• Advances in concrete construction
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• 제3권1호
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• pp.71-90
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• 2015

In order to investigate the feasibility and advantage of tuff used as pozzolan in cement-based composite, the representative specimens of tuff were collected, and their chemical compositions, proportion of vitreous phase, mineral species, and rock structure were measured by chemical composition analysis, petrographic analysis, and XRD. Pozzolanic activity strength index of tuff was tested by the ratio of the compression strength of the tuff/cement mortar to that of a control cement mortar. Pozzolanic reaction degree, and the contents of CH and bond water in the tuff/cement paste were determined by selective hydrochloric acid dissolution, and DSC-TG, respectively. The tuffs were demonstrated to be qualified supplementary binding material in cement-based composite according to relevant standards. The tuffs possessed abundant $SiO_2+Al_2O_3$ on chemical composition and plentiful content of amorphous phase on rock texture. The pozzolanic reaction degrees of the tuffs in the tuff/cement pastes were gradually increased with prolongation of curing time. The consistency of CH consumption and pozzolanic reaction degree was revealed. Variation of the pozzolanic reaction degree was enhanced with the bond water content and relationship between them appeared to satisfy an approximating linear law. The fitting linear regression equation can be applied to mutual conversion between pozzolanic reaction degree and bond water content.

• 한국산학기술학회논문지
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• 제18권7호
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• pp.73-83
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• 2017

본 연구는 반추동물 사료로서 한국에서 생산된 부존사료자원 15종의 화학적 조성, 소화율 그리고 에너지 가를 평가하기 위하여 실시하였다. 반추위 그리고 십이지장 캐뉼라가 장착된 거세한우 3두(평균체중 $520{\pm}20.20kg$)를 개별 계류식우사에 공시한 후 14일의 순치기간과 3일간의 시험기간을 두었다. 실험 방법으로는 화학조성 분석법, in situ 나일론백과 모바일백 방법을 이용하였다. 사료 내 화학적 조성을 분석한 결과, 엿밥, 깻묵, 장유박 및 두유박의 조단백질 함량은 30% 이상이었다. In situ 나일론백을 이용한 사료의 분해 특성을 분석한 결과, 비트펄프, 맥주박, 커피박, 엿밥, 수수겨, 임자박, 라면박 및 두유박의 반추위 미분해 단백질 함량은 50% 이상이었다. In situ 모바일백을 이용한 사료 내 가소화 영양소총량(TDN)의 분석은 비트펄프, 맥주박, 막걸리박, 수수겨, 깻묵, 라면박, 미강, 장유박, 비지, 두유박 및 밀기울이 50% 이상인 것으로 관찰되었다. 요약하자면, 상기 부존사료자원은 배합사료 또는 조사료를 대체할 수 있는 훌륭한 사료자원으로서의 높은 잠재적 가치를 가지고 있음을 시사하고 있다. 따라서 본 연구에서 얻은 부존사료자원의 화학적 조성, 소화율 및 에너지 가를 반추동물 섬유질배합사료 제조를 위한 기초 자료로 활용하고 이를 통해 사료효율 향상, 사료비용 절감 및 환경오염 감소에 기여하고자 한다.

• 보존과학회지
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• 제18권
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• pp.75-88
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• 2006

경상남도 진해시 두동리가마터 출토 백자를 중심으로 물리 화학적 분석, 미세구조관찰을 실시하여 경질과 연질백자의 특성을 과학적으로 고찰해보았다. 물리적 특성은 연질백자가 높은 흡수율과 기공률을 갖는 것을 확인하였다. 화학적 조성은 태토와 유약의 지역적 특성은 나타났으나 경질과 연질의 구분은 확인되지 않았다. 미세구조는 물리적 특성으로 확인되는 경질과 연질의 차이를 가시적으로 확인할 수 있다. 경질백자는 기공의 형태가 둥글고 유리질화된 장석과 같은 광물이 관찰되나 연질백자는 기공도 부정형으로 분포정도가 매우 크며 유리질화된 입자를 확인할 수 없다. 이와같은 분석 결과에서 두동리의 경질과 연질백자는 화학적 조성 및 번조조건에 따라 나타나는 차이보다는 물리적 특성이 크게 좌우하는 것으로 확인된다. 그러나 물리적 특성에 따른 사용 원료는 제작된 지역에 따라 가마별로 차이를 보일 수 있으므로 다양한 비교 연구가 필요하다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.196-200
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• 2005

단일액체추진제 하이드라진 소형로켓엔진의 이론성능해석을 위한 추진제 연소화합물의 화학평형조성 계산모델이 간략히 제시된다. 성능해석결과는 1 lbf급 추력기의 성능평가 시험결과와 암모니아 몰분율의 관점에서 비교, 분석되고, 노즐팽창비와 추진제 주입압력에 따른 화학평형 조성 및 평균분자량 등이 추가로 제시된다. 이론해석은 단일액체추진제 중 대형급 로켓엔진의 설계변수 도출의 일환으로 시도된다.

• Korean Chemical Engineering Research
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• 제57권6호
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• pp.883-890
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• 2019

Two-phase flow near the wellbore in volatile oil reservoirs causes complications in well test analysis. In this study, the flow behavior of volatile oil reservoirs below the bubble-point pressure and the potential of radial composite model for interpretation of two-phase well test in volatile oil reservoirs was investigated. A radial composite model was used for two-phase well test analysis. A new procedure was developed to interpret well test data and estimate the radius of the two-phase region. The changes in fluid composition near the wellbore during drawdown test were found to increase the saturation pressure, which affects the saturation profile during build-up. Well test results showed that the radial composite method is a powerful tool for well test characterization and estimation of reservoir parameters. The proposed procedure was able to estimate the reservoir parameters and radius of the two-phase region with acceptable accuracy.

• 한국지반환경공학회 논문집
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• 제3권2호
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• pp.49-60
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• 2002

퇴적암의 풍화특성을 파악하기 위해서는 풍화과정을 지배하는 암석의 광물조성과 화학성분에 대한 연구가 필요하다. 본 논문에서는 풍화정도에 따른 퇴적암의 특성을 고찰하기 위해서 대구지역에 분포하고 있는 퇴적암을 채취하여 화학 및 광물성분 분석과 물리 및 역학특성 시험을 실시하였다. 화학적풍화지수와 감열감량, 흡수율과 일축압축강도, 풍화지수와 일축압축강도가 좋은 상관관계를 나타내었으며 모암에 함유된 $A_2O_3$, CaO, $Na_2O$, $K_2O$, MgO 등의 화학성분과 조장석(Albite, Ab), 백운모(Muscovite, Ms), 마그네타이트(Magenetite, Mt)등의 광물성분이 풍화와 밀접한 관계가 있었다. 이 시험결과를 토대로 하여 퇴적암에 적용할 수 있는 정량적인 풍화도판정법의 적용성을 제시하자고 하였다.

• 동아시아식생활학회지
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• 제14권6호
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• pp.576-581
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• 2004

This study was carried out to evaluate the sensory evaluation of the muffins with mulberry leaf powder as well as their chemical characteristics. The muffins were prepared by adding 0%, 1 %, 2% and 3% mulberry leaf powder to the recipe. As a result of the sensory evaluations, the color, flavor and texture of the muffins of 2% mulberry leaf powder were found to be much better than those of the other groups. In the chemical composition analysis, increasing the mulberry leaf powder led to a significant increase in the content of crude protein, moisture and crude ash, while crude fat was significantly decreased. As the ratio of mulberry leaf powder increased, Ca, Mg, Fe and Zn in the muffins increased proportionally (p<0.05). The lightness value, the redness value and the yellowness value decreased with the increase of mulberry leaves powder content. In a texture analyser test, hardness and cohesiveness decreased as the ratio of mulberry leaf powder increased. The adhesiveness of the muffins with 2% mulberry leaf powder was the strongest of all.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.56-61
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• 1997

Lead zirconate titanate (PZT) thin fills were deposited onto the Pt/Ti/SiO2/Si substrate by the pulsed laser deposition with the second harmonic wavelength (532 nm) of Nd:YAG laser. In order to determine the optimum conditions for the film deposition, the phase of the films were investigated as functions of ambient oxygen pressure, substrate temperature, and laser fluence. Also the chemical composition analysis was conducted for the PZT films deposited under various ambient oxygen pressure. When the distance between substrate and bulk PZT target is set to 20 mm, the optimum conditions have been determined to be 3 torr of oxygen pressure, 1.5 J/cm2 of laser fluence, and 823-848(±10) K range of substrate temperature. At these conditions, perovskite phase PZT films were obtained on platinized silicon. The chemical composition of the films is very similar to that of PZT bulk target. The physical structure of the deposited films analyzed by scanning electron microscopy shows a columnar morphology perpendicular to the substrate surface. Capacitance-Voltage hysteresis loop measurements show also a typical characteristics of ferroelectric thin film. The dielectric constant is found to be 528 for the 0.48 μm thickness of PZT thin film.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.600-603
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• 1995

A series of samples in the Sm1-xSrxCoO3-y(x=0.00, 0.25, 0.50, 0.75 and 1.00) system has been prepared at 1200 ℃ under ambient atmosphere. The X-ray diffraction patterns of the samples with x=0.00 and 0.25 are indexed with orthorhombic symmetry like GdFeO3 and x=0.50 appears to be perfectly cubic. In the tetragonal system (x=0.75), the structure is similar to that of SrCoO2.80. The composition of x=1.00, SrCoO2.52, shows the brownmillerite-type structure. The reduced lattice volume is increased with x value in this system. The chemical analysis shows the τ value (the amount of the Co4+ ions in the system) is maximized at the composition of x=0.50. Nonstoichiometric chemical formulas are determined by the x, τ and y values. The electrical conductivity has been measured in the temperature range of 78 to 1000 K. The activation energy is minimum for those of x=0.25 and x=0.50 with metallic behavior. First-order semiconductor-to-metal transition of SmCoO3 is not observed. Instead, a broad, high-order semiconductor-to-metal transition is observed. In general, the effective magnetic moment is increased with increasing τ values at low temperature. At high temperature, the magnetic moment is maximum for that of x=0.00. The 3d-electrons are collective and give ferromagnetism in x=0.50.

• Macromolecular Research
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• 제11권2호
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• pp.128-131
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• 2003

Triblock copolymers of poly(dimethylsiloxane) (PDMS) middle block and degradable polyester end blocks were synthesized by the ring open polymerization initialed by alcohol groups of PDMS. Surface composition of the triblock copolymers is measured by angle-dependent electron spectroscopy for chemical analysis. The PDMS blocks are segregated in the topmost surface region and constituted up to 90 mol% of the surface, even though the overall bulk PDMS concentrations of the block copolymers is 6% or less. This result suggests that the bulk property of degradable polyesters is essentially unchanged due to the high surface segregation of PDMS.