• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.893-900
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• 2021

In this study, air density in a narrow test section is measured using a laser absorption spectroscopy system that detects oxygen absorption lines. An absorption line pair at 13156.28 and 13156.62 cm^-1 are detected. A gas chamber with a height of 40 mm is used as a narrow test section. A triangular spiral-shaped laser path is applied in the gas chamber to amplify absorption strength by extending laser beam path length. A well-known logarithm amplifier and a secondary amplifier are used to electrically amplify absorption signal. An AC-coupling is applied after the logarithm amplifier for signal saturation prevention and noise suppression. Procedure of calculating spectral absorbance from output signal is introduced considering the logarithm amplifier circuit configuration. Air density is determined by fitting the theoretically calculated spectral absorbance to the measured spectral absorbance. Test conditions with room temperature and a pressure range of 10~100 kPa are made in a gas chamber using a Bourdon pressure gauge. It is confirmed that air density in a narrow test section can be measured within a 16 % error through absorption signal amplification using a triangular spiral-shaped beam path and a logarithm amplifier.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.1-7
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• 2006

The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with $NH_2OH$ HCl, and oxidized to Pu(IV) and Pu(VI) with $NaNO_2$ and $HClO_4$, respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with $NH_2OH$ HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 m and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-Vis absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.576-580
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• 2006

Mercury-free lamp, external electrode fluorescent lamp (EEFL) which includes the xenon gas, is now going on the research for the replacement of mercury lamp. The densities of excited xenon atom in the $1s_4$ resonance state and the $1s_5$ metastable state are investigated in the EEFL by a laser absorption spectroscopy under various gas pressures. We have measured the absorption signals for both $1s_4$ resonance and the $1s_5$ metastable state in the EEFL by varying the discharge currents for a given pressure. This basic absorption characteristic is very important for improvement of the VUV luminous efficiency of the EEFL as well as plasma display panel.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.2
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• pp.105-116
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• 2019

Oil adsorption during hair or body washing is responsible for the hair conditioning. In this study, we established a method to extract oil from a substrate, and to determine amount of adsorbed oil upon substrate using a conventional absorption spectroscopy. We controlled the mole fraction of a surfactant in a mixture of anionic and amphoteric surfactants because that it induces the coacervate that regulates amount of adsorbed oil through the alteration of oil viscosity. Based on this, we established the optimized condition for adsorption and extraction for oil. UV absorbance were employed to estimate the amount of adsorbed oil using optical absorbance after extraction via adsorption. The estimation was confirmed by comparing with a mass analysis in HPLC and an adhesive energy in AFM. It has been proved that this method can be applied to all cases of oil adsorption from the results with various cationic polymers and a complex system of the polymers which regulate the oil adsorption.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.75.1-75.1
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• 2021

MSE (Maunakea Spectroscopic Explorer)는 11.25m 구경의 망원경과 최대 4,000 개의 천체를 한 번에 관측할 수 있는 분광기를 통해 다천체 분광학 연구를 이끌 차세대 관측기기이다. 경희대학교는 망원경에 장착되는 다천체 분광기의 성능 요구사항을 바탕으로 노출 시간 소프트웨어 ETC (Exposure Time Calculator)를 개발하고 있다. ETC는 대기에 의한 연속선 소광, 방출선과 흡수선, 망원경 및 광학 기기의 투과율, 검출기의 암전류와 읽기 잡음을 바탕으로 신호 대 잡음비 S/N (Signal to Noise)을 도출하여 천체를 분광 관측하기 위한 적절한 노출 시간을 계산한다. MSE-ETC는 저분산 LR (Low Resolution, R=3,000), 중분산 MR (Moderate Resolution, R =6,000) 및 고분산 HR (High Resolution, R=40,000)의 관측 모드로 가시광선과 근적외선 영역의 S/N과 파장, 그리고 S/N과 AB등급 간의 상관관계를 보여준다. 본 포스터에서는 개발 중인 MSE-ETC 프로그램의 구조와 작동 알고리즘 및 사용 예를 발표한다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.1
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• pp.1-10
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• 2014

At present, there are few research papers on skin penetration of cosmeceutical ingredients. What is worse is that in vivo studies are hard to find. In this study, we measured skin epidermal penetration of cosmeceutical ingredients using in vivo Raman spectroscopy and compared with the results obtained from experiments using in vitro franz cell. Results showed that ascorbyl-2-glucoside, retinol, retinyl palmitate, and kojic acid were good for penetration ratio in measurement in vitro and retinol, vitamin C, and arbutin were good in measurement in vivo. Among them, retinol was best in skin penetration in vivo experiment using Raman spectroscopy and ascorbyl-2-glucoside was best in skin penetration in vitro experiment using Franz cell system. It is estimated that the differences were originated from the experimental procedures of two different methods; in vivo Raman experiment can be sensitive to the effect of epidermis and dermis as characteristics of matter by estimating the stratum corneum and in vitro measurement is evaluation of material to penetrate skin of hairless mouse. However, most penetration barrier is the stratum corneum, thus it is important to examine movement of material in the stratum corneum. We expect that these results provided useful information for many cosmetic related research.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.367-376
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• 2007

Aenigmatite, $Na_4(Fe^{2+},Ti,Fe^{3+}){_{12}}(Fe^{3+},Si){_{12}}O_{40}$, is a common constituent of sodium-rich alkaline igneous rocks and is classified a an open-branched single-chain silicate. $M\ddot{o}ssbauer$ spectroscopy of three natural aenigmatite specimens were done and the detailed crystal chemistry was obtained. Fitting of $M\ddot{o}ssbauer$ spectra led to the resolution of nine peaks. They consist of three doublets of $Fe^{2+}/oct$ and one merged peak at low velocity matching to two small peaks at high velocity which were assigned to $Fe^{3+}/tet\;and\;Fe^{2+}/oct$, respectively. Using the peak area for $Fe^{2+}\;and\;Fe^{3+}$ peaks, analytical data were recalculated. Precise assignment of $Fe^{2+}\;and\;Fe^{3+}$ ions in tetrahderal and octahedral sites revealed detailed crystal chemistry of aenigmatite. The existence of significant amounts of $Fe^{3+}/tet$ indicates that $Fe^{3+}$ has preference over $Al^{3+}$ for the tetrahedral sites. Crystal chemistry of aenigmatite (AEN1) yields the formula of $(Na_{3.97}Ca_{0.03})(Ca_{0.11}Mn_{0.59}Fe^{2+}{_{8.07}}Ti_{2.07}Mg_{0.70}Fe^{3+}{_{0.43}}Al_{0.04})(Fe^{3+}{_{0.56}}Al_{0.18}Si_{11.26})O_{40}$.

• Journal of the Mineralogical Society of Korea
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• v.6 no.2
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• pp.105-115
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• 1993

$M{\ddot{o}}ssbauer$ and Infrared absorption spectra of the iron-bearing tourmaline minerals show that the ferrous and ferric ions occupy the Y and Z octahedral sites. The Fe ions are almost ferrous, predominantly partitioning into Y site and partly take in Z site. The $Fe^{2+}$ content of the Z sites in brownish black tourmaline minerals are higher than that in blue/green tourmaline minerals. Therefore, 720 nm peak of brownish black samples is broader than that of blue/green samples in optical spectra. All of the blue/green tourmaline minerals used in experiment have only $Fe^{2+}$ ion. The IR spectra of tourmaline depend on the cation environments around OH groups, as also evidenced by their chemical analyses. There appear no difference in IR spectrum between O(1)H and O(3)H binding characters in the heat-treated samples. But the characteristic $3565cm^{-1}$ peak appears in the ferrous hydroxyl bearing silicates, where dehydroxylation temperature for OH coordinated to $Fe^{2+}$ is $700{\sim}800^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.107-111
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• 2001

Sr$_{(1-x)}$Ca$_{x}$TiO$_3$: Pr$^{3+}$ , Ga$^{3+}$ (0$\leq$x$\leq$1) 형광체의 여기 및 발광 스펙트럼과 분광 반사율을 조사하여 발광 메커니즘을 규명하고자 하였다. 발광 스펙트럼에서는 611~614nm 사이에서 peak을 가지는 하나의 적색 발광 밴드가 관찰되었으며, 조성에 따라 발광밴드의 모양이 달랐다. 이는 조성에 따른 모체의 결정 구조 변화 때문으로 생각된다. 여기 스펙트럼 끝단과 분광 반사율 스펙트럼의 흡수단은 서로 일치하였으며, 이 결과로부터 모체에 흡수된 에너지가 Pr$^{3+}$ 에 전달되어 적색광을 방출하는 것이 주된 메커니즘으로 생각된다. 한편 120$0^{\circ}C$에서 4시간동안 열처리하여 합성한 Sr$_{0.4}$Ca$_{0.6}$TiO$_3$:(0.1 mol%)Pr$^{3+}$ , (0.2 mol%)Ga$^{3+}$ 는 우수한 색순도와 휘도를 나타내었다.다.

• Korean Journal of Remote Sensing
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• v.38 no.2
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• pp.215-222
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• 2022

In this study, the effect of wavelength range and absorption cross-section used to retrieve nitrogen dioxide (NO₂) vertical column density (VCD) from Pandora was analyzed using Differential Optical Absorption Spectroscopy (DOAS). During the GEMS Map of the Air Pollution (GMAP) 2020 campaign, data from direct sunlight observation with Pandora instrument in Seosan was used, and NO₂ VCD was retrieved under four conditions. The average NO₂ VCD under the four conditions ranged from 1.22×10¹⁶~1.38×10¹⁶ molec. cm^-2, with a maximum difference of 0.16×10¹⁶ molec. cm^-2 between each condition. The fitting error averaged 3.19~9.59%, showing an error within 10% in all cases, and the RMS was 5.11×10^-3~7.16×10^-3 molec. cm^-2. The retrieved NO₂ VCD using 4 conditions shows a slope in the range of 0.98 to 1.09 and correlation of 0.96 to 0.98 in comparison with Pandonia Global Network (PGN).