• Economic and Environmental Geology
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• v.28 no.3
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• pp.259-269
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• 1995

Column leaching tests were conducted using fresh and weathered pulverised fuel ash of some 17 and 40 years old from two major British power plants, with deionised water and simulated synthetic industrial leachate. The former was to see the leaching behaviour of weathered ash and the latter was to see if the formation of secondary products from water and PFA interaction and ameliorating effect in removing metals from industrial leachates. Fresh PFA liberates elevated concentrations of surface-enriched inorganics, including Ca, Na, K, B, $Cr_{total}$, Li Mo, Se and $SO^{2-}_4$. This might indicate their association with the surface of PFA particles. In the column leaching tests using weathered ash and deionised water, elements are not readily leached but are released more slowly, showing relatively constant concentrations. For the case of weathered ash, some readily soluble surface-enriched elements appears to have been liberated in their early stage of leaching and the liberation of glass associated elements are thought to be more important function in controlling the element concentration. The result from column leaching tests exceed for a number of elements when compared with various Water Standards and suggests the leachate from PFA disposal mound needs dilution to achieve target concentrations. PF A shows element retention effect for many elements, including B, Fe, Zn, Hg, Ni, Li and Mo, in the order of fresh Drax ash > weathered Drax ash > Weathered Meaford ash in retaining capacity. Geochemical modelling using a computer program WATEQ4F reveals some solubility controlling secondary solid products. These include $CaSO_4{\cdot}2H_2O$ for Ca, $Al(OH)_3$ for Al and $Fe(OH)_3$ for Fe.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.2
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• pp.159-166
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• 1999

This study was conducted to investigate the effects of application of the dolomite particle and the shell powder on soil characteristics, dry matter yield and nutritive value of forages in loam soil at the experimental field of National Livestock Research Institute, Suwon, from 1994 to 1996. Application treatments were control, lime, dolomite 0.5, 2.0, 4.0mm, and shell powder in mixed pasture. Rate of dust occurrence was greatly decreased according to dolomite application and the dissolving rate in soil was highest in shell powder application among treatments. Although there was no significant difference, average dry matter yield of forages for 3 years was slightly increased with the application of lime, shell powder, dolomite 0.5mm, 4.0mm, 2.0mm and control in order. Both Ca and Mg contents of forages were no differences among treatments in 1994. However, all treatments were higher than those of control in 1995. And K and Na contents of forages were no differences among treatments. Lime requirement was greatly increased from 2,630 to 6,150kg per ha with the lapse of time. Although soil hardness was optimum level at first, it was likely to become hard little by little after treatments. Solid phase of soil was lowered a little except for control. Organic matter and available $P_2O_5$ contents of soil were highest in shell powder application among treatments, and K, Ca and Mg contents of soil were no differences among treatments. Ca content was increased a little in 1995, but decreased a little in 1996 compared to that of soil before treatments in 1994. AIso, Mg content was lowered than that of soil before experiment in 1995 and 1996. The results demonstrated that use of dolomite and shell powder as lime substitutes could be reduced dust problem and coast pollution as well as soil improvement. Therefore, it is desirable to apply the dolomite and the shell powder every 3 years in loam soil.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.452-452
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• 2014

블랑켓 일차벽이나 디버터와 같은 핵융합로 플라즈마 대향부품은 플라즈마로부터 입사되는 중성자 및 입자들을 차폐하여 구조물을 보호하고, 발생열을 에너지로 변환하기 위해 냉각재를 활용한 열제거 기능을 담당한다. 특히, 고속중성자와 입사 열부하 및 여러 입자들로부터 블랑켓 및 내부 구조물을 보호하기 위해 차폐체와 구조물로 구성된다. 세계적으로 차폐체로서는 텅스텐 혹은 텅스텐 합금, 구조물용 재료로는 저방사화 Ferritic Martensitic (FM) 강이 유력한 후보재료로 개발, 연구 중에 있다. 국내에서는 국제핵융합로(ITER) 사업을 통해 고온등방가압(HIP, Hot Isostatic Pressing)을 이용한 이종금속간 접합기술과 한국형 저방사화 고온구조재료인 ARAA (Advanced Reduced Activation Alloy)가 개발되고 있으며, 이를 활용한 설계, 접합법 개발, 제작목업의 건전성 평가 등이 수행되고 있다. 한국원자력연구원에서는 핵융합 기초사업의 일환으로 전북대와 공동으로 수행 중인 건전성 평가체계 개발을 위해, 기 개발된 접합법을 활용한 $45mm(H){\times}45mm(W){\times}2mm(T)$의 W/FM강 목업을 제작한 바 있으며, 이를 국내 구축된 고열부하 시험 장비인 KoHLT-EB (Electron Beam)를 활용한 고열부하 인가 건전성 평가시험을 준비 중에 있다. 이종금속간 접합 특성은 기계적 평가를 위한 파괴시험을 통해 검증, 이를 활용한 목업이 제작되었으며, 제작된 목업에 대한 초음파를 이용한 접합면의 비파괴 검사를 통해 결함이 없음을 확인하였다. 최종적으로 실제 사용되는 핵융합 운전조건과 유사 혹은 가혹한 조건에서 고열부하를 인가하여, 그 건전성을 평가가 이루어질 것이다. 고열부하 시험을 위해서는 냉각조건, 인가 열부하, 수명평가를 통한 반복 고열부하 인가 횟수 등이 사전에 결정되어야 한다. 이를 위해 상업용 열수력, 구조해석 코드인 ANSYS-CFX와 -mechanical을 이용한 시험조건 모의 및 수명 평가가 수행되었다. 구축 장비의 냉각계통을 고려하여 냉각수의 온도 및 속도는 $25^{\circ}C$, 0.15 kg/sec로, 열부하는 0.5 및 $1.0MW/m^2$에 대해 모의를 수행하였다. 정상상태 시 텅스텐의 최대 온도는 각 열부하 조건에 따라 $285.3^{\circ}C$와 $546.8^{\circ}C$였으며, 이에 도달하는 시간을 구하기 위해 천이해석을 수행하였고, 이를 통해 30초에 최대온도 95 %이상의 정상상태 온도에 도달함을 확인하였다. 또한, 목업의 초기 온도에 도달하는 냉각시간도 동일한 천이해석을 통해 30초로 가능함을 확인하였고, 최종 시험 조건을 30초 가열, 30초 냉각으로 결정하였다. 결정된 반복 열부하 인가 조건에서 이종금속 접합체가 받는 다른 열팽창 정도에 따른 응력을 계산하여 목업의 수명을 도출하였고, 이를 시험해야 할 반복 횟수로 결정하였다. 각 열부하 조건에 따른 온도조건을 ANSYS-mechanical 코드를 활용하여 열팽창과 이에 따른 접합면의 응력분포로 계산하였다. 0.5 및 $1.0MW/m^2$에 대해, 목업이 받는 최대 응력은 334.3 MPa와 588.0 MPa 였으며, 이 때 텅스텐과 FM강이 받는 strain을 도출하여 물성치로 알려진 cycle to failure 값을 도출하였다. 열부하에서 예상되는 수명은 0.5 및 $1.0MW/m^2$에 대해, 100,000 사이클 이상과 2,655 사이클로 계산되었으며, 시간적 제약을 고려 최종 평가는 $1.0MW/m^2$에 대해, 3,000사이클 정도의 실험을 통해 그 수명까지 접합건전성이 유지되는 지 실험을 통해 평가할 예정이다.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.185-195
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• 2012

Due to the high reduction and sorption capacity as well as the large specific surface area, nanosized mackinawite (FeS) is useful in reductively transforming chlorinated organic pollutants and sequestering toxic metals and metalloids. Due to the dynamic nature in its colloid stability, however, nanosized FeS may be washed out with the groundwater flow or result in aquifer clogging via particle aggregation. Thus, these nanoparticles should be modified such as to be built into permeable reactive barriers. This study employed coating methods in efforts to facilitate the installation of permeable reactive barriers of nanosized mackinawite. In applying the methods, nanosized mackinawite was coated on non-treated silica sand (NTS) and chemically treated silica sand (CTS). For both silica sands, the maximum coating of mackinawite occurred around pH 5.4, the condition of which was governed by (1) the solubility of mackinawite and (2) the surface charge of both silica and mackinawite. Under this pH condition, the maximum coating by NTS and CTS were found to be 0.101 mmol FeS/g and 0.043 mmol FeS/g respectively, with such elevated coatings by NTS likely linked with impurities (e.g., iron oxides) on its surface. Arsenite sorption experiments were performed under anoxic conditions using uncoated silica sands and those coated with mackinawite at the optimal pH to compare their reactivity. At pH 7, the relative sorption efficiency between uncoated NTS and coated NTS changed with the initial concentration of arsenite. At the lower initial concentration, uncoated NTS showed the higher sorption efficiency, whereas at the higher concentration, coated NTS exhibited the higher sorption efficiency. This could be attributed to different sorption mechanisms as a function of arsenite concentration: the surface complexation of arsenite with the iron oxide impurity on silica sand at the low concentration and the precipitation as arsenic sulfides by reaction with mackinawite coating at the high concentration. Compared to coated NTS, coated CTS showed the lower arsenite removal at pH 7 due to its relatively lower mackinawite coating. Taken together, our results indicate that NTS is a more effective material than CTS for the coating of nanosized mackinawite.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.81-87
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• 1979

In order to observe the lasting effect of NK-compound mineral fertilizer and organic compound fertilizer including Myweon organic liquid fertilizer, a pot experiment was conducted with rice (Oriza Sativa) variety: Nong Back. These fertilizers were applied as basal and the same amount of urea form of nitrogen was top dressed about a month after transplanting, July seventh, 1977. Results obtained are as follows; 1. The lasting effect of various fertilizers were laid in following decreasing order; Myweon liquid < Organic compound fertilizer (Myweon coop. made) > NK-compound fertilizer (Chosun coop. made) Single fertilizer. It was considered that organic matter served as microbial feed and lead a temporary fixation of available plant nutrients in the soil, and the reduced surface area of the compound fertilizers slowed down the availability of the fertilizers. 2. The fertilizer showing greater lasting effect produced more panicles per hill and less grains per panicle than the fertilizers showing less lasting effect, and brought low maturity, which resulted in low paddy yield the paddy producing efficiency of nitrogen absorbed by straw was also low in the former fertilizers. Such advanced effect of the former fertilizer was considered to be related with the variety of early maturity and unseasonable topdressing of fertilizer which made at the maximum tillering stage. 3. For the production of Japonica type paddy with heavy fertilization which may required to depress the early growth a little and promote the late growth, it might be necessary to develop slow releasing fertilizers such as single fertilizer formulated to a large grains or compound fertilizer containing organic matter. 4. If the nitrogen content of paddy, Nong Back, far excess 0.64 or 0.65% and reaches 0.68% or above, the yield of the variety seemed to be decreased remarkbly through the low maturity rate and thousand grain weight.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.498-513
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• 2007

Since it was reported that incipient enamel caries can be recovered, previous studies have quantitatively evaluated that enamel artificial caries have been, remineralized with fluoride showing simultaneously the increase of width of surface layer and the decrease of width of the body of legion. There is, however, little report which showed that remineralization could occur without fluoride. In addition, the observations on the change of hydroxyapatite crystals also have been scarcely seen. In this study, enamel caries in intact premolars or molars was induced by using lactic acidulated buffering solutions over 2 days. Then decalcified specimens were remineralized by seven groups of solutions using different degree of saturation(0.212, 0.239, 0.301, 0.355) and different pH(5.0, 5.5, 6.0) over 10 days. A qualitative comparison to changes of hydroxyapatite crystals after fracturing teeth was made under SEM(scanning electron microscopy) and AFM(atomic force microscopy). The results were as follows: 1. The size of hydroxyapatite crystals in demineralized area was smaller than the normal ones. While the space among crystals was expanded, it was observed that crystals are arranged irregularly. 2. In remineralized enamel area, the enlarged crystals with various shape were observed when the crystals were fused and new small crystals in intercrystalline spaces were deposited. 3. Group 3 and 4 with higher degree of saturation at same pH showed the formation of large clusters by aggregation of small crystals from the surface layer to the lesion body than group 1 and 2 with relatively low degree of saturation at same pH did. Especially group 4 showed complete remineralization to the body of lesions. Group 5 and 6 with lower pH at similar degree of saturation showed remineralization to the body of lesions while group 7 didn't show it. Unlike in Group 3 and 4, Group 5 and 6 showed that each particle was densely distributed with clear appearance rather than crystals form clusters together.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06b
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• pp.219-222
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• 1996

수열법은 밀폐용기중에서 10$0^{\circ}C$이상의 가열, 가압된 수용액이 반응에 관여하는 것으로써, 수정, CaCO3, AlPO4, GaPO4 등과 같은 단결정의 육성 뿐만 아니라 균일분산계로부터 균일한 결정성의 미립자 합성에도 폭넓게 이용되고 있다. 세라믹분말의 합성에 있어서, 이 방법은 특히 형상, 입자크기의 제어가 용이할 뿐만 아니라 고상법, 졸-겔법, 공침법에서와 같은 열처리, 분쇄과정이 필요없기 때문에 고순도의 초미립자를 얻을 수 있는 장점이 있다. 근년 미국, 일본에서는 수열법을 이용한 유전, 압전체 등 세라믹분말의 일부가 공업적인 규모로 대량 생산되고 있다. 그러나 이에 대한 국내 기술은 아직 초기단계에 이르고 있는 실정이다. 따라서 본 연구실에서는 수열법에 의한 단결정 육성 (예; 자수정, CaCO3, AlPO4, GaPO4, KTP, Emerald 등), 박막제조 (예; GaP, PbTiO3, BaTiO3 등), 정제 (고령토, 장석, 도석 등), 원석처리 (진주, 인공 emerald, 비취 등) 그리고 각종 세라믹분말의 합성 등과 같은 다양한 기반기술의 축적과 동시에 공업화에 대응한 수열장치를 위하여 반응용기의 대형화, 엄밀한 밀폐방식, 실용적인 수열조건 등을 개발해 오고 있다. 본 발표에서는 현재까지의 연구개발 내용 중에서 결정성 미립자에 관련한 세라믹분말의 합성에 대한 일부의 결과들을 보고한다. 일반적으로 수열장치는 전기로, 반응용기, 온도 및 압력제어계 등을 기본으로 하고 있으며 시판용의 대부분이 교반기가 부착된 수직형 (vertical type)이다. 이와 같은 방식에 있어서는 엄밀한 밀폐가 곤란, 반응온도의 한계성 (25$0^{\circ}C$ 이하), 증진율의 한계성 (소량생산) 등과 같은 점이 있기 때문에 본 연구실에서는 개폐식 전기로내에 엄밀한 밀폐가 가능한 수평식(horizontal type)의 반응용기를 채택한 뒤 이를 회전 또는 시이소(seesaw)식으로 움직일 수 있도록 하여 연속공정화, 온도구배의 자율조절 그리고 보다 저온에서도 인위적인 이온의 확산을 효율적으로 유도할 수 있도록 하였다. 이와 같은 방식은 기존의 방식과 비교하여 반응용기 내에 응집현상과 미반응물이 존재하지 않으며 또한 단분산으로 결정성 미립자를 대량적으로 얻을 수 있는 장점이 있었다. 다음은 이상과 같이 본 연구실에서 자체 개발한 수열장치를 이용하여 PbTiO3, (Pb,La)TiO3Mn, BaTiO3, ZnSiO4:Mn, CaWO4 등과 같은 세라믹분말에 대한 합성 실험의 결과이다. 압전성, 초전성이 우수한 PbTiO3 및 (Pb,La)TiO3:Mn 분말의 수열합성은 PbO, TiO2, La2O3 등의 분말을 출발원료로 하여 합성도도 25$0^{\circ}C$부근의 알카리성 용액중에서 결정성 PbTiO3 및 (Pb,La)TiO3:Mn 미립자를 단상으로 얻었으며 입자의 형상 및 크기는 합성온도와 수열용매의 종류에 의존하였다. 유전체로서 폭넓게 응용되고 있는 BaTiO3 분말은 Ba(OH)2.8H2O, TiO2와 같은 최적의 출발원료를 선택함으로써 15$0^{\circ}C$ 부근의 저온영역에서도 용이하게 합성할 수 있었다. 특히 본 연구에서는 수용성인 Ba(OH)2.8H2O를 사용함으로써 host-guest적인 반응을 유도시키는데 있어 물의 가장 실용적이고 효과적인 수열용매임도 알았다. ZnSiO4:Mn, CaWO4, MgWO4와 같은 형광체 분말은 공업적으로 고상반응 또는 습식법에 의해 얻어지고 있으나 이들 방법에 있어서는 분쇄공정으로 인한 형광특성의 저하와 같은 문제점이 있다. 따라서 본 연구에서는 수열법을 이용하여 이들 화합물의 합성을 시도하였으며 그 결과 합성온도 30$0^{\circ}C$ 부근의 알칼리성 용액중에서 수열적으로 얻어짐을 알았다. 여기서의 합성분말을 이용하여 실제 조명램프로 제조한 결과 녹색, 청색 발광용 형광체로서 우수한 형광특성을 나타내었다. 천연에서 소량 산출되고 있는 고가의 (Li,Al)MnO2(OH)2:Co 분말은 도자기의 전사지용 청색안료로써 이용되고 있다. 본 연구실에서는 LiOH.H2O, Al(OH)3, MnO2 등의 분말을 출발원료로 하고 24$0^{\circ}C$ 온도 부근 그리고 물을 수열용매로 하여 천연산에 필적하는 (Li,Al)MnO2(OH)2:Co 분말을 인공적으로 합성하였다.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.483-490
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• 2009

The aims of this study were to evaluate the removal efficiency for various pollutants in urban storm runoff by a filtration device, and to determine design parameters depending on filter media properties. Appropriate selection of filter media will affect the size and life time of the filtration device. Sets of column tests were performed in order to evaluate the removal efficiency by perlite and a synthetic resin. An investigation of surface properties including CEC (cation exchange capacity) and zeta-potential suggested that the perlite had a superior adsorption capability for cationic pollutants. TCODcr and turbidity were analyzed to investigate the removal characteristic of particulate pollutant. In both columns, the particles in the collected storm runoff was almost completely capture with a small EBCT (empty bed contact time) of 2.5 minutes. Complete clogging at the EBCT of 2.5 minutes occurred after 630 minutes in the perlite column and 810 minutes in the resin column. The removal efficiency of TCODcr and turbidity at the EBCT of 2.5 minutes decreased to below 70% due to an wall effect. The removal efficiency for dissolved pollutant (SCODcr) was negligible due to the insufficient contact time for adsorption. The removal of heavy metals (Cu, Zn, Pb) was mostly ascribed to the filtration of particles containing metals, since the relationship between CEC and the removal efficiency was not apparent. The result of this study would be valuable for the application of filtration device to control of urban storm runoff.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.47-56
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• 2007

In this research, the effects of the gravel content on the liquefaction behavior for both of the isotropically and $K_0-anisotropically$ consolidated gravel-sand mixtures are investigated. for this purpose, the cyclic triaxial tests for the specimens with the same relative density (Dr=40%) and variations of gravel content were performed. On the other hand, a series of undrained cyclic triaxial tests were carried out on the isotropically consolidated gravel-sand mixtures with the same void ratio (e=0.7) and from 0% to 30% gravel contents. Void ratios of gravel-sand mixtures with the same relative density (Dr=40%) are found to decrease significantly with the increase of the gravel content from 0% to about 70% and increase thereafter. But the void ratio of the sand matrix among the gravel skeleton increases with the increase of the gravel contents. Test results are as follows : for the isotropically consolidated specimen with 40% of relative density and low gavel contents (GC=0%, 20%, 40%), pore water pressure development and axial strain behavior during undrained cyclic loading show similar behavior to those of the loose sand because of high void ratio, and the specimens with high gravel content (70%) both pore pressure and strata behaviors are similar to those of dense sand. And the isotropically consolidated specimens with the same void ratio (e=0.7) and higher gravel contents show the same behavior of pore water pressure and axial strain as that of the loose sand, but for the lower gravel content this behavior shows similar behavior to that of dense sand. The liquefaction strength of the isotropically consolidated specimens with the same relative density increases with gravel content up to 70%, and the strength decreases with the increase of the gravel content at the same void ratio. Thus, it is confirmed that the liquefaction strength of the gravel-sand mixtures depends both on relative density and void ratio of the whole mixture rather than the relative density of the sand matrix filled among gravels. On the other hand, the behavior of pore water pressure and axial strain for the $K_0-anisotropically$ consolidated gravel-sand mixtures shows almost the same cyclic behavior of the sand with no stress reversal even with some stress reversal of the cyclic loading. Namely, even the stress reversal of about 10% of cyclic stress amplitude, the permanent strain with small cyclic strain increases rapidly with the number of cycles, and the initial liquefaction does not occur always with less than maximum pore water pressure ratio of 1.0. The liquefaction resistance increases with the gravel contents between 0% and 40%, but tends to decrease beyond 40% of gravel content. In conclusion, the cyclic behavior of gravel-sand mixtures depends on factors such as gravel content, void ratio, relative density and consolidation condition.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.113-123
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• 1996

This experiment was carried out to compare with the physico-chemical properties of granular fused magnesium phosphates which were two domestic products(Pungnong Biryo Industrial Co., LTD and Kyunggi Chemical Industrial Co., LTD) and a imported Chinese product. The changes of pH, distribution of particle size, disintegration in water and in soil, hardness in soil, chemical composition, and dissolution rates in water, in soil and in 2% citric acid solution were investigated. The changes in pH were bigger in Jungmun series(black volcanic soil), in the imported chinese product, and in Jungmun series with the larger quantities applied. The domestic products were lower in pH, calcium, alkalinity and 1/2N-HCl soluble silicate than the Chinese product but total(Aqua regia) soluble phosphate, 2% citric acid soluble phosphate, 1/2N-HCl soluble and 2% citric acid soluble magnesium, and 2% citric acid soluble manganese concentration were similar among the domestic products and the imported product. In particle sizes, Chinese product was the biggest, Kyunggi product was the next, and Pungnong product was the smallest. The changes of disintegration rate in water and in soil were smaller in Pungnong and Kyunggi products at the early days of dissolution, and there were decreased with the order of Kyunggi product> Chinese product> Pungnong product at the latter days. The hardness of the products in soil was the strongest in Kyunggi product, the next was Pungnong product and Chinese product was the weakest so as to hardly measurable. The changing dissolution rates of 2% citric acid soluble phosphate concentration of granular fused magnesium phosphate products were the highest in Kyunggi product and the lowest in Pungnong product at the early days, the three products were dissolved over 90% within 50 days, and there were no clear difference among the products after 70 days of dissolution. The dissolution rates of 2% citric acid soluble phosphate concentration of granular fused magnesium phosphate products in soil were the highest in Pungnong product and Chinese product was the lowest, but they were less than 60% in 100 days of dissolution.