유기산 추출에 의한 철 폐광산 오염토양의 복원

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.

유기산을 이용한 납 요염토양의 복원에 관한 연구

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.

수돗물과 원적외선 기능수의 수질 특성의 비교

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].

Development of the Interfacial Area Concentration Measurement Method Using a Five Sensor Conductivity Probe

Euh, Dong-Jin,Yun, Byong-Jo,Song, Chul-Hwa,Kwon, Tae-Soon,Chung, Moon-Ki,Lee, Un-Chul Korean Nuclear Society 2000 Nuclear Engineering and Technology Vol.32 No.5

The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAC can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly than the four sensor probe. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator.

Performance Evaluation of the Safety Analysis Codes for Subcooled Boiling in a Nuclear Reactor Downcomer during the Late Reflood Phase of an LBLOCA

Euh, D.J.,Huh, B.G.,Yun, B.J.,Song, C.-H.,Kim, I.G. AMERICAN NUCLEAR SOCIETY 2008 Nuclear technology Vol.164 No.3

Development of a real-time drying control system for a pneumatic conveying dryer for sawdust in pellet production

Euh, Seung Hee,Choi, Yun Sung,Nam, Yun Sung,Lee, Chung Gun,Lee, Sang Yeol,Oh, Kwang Cheol,Oh, Jae Heun,Kim, Dae Hyun Elsevier 2018 ENERGY Vol.161 No.-

<P><B>Abstract</B></P> <P>This study presents a real-time drying control system that was developed to control air drying of sawdust in a pneumatic conveying dryer to produce high-grade wood pellets in the range of the target moisture content (MC). The real-time drying control system was installed with moisture sensors to control the ON/OFF periods of the fuel (pellet) supply motor for the sawdust to generate the heat necessary to dry the sawdust to an optimum level of 15% moisture content for pelletizing. The results of the experiment and the simulation showed that the drying efficiency improved when a buffer was introduced instead of using a conventional system, and the average moisture content of the dried sawdust was measured to be about 12.4% in a pneumatic conveying dryer without buffer and about 14.7%–15.2% in the developed real-time drying control system. This study shows that the real-time drying control system could dry the sawdust to the targeted constant moisture content, and the buffer in the pneumatic conveying dryer could improve the drying efficiency according to an increase in the resident time of the sawdust.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A real-time drying control system was developed to control the air drying process for sawdust in a pneumatic conveying dryer. </LI> <LI> Drying efficiency was improved when the buffer was present instead of the conventional system. </LI> <LI> The real-time drying control system dries the sawdust with constant range compared to the initial moisture content. </LI> </UL> </P>

Characteristic function of Cayley projective plane as a harmonic manifold

EUH, Yunhee,PARK, JeongHyeong,SEKIGAWA, Kouei 'Department of Mathematics, Hokkaido University' 2018 Hokkaido mathematical journal Vol.47 No.1

IDENTIFICATION OF TWO-DIMENSIONAL VOID PROFILE IN A LARGE SLAB GEOMETRY USING AN IMPEDANCE MEASUREMENT METHOD

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.

A FLOW AND PRESSURE DISTRIBUTION OF APR+ REACTOR UNDER THE 4-PUMP RUNNING CONDITIONS WITH A BALANCED FLOW RATE

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.