• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.292-303
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• 2004

기존의 지수실험장치에 PLC와 스텝핑 모터로 구성된 자동화 제어장치를 부착하여 중성자 선원과 검출기를 자동으로 정확하게 이동할 수 있도록 개선하였다. 또한 GENIE 2000 라이브러리에 기반을 둔 MCA와 PLC를 동시에 구동할 수 있는 통합자동화 프로그램을 개발하였다. 이와 같이 체계적인 장치로 개선된 실험장치를 사용하여 고리 1 호기의 사용후핵연료 집합체, Cl4, Jl4 및 G23과 고리 2 호기의 사용후핵연료 집하체, J44의 대한 지수실험을 수행하였다. 그 결과 4 개 집합체에 대한 평균 지수감쇠계수는 각각 0.1302, 0.1267, 0.1247 및 0.1210으로 결정되었다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 요약집 춘계학술발표대회
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• pp.301.1-301.1
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• 2004

• Journal of Photoscience
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• 제9권2호
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• pp.296-298
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• 2002

Irreversible photobleaching of bacteriorhodopsin (bR), namely denaturation induced by illumination of visible light, was investigated by absorption kinetic measurements. The denaturation kinetics revealed that light illumination significantly enhanced the structural decay of bR. The kinetic analyses showed that the molecular structure of bR denatures according to a single-exponential decay, whereas irreversible photobleaching has two decay components. The decay constant of the slow component of photobleaching is almost same as that in the dark. An Arrhenius plot of the denaturation kinetic constants for the fast and slow components showed similar activation energies of approximately 19 kcal/mol.

• 대한환경공학회지
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• 제35권4호
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• pp.276-282
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• 2013

하수재이용수는 부족한 수자원 문제를 해결할 수 있는 대표적인 대안으로 주목받고 있다. 본 연구에서는 하수재이용수의 공급시 유리잔류염소의 수체감소 특성을 온도별(5, 15, $25^{\circ}C$), 초기 주입농도별(1, 2, 4, 6 mg/L)로 살펴보았고 그 결과를 이용하여 최적 염소주입량을 산정하는 방법에 대하여 연구하였다. 하수재이용수는 정수와 비교하여 염소주입시 반응속도가 초기에 매우 빠르게 나타나 기존의 general first-order decay model ($C_t=C_o(e^{-k_bt})$)을 사용하기에 부적합하여 exponential firstorder decay model ($C_t=a+b(e^{-k_bt})$)을 적용한 결과 유리잔류염소의 감소를 더욱 정확하게 예측할 수 있었다($r^2$=0.872~0.988). 수체감소계수를 산출한 결과 초기주입량 1 mg/L, $25^{\circ}C$의 조건에서 653 $day^{-1}$로 가장 크게 나타났고, $5^{\circ}C$, 초기주입량 6 mg/L의 조건에서 3.42 $day^{-1}$로 가장 낮았다. 수체감소계수는 온도가 증가함에 따라 수체감소계수는 증가하는 경향을 나타내었고, 초기 주입농도가 증가함에 따라 수체감소계수는 감소하는 경향을 나타내었다. 적정 초기 염소요구량을 산정하기 위해서 전체 반응기간을 0~30분, 30~5,040분으로 구분한 후, 30~5,040분의 실험결과를 사용한 예측식을 사용함으로써 더욱 정확한 염소주입량 산정을 할 수 있었다. 또한, 온도별로 최적 염소주입량을 산정한 결과 염소주입 후 4시간이 경과한 시점에서 유리잔류염소 0.2 mg/L를 유지하기 위해서는 온도(x)별 초기 염소요구량(y)의 관계를 y = 1.409 + 0.450x와 같이 얻을 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제12권1호
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• pp.58-66
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• 2021

Spiral-wound woven wire meshes packed bed rotating cylinder electrode was used for the simultaneous removal of cadmium (Cd) and copper (Cu) from a binary solution. The effects of weight percent of each metal on the removal and current efficiencies were studied at an operating current of 345A, while the effect of current on the removal efficiency of both metals was investigated at three levels of current (240, 345.and 400 mA). The experiments were carried out at constant rotation speed 800 rpm, pH = 3, and a total concentration of metals (500 ppm). The results showed that the removal efficiency of copper increased from 89% to 99.4% as its weight percent increased from 20% to100%. In a similar fashion, the removal efficiency of cadmium increased from 81% to 97% as its weight percent increased from 20% to100%. The results confirmed that the removal efficiency of any metals declined in the presence of the other. Increasing of current resulted in increasing the removal efficiency of both metals at different weight percents. The results confirmed that current efficiencies for removing of copper and cadmium simultaneously decline with increasing of electrolysis time and weight percent of cadmium or with decreasing the weight percent of copper. Current efficiency was higher at the initial stage of electrolysis for all weight percents of metals. The results showed that the decay of copper concentration was exponential at all weight percents of copper, confirming that the electrodeposition of copper is under mass transfer control in the presence of cadmium. While the decay of cadmium concentration was linear at lower weight percent of cadmium then changed to an exponential behavior at high weight percent of cadmium in the presence of copper.

• Journal of Information Display
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• 제12권1호
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• pp.23-27
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• 2011

The correlation between the temporal and spatial variations of the elastic constant and temperature change was examined for a light guide plate (LGP) adopted in the edge-lit light-emitting-diode backlight for mobile applications, using the micro- Brillouin light scattering method. The velocity of sound and the elastic constant $C_{11}$ of an LGP made from bisphenol-A polycarbonate (PC) were investigated as functions of temperature, time, and position on the LGP. The temporal variation of $C_{11}$ exhibited an exponential decay, while the spatial variation of $C_{11}$ reflected the temperature distribution on the LGP. The glass transition temperature of the PC LGP was found to be located at $155^{\circ}C$. The result showed that systematic transformation between the elastic property and the temperature is possible and that the temperature distribution on the bulk LGP can be accurately probed via the present experiment method, without using any special temperature measurement equipment.

• Journal of Astronomy and Space Sciences
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• 제1권1호
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• pp.23-34
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• 1984

A bubble trapped in the liquid manifold of INTELSAT IV F-7 spacecraft caused a mass imbalance between the System 1 propellant tanks and a wobble half angle of 0.38 degree to 0.48 degree. A maneuver on May 14, 1980 passed the bubble through the axial jet and allowed propellant to redistribute. A 0.2 rpm change in sin rate was observed with an exponential decay time constant of 6 minutes. In this paper, moment of inertia, tank geometry and hydrodynamic models are derived to match the observed spin rate data. The values of the total mass of propellant considered were 16, 19 and 20 kgs with corresponding mass imbalances of 14.3, 15 and 15.1 Kgs, respectively. The result shows excellent agreement with observed spin rate data but it was necessary to assume a greater mass of hydrazine in the tanks than propellant accounting indicated.

• Journal of Pharmaceutical Investigation
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• 제35권5호
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• pp.333-336
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• 2005

The objective of this study was to investigate the stability of tetracycline HCl on encapsulation into and inside reverse micelles. To do so, tetracycline HCl was first mixed with cetyltrimethylammonium bromide, water and ethyl formate to make reverse micelles. The degradation kinetics of tetracycline HCl inside the reverse micelles was then assessed by scrutinizing its stability data. Under our experimental conditions, the reverse micelles formed spontaneously in absence of any mixing devices. During the preparation of the reverse micelles, however, considerable portions of tetracycline HCl underwent a chemical reaction (e.g., epimerization). For instance, $51.4{\pm}0.6%$ of an initial concentration of tetracycline HCl was transformed into a degradation product. Once dissolved inside the reverse micelles, the degradation of tetracycline HCl followed an exponential decay pattern. The plot of log{the degradation rate of tetracycline HCl} versus log{tetracycline HCl concentration} made it possible to determine the order of degradation reaction and rate constant. It was proven that the degradation of tetracycline HCl inside the reverse micelles followed a first order kinetics with a rate constant of 0.0027 $hour^{-1}$. Meriting further investigation might be formulation studies to stabilize tetracycline HCl on encapsulation into and inside the reverse micelles.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4722-4730
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• 2022

This paper introduces a new point depletion-based source term calculation code named BESNA (Bateman Equation Solver for Nuclear Applications), which is aimed to estimate nuclide inventories and source terms from spent nuclear fuels. The BESNA code employs a new modified CE/CM (Constant Extrapolation - Constant Midpoint) predictor-corrector scheme in depletion calculations for improving computational efficiency. In this modified CE/CM scheme, the decay components leading to the large norm of the depletion matrix are excluded in the corrector, and hence the corrector calculation involves only the reaction components, which can be efficiently solved with the Talyor Expansion Method (TEM). The numerical test shows that the new scheme substantially reduces computing time without loss of accuracy in comparison with the conventional scheme using CRAM (Chebyshev Rational Approximation Method), especially when the substep calculations are applied. The depletion calculation and source term estimation capability of BESNA are verified and validated through several problems, where results from BESNA are compared with those calculated by other codes as well as measured data. The analysis results show the computational efficiency of the new modified scheme and the reliability of BESNA in both isotopic predictions and source term estimations.

• 센서학회지
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• 제19권6호
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• pp.443-448
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• 2010

In this work, the scintillation properties of CsI:Na crystal were investigated as radiation detection sensor. This scintillation material was grown by a 2-zone vertical Bridgman method. Under X-ray excitation the crystal shows a broad emission band between 280 nm and 690 nm wavelength range, peaking at 413 nm. Energy resolution for $^{137}Cs$ 662 keV $\gamma$-rays of the crystal was measured to be 6.9 %(FWHM). At room temperature, the crystal exhibits three exponential decay time components. The fast and major component of scintillation time profile of the crystal emission decays with a 457 ns time constant. Absolute light yield of the crystal was estimated to be 53,000 ph/MeV using LAAPD. The sample crystal shows proportionality of 30 % in the measured energy range from 31 to 1,333 keV. And the $\alpha/\beta$ ratio of the crystal was 0.14.