• International Journal of Oral Biology
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• v.42 no.4
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• pp.197-201
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• 2017

A novel method for the detection of hydrogen peroxide in aqueous solution was developed via reaction between $H_2O_2$, trivalent titanium ion ($Ti^{3+}$) and 4-(2-thiazolylazo) resorcinol (TAR), resulting in a ternary complex with a maximum UV absorbance at 530 nm. The CE detection of $H_2O_2$ was fast, sensitive and cost-effective without pretreatment procedures. $H_2O_2$ was detected within 15 min at 1 to $100{\mu}M$ range with the lowest detection limit at $1.0{\mu}M$. Under the optimized CE conditions, the concentration of $H_2O_2$ in coffee or tea extract was quantitatively determined. Our results show that CE detection of the ternary complex of $H_2O_2-Ti^{3+}$-TAR has potential applications for the detection of $H_2O_2$ in aqueous sources.

• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.991-1003
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• 1990

A precipitation method, one of the most effective liquid phase reaction methods, was adopted in order to prepare high-tech Al2O3/ZrO2 composite ceramics. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent, various types of metal hydroxides were obtained by single precipitation(series A) and co-precipitation(series B) method at the pH condition between 7 and 11. Fine Al2O3-ZrO2 powders were prepared at optimum calcination condition and the effects of ZrO2 on microstructures and mechanical properties of Al2O3 were investigated. The composition of Al2O3/ZrO2 composites wax fixed as Al2O3-15 v/o ZrO2(＋3m/o Y2O3). ZrO2 limited the grain growth of Al2O3 and increased grain size homogeneity of Al2O3 more effectively than MgO.Flexural strength values in Al2O3 and Al2O3/ZrO2 composites were 340-430 MPa and 540-820 MPa, respectively, and the effect of strength improvement showed 20-50% by adding ZrO2 to Al2O3. Fracture toughness of Al2O3/ZrO2 composites was improved by stress-induced phase transformation of tetragonal ZrO2 and toughening effect by microcrack was not observed. Also, ZrO2 particles located at Al2O3 grain junction contributed to toughening, while spherical ZrO2 particles located within Al2O3 grain did not contribute to toughening. Weibull moduli of Al2O3 ceramics and Al2O3/ZrO2 composites of series A and series B were 4.34, 5.17 and 9.06, respectively. Above 0.5 of failure probability, strength values in Al2O3 ceramics and Al2O3/ZrO3 composites of series A and series B were above 400 MPa, 700 MPa and 650 MPa, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.106-106
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• 1999

반도체 소자가 소브마이크론 이하로 집적화 되어감에 따라, RC 신호 지연 및 간섭 현상, 전력 소비의 증가 문제가 심각하게 대두되고 있다. 이러한 문제를 개선하기 위해서는, 현재 층간 절연막으로 상용화되어 있는 SiO2 박막을 대체할 저유전율 박막의 개발이 필수적이며, 많은 연구자들이 여러 가지 새로운 유기물질과 무기물질은 제안하고 있다. 반도체 공정상의 적합성을 고려할 때, 이들 여러물질 중에서 알킬기를 함유한 SiO2 박막(이하 'Si-O-C-H 박막'으로 표기)에 많은 관심이 집중되고 있다. Si-O-C-H 박막은 알킬기에 의해 형성된 나노 스케일의 기공에 의해 작은 유전율을 가지게 된다. 따라서, 박막내의 알킬기의 함유량이 많을수록 보다 작은 유전율을 얻을 수 있다. 그러나 과다한 알킬기의 함유는 Si-O-C-H 박막의 열적 특성을 열화시키는 부정적인 효과도 있다. 본 연구에서는 bis-trimethylsilylmethane(BTMSM, H9C3-Si-CH2-Si-C3H9) precursor를 이용하여 Si-O-C-H 박막을 증착하였다. BTMSM precursor의 중요한 특징중 하나는, 두 실리콘 원자 사이에 Si-CH2 결합이 존재한다는 사실이다. Si-CH2 결합은 양쪽의 Si에 의해 강하게 결합되어 있어서, BTMSM precursor를 사용하여 Si-O-C-H 박막은 유전상수도 작을 뿐 아니라, 열적으로도 안정된 특성이 얻어질 것으로 기대된다. Si-O-C-H 박막의 열적 안정성을 평가하기 위하여, 고온 열처리 전후의 FT-IR 스펙트럼 분석과 C-V(capacitance-voltage) 측정에 의한 유전상수 변화를 살펴보았다. 또한 증착된 박막의 미세구조 및 step coverage 특성 관찰을 위하여 SEM(scanning electron microscopy) 및 TEM(transmission electron micfroscopy) 분석을 하였다. 변화하였으며 이는 포토루미네슨스의 변화의 원인으로 판단된다. 연구하였다. CeO2 와 Si 사이의 계면을 TEM 측정에 의해 분석하였고, Ce와 O의 화학적 조성비를 RBS에 의해 측정하였다. Si(100) 기판위에 증착된 CeO2 는 $600^{\circ}C$ 낮은 증착률에서 seed layer를 하지 않은 조건에서 CeO2 (200) 방향으로 우선 성장하였으며, Si(111) 기판 위의 CeO2 박막은 40$0^{\circ}C$ 높은 증착률에서 seed layer를 2분이상 한 조건에서 CeO2 (111) 방향으로 우선 성장하였다. TEM 분석에서 CeO2 와 Si 기판사이에서 계면에서 얇은 SiO2층이 형성되었으며, TED 분석은 Si(100) 과 Si(111) 위에 증착한 CeO2 박막이 각각 우선 방향성을 가진 다결정임을 보여주었다. C-V 곡선에서 나타난 Hysteresis는 CeO2 박막과 Si 사이의 결함때문이라고 사료된다.phology 관찰결과 Ge 함량이 높은 박막의 입계가 다결정 Si의 입계에 비해 훨씬 큰 것으로 나타났으며 근 값도 증가하는 것으로 나타났다. 포유동물 세포에 유전자 발현벡터로써 사용할 수 있음으로 post-genomics시대에 다양한 종류의 단백질 기능연구에 맡은 도움이 되리라 기대한다.다양한 기능을 가진 신소재 제조에 있다. 또한 경제적인 측면에서도 고부가 가치의 제품 개발에 따른 새로운 수요 창출과 수익률 향상, 기존의 기능성 안료를 나노(nano)화하여 나노 입자를 제조, 기존의 기능성 안료에 대한 비용 절감 효과등을 유도 할 수 있다. 역시 기술적인 측면에서도 특수소재 개발에 있어 최적의 나노 입자 제어기술 개발 및 나노입자를 기능성 소재로 사용하여 새로운 제품의 제조와 고압 기상 분사기술의 최적화에 의한 기능성 나노 입자 제조 기술을 확립하고 2차 오염 발생원인 유기계 항균제를 무기계 항균제로 대

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.102-108
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• 1997

ZrO2 powders stabilized with Y2O3 and CeO2 of various compositions were prepared by the coprecipitation of water-soluble ZrOCl2.8H2O, YCl3.6H2O and Ce(NO3)3.6H2O, and their compacts were pressurelessly sintered at 1400 and 150$0^{\circ}C$ for 2hrs in air. 2mol% Y2O3-ZrO3 showed the most superior strength (1003MPa) and microhardness (12.6GPa), while 10 mol%CeO2-ZrO2 had the hightest toughness (13.3 MPa.m1/2) after sintering at 140$0^{\circ}C$. The addition of Y2O3 into Y2O3-ZrO3 decreased mean grain size and increased strength and hardness but decrease toughness. On the other hand, the addition of CeO2 into Y2O3-ZrO2 enhanced the stability of tetragonal phase during low-temperature aging for a long time under hydrothermal atmosphere.

• Journal of IKEEE
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• v.25 no.1
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• pp.1-9
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• 2021

In this paper, a 4H-SiC UMOSFET was studied which is suitable for high voltage and high current applications. In general, SiO2 is a material most commonly used as a gate dielectric material in SiC MOSFETs. However, since the dielectric constant value is 2.5 times lower than 4H-SiC, it suffers a high electric field and has poor characteristics in the SiO2/SiC junction. Therefore, the static characteristics of a device with high-k material as a gate dielectric and a device with SiO2 were compared using TCAD simulation. The results show BV decreased, VTH decreased, gm increased, and Ron decreased. Especially when the temperature is 300K, the Ron of Al2O3 and HfO2 decreases by 66.29% and 69.49%. and at 600K, Ron decreases by 39.71% and 49.88%, respectively. Thus, Al2O3 and HfO2 are suitable as gate dielectric materials for high voltage SiC MOSFET.

• Journal of Acupuncture Research
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• v.17 no.3
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• pp.208-218
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• 2000

This study was undertaken to determine if Salviae Radix (SR) exerts protective effect against oxidant-induced inhibition of phosphate uptake in renal proximal tubular cells. Membrane transport function and cell death were evaluated by measuring phosphate uptake and trypan blue exclusion, respectively, in opossum kidney (OK) cells, an established proximal tubular cell line. $H_2O_2$ was used as a model oxidant. $H_2O_2$ inhibited the phosphate uptake in a dose-dependent manner over the concentration range of 0.1-0.5 mM. Similar fashion was observed in cell death. However, the phosphate uptake was more vulnerable to $H_2O_2$ than cell death, suggesting that $H_2O_2$-induced inhibition of phosphate uptake is not totally attributed to cell death. Decreasedphosphate uptake was associated with ATP depletion and inhibition of $Na^+$-pump activity as determined by direct inhibition of $N^+-K^+$-ATPase activity. When cells were treated with $H_2O_2$ in the presence of 0.05% SR, the inhibition of phosphate uptake and cell death induced by $H_2O_2$ was significantly attenuated. SR restored ATP depletion and decreased $Na^+-K^+$-ATPase activity, and this is likely responsible for the protective effect of SR on decreased phosphate uptake. The protective effect of SR was similar to the $H_2O_2$ scavenger catalase. SR reacts directly with $H_2O_2$ to reduce the effective concentration of the oxidant. The iron chelator deferoxamine prevented the inhibition of phosphate uptake and cell death induced by $H_2O_2$, suggesting that $H_2O_2$-induced cell injury is resulted from an iron-dependent mechanism. These results indicate that SR exerts the protective effect against $H_2O_2$-induced inhibition of phosphate uptake by reacting directly with $H_2O_2$ like the $H_2O_2$scavenger enzyme catalase, in OK cells. However, the underlying mechanism remains to be explored.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.466-472
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• 2012

Visible-light-responding photocatalysts, $N-TiO_2$, were prepared by nitrogen doping onto $TiO_2$. The crystalline structure and morphology, doping state of the prepared photocatalysts were characterized by XRD, FE-SEM, and XPS. The activity of the prepared photocatalysts was examined by the decomposition of methyleneblue. The prepared catalysts were anatase type and the crystallinity was increased with pH. The particle sizes of the prepared catalysts were 5.42, 5.99, 7.58 nm at pH 2.2, 4.7, 9.0, respectively. The particle sizes of the prepared catalysts were slightly increased with pH. The activity of the photocatalysts was directly proportional to the crystallinity of the catalysts. $N-TiO_2$ prepared by nitrogen doping onto $TiO_2$ showed activity under visible light. The doped nitrogen was located not in the lattice but on the surface.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.63-70
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• 2001

Sodium persulfate, prestogen W, prestogen EB, citric acid 및 thiourea의 첨가에 따른 $H_2O_2$ 표백 효과가 연구되었다. Sodium persulfate(1%), Prestogen EB(15.0%)를 $H_2O_2$ 활성제로 첨가하여 표백할 경우 기존 $H_2O_2$ 표백(86.0% ISO)보다 표백 펄프의 백색도가 2-3% ISO 더 증가하였다. $H_2O_2$ 표백 후 thiourea를 첨가하여 표백하는 산화-환원 연속표백(87.9% ISO)에서도 $H_2O_2$ 표백 후 FAS로 2단 표백(88.3% ISO)을 한 경우와 비슷한 백색도를 나타내었다. 한편 표백 펄프의 인장지수, 파열지수 그리고 인열지수는 기존 표백 또는 Prestogen EB를 첨가할 경우 높고 sodium persulfate 첨가에서 가장 낮았다. 산화-환원 연속 표백된 펄프의 강도도 기존 $H_2O_2$ 표백보다 미세하게 낮았다.

• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.126-129
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• 1988

Lithium bonded complexes with $H_2O$ molecule were investigated theoretically by varying the substituent of lithium compound as follows; LiH, LiLi, $LiCH_3,\;LiNH_2$, LiOH, LiF, and LiCl. Some hydrogen bonded complexes with $H_2O$ molecule were also investigated to be compared with lithium bonded analogues. Electron correlation effect on the structures and energies of lithium bond was also investigated through MP2 and MP4 corrections. Unlike hydrogen bond with $H_2O$ molecule, lithium bonded complexes with $H_2O$ molecule were found to be interacting linearly with $H_2O$ molecule. Electron correlation effect was very small for lithium bonded complexes. The lithium bond energies were found to be less affected by the choice of substituent of lithium compound.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.281-285
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• 2000