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정의덕,강신원,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.1
A study on the remediation of heavily Fe ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCI, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during 1 hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal recovery of Fe were 15g/ℓ and 5g/ℓ from the oxalic acid complexes, respectively.
정의덕,강신원,박덕수,신학기,백우현 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5
A study on the removal of Pb ion from Pb-contaminated soil was carried out, using ex-situ extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt (IDA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1 : 15 and 1 : 20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction, were 368.8 ppm and 267.5 ppm, respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide, form the precipitation of lead hydroxide and lead sulfide, and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/ℓ for the TA washing solution and 4 g/ℓ , 5 g/ℓ for the IDA washing solution, respectively. The efficiency of recycle for TA and IDA washing solution were 78.8%, 95.1% and 89.2%, 96.6%, at third extractions under Na_2S and Ca(OH)_2, respectively.
백우현,정의덕,윤천기 한국환경과학회 2000 한국환경과학회지 Vol.9 No.5
The characteristics of Far-infrared rays mineral water(FIR water) have been compared to the tap water by means of relationship between FIR water and Nuclear Magnetic Resonance spectroscopy(NMR), FIR water and thermography, FIR water and velocity of blood, FIR-water and pH, FIR water and dissolved oxygen(DO), FIR water and Oxidation-Reduction Potential(ORP), using the development FIR water purification of grand prix system. From the experimental result are quite satisfactory when compared with the tap water. Also, the FIR water were evaluated to see if those are tasty and healthy using the Hashimoto's Mineral Balance Index. As a result, FIR-water was found as tasty and healthy.
A REMARK CONCERNING UNIVERSAL CURVATURE IDENTITIES ON 4-DIMENSIONAL RIEMANNIAN MANIFOLDS
Euh, Yun-Hee,Jeong, Cho-Hee,Park, Jeong-Hyeong Korean Mathematical Society 2012 대한수학회보 Vol.49 No.5
We shall prove the universality of the curvature identity for the 4-dimensional Riemannian manifold using a different method than that used by Gilkey, Park, and Sekigawa [5].
NOTES ON A QUESTION RAISED BY E. CALABI
Euh, Yunhee,Sekigawa, Kouei Korean Mathematical Society 2016 대한수학회보 Vol.53 No.1
We show that any orthogonal almost complex structure on a warped product Riemannian manifold of an oriented closed surface with nonnegative Gaussian curvature and a round 4-sphere is never integrable. This provides a partial answer to a question raised by E. Calabi.
Characteristics of Bubble Departure Frequency in a Low-Pressure Subcooled Boiling Flow
EUH, Dongjin,OZAR, Basar,HIBIKI, Takashi,ISHII, Mamoru,SONG, Chul-Hwa Atomic Energy Society of Japan 2010 Journal of nuclear science and technology Vol.47 No.7
<P>In order to measure the bubble departure frequency, a flow visualization system was set up on a vertical annulus test section with a heater rod by using a high-speed camera. In this study, we developed an efficient methodology of image processing for obtaining the bubble departure frequency data. Bubble nucleation was investigated under various thermal hydraulic conditions of water, which correspond to pressures from 167 to 346 kPa, mass fluxes from 214 to 1869 kg/m<SUP>2</SUP>s, heat fluxes from 61 to 238 kW/m<SUP>2</SUP>, and subcooling degrees from 7.5 to 23.4 K. The characteristics of bubble departure frequency were analyzed with the present data. The measured data was compared with models available in existing literature and a more plausible model was proposed.</P>
Euh, D.J.,Kim, S.,Kim, B.D.,Park, W.M.,Kim, K.D.,Bae, J.H.,Lee, J.Y.,Yun, B.J. Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.5
Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of $1.43m{\times}1.43m{\times}0.11m$. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.
Euh, D.J.,Kim, K.H.,Youn, Y.J.,Bae, J.H.,Chu, I.C.,Kim, J.T.,Kang, H.S.,Choi, H.S.,Lee, S.T.,Kwon, T.S. Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.7
In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP ($\underline{A}$PR+ $\underline{C}$ore Flow & $\underline{P}$ressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four-cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.