• Korean Journal of Optics and Photonics
• /
• v.35 no.1
• /
• pp.1-8
• /
• 2024

Explicit expressions for the transmission pseudo-ellipsometric constants and transmittance of a semi-transparent glass substrate coated with thin films are presented to determine the optical constants of a very weakly absorbing thin film coated on a glass substrate. The intensity of the multiply reflected light inside the semi-transparent substrate is superposed incoherently and the light absorption by the substrate is properly treated, so that modeling analysis of thin films coated on a semi-transparent substrate can be performed with increased accuracy. The extinction coefficient derived from transmittance analysis is compared to that from ellipsometric analysis in the weakly absorbing region, and the difference between the two extinction coefficients is discussed in relation to the sensitivities of the transmittance and ellipsometric constants. This transmittance analysis, together with ellipsometric analysis, is applied to a glass substrate coated with a SiN thin film, and it is shown that the thickness and complex refractive index of the SiN thin film can be determined accurately, even though the extinction coefficient is very small.

• Korean Journal of Optics and Photonics
• /
• v.7 no.2
• /
• pp.129-135
• /
• 1996

We observed the absorptive optical bistability in the single layer amorphous $As_2S_3$ thin film which has an isolated electron pairs at roomtemperature, for the frist time, $Ar^+$ laser beam (λ=514.5 nm) was used as a light source and was focused by thin lens. The experiment was performed in cavityless system and the occurrence of optical bistability in this material could be explained by the temperature-dependent absorption coefficient of the sample. Also, this effect was explained by the reversible shift of the absorption edge in this material. The condition of optical bistability is determined by detuning value ($a_0L$) and this value was 0.12 when thikness of that sample was about 0.8 ${\mu}{\textrm}{m}$. The switching was observed clealy when light intensity is 150~180 mW and the swiching time was about $10^{-4}$ s.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.12 no.4
• /
• pp.227-233
• /
• 1983

• Korean Chemical Engineering Research
• /
• v.61 no.4
• /
• pp.555-560
• /
• 2023

Conventional aqueous amine-based CO₂ capture has a problem in that a large amount of renewable energy is required for CO₂ stripping and solvent regeneration in its industrial applications. This work proposes a water-lean absorbent that can reduce regeneration energy by lowering the water content in the absorbent with high absorption capacity for CO₂. To this purpose, this water-lean solvent introduced NMP (N-methyl-2-pyrrolidone), which has a higher physical solubility in CO₂ and a low specific heat capacity comparing to water, along with 3-methylaminopropylamine (MAPA), a diamine, into the absorbent. The circulating absorption capacity and absorption rate for CO₂ of this water-lean solvent were measured using a packed tower. When NMP was added to the absorbent, the absorption rate was improved. In the case of the absorbent containing 2.5M MAPA was used, the maximum circulating absorption capacity was obtained when 10 wt% of NMP was included in absorbent. The overall mass transfer coefficient increased as the concentration of NMP increased. However, at loading values higher than 0.5, the increment in mass transfer coefficient decreased as the concentration of NMP increased. When the lean loading value is low, the mass transfer resistance due to viscosity of the absorbent is low, so the overall mass transfer coefficient increases with the addition of NMP. However, as the lean loading value increases, the viscosity of the absorbent increases, and the diffusivity of CO₂ and MAPA decreases, resulting in sharply decreasing of the overall mass transfer coefficient.

• Korean Journal of Optics and Photonics
• /
• v.7 no.4
• /
• pp.357-362
• /
• 1996

The thickness and the spectrum of the complex refractive index in the region 1.5~4.5 eV, of an MNA/PMMA thin film fabricated by spin casting are determined. The film thickness and the refractive index in its transparent region is calculated by modeling the spectroscopic ellipsometry data. The extinction coefficient spectrum is obtained from the absorption spectrum in its non-transparent region. The best fit oscillator parameters of the classical Lorentz oscillator and a quantum mechanical oscillator are found. The complex refractive index spectrum by these oscillators are compared. The present technique can be applied to get the thickness and the complex refractive index of unknown polymer films and thus it will be useful in optical characterization of those films.

• Journal of the Korean Society of Radiology
• /
• v.11 no.1
• /
• pp.37-42
• /
• 2017

We measured the absorbed dose and the area dose using an ionization chamber type of area dose product (DAP) meter and measured the calibration factor in the X-ray examination. In the indirect dose measurement method, the detector was installed in the radiation part of the X-ray equipment, and the measured value was calculated as the dose at the exposure part. The instrument used to calculate the calibration factor was an X-ray equipment (DK-550R / F, DongKang Medical Co., Ltd., Seoul, Korea). The calibration method for the calibration factor was to connect the DAP meter (PD-8100, Toreck Co. Ltd., Japan) to the calibration dosimeter tube voltage of 70 kV, tube current of 500 mA, 0.158 sec. The reference dosimeter used a semiconductor (DOSIMAX plus A, Scanditronix, $Wellh{\ddot{o}}fer$, Germany). After installing the DAP meter on the front of the multi-collimator of the ionization chamber, the calibration factor of the dosimeter was obtained using the reference dosimeter for accurate dose measurement. Experimental exposure values and values from the calibration dosimeter were calculated by multiplying each calibration factor. The calibration factor was calculated as 1.045. In order to calculate the calibration coefficient according to the tube voltage in the ionization type DAP dosimeter, the absorbed dose and the area dose were calculated and the calibration factor was calculated. The corrective area dose was calculated by calculating the calibration factor of the DAP meter.

• Journal of the Society of Disaster Information
• /
• v.16 no.3
• /
• pp.577-585
• /
• 2020

Purpose: The presence of the matric suction in unsaturated soil increases the stability of the slope, but the reduction of the matric suction due to precipitation can cause sudden slope failure, resulting in a major disaster. In this paper, engineering characteristics in unsaturated state were analyzed for granite weathering soil, which is the representative mountain soil of Korea. Method: Experiments and analysis were conducted on granulated weathering soil as unsaturated shear strength relationships for moisture characteristic curves, unsaturated injection curves, and matric suction under unsaturated conditions. Result: It was analyzed that a rapid change in the matric suction for volumetric water content occurs compared to the case where the particle size distribution is poor and the particle size distribution is good. A good case for the particle size distribution indicates a relatively small permeability coefficient at the same matric suction capacity compared to a poor case. The greater thematric suction, the greater the shear strength. Conclusion: For Korea's representative soil, granulated weathering soil, the functional characteristic curves, unsaturated permeability coefficients, unsaturated shear strength, etc., which are engineering characteristics in unsaturated state, were tested to secure each correlation.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.5
• /
• pp.109-122
• /
• 2002

The water content of soil near the ground subgrade varies seasonally, and dynamic deformational characteristics of soil are affected by the variation of water content. Contrary to previous studies which used various specimens of different compaction moisture contents, the influences of water content and capillary Pressure on dynamic deformational characteristics of soil were investigated using the given specimen controlling the matric suction. RC/TS(resonant column and torsional shear) testing equipment was modified so that it can control water content with changing capillary pressure(matric suction). RC/TS tests were performed on subgrade soil collected in the KHC(Korea Highway Corporation) test road. In the field, the cross-hole tests were performed and the water contents were measured at the same site to verify the feasibility and applicability of RC/TS test results. As water content decreased, the tendency of increasing shear moduli in field was well matched with laboratory test results.

• Journal of Korea Soil Environment Society
• /
• v.4 no.2
• /
• pp.77-86
• /
• 1999

Partitioning of two hydrophobic organic compounds (HOCs), phenanthrene and naphthalene, to kaolinite and sorbed surfactants was studied to evaluate the feasibility of surfactant-enhanced remediation (SER) of contaminated subsurface systems. Sorbed surfactant partition coefficients. $K_ss$, showed a strong dependence on the surfactant sorption isotherms at low sorbed surfactant levels $K_ss$ values were at their highest and then decreased with increasing surfactant sorption densities. $K_ss$ values for SDS were always larger than corresponding $K_mic$values. For Tween 80, however. $K_ss$ values $K_mic$ were higher than $K_mic$ values only at the lower sorbed surfactant densities. HOC distribution between immobile and mobile phases varied with surfactant dose distribution coefficients increased initially with increasing surfactant concentrations and then decreased at higher doses. This observation shows directly the competition between sorbed and micellar surfactants for HOC partitioning. Overall results of this study demonstrate that surfactant sorption to the solid phase can lead to increases in HOC retardation in some SER applications. Therefore, before an SER process is selected, appropriate consideration of surfactant sorption and HOC partitioning to immobile versus mobile phases pertinent to a specific subsurface system must be contemplated.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1994.05a
• /
• pp.103-108
• /
• 1994

리튬브로마이드 수용액이 수직관내면을 따라 액막의 형태로 흘러 내릴때 수증기와의 흡수과정에 대하여 열 및 물질전달 특성을 실험하였다. 실험에서 열 및 물질전달계수는 막레이놀즈수를 30에서 200까지 변화시키면서 실시하였다. 일정한 냉방능력에서 시스템 압력을 변화시켰을 때의 열 및 물질전달계수를 측정하였다. 액막의 열전달계수는 레이놀즈수가 증가함에 따라 감소하였다. 최대 질량유량에서 최적의 막레이놀즈수가 존재하였다.