• 한국세라믹학회지
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• 제31권11호
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• pp.1265-1270
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• 1994

Ultra-fine hydroxyapatite powder were synthesized by the hydrothermal reaction at 10 atm, 3 hrs of Ca(OH)2 suspension with (NH4)2HPO4 solution, and were characterized sintering behavior. Sintered bodies of hydroxyapatite powders which synthesized by hydrothermal reaction method has less weight loss, less sintering shrinkage and superior mechanical property, and was more dense than sintered bodies of hydroxyapatite powder which synthesized by wet method. Sintered bodies were hydroxyapatite single phase. When soack in Ringer's solution for 2 weeks, hydroxyapatite powders preserved hydroxyapatite and sintered body absorbed trace of Ca2+ ion with soaked time.

• 한국세라믹학회지
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• 제37권7호
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• pp.721-725
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• 2000

In this study, the dispersion stability of nano-sized CeO2 particles, synthesized by hydrothermal method in aqueous was evaluated from observing the surface potential behavior of CeO2 particle synthesized by solid state reaction. The isoelectric point(IEP) of nano-sized CeO2 synthesized by hydrothermal synthesis was found to be pH 9 contrary to the isoelectric point of micro-sized CeO2 synthesized by solid state reaction at pH 6.7. IEP was shifted to pH 2.0 as the addition of D-3019 from 0.1 to 1.0 wt%. The surface potential of CeO2 particles synthesized by hydrothermal synthesis was reduced as the addition of B-1001 used as a binder without change of IEP because the absorption of B-1001 polymer on the CeO2 particles shifted the shear plane of CeO2 particles outward away from the surface. This surface potential behavior was well correlated with the dispersion stability of slurry.

• 한국세라믹학회지
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• 제50권6호
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• pp.434-438
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• 2013

Monodispersed 3Y-$ZrO_2$ spherical agglomerates were synthesized by thermal hydrolysis process followed by crystallization processes (hydrothermal treatment and calcination). The crystallization process affected the properties of the final particles, such as the primary particle size, the agglomeration state, and the fraction of $ZrO_2$ monoclinic phase. The hydrothermal treated spherical particles were porous microstructures (weak agglomerates) composed of small primary particles with a size of 14 nm, but the calcined spherical particles had a dense microstructure due to the hard aggregation between primary particles. While the calcined particles had a low green density due to the hard aggregation, hydrothermal treated ones were soft agglomerates and had a deflection point at 50 MPa due to the rearrangement of secondary spherical particles and the filling of the interstices with the primary particles. Finally, the green density of hydrothermally treated $ZrO_2$ particles was 58% at 200 MPa.

• Corrosion Science and Technology
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• 제8권3호
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• pp.103-109
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• 2009

An epoxy coating was designed to give a hydrophobic property on its surface by modifying it with three types of Amino Terminated Polydimethylsiloxane (ATP), and then effects of the modification on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified epoxy coating were examined using FT-IR spectroscopy, hydrothermal cyclic test, and impedance test. The surface of epoxy coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between epoxy and modifier by the modification. The phase separation tendency is more appreciable when modified by ATP with higher molecular weight ATP at higher content. Water transport behavior of the modified epoxy coating decreased more in that with higher hydrophobic surface property. The resistance to localized corrosion of the modified epoxy coated carbon steel was well agreed with its water transport behavior and hydrophobic tendency.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.53.1-53.1
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• 2011

Bioactive glass powders were synthesized by hydrothermal chemical route by the use of ultrasonic energy irradiation. We used sodalime, calcium nitrate tetra hydrate and di ammonium hydrogen phosphate as the precursor material to synthesize $SiO_2$ rich bio-active glass materials. The $SiO_2$ content was varied in the precursor mixture to 60, 52 and 45 mole%. Dense compacts were obtained by microwave sintering at $1,100^{\circ}C$. Mechanical properties were characterized for the fabricated dense bioactive glasses and were found to be comparable with conventional CaO-$SiO_2$-$Na_2O$-$P_2O_5$ bioactive glass. Detailed biocompatibility evaluation of the glass composition was investigated by in-vitro culture of MG-63 cell and mesenchyme stem cell. Cell adhesion behavior was investigated for both of the cell by one cell morphology for 30, 60 and 90 minutes. Cell proliferation behavior was investigated by culturing both of the cells for 1, 3 and 7 days and was found to be excellent. Both SEM and confocal laser scanning microscopy were used for the investigation. Western blot analysis was performed to evaluate the bimolecular level interaction and extent and rate of specific protein expression. The ability to form biological apatite in physiological condition was observed with simulated body fluid (SBF). In-vivo bone formation behavior was investigated after implanting the materials inside rabbit femur for 1 and 3 month. The bone formation behavior was excellent in all the bioglass compositions, specially the composition with 60% $SiO_2$ content showed most promising trend.

• 대한치과기공학회지
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• 제27권1호
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• pp.79-88
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• 2005

This study was performed to investigate the surface properties of electrochemically oxidized pure niobium by anodic oxide and hydrothermal treatment technique. Niobium specimens of $10\times10mm$ in dimension were polished sequentially from #600, #800, #1000 emery paper. The surface pure niobium specimens were anodized in an electrolytic solution that was dissolved calcium and phosphate in water. The electrolytic voltage was set in the range of 250 V and the current density was 10 $mA/cm^2$. The specimen was hydrothermal treated in high-pressure steam at 300$^{\circ}C$ for 2 hours using an autoclave. Then, specimens were immersed in the Hanks' solution with pH 7.4 at 37$^{\circ}C$ for 30 days. The surface of specimen was characterized by scanning electron microscope(SEM), energy dispersive X-ray microanalysis(EDX), potentiostat/galvanostat test, and cytotoxicity test. The results obtained was summarized as follows; According to the result of measuring corrosion behavior at 0.9% NaCl, corrosion resistance was improved more specimens treated with anodic oxide than in hydrothermal treated ones. The multi-porous oxide layer on surface treated through anodic oxidation showed a structure that fine pores overlap one another, and the early precipitation of apatite was observed on the surface of hydrothermal treated samples. According to the result of EDX after 30 days deposition in Hanks' solution, Ca/P was 1.69 in hydrothermal treated specimens. In MTT test, specimens treated through anodic oxidation and hydrothermal treated ones showed spectrophotometer similar to that of the control group. Thus no significant difference in cytotoxicity was observed (P>0.05).

• 센서학회지
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• 제20권5호
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• pp.294-299
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• 2011

$SnO_2$ nanoparticles were synthesized by a hydrothermal method and gas sensors were fabricated using nanoparticles to detect dimethyl methylphosphonate(DMMP) gas. The prepared $SnO_2$ nanoparticles exhibited a high response(72 at $500^{\circ}C$) to 5 ppm DMMP gas compared to commercial $SnO_2$ nanopowders, but their recovery was relatively poor. Various metals(Ni, Sb, Nb) were added to the $SnO_2$ nanoparticles to improve their recovery properties. The focus of this study was to investigate the effects of metal oxide additives on DMMP sensing behavior in $SnO_2$ nanoparticles.

• 방사성폐기물학회지
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• 제5권2호
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• pp.145-154
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• 2007

벤토나이트 완충재의 열수거동 실험에서는 고준위폐기물처분장 완충재로 유력하게 고려되고 있는 국산 벤토나이트를 대상으로 열수특성을 규명하고, 또 그 결과를 바탕으로 KRS 처분환경에서 벤토나이트 완충재의 장기건전성을 평가하였다. 실험결과, 벤토나이트 완충재의 열수반응은 주 구성광물인 스멕타이트의 일라이트화를 통해 진행되었으며, 온도, $K^+$농도, pH는 이러한 일라이트화에 중요한 열수반응인자 역할을 하였다. KRS 처분환경에 대한 국산벤토나이트 완충재의 장기건전성을 분석한 결과, 정상상태에서는 벤토나이트 완충재가 오랜 기간 동안 방벽재기능을 유지하였지만, 보수적인 조건에서는 약 $5{\times}10^4$년이 경과했을 때 벤토나이트 완충재를 구성하는 스멕타이트의 50%이상이 일라이트로 전환되어 방벽재로서의 팽윤능력을 상실할 수 있음을 예상할 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제49권3호
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• pp.213-225
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• 2021

본 논문에서는 열수 탄화(hydrothermal carbonization)에 의해 제조된 리그닌 하이드로차의 탄화 특성을 조사하였고, 근적외선 분광법과 부분 최소 제곱(partial least squares) 회귀를 이용하여 탄화 거동을 예측하기 위한 모델을 수립하였다. 온도 200℃에서 열수 탄화된 리그닌의 탄소 함량은 무처리 시료 보다 약 3 wt% 높았으며 가열 시간이 증가할수록 탄소 함량도 서서히 증가하는 경향이 나타났다. 열수 탄화는 리그닌을 더욱 탄소 집약적으로 변화시키고 마이크로 파티클을 제거하여 더욱 균질한 특성을 부여하였다. 근적외선 분광법과 부분 최소 제곱 회귀를 이용한 판별 및 예측 모델은 수열 탄화의 적용 여부를 완벽히 구분했으며 높은 정확도로 열수 탄화 리그닌의 탄소 함량을 예측하였다. 본 연구로부터 근적외선 분광법과 결합된 부분 최소 제곱 회귀 모델을 이용하여 열수 탄화에 의해 제조된 리그닌 하이드로차의 탄화 특성을 빠르고 비파괴적으로 예측할 수 있다는 것이 확인되었다.

• 청정기술
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• 제24권4호
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• pp.323-331
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• 2018

실험실 규모 기포 유동층 반응기를 이용한 하수 슬러지와 석탄 및 우드 펠렛의 혼소 실험 및 회분 분석을 통한 슬래깅 성향을 살펴보았다. 연료는 일반 건조 및 수열탄화를 통해 제작된 하수 슬러지와 아역청탄, 우드 펠렛이 적용되었다. 연소 실험은 당량비 및 산화제 유량, 초기 온도를 고정하고 2종의 하수 슬러지 연료와 석탄 또는 우드 펠렛을 발열량 기준 50 : 50 비율로 혼합한 총 4개의 조건에 대해 반응기 온도 및 배가스 조성을 측정하였다. 배가스 중 $NO_x$는 모든 조건에서 대부분 NO의 형태로 400 ~ 600 ppm 범위에서 측정되었다. $SO_2$는 원료 내 황 함량을 고려하면 하수 슬러지의 투입량이 큰 영향을 미쳤을 것으로 예상되는 가운데 수열탄화 연료가 일반 건조 연료에 비해 다소 낮은 경향을 보였다. 비산 회분 조성 분석 결과 하수 슬러지 연료가 슬래깅/파울링 가능성을 높일 것으로 생각되며, 수열탄화 연료가 일반 건조 연료에 비해 상대적으로 양호한 결과를 보일 것으로 예상되었다.