• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.193-197
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• 2012

$Gd_{1-x}VO_4:{Eu_x}^{3+}$ red phosphors were synthesized with changing the concentration of $Eu^{3+}$ ion by using a solid-state reaction method. The crystal structure, surface morphology, and photoluminescence and photoluminescence excitation properties of the red phosphors were measured by using X-ray diffractometer, field emission-scanning electron microscopy, and florescence spectrometer, respectively. The XRD results showed that the main peak of all the phosphor powders occurs at (200) plane. As for the photoluminescence properties, the maximum excitation spectrum occurred at 306 nm due to the charge transfer band from ${VO_4}^{3-}$ to $Eu^{3+}$ ions and the maximum emission spectrum was the red luminescence peaking at 619 nm when the concentration of $Eu^{3+}$ ion was 0.10 mol.

• 상하수도학회지
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• 제21권6호
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• pp.679-687
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• 2007

Nanoscale zero valent ion (nZVI) technology is emerging as an innovative method to treat contaminated groundwater. The activity of nZVI is very high due to their high specific surface area, and supporting this material can help to preserve its chemical nature by inhibiting oxidation. In this study, nZVI particles were attached to granular ion-exchange resin through borohydride reduction of ferrous ions, and chemical reduction of nitrate by this material was investigated as a potential technology to remove nitrate from groundwater. The pore structure and physical characteristics were measured and the change by the adsorption of nZVI was discussed. Batch tests were conducted to characterize the activity of the supported nZVI and the results indicated that the degradation of nitrate appeared to be a pseudo first-order reaction with the observed reaction rate constant of $0.425h^{-1}$ without pH control. The reduction process continued but at a much lower rate with a rate constant of $0.044h^{-1}$, which is likely limited by mass transfer. To assess the effects of other ions commonly found in groundwater, the same experiments were conducted in simulated groundwater with the same level of nitrate. In simulated groundwater, the rate constant was $0.078h^{-1}$ and it also reduced to $0.0021h^{-1}$ in later phase. The major limitation in application of ZVI for nitrate reduction is ammonium production. By using a support material with ion exchange capacity, the problem of ammonium release can be solved. The ammonium was not detected in the batch test, even when other competitive ions such as calcium and potassium existed.

• 한국산학기술학회논문지
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• 제13권7호
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• pp.3252-3260
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• 2012

6M HCl 용매 하에서 2,2'-bipyridine과 chromium(VI) trioxide의 반응을 통하여 2,2'-bipyridinium chlorochromate[$C_{10}H_8N_2HCrO_3Cl$]를 합성하여, 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매 하에서 2,2'-bipyridinium chlorochromate를 이용하여 벤질 알코올의 산화반응을 측정한 결과 유전상수(${\varepsilon}$) 값이 큰 용매 즉, 시클로헥센<클로로포름<아세톤$p-CH_3$, H, m-Br, $m-NO_2$)을 효과적으로 산화시켰다. 그리고 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반 응속도를 증가시켰다. 또한 Hammett 반응상수(${\rho}$) 값은 -0.64(303K) 이었다. 이러한 알코올류의 산화반응성은 polysilsesquioxane과 같은 고분자물질을 용해시켜 코팅제로 활용할 때 열안정성과 같은 물성을 연구하는데 중요한 인자 가 될 수 있다. 그러므로 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어나는 메카니즘임 을 알 수 있었다.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.6000-6007
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• 2013

유기합성 과정에서 응용범위가 넓고 안정한 알코올류의 산화제에 대해 많은 연구가 진행 되고 있으며, 그중에서도 Cr(VI)-계열의 시약들이 산화제로 널리 이용되어 왔다. 그러므로 유기 용매에 잘 용해되고, 일차 알코올을 알데히드까지만 산화시키는 산화제의 합성과 그에 따르는 메카니즘 규명이 필요하게 되었다. Cr(VI)-헤테로고리 착물인 Cr(VI)-isoquinoline를 합성하여, 적외선 분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 또한 여러가지 용매 하에서 Cr(VI)-isoquinoline를 이용하여 벤질 알코올의 산화반응을 측정한 결과 유전상수(${\varepsilon}$) 값이 큰 용매 순서인 시클로헥센<클로로포름<아세톤$CH_3$, m-Br, m-$NO_2$)을 효과적으로 산화시켰다. 여기서 전자받개 그룹들은 반응 속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$) 값은 -0.69(308K) 이였다. 그러므로 본 실험에서 알코올의 산화반응 과정은 먼저 크로메이트 에스테르 형성과정을 거친 후, 속도결정단계에서 수소화 전이가 일어나는 메카니즘임을 알 수 있었다.

• 한국산학기술학회논문지
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• 제14권1호
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• pp.499-505
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• 2013

6M-HCl 용매 하에서 헤테로고리 화합물인 4-(dimethylamino)pyridine과 chromium(VI) trioxide의 반응을 통하여 4-(dimethylamino)pyridinium chlorochromate[$C_7H_{10}N_2HCrO_3Cl$] 착물을 합성하여, 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매 하에서 4-(dimethylamino)pyridinium chlorochromate를 이용하여 벤질알코올의 산화반응을 측정한 결과 유전상수(${\varepsilon}$) 값이 큰 용매 즉, 시클로헥센<클로로포름<아세톤$H_2SO_4$)를 이용한 N,N'-디메틸포름아미드 용매 하에서 4-(dimethylamino)pyridinium chlorochromate는 벤질 알코올과 그의 유도체들(p-$OCH_3$, m-$CH_3$, H, m-$OCH_3$, m-Cl, m-$NO_2$)을 효과적으로 산화시켰다. 그리고 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰다. 또한 Hammett 반응상수(${\rho}$) 값은 -0.68(303K) 이었다. 그러므로 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어나는 메카니즘임을 알 수 있었다.

• 공업화학
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• 제25권6호
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• pp.648-653
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• 2014

크롬(VI)-헤테로고리 착물(2,4'-비피리디늄 클로로크로메이트)을 합성하여, 적외선 분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였고, 여러 가지 용매 하에서, 2,4'-비피리디늄 클로로크로메이트를 이용하여 벤질알코올의 산화반응을 측정한 결과, 유전상수값의 증가에 따라 반응도 증가했다는 것을 보였다. 그 순서는 : N,N-디메 틸포름아미드(DMF) > 아세톤 > 클로로포름 > 시클로헥센산 촉매(HCl)를 이용한 DMF 용매 하에서, 2,4'-비피리디늄 클로로 크로메이트은 벤질 알코올(H)과 그의 유도체들(p-$CH_3$, m-Br, m-$NO_2$)을 효과적으로 산화시켰다. 전자받개 그룹들은 반응 속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$) 값은 -0.67 (303 K)이었다. 속도결정단계에서 크로메이트 에스테르의 형성과정을 거친 후, 양성자 전이가 일어났다.

• 전자공학회논문지D
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• 제35D권5호
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• pp.54-62
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• 1998

In a plasma etching system, ions become an important parameter in determining the wafer topography which depends on both the physical sputtering mechanism and the chemically enhanced reaction. this paper reports the energy and angular distributions of ions across the plasma sheath using a monte carlo method. The ion distribution is mainly affected by the magnitude of the sheath voltage and by the collision in the sheath. Furthemore, the local potential distribution in a plamsa sheath has been determined by solving the poisson's equation. In th is work, ionic collisions were cosidered in terms of both charge exchange and momentum transfer. The three-dimensional distributions of ions were calculated with varying the input process conditions in the plasma reactor.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1355-1359
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• 2006

Due to its efficient red emission, $Eu^{3+}$ ion has been doped in various host materials. $GdCa_4B_3O_{10}:Eu^{3+}$ phosphor for red emission has been prepared by solid state reaction. Photoluminescence properties for the phosphor under UV and VUV excitation were investigated. The $GdCa_4B_3O_{10}:Eu^{3+}$ phosphor under both excitation conditions shows typical red emission spectrum centered at 611 nm with several weak peaks due to energy transfer from $^5D_O\;to\;^7F_J(J=1,2,3,4)$ of $Eu^{3+}$ ion. On the other hand, the activator content exhibiting the concentration quenching under UV and VUV irradiation is 10 mole% and 2.5 mole%, respectively.

• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.505-510
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• 2006

A gallocyanine-bound nanoporous titanium dioxide electrode system was investigated to carry out a mediated enzyme reaction. Gallocyanine was bound either directly or through an aminopropylsilane linker to the film of nanoporous titanium dioxide and used as a mediator for nitrate reductase in the mediated enzymatic nitrate reduction. The electrode with the aminopropylsilane linker showed 20% higher efficiency of electron transfer at the same potential than that directly linked. The prepared electrodes showed $0.26{\mu}mol/h$ nitrate reduction at a $100mm^2$ surface of the electrode, and linear current response on nitrate ion concentration up to 1.0 mM, which is very useful as a biosensor of nitrate ion in water.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.1019-1023
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• 2008

Photoluminescence properties of $SrTiO_3$:Sm red phosphors synthesized by solid state reaction method were studied under 254 nm excitation. Emission bands at 576 nm and 616 nm in heavily $Sm^{3+}$ ion doped $SrTiO_3$:Sm phosphors were observed, which were attributed to $^4G_{5/2}\rightarrow{^6}H_{5/2}$ and $^4G_{5/2}\rightarrow{^6}H_{7/2}$ transition of $Sm^{3+}$, respectively. The $Sm^{3+}$ ion concentration exhibiting the maximum emission intensity in the $SrTiO_3$:Sm was 30 mol%. The luminescence caused by $Sm^{3+}$ in the $SrTiO_3$:Sm phosphors was interpreted by the energy transfer between $Sm^{3+}$ ions.