• 한국도로학회논문집
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• 제20권3호
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• pp.65-73
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• 2018

PURPOSES : In this study, the propriety of expansion joint spacing of airport concrete pavement was examined by using weather and material characteristics. METHODS : A finite element model for simulating airport concrete pavement was developed and blowup occurrence due to temperature increase was analyzed. The critical temperature causing the expansion of concrete slab and blow up at the expansion joint was calculated according to the initial vertical displacement at the joint. The amount of expansion that can occur in the concrete slab for 20 years of design life was calculated by summing the expansion and contraction by temperature, alkali-silica reaction, and drying shrinkage. The effective expansion of pavement section between adjacent expansion joints was calculated by subtracting the effective width of expansion joint from the summation of the expansion of the pavement section. The temperature change causing the effective expansion of pavement section was also calculated. The effective expansion equivalent temperature change was compared to the critical temperature, which causes the blowup, according to expansion joint spacing to verify the propriety of expansion joint applied to the airport concrete pavement. RESULTS : When an initial vertical displacement of the expansion joint was 3mm or less, the blowup never occurred for 300m of joint spacing which is used in Korean airports currently. But, there was a risk of blow-up when an initial vertical displacement of the expansion joint was 5mm or more due to the weather or material characteristics. CONCLUSIONS : It was confirmed that the intial vertical displacement at the expansion joint could be managed below 3mm from the previous research results. Accordingly it was concluded that the 300m of current expansion joint spacing of Korean airports could be used without blowup by controling the alkali-silica reaction below its allowable limit.

• Current Photovoltaic Research
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• 제6권2호
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• pp.56-61
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• 2018

In this study, CIGS absorber layers were deposited on low-alkali glass and sodalime glass substrates and potasium floride (KF) of various thicknesses was supplied at an elevated temperature after the CIGS growth. The effect of KF post-deposition treatment on the two types of substrates was extremely different. On the low-alkali substrate, the open-circuit voltage (Voc) was improved but the fill-factor (FF) degradation was severe, whereas the sodalime substrate showed Voc deterioration and FF improvement. In the case of supplying 20 nm of KF on both substrates, the efficiency gain of 0.3~1.1%p was obtained. With increasing the KF thickness, a small protrusion-like microstructure developed on the surface of the absorber layer, and the microstructures that were not removed in the subsequent process were found to be the main cause of the FF loss.

• 한국광물학회지
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• 제21권3호
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• pp.261-269
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• 2008

몽골 서부 할잔-부룩테이 알칼리 복합체에서 산출되는 페그마타이트는 Nb-Y-Zr-F의 부화가 특징적인 NYF 유형의 함희유금속 페그마타이트이다. 이들 함희유금속 페그마타이트는 할잔-부룩테이 섬장암 및 알칼리 장석 화강암의 분화물로서 알칼리 화강암류에 비해 십 배 이상의 희유금속이 농집되어 있다. 할잔-부룩테이 함희유금속 페그마타이트의 경제성은 페그마타이트맥의 연장성 및 국부적 품위 변화에 의해 좌우될 것으로 생각된다.

• Computers and Concrete
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• 제7권2호
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• pp.169-190
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• 2010

The focus of this research effort was characterization of the flexural and tensile properties of a specific ultra-high-strength, fiber-reinforced concrete material. The material exhibited a mean unconfined compressive strength of approximately 140 MPa and was reinforced with short, randomly distributed alkali resistant glass fibers. As a part of the study, coupled experimental, analytical and numerical investigations were performed. Flexural and direct tension tests were first conducted to experimentally characterize material behavior. Following experimentation, a micromechanically-based analytical model was utilized to calculate the material's tensile failure response, which was compared to the experimental results. Lastly, to investigate the relationship between the tensile failure and flexural response, a numerical analysis of the flexural experiments was performed utilizing the experimentally developed tensile failure function. Results of the experimental, analytical and numerical investigations are presented herein.

• 상하수도학회지
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• 제30권5호
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• pp.571-577
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• 2016

Phosphorus is an essential and irreplaceable element for all living organisms and its resource is limited. Significant amount of used phosphorus is collected in sewage treatment plant as sludge. Sludge ash after incineration contains about 10% of phosphorus in dry mass basis, which is comparable to phosphate rocks, and it is an important source of phosphorus recovery. Acid and alkali were used to leach phosphorus from sludge ash and compared for their leaching kinetics and performance. Phosphorus leaching by NaOH was fast and 0.2 N and 2 N NaOH leached 49% and 56% of the total phosphorus in the sludge ash at the L/S ratio of 100. Phosphorus leaching by sulphuric acid and hydrochloric were very fast and most of the phosphorus was leached in 5 minutes. In case of sulphuric acid 95% of the total phosphorus in the sludge ash was leached by 0.2 N at the L/S ratio of 100 and 93% was leached by 1 N at the L/S ratio of 10. 1 N hydrochloric acid leached 99% of the total phosphorus at the L/S ratio of 10. The results showed acids were more effective than alkali for phosphorus leaching from sludge ash and hydrochloric acid leached more phosphorus than sulphuric acid.

• 한국지구과학회지
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• 제43권6호
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• pp.737-748
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• 2022

본 연구에서는 울릉도 알봉조면안산암 용암돔에서 관찰되는 장석 반정의 안티라파키비 조직에 대하여 점분석 및 X-ray element mapping 면분석(EPMA 분석)을 실시하여 장석들의 성분을 파악하였다. 알봉조면안산암에서 반정으로 산출되는 사장석은 비토우나이트에서 라브라도라이트 및 안데신에, 미반정과 석기에서 래쓰로 산출되는 것은 안데신에서 올리고클레이스에 해당한다. 사장석 반정과 미반정을 감싸 얇은 띠(누대)를 이루는 알칼리장석은 안오쏘클레이스에서 새니딘에 해당한다. 뚜렷한 누대구조를 보이는 사장석 반정은 반정 중앙부에서 가장자리 쪽으로 감에 따라 누대의 An 함량이 비토우나이트에서 라브라도라이트 또는 라브라도라이트에서 안데신으로 감소하는 정상 누대구조를 나타내며, 반정의 가장자리는 알칼리장석으로 둘러싸여 안티라파키비 조직을 나타낸다. 전형적인 안티라파키비 조직을 나타내는 장석 반정에 대하여 X-ray 면분석을 실시한 결과, 누대가 뚜렷한 성분 조성의 차이를 나타내는 정상 누대구조를 잘 보여주며, 그 가장자리는 알칼리장석으로 감싸면서 안티라파키비 조직을 나타낸다. 알봉조면안산암에서 나타나는 장석의 안티라파키비 조직은 조면안산암 마그마보다 더 고철질인 마그마 속에서 이미 결정화된 사장석 반정과 미반정이 알봉조면안산암 마그마와 혼합되면서 사장석 반정과 미반정 주위를 알칼리장석이 결정화되어 맨틀링하면서 형성되었을 것이다.

• 대한환경공학회지
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• 제39권11호
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• pp.626-633
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• 2017

본 연구에서는 전기 제강로 분진(EAFD)으로부터 고 순도의 아연회수를 위한 산 습식법 중 알칼리 금속 및 염화물(Na, K, Cl) 제거를 위한 적정 수 세척공정의 운영조건에 대해 조사하였다. 서로 다른 성상을 가지는 두 종류의 EAFD 시료를 대상으로 원소분석, XRD, 입도 분석 등의 물리화학적 특성을 분석하였고, 세척액의 pH, 세척시간, 고액비(mL/g) 및 세척반복횟수 등에 따른 알칼리 금속 및 염화물의 세척효율(%)을 비교하였다. 연구 결과, EAFD 내 알칼리 금속과 염화물은 고액비 3, 세척시간>30, pH 10~11의 조건에서 아연과 철의 손실을 최소화하면서(<~0.1%) 효과적으로 제거할 수 있었으며, 1회 세척시 Na-78%, K-76%, Cl >99%의 세척효율을 보였다. Na와 K는 3회 반복 세척 시 각각 97%, 89%까지 제거 가능하였다. 두 종류의 EAFD 혼합(1:1)시료를 대상으로 시료 용량을 늘려(10배) 수행한 실험 결과에서도 세척액의 최종 pH 10~11에서 Zn의 손실 없이 Na, K, Cl 등을 효과적으로 제거 가능함을 확인하였다.

• 암석학회지
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• 제5권1호
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• pp.66-83
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• 1996

이 연구는 알칼리 화산도로 특정지워진 제주도의 동부 성읍리, 서부 한림읍 이사돌 그리고 한경면고산리 지구내 해안에 분포하는 수매의 솔리아이트에 대한 암석기재, 광물화학, 주성분 및 미량성분 원소의 화학자료를 보고한다. 이들은 주로 반상조직인 알칼리암류에 비해 세립질이며, 주상 혹은 침상의 사장석 ($An_{61-46}$)과 사방휘석(브론자이트) 및 감람석($Fo_{78-67}$)이 입자간 조직을이룬다. 특징적으로 사방휘석이 반자형의 반정 혹은 미반정으로 산출되고, 두 유형의 단사휘석(피저나이트와 보통 휘석)은 석기 광물로만 산출한다. 이들 솔리아이트는 노옴 석영을 가지며, 주성분 원소의 변화 범위는 좁다(SiO2=51.0-52.5 wt%; Mg#=54-60). 주성분 원소와 전이금속 원소의 변화경향이 알칼리암ㄹ와 두드러진 것은 동일 마그마의 분화로 솔리아이트와 알칼리암의 관계를 설명할 수 없다는 것을 시사한다. 한편, $K_2O$, Rb, Ba, Nb, La들 간의 비는 솔리아이트와 알칼리암이 유사한 반면, P, Y, Yb 등 석류석과 친화적인 원소와 이 원소들 간의 비는 솔리아이트가 알칼리암보다 크다. 이러한 미량원소 특징은 제주도의 솔리아이트와 알칼리 현무암류는 동질 기원이나 부분용융정도가 다른 모마그마로부터 유래되었음을 시사한다.

• 자원환경지질
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• 제23권3호
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• pp.329-342
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• 1990

The purpose of this study is to clarify the nature of the differentiation and petrogenesis of igneous rocks in comparison with experimental results based on petrological and geochemical criteria. Study area is composed of the Precambrian granitic gneiss complex, Triassic meladiorite and biotite granodiorite, Jurassic biotite granite, and Cretaceous quartz porphyry. According to the data of EPMA, the clinopyroxene and orthopyroxene of meladiorite come under salite and hypersthene, respectively. Such results suggests that meladiorite is incipient differentiated products of basic magma under slow cooling condition. The petrochemical data of variation diagram of major element oxides vs. silica and of trace element oxide vs. silica, AMF triangle diagram and trace elements suggests that igneous rocks of study area are plutonic rocks belong to calc alkali rock series of the source of comagma intruded-emplaced in the order of meladiorite, biotite granodiorite and biotite granite by fractional crystallization of magma.

• 한국지구과학회지
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• 제36권5호
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• pp.447-459
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• 2015

Dok island comprises Pliocene volcanic products such as a series of volcanoclastic rocks and lavas ranging in composition from alkali basalts, and trachyandesites to trachytes. Compositional variation of the basaltic rocks can be attributed to fractional crystallization of olivine, clinopyroxene, plagioclase, and magnetite. Chemical variations among the trachyandesites are caused by fractionation of clinopyroxene, plagioclase, and magnetite with minor amphibole, while trachytes are controlled mainly by feldspar fractionation. Incompatible element abundance ratios and chondrite normalized LREE/HREE ratios (e.g., (La/Yb)c: 24.8 to 32.8 for basalts, 15.6 to 31.2 for trachyandesites) suggest that the origins of the basalts and trachyandesites involve both different degrees of partial melting and subsequent fractional crystallization processes. Trace element ratios of the basalts from Dok island are characterized by high Ba/Nb, La/Nb, Ba/Th and Th/U and isotopic ratios (Tasumoto and Nakamura, 1991) that are similar to the EM 1 type of oceanic island basalts such as Gough and Tristan da Cunha basalts.