• 한국지반공학회논문집
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• 제35권11호
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• pp.75-95
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• 2019

본 연구에서는 사질토층을 지나 풍화암에 소켓된 매입 PHC말뚝에 대한 수치해석 결과를 분석하여 정리한 도표 또는 도해로부터 매입 PHC말뚝의 동원지지력을 구하는 방법을 제안하였다. 즉, 수치해석 결과인 하중-침하량 곡선에서 5% 직경에 해당하는 침하량에서 발현된 사질토층의 동원주면마찰력, 풍화암층의 동원주면마찰력과 동원선단지지력을 산정할 수 있는 표해 또는 도해를 제안하였다. 이때 허용압축지지력은 동원 지지력에 안전율 3.0을 적용하여 산정하였다. 사질토층을 지나 풍화암에 소켓된 매입 PHC말뚝의 허용압축지지력은 사질토층의 허용주면마찰력과 풍화암층의 허용주면마찰력 및 허용선단지지력을 합산하여 산정하는 것으로 제안하였고, 각 허용압축지지력 성분을 구할 수 있는 절차도 제시되어 있다. 본 연구에서 제안된 동원지지력 산정용 표해(또는 도해)를 사용할 경우, 적정 설계에서 PHC말뚝의 설계효율(D_E)은 85%로 나타났으며, 따라서 최적 설계에서는 PHC말뚝의 장기허용압축하중(P_all) 까지도 활용할 수 있는 것으로 나타났다. 그리고 PHC말뚝의 우수한 압축하중 지지 성능을 효과적으로 활용하기 위하여 지반의 허용압축지지력(Q_all)이 말뚝의 허용압축하중(P_all) 이상이 될 수 있도록 설계할 것을 권장하였다.

• 한국수산과학회지
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• 제53권5호
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• pp.681-687
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• 2020

Physicochemical properties of fucoidan and alginate extracted from Sargassium horneri were investigated. The alginates were extracted and purified via three different routes (CaCl₂, HCl and ethanol routes), and their rheological properties at various concentrations and temperatures were determined. The yield of fucoidan was 3.08%, and it was mainly composed of fucose and galactose. Fourier-transform infrared spectrum of fucoidan showed strong absorption band at 1,254 and 827 cm^-1 corresponding to the sulfate group. Flow behavior of the alginate solution was characterized using the power-law model. The consistency index increased with increasing concentrations. The sodium alginate solution (1.5%) exhibited Newtonian behavior when extracted via the CaCl₂ and HCl routes, while it exhibited pseudoplastic behavior when extracted via the ethanol route. The effect of temperature on the flow behavior was investigated in terms of the activation energy (E_a), which was obtained using the Arrhenius equation. The E_a value corresponding to the alginate solution decreased with increasing shear rates. The E_a values corresponding to the alginate solutions purified via the CaCl₂, HCl, and ethanol routes were 13.54-18.64 kJ/mol, 13.42-19.21 kJ/mol, and 9.51-10.67 kJ/mol, respectively. The low E_a values corresponding to the solutions extracted via the ethanol route suggest that the flow behavior does not depend significantly on temperature.

• 한국세라믹학회지
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• 제41권1호
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• pp.13-18
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• 2004

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrodes were prepared on ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) thin films by spin coating method using photosensitive sol-gel solution. Self-patterning technique of photosensitive sol-gel solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. Lanthanum(III) 2-methoxyethoxide, Stronitium diethoxide. Cobalu(II)2-methoxyethoxide were used as starting materials for LSCO electrode. UV irradiation on LSCO thin films lead to decrease solubility by M-O-M bond formation and the solubility difference allows us to obtain self-patternine. There was little composition change of the LSCO thin films between before leaching and after leaching in 2-methoxyethanol. The lowest resistivity of LSCO thin films deposited on $SiO_2$/Si substrate was $1.1{\times}10^{-2}{\Omega}cm$ when the thin film was ennealed at $740^{\circ}C$. The values of Pr/Ps and 2Pr of LSCO/SBT/Pt capacitor on the applied voltage of 5V were 0.51, 8.89 ${\mu}C/cm^2$, respectively.

• 초등상담연구
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• 제7권1호
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• pp.67-90
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• 2008

The purpose of this study was to examine the effects of solution focused group counseling program on peer relationship and school life adaption of elementary school children. The subjects in this study were the 4th graders at S Elementary School in Ansan, Gyeonggi-do. 20 students were selected through the preliminary test of peer relationship and school life adaption, that is to say, each 10 students of experimental group and control group. A solution focused group counseling program was provided by researcher to the experimental group in six sessions once or twice a week, 60 minutes each. but control group was not conducted for any program. In verifying of the program effects in this study, KOREAN SPSS/WIN(version 12.0) is used for statistical analysis. The major findings of this study are as follows: First, solution focused group counseling program has a positive effect on all parts of sub-factors of peer relationship except to union life between friends. Second, solution focused group counseling program has a effect on the school life adaption of elementary and its all parts of sub-factors except to school rules. As noted above, it is proved that solution focused group counseling program has a positive effect to improve parts of sub-factors of peer relationship and school life adaption. Accordingly, it is necessary to feel satisfaction and Qualitative improvement in peer relationship and help school life adaptation of elementary school children through solution focused group counseling program.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.41-42
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• 2011

The purpose of this study is not only fixation of carbon dioxide using the cement-saturated solution by wet carbonating reaction but also evaluate the possibility of storage technology of Carbon dioxide. wet carbonation is reaction of CO₂ injection by CO₂ reactor. As a result of experiment, the carbon dioxide is fixed, and high-purity Calcium Carbonate is eluted.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.71-72
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• 2012

The purpose of this study is not only fixation of carbon dioxide using the cement-Paste solution's calcium ion by wet carbonating reaction but also quantitatively evaluate the possibility of storage technology of Carbon dioxide. wet carbonation is reaction of CO₂ injection by CO₂ reactor. As a result of experiment, the carbon dioxide is fixed, and high-purity Calcium Carbonate is eluted.

• 한국의류산업학회지
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• 제4권1호
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• pp.86-91
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• 2002

To estimate dispersion stability of particles, suspending power and particle size were examined as functions of pHs, surfactants, electrolytes and ionic strengths using ${\alpha}-Fe_2O_3$ particle as the model of particulate soil. Suspending power and particle size were determined by UV-Vis spectrumeter and by light scattering using the polarization ratio method, respectively. The suspending power was relatively high with polyanion electrolytes and was low with neutral salts. The suspending power was biphasis, minimum pH 6~7, and the effect of surfactant on the suspending power was insignificant. Generally suspending power increased with decreasing the particle size governed aggregation of dispersed particles regardless of solution conditions. Hence the suspending power was inversely related to the particle size.

• 센서학회지
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• 제32권4호
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• pp.207-212
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• 2023

H₂S is a toxic and harmful gas, even at concentrations as low as hundreds of parts per million; thus, developing an H₂S sensor with excellent performance in terms of high response, good selectivity, and fast response time is important. In this study, an H₂S sensor with a high response and fast response time, consisting of a sensing material (SnO₂), an electrode, a temperature sensor, and a micro-heater, was developed using micro-electro-mechanical system technology. The developed H₂S sensor with a micro-heater (circular type) has excellent H₂S detection performance at low H₂S concentrations (0-10 ppm), with quick response time (<16 s) and recovery time (<65 s). Therefore, we expect that the developed H₂S sensor will be considered a promising candidate for protecting workers and the general population and for responding to tightened regulations.

• 대한토목학회논문집
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• 제42권2호
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• pp.163-170
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• 2022

본 연구에서는 다양한 TiO₂ 적용방법이 포러스 콘크리트의 질소산화물 제거성능 및 흡음특성에 미치는 영향을 조사하였다. 포러스 콘크리트 배합과정에서 TiO₂를 단순 혼입하는 방법, 바텀애쉬 골재에 TiO₂를 전처리하고 이를 이용하여 포러스 콘크리트를 제조하는 방법, 마지막으로 제조된 포러스 콘크리트에 TiO₂ 용액을 도포하는 방법으로 TiO₂ 적용 포러스 콘크리트를 제조하였다. 실험결과 TiO₂의 단순 혼입은 TiO₂의 함량이 증가함에 따라 압축강도를 감소시켰으며, 공극률은 증가시키는 것으로 관찰되었다. TiO₂ 함침 바텀애쉬 골재를 이용하는 경우 압축강도는 기존 포러스 콘크리트와 유사하지만 공극률이 감소하는 것으로 나타났다. 마지막으로 표면 도포 방법의 경우 공극률은 유사하였으나 강도가 증가하였다. 질소산화물 제거성능에서 TiO₂를 표면 도포한 샘플이 가장 높은 효율을 보였으며, TiO₂를 단순 혼입한 샘플들보다 바텀애쉬 골재에 전처리한 샘플에서 더 높은 질소산화물 제거성능이 관찰되었다. 흡음성능의 경우 TiO₂를 단순 혼입한 경우 공극률과의 상관관계를 확인할 수 있었지만, 다른 적용방법의 경우 일정한 경향이 발견되지는 않았다.

• 한국세라믹학회지
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• 제41권9호
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• pp.642-646
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• 2004

Na$_2$Si$_2$O$_{5}$ added to the solution affects the hydration of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ with calcium sulfate. The reaction between 4CaOㆍAl$_2$O$_3$ Fe$_2$O$_3$and CaSO$_4$ㆍ 2$H_2O$ decrease with increasing amount of Na$_2$Si$_2$O$_{5}$ in solution, owing to low hydraulic reactivity of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$by the adsorption of silicate ions on the surface of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles. The dissolution rate of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles deceased with the increase of the concentration of silicate ion in solution. When the 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ particles was hydrated in gypsum - Na$_2$Si$_2$O$_{5}$ solution, the hydration was retarded and the rate could not discriminate between formation of ettringite and that of monosulfate, and it stopped in high concentration of silicate ions. However, silicate ion did not any effect on the dissolution rate of gypsum.ypsum.