• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.113-120
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• 2000

In this study, we composed algorithm for DIAL(Differential Absorption Lidar). We investigated the absorption spectrum of $O_3$, $SO_2$ and $NO_2$ dependent on wavelengths using data base UV-Bank and determined the optimized wavelength model. Here, the selected optimal wavelengths are 292.00(${\lambda}_{on}$), 295.20 (${\lambda}_{off}$) for $O_3$, 299.38(${\lambda}_{on}$), 300.05 (${\lambda}_{off}$) for $SO_2$ and 448.00(${\lambda}_{on}$), 449.85(${\lambda}_{off}$) for $NO_2$. In particular, we established the supposed model of DIAL and simulated the error of measuring distance using the selected optimal wavelength. In the model-I with telescope of 300 mm diameter, laser energy of 3 mJ and transmission of 10000 shots, maximum distances are 4 km for $O_3$ measurement and 5 km for $SO_2$ and $NO_2$ measurements. Also, in the model-II with telescope of 600 mm diameter, laser energy of 30 mJ and transmission of 10000 shots, maximum distances are 13 km for $SO_2$ and $NO_2$ measurements.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.172-172
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• 2013

최근에 디스프로슘 이온이 도핑된 형광체의 백색 발광 현상 때문에 백색 발광 소재의 제조에 관한 연구가 상당한 관심을 끌고 있다. 본 연구에서는 $Eu^{3+}$와 $Dy^{3+}$ 이온의 몰 비를 변화시키면서 $BaNb_2O_6:RE^{3+}$ (RE=Eu, Dy) 형광체 분말을 합성한 결과를 보고한다. 특히 활성제 이온인 $Eu^{3+}$와 $Dy^{3+}$ 이온의 몰 비에 따른 $BaNb_2O_6$ 형광체 분말의 결정 구조, 입자의 모양과 크기, 흡광과 발광 스펙트럼의 변화를 관측하였고, 최적의 합성 조건을 제시하고자 한다. 파장 393 nm로 여기 시킨 $Dy^{3+}$ 이온의 몰 비에 따른 $BaNb_2O_6$ 형광체 분말의 발광 스펙트럼은 580 nm에 주 피크를 갖는 황색 스펙트럼이 관측되었다. 이 발광 신호는 $^4F_{9/2}-^6H_{13/2}$ 전이 신호이다. $Dy^{3+}$ 이온의 몰 비가 0 mol인 경우에는 발광 신호가 검출되지 않았다. $Dy^{3+}$ 이온의 몰 비가 0.10 mol일 때 발광 피크의 세기는 최대이었으며, $Dy^{3+}$ 이온의 몰 비가 더욱 증가함에 따라 발광 스펙트럼의 세기는 계속 증가하지 않고 갑자기 감소하기 시작하였다. 이것은 $Dy^{3+}$ 이온의 몰 비가 임계값을 초과하여 더욱 증가하면 모체 격자들 사이에 치환 고용되어 있는 $Dy^{3+}$ 이온들 사이의 거리가 더욱 가까워져서 $Dy^{3+}$ 이온들이 서로 용이하게 결합함으로써 내부 산란에 의하여 발광의 세기가 감소함을 의미한다. 흡광 스펙트럼의 경우에, $Dy^{3+}$ 이온의 몰 비가 0.01 mol일때 형광체 분말은 두 종류의 흡광 스펙트럼을 나타내었다. 첫째는 $Dy^{3+}$ 양이온과 $O^{2-}$ 음이온들 사이에 발생한 전하 전달 밴드에 의해 발생하는 310 nm를 정점으로 하여 280~340 nm 영역에 걸쳐서 광범위하게 분포하는 흡광 신호가 관측되었으며, 둘째는 $Dy^{3+}$ 이온의 $4f^9$ 전자 배열 내에서 발생하는 4f-4f 전이 신호로서, 이것은 350~500 nm 영역에 걸쳐서 비교적 밴드폭이 좁은 다수의 흡광 신호가 나타났다. 본 실험에서는 다섯 개의 피크를 갖는 흡광 신호가 검출되었는데, 이중에서 제일 강한 주 피크인 393 nm의 흡수 파장은 모체 격자 내에 있는 $Dy^{3+}$ 이온의 바닥 상태인 $^6H_{15/2}$ 준위에서 여기 상태인 $^4F_{7/2}$ 인 에너지 준위로 전이하면서 발생한 신호이며, 이에 비하여 상대적으로 흡광 세기가 약한 370, 432, 458, 370 nm의 흡수 파장이 관측되었다.

• Restorative Dentistry and Endodontics
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• v.29 no.6
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• pp.504-514
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• 2004

This study compared the dentin shear bond strengths of currently used dentin bonding agents that were irradiated with an LED (Elipar FreeLight, 3M-ESPE) and a halogen light (VIP, BISCO). The optical characteristics of two light curing units were evaluated. Extracted human third molars were prepared to expose the occlusal dentin and the bonding procedures were performed under the irradiation with each light curing unit. The dentin bonding agents used in this study were Scotchbond Multipurpose (3M ESPE), Single Bond (3M ESPE), One-Step (Bisco), Clearfil SE bond (Kuraray), and Adper Prompt (3M ESPE), The shear test was performed by employing the design of a chisel-on-iris supported with a Teflon wall. The fractured dentin surface was observed with SEM to determine the failure mode. The spectral appearance of the LED light curing unit was different from that of the halogen light curing unit in terms of maximum peak and distribution. The LED LCU (maximum peak in 465 nm) shows a narrower spectral distribution than the halogen LCU (maximum peak in 487 nm). With the exception of the Clearfil SE bond (P < 0.05), each 4 dentin bonding agents showed no significant difference between the halogen light-cured group and the LED light-cured group in the mean shear bond strength (P > 0.05). The results can be explained by the strong correlation between the absorption spectrum of camphoroquinone and the narrow emission spectrum of LED.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.536-542
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• 1988

A nickel(Ⅱ) complex, Ni(IAA-NBz) (IAA-NBz') with ligand, N-benzylisonitrosoacetyl acetone imine (H-IAA-NBz) has been synthesized. This complex is very stable at room temperature and has cis-form and trans-form isomers. The ratio of nickel (Ⅱ) ion and ligand combined is 1 : 2. The elemental analysis, ir, nmr. electronic spectra and mass spectra have been studied. It is suggested from these studies that the isonitroso group of one ligand, H-IAA-NBz coordinates to nickel(Ⅱ)ion through the nitrogen atom to form five-membered ring, while that of the other ligand, H-IAA-NBz coordinates to nickel (Ⅱ) ion through the oxygen atom to form six-membered ring in square-planar complex.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.87-87
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• 2022

최근 국내외 이상기후 변화로 인해 일사량 증가 및 하천, 호소의 체류시간이 늘어남에 따라 조류의 과대성장이 빈번히 발생하고 있다. 하천의 조류는 크게 녹조류, 남조류, 규조류로 분류되며, 남조류 중 일부 종은생장하는 과정에서 생성하는 냄새물질, 독성물질의 배출로 문제를 야기하고 있다. 국민의 안전을 도모하기 위해 국내에서는 조류경보제, 수질예보제를 시행하고 있으며, 이는 유해남조류세포와 Chl-a농도에 따라 발령이 된다. 이렇듯 유해남조류와 Chl-a 측정은 매우 중요하며, 현재 조류의 분석방법은 현장샘플을 하여 조류검경을 통해 산정하기 때문에 시간이 많이 소요되며, 조류발생시 즉각대응이 힘들며, 육안으로 유해남조류인지 구별하기가 어렵다. 최근 원격탐사를 통해 조류의 대체 인자인 Chl-a, Phycocyanin을 통해 조류농도를 분석하고 있으나, 광합성을하는 모든 조류에는 Chl-a가 함유되어 있어 남조류와 녹조류의 정확히 구별하는데 한계점이 있다. 본 연구에서는 조류배양액을 초분광센서를 통해 조류스펙트럼을 취득하고, 남조류와 녹조류의 최대 흡수 스펙트럼을 추출하여 스펙트럼의 순간기울기 변화를 통해 남조류와 녹조류의 종분류하였다.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.636-643
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• 1999

Green-emission intensity of a $Zn_{2-x}Mn_xSiO_4$ phosphor, which is a potential candidate as a green component in PDP device, significantly increases provided that the compound is additionally heat treated at 900$^{\circ}C$ after solid state reaction at 1300$^{\circ}C$. In order to verify origin of such an intensity enhancement after the additional heat treatment in association with the electronic and local structural change at around Mn ions, the Mn K-edge X-ray absorption spectra were recorded. From the analyses of the preedge peak corresponding to $1s{\rightarrow}3d$ bound state transition and XANES spectrum, it is known that most Mn ions are in +2 oxidation state and substitute Zn ion site regardless of the thermal treatment. In addition, EXAFS analyses revealed that Mn ions formed $MnO_4$ tetrahedra with the Mn-O bond length shortened by 0.01${\AA}$ and with reduced Debye-Waller factor in the thermally treated sample.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.161-169
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• 2017

The cone beam computed tomography(CBCT) which can acquire 3-dimensions images is widely used for confirmation of patient position before radiation therapy. In this study, through the simulation using the Monte Carlo technique, we will analyze the exposure dose by cone beam computed tomography and present the standardized data. For the experiment, MCNPX(ver. 2.5.0) was used and the photon beam spectrum was analyzed after Cone beam was simulated. As a result of analyzing the photon beam spectrum, the average energy ranged from 25.7 to 37.6 keV at the tube voltage of 80 ~ 120 kVp and the characteristic X-ray energy was 9, 60, 68 and 70 keV. As a result of using the water phantom, the percentage depth dose was measured, and the maximum dose appeared on the surface and decreased with depth. The absorbed dose also decreased as the depth increased. The absorbed dose of the whole phantom was 9.7 ~ 18.7 mGy. This is a dose which accounts for 0.2% of about 10 Gy, which is generally used for radiation therapy per week, which is not expected to have a significant effect on the treatment effect. However, it should not be overlooked even if it is small compared with prescription dose.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.56-60
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• 2011

Optical properties of $T_{0.2}Fe_{2.8}O_4$ (T = V, Cr, Mn) thin films derived from ferrimagnetic $Fe_3O_4$ were investigated by spectroscopic ellipsometry in the 1~8 eV photon-energy range. The difference in optical-absorption spectrum between the ternary compounds and $Fe_3O_4$ was analyzed based on preferable sites in spinel structure and iconicity of the doped V, Cr, and Mn ions. The observed absorption spectra from $Fe_3O_4$ and the ternary compounds can be interpreted as mainly due to charge-transfer transitions of Fe d electrons characterized by absorption structures with wide energy width. Also, the observed absorption structures with narrow energy width can be interpreted as due to crystal-field transitions between different d electron configurations of tetrahedral $Fe^{3+}(d^5)$ ion. The transitions were described in terms of spin-polarized electronic states of $Fe_3O_4$.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.201-206
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• 1986

A new analytical reagent N-benzylisonitrosoacetylacetone imine (H-IAA-N-Bz) has been synthesized and identified its structure by IR, NMR and mass spectra. H-IAA-N-Bz forms a copper chloroform-soluble complex in a basic aqueous solution (pH = 7.0∼10.0). The other optimum conditions for the spectrophotometric study of the copper complex have been determined at 420nm. Beer's law is obeyed below the concentration of 64$\mu$g of copper per 10ml of chloroform. The composition of the copper complex has been found to be $Cu(IAA-N-Bz)_2$ and the over-all stability constant is calculated to be $8.55 {\times} 10^6$. The molar absorption coefficient, $\varepsilon$ of the $Cu-(IAA-N-Bz)_2 $complex is 3500l/$cm{\cdot}mol$.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.17-22
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• 2003

The experimental FT-IR spectra and DTA curves of the $PbO-Bi_2O_3-B_2O_3-SiO_2$ glasses have been investigated. The composition ratio dependence of glass transition temperature showed that the structure of this glass system changes at 60 mol% $Bi_2O_3$. We have observed that the FT-IR spectra of the investigated samples with high bismuth content are dominated by bands associated to the structural units of the heaviest cation, $Bi^{3+}$ and the boron atoms in the treated samples are three and four coordinated even for very high $Bi_2O_3$ content. The low intensity of these non-bridging oxygen bands, for high PbO content glasses, can be attributed to the strong network-forming roles of PbO. The glasses absorption bands exhibited a greater change in intensities on crystallization.