. Volume reduction of solidified waste with polymer was better than that of cement by 20%.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.60-70
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• 2003

The stability of various waste forms to meet waste acceptance criteria was evaluated by using standard test methods of U.S.A and France. Compressive strength of waste forms were above 176.03 kgf/$\textrm{cm}^2$(cement), 15 kgf/$\textrm{cm}^2$(paraffin). In the thermal cycling test, there were no any change in their feature and volume, the loss of weight was 6.15% on the average. In the immersion test for 120 days, the loss of weight of paraffin waste form was 8.85-5.14% pH=3.83. The G-Value of $H_2$ and $CH_4$ in paraffin wax at $10^8rads$ rads of exposure dose were 2.65, 0.016.

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.33-40
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• 2014

In this paper, mechanical and germination characteristics of stabilized dredged soils were investigated to recycle dredged soil in eco-friendly manner such as waterfront construction. Non sintering binder (NSB), which was developed by using interchemical reactions between slag, high-calcium fly ash, alkali activator on the dredged marine clay, was added to dredged soil. Ordinary portland cement was also used for the comparison of two binders. Experimental tests such as flow test and unconfined compressive test were carried out to evaluate characteristics of stabilized dredged soil. Leaching test, pH measure, vegetation germination test were also conducted to consider environmental applicability. The unconfined compressive tests shows that unconfined compressive strength (UCS) also increases with the increase of curing time and mixed ratio. UCS of NSB mixtures were higher than those of OPC mixtures. Germination tests showed that germination and sprouting date are better in NSB mixture than OPC mixture. It can be explained that germination decreased as pH and 7-day strength increased.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.355-365
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• 2015

This study examined the fluidity and strength properties, water resistance, durability, and freeze-thaw of cementless loess mortar using an eco-friendly hardening agent. The experimental result indicates that 28 days compressive and flexural strength of the loess mortar was increased regardless of the weathered granite soil and loess mixture ratio as the replacement ratio of the hardening agent increases. The strengths were significantly increased until 14 days regardless of the hardening agent, while the effect on the strengths increasement was relatively low after 14 days. Thus, the strength development of loess mortar concrete was found to be faster than that of the normal concrete. In addition, when the hardening agent of 10% was used, the average flexural strength was 1.7MPa which is insufficient compared to the 28-day flexural strength of 4.5MPa for the paving concrete. However, the flexural strengths of the loess mortar concrete using the hardening agents of 20% and 30% were 4.0MPa and 5.3MPa, respectively. Thus, the hardening agent need to be at least 20% so that the loess mortar can be used for paving concrete. The experiment for water resistance shows that the repeated absorption and dry reduced mass regardless of the mixing ratio of the loess. The maximum length change also decreased with increasing the substitution rate loess mixture ratio and the hardening agent. The result of the freeze-thaw resistance test indicates that the relative dynamic modulus of elasticity at 300 cycle freeze-thaw with the hardening agents of 20% and 30% were 75% and 79%, relatively. Thus, the hardening agent of at least 20% is required to obtain the relative dynamic modulus of elasticity of 60% for the loess mortar.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.274-279
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• 2007

본 논문은 MPEG2 다중화 방식을 이용한 고화질 이미지를 실시간으로 송수신하는 시스템을 제안한다. 송신 시스템은 카메라로부터 획득한 고화질 이미지와 GPS 장비로부터 획득한 위치정보를 MPEG2 TS 방식으로 변환하여 전송한다. 수신 시스템은 송신되는 MPEG2 TS data를 실시간으로 고화질 이미지와 위치정보로 추출한 후에 화면에 display한다. 본 논문에서는 오류 발생에 대한 회피 방법으로 고화질 이미지를 포함한 패킷을 단순히 중복적으로 전송하는 방법을 사용하였다. 이러한 방법은 신호의 왜곡 혹은 패킷 손실에 의해 발생되었던 오류들을 현저하게 줄여주었으나 한 장의 고화질 이미지에 대한 평균 처리시간을 증가하였다. 평균 처리 시간을 줄이기 위해 송신 시스템은 스레드를 이용한 전송 방법을 사용하였으며 이러한 방법의 사용은 스레드 기법을 사용하지 않았을 때보다 빠른 평균 처리시간을 측정할 수 있었다.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.33-43
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• 2002

Recently, as large constructions on the coast increase, an application of a surface layer stabilization method which is one of the improvement methods for dredged soft clay has increased. However, there are few studies about this. The purpose of this study is clarifying characteristics of ultra-soft marine clay and hardening agent. Also, it is verifying an optimal mixture ratio of hardening agent through the laboratory tests according to designed experiments and proving by statistical analysis and pilot tests. Laboratory tests were performed with proper hardening agent and test soil in accordance with the design of experiments. Regression equations between hardening agents materials and unconfined compressive strength were derived from the tests. The applicability of regression equations were also verified by pilot tests. From the test results, it was found that hardening agent materials(cement, slag, fly-ash, inorganic salts, arwin, gypsum etc.) have some effect upon compressive strength. The optimal mixture ratio which satisfies the required compressive strength was derived from the statistical analysis. The effect of ground improvement by cements and hardening agents was confirmed through the pilot tests. This study will suggest data for design or construction criteria of stabilization of surface layer on ultra-soft marine clay.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.49-56
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• 2010

In the pyroprocessing of spent nuclear fuels, LiCl-KCl waste salt containing radioactive rare earth chlorides are generated. The radioactive rare earth oxides are recovered by co-oxidative precipitation of rare earth elements. The powder phase of rare eath oxide waste must be immobilized to produce a monolithic wasteform suitable for storage and ultimate disposal. The immobilization of these waste developed in this study involves a solid state sintering of the waste with host borosilicate glass and zinc titanate based ceramic matrix(ZIT). And the rare-earth monazite which synthesised by reaction of ammonium di-hydrogen phosphate with the rare earth oxides waste, were immobilzed with the borosilicate glass. It is shown that the developed ZIT ceramic wasteform is highly resistant the leaching process, high density and thermal conductivity.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.278-283
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• 2005

Cement and paraffin waste form were prepared with a acid extraction method for the analysis of radionuclides generated from nuclear power plants. The acid extraction method was carried out with $HNO_3-HCl$ acid. At first, we compared the method with the microwave acid digestion method using SRM. The solutions of decomposed SRM were then analyzed by AAS and ICP-AES. The acid extraction method had shown good results as microwave acid digestion method. This method provided recovery values greater than $80\%$ for metallic elements.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.21-31
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• 2003

IAEA, FT-04-020, and ANS 16.1, standard leaching test methods, were evaluated comparatively with their test results. Leaching index of Co-60 and Cs-137 for all waste forms were above 6.0. Their leaching behavior were contrary according to the type of matrix and leachant. Leachability of Co in cement waste form was higher in simulated seawater than demi. water, and higher in demi. water in paraffin waste form. Leachability of Cs was contrary to Cs. Cumulative fraction leached of Co was higher such as IAEA＞ANS＞FT in cement waste form.